Enhancement of muscle regeneration in the rat gastrocnemius muscle by low energy laser irradiation. The effect of low-energy laser (He-Ne) irradiation on the rate of skeletal muscle regeneration after partial excision of the rat gastrocnemius muscle was studied using quantitative histological morphometric methods. The injured zones of the experimental rats were subjected to direct He-Ne laser (632.8 nm wavelength) irradiation (6.0 mW for 2.3 min) immediately following injury and once daily thereafter for 5 days. Muscles that were injured as above and subjected to red or room light irradiation served as a control group. The volume fraction (percent of total volume of injured zone) of the mononucleated cells in the injured zone decreased gradually with time after injury, but more rapidly in the laser irradiated muscles than in the control. At 3 days post-injury the myotubes in the laser-irradiated muscles populated a significantly higher percentage (13.9 +/- 1.1%) of the injured area than in the control muscles (7.8 +/- 1.0%). The volume fraction of the young myofibers in the laser irradiated muscles exceeded 30.6 +/- 2.2% and 49.6 +/- 5.6% at 8 and 11 days post-injury, respectively, while in control muscles these structures comprised only 9.6 +/- 1.0% and 27.2 +/- 3.8% of the injured zone at 8 and 11 days after injury, respectively. It is concluded that He-Ne laser irradiation during the regeneration process promotes muscle maturation in the injured zone following partial excision of the rat gastrocnemius muscle.


Postnatal development of zinc-containing cells and neuropil in the visual cortex of the mouse. The postnatal development of zinc-containing synaptic boutons and their cells of origin in the visual cortex of a pigmented mouse is described. Two phases can be distinguished. During the early phase zinc-containing neuropil is first apparent by postnatal day 3. By day 7 a light, but distinct neuropil staining sketches the primary and secondary visual cortices. The primary visual area contains light precipitate in layers V and VI as well as the monocular portion of layer II/III. The secondary visual areas contain slightly denser precipitate in layers II/III through VI. The transition to the second phase is marked by a large increase in precipitate density by day 11. Thereafter, the intensity of the neuropil staining increases to day 28, first in layer II/III and then in layer V, as the adult pattern of neuropil staining gradually develops. In the primary visual cortex precipitate is dense in layers II/III and V, moderate in layer VI, and sparse in layers I and IV. In the secondary visual areas the precipitate is dense in layers II/III and V and moderate in the lower portion of layer I and in layers IV and VI. Cells of origin of zinc-containing boutons are visible by the end of the second postnatal week in layer II/III of the secondary visual cortex. By 21 days of age the pattern of staining in the mature mouse is established, and cells in layers II/III and VI are labeled in both the primary and secondary visual cortices. The developmental sequence of zinc-containing cells and neuropil does not preclude an involvement of zinc in the postnatal regulation of NMDA receptor function.


Local signalling in dermomyotomal cell type specification. The development and differentiation of the avian myotome was studied after removal of the neural tube, including neural crest, and after replacement of dorsal half-somites by ventral half-somites. Results show that in the absence of neural tissue myoblast differentiation within the somites does not take place. Ventral half-somites are able to undergo muscle differentiation if they were grafted in place of dorsal half somites. It is suggested that local signals must be responsible for the dorsalisation of the newly formed somite including myoblast differentiation. Neural crest cells are discussed as possible sources of these signals.


Expression of alpha-tropomyosin during cardiac development in the chick embryo. A new monoclonal antibody (mAb) that recognizes alpha-tropomyosin in cardiac muscle cells was used in a qualitative (polyacrylamide gel electrophoresis and indirect immunofluorescence) and quantitative (fluorescence-activated cell sorting) study of the expression of this protein during heart development. alpha-Tropomyosin expression was weak in early stages of chick embryo development (Hamburger and Hamilton stage 18), and increased steadily until Hamburger Hamilton stage 40. In early stages, the protein was found mainly in cytoplasm, whereas by the final stages, it was more abundant in the cytoskeletal compartment. The mAb cross-reacted with alpha-tropomyosin in smooth and striated muscle cells from chickens, mice, and humans, but did not cross-react with nonmuscle tropomyosin.


Effects of prostaglandin inhibition on the bone activities associated with the spontaneous drift of molar teeth in the rat. Little is known about local bone regulation that enables spontaneous molar tooth drift. In this study the role of prostaglandins (PGs) were investigated in the rat by inhibiting PG-synthesis with indomethacin (7 mg/kg/d). Untreated animals were killed at the start of the experiment, while treated ones were killed after 3, 7, or 14 days of treatment. Mandibles were processed for histomorphometry without demineralization. Changes in osteoclasts and extent of the different steps of the bone remodeling sequence (resorption, reversal, and formation) were assessed along the remodeling side of the socket of the buccal root of the first molar. The total number of osteoclasts decreased after 7 days of PG inhibition (P < 0.01 vs controls) and then partially recovered. This change was due to a sharp decrease in active cells on day 7 (P < 0.01), while inactive cells remained unchanged throughout the experimental period. The extent of resorption fell on day 7 (P < 0.01) and then recovered almost to the control level on day 14. Reversal at first increased insignificantly and thereafter decreased (P < 0.02) for the remaining 7 days. Formation was modified only on day 14; at that time it had doubled compared with controls. These results show that PGs are involved in the local regulation of bone remodeling accompanying tooth drift. Resorption inhibition was partial, indicating that other factors participate with PGs in this regulation; in addition, the trend to recovery observed at the end of the experimental period suggests that these factors can take over from PGs to achieve the necessary remodeling of the socket.


Adaptation of cancellous bone to aging and immobilization in growing rats. Two-and-half-month-old female rats were subjected to right hindlimb immobilization or served as controls for 0, 1, 2, 8, 14, and 20 weeks. The right hindlimb was immobilized by bandaging it against the abdomen, thus unloading it. Cancellous bone histomorphometry was performed on microradiographs and double-fluorescent labeled 20 microns sections of the distal femoral metaphyses. Primary spongiosa bone loss occurred rapidly by 2 weeks, and secondary spongiosa bone loss occurred rapidly by 8 weeks of immobilization, and then equilibrated at 60% less bone mass than age-related controls. The negative bone balance induced by immobilization was caused by transient increase in bone resorption, decrease in bone formation, and longitudinal bone growth. The dynamic data of secondary spongiosa cancellous bone showed that percent eroded perimeter was transiently elevated by 55 to 82% between 1 and 8 weeks, percent labeled perimeter was transiently depressed by 32% to 50% between 1 and 14 weeks, mineral apposition rate was depressed by 23% and 19% at 1 and 2 weeks, and bone formation rate-bone area referent was transiently depressed by 35% and 59% at 1 and 2 weeks. All the above parameters were at age-related control levels by 20 weeks of immobilization. However, bone formation rate-tissue area referent was depressed (-65%) throughout the study. Immobilization depressed completely longitudinal bone growth by 2 weeks and remained so. Only 0.65 mm of new metaphysis was generated in the immobilized versus 2.1 mm in controls during the study period. The immobilization induced an early cancellous bone loss which equilibrated at a new steady state with less bone and a normal (age-related control) bone turnover rate. When these findings were compared to an earlier study of 9-month-old virgin females subjected to right hindlimb immobilization up to 26 weeks, we found the adaptive responses of the cancellous bone were identical except that they occurred earlier and equilibrated sooner in younger rats.


Elastic fibers in the duct system of the rat submandibular salivary gland. The submandibular salivary gland originates from the floor of the mouth whose mucosa contains elastic fibers. Therefore, such fibers were sought in the duct system of the derivative organ. In adult rats, light microscopy has indeed revealed fine, circumferential, elastic fibers near the basement membrane of the duct epithelium. In the larger extralobular ducts, they were separated from several layers of longitudinal elastic fibers by a capillary-rich zone sparse in elastic fibers except for fine angular ones. More peripherally, larger angular-appearing fibers were frequently present near the submandibular parasympathetic ganglia in the duct wall. As duct diameter decreased, elastic fiber size and number diminished. Intralobularly, the smaller striated ducts, granular and intercalated ducts, and acini generally lacked such fibers. Electron microscopy of the extraglandular portion of the main duct revealed fibrils extending from both fibroblasts and elastic fibers that were close to the epithelium. Microfibrils coursed from them toward the lamina densa. Anchoring filaments joined the lamina densa to the basal plasma membrane of the epithelium. Elastic fibers also appeared to connect to both capillaries and collagen via finer intermediate structures. These associations might permit dynamic interactions of fibroblasts, fibers, smaller fibrillar components, vasa, and the duct epithelium. This interplay could occur during feeding and grooming when tongue protrusion and neck extension stretch the submandibular duct and the gland itself. As a result, the tensile forces engendered could modify cell geometry and the calibers of the larger ducts' lumens and intercellular spaces, thus affecting the flow and composition of salivary secretion.


Morphology of the kidney of the platypus (Ornithorhynchus anatinus: Monotremata). The platypus kidney shows morphological similarities to those of other mammals. Macroscopically, the cortex is easily distinguishable from the fairly wide medulla. Within the medulla, no clear border is observed between the inner and outer zones. Light and transmission electron microscopically, the glomeruli show quite similar architecture to those of other mammals; however, the glomerular lobulation is very clear. The glomerular tufts are rather simple, but capillary lumen varies widely in size, which is one of the unique features of the platypus kidney. The urinary tubule is generally similar to that of human and other mammals in shape and segmentation; however, the staining specificities of histochemical reactions and the shape of epithelial cells of the Henle's loop differ from those of other mammals. The most conspicuous features are: 1) although no protein casts are found in the tubular lumina, epithelial cells of the proximal convoluted tubule (PCT) have numerous electron-dense vesicles as in human nephrotic kidneys; and 2) the platypus Henle's loop consists of the thick epithelial cells similar to the mammalian type nephron of birds. As compared to those of other mammals such as humans and rats, our observations suggest that the platypus kidney is less developed, in terms of evolution.


Cystogenesis of the ovarian antral follicle of the rat: ultrastructural changes and hormonal profile following the administration of dehydroepiandrosterone. Immature 27-day-old female Sprague-Dawley rats were administered daily subcutaneous injections of dehydroepiandrosterone (DHEA, 5 mg/100 g BW) to induce the formation of ovarian follicular cysts. Groups of rats were killed on days 0, 10, 15, 20, 25, and 30. Ovaries from each group of rats were processed for light and electron microscopy and for follicular or cystic fluid hormone analysis. Normal antral follicle fluid, PMSG-treated preovulatory follicular fluid, and cystic fluids were analyzed for progesterone (P), estrone (E1), estradiol (E2), testosterone (T), delta 4-androstenedione (delta 4-A), 5 alpha-dihydrotestosterone (DHT), luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL). DHEA induced anovulation, acyclicity, and the formation of follicular cysts. In certain antral follicles, there was a dramatic increase in the quantities of smooth endoplasmic reticulum (SER) in the granulosa cells and many mitochondria had tubular cristae. Further depletion of granulosa cell number was associated with intense blebbing of the cytoplasm into the follicle antrum. Formation of the ovarian follicular cyst was completed when the entire cyst was lined by a single layer of transformed granulosa cells in contact via adhering, gap, and tight junctions. These cells had little cytoplasm, mitochondria with lamellar cristae, vast basal and apical bands of microfilaments, and an extensive array of smooth-surfaced endocytotic invaginations on the basal plasma membrane. These endocytotic pits may subsequently form smooth-surfaced vesicles and thereby serve as one mechanism for moving fluid from the ovarian interstitium into the cyst. Theca interna cells were rarely observed in the peripheral regions of the cyst. Abundant smooth muscle cells were located beneath the basement membrane of the epithelial cells comprising the cyst wall. These acquired morphological and physiological features may ensure persistence of the ovarian cyst and thus potentiate a chronic pathological condition. In this study it was also shown that progesterone, estrone, and estradiol as well as androgen concentration increased in the follicle after PMSG treatment. With DHEA treatment, the follicular cystic fluid concentrations of these steroids progressively increased to extremely high levels concurrent with the development of the follicular cysts.(ABSTRACT TRUNCATED AT 400 WORDS)


Changes in histochemical distribution of cell surface heparan sulfate proteoglycan in mouse uterus during the estrous cycle and early pregnancy. We have investigated the changes in immunolocalization of a cell surface heparan sulfate proteoglycan (HSPG) in the mouse uterus during the estrous cycle and at the time of implantation in early pregnancy. A monoclonal antibody prepared against syndecan, a cell surface HSPG from mouse mammary epithelium (gift of Dr. M. Bernfield), was reacted with unfixed and fixed frozen sections of uteri from normally cycling, 3.5 and 4.5 days pregnant, and estradiol-treated immature and ovariectomized mature mice. A polyclonal antibody prepared against basal lamina HSPG from Engelbreth-Holm-Swarm (EHS) tumor cells (gift of Dr. John Hassell) was used as a positive control. The latter showed no variation during the estrous cycle or early pregnancy. Localization of syndecan in uterine epithelium changed from basolateral to predominantly basal as the cycle progressed from metestrus toward estrus. A similar pattern was seen in immature and ovariectomized mature females that had received estradiol injections. With the onset of pregnancy, the basolateral localization became progressively less intense from 3.5 days through 4.5 days of pregnancy. Thus, cell surface HSPG distribution is modulated by hormonally dependent changes in cycling and pregnant mice, supporting previous suggestions that early pregnancy in mice is accompanied by a turnover and rearrangement of uterine epithelial cell surface.


Structural analysis of fetal rat lung development. The primary aim of this morphological investigation was to elaborate a concept allowing us to coherently define reference spaces for morphometric analysis of fetal lung development. Beyond this quantitative goal, morphological analysis of cell types, definition of compartments, and reflection about the prospective fate of their constituents provided per se new insights into the developmental processes. Lungs of rat fetuses aged 17-23 days and newborns aged 20 hours were fixed with an osmium tetroxide and glutaraldehyde mixture and their volume determined. Left lungs were embedded in Epon and investigated by light and electron microscopy. The right lung of one animal per group was embedded in methacrylate and step sections obtained to precisely locate the airways within the mesenchyme. The various cell types, their topographical relationships, and their morphological alterations with ongoing development were analyzed with regard to their prospective potentials of differentiation. The developing lung could be partitioned into four zones further subdivided into defined compartments. Zone I forms a superficial mantle around the lobes and the future acini. Consisting of primitive mesenchymal cells, it represents a zone of growth which disappears with the onset of the saccular stage. Zone II is mainly a zone of differentiation. Its interstitium stains intensely due to a dense population of dark cells. Up to gestational day 19, zone II contains future conductive airways with their vessels. After day 21, it comprises the whole prospective gas exchange region. Zones III and IV contain the elements of the airway tree and vascular system, zone IV corresponding to the most proximal generations with an adventitial layer. For all differentiation processes, a centrifugal directionality is manifested.


Ultrastructure and immunocytochemistry of the neuroepithelial bodies in the lung of the tiger salamander, Ambystoma tigrinum (Urodela, Amphibia). Light and electron microscopy of the lungs of Ambystoma tigrinum (Urodela) revealed a relatively complex pattern of the neuroendocrine (NE) cells. In the apical parts of smaller septa single NE cells not associated with nerve fibres were covered and surrounded by pneumocytes. The larger septa possessed small areas of ciliated epithelium, in which the NE cells were grouped in a form of neuroepithelial bodies (NEB) consisting of 3-5 cells and covered by goblet cells. NE cells possessed a large nucleus with patches of condensed chromatin, clear cytoplasm, and membrane-bound vesicles of variable morphology and size, containing an electron dense interior surrounded by a lucent space. The size of these dense core vesicles (DCV) ranged from 70-140 nm, while rarely the larger ones exhibited a diameter of 300-600 nm. In some NEB a second type of NE cells was observed for the first time in an amphibian species: these cells communicated with the air space and exhibited on their surface microvilli and a single modified cilium with a 8 + 1 microtubule arrangement. Their cytoplasm contained two types of DCV: dense core granules with a diameter of 140-260 nm and vesicles 320-700 nm in diameter with a moderately electron dense interior. The NEB were associated with intracorpuscular, sensory nerve terminals morphologically afferent and efferent. By immunocytochemistry, the NE cells revealed the presence of serotonin, met-enkephalin, and leu-enkephalin. A paracrine and chemoreceptor role is proposed for NEB of Ambystoma tigrinum.


Comparative study of sexual dimorphism of the innominate bone in rodents and amphibians. Sexual dimorphism in the shape of the innominate bone was demonstrated in the rat, mouse, Chinese hamster (Cricetulus griseus), frog (Ranna nigromaculata), and newt (Cynops pyrrhogaster) with a computer-assisted morphometric technique. In the rat, mouse, and hamster, ratios of ischium and pubis widths to the innominate bone length (INL) were larger in the males than in the females; however, the ratio of pubis length to INL was larger in the females than in the males. In the frog, the ratio of distance between the upper edge of the acetabulum and the lower edge of the pubis to INL was larger in males than in females. In the newt, ratios of width of ischiopubis and the longitudinal length of the ischiopubis to INL were larger in females than in males.


Lymphoid cells in the harderian gland of the rodent Octodon degus. The Harderian gland of the degu (Octodon degus) is composed of tubulo-alveolar secretory units that share most of morphological features found in the Harderian glands of other rodents. However, a peculiar characteristic observed in the glands of female degus is the existence of lymphoid cell clusters within the connective tissue surrounding the secretory adenomeres. Lymphocytes and lymphoblasts are found associated with blood vessels and especially with nerve bundles in the medullary region of the gland. Occasionally, macrophages and plasma cells are also observed. Although the Golgi apparatus appears well developed, the ultrastructural characteristics of most of these lymphoid elements correspond to those of inactive lymphocytes. Unmyelinated fibers containing clear and dense-core vesicles are found closely related to lymphocytes. On some occasions, lymphocytes present extensive areas of apposition with structures resembling intercellular junctions. The analogy of the lymphoid clusters reported in this study with those described in the avian Harderian gland is discussed.


Distribution of p21ras in postimplantation rat embryos. Expression of ras cellular oncogenes during the early postimplantation period in the rat was investigated using immunohistochemistry to p21ras. A broad spectrum polyclonal antibody recognizing N-, Ha- and Ki- forms of p21ras was used in an indirect avidin-biotin-peroxidase (ABC) technique. Positive staining indicating the presence of p21ras was found in embryos from 6.5 to 12 days embryonic age. In early egg cylinders (6.5 days), positive staining for p21ras was observed on the ectoplacental cone, primitive ectoderm and trophectoderm, while primitive endoderm and parietal endoderm appeared paler. In later egg cylinder stages (7.5 days), strong positive staining was observed in the primitive embryonic ectoderm and ectoplacental cone, but parietal and visceral endoderm still appeared to be devoid of positive staining. As development proceeded during primitive streak stages, the visceral and parietal endoderm became positively stained. By 10 days, all tissues appeared to be positive for p21ras, with strong staining appearing in the heart and neural elements. Therefore, p21ras does not appear to be ubiquitous in the rat conceptus prior to gastrulation, but shows differential distribution, appearing later in endodermal derivatives. Possibly p21ras is involved in determination of the ectodermal and endodermal lineages.


Localization of extracellular matrix components in developing mouse salivary glands by confocal microscopy. The importance of the extracellular matrix (ECM) in epithelial-mesenchymal interactions in developing organisms is well established. Proteoglycans and interstitial collagens are required for the growth, morphogenesis, and differentiation of epithelial organs and the distribution of these molecules has been described. However, much less is known about other ECM macromolecules in developing epithelial organs. We used confocal microscopy to examine the distribution of laminin, heparan sulfate (BM-1) proteoglycan, fibronectin, and collagen types I, IV, and V, in mouse embryonic salivary glands. Organ rudiments were isolated from gestational day 13 mouse embryos and cultured for 24, 48, or 72 hours. Whole mounts were stained by indirect immunofluorescence and then examined using a Zeiss Laser Scan Microscope. We found that each ECM component examined had a distinct distribution and that the distribution of some molecules varied with culture time. Laminin was mainly restricted to the basement membrane. BM-1 proteoglycan was concentrated in the basement membrane and also formed a fine network throughout the mesenchyme. Type IV collagen was mainly located in the basement membrane of the epithelium, but it was also present throughout the mesenchyme. Type V collagen was distributed throughout the mesenchyme at 24 hours, but at 48 hours was principally located in the basement membrane. Type I collagen was distributed throughout the mesenchyme at all culture times, and accumulated in the clefts and particularly at the epithelial-mesenchymal interface as time in culture increased. Fibronectin was observed throughout the mesenchyme at all times.


Hemizona assay and its impact on the identification and treatment of human sperm dysfunctions. The HZA, a functional test for human gamete interaction, has become a useful and valuable experimental tool for physiological and cellular analysis of the early events leading to fertilization. The analysis of the conventional semen parameters with emphasis on sperm morphology (as judged by strict criteria) and motion characteristics (evaluated by computer assisted analysis) constitutes the first obligatory step for a critical evaluation of male-factor patients. Patients in whom fertilization disorders are suspected should be evaluated through bioassays of sperm function of established accuracy. The HZA, a bioassay of sperm-zona binding capacity is here proven to be highly predictive of IVF outcome. Ultimately, our increasing knowledge of sperm biology and dysfunction will provide a basis for a better diagnosis (membrane receptor defects and metabolic/biochemical abnormalities?) as well as better therapeutic interventions in patients with sperm disorders. It seems likely that the HZA may be eventually replaced by a standardized test kit in which recombinant human DNA-derived zona receptors mimic the natural function of the hemizonae currently used. This ZP3 reagent may also be a useful antigen for contraceptive development. The HZA therefore constitutes a useful adjuvant in the armentarium for the diagnosis and therapy of male-factor patients.


Evaluation of bovine cervical mucus penetration as a test of human spermatozoal function for an in vitro fertilization programme. Thirty-two couples participating in an in vitro fertilization (IVF) programme were evaluated as regards the prognostic value on fertilization of spermatozoal performance through flat capillary tubes filled with standardized midcycle bovine cervical mucus (Penetrak, Serono Diagnostics, Surrey, UK). A statistically significant correlation (P < 0.033) was observed between the distance travelled by the neat spermatozoa in the mucus and the % penetration of oocytes at IVF. There were also significant correlations between motility and progression (P < 0.004) and a borderline correlation between progression and the Penetrak results (P < 0.098). There was no significant difference between the Penetrak distances travelled between the 9 who conceived (33.4 mm) and the 23 who did not (29.9 mm). While the test does add to the knowledge of fertilization potential, the results extrapolated to a larger series would give false positive rates of 25% and false negative rates of 11%. The absence of a clear end point renders the Penetrak mucus penetration test insufficiently accurate to be used as a main measure of the male factor when advising for or against IVF therapy.


Comparison of semen analysis between the two Hamilton-Thorn semen analysers. This study was designed to assess the reproducibility of the computer-assisted semen analysis (CASA) system. Semen specimens from 41 suspected subfertile patients were analysed on two identical Hamilton-Thorn Motility analysers (HTM, model 2030, version 7). Specimens were analysed after liquefaction at 37 degrees C for 30 min on two HTMs adjusted to the same gate settings and by using the same semen droplet loaded on a Makler counting chamber prewarmed at 37 degrees C. Significant differences were seen in the total sperm count (P < 0.0004), motile sperm count (P < 0.004), amplitude of lateral head displacement (P < 0.0001), linearity (P < 0.01), and beat cross frequency (P < 0.0001) between the two HTMs. No significant differences between the two machines was seen in the case of other sperm motion parameters: percentage motility, average path velocity, straightline velocity, curvilinear velocity, straightness, and progressive motility. Our results indicate that the reproducibility of several semen parameters analysed by HTM is poor, and steps to remedy this problem are necessary.


Hemodynamic and organ blood flow responses to halothane and sevoflurane anesthesia during spontaneous ventilation. This study compared systemic hemodynamic and organ blood flow responses to equipotent concentrations of halothane and sevoflurane during spontaneous ventilation in the rat. The MAC values for halothane and sevoflurane were determined. Cardiac output and organ blood flows were measured using radiolabeled microspheres. Measurements were obtained in awake rats (control values) and at 1.0 MAC halothane or sevoflurane. The MAC values (mean +/- SEM) for halothane and sevoflurane were 1.10% +/- 0.05% and 2.40% +/- 0.05%, respectively. The PaCO2 increased to a similar extent in both groups compared with control values. During halothane anesthesia, heart rate decreased by 12% (P < 0.01), cardiac index by 26% (P < 0.01), and mean arterial blood pressure by 18% (P < 0.01) compared with control values. Stroke volume index and systemic vascular resistance did not change. During sevoflurane anesthesia, hemodynamic variables remained unchanged compared with control values. Coronary blood flow decreased by 21% (P < 0.01) and renal blood flow by 18% (P < 0.01) at 1.0 MAC halothane, whereas both remained unchanged at 1.0 MAC sevoflurane. Cerebral blood flow increased to a greater extent with halothane (63%; P < 0.01) than with sevoflurane (35%; P < 0.05). During halothane anesthesia, hepatic arterial blood flow increased by 48% (P < 0.01), whereas portal tributary blood flow decreased by 28% (P < 0.01). During sevoflurane anesthesia, hepatic arterial blood flow increased by 70% (P < 0.01) without a concomitant reduction in portal tributary blood flow. Total liver blood flow decreased only with halothane (16%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)


Effect of multiple centrifugations on the evaluation of the acrosome reaction in human spermatozoa. This study was undertaken to assess the effect of multiple centrifugations on the human acrosome reaction and in vitro fertilizing ability. Semen samples were obtained from sperm donors and from patients participating in our in vitro fertilization programme. Measured sperm samples were centrifuged twice (400xg for 5 min) before or after the induction of the acrosome reaction with calcium ionophore A23187 and before the insemination of oocytes. The samples obtained from the sperm donors were used to measure the acrosomal loss by means of indirect immunofluorescence (T6 monoclonal antibody) and the patient samples were used to assess fertilizing ability and cleavage. Samples centrifuged twice before the chemical induction of the acrosome reaction exhibited significantly elevated levels of acrosomal loss (mean = 46%) as compared to the controls (23%). However, the fertilization (P = 0.688) and cleavage (P = 0.187) rates were not significantly different between the controls and the centrifuged samples. The present study has shown that the centrifugation of motility enriched (swim-up) samples may also modify the acrosomal membrane complex, without compromising fertilizing potential.


On the glandular origin of seminal plasma lipids in man. The aim of this study is to examine the glandular origin of seminal fluid lipids in man. The triglycerides, the total cholesterol, the non-esterified fatty acid and the total phospholipids were measured in seminal plasma of vasectomized patients (n = 8) and control subjects (n = 15). The same parameters were measured in seminal plasma collected in three fractions from split ejaculates (n = 10). The total cholesterol and the non-esterified fatty acid are principally prostatic in origin. The phospholipids are secreted by the epididymis but also by the prostate. The origin of the triglycerides seems to be very varied.


Halothane enhances pulmonary artery endothelial eicosanoid release. To determine whether anesthetics alter endothelial eicosanoid release, cultured bovine pulmonary artery endothelial cells were studied during constant flow and pressure perfusion at two oxygen tensions (hypoxia, 50 +/- 2 mm Hg; normoxia, 144 +/- 5 mm Hg; mean +/- SEM) with and without 1% halothane. Endothelialized microcarriers containing approximately 5 x 10(6) cells were loaded into cartridges and perfused (3 mL/min) with Krebs' solution (pH 7.4, at 37 degrees C) equilibrated with each gas mixture. Eicosanoids (6-keto prostaglandin F1 alpha, thromboxane B2, and total peptidoleukotrienes [C4, D4, E4, F4]) were measured by radioimmunoassay and quantified per gram of cellular protein per minute. Eicosanoid release did not vary over time. The 6-keto prostaglandin F1 alpha release increased during hypoxia (normoxia 291 +/- 27 vs hypoxia 395 +/- 35 ng.min-1 x g protein-1; P < 0.01). Halothane (H) increased release of each eicosanoid during both normoxia and hypoxia: 6-keto prostaglandin F1 alpha-normoxia 291 +/- 27 versus normoxia + H 356 +/- 32 ng.min-1 x g protein-1, hypoxia 395 +/- 35 versus hypoxia + H 464 +/- 40 ng.min-1 x g protein-1, P < 0.05; thromboxane B2-normoxia 19 +/- 2 versus normoxia + H26 +/- 2 ng.min-1 x g protein-1, hypoxia 20 +/- 2 versus hypoxia + H 38 +/- 5 ng.min-1 x g protein-1, P < 0.001; leukotriene-normoxia 363 +/- 35 versus normoxia + H 489 +/- 52 ng.min-1 x g protein-1, hypoxia 329 +/- 29 versus hypoxia + H 455 +/- 39 ng.min-1 x g protein-1, P = 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)


Andrological study of an intersex ram.

Andrological study of an intersex ram. An anatomic, histologic, and cytogenetic study was carried out on a young single-born ram of 'Bergamasca' breed. At an anatomical level the subject, with anomalous presence of horns adherent to the head, presented hypoplastic testicles descended in two distinct scrotal sacs, hypospadias and small penioid body. The histopathologic analysis showed atrophy of the testicular parenchyma while at a cytogenetic level, sexual chromosome mosaicism was found with XX and XY cells, both at lymphocytic (73%-54, XX; 27%-54, XY) and fibroblastic level. Therefore this finding cannot be explained simply referring to freemartinism.


Morphometric and ultrastructural studies on the rat testis following administration of antiserum to human seminal plasma inhibin. A study was undertaken to see the effects of antiserum to human seminal plasma inhibin (hSPI) on the morphology of rat testis. Morphometric, light microscopic, and ultrastructural studies were done on rat testis after 4, 8, and 12 weeks of administration of antiserum to hSPI. Daily sperm production rate was also estimated by histometric method. The light microscopic analysis showed a slight decrease in tubular diameter which was not significant. The degenerative changes in the tubules were marked after 12 weeks of treatment. The daily sperm production rate was reduced by 50% after 12 weeks of treatment. The ultrastructural study revealed phagocytosis of elongated spermatids and spermatozoa enclosed in a vacuole surrounded by Sertoli cells. The Sertoli cells were dedifferentiated into an immature type. The spermatogonia were not affected. The treatment with antiserum to hSPI alters testicular morphology at the spermatid and mature spermatozoa level. Since treatment with AshSPI is known to elevate the FSH level it appears that the morphological changes correlate with the endocrine status.


Extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation. Extracorporeal membrane oxygenation is still a relatively new technology that has recently achieved recognition after initial clinical disappointment in the late 1970s. At present, it is considered standard therapy for the full-term infant with PPHN who fails CMV and extraordinary, heroic therapy for older children and adults with ARF or cardiac failure, or both. Currently, the emphasis is on developing new technologies for increasing safety and effectiveness. Areas of interest include heparinless circuits, carotid artery reconstruction, improved monitoring, and expanding applications of VV ECMO. As ECMO becomes safer and more effective, it is believed that new and expanding patient populations will emerge to include premature infants, earlier intervention in term infants, and more liberal application to pediatric and adult populations.


Local anesthetic-sensitive electrodes: preparation of coated-wire electrodes and their basic properties in vitro. Coated-wire electrodes with local anesthetic (LA) cation-selective membranes were prepared, and their properties in vitro were investigated. Copper wires (0.8-mm diameter) were coated with gel membranes of 110 mg of poly(vinyl chloride), 5 mg of ion pairs of tetraphenylborate anion with LA cation, 100 mg of dioctylphtalate, and 1.5 mL of tetrahydrofuran. This was the composition determined to be most suitable. Their electromotive force relative to an Ag/AgCl electrode was measured in LA solutions. The lidocaine, dibucaine, and mepivacaine electrodes all showed good Nernstian response at 25 degrees C in aqueous solutions in the concentration ranges of 1 x 10(-4) to 1 x 10(-2) mol/L, 4 x 10(-5) to 1 x 10(-2) mol/L, and 5 x 10(-5) to 1 x 10(-2) mol/L, respectively. The response time was within 10 s. The electrode potential decreased as the pH in the solution increased, with a corresponding decrease of the protonated form of LA. The hydrophobic nature of the LA was closely related to the electromotive force and to the selectivity of the electrode toward various LA cations. Dibucaine, the most hydrophobic, had the highest electrode potential. The more hydrophobic the LA of the electrode, the less it is interfered with by other LA molecules. The more hydrophobic the interferent cation, the more it acts on the electrode potential. The electrode system could also measure LA in human plasma at 37 degrees C, although the responsiveness was depressed in the low concentration range owing to binding of LA to the serum protein.(ABSTRACT TRUNCATED AT 250 WORDS)


Propofol requirements for induction of anesthesia in children of different age groups. To demonstrate any age-related differences in propofol requirements for induction of anesthesia, 150 healthy children aged 3-5 yr (n = 50), 6-9 yr (n = 50), and 10-15 yr (n = 50) scheduled for outpatient surgery were randomly assigned to receive an induction dose of propofol of 1.5, 2.0, 2.5, 3.0, or 3.5 mg/kg. To limit pain during injection, alfentanil (5 micrograms/kg) was administered before the propofol. Patients were classified as asleep or not asleep 30 s after the propofol. Incidence of excitation, injection pain, and apnea during induction of anesthesia were noted; arterial blood pressure and heart rate were recorded for 5 min after induction. More than 95% of the children were asleep in the dose groups receiving > or = 2.5 mg/kg. The number of patients falling asleep after receiving 1.5 mg/kg of propofol increased significantly with increasing age (P < 0.05); the difference between the oldest and the youngest age groups was the most significant (P < 0.05). Significant decreases in mean arterial blood pressure and heart rate occurred after induction in all dose and age groups without any systematic intergroup differences. Apnea occurred more frequently in older children (P < 0.01) and with larger doses (P < 0.01). The most frequent side effect was erythema near the site of injection, and its occurrence was dose dependent. The authors conclude that 2.5 mg/kg of propofol, if preceded by 5 micrograms/kg of alfentanil, is an appropriate induction dose for children aged 3-15 yr and that the sleep response to 1.5 mg/kg is more in older children.


Effectiveness of preoperative sedation with rectal midazolam, ketamine, or their combination in young children. To determine which of three types of rectal sedation was most effective preoperatively in facilitating parental separation and intravenous cannulation in young children, 100 children 3.0 +/- 1.7 (mean +/- SD) yr of age were randomly assigned to four equal groups. One group (M-K-A) received rectal midazolam (0.5 mg/kg), ketamine (3 mg/kg), and atropine (0.02 mg/kg). The other sedation groups received the same doses of midazolam and atropine (M-A) or ketamine and atropine (K-A) alone, and the control group (A) received only rectal atropine. Most children in either the M-K-A (100%) or M-A (92%) groups separated easily from their parents without struggling or crying, significantly more than in the K-A (60%) or A (64%) groups. However, more children in the M-K-A group (44%) were asleep during separation than in the M-A group (8%; P < 0.05). Only 20% of the children in the M-A or M-K-A groups cried during intravenous catheter placement, significantly less than in the K-A (56%) or A (92%) groups. Intravenous catheter placement was also successful significantly more often in the M-A (80%) and M-K-A (84%) groups than in the K-A (48%) or A (40%) groups. Complications were similar among the groups, but there was evidence that midazolam prolonged recovery time in some patients. Rectal midazolam with or without ketamine is a useful technique when intravenous catheter placement before induction of anesthesia is desired.


Plasma lidocaine concentrations during epidural blockade with isoflurane or halothane anesthesia. Because isoflurane maintains hepatic blood flow at higher flows than halothane, we proposed that the elimination of lidocaine would be different between these two volatile anesthetics. The plasma lidocaine concentrations were determined in 14 female patients undergoing epidural blockade plus isoflurane anesthesia and compared with those obtained during halothane anesthesia for lower abdominal surgery. General anesthesia was maintained with isoflurane (0.46% +/- 0.04% [mean +/- SE] inspired, n = 7) or halothane (0.48% +/- 0.05% inspired, n = 7) and 67% nitrous oxide in oxygen. All patients received 2% lidocaine solution, 10 mL as a bolus dose and continuous administration at a rate of 10 mL/h, through the epidural catheter. The plasma lidocaine concentrations over 180 min after the epidural injection in patients receiving isoflurane were similar to those in patients receiving halothane. The results suggest that low inspired concentrations of isoflurane do not reduce plasma lidocaine concentrations in patients during epidural blockade, compared with halothane.


A rat sciatic nerve model for independent assessment of sensory and motor block induced by local anesthetics. The purpose of this study was to develop a reliable model to independently quantify motor and sensory block produced by local anesthetics. The sciatic nerve was blocked in 52 rats by injecting 0.2 mL of 0.125%, 0.25%, 0.5%, or 0.75% bupivacaine (n = 13 for each concentration). Accurate needle placement was achieved using a nerve stimulator at 0.2 mA and 1 Hz. Ten control rats received 0.9% saline (n = 5) or sham nerve stimulation (n = 5). Motor block was assessed by measuring hindpaw grip strength with a dynamometer. Sensory block was determined by measuring hindpaw withdrawal latency from radiant heat. The intensity of both motor and sensory block measured at 30-min intervals was plotted against time until full recovery to obtain the area under the curve. Intergroup comparisons using analysis of variance showed increasing area under the curve with increasing concentrations of bupivacaine for motor blocks (P < 0.05 for all intergroup comparisons except 0.5% vs 0.75%) and sensory blocks (P < 0.05 for all intergroup comparisons). Normal saline or sham nerve stimulation did not result in any motor or sensory block.


Lumbar subarachnoid ethylenediaminetetraacetate induces hindlimb tetanic contractions in rats: prevention by CaCl2 pretreatment; observation of spinal nerve root degeneration. Disodium ethylenediaminetetraacetate (Na2EDTA) has replaced sodium bisulfite as the antioxidant in 2-chloroprocaine, Nesacaine CE. This study was undertaken to determine whether this new formulation has neurotoxic effects when administered in the subarachnoid space. Sprague-Dawley rats receiving subarachnoid injections of 1.5 mM or higher concentrations of Na2EDTA immediately initiated a circling behavior that was followed by the development of tetanic contractions of the hindlimbs lasting for 15-20 min. The tetanic contractions were followed by a brief period of hindlimb paralysis. Pretreatment of rats by subarachnoid injections of 1 mM CaCl2 prevented the development of tetanic contractions and paralysis of the hindlimb. Histologic examination of animals receiving Na2EDTA revealed moderate to severe focal degenerative changes in spinal nerve roots. Control rats receiving subarachnoid injections of normal saline solution did not develop tetanic contraction nor pathological changes on light microscopy. These results suggest that the preservative used in Nesacaine-MPF may be neurotoxic.


Prolongation of epidural anesthesia using a lipid drug carrier with procaine, lidocaine, and tetracaine. This study evaluated the effect of a lipid drug carrier (iophendylate) on epidural anesthesia. The intensity and duration of motor blockade produced by aqueous and lipid preparations of local anesthetics were assessed in rabbits with long-term indwelling catheters in the epidural space. Motor blockades produced by procaine (1%, 2%, and 4%), lidocaine (1%, 2%, and 4%), and tetracaine (0.5%, 1%, and 2%) in normal saline solution were compared with the effects produced by equimolar amounts of the drug solutions in iophendylate. Procaine (4%) in aqueous solution produced motor blockade lasting 30 +/- 3.54 min (mean +/- SD) versus 84 +/- 4.18 min in lipid solution. Lidocaine (2% and 4%) in aqueous solution produced motor blockade lasting 41 +/- 4.18 and 65 +/- 6.12 min versus 39 +/- 4.18 and 118 +/- 10.1 min, respectively, in lipid solution. Aqueous tetracaine (0.5%, 1%, and 2%) produced motor blockade of 106 +/- 9.62, 189 +/- 6.52, and 273 +/- 26.8 min versus 284 +/- 14.7, 335 +/- 15.8, and 365 +/- 26.9 min, respectively, in their lipid counterparts. A control group of animals that received normal saline solution or iophendylate alone did not exhibit motor blockade. These results may be attributed to sustained release of local anesthetics from the lipid vehicle. Hence, lipid drug carriers may be effective in prolonging epidural anesthesia.


Subblocking concentrations of local anesthetics: effects on impulse generation and conduction in single myelinated sciatic nerve axons in frog. Phenomena seen in axons exposed to subblocking doses serve as the basis for interpreting clinical and behavioral observations during onset and recovery of peripheral nerve block. To delineate the changes in excitability and in impulse conduction caused by subblocking concentrations of local anesthetics (LAs) in myelinated peripheral nerve fibers, LAs were applied to excised frog sciatic nerves while impulse conduction was monitored in single axons. For concentrations ranging from 0.01 to 1.2 times the LA concentration needed to block impulse conduction, three measures of susceptibility to LA were made to quantify the action of the drugs on "resting" fibers (firing rates < or = 0.5 Hz): the increase in the threshold for electrical activation of impulses, the increase in conduction latency reflecting the slowing of impulse conduction in the region exposed to LA, and the "critical blocking concentration" of LA just sufficient to prevent impulse conduction in the recorded fiber. Wide interfiber variation in these variables was observed (e.g., for lidocaine, latency increases at block ranged from 66% to 257% of control, blocking concentrations ranged from 0.29 to 1.40 mM), which was not correlated with fiber diameter (as indicated by resting conduction velocity). Mathematical modeling of impulse conduction in fibers exposed to LA demonstrated that the interfiber variation in susceptibility to LA block could result from interfiber differences in the density of sodium and potassium channels. The effects of LA were also studied in active fibers (firing rates > 0.5 Hz). Local anesthetics reversibly inhibited two normally occurring afteroscillations in membrane threshold related to afterpotentials following an impulse. These were "superexcitability," a transient lowering of threshold lasting as long as 1 s, and "depression," a phase of raised threshold peaking within 2-4 s after an impulse and recovering slowly over several minutes. Impulse activity also transiently increased the apparent potency of LAs. Such "use-dependent" increases in threshold and decreases in conduction velocity showed kinetics that were agent specific, lasting 1 s after a burst of impulses for lidocaine and lasting > 10 s for bupivacaine. At low concentrations, within the range of nontoxic plasma concentrations after systemic administration, the predominant actions of LAs on conducting fibers were transient decreases in excitability and conduction velocity in combination with a reduction of intrinsic oscillatory aftereffects of impulse discharge. These effects may degrade decoding of information in discharge patterns without actually blocking conduction of infrequent impulses, suggesting how functional blockade of coordinated movement and perception may occur even without complete blockade of impulse conduction.


Central nervous system toxicity of local anesthetic mixtures in the rat. Local anesthetics are often administered as mixtures during regional anesthesia. This study investigated whether a synergistic or antagonistic interaction between amide/amide or amide/ester local anesthetic combinations is present with respect to central nervous system toxicity. For surgical preparation, rats were anesthetized with 0.8% halothane in 30% O2/balance N2O and mechanically ventilated. Mean arterial blood pressure and the electroencephalogram were continuously monitored. After surgery, the halothane was discontinued for 15 min. An intravenous infusion of solutions containing lidocaine alone, bupivacaine alone, or any of three mixtures of the two drugs was then begun and continued at a fixed rate until seizure activity was observed on the electroencephalogram. Total administered doses of both drugs were compared by isobolographic analysis. After a similar protocol, a second experiment was performed evaluating lidocaine, tetracaine, or any of three mixtures of those two drugs. In both experiments, normocapnia, normoxia, and normothermia were maintained for all rats. For mixtures of lidocaine/bupivacaine (P = 0.40) and lidocaine/tetracaine (P = 0.24), there was no evidence that a significant degree of either synergism or antagonism was present. At the onset of seizures, mean arterial pressure was lowest in the lidocaine-alone groups in both experiments. Increasing doses of either bupivacaine or tetracaine (with correspondingly decreasing doses of lidocaine) were associated with greater mean arterial pressure values at onset of seizures. We conclude that central nervous system toxic effects of amide/amide or amide/ester anesthetic combinations, such as might occur during accidental intravascular injection, are no more than when the drugs are administered alone.(ABSTRACT TRUNCATED AT 250 WORDS)


Locomotor activity after recovery from hypnosis: midazolam-morphine versus midazolam. This study was performed to test the hypothesis that sedation after recovery from pharmacologic hypnosis is less pronounced if hypnosis is induced with a midazolam-morphine combination compared with midazolam administered alone. Loss of the righting reflex was used as an index for the hypnotic effect and reduction of locomotor activity as an index for the sedative effect. One group of rats received midazolam (20 mg/kg i.v) and another group an equipotent (in relation to the hypnotic ef.fect) combination of midazolam (4 mg/kg i.v.) and morphine (1.3 mg/kg i.v.). The duration of loss of the righting reflex in the midazolam and midazolam-morphine groups was 30 +/- 3 and 28 +/- 2 min, respectively (mean +/- SE). The difference between the groups in locomotor activity after recovery from hypnosis was very pronounced. The locomotor activity in the midazolam-morphine group at 1 and 2 h was seven and five times greater, respectively, than in the midazolam group (P < 0.005). The profound difference in locomotor activity for the two treatment groups was explained on the basis of the difference in the outcomes of midazolam-morphine interactions with regard to hypnosis (synergism) and sedation (summation). When the animals recovered from hypnosis, the synergism of the drug interaction ceased to be a contributing factor.


Thermoregulatory vasoconstriction during propofol/nitrous oxide anesthesia in humans: threshold and oxyhemoglobin saturation. To determine the thermoregulatory effects of propofol and nitrous oxide, we measured the threshold for peripheral vasoconstriction in seven volunteers over a total of 13 study days. We also evaluated the effect of vasoconstriction on oxyhemoglobin saturation (SpO2). Anesthesia was induced with an intravenous bolus dose of propofol (2 mg/kg), followed by an infusion of 180 micrograms.kg-1 x min-1 for 15 min, and maintained with 60% nitrous oxide and propofol (80-160 micrograms.kg-1 x min-1). Central and skin surface temperatures and SpO2 (using two different pulse oximeters) were measured continuously; plasma propofol concentrations and arterial PO2 were measured at 15-min intervals. Volunteers were cooled with a circulating water blanket until definitive peripheral vasoconstriction was detected. The tympanic membrane temperature triggering vasoconstriction was considered the thermoregulatory threshold. Vasoconstriction developed on seven study days during propofol/nitrous oxide anesthesia at a central temperature of 33.3 +/- 1.0 degrees C (mean +/- SD) and plasma propofol concentration of 3.9 +/- 1.1 micrograms/mL. The thresholds during anesthesia were significantly lower than those during the control period (36.7 +/- 0.3 degrees C), but the correlation between plasma propofol concentrations and vasoconstriction thresholds was poor. On the remaining six study days, vasoconstriction did not develop despite central temperatures ranging from 32.1 to 32.7 degrees C. Corresponding propofol concentrations were 4.1-10.9 micrograms/mL. These data suggest that anesthesia with propofol, in typical clinical concentrations, and 60% nitrous oxide substantially inhibits thermoregulatory vasoconstriction. Vasoconstriction increased SpO2 by approximately 2% without a significant concomitant change in PO2. The observed increase in SpO2 probably reflects decreased transmission of arterial pulsations to venous blood in the finger.


Alfentanil-induced hypermetabolism, seizure, and histopathology in rat brain. We evaluated the effect of alfentanil on hippocampal glucose utilization and histopathology associated with alfentanil-induced seizures. Three separate experiments were performed. First, anesthetized, paralyzed Long-Evans rats (n = 15; 5 rats per group) were mechanically ventilated and randomly assigned to three groups: (a) control, 70% N2O and 30% O2 continued for 1 h; (b) low-dose alfentanil (150 micrograms/kg i.v. bolus), followed by infusion at 15 micrograms.kg-1 x min-1 for 1 h without N2O; or (c) high-dose alfentanil (1000 micrograms/kg i.v. bolus), followed by infusion at 100 micrograms.kg-1 x min-1 for 1 h without N2O. After 1 h, [6-14C]glucose was injected intravenously for autoradiography. With high-dose alfentanil, there was increased glucose utilization in the ventral hippocampus and the lateral septal nucleus. In the second experiment, anesthetized, paralyzed Sprague-Dawley rats (n = 12; 4 rats per group) were mechanically ventilated, underwent insertion of hippocampal depth electrodes, and were randomly assigned to three groups: (a) control, 70% N2O and 30% O2; (b) low-dose alfentanil (150 micrograms/kg i.v. bolus), with 70% N2O and 30% O2; or (c) high-dose alfentanil (1000 micrograms/kg i.v. bolus), with 70% N2O and 30% O2. An epileptiform pattern was observed on hippocampal and subdermal electroencephalographic recordings in both alfentanil groups. In the third experiment, anesthetized, paralyzed Sprague-Dawley rats (n = 20) were mechanically ventilated and assigned to two groups: (a) control, 70% N2O and 30% O2 (n = 5) or 100% O2 (n = 5) continued for 1 h; or (b) alfentanil (2000 micrograms/kg i.v. bolus), followed by infusion at 33.3 micrograms.kg-1 x min-1 for 1 h with 100% O2. After tracheal extubation, the rats recovered overnight. Light-microscopic evaluation revealed hippocampal or amygdaloid damage in 6 of the 10 alfentanil-treated rats. High doses of alfentanil administered to rats can produce limbic system seizure activity with hypermetabolism associated with neuropathologic lesions.


Time-course of respiratory depression after an alfentanil infusion-based anesthetic. Postoperative respiratory depression after alfentanil administration has been described in several case reports. The effects of a prolonged alfentanil infusion on the CO2 response curve or cognitive function have not been studied. Twenty-one ASA physical status I or II patients were studied after a prolonged alfentanil infusion (> 90 min) to determine the incidence of postoperative respiratory depression, arterial O2 desaturation, and impairment of cognitive function. Each patient's recovery was observed at 30-min intervals for evidence of respiratory depression (utilizing the Read CO2 rebreathing method), desaturation by pulse oximetry (severe desaturation defined as arterial O2 saturation < 90%), and cognitive function (utilizing Trieger dot and digit substitution tests). Plasma samples were also examined for secondary elevations in alfentanil plasma concentrations. Significant depression of the CO2 response curve and cognitive function was found up to 1 h postoperatively. Arterial O2 desaturation was seen in 11 of 21 patients (52%). No correlation was found between arterial O2 desaturation and cognitive function scores or CO2 rebreathing results. Increased depression of the CO2 response curve was not necessarily associated with severe desaturation episodes. A secondary increase in plasma alfentanil concentration was detected in 5 of the 21 patients (24%), but these patients did not experience further depression of the CO2 response curve. We conclude that prolonged alfentanil administration may result in severe arterial O2 desaturation with significant depression of the hypercapnic respiratory drive during the first hour in the postanesthesia care unit, even though the majority of our patients were easily aroused in response to verbal stimuli.


R-phenylisopropyl-adenosine increases spinal cord blood flow after intrathecal injection in the rat. The A1-adenosine receptor agonist, R-phenylisopropyl-adenosine (R-PIA), demonstrated antinociceptive properties in animal studies after intrathecal administration. In the evaluation of a drug for possible spinal injection in humans, the effects of intrathecal R-PIA on spinal cord blood flow (SCBF) were investigated using the laser-Doppler flow-metry technique in anesthetized rats. In low doses (0.1-1 nmol), no change in SCBF was recorded, whereas larger doses (10-100 nmol) caused a significant increase in SCBF. No change in systemic arterial blood pressure could be seen, except for a decrease after administration of the largest dose of R-PIA (100 nmol). It is concluded that R-PIA in doses of 10 nmol and larger induces an increase in SCBF after intrathecal injection in anesthetized rats and that an increase in blood flow is seen before any effect on the systemic circulation is detected. It can also be deduced that the antinociceptive effects of R-PIA after intrathecal injection are not a consequence of spinal ischemia and that disturbances in local blood flow cannot be expected to constitute a neurotoxic factor.


Changes in functional residual capacity and regional diaphragm lengths after upper abdominal surgery in anesthetized dogs. The respiratory performance of the diaphragm may be altered by changes in mechanical or neural factors, or both, induced by upper abdominal surgery. We conducted this study to examine the effects of upper abdominal surgery on postoperative respiratory function. We studied resting lengths of four diaphragm regions, three in the costal and one in the crural diaphragm, with biplane video-roentgenography in six dogs immediately after upper abdominal surgery and up to 30 days postoperatively. Functional residual capacity was 16.7% smaller immediately after surgery compared with values obtained in the same animals after 30 days. Simultaneously measured resting lengths of each of the diaphragm regions immediately after surgery were longer, on average by 8.3%, than 30 days postoperatively. During the postoperative course, resting diaphragm lengths gradually and uniformly decreased as functional residual capacity increased. Phrenic nerve stimulation in four other dogs immediately after identical surgery resulted in large diaphragm shortening (from 42% to 55%), indicating that neither the diaphragm nor phrenic nerves were injured by the surgical manipulation. We hypothesize that respiratory dysfunction after upper abdominal surgery may be, at least in part, attributed to a decreased central drive for breathing caused by activation of the afferent limb of an inhibitory reflex owing to stretching of the diaphragm.


Direct measurement of nitrous oxide MAC and neurologic monitoring in rats during anesthesia under hyperbaric conditions. The minimum alveolar concentration (MAC) of nitrous oxide necessary to prevent purposeful movement in rats has not been directly measured; rather, it has been extrapolated because the required partial pressure exceeds 760 mm Hg, or 1 atm absolute pressure (ATA). Values reported have ranged from 1.36 to 2.20 ATA (136-220 vol%, or 1034-1672 mm Hg). By maintaining general anesthesia at 2.25 ATA (1710 mm Hg), we directly measured the nitrous oxide MAC in 17 Long-Evans rats during mechanical ventilation and monitoring of two-channel electroencephalogram, compressed spectral array and cortical evoked potentials, electrocardiograph, and respiratory and anesthetic gases by mass spectrometry. After a minimal stabilization period of 30 min during ventilation by 1.8 ATA nitrous oxide and 0.45 ATA oxygen, MAC measurements were begun. Each rat was given up to three noxious electrical stimulations of 50 V by 10-ms-duration pulses at 50/s for 45 s. The partial pressure of nitrous oxide was decreased by approximately 10% after each negative response. The MAC was taken as the nitrous oxide concentration midway between that at which there was no response and that at which the rat moved purposefully. The nitrous oxide MAC in Long-Evans rats was determined to be 1.55 +/- 0.16 ATA (mean +/- SD). Hyperbaric nitrous oxide decreased electroencephalogram wave frequency to a predominantly theta rhythm of increased amplitude. Cortical evoked potentials had decreased wave amplitudes and increased latencies with increasing partial pressures > 0.75 ATA.(ABSTRACT TRUNCATED AT 250 WORDS)


A comparative study of blood warmer performance. Massive transfusions of refrigerator-temperature blood may induce hypothermia and life-threatening arrhythmias; for this reason a variety of devices have been developed for rapid blood warming. Blood warmers available in the United States use one of three warming technologies: dry heat, water bath, or countercurrent heat exchange. In the current study we evaluated blood warmers representative of each technology for speed and extent of heat transfer: the Fenwal blood warmer (Fenwal Laboratories; dry heat), the DW-1000 (American Pharmaseal Co.; dry heat), the FloTem IIe (DataChem Inc.; dry heat), the Hemokinetitherm (Dupaco Inc.; water bath), and the H250 and H500 (Level 1 Technologies; countercurrent heat exchange). Only one countercurrent heat instrument (the H500) was able to heat blood > or = 33 degrees C at target flow rates > or = 250 ml/min. Dry heat and water bath blood warmers were unable to warm blood > or = 33 degrees C at target flow rates > or = 100 ml/min. High resistance to flow with the proprietary tubing required for one instrument (the Hemokinetitherm) prevented tests of blood warming at rates > 150 ml/min. We found that instruments that used countercurrent technology warmed blood and saline more effectively than did blood warmers that used either dry heat or water bath technology. Our study also demonstrated the need for close control and standardization of experimental conditions in the evaluation of blood warming devices.


Use of the laryngeal mask airway as an alternative to a face mask during outpatient arthroscopy. The laryngeal mask airway (LMA) has recently become available in the United States, and several authors have suggested that it is superior to an anesthesia mask. To test this hypothesis, 64 patients undergoing outpatient arthroscopic knee surgery were randomly assigned to have anesthesia maintained via either a laryngeal mask airway (LMA) (n = 31) or a standard face mask (n = 33). Anesthesia was induced with fentanyl 1 microgram.kg-1 and propofol 2 mg.kg-1 and maintained with a variable-rate propofol infusion (50-180 micrograms.kg-1 x min) and nitrous oxide 67% in oxygen. The LMA was inserted without difficulty by inexperienced anesthesiologists in 90% of the patients. Problems associated with airway management were more common in patients in the face mask (control) group. Episodes of hemoglobin oxygen desaturation (< 95%) occurred in 52% of patients in the face mask group compared to only 13% in the LMA group (P < 0.05). Intraoperative airway manipulations were required in 15% of face mask patients (vs. 3% of the LMA group), and difficulties in maintaining an airway were reported by 24% of the resident anesthesiologists caring for patients in the face mask group (vs. none in the LMA group) (P < 0.05). Insertion of the LMA was not associated with any acute changes in hemodynamic values. Intraoperative hemodynamic values and anesthetic requirements did not differ significantly between the two treatment groups. There were no significant differences in the emergence and recovery times or in the incidence of postoperative sore throats between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)


Clinical trials of an intravenous oxygenator in patients with adult respiratory distress syndrome. In patients with severe adult respiratory distress syndrome, mechanical ventilation may not be able to ensure gas exchange sufficient to sustain life. We report the use of an intravenous oxygenator (IVOX) in five patients who were suffering from severe adult respiratory distress syndrome as a result of aspiration, fat embolism, or pneumonia. IVOX was used in an attempt to provide supplemental transfer of CO2 and O2 and thereby reduce O2 toxicity and barotrauma. All patients were tracheally intubated, sedated, and chemically paralyzed and had a PaO2 < 60 mmHg when the lungs were ventilated with an FIO2 = 1.0 and a positive end expiratory pressure of > or = 5 cmH2O. The right common femoral vein was located surgically, and the patient was systemically anticoagulated with heparin. A hollow introducer tube was inserted into the right common femoral vein, and the furled IVOX was passed into the inferior vena cava and advanced until the tip was in the lower portion of the superior vena cava. IVOX use ranged from 2 h to 4 days. In this group of patients, IVOX gas exchange ranged from 21 to 87 ml x min-1 of CO2 and from 28 to 85 ml x min-1 of O2. One of the five patients survived and was discharged from the hospital. The IVOX transferred up to 28% of metabolic gas-exchange requirements. One patient with a small vena cava showed signs of caval obstruction. Three other patients demonstrated signs of a septic syndrome after the device was inserted.(ABSTRACT TRUNCATED AT 250 WORDS)


Clonidine reduces sympathetic activity but maintains baroreflex responses in normotensive humans. Clonidine, an alpha 2-adrenergic agonist, has been shown to modify the hemodynamic responses to surgery. To examine further the mechanism underlying this action, we evaluated the neurocirculatory effects of oral clonidine and the ability of clonidine to alter the hemodynamic and sympathetic responses to a noxious stimulus (cold pressor test) and to baroreceptor perturbations in nine healthy men (ages 20-29 yr). Heart rate (ECG), blood pressure (radial artery catheter), central venous pressure (jugular vein), and cardiac output (impedance cardiography) were monitored before and after oral clonidine (0.3 mg) or placebo. Plasma norepinephrine was measured with high-performance liquid chromatography. Sympathetic nerve activity (SNA) to skeletal muscle blood vessels was recorded from a Tungsten needle positioned within the peroneal nerve. Baroreceptor testing was carried out by intravenous bolus injections of nitroprusside (100 micrograms) followed 60 s later by intravenous phenylephrine (150 micrograms). The slope of the linear relationship between the change in R-R interval versus the change in mean pressure (cardiac baroslope) or change in SNA versus change in diastolic pressure (sympathetic baroslope) was determined at baseline and 75 min after clonidine or placebo. In addition, peak responses to the cold pressor test (60-s hand immersion in ice water) were determined at the same intervals. Clonidine progressively decreased blood pressure and muscle SNA over the 75-min session. Clonidine subtly reduced the sympathoexcitation produced by the cold pressor test but did not alter the gain of the baroreceptor reflex regulating cardiac interval or peripheral SNA; baroslope relationships were simply shifted leftward (to operate at lower pressures).(ABSTRACT TRUNCATED AT 250 WORDS)


The influence of propofol with and without nitrous oxide on cerebral blood flow velocity and CO2 reactivity in humans. The cerebrovascular response to CO2 has been reported to be preserved during propofol anesthesia, but no comparison with awake control values has been made, and the additional influence of N2O has not been investigated. Using the noninvasive technique of transcranial Doppler ultrasonography, this study investigated the cerebrovascular response to varying levels of PaCO2 while awake and during anesthesia with propofol and propofol/N2O. Seven adults without systemic diseases undergoing nonneurologic surgery were studied. A pulsed-wave Doppler monitor was used to measure the mean middle cerebral artery flow velocity (Vmca) during varying levels of PaCO2 (25-55 mmHg) under the following conditions: 1) awake; 2) propofol 2.5 mg.kg-1 bolus followed by continuous infusion of 150 micrograms.kg-1.min-1; and 3) propofol as in the condition above plus 70% N2O. During the awake study condition, hypocapnia was induced by voluntary hyperventilation, and hypercapnia was induced with rebreathing of 7% CO2 in a closed circuit. During the anesthetized study conditions, hypocapnia and hypercapnia were induced by adjustment of minute ventilation. A minimum of five to six simultaneous Vmca and PaCO2 measurements were obtained under each of the study conditions. Systemic blood pressure was monitored via a radial arterial catheter, and phenylephrine was administered if mean arterial blood pressure decreased below 60 mmHg (phenylephrine was used in three of five patients in the propofol-N2O group). Linear regression and analysis of covariance were used for statistical analysis of Vmca-PaCO2 relationships.(ABSTRACT TRUNCATED AT 250 WORDS)


Inhaled nitric oxide after mitral valve replacement in patients with chronic pulmonary artery hypertension. Patients with mitral valve disease can develop pulmonary artery hypertension that persists after mitral valve replacement. In 1987, nitric oxide (NO) was reported to be an important factor accounting for the biologic activity of endothelium-derived relaxing factor. Inhaled NO was subsequently reported to be a selective pulmonary vasodilator in animals and patients. Therefore we investigated the vasodilating effect of inhaled NO in patients with mild pulmonary artery hypertension after mitral valve replacement. Six patients who underwent mitral valve replacement for mitral stenosis presented with a mean pulmonary artery pressure greater than 25 mmHg within 24 h after surgery. During mechanical ventilation at FIO2 0.5, NO (36.8-38.4 ppm) was breathed for 10 min. Hemodynamic data were recorded before NO, after 10 min of NO inhalation, and 30 min after the end of NO inhalation. Statistically significant (P < 0.05) hemodynamic response to inhaled NO included a transient decrease in systolic (-10%), diastolic (-8%), and mean (-10%) pulmonary artery pressures; a decrease in pulmonary vascular resistance (-22%); an increase in mixed venous hemoglobin O2 saturation (+6%); and a decrease in arteriovenous O2 content difference (-7%). During NO inhalation, there was no change in systemic arterial or pulmonary wedge pressures. Methemoglobin levels remained < 1%. Inhalation of this concentration of NO for 10 min causes transient pulmonary artery vasodilation and hemodynamic improvement in patients with mild chronic pulmonary artery hypertension after mitral valve replacement.


A comparison of intrathecal, epidural, and intravenous sufentanil for labor analgesia. A number of recent studies have suggested that the analgesic effects of highly lipid-soluble opioids are similar when these agents are administered either epidurally or intravenously. We sought to test whether the lipid-soluble opioid sufentanil was more effective when administered intrathecally than when administered epidurally or intravenously. Twenty-four women during active labor received sufentanil 10 micrograms either intrathecally (n = 9), epidurally (n = 8), or intravenously (n = 7), using a combined spinal-epidural technique. The sufentanil was administered alone, without concomitant local anesthetics. Analgesia was assessed using the visual analogue score as well as the time elapsed from the administration of study drug to the patient's request for additional analgesia via the epidural catheter (bupivacaine 0.25%). The median duration of analgesia (median, interquartile range) was 84 (70-92) min in the intrathecal group, 30 (23-32) min in the epidural group, and 34 (17-30) min in the intravenous group (P < 0.001). The intrathecal group showed rapid and significant decrease in visual analogue scale scores, whereas visual analogue scale scores in the other two groups did not decrease and remained significantly elevated compared to those of the intrathecal group at all observation points. Side effects were limited to pruritus in 3 patients (2 moderate and 1 severe) in the intrathecal group. No patient developed post-dural puncture headache. We conclude that sufentanil 10 micrograms intrathecally provides rapid and effective analgesia of 1-2-h duration during labor. Epidural and intravenous use of this dose of sufentanil did not provide evidence of satisfactory analgesia.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of isoflurane and nitrous oxide in subanesthetic concentrations on memory and responsiveness in volunteers. Awareness, defined as conscious memory during anesthesia, has been a problem in anesthesia practice. To determine the effect of isoflurane and nitrous oxide (N2O) on memory, 17 healthy adult volunteers were randomly assigned to receive isoflurane or N2O and received the alternate agent 1-2 weeks later. Each volunteer was studied at four end-tidal concentrations of each agent, consecutively 0.15, 0.3, 0.45, and 0.15 times the minimum alveolar concentration (MAC) for isoflurane or 0.3, 0.45, 0.6, and 0.3 times MAC for N2O. After 15-min equilibration at each end-tidal concentration, volunteers were tested for voluntary response to command and were presented with verbal information to be recalled after anesthesia. Volunteers were interviewed on the day after the study and tested for conscious and unconscious memory of the information presented during anesthetic administration. MAC-awake (the end-tidal concentration preventing voluntary response in 50% of volunteers) was 0.38 (0.35-0.42) times MAC for isoflurane and 0.64 (0.61-0.68) MAC for N2O (means, 95% confidence limits), indicating isoflurane to be more potent than N2O in suppressing voluntary response (P = .0001). Memory data were analyzed in 12 volunteers who completed the study and in whom the allocation of information to be recalled was counterbalanced among agents and concentrations of agents. Memory was decreased by increasing concentrations of both agents. Conscious memory of the information presented during anesthetic administration was prevented by 0.45 MAC isoflurane but not completely prevented by 0.6 MAC N2O. Unconscious memory (defined as memory of information without conscious recognition) occurred during administration of both agents and was prevented by 0.45 MAC isoflurane but not by 0.6 MAC N2O. Isoflurane was more potent in suppressing memory than MAC-equivalent concentrations of N2O. Using models of the relationship between dose of agent and suppression of memory, a dose of both agents was estimated that suppressed memory by 50% (ED50). The ED50 was 0.20 MAC for isoflurane (95% confidence intervals, 0.15-0.25), and 0.50 MAC for N2O (95% confidence intervals 0.43-0.55). We conclude that isoflurane and N2O suppress memory in a dose-dependent manner, and that isoflurane is more potent in preventing memory and voluntary response to command than MAC-equivalent concentrations of N2O.


Pharmacokinetics of rocuronium bromide (ORG 9426) in patients with normal renal function or patients undergoing cadaver renal transplantation. To determine the effect of end-stage renal disease on the pharmacokinetics of reocuronium bromide (ORG 9426), a new nondepolarizing monoquaternary steroidal neuromuscular blocking drug, the authors administered 600 micrograms/kg rocuronium (2 x ED95) intravenously to ten patients undergoing cadaver renal transplantation and ten healthy patients undergoing elective minor surgery (controls). All patients were anesthetized with nitrous oxide (50-70% in oxygen) and isoflurane (end-tidal concentrations of 1.2 +/- 0.5% and 0.8 +/- 0.2%, mean +/- SD, for control and transplant groups, respectively). Plasma concentrations of rocuronium were determined by capillary gas chromatography. A population-based pharmacokinetic analysis (NONMEM) was used to determine typical values, standard errors, and interindividual variability for the pharmacokinetic parameters and to determine whether these values differed between control and renal transplant patients. Total plasma clearance (2.89 +/- 0.25 ml.kg-1.min-1, mean +/- SE) and volume of the central compartment (76.9 +/- 10.6 ml/kg) did not differ between control and renal transplant patients, whereas volume of distribution at steady state was greater in renal transplant patients (264 +/- 19 ml/kg) than in control patients (207 +/- 14 ml/kg). This resulted in a longer elimination half life in renal transplant patients (97.2 +/- 17.3 min) compared to controls (70.9 +/- 4.7 min). The authors conclude that renal failure and renal transplantation alter the distribution but not the clearance of rocuronium.


Prevalence of latex sensitization among hospital physicians occupationally exposed to latex gloves. Patients undergoing surgery who have a history of occupational exposure to latex gloves may be predisposed to intraoperative anaphylaxis caused by latex allergy. Thus, medical personnel who routinely wear latex gloves may be at higher risk than the general population. The prevalence of latex sensitization has not been reported previously among physicians using latex gloves in a North American hospital setting. Using a latex skin prick test (SPT), we determined the prevalence of latex sensitization among 101 staff anesthesiologists, radiologists, and surgeons who regularly use latex gloves and among 100 atopic controls who were not occupationally exposed to latex gloves. Latex SPT was positive in 10 of 101 physicians (rho = 0.099; 95% confidence interval [CI] 0.041, 0.157) and 3 of 100 controls. Subgroup analysis showed that 9 of 38 atopic physicians were SPT-positive (rho = 0.237; 95% CI 0.102, 0.372). Atopic physicians were more likely to be latex SPT-positive than either nonatopic physicians or atopic controls (atopic vs. nonatopic physicians: P = 0.0006, odds ratio = 19.2, 95% CI 15.4, 23.1; atopic physicians vs. atopic controls: P = 0.0005, odds ratio = 9.1, 95% CI 7.5, 11.6). We conclude that compared to nonatopic physicians exposed to latex, or nonexposed atopic controls, atopic physicians who wear latex gloves are at increased risk of latex allergy.


Respiratory interaction after spinal anesthesia and sedation with midazolam. The combined use of midazolam and spinal anesthesia is common in clinical practice. Despite the known potential for each to alter ventilation, the effect of their interaction has not been examined. Nineteen healthy volunteers were studied to assess the impact of intravenous midazolam (0.05 or 0.075 mg/kg), spinal anesthesia (T3-T8; mean level, T6), and their combination on resting ventilation and ventilatory responses to progressive hyperoxic hypercapnia. Resting ventilatory pattern was altered significantly by each condition. Midazolam caused a 29% decrease in resting tidal volume and a 24% decrease in mean inspiratory flow rate, while respiratory frequency increased by 14% and minute ventilation remained unchanged. By contrast, spinal anesthesia alone caused a 32% increase in tidal volume, a 24% increase in mean inspiratory flow rate, and a 13% increase in minute ventilation accompanied by a 14% decrease in respiratory frequency. The combination of midazolam and spinal anesthesia caused a significant decrease in minute ventilation (19%), tidal volume (28%), and mean inspiratory flow rate (27%), all of which were significantly more than the predicted sum of the individual interventions. Midazolam and spinal anesthesia each produced a significant decrease in hypercapnic ventilatory response slope, whereas their combination provoked no net change in hypercapnic ventilatory response slope. Interpretation of the hypercapnic ventilatory response data was complicated by shifts in the position of the ventilatory response curve, particularly under the spinal anesthesia condition. It is concluded that intravenous midazolam depresses resting ventilation, spinal anesthesia stimulates resting ventilation, and their combination has a modest synergistic effect of depressing resting ventilation.


The antiemetic effect of lorazepam after outpatient strabismus surgery in children. The high incidence of postoperative emesis after strabismus surgery in pediatric outpatients can be reduced by the prophylactic administration of droperidol 75 micrograms/kg intravenously. However, this may be associated with profound sedation, delayed discharge, dysphoria, agitation, and extrapyramidal symptoms in this population. Because lorazepam used as an antiemetic in children during chemotherapy decreased the incidence of nausea and vomiting, we compared the antiemetic effects of lorazepam and droperidol in a randomized, double-blind, placebo-controlled study of 129 healthy children undergoing surgical correction of strabismus. The children, aged 1-13 yr, were randomly allocated into three groups. The children in group 1 received droperidol 75 micrograms/kg intravenously; those in group 2 received lorazepam 10 micrograms/kg intravenously; and those in group 3 received placebo. Anesthesia consisted of halothane, nitrous oxide in oxygen, and atracurium. Study drugs were administered intravenously after induction of anesthesia but before surgery. In children 3-13 yr old, administration of either lorazepam or droperidol was associated with a lower (P < 0.024) incidence of postoperative vomiting. There was no difference between the antiemetic effect of lorazepam and that of droperidol. The incidence of postoperative agitation was greater in the droperidol group (P < 0.001) than in the lorazepam and placebo groups. Postdischarge vomiting was less (P < 0.009) in children younger than 3 yr of age. Lorazepam, similar to droperidol, has an antiemetic effect in outpatient children 3-13 yr old undergoing strabismus correction, but it is associated with less postoperative agitation than is droperidol.


No correlation between quantitative electroencephalographic measurements and movement response to noxious stimuli during isoflurane anesthesia in rats. A meaningful use of the electroencephalogram (EEG) for monitoring depth of anesthesia has proven elusive. Although changes in the EEG with changing anesthetic dose or concentration have been noted for 60 yr, it has been difficult to demonstrate reliable, quantitative correlation between the EEG and other physiologic measures of anesthetic depth. We attempted to correlate several quantitative EEG measurements in rats, including average amplitude, spectral edge frequency, and burst suppression ratio, with the movement response to supramaximal noxious stimulation. We anesthetized 21 Sprague-Dawley rats with isoflurane 1.5% and allowed them to breathe spontaneously. After equilibration, EEG was recorded for off-line analysis; then a noxious stimulation was delivered with a tail clamp and the somatic response noted. Isoflurane concentration was adjusted up and down, and the EEG and movement response to tail clamp were assessed at each level until the minimum alveolar concentration was determined in each rat. We found no EEG dose response to increasing inspired concentrations of isoflurane, except for an increasing degree of burst suppression. We found no difference in any parameter between rats that responded and those that did not respond to stimuli at a given concentration of isoflurane. Finally, we found that the presence of burst suppression did not predict lack of response.


The general anesthetic potency of propofol and its dependence on hydrostatic pressure. Although plasma concentrations of propofol during anesthesia are well known, the free concentration remains unknown because of uncertainties regarding plasma protein binding, interaction with other protein-bound substances, the level of binding to its lipid carrier, and the use of adjuvants. At elevated surrounding pressure, all general anesthetics require higher concentrations to reach adequate levels of anesthesia. To determine the anesthetic potency of propofol at equilibrium conditions and to study the effects of pressure on propofol-induced anesthesia, Rana pipiens tadpoles were exposed to different concentrations of pure, not emulsified, propofol in aqueous solution. Anesthesia was defined as loss of the righting reflex. Ten animals per concentration were used, and each experiment was conducted twice. Pressure experiments were performed with nonanesthetized tadpoles and urethane-anesthetized tadpoles as control groups. Propofol concentrations were measured spectrophotometrically. At 1 atmosphere absolute (atm abs), a semilogarithmic sigmoidal concentration-response curve was obtained with a half-maximal effect of propofol at 2.2 +/- 0.22 microM (EC50; mean +/- SE). Increased pressure shifted the concentration-response curve to the right. The EC50 increased linearly with increasing pressure up to 121 atm abs (EC50 at 121 atm abs = 4.1 +/- 0.41 microM). For pressure greater than 121 atm abs, an increased excitability of the tadpoles made it difficult to distinguish the righting reflex from involuntary movements. The saturated solubility of propofol in aqueous solution was found to be 1.0 +/- 0.02 mM (mean +/- SD), and the octanol/water partition coefficient was 4,300 +/- 280. Propofol adhered to the correlation between anesthetic potency and octanol/water partition coefficient exhibited by other general anesthetics.(ABSTRACT TRUNCATED AT 250 WORDS)


Local anesthetic-induced conduction block and nerve fiber injury in streptozotocin-diabetic rats. Patients with diabetes may have peripheral neuropathy, which may have clinical implications for the use of regional nerve block. The effects of local anesthetics on nerve conduction and nerve fiber injury were tested in control rats and at 4 weeks after the onset of diabetes in rats injected with streptozotocin (50 mg/kg intraperitoneally). Nerve conduction was assessed by recording evoked electrical activity in hindpaw muscles following ipsilateral electrical stimulation of the sciatic nerve near the hip. Block of motor nerve conduction was quantified by recording the amplitude of the evoked response at 1-min intervals for up to 15 min after the injection of 500 microliters 1% lidocaine HCl or procaine HCl into the midthigh next to the sciatic nerve. In control animals, procaine was much less effective than lidocaine in producing conduction block. The rate and magnitude of lidocaine-induced conduction block were not significantly different between control and diabetic groups. However, conduction block due to procaine was sufficiently enhanced in diabetic rats to become comparable to that of lidocaine-treated control nerves. Long-lasting injury was assessed in sciatic nerve harvested 2 days after the extraneural injection of saline or 2 or 4% lidocaine HCl. Using a light microscope with a superimposed grid, nerve edema was quantified as the proportion of intersection points falling on extracellular space. Lidocaine induced edema in both control and diabetic nerves, but 4% lidocaine induced significantly more edema in diabetic nerves than in controls. Nerve fiber injury, based on light microscopic scoring of axonal degeneration and demyelination, was not observed in saline-treated nerves.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of propofol and thiopental in isolated rat aorta and pulmonary artery. This study was performed to determine if direct arterial dilating actions of propofol contribute to the drug's hypotensive actions. The effects of propofol were compared with those of thiopental on isolated vascular ring preparations from rat thoracic aorta and pulmonary artery. Thoracic aortic ring responses were evaluated in the presence and absence of endothelium, indomethacin, and N omega-nitro-L-arginine methyl ester (LNAME; a specific inhibitor of endothelium-derived relaxing factor-nitric oxide [EDRF/NO] synthase). Pulmonary artery responses were investigated with intact endothelium. After the induction of active isometric force by a predetermined EC50 dose of phenylephrine for each ring, effects of propofol (30, 100, 300 microM) and thiopental (10, 30, 100 microM) were examined. Propofol caused significant vasodilation in endothelium-intact, endothelium-denuded, and LNAME-treated aortic rings. In the endothelium-intact aortic and pulmonary artery rings, the initial vasodilation due to 30 and 100 microM propofol showed gradual and partial recovery over 15 min; 300 microM propofol caused sustained vasodilation. Endothelium-denuded rings and LNAME-pretreated endothelium-intact rings showed constant and sustained vasodilation with all propofol concentrations. Propofol also caused marked vasodilation in pulmonary arteries. In contrast, thiopental had no vasodilating effect in aortic or pulmonary artery preparations. In control experiments, propofol vehicle (Intralipid) also had no effect on vascular rings. Indomethacin pretreatment induced a dose-dependent vasoconstriction by thiopental in endothelium-intact rings and decreased the vasodilation due to propofol.(ABSTRACT TRUNCATED AT 250 WORDS)


Direct effects of propofol on myocardial contractility in in situ canine hearts. The pronounced decrease in arterial blood pressure evident during anesthetic induction with propofol has raised the possibility that propofol has a direct negative inotropic effect. Previous attempts to evaluate this mechanism in vivo have been inconclusive because of confounding variables associated with intravenous administration of propofol. Accordingly, in the current study, steady-state changes in myocardial contractility and related hemodynamic parameters were assessed during intracoronary infusions of propofol in seven open-chest dogs anesthetized with fentanyl and midazolam. The left anterior descending coronary artery (LAD) was cannulated and perfused at controlled pressure (100 mmHg) with normal arterial blood. In LAD-perfused myocardium, contractility was evaluated from measurements of percent segmental shortening (%SS) obtained with ultrasonic crystals. Coronary blood flow in LAD was measured electromagnetically and used to calculate myocardial oxygen consumption (MVO2; Fick principle) and coronary propofol concentration. Propofol was infused into the LAD at 150, 300, 600, and 1,200 micrograms/min (P-150, P-300, P-600, P-1,200). These infusion rates yielded calculated blood concentrations of 7 +/- 1, 15 +/- 1, 26 +/- 2, and 50 +/- 5 micrograms.ml-1, respectively. The calculated blood concentrations at P-150 were in the clinical range, whereas those at P-300, P-600, and P-1,200 were supratherapeutic. P-150 had no effect on %SS, whereas higher infusion rates caused decreases in %SS. Changes in MVO2 by propofol generally paralleled changes in %SS. At P-150 and P-300, coronary blood flow was proportional to MVO2, whereas at P-600 and P-1,200, coronary blood flow was in excess of the prevailing MVO2, resulting in increased coronary venous oxygen tension.(ABSTRACT TRUNCATED AT 250 WORDS)


Sleep disruption and increased apneas after pontine microinjection of morphine. The medial pontine reticular formation (mPRF) is a cholinoceptive brain stem region known to play a key role in regulating rapid eye movement (REM) sleep and state-dependent ventilatory depression. Numerous lines of evidence have shown that opioids inhibit both cholinergic neurotransmission and REM sleep. The present study examined the hypothesis that morphine applied to the cholinoceptive mPRF would inhibit REM sleep and alter ventilation. In six cats, guide cannulas were chronically implanted to permit pontine microinjection of morphine sulfate, naloxone, and the cholinergic agonist carbachol. After each mPRF microinjection, 2-h polygraphic recordings quantified respiratory frequency and the percent of time spent in states of wakefulness, non-REM sleep, and REM sleep. The results show that mPRF administration of morphine significantly inhibited REM sleep and that this REM sleep inhibitory effect was blocked by pretreating the mPRF with naloxone. Apneic episodes were increased after injection of morphine alone, and the apneas were decreased by the cholinergic agonist carbachol. The results also demonstrated that the ability of microinjected morphine to inhibit REM sleep was dose-dependent and site-dependent. Considered together, the site-localization, pharmacologic blocking, and dose-response data support the hypothesis that specific regions of the mPRF can contribute to the long-recognized ability of morphine to inhibit REM sleep and alter respiratory control.


Histologic examination of the rat central nervous system after intrathecal administration of human beta-endorphin. The objective of this study was to evaluate histologically the toxicity of human beta-endorphin on the rat central nervous system after intrathecal administration. Animals received a single injection of 5 micrograms (n = 9) or 50 micrograms (n = 10) on each of four consecutive days, while others received 50 micrograms (n = 8) as a single dose. The control groups received either physiologic saline (n = 10) during each of four consecutive days or had sham operations (n = 4). Tests for nociception (tail-flick latency), motor function, and reflexes (righting reflex, eye-blink reflex, and inclined plane) were performed 5, 15, 30, 60, and 120 min after injection. Both dosages produced a dose-dependent impact on these parameters. In the 50-micrograms group, there were no significant differences in analgesia between the first and the fourth doses injected. The 50-micrograms dose produced catalepsy in some animals. All changes returned to baseline within 24 h. One animal in the 50-micrograms group developed hind limb paralysis after a single injection. Histologic sections from brain, brain stem, and spinal cord were prepared. No changes in histology were found except for that in the paretic animal, which had anoxic changes in the hippocampus and other cortical areas. Human beta-endorphin produced no neurotoxicity. The effect on nociception, reflexes, and motor function confirmed the results of previous studies.


Impact on knowledge and practice of a multiregional long-term care facility infection control training program. Few affordable training opportunities are specifically designed for the long-term care facility infection control practitioner. There is also little evidence of the success of training in improving infection control practices. The Nebraska Infection Control Network developed a 2-day basic skills training program for Midwestern long-term care facility infection control practitioners that was later disseminated to eastern and western training sites. In this study we examined the effectiveness of the training program in terms of trainee knowledge and practice. From 1986 to 1990, a total of 17 courses conducted at the three sites were attended by a total of 266 infection control practitioners. Trainees completed a 40-item multiple choice test before and after training to evaluate their knowledge gain. Implementation of eight key infection control practices and time devoted to infection control duties were measured before training and at 3 and 12 months after training. Implementation of infection control practices was also evaluated in a second study, with infection control practitioners randomly assigned to trained and wait-control conditions. Significant increases after training were found at each site for both knowledge and implementation measures. These increases were maintained at 12 months follow-up. Time devoted to infection control duties increased significantly at the midwest and western sites but not at the eastern site. In the second study, significant differences were found between the trained and the wait-control group in use of infection control practices, providing evidence for a causal relationship between training and increased use of practices. The training program was effective in producing improvements in knowledge and implementation of recommended infection control practices in long-term care facilities. These improvements were consistent across three diverse geographic areas. There were some specific geographic differences.