An examination of direct selection typing rate and accuracy for persons with high-level spinal cord injury using QWERTY and default on-screen keyboards. A single-subject rapid alternating treatment design with replication was used to compare the efficiency of two keyboard layouts, QWERTY and default, for persons with high-level spinal cord injury. The LIAISON system and proportional-drive chin controller provided computer access/writing to four subjects. Three efficiency characteristics were examined: keystrokes per minute, keystroke accuracy, and keystroke corrections. Baseline sessions were followed by 10 to 12 alternating treatment sessions for all subjects. Each alternating treatment session involved six text entry trials--three text entry trials using the QWERTY keyboard layout and three using the default keyboard layout. Four follow-up sessions were completed for each subject using the default keyboard configuration. Data analysis revealed that the default keyboard layout provided greater keystrokes per minute for two of the subjects. The keystroke accuracy was between 98% and 100% for all subjects on both keyboard layouts. The findings of this investigation revealed no clinically significant difference in typing performance across the two keyboard layouts for the participating subjects. The results also indicate that previous experience with a keyboard configuration is an important factor in determining performance. A possible treatment interaction or carryover effect between the two keyboard configurations was noted and has implications for the type of single-subject design used in future investigations.


Application of a programmable dual-channel adaptive electrical stimulation system for the control and analysis of gait. A dual-channel electrical stimulation system with a stimulator and a programmer/stride analyzer was designed for clinical rehabilitation of gait and for subsequent daily use as an orthotic aid. The stimulator, with controls to adjust amplitude only (50 mA), adapts chosen stimulation sequences to the walking rate of a patient. Pulse duration (50-500 microseconds), frequency (5-120 Hz), shape (symmetrical biphasic, monophasic), stimulation sequences (16 stride segments) and their cycle (2-12 sec), and right/left foot-switch choices are selected for each patient and programmed into a separate unit. The programming unit also statistically processes the foot-switch data collected by the stimulator. The device was evaluated with regard to the programmable parameters, effectiveness during gait, and feasibility in clinical use. It was applied to 11 stroke patients and 10 brain injury patients during gait, stimulating 22 combinations of peroneal nerve and hamstring, quadriceps, triceps brachii, and gluteus maximus muscles. Forces on both feet, equinovarus, knee extension and hyperextension, elbow flexion, and hip extension were corrected. Selection of the stimulation sequences, their adaptation, range of pulse duration, and valid statistics were verified. Improved forces and joint angles were recorded together with significant changes in the stride time, length, and velocity by the stimulation.


A human factors approach to adapted access device prescription and customization. Adapted access device prescription and customization is often a lengthy and cumbersome process. To date, few objective procedures are available to assist in the prescription process. Rather, clinician and client rely on a trial-and-error approach that is often severely constrained by the size of their adaptive device collection as well as the extent of clinical expertise. Furthermore, the large number of available options and lack of information delineating the mechanical and physical characteristics of these devices means that therapists must take time away from direct clinical contact to probe each adaptation in detail. There is available in the human factors domain a body of literature that is highly relevant to adapted access. Of particular interest are the studies that have addressed issues related to the suitability of standard and alternative input devices in terms of task productivity (via improvements in input speed, accuracy, and endurance), and their ability to minimize the risk of acute and chronic work-related dysfunction. This paper aims to consider the relevance of human factors research for physically disabled individuals. Three human factors issues--digit travel, digit loading, and device positioning--have been selected as representative of factors important in the configuration of adapted access devices.


Automated fabrication of mobility aids (AFMA): below-knee CASD/CAM testing and evaluation program results. In 1988 the Department of Veterans Affairs Rehabilitation Research and Development Service, under the directorship of Margaret J. Giannini, M.D., began a nationally directed computer-aided design and computer-aided manufacturing (CAD/CAM) research program for the Automated Fabrication of Mobility Aids (AFMA). Under this program CAD/CAM research and development centers were established at the Prosthetics Research Study in Seattle, WA; at Northwestern University and the VA Lakeside Medical Center in Chicago, IL; and at the VA Medical Center and New York University Medical Center in New York, NY. These three centers conducted a collaborative program: (a) to introduce CAD/CAM technologies to prosthetists, physicians, therapists, and rehabilitation health care professionals in the United States; (b) to evaluate the feasibility of using CAD/CAM systems in clinical prosthetics settings; (c) to test and evaluate the University College London-Bioengineering Center's and the University of British Columbia-Medical Engineering Resource Unit's respective systems for the computer-aided design and computer-aided manufacture of prosthetic sockets (CASD/CAM) for below-knee amputees; and, (d) to obtain quantitative data for refinement of the CASD/CAM systems tested, and for the development of new, enhanced, more efficacious, and expedient systems.


Comparison of signal-to-noise ratio of myoelectric filters for prosthesis control. A comparison of signal-to-noise ratios and rise times was performed on several myoelectric filters used for muscle-force estimation and prosthesis control. Linear, averaging, and adaptive filters were compared using single as well as multiple electrode pairs (spatial filtering). The filters were matched for having the same rise time (0-95%) and the signal-to-noise ratios were measured off-line using the same myoelectric signal recording. The linear filter was a low-pass filter with a time constant of 80 ms. The averaging filter had an averaging time of 250 ms. The adaptive filter was the same as is used in the Utah Artificial Arm. The adaptive filter varied its time constant according to the rate of change of the signal mean. If the rate was high, the time constant was set low. If the rate was low, the time constant was set high. Spatial filtering is where the myoelectric signals from four cutaneous sites over the same muscle were summed, that is, spatially filtered, and the resultant signal was smoothed by the linear, averaging, or adaptive filter. Significant improvement in the signal-to-noise ratio has been shown over conventional linear or averaging filters when using spatial and adaptive filtering, both when used separately and when used together.


Cementoblastoma and osteoblastoma: a comparison of histologic features. Three cases of cementoblastoma (CB) and three cases of osteoblastoma (OB) were histologically compared. The aim of the study was to investigate whether CB and OB are different in other aspects than being connected with a tooth. CB cases were the following: maxillary lesions in a 23-year-old woman and a 22-yr-old man and a mandibular lesion in a 28-yr-old man. In one case the tumor was fused to the roots of two teeth. Of the OB cases, one occurred in the mandible of a 27-yr-old man, one in the ankle of a 19-yr-old male and one in the thoracic vertebrae of a 27-yr-old man. Histologically, CB and OB had the same appearance including peripheral spiculae rimmed by swollen blasts. This histologic similarity between OB and CB indicates that the diagnosis CB should not be made unless the lesion is connected with a tooth.


Enamel ultrastructure in pigmented hypomaturation amelogenesis imperfecta. Hypomaturation amelogenesis imperfecta (AI) is a hereditary condition of enamel that is presumed to result from defects during the maturation stage of enamel development. This study characterized the enamel ultrastructure and enamel crystallite morphology, as well as the distribution of organic material in enamel affected with pigmented hypomaturation AI. Enamel exhibiting autosomal recessive pigmented hypomaturation AI was sectioned or fractured and examined using light microscopy, scanning electron microscopy and transmission electron microscopy. Enamel samples were treated with 30% NaOCl or 8 M urea to remove organic components and determine the effect of deproteinization on crystallite morphology. These were compared with untreated normal enamel samples. The enamel crystallites in hypomaturation AI exhibited considerable variability in size and morphology. Examination of deproteinized tissue indicated that the AI crystallites had a thick coating, presumably of organic or partially mineralized material, which was not visible in normal enamel. The results of this investigation provide further evidence that hypomaturation AI is associated with the retention of organic material that is most probably enamel protein. Enamel protein retention is likely to be involved in the inhibition of normal crystallite growth resulting in the morphological crystallite abnormalities associated with this disorder.


Growth hormone regulates nucleolar organizer regions during odontogenesis in the rat. Nucleolar organizers are major sites of ribosomal RNA synthesis and provide an index of transcriptional activity. In order to further define growth hormone actions on nucleolar organizer regions in tooth forming cells, hypophysectomized rats treated with growth hormone for 4 and 24 h, hypophysectomized and sham-operated animals were used. After demineralization and standard paraffin embedding, longitudinal sections of maxillary incisors were stained by a silver stain technique to reveal nucleolar organizer regions. The area of these regions per nucleus was measured using a modified microdensitometer. Analyses of variance of the resulting data showed that preameloblasts and preodontoblasts have greater silver stained nucleolar organizer region values than ameloblasts and odontoblasts. Hypophysectomy reduced and growth hormone partly restored the level of nucleolar organizer regions in preameloblasts and preodontoblasts, but not in mature ameloblasts or odontoblasts. In the case of the younger preameloblasts and preodontoblasts, the effect of growth hormone was seen within 4 h of growth hormone injection. In conclusion, rRNA synthesis, as revealed by the specific silver staining of nucleolar organizer regions in tooth forming cells, appears to be regulated by growth hormone over a relatively short time frame.


Odontogenic myxoma: histochemical and ultrastructural study. Three cases of odontogenic myxoma are presented, two of which were located in the mandible and one in the maxilla. All cases demonstrated similar morphology by light microscopy. Immunohistochemical studies demonstrated positive reaction with antibodies to vimentin and actin, and negative reaction to antibody to S-100 protein. A 127-day-old human tooth bud was used as a control. The ultrastructural features performed on Case 3, when combined with the immunohistochemical findings suggest that the cells comprising odontogenic myxoma are of myofibroblastic origin.


Expression of p53 mutant nuclear phosphoprotein in oral carcinoma and potentially malignant oral lesions. An immunohistochemical study of primary oral squamous cell carcinomas (n = 37) with a monoclonal antibody (PAb 1801) specific to p53 antioncogene product demonstrated nuclear overexpression of the mutant protein in 35% of cases. Those positive included carcinomas without deep invasion suggesting that p53 mutation may occur in the early stages of progression of a malignancy. This is supported by the observation that mutant protein was detectable in limited amounts in 2 cases of oral mucosal dysplasia (n = 12). None of the normal or reactive oral mucosal tissues (n = 17) were positive for p53. The presence or absence of p53 was not correlated with the site of the lesion or its degree of differentiation. Our data suggest that p53 gene mutations are commonly involved in oral cancer but are neither sufficient nor necessary for the development of malignancy. Nevertheless, as this mutation is the commonest genetic change described so far in cancers in white caucasoids, it is possible that its presence can be used as a marker of risk in a high proportion of malignant and potentially malignant oral lesions.


Major recurrent oral ulcers in AIDS: report of three cases. We report the cases of three AIDS patients who developed major recurrent oral ulcers with severe odynophagia and weight loss. The patients were treated successfully with systemic steroids. Within the first week of prednisone therapy (40 mg/day), the symptoms improved and the lesions entirely healed. We suggest, on the bases of recent literature, that superantigens and the cytokine network could be involved and they should be considered in the immunopathogenic mechanisms of this type of ulcers.


Ehlers Danlos syndrome type I with novel dental features. The clinical, radiographic and histologic findings are described in two cases of Ehlers Danlos Syndrome Type I with novel dental features. Defective dentinogenesis principally affecting the mandibular incisors result in aplasia or hypoplasia of root development predisposing to localized periodontal disease. A striking radiographic appearance with a bulbous enlargement of the roots together with pulp stones is seen in other teeth. 'Giant channels' and vascular inclusions resembling 'intermediate cementum' are prominent within this area. No evidence of Type III procollagen or collagen was detected with indirect immunofluorescence. It is suggested that an inherited collagen abnormality in a component common to dentin, skin, ligament and tendon probably explains both EDS I and the dentin dysplasia.


Infantile osteopetrosis: a case report on dental findings. In this paper we have described the case of a 7-yr-old Moroccan osteopetrotic boy, who had received a bone marrow transplant (BMT). He was transplanted from his older brother and, despite immunosuppressive therapy, developed chronic graft-versus-host disease and was placed on corticotherapy. Seven months after the bone marrow transplant, graft versus host disease (GVHD) was stabilized, but corticotherapy had inhibited growth. There was evidence of normalizing bone, his hearing was better but he had not recovered vision. Dental findings before the bone marrow transplant revealed some missing teeth, failure of teeth to erupt and decayed teeth but no enamel hypoplasia. The patient had developed one carious lesion on one unerupted tooth: bacteria seem to have found a way through the gubernaculum dentale. The scanning electronmicrographs showed decayed tooth and tissues fitted into each other. Since the bone marrow transplant, no tooth has erupted. We think that, in this case, failure of tooth eruption would be the sign of osteopetrosis.


Hypophosphatasia: a family study involving a case diagnosed from gingival crevicular fluid. Hypophosphatasia is an inherited disorder characterized by defective mineralization of the skeletal and dental structures of the body and deficient liver/bone/kidney alkaline phosphatase (L/B/K ALP) activity. There has been a tremendous advance in our knowledge of this condition over the last decade due to the advent of highly specific DNA probes and novel microanalytic techniques. The purpose of this paper is threefold: to review the dental aspects of current literature about this rare condition; to present a case (and family study) that was diagnosed in a 5-yr-old boy from 0.14 microliters of gingival crevicular fluid, using a new ultrasensitive chemiluminescent assay for the enzyme alkaline phosphatase; and to provide strong evidence for an autosomal dominant mode of inheritance.


Therapeutic advances in ulcerative colitis. Ulcerative colitis is an inflammatory condition that requires individualized and innovative therapy for each patient depending on the symptoms, location, severity, and chronicity of the disease. It is most often a chronic illness that requires modification in treatment as the stage of the disease changes. Systemic and rectal aminosalicylates (sulfasalazine, mesalamine, olsalazine and corticosteroids) remain the most useful therapeutic agents. Rectally administered mesalamine and the forms of oral mesalamine appear to have significant advantage over sulfasalazine dosage forms. Future clinical usage and scientific study will determine the place of these newer agents among other medical therapies and the surgical management of ulcerative colitis.


Implant rehabilitation in Erdheim-Chester disease: a clinical report. Successful osseointegration of endosseous titanium implants is thought to be dependent upon close apposition of bone to the implant surface. The integration of implants in this patient was achieved despite the lipid-laden histiocytic infiltration of the bone marrow. Presumably, enough unaffected stromal cells were present to allow sufficient bone formation for osseointegration of the implant fixtures. This result invites speculation regarding both the mechanism of osseointegration and the minimum surface area of bone-implant interface necessary for achieving and maintaining osseointegration of titanium implants. This patient is periodically examined to determine if the loaded fixtures will remain clinically immobile for a prolonged period.


Physical properties and repair bond strength of direct and indirect composite resins. Use of composite resins now includes indirect curing methods. Surface chemistry, repair bond strength, plus location of failure and five physical properties of two direct and three indirect composite resins were determined. There were statistically significant differences in flexural strength of materials and in hardness values. Repair bond strength failures were not significantly different; failures occurred primarily at the interface. Multiple internal reflection spectroscopy confirmed the presence of unpolymerized material after cure in all products. Indirect cure of the direct composite resin increased the degree of cure.


Light-cured resin for post patterns.

Light-cured resin for post patterns. A method of using light-cured acrylic resin as an alternative to the use of chemically-cured acrylic resins with elastomeric impressions for direct post patterns is presented. The GC Unifast LC acrylic resin is a powder/liquid type resin cured by exposure to visible light. The polymerization process has four stages before final curing: slurry, stringy, dough-like (plastic), and rubber-like (elastic). Advantages over current direct and indirect procedures include ease of manipulation of the material and no change in laboratory handling procedures. While in the dough-like state, the material can be contoured. In the rubber-like state, it is flexible to disengage from minor undercut areas.


Effect of core materials on stress distribution of posts. Severely damaged endodontically treated teeth require the use of a post and core for the retention of the restoration. The choice of material for a post and core and their stress-producing characteristics must be considered by the clinician. Two-dimensional photoelastic analysis of birefringent models was used to investigate the influence of different core materials on the stress distribution of nonthreaded cylindrical posts. Cast posts and cores and prefabricated posts with amalgam and composite resin cores were compared with posts without cores at installation and under two loading conditions. The findings indicate a significant difference between posts with and without cores. It appears that the stiffer core materials can shift the load from the apex to the coronal region.


Effects of posts on dentin stress distribution in pulpless teeth. A finite element analysis was carried out to study the roles of posts in reducing dentin stress in pulpless teeth. Two-dimensional plane strain models of the midlabiolingual section of a human maxillary central incisor were first analyzed. The results showed that the gold alloy post reduced maximal dentin stress by as much as 30%. However, the integrity of the dentin was compromised and the effects of the post were likely to be exaggerated in such models. In an effort to correct for these problems, plane stress models with side plates and axisymmetric models were analyzed. Posts were found to reduce maximal dentin stress by only 3% to 8% when the teeth were subjected to masticatory and traumatic loadings in these latter models. Although posts reduced maximal dentin stress by as much as 20% when the teeth were loaded vertically, teeth such as incisors and canines normally are not subjected to vertical loadings. Thus the reinforcement effects of posts seem to be doubtful in these teeth.


Root fracture in endodontically treated teeth related to post selection and crown design. Standardized plastic analogues simulating an endodontically treated maxillary central incisor root were used to investigate the resistance to root fracture in endodontically treated teeth. Three different post and core systems were used: (1) cast post and core, (2) Para-Post Plus post, and (3) Flexi-Post post. The core build-up material selected in this study was Ketac Silver material, after which a crown preparation was made on each analogue. Two types of preparations were used: a wide chamfer margin (butt-joint) and a wide chamfer margin with a 1.0 mm circumferential bevel. An overcasting was fabricated and was permanently cemented on each preparation. Assemblies were subjected to an increasing lingual oblique force until fracture occurred. Results were tabulated using the analysis of variance (F test) and Student's t test. Beveled preparations with a concomitant final restoration provided a significant increased resistance to root fracture. Furthermore, vertical fracture occurred twice as often with nonbeveled preparations.


The retentive and stress distributing properties of split threaded endodontic dowels. A threaded, parallel-sided endodontic dowel that has a longitudinal split was tested to determine its retention and stress distribution properties. Photoelastic stress analysis revealed high installation stresses unless the dowels were counterrotated. Axial loading created stresses at the threads, with elevated coronal and apical stresses. Even higher coronal stresses were recorded with inclined loads, and shorter dowels generated greater stresses than longer dowels. The retentive values were generally lower than those in comparable studies.


Evaluation of the fracture resistance of a wrought post compared with completely cast post and cores. The intraradicular fracture of a post and core presents a difficult and often unrestorable situation. Attempts to prevent this problem involved the use of materials with increased physical properties. The use of a preformed wrought post with a core cast to it may provide a more fracture-resistant foundation. This investigation compared a commercially available noble alloy-wrought post that had a gold core cast to it with completely cast specimens from three different alloys. A standard pattern was designed to simulate a post and core that would be used in a tooth of limited length and canal space. Patterns were cast and fixed to custom holding devices. Each specimen was subjected to a shearing force until catastrophic failure in a universal testing machine. Significant differences were noted among the groups.


Cement luting thickness beneath porcelain veneers made on platinum foil. Porcelain laminate veneers were made using a platinum foil matrix and were subsequently cemented to mandibular anterior Cymel teeth. Cement film thickness was measured in six predetermined locations. Repeated measures analysis of variance and single degree of freedom contrasts delineated a significant difference between marginal openings at the incisal edge where foil is folded and in four of the other vertical areas (132 versus 74.1 microns). Marginal cement film thickness of veneers made on platinum foil is less than that reported for veneers made on a refractory investment.


An evaluation of smear layer with various desensitizing agents after tooth preparation. According to hydrodynamics, any agent blocking the dentinal tubules reduces the flow of fluids and diminishes hypersensitivity. The properties of the desensitizing agents that sponsor tubular occlusion and the barrier efficiency resulting from the interaction of the smear layer with test materials were examined with the scanning electron microscope and energy-dispersive x-ray microanalysis. Selected dentinal desensitizing was accomplished with burnishing procedures, cavity varnish, calcium hydroxide, and topical fluoride. Subjective evaluations were also recorded clinically after tooth preparation. This investigation indicated that the smear layer did not protect against zinc phosphate cement, and that cavity varnish prevented the formation of the smear plugs. The smear layer and plugs were basically composed of calcium and phosphorus, the major ingredients of dentin.


Mechanical properties of heat-treated composite resin restorative materials. Clinical methods for heat treating composite resin restorations have been developed. In this investigation, the effect of heat treatments on the diametral tensile strength of composite resin was determined. The composite resin restorative materials were selected according to the manufacturers' suggested use for anterior or posterior teeth, filler particle composition, and light-cured or chemical polymerization. Samples were prepared according to American Dental Association specification No. 27, and heat treatments were accomplished with a Coltene DI 500 oven for curing at approximately 120 degrees C for 7 minutes. Heat treatment substantially increased the diametral tensile strength tested, with the exception of the anterior hybrid particle (p less than 0.05). Composite resins with fine-particle inorganic fillers were significantly stronger than hybrid and microfilled composite resins.


Properties of test metal ceramic titanium alloys. Four test alloys were prepared using a high frequency centrifugal casting machine and a ceramic crucible for the development of titanium bonding alloys that can be cast in the ordinary atmosphere. Of these alloys, 10.06% Ti, 78.79% Ni, 9.02% Pd, 1.77% Sn and 9.91% Ti, 78.56% Ni, 9.07% Pd, 1.86% Sn, 0.65% Ir could be cast by the conventional high frequency centrifugal method; however, 89.18% Ti, 8.75% Ni, 1.03% Pd, 0.28% Sn and 89.81% Ti, 8.15% Ni, 1.01% Pd, 0.18% Sn, 0.67% Ir could be cast only by the argon are melting method. The alloys 10.06% Ti, 78.95% Ni, 9.02% Pd, 1.77% Sn and 9.91% Ti, 78.56% Ni, 9.07% Pd, 1.86% Sn, 0.65% Ir showed excellent physical and mechanical properties and bonding strengths, surpassing those of the commercial alloys TPW and Unimetal. Concerning the elution of component elements, the amounts of titanium eluted from these alloys were far smaller than those from pure titanium or a Ti-6Al-4V alloy, and nickel elution, which has become an issue in relation to metal allergy, was almost nil in contrast to Unimetal (Ni-Cr alloy). The alloy 9.91% Ti, 78.56% Ni, 9.07% Pd, 1.86% Sn, 0.65% Ir showed properties that indicated its favorable use as an alloy for the bonding of dental porcelain.


Use of plastic bar molded casting in the modification of variably expanding investment to compensate for casting shrinkage of nickel-chromium alloy. Trial plastic bar molded castings were compared for accuracy with cast crowns by means of a nickel-chromium alloy, which was used to establish the liquid density of variably expanding investments. The plastic bars were invested to evaluate the change of expansion rate in a wide range of six liquid densities from 0% to 100%, and the distances between the sections were measured before and after casting. Wax crowns were cast to obtain a more detailed relation around 0% expansion at seven liquid densities, and the gaps between the base of the die and the margin of the crown were measured before and after casting. The expansion rates of both castings were calculated and thus were proportional to the liquid density; both regression curves indicated high correlation coefficients. As a result of the statistics of the Student's t-test, the difference between the two methods was not significant. The trial plastic bar was useful in establishing the variably expanding investment for precise casting of artificial crowns.


A mathematic model of occlusal adjustment. A mathematic algorithm was developed to calculate mandibular repositioning resulting from occlusal equilibration. A formula to determine the amount of tooth reduction necessary for the adjustment also was derived.


Effect of seating force on film thickness of new adhesive luting agents. This study examined the effect of seating force on the film thickness of new adhesive luting agents. The method was in compliance with American National Standards/American Dental Association Specification No. 8 for zinc phosphate cement. The materials tested were zinc phosphate cement, glass ionomer cement, polycarboxylate cement, and a resinous cement with a dentinal bonding agent. All materials were manipulated exactly as described in the manufacturer's instructions, and an electronic gauge with an accuracy of 0.5 micron was used. Each class of material was measured 10 times at six different seating forces. Analysis of variance and multiple comparisons testing disclosed that the seating force and class of material strongly influenced the film thicknesses of luting agents. A mathematical model describing the response of zinc phosphate cement within the range tested was reported.


Effect of surface roughness and cement space on crown retention. The effects of varying luting agent space and internal surface roughness with different types of cores and cements were studied. One hundred eighty amalgam and 180 composite cores were cemented into standardized stainless steel retainers. Cores and retainers were divided into 12 groups according to core type, core diameter, and retainer roughness. Each group was further subdivided according to cement, A: zinc phosphate (ZOP); B: resin; and C: glass ionomer cement (GIC). Subgroups were divided into thermal-cycled and nonthermal-cycled groups. Thermal cycling was at 5 degrees to 55 degrees C, repeated 500 times. Cores were separated from their retainers with a compression rod in an Instron testing machine at a crosshead speed of 0.02 cm/minute. Results were as follows: Amalgam cores were most retentive. Resin and ZOP cements were equally retentive with amalgam cores, but GIC was less retentive. Resin cores cemented with resin cement were more than twice as retentive than those cemented with ZOP or GIC cements. Retainers with rough internal surfaces were most retentive. A reduced cement space between core and retainer was most retentive. Thermal cycling reduced retention.


Image analysis and occlusion.

Image analysis and occlusion. This study was designed to investigate the measurement of the occlusal contact area (surface) using commercially available equipment and computer programs for image processing and analysis. A stable occlusal record was made using an addition curing silicone rubber putty and was placed on a light source onto which a video camera was focused. This image was digitized and standard thickness records were used to calibrate the appropriate threshold for measurement of contact and near contact surfaces. Differences between individuals and within individuals with and without their partial dentures are large. This method has the potential to be a powerful tool in the study of occlusion.


Comparison of load transfer by maxillary distal extension removable partial dentures with a spring-loaded plunger attachment and I-bar retainer. This study photoelastically compared the stress distribution characteristics of two maxillary bilateral distal-extension removable partial denture designs, one using I-bar retention and the other using a semiprecision spring-loaded plunger attachment. Each prosthesis was subjected to vertical and horizontal extension-base loads. Comparisons were made from photographic recordings of isochromatic fringe distributions. The two retention designs produced comparable stresses with splinting of abutments for the plunger attachment. The attachment-retained prosthesis proved less stable with some loadings. Stress patterns followed three trajectories in the maxilla. A basis for stress distribution comparisons to other maxillary removable partial denture attachments is established.


One-appointment construction of an immediate transitional complete denture using visible light-cured resin. A technique is described for construction of an immediate transitional complete denture in one appointment using self-curing tooth color and visible light-cured resins. Conventional immediate denture therapy may be too prolonged for medically or physically compromised patients. This alternative treatment reduces laboratory, dentist, and patient time, thereby providing a fast and economical service.


Treatment of edentulous maxillae with osseointegrated implants. Edentulous maxillae can be restored with implant supported fixed restorations containing denture teeth on a metal framework, implant-retained removable overlay prostheses, or porcelain fused-to-metal fixed prostheses. Esthetics and hygiene access are two important factors in determining the restoration best suited for each patient. Treatment planning considerations and treatment procedures for the various techniques are discussed.


Comparative implant research in dogs: a prosthodontic model. One-hundred twenty endosteal dental implants were inserted bilaterally in the mandibles of 30 adult mongrel dogs after bilateral extraction of all premolars. The 120 implants were evenly divided into one- and two-stage systems and included ceramic and titanium cylindrical root-form implants and titanium blade implants. The research design of this investigation divided the 30 animals into 10 groups of three dogs. This article describes an animal model that is useful in evaluating dental implant designs and compares the results with those from humans. In particular, this article delineates the prosthodontic approach appropriate for this model using one- and two-stage titanium implants. Rexillium alloy fixed prostheses were placed on 32 endosteal implants and 16 natural mandibular molar teeth. The implants and prosthetic components of the Sterio-Oss implant system were used. All prostheses are functional with minimal maintenance. To date, after 1-year of follow-up, none of the implants have been lost and none of the fixed prostheses have required recementation or maintenance other than normal hygiene. Histologic and survival data as well as results with other implant systems will be presented in other reports.


Effects of osseointegrated implants on psychological and social well-being: a literature review. This article considers three research topics on the social and psychologic aspects of osseointegrated implants. First, the motivations of patients who enter therapy are described. Second, research studies on the psychologic effects of dental implants are critically examined. Although these studies provide consistent evidence in support of osseointegrated implants, there are many issues that make interpretation of results problematic. Finally, some suggestions for future research are made.


Effects of environmental factors on maxillofacial elastomers: Part II--Report of survey. Part II of a four-part report presents an international survey that was conducted to determine the most frequently used materials in the fabrication of facial and somatoprostheses. The survey also solicited information about advantages and disadvantages, methods of coloring, and the perceived properties of an "ideal" material. The results of the survey indicated that the majority of prosthodontists and prosthetists are using room temperature-vulcanized silicone products, intrinsically colored with dry earth pigments or artist's pigments. The need for further research in materials for external prostheses was clearly indicated.


The mandibular swing-lock complete denture for patients with microstomia. Regardless of cause, the treatment of an edentulous patient with microstomia is difficult and often ingenious. Prosthodontic treatment modalities previously described are reviewed. A new type of prosthesis, the collapsible mandibular swing-lock complete denture, is introduced. The prosthesis incorporates a cast cobalt-chromium framework with a lingual hinge and a conventional labial swing-lock. This combination allows the prosthesis to be collapsible while maintaining structural durability. Advantages include ease of insertion and removal while providing maximum coverage for support, retention, and stability. A stepwise technique for the clinical and laboratory phases is described.


A multivariate study of patients with temporomandibular joint disorder, atypical facial pain, and dental pain. The multifactorial nature of oral and facial pain was investigated by the collection of clinical and psychologic data from 312 patients with either dental pain, temporomandibular joint disorder, or atypical facial pain. Significant differences between the groups in gender and age distribution, muscle and joint pain, radiographic joint changes, number of remaining teeth, pain duration, and aspects of the patients' perception of pain were evident. In addition, discriminant function analysis clearly differentiated between the three groups on the basis of both clinical and psychologic variables, emphasizing the multifactorial nature of oral and facial pain.


Comparison of four different methods of evaluation on axially corrected tomograms of the condyle/fossa relationship. One hundred temporomandibular joints of 50 dry skulls were used to determine whether there was a statistically significantly difference among four different techniques that were employed to assess the condyle/fossa relationship on axially corrected tomograms. A two-way analysis of variance was performed and the results indicated that: (1) a highly significant difference in the condyle/fossa relationship existed (p = 0.002) among the various skulls and (2) no significant difference existed between the four techniques employed to assess the condyle/fossa relationship (p = 1).


Evaluation of variables associated with the transverse horizontal axis. The effect of transverse horizontal axis deviations on the vertical and horizontal orientation of maxillary and mandibular members was investigated on a laboratory articulator model. Twelve axis deviations (+30, +25, +20, +15, +10, +5, -5, -10, -15, -20, -25, and -30 mm groups) within a 55 mm dimension model were evaluated. Three trials at each transverse horizontal axis deviation demonstrated significant changes in maxillomandibular orientation after mounting the mandibular member with a standardized intermember mounting record. A linear regression analysis produced an equation for predictive interpolation of anterior-posterior shift as a result of axis deviations from +30 to -30 mm.


Spacer made from a visible light-cured resin for processing denture soft liners. When soft lining materials are used in complete dentures it is important to control their thickness and increase the probability of their staying in the denture base. A spacer made of light-curing denture base material makes it possible to do both of these things. The denture base resin is packed against the hard light-cured spacer and can be partially cured. The cured spacer will not flow or be displaced and can be easily removed to allow an even space for packing the soft lining material.


A flasking technique for microwave processing of silicone prostheses. Polyvinylchloride plumbing parts provide a readily available source of material to use in making facial prostheses. Inexpensive pipe fittings (end cap attachments and closet flanges) can be combined to provide a durable container for stone molds that can be tightened in a strong curing press. The entire unit can be cured in a microwave oven in 30 minutes.


Making a coping for an esthetic veneer crown. Esthetic veneer crowns should be waxed to full contour before the veneer surface is cut back. This procedure ensures that patterns and metal copings will have the proper contours. A technique is described for making a coping that has an ideal thickness of 0.3 to 0.5 mm, that is stable, and that is unlikely to fracture.


A soft tissue simulated cast for implant prosthesis. A master cast that simulates the mucosa around implant fixtures and abutments facilitates implant prosthesis fabrication. It is helpful if this simulation is not altered during laboratory procedures. A technique is described for a master cast that includes a removable mucosal component. This technique can be applied when either implant or abutment analogs are positioned in the cast.


Protecting the finish of stone dies during trimming. This procedure is quick, easy, and inexpensive. It prevents damage to the die during trimming and does not alter the integrity of the die.


Duplication of interim speech aid for definitive impression tray fabrication. A wax tray is stable and easily relieved if overextended. Unusual tray undercuts or angles needed for the partial resection patient need not be eliminated before the impression procedure. Relief of these undercuts is necessary with acrylic resin trays to ensure separation from the final stone cast. Because the wax tray is separated easily from the prosthesis during the boil-out, it is not necessary to "burn" or grind acrylic resin from the framework. The tray shape is duplicated from the existing interim prosthesis on the nasopharyngeal and oropharyngeal side. An arbitrarily shaped acrylic resin tray may be grossly overextended and require time-consuming clinical adjustments. An underextended tray on the nasopharyngeal side will not carry or support the impression material around or through the residual soft palate remnant. A tray that closely approximates the final prosthesis will allow use of a tissue conditioner final impression without need for border molding (Fig. 2). Duplicating the oropharyngeal side of the interim speech aid duplicates the previously established plane that is compatible with the tongue. The author has used this technique successfully for eight total and five partial soft palate resections. A cleft palate speech aid prosthesis has also been made with this technique.


An experimental porcelain repair system evaluated under controlled clinical conditions. Twenty metal ceramic crowns on upper premolars in 12 patients were purposely fractured before seating with temporary cement. The fractured crowns were repaired in situ with an experimental porcelain repair system. The initial results were satisfactory both esthetically and functionally. However, only 50% of the repairs were intact by the end of the 12-month follow-up period. The system is considered to be suitable only for intermediate repairs of metal ceramic crowns that are in occlusal contact.


Polyvinyl siloxane impression materials: a review of properties and techniques. Polyvinyl siloxane impression materials have been shown to have excellent properties as impression materials; however, they are sensitive to manipulative variables. Several methods of using very high viscosity (putty) materials to form "trays" to obtain uniform bulk of the wash impression are described, and the disadvantages of each of these techniques is pointed out. It is recommended that for best results acrylic resin custom trays should be used routinely. The interaction of polyvinyl siloxane materials with latex products is also discussed and problems that this inhibition can cause are stated. Suggestions to avoid this interaction are outlined. One of the disadvantages of the impression materials is that it has a relatively short working time. Refrigerating the material will increase working time without affecting accuracy.


Effect of fluoride varnish on the retentive strength of provisional crowns luted with various temporary cements. The retention of temporary crowns was studied with the use of a fluoride varnish (Duraphat) combined with various temporary cements. The mixture of Duraphat varnish and cement improved retention, with the exception of Opotow cement. Applying Duraphat varnish to the tooth surface before cementation enhanced the retentive strength of Tempbond, weakened the retention of Freegenol, but had no effect on Opotow cement. A "transfer effect" was observed, inasmuch as the Duraphat varnish encouraged adherence of the cement to the tooth structure rather than to the temporary crown.


Use of luting agents with an implant system: Part I. When removal of the provisionally cemented superstructure from a cemented abutment becomes necessary, the retentive strengths of the abutment/fixture and superstructure/abutment luting agents become important considerations. This study compared the retentive strengths of castings cemented to machined titanium implant abutments and to a human premolar with three provisional luting agents. Also tested were the retentive strengths of cast noble metal implant abutments cemented into titanium fixtures with three permanent luting agents both dry and after storage in 0.9% physiologic saline for 30 days at 37 degrees C. No significant differences (alpha < 0.05) were noted in retentive values between the cemented castings on the titanium abutments and the natural tooth. The Temp Bond zinc oxide-eugenol luting agent exhibited a lower mean retentive strength than the IRM reinforced zinc oxide-eugenol and Life calcium hydroxide luting agents. Ketac Cem glass-ionomer cemented abutments that were stored in saline exhibited a significantly higher mean retentive strength than abutments cemented with either Core Paste or Resiment resin luting agents. On the basis of results from this study, it may be concluded that superstructures provisionally cemented with Temp Bond, IRM, or Life luting agents may be removed from implant abutments without disturbing the abutment/fixture or implant bond.


Change in occlusal height resulting from placement of pit and fissure sealants. This in-vitro study was done to identify the amount of change in occlusal height resulting from standard sealant application technique and to determine whether this change was uniform for both a filled and an unfilled sealant material. Twelve dental hygienists experienced in sealant technique each applied 10 filled sealants and 10 unfilled sealants in standardized artificial teeth mounted in a dentiform and mannikin setup in a dental unit. The teeth were measured with a digital caliper before and after sealant placement. Measurements were from a predetermined point at the apical area of the teeth to the depth of the central fossa. For the sample of 240 teeth, the mean sealant thickness was 0.43 +/- 0.20 mm. When the data for the filled and unfilled sealants were examined separately, the means were 0.47 +/- 0.23 mm and 0.38 +/- 0.16 mm, respectively. A t-test indicated a significant difference at p < 0.001. Analysis of variance revealed significant interoperator differences in sealant thickness (p < 0.01).


Alterations in human enamel surface morphology following vital bleaching. Extracted intact human teeth (n = 4) were treated for 30 days by three protocols: Home 1 (Proxigel, n = 4) for 8 hours daily, Home 2 (White & Bright, n = 4) for 24 hours with 3 minutes of stannous fluoride gel, or an Office protocol (n = 4) using 30% hydrogen peroxide (Superoxol) warmed by a high-intensity light while the controls remained untreated. "Home" bleaching agents contain approximately 10% carbamide peroxide. After treatment, the coronal surfaces were examined with a scanning electron microscope (SEM) at 2000 power magnification, and the surface topography was measured by a profilometer. The SEM photomicrographs of the controls and office-treated groups were similar to previously reported descriptions, while the home bleached surfaces appeared similar to each other. Profilometric analysis was used to examine surface roughness and surface waviness. Mean surface roughness in microns was: control, 1.9; Home 1, 0.6; Home 2, 0.9; and Office, 0.6. Surface waviness was ranked control > office > Home 1 = Home 2. Enamel surface alterations were evident after the three bleaching methods. The differences between the office and home-treated surfaces were unrelated to the pH of the bleaching agents.


Epinephrine absorption from commercial gingival retraction cords in clinical patients. Absorption of epinephrine from commercial gingival retraction cords was measured in vivo under clinical conditions. The amount of epinephrine absorbed was estimated by measurement with fluorospectrophotometry of the amount of dl-epinephrine remaining in the cords after they were removed and subtracting this value from the dl-epinephrine concentration in matching control cords. All cords lost substantial amounts of epinephrine while in the sulcus, with individual losses ranging from 64% to 94%. An average 71 micrograms of l-epinephrine was absorbed per inch of two-ply cord, and extreme variability in the dl-epinephrine concentration for individual segments of commercial cord was noted. In addition, the cords did not contain the concentration of epinephrine (500 micrograms/inch) listed on the package label but instead had a mean dl-epinephrine concentration of 225.5 micrograms/inch.


Postcementation marginal fit of a new ceramic foil crown system. The in vitro marginal fit of a new foil crown was investigated. Ten standardized polycarbonate master dies filled with 30 wt% carbon having a 90-degree butt joint margin were used to evaluate the marginal fit of Sunrise porcelain foil crowns. The crown specimens were made on stone dies and treated with three coats of die spacer. After fabrication, they were adjusted, cemented with zinc phosphate cement to their respective master dies with 5 kg loading for 10 minutes and stored in water. A Gaertner traveling microscope was used to measure the marginal fit of each specimen. Readings were recorded at five locations randomly marked but equally dividing the margin on each crown, and the overall mean for the crowns was then calculated. The results from the 50 areas revealed a mean marginal discrepancy of 25.3 microns, and this compared favorably with the discrepancies reported for other ceramic crown systems.


Transitional use of a tube/sleeve dowel on endodontically treated canines. This technique affords a simplified alternative to more complicated and expensive treatment of periodontically compromised teeth. It provides the patient with an extended-term prosthesis attached to a single or multiple retained canine. A disadvantage of this technique is that poor hygiene may result in caries or further periodontal breakdown. The internal liner of the cemented tube/sleeve will accumulate food particles if the patient does not keep the prosthesis in place during all times of food ingestion and does not periodically irrigate the internal tube/sleeve.


The effects of cold treatment on the physical properties of stainless steel and titanium alloy endodontic posts and instruments. This study determined whether cold treatment at -96 degrees C affected the mechanical properties of different compositions and sizes of Flexi-Post systems, various sizes of dental reamers, and external wrenches. The experiment was divided into eight groups. The four control groups were untreated and consisted of (1) 50 stainless steel posts, (2) 40 titanium posts, (3) 50 stainless steel reamers, and (4) 10 stainless steel external wrenches. The four experimental groups were cold treated once and twice and included (1) 100 stainless steel posts, (2) 80 titanium posts, (3) 100 stainless steel reamers, and (4) 20 stainless steel external wrenches. The bending or breaking forces were tested on a universal testing machine. Stainless steel Flexi-Post dowels, stainless steel reamers, and external wrenches all showed a significant (ANOVA) (p < 0.05) increase in strength as a result of the single and double cold treatment. Titanium posts showed no strength increase following a single cold treatment, while they were weakened by a double cold treatment.


Influence of circadian periodicity on reproducibility of centric relation records for edentulous patients. Complete dentures were made for 30 edentulous patients. The patients were divided into three groups and the dentures were remounted twice on the same day in a Vericheck instrument. The dentures for 10 patients were remounted twice in the morning (AM group), for 10 patients twice in the afternoon (PM group), and for 10 patients once in the morning and again in the afternoon (AM-PM group). Changes in position between the interocclusal records were measured on both the right and left horizontal X and Y axes and the sagittal Y and Z axes. No significant changes were noted when horizontal versus sagittal or right versus left positions were compared, but significant changes were noted between the AM versus AM-PM time groups, and between the PM versus AM-PM time groups.


Load transfer by a maxillary distal-extension removable partial denture with cap and ring extracoronal attachments. This study photoelastically compared the stress distribution characteristics of maxillary, bilateral, distal-extension removable partial dentures retained by light and heavy ERA extracoronal attachments. One prosthesis included supporting rests and the other had no rests. Both designs were tested with and without abutment splinting. The most favorable stress distributions were obtained with light retention elements, supporting rests, and splinting of the abutments. In this configuration the attachment prosthesis compared favorably in stress distribution with the maxillary I-bar retained removable partial denture in a previous study that used a comparable maxillae model.


Force-deformation properties of artificial and natural foods for testing chewing efficiency. The force-deformation characteristics of two artificial test foods (Optosil and Optocal) for measurements of food comminution during mastication were investigated in a bite simulator and compared with those of carrots and peanuts. The influence of cusp geometry was evaluated by use of a flat plate and three cusp forms. The forces at the yield point were lower for Optocal than for Optosil artificial test food. The forces needed for Optocal overlapped those needed for carrots and peanuts. The natural foods showed more variation in the force and percentage of deformation at the yield point than the artificial foods. The artificial foods reflected the differences in cusp form better than did the natural foods. The use of artificial foods fulfills a need for standardization and warrants consideration in studies of mastication.


The effect of removable partial denture framework design on gingival inflammation: a clinical model. A clinical trial using the experimental gingivitis model developed for periodontal clinical research was performed to evaluate the effect of a removable partial denture mandibular major connector design on the surrounding gingival tissues. A comparison of the state of health of adjacent gingival tissues was made between the linguoplate (control) and cingulum bar (test) major connectors. Clinical parameters were recorded in a single-blind crossover experimental gingivitis trial. Subjects were brought to a level of optimal gingival health and then randomly assigned to use one framework design while refraining from any oral hygiene. Measurements were made at 7-day intervals for 21 days. The subjects were returned to optimal oral health and repeated the experimental period with the alternate design. Results showed a greater increase in mean gingival inflammation with the control than with the test removable partial denture, suggesting that the cingulum bar has fewer detrimental effects on gingival tissues than the linguoplate major connector. Results of this study suggest that the experimental gingivitis model can be a useful and valid system for studying the potential effects of a removable partial denture design on surrounding oral tissues.


In vitro evaluation of Candida albicans adherence to soft denture-lining materials. The adherence of Candida albicans to seven commercial soft denture-lining materials was studied in vitro with BCA protein assay reagent. A good correlation was observed between the amount of protein in yeast cells and the number of yeasts (r = 0.993, p < 0.01), and it was revealed that the adherence of C. albicans to bare surfaces of these soft denture-lining materials correlated well with their relative hydrophobic properties (r = 0.905, p < 0.01); thus there was consistency with the thermodynamic theory. These results combined corroborated the accuracy of this method. To know the effect of pellicle on fungal adherence, the adherence of C. albicans to saliva-coated samples was examined. It was revealed that neither the amount of protein adsorbed by substrates nor the adherence of yeast to saliva-coated substrates correlated with the relative hydrophobic properties of these samples, suggesting that factors other than hydrophobic interaction play an important role in the adherence of C. albicans to pellicle-coated soft liners and tissue conditioners.


Generic terminology for endosseous implant prosthodontics. Implant dentistry has become an integral treatment modality in the restoration of the complete and partially edentulous patient. Most practitioners have been educated by manufacturer-sponsored courses oriented to the use of a specific implant system. The ever-increasing number of implant systems has made the names of many implant components product-unique and confusing. Fortunately, a prosthetic continuity exists between most implant systems. A generic terminology for endosseous root-form prosthodontics is presented that allows effective communication between members of the profession.


The three-dimensional bone interface of an osseointegrated implant: a method for study. To clarify the three-dimensional bone structure around a plasma-sprayed hydroxyapatite-coated endosseous dental implant, bone contact with the implant at 75 microns intervals was evaluated. Based on digitized data, three-dimensional graphics of the bone around the implant was clearly shown. These graphics provide adequate information on the bone-implant interface and also suggest development of a realistic finite element model.


Cantilever rests: an alternative to the unsupported distal cantilever of osseointegrated implant-supported prostheses for the edentulous mandible. Mandibular prostheses supported by implants placed between the mandibular foramina restrict the length of the distally cantilevered components to minimize torque-related stress to the supporting implants. Additional posterior implants used as abutments with rigid attachments better distribute occlusal forces and reduce cantilever torque to the anterior implants. Because of the phenomenon of mandibular flexure, these posterior implants could be subjected to stress-induced microdamage to the bone-implant interface. The use of posterior abutments for support of the cantilever without connection reduces the potential hazard of stress-induced microdamage.


Effects of environmental factors on maxillofacial elastomers: Part IV--Optical properties. The optical properties of four currently used and two recently introduced maxillofacial prosthetic materials were evaluated after the materials were subjected to the following seven environmental variables: natural weathering; normal aging; two types of adhesives; two types of cleaning agents; and cosmetics. Optical density and color changes were evaluated. The currently used silicones Silastic 4-4210 and Silastic 4-4515, Medical Adhesive type A material, and polyurethane all showed more changes in color and optical density than the newly introduced silicone A-102 material.


New diagnostic and therapeutic mechanical device. A new device is described that may be used (1) diagnostically to determine the relationship of the occlusion to tenderness in the lateral pterygoid and other muscles of mastication; (2) to relieve ischemic muscle tenderness; (3) to assist in the reduction of articular clicks; and (4) as a positioning device for the registration of physiologic interocclusal relations. The rationale for the causal relationship between the occlusion and lateral pterygoid muscle tenderness is explained.


Biomechanical model of the human mandible: a hypothesis involving stabilizing activity of the superior belly of lateral pterygoid muscle. A new biomechanical analog for the human mandible is proposed. The biomechanics of the human mandible can be explained by a simple support model, where muscular forces are produced by the masseter, medial pterygoid, temporal, and superior lateral pterygoid muscle components, and reaction forces are produced by the occlusal surfaces and condyle. All forces are resolved into components orthogonal and parallel to the temporal articular plane (articular eminence). In this model, one component of muscular forces is parallel to the temporal articular plane. The influence of the inclination of the occlusal plane, the inclination of the temporal articular plane, the position of the resultant of the occlusal reactions, and the relative contribution of the different jaw elevator muscles on the parallel and orthogonal components are evaluated according to a computer model of the system. The muscular force parallel to the temporal articular plane may be produced by the superior lateral pterygoid muscle, which during clenching acts as a stabilizer of the mandibular condyle to prevent posterior dislocation and compression of nonarticular tissues.


Color stability of long-term soft denture liners. The use of resilient denture liners in complete denture construction has become increasingly popular for providing comfort for denture wearers. The primary disadvantage of these materials is that the physical and mechanical properties change rapidly with time in a service environment. The purpose of this study is to evaluate the color stability of five commercially available soft denture liners as a function of accelerated aging. Color measurements were made before aging with a colorimeter and data processor. The samples were then weathered for 100 hours in an accelerated aging chamber in the presence of a xenon ultraviolet visible-light source, an intermittent water spray at 110 degrees F, and 90% humidity. After aging, color measurements were made again and color differences (delta E) were calculated. Results were statistically tested with analysis of variance and Scheffé intervals were calculated at 0.96. It was concluded that accelerated aging can be used to evaluate color stability of soft denture liners.


The facial soft tissue profile of the southern Chinese: prosthodontic considerations. A simple photographic setup was established to produce standardized life-sized black and white prints of Southern Chinese adults. Facial soft tissue profile analysis was performed on 28 men and 31 women aged 19 to 30, dentate Chinese, having class I occlusion and originating from Guangdong province. The facial profile values studied included the profile convexity, the interlabial contour, the nasolabial contour, the columella and upper lip inclination angles to the true horizontal, and the relative positions of upper and lower lips from the Esthetic plane. Data obtained were compared with those from previous Caucasian studies and other accepted empirical values. The lower third of the face presented the greatest ethnic difference: the interlabial contour was more convex and the upper and lower lips were more protrusive among the Southern Chinese. The widely-used standard of a right-angled nasolabial contour proved to be applicable among the Southern Chinese adult males. However, a more obtuse nasolabial angle, almost 100 degrees, occurred among the women.


Making an instrument for smoothing the detailed occlusal anatomy of a wax pattern. A smooth wax pattern is imperative to reduce the polishing time of the subsequent casting. The detailed occlusal anatomy is often the most difficult portion of the wax pattern to smooth. This article describes a procedure for making a device that can be used to smooth the detailed anatomy of a wax pattern. It also describes how to use the device.


Adhesion properties of resilient lining materials bonded to light-cured denture resins. This study compared the adhesive strength of three resilient denture lining materials with different chemical compositions when bonded to visible light-cured (VLC) denture base resin. Shear adhesive strength was evaluated using a simple overlap-joint model. Three different bonding agents were used and the effect of water on the bonding strength was evaluated by a series of samples tested after storage for 4 months. The findings showed that all of the lining materials were acceptable for clinical use but that water storage reduced their bond strength to VLC resin.


Special matrix for use with glass ionomer in restoring molars with Class V root surface lesions. A simple method of making a custom matrix for molar root lesions has been described. The matrix provides anatomic form to the restoration and reduces the chairside time required to contour and finish the restoration.


An atraumatic denture base design for a tooth-bound mandibular removable partial denture. This technique applies accepted fixed prosthodontic pontic design to the denture base design of a tooth-bound removable partial denture. Patient feedback emphasizes the comfort and lack of bulk of the prosthesis compared with a removable partial denture of conventional design placed simultaneously.


Use of nitroglycerin ointment to prevent hypertensive response during electroconvulsive therapy--a study of 50 cases. Fifty patients of either sex, aged between 20 and 60 years undergoing electroconvulsive therapy were included in our study. Each patient was used as his/her own control. We observed the cardiovascular changes without nitroglycerin ointment in the first sitting and in the next sitting with the application of 2 inches of 2% nitroglycerin ointment 45 min before the electroconvulsive therapy. Arterial blood pressure and heart rate increase during electroconvulsive therapy can be effectively attenuated by application of 2 inches of 2% nitroglycerin ointment 45 min before the electroconvulsive therapy (p < 0.001 and p < 0.01 resp.). This may be especially beneficial for patients who are at increased risk of myocardial ischemia and stroke.


Evaluation of two methods employed for cervical ripening. The study evaluates breast stimulation and oxytocin infusion as methods for cervical ripening in patients where an obstetric indication for induction of labour exists. Forty patients with a Bishop score of 5 or 6 were randomly selected for either breast stimulation or oxytocin infusion. In a similar group of 20 cases, no method was employed. The Bishop score improved in 41.2% of cases where breast stimulation was used as compared to 75% where an oxytocin infusion was given. Three foetal deaths in the breast stimulation group brought the study to a stop after 17 cases. Cervical ripening with an oxytocin infusion drip appears to be a better method since infusion dosage can be precisely controlled making the technique more predictable and reliable. Though breast stimulation is effective in ripening the cervix, it may be used only in cases of intrauterine foetal death as it may otherwise adversely affect foetal outcome.


Analysis of 105 uninodular goitres.

Analysis of 105 uninodular goitres. Data on 105 solitary thyroid nodules, confirmed at surgery to be solitary, is presented. Six (5.7%) were malignant, 4 papillary and 2 follicular. The sensitivity and the specificity of 131I radionuclide thyroid scan (n = 90) were 100% and 24% respectively. Similarly, the sensitivity and specificity of fine needle aspiration cytology (n = 65) was 75% and 100% respectively. In both instances, the "gold standard" was the histopathology of the surgically removed nodule. In order to avoid unnecessary surgery, without missing malignancy, we would recommend the combination of radionuclide thyroid scan and FNAC for investigation of solitary thyroid nodules.


Significance of negative hysteroscopic view in abnormal uterine bleeding. Ninety six cases of abnormal uterine bleeding were evaluated by both panoramic hysteroscopy and dilatation and curettage. The indications for hysteroscopy included postmenopausal bleeding, infertility with abnormal bleeding, abnormal bleeding and suspected leiomyoma with bleeding. Twenty three patients had abnormal hysteroscopy findings. Hysteroscopy diagnosed endometrial polyp and submucus leiomyoma with 100% accuracy. In 17 cases, the results of hysteroscopy and curettage were in agreement and hysteroscopy revealed more information than curettage in 6 cases. Among the remaining 73 cases with 'negative' hysteroscopic view, an abnormality was detected by tissue sampling in only 2 patients. The specificity and positive predictive value of hysteroscopy is 100%. The sensitivity of hysteroscopy was greater (92%) than that of curettage (76%) and the negative predictive value of hysteroscopy was 2.8%. Thus, panoramic hysteroscopy may prove to be superior to curettage in making an accurate diagnosis of intrauterine pathology.


Temporary intravascular shunts for peripheral vascular trauma. Polyvinylchloride (PVC) disposable endotracheal suction catheters were successfully used as temporary intravascular shunts in 5 patients of popliteal artery trauma. These simple shunts should be used routinely in such conditions to immediately re-establish blood supply to the ischaemic limb particularly in patients of polytrauma where systemic anticoagulation is contraindicated. This avoids the inherent delay prior to vascular repair and reduces the incidence of irreversible ischemia.


Hyperferritinemia in pregnancy induced hypertension and eclampsia. A study of serum iron and ferritin levels in Indian women with pregnancy induced hypertension (PIH) (mild/severe) and eclampsia compared with controls of similar gestational ages, revealed that mean serum iron was elevated slightly in PIH and significantly in eclampsia as compared to controls. Mean ferritin levels were significantly elevated both in PIH and eclampsia as compared to controls indicating that ferritin measurement in PIH and eclampsia would not reflect iron nutritional status. Lack of significant changes in liver enzymes and in hemoconcentration in PIH and eclampsia indicate that liver damage and altered hemodynamics only play a partial role in causing hyperferritinemia. Possible role of placental ferritin, being released as a result of placental damage in these conditions seems to be an area needing further research.


A comparison of three media for isolation of Nocardia species from clinical specimens. The study was carried out to compare the efficacy of three media namely Modified Thayer Martin medium, McClung's carbon free broth with paraffin bait and paraffin agar in isolating Nocardia species from clinical specimens. Two hundred and seventy six clinical specimens from 245 cases were studied which included cases of bronchopulmonary and systemic infections and cases of mycetoma. Paraffin agar was found to be an inexpensive and selective medium for isolation of Nocardia species when compared with Modified Thayer Martin medium and paraffin bait techniques.


Detection of serum antitrichomonal antibodies in urogenital trichomoniasis by immunofluorescence. Trichomonas vaginalis is a frequently encountered genital pathogen in both males and females. In females, vaginitis due to this parasite is one of the most common manifestation. The indirect fluorescent technique (IFA) test was carried out to detect antitrichomonal antibodies in 370 female patients using whole cell antigen. Seventy one (19.18%) gave positive reaction for either of the class IgG, IgM and IgA antibodies. The level of the IgG class antibodies was found to be higher i.e. 58 (81.69%) than IgM 11 (15.27%) antibodies, which may be suggestive of past infection or a prolonged manifestation by the organisms.


Benign neonatal pneumoperitoneum--an enigma. A case of neonatal pneumoperitoneum in absence of a bowel perforation or intrathoracic pathology has been reported. The cause of such a rare manifestation remains to be established.


Radionuclide assessment of peritoneovenous shunt patency. Denver shunt patency can be easily assessed by sequential scintigraphy with a Gamma camera after an intraperitoneal injection of 99mTc sulphur colloid. If the shunt is patent, the tracer will be seen throughout the shunt upto it's opening into the right atrium. The following case report illustrates the application and usefulness of this procedure.


Adenocarcinoma of the colon in a child.

Adenocarcinoma of the colon in a child. A rare case of a 10 year old boy presenting with history of lower GI bleeding for one year and acute intestinal obstruction was diagnosed as adenocarcinoma of the colon on exploration. One year follow-up after radical colectomy did not show any recurrence.


Paranoid and nonparanoid schizophrenic processing of facially displayed affect. It was proposed that differences between paranoid and nonparanoid schizophrenics in the processing of affective information may reflect underlying differences in their schema for emotion-laden information. Performances of 14 paranoid schizophrenics, 13 nonparanoid schizophrenics, and 15 matched controls were compared on a facial affect judgment task, and a matched control task comprising geometric figures largely devoid of emotional information. Subjects were required to rate friendliness, select an emotion label, and subsequently to remember the stimuli. Nonparanoids were deficient in overall labeling of facial affect, suggesting a weak cognitive schema for emotional information. The paranoids were particularly more accurate than the nonparanoids at labeling the negative facial affects, suggesting well-developed negative emotional aspects in their cognitive schema. Unexpectedly, nonparanoids relative to paranoids displayed a greater memory deficit in the recognition of geometric figures than in the recognition of faces. The nonparanoid deficit suggests these subjects may have poorly organized schema for remembering less structured nonverbal information. The findings support the idea of fundamental cognitive processing differences between paranoid and nonparanoid schizophrenia.


Anaesthetic management in removal of a huge ovarian cyst. A patient with a huge ovarian cyst weighing 38 kg was operated successfully with utmost care to avoid all possible intra and postoperative complications. The same has been presented and the salient features of management have been discussed.


Solitary retroperitoneal angiofollicular lymph node hyperplasia. The fine needle aspiration cytology (FNAC) and ultrasound radiologic features of a solitary retroperitoneal angiofollicular lymph node hyperplasia (AFLNH), hyaline vascular type are described. Based on a combination of the two, this diagnosis can be suggested in the differential diagnosis of a retroperitoneal mass.


A clinical and biological validation of the DSM-III melancholia diagnosis in men: results of pattern recognition methods. Pattern recognition methods were carried out on a sample of 80 depressed men, assessed by means of 14 items relevant to depressive symptomatology of the Structured Clinical Interview for DSM-III-R. 1985 edition (SCID). A cluster analysis generated two classes, which were described as a vital (n = 35) and a nonvital cluster (n = 45). Vital depressives were characterized by psychomotor disorders, loss of energy, cognitive disturbances, a distinct quality of mood, early morning awakening and nonreactivity (the "vital" symptoms). Our findings support the descriptive validity of the DSM-III melancholia diagnostic category, although the DSM-III criteria are too conservative and include nonrelevant symptoms (e.g., diurnal variation, anorexia-weight loss) whilst excluding some important items (e.g., loss of energy, cognitive disorders). Vital depressed men were significantly older, more severely depressed and they exhibited biological disturbances (abnormal dexamethasone suppression test, lower basal thyroid secreting hormone) as opposed to nonvital depressives. There are several arguments to support the possibility that both clusters constitute relevant stages in the overall severity of illness continuum, whilst showing qualitative differences with regard to the vital symptoms. In other words, both clusters are continuous categories within the overall severity of illness continuum and form discrete categories with regard to the vital symptoms. By merging the dimensional and categorical hypotheses, we were able to construct a new integrated threshold model: unipolar depression in men is probably a homogeneous disease with reference to overall severity of illness, but--as severity increases--vital symptoms emerge, grouping together into a distinct profile, i.e., vital depression.


Posterior midline cervical fetal cystic hygroma. Posterior midline cervical cystic hygromas (PMC) are frequently found associated with chromosomal aberrations and usually do not survive. The present report illustrates diagnosis of this condition by sonography in an 18 weeks old fetus and an amniocentesis revealed 45 x0 karyotype and increased concentration of alpha-fetoproteins. Pregnancy was terminated in view of Turner's syndrome. The etiology and natural history of the condition is reviewed.


The relationship of personality to mood and anxiety states: a dimensional approach. This study evaluates the relationship of personality to mood and anxiety states in a sample of 50 psychiatric out patients. In order to overcome arbitrariness inherent in categorical diagnoses of affective, personality and anxiety disorders, we use a dimensional approach to personality, mood and anxiety. According to our results, mood and anxiety states affect personality domains differentially. Namely, relatively large portions of personality and behavior, such as higher-order traits of novelty seeking and reward dependence, seem independent from mood and anxiety states. In contrast, the higher-order dimension of harm avoidance and its corresponding lower-order traits reflect changes in mood and anxiety to a much greater extent. Both the likelihood that large portions of personality may be independent from current mood and the likelihood that some precisely delineated personality domains tend to change simultaneously with current mood may improve our understanding of the relationship of personality to emotionality and affective disorders.


Distribution of peripheral lymphocytes in Alzheimer patients and controls. Deficient immunoregulation has been postulated to play a role in the pathogenesis of Alzheimer's dementia. Recently, lymphopenia was reported to be more prevalent in Alzheimer patients than in control subjects. In addition, a decreasing number of total lymphocytes was found to be significantly correlated with increasing severity of dementia. In an attempt to replicate these findings, we studied 55 Alzheimer patients and 41 healthy controls of comparable age and gender, but found no significant difference in the distribution of total lymphocytes between these groups. Furthermore, total lymphocytes were not significantly correlated with dementia severity. Our findings, therefore, do not lend further support to an immune hypothesis for Alzheimer's dementia.


Perception of breath components by the tropical bont tick, Amblyomma variegatum Fabricius (Ixodidae). II. Sulfide-receptors. Wall-pore sensilla in the capsule of Haller's organ on foreleg tarsi of the tick, Amblyomma variegatum, show multicellular responses upon stimulation with human and bovine breath. Filtering breath through charcoal removes the stimulant for some of these receptors. Analysis by gas chromatography coupled with olfactory sensillum electrophysiological recordings indicates that an ethanol extract of the breath components trapped on charcoal contains a major stimulant eluting at the same retention time as H2S. Two types of H2S-sensitive receptors have been identified. They are housed in separate sensilla, and are called sulfide-receptor 1 and 2. Although, both receptor types are characterized by a high sensitivity to H2S with an estimated threshold of ca. 0.1 ppb and a response range covering 5-6 log orders of magnitude, their overall response to sulfides and mercaptans is nevertheless dissimilar. The type 1 receptor fires slightly more upon stimulations with H2S than type 2, whereas ethylmercaptan induces a stronger response from type 2, and dimethyl sulfide activates only receptor 2. In a bioassay, H2S tested at concentrations of ca. 0.02 ppm and 1 ppm equally arouses 60% of resting ticks. Two-thirds of these ticks quest the air with their first pair of legs, and the remainder start active search. By contrast, H2S at ca. 1 ppm in a mixture with CO2 severely diminishes the locomotor stimulating effect of CO2.


Focusing and accommodation in the brown kiwi (Apteryx australis). Brown kiwis are an endangered species of nocturnal, flightless birds which are native to New Zealand. The resting focus of two specimens has previously been studied by retinoscopy in a zoo while the birds were restrained by their keeper (Sivak and Howland 1987). Those birds appeared to be hyperopic (farsighted) by 2-7 D. In this study, examination with infrared photorefraction of the focusing of two unrestrained, feeding birds showed that they could focus objects at infinity and objects in their immediate environment and that they had modest powers of accommodation. Measurements on two 6 month old kiwi chicks showed their corneal radius of curvature to be between 2.90 and 3.00 mm (117 D and 101 D in power).


Temporal analysis of adaptation in moth (Trichoplusia ni) pheromone receptor neurons. The temporal pattern of response in chemoreceptor neurons reflects both the temporal distribution of stimuli and the timing of signal transduction, action potential generation and propagation. Here we analyze the temporal characteristics of the responses elicited in pheromone receptor neurons by computer-controlled rectangular pulses of odorant. Extracellular recordings from the HS sensilla trichodea on the antenna of male Trichoplusia ni reveal the activity of two neurons: the "A" neuron, which responds to the major component of the female pheromone blend, (Z)7-dodecenyl acetate and the "B" neuron, which responds to (Z)7-dodecenol. "B" neurons were divided into two classes (HR, LR), based on the magnitude and temporal pattern of their response to (Z)7-dodecenol. Most "A" and HR "B" neurons responded to rectangular pulses of various durations (0.1-40 s) with an initial phasic burst (approximately 100 ms), followed by a slowly declining tonic component. At moderate and elevated pheromone doses, prolonged stimulation resulted in significant reductions in the tonic response levels (adaptation); stimuli of increasing duration effected greater adaptation. Most LR "B" neurons lacked a phasic response component and showed virtually no adaptation with prolonged stimulation. Pheromone receptor neurons may differ in both their spectral and temporal response properties which may provide the animal with additional sensory information for blend discrimination and spatial orientation in complex natural pheromone plumes. The potential functional value of adaptation in the moth pheromone communication system is discussed.


Changes in brain amine levels associated with the morphological and behavioural development of the worker honeybee. Changes in biogenic amine levels associated with the morphological and behavioural development of the worker honeybee are examined. A significant increase in amine levels in the head of the honeybee is associated with transition from the larval to pupal stage. Adult emergence is also accompanied by a significant increase in 5-HT levels in the brain, but no significant change in brain dopamine (DA) levels. NADA (N-acetyldopamine) levels increase during larval and pupal development, but in contrast to both DA and 5-HT, drop significantly during the transition from pupa to adult. Levels of DA in the brain of nectar and pollen forager bees, presumed to be among the oldest adults sampled, were found to be significantly higher than in nurses, undertakers or food storers. These results suggest that an age-dependent change in amine levels occurs in the brain of the worker bee. In the optic lobes, levels of DA and 5-HT were found to be significantly higher in pollen forager bees than in all other behavioural groups. Significant differences in amine levels in the optic lobes of nectar foragers and pollen foragers indicate that some differences in amine levels occur independent of worker age. The functional significance of differences in brain amine levels and whether or not biogenic amines play a direct role in the control of honeybee behaviour has yet to be established.


Synaptic interactions among neurons that coordinate swimmeret and abdominal movements in the crayfish. 1. Many interneurons in the crayfish (Procambarus clarkii) abdominal nervous system influence two behaviors, abdominal positioning and swimmeret movements. Such neurons are referred to as dual output cells. Other neurons which influence either one behavior or the other are single output cells. 2. Extensive synaptic interactions were observed between both dual and single output neurons involved in the control of abdominal positioning and swimmeret movements. Over 60% of all neuron pairs examined displayed interactions. Pairs of agonist neurons displayed excitatory interactions, while pairs of antagonists had inhibitory interactions. This pattern of interaction was observed in about 75% of interactive neuron pairs whether abdominal positioning or swimmeret outputs were considered. 3. Evidence for both serial and parallel connectivity, as well as, reciprocal or looping connections was observed. Looping connections can be found both between the abdominal positioning and swimmeret systems and within each system. 4. Most (28/34) single output neurons were not presynaptic to dual output neurons. No single output neurons were found to excite dual output neurons to spiking, although inhibitory interactions and weak excitations were observed. 5. Abdominal positioning inhibitors displayed properties consistent with a role in mediating some of the coordination between the swimmeret and abdominal positioning systems. 6. None of the dual output neurons examined influenced the swimmeret motoneurons directly.


Characteristics of dynamic postural reactions in the locust hindleg. The use of the locust (Schistocerca americana) hindleg in postural control was examined in animals that stood on a repeatedly swayed vertical substrate. Myograms were recorded from leg muscles and the angle of the femoro-tibial joint was monitored photographically. Two discrete strategies were observed; in compensatory reactions the hindleg was held in place, while in "flexion" reactions, the leg was moved, most often to complete flexion of the femoro-tibial joint. Tightly coupled, rhythmic bursting occurred in the flexor and levator muscles of the leg during compensatory reactions. Bursting was initiated repeatedly when the substrate was being pulled away from the animal. Bursting was correlated with subsequent decreases in the rate of change of the femoro-tibial joint angle. Compensatory and "flexion" reactions occurred preferentially in different ranges of joint angles: most often, compensatory reactions occurred in the mid-range, while "flexion" reactions were elicited in the extremes of joint angle. These differences may be due to the mechanical advantages of the tibial muscles and the leg may be moved to full flexion because of a locking mechanism of the flexor muscle tendon. These reactions are compared with known reflexes of hindleg proprioceptors and contrasted with similar responses of vertebrates.


Motion analysis of leg joints associated with escape turns of the cockroach, Periplaneta americana. Considerable information is now available on the neural organization of the escape system of the American cockroach. To relate these data to the behavior, we need detailed information on the movements made at the principle leg joints that produce the turn. We used motion analysis of high speed video records to acquire such information. Records from both free ranging and tethered animals were analyzed. 1. We analyzed individual joint movements using a tethered preparation. Stimuli from 4 different angles around the animal were used. For all wind angles, the femur-tibia (FT) joint on the mesothoracic leg that is ipsilateral to the wind source extended while the contralateral mesothoracic FT joint flexed. This moved both of these legs laterally toward the wind source. In freely moving animals the FT movements provide forces that turn the animal away from the wind source. 2. The ipsilateral mesothoracic coxa-femur (CF) joint extended for all wind angles. The contralateral mesothoracic CF joint extended in response to most winds from the rear, but switched to flexion in response to wind from the side and front. As a result of these joint movements, rear wind resulted in rearward movements of the contralateral mesothoracic leg, while side and front wind resulted in more forward movements of that leg. 3. The CF and FT joints for both ipsilateral and contralateral metathoracic legs extended to wind from the rear and switched to flexion as the wind was placed at more anterior positions around the animal. In freely moving animals, extension of these joints would push the animal forward. Flexion would pull the animal backward. 4. Several of the joints showed correlations between rate of movement and initial joint angle. That is, joints that were already flexed at the onset of stimulation tended to move at a faster rate to a final position than joints that started at a more extended position. 5. Metathoracic FT and CF joints showed a high degree of positive correlation during the escape movements. Indeed, many curves showing movement of metathoracic FT and CF joints with time were virtually identical.


Intersegmental interneurons serving larval and pupal mechanosensory reflexes in the moth Manduca sexta. 1. Intersegmental interneurons (INs) that participate in the larval bending reflex and the pupal gin trap closure reflex were identified in the isolated ventral nerve cord of Manduca sexta. INs 305, 504, and 703 show qualitatively different responses in the pupa than in the larva to electrical stimulation of sensory neurons that are retained during the larval-pupal transition to serve both reflexes. Action potentials produced by current injected into the 3 interneurons excite motor neurons that are directly involved in the larval and pupal reflexes. The excitation of the motor neurons is not associated with EPSPs at a fixed latency following action potentials in the interneurons, and thus there do not seem to be direct synaptic connections between the interneurons and the motor neurons. 2. IN 305 (Fig. 2) has a lateral soma, processes in most of the dorsal neuropil ipsilateral to the soma, and a crossing neurite that gives rise to a single contralateral descending axon. IN 305 is excited by stimulation of the sensory nerve ipsilateral to its soma in the larva and the pupa. Stimulation of the sensory nerve contralateral to its soma produces an inhibitory response in the larva, but a mixed excitatory/inhibitory response to the identical stimulus in the pupa. 3. IN 504 (Fig. 3) has a lateral soma, processes throughout most of the neuropil ipsilateral to the soma, and a crossing neurite that bifurcates to give rise to a process extending to the caudal limit of the neuropil and an ascending axon. IN 504 is excited by stimulation of the sensory nerve ipsilateral to its soma in both larvae and pupae, while the response to stimulation of the sensory nerve contralateral to its soma is inhibitory in the larva but mixed (excitatory/inhibitory) in the pupa. 4. IN 703 has a large antero-lateral soma, a neurite that extends across to the contralateral side giving rise to processes located primarily dorsally in both ipsilateral and contralateral neuropils, and two axons that ascend and descend in the connectives contralateral to the soma (Fig. 4). IN 703 responds to stimulation of the sensory nerves on either side of the ganglion, but the form of the response changes during the larval-pupal transition. In the larva, the response consists of very phasic (0-2 spikes) excitation, but in the pupa there is a prolonged excitation that greatly outlasts the stimulus (Fig. 6).(ABSTRACT TRUNCATED AT 400 WORDS)


Xenopus exhibits seasonal variation in retinotectal latency but not tecto-isthmo-tectal latency. 1. The tectum of Xenopus receives visuotopic input from both eyes. The contralateral eye's projection reaches the tectum directly, via the optic nerve. The ipsilateral eye's projection reaches the tectum indirectly, via the nucleus isthmi and isthmo-tectal projection. 2. Because of the multi-synaptic nature of the ipsilateral pathway, there is an inherent delay between the time that information from the contralateral eye reaches the tectum and the time that information from the ipsilateral eye arrives at the tectum. The length of the intertectal delay is a function of the latencies of the contralateral and ipsilateral pathways. 3. The length of this intertectal delay has functional, as well as developmental, implications with regard to the role of N-methyl-D-aspartate receptors in tectal cell activity and development of orderly synaptic connections. 4. We have found that the latencies of the contralateral and ipsilateral pathways exhibit a seasonal variation, increasing during the winter months. The increases of both latencies during the winter were of similar magnitude, indicating that there were no significant changes in intertectal delay. The seasonal alteration in contralateral latency was not affected by dark-rearing and was affected to only a minor extent by a week-long alteration of ambient temperature.


Interneurons of the subesophageal ganglion of Sarcophaga bullata responding to gustatory and mechanosensory stimuli. Intracellular recordings were made from interneurons in the subesophageal ganglion (SEG) of Sarcophaga bullata while stimulating the labellar lobes with solutions of sucrose, NaCl and with distilled water. Neurons that responded to sucrose did not respond to NaCl and vice versa, while sucrose-sensitive neurons often responded weakly to water. Several of the recorded neurons were filled with Lucifer Yellow, and their morphology was reconstructed. Most showed extensive arborizations within the SEG, suggesting that they were local interneurons involved in the early stages of gustatory processing. Some of the filled neurons had extensive projections to the brain, in addition to arborizations in the SEG. This is the first published record of gustatory interneurons in the higher flies.


Midbrain auditory sensitivity in the spring peeper (Pseudacris crucifer): correlations with behavioral studies. 1. We derived audiograms from recordings of multiunit activity in the torus semicircularis of 10 males and 6 females of the spring peeper from central Missouri, USA. We used free-field stimulation with tone bursts that had temporal properties similar to typical advertisement calls and that ranged in frequency from 500-6000 Hz. 2. Audiograms from different electrode positions in the same animal had the same general shape. There was no evidence of tonotopy. 3. Audiograms showed two regions of maximal sensitivity: a low-frequency region (500-700 Hz); and a high-frequency region (2000-4000 Hz). Absolute thresholds and frequencies of maximum sensitivity varied considerably from individual to individual. 4. Audiograms derived from all individuals of each sex indicated that in the high-frequency region, corresponding to the frequency range of advertisement calls, males were more broadly tuned than females. However, tuning in both sexes was relatively weak, and the data predict relatively little selectivity in behavioral responses over the entire range of variation in frequency of the advertisement call in local populations. 5. The results are discussed in terms of behavioral experiments with both males and females from the same populations in central Missouri. We show that merely summarizing the audiograms based on estimates of minimum thresholds of a population or species may mask significant individual differences in tuning. Moreover, most behavioral studies are conducted at playback levels considerably above threshold. For these reasons, behavioral selectivity is not always accurately predicted by inspection of "average" audiograms.


Does reactivity testing in the laboratory reflect blood pressure changes elsewhere? This study examines whether reactivity testing in a laboratory setting might identify individuals whose blood pressure (BP) fluctuates excessively outside of the laboratory. Eighty-eight normotensive and untreated hypertensive patients were studied. Patients' BPs were obtained repeatedly on two separate screening occasions. They were subsequently admitted to a research ward, and 4 days later their BPs were measured at resting baseline and in response to a series of stressful tasks. Blood pressure declined by 14/11 mm Hg +/- 1.2/1.1 mm Hg (SE) from screening to the in-patient resting baseline. The four stressful tasks all led to increases in BP over the in-patient resting baseline level. Individuals with increased amounts of task-induced reactivity in the laboratory were also more likely to be those whose BP declined the most from out-patient screening to hospitalized baseline. The average correlation between the drop in BP associated with hospitalization and the BP reactivity to each stressor task was r = 0.33 for systolic BP (p < 0.01) and r = 0.24 for diastolic BP (p < 0.05). Reactivity responses in a laboratory setting may convey information about blood pressure fluctuation in the real world.