Epicardial cryoablation of myocardial tissue using endocardial thermal isolation. Surgical cure of right atrial arrhythmias may be accomplished by excision, exclusion, or cryoablation of the arrhythmogenic focus. Cryoablation may be performed epicardially without cardiopulmonary bypass but carries an operative recurrence rate of 57%. Successful cryoablation of a right atrial arrhythmia requires the reliable creation of transmural tissue necrosis. Heat transferred to the endocardium from normothermic circulating blood in the atrium or within the atrial wall may prevent full-thickness, lethal freezes. This study demonstrates that compression of myocardial tissue between an external cryoprobe and an endocardial template produces endocardial thermal isolation of the target area by displacing warm solutions from the endocardium. This is essential to achieve consistently lethal transmural freezes of -60 degrees C. Use of this technique may reduce the high operative recurrence rate of right atrial tachycardias treated with conventional cryoablation techniques.


Endometriosis causing colon obstruction in two postmenopausal women. Colonic endometriosis is an uncommon lesion usually found in premenopausal women. We describe two postmenopausal women with colonic endometriosis that resulted in colonic obstruction. One of the women was receiving estrogen-replacement therapy. Colonic endometriosis in postmenopausal women may become more common as the population ages and the use of long-term estrogen-replacement therapy becomes increasingly widespread.


[Isolation and purification of Brucella antigens synthesized by Escherichia coli K12 cells]. The homogeneous preparations of the brucella protein antigens were isolated from the hybrid producer strains Escherichia coli 6SE579 and 6SE800 by the cold osmotic shock technique and further purification on immunosorbents. The 18 + 38 and 38 kDa antigens were obtained. The antiserum specific to brucella 38 kDa antigen was obtained and used for isolation of the 18 kDa antigen from the producer strain 6SE579 synthesizing two brucella antigens. The immunosorbent developed on the basis of BrCn-agarose conjugated with antibodies from the serum has permitted isolation of 18 kDa protein antigen preparation. Thus, the combined technique of cold osmotic shock and affinity chromatography on immunosorbents permits one to isolate highly purified individual antigens of brucella from Escherichia coli K12 producer cells.


[Plasmid heterogeneity in populations of Yersinia pestis strains]. Yersinia pestis strains with the typical plasmid patterns were shown to have the heterogenic populations. Heterogeneity is increased by cultivation passages in artificial nutrient media and is manifested in plasmid elimination within several clones, plasmid integration into the chromosome, appearance of auxiliary plasmids or the ones with increased molecular masses. Passages of strains in experimental animals result in populations homogeneity with the typical plasmid patterns within all clones tested. The clones having changed the plasmid content and selected from heterogenic populations pertain their properties when cultivated in nutrient media and passaged in experimental animals.


[Mu-induced deletions and mutations of Erwinia carotovora chromosomes, including resident prophages E105 and 59]. The plasmid RP4::Mu cts62 in stably inherited by Erwinia carotovora 268 strain. Under the conditions of thermoinduction bacteriophage Mu is segregated and completely eliminated more intensively than in Escherichia coli cells. At thermoinduction the transposition of bacteriophage Mu cts62 into different chromosomal sites takes place, causing the induction of chlorate resistant and auxotrophic mutants with the frequency of 10(-4). Two clones deficient in production of 2 of the 4 resident prophages of Erwinia carotovora 268 strain were found among Mu-induced mutants. The deleted prophages are E105 and 59. DNA-DNA hybridization has revealed the complete and partial deletions of bacteriophage E105 with the level of L-asparaginase production in the cells remaining intact. The damage of the prophage 59 is probably caused by point mutations or short deletions.


Improvement of the exercise test after therapy in thyrotoxic periodic paralysis. The diagnosis of periodic paralysis (PP) can be aided by demonstrating a decrease in compound motor action potential (CMAP) amplitude after several minutes of exercise. We report a case of secondary hypokalemic PP due to thyrotoxicosis in which the decrease in the CMAP amplitude after exercise dramatically improved after treatment, when a euthyroid state was achieved. The exercise test is a useful electrophysiologic means of monitoring the neuromuscular status of patients with thyrotoxic periodic paralysis prior to, and after treatment of the thyrotoxicosis.


[Preparative isolation of basic structural proteins of the influenza virus]. The schemes for preparative electrophoretic isolation and purification of major proteins from influenza virus are described. The viral envelope protein, hemagglutinin, two of its subunits, internal M and NP proteins of influenza viruses A/FPV/Rostock (H7N1), A/PR/8/34 (H1N1) and X-31 (H3N2) were obtained in preparative amounts and characterized by amino acid and N-terminus analyses.


The spectrum of concentric macro EMG correlations. Part I. Normal subjects. Using a concentric macro electrode, both the concentric and macro action potentials of a motor unit were analyzed for duration, area, and amplitude. Eighty-six different motor units were analyzed from the tibialis anterior muscle in 10 normal subjects. The aim of this work was to compare concentric and macro action potential measurements of the same motor unit. The study revealed significant correlations between concentric and macro samples, with the concentric potential's area correlating better with the macro potential than its amplitude. This shows that the 10 to 15 muscle fibers studied by the concentric electrode serve as a good sample of the motor unit as a whole. We briefly review the technique used in concentric macro EMG, as well as describe the methods used for collecting and comparing both concentric and macro action potentials.


The spectrum of concentric macro EMG correlations. Part II. Patients with diseases of muscle and nerve. In the second part of this study we investigate the correlations between the concentric and conmac action potentials in motor units of individuals with diseases of muscle and nerve. We studied 86 myopathic and 86 neurogenic motor units and compared their concentric and conmac action potentials. In the patients with myopathy, we found that the concentric motor unit action potential's (MUAP) area correlates strongly with the conmac potential, even better than in normals, while its amplitude correlates less. In the neurogenic group, we found that both the concentric MUAP's area and amplitude correlated very well with their conmac counterpart, more so than in normals. Thus, in pathology, as in normals, measuring the concentric MUAP's area in addition to its amplitude adds to the diagnostic sensitivity of motor unit potential measurements. These findings are discussed in light of the known dynamic and architectural motor unit changes which take place in the myopathic and neurogenic motor unit.


[Restriction analysis of Thiobacillus ferrooxidans DNA using pulsed field electrophoresis]. The DNA of Thiobacillus ferrooxidans digested by any of the five restriction endonucleases (DraI, EcoRI, Eco321, HindIII, XbaI) was studied by electrophoresis in the pulsating differently directed electric fields (PF). The influence of PF conditions on the sized row of the divided DNA fragments was studied. Only the XbaI restriction endonuclease was shown to cleave the Thiobacillus ferrooxidans DNA into a number of fragments permitting one to define the sizes of fragments and genome (no more than 2300 bp). The prospects of using the restriction analysis of Thiobacillus ferrooxidans wild type culture for improving its properties in obtaining heavy metals are discussed.


Effects of age, sex, and anthropometric factors on nerve conduction measures. Associations among measures of median, ulnar, and sural nerve conduction and age, skin temperature, sex, and anthropometric factors were evaluated in a population of 105 healthy, asymptomatic adults without occupational exposure to highly repetitive or forceful hand exertions. Height was negatively associated with sensory amplitude in all nerves tested (P less than 0.001), and positively associated with median and ulnar sensory distal latencies (P less than 0.01) and sural latency (P less than 0.001). Index finger circumference was negatively associated with median and ulnar sensory amplitudes (P less than 0.05). Sex, in isolation from highly correlated anthropometric factors such as height, was not found to be a significant predictor of median or ulnar nerve conduction measures. Equations using age, height, and finger circumference for prediction of normal values are presented. Failure to adjust normal nerve conduction values for these factors decreases the diagnostic specificity and sensitivity of the described measures, and may result in misclassification of individuals.


[Determination of the effectiveness of RNA cross-linking with protein induced by UV-radiation in potato X-virus particles]. The UV-irradiation was found to induce formation of the RNA-protein cross-links and intraviral RNA chain breaks in the particles of flexuous potato virus X (PVX). Using the technique developed previously for the rod-like tobacco mosaic virus (TMV), the quantum yields of RNA-protein cross-links and intraviral RNA polynucleotide chain breaks formation in the PVX were determined and found to be more or less close to those found for the intraviral TMV RNA.


Differential expression of muscular dystrophy in diaphragm versus hindlimb muscles of mdx mice. Contractile properties of diaphragm (DIA) from mdx and control mice were compared with those of hindlimb muscles [soleus (SOL) and extensor digitorum longus (EDL)] in vitro. Mice ranged in age from 2 weeks to 1.5 years. Muscles were directly stimulated and properties measured were: contraction time, half-relaxation time, active tension per unit area, fatigue index, and maximal velocity of shortening (Vmax). Active tension decreased significantly with age in mdx DIA but not in control DIA. SOL and EDL active tensions were less in mdx than control over the whole age range and did not decrease with age. Vmax was decreased in mdx DIA, but not in mdx SOL or EDL. These results demonstrate that DIA is more affected by muscular dystrophy than hindlimb muscles. Since many Duchenne patients exhibit respiratory distress, this differential expression of dystrophy in diaphragm, as compared to limb muscles, may have important clinical implications.


Nerve conduction studies in amyotrophic lateral sclerosis. Nerve conduction studies (NCS) are an integral part of the evaluation of amyotrophic lateral sclerosis (ALS) patients and are useful in distinguishing ALS from disorders that mimic it. The question often arises whether in the presence of severe atrophy and reduction of the compound muscle action potential amplitude, abnormal conduction velocity (CV), distal latency (DL), or F-wave latency (F) exceeds what can be expected from ALS alone. To determine the limits of abnormality in classic ALS, we prospectively evaluated NCS data from 61 patients who met a strict clinical definition of ALS. We related CV, DL, and F to distal evoked amplitude (AMP) in peroneal (n = 63 observations), median (n = 50), and ulnar (n = 52) nerves. In nerves with reduced AMP, CV rarely fell to less than 80% of the lower limit of normal, and DL and F rarely exceeded 1.25 times the upper limit of normal. Utilizing the entire data set and regression analyses, 95% confidence limits for expected values for CV, F, and DL as a function of AMP were calculated. These limits thus derived suggest criteria for NCS abnormalities in ALS and may be useful in differentiating ALS from other illnesses.


Mild ischemia causes severe pathological changes in experimental diabetic nerve. Nerve ischemia is considered one of etiological factors in the development of structural changes in peripheral nerves associated with diabetes mellitus. To assess the effect of mild ischemia on diabetic nerve, a subthreshold dose of polystyrene microspheres was injected intraarterially to occlude microvessels of the sciatic nerve and its branches in 20-week streptozotocin-induced diabetic and control rats. Diabetic sciatic and tibial nerves showed severe pathological change of myelinated fibers, whereas nondiabetic nerves were normal or had minor structural abnormalities. Morphometrical evaluation confirmed a greater frequency of abnormal myelinated fibers in diabetic nerves especially in central fascicular regions. The results indicate that diabetic nerve has an increased morphological susceptibility to nerve ischemia. Endoneurial hypoxia, which may result from hemorheological and vascular abnormalities, is likely to cause a lowered threshold to ischemic tolerance in diabetic nerve. This increased vulnerability to ischemia may render diabetic nerve unduly susceptible to hyperglycemia-induced systemic tissue abnormalities.


Neuromuscular responses of patients with multiple sclerosis. Muscle weakness, studied in 4 patients with multiple sclerosis (MS), was compared with values from normal subjects. Twitch occlusion showed that normal subjects could activate their muscles maximally, but patients rarely achieved greater than 60% activation. In both groups, motoneuron firing rates increased linearly with force. Consistent with the reduced level of activation, MCV firing rates in MS muscles rarely exceeded 17 Hz (compared with approximately 24 Hz for normals). However, for right and left muscles of one patient, mean maximum firing rates were 14.2 +/- 2 Hz and 8.0 +/- 2 Hz, but her muscles, could be activated to levels greater than 92% and 60%, respectively. This patient's ability to achieve higher than expected forces at low firing rates was probably due to her slow muscle contractile speeds, especially 1/2-relaxation time (75 to 115 ms, cf. approximately 60 ms for normals), and high twitch/tetanus ratio (0.4, cf. 0.2).


F waves and motor unit size.

F waves and motor unit size. M responses and twitch contractions were evoked in single motor units (MUs) of the first dorsal interosseus muscle by intramuscular microstimulation of motor axons. Two-hundred nine MUs were studied in 21 subjects. Thirty-five MUs (17%) showed F waves in addition to M responses. Twitch force was used to provide an indirect measure of MU size; additionally, twitch contraction time was measured. There was no select group of MUs generating F waves with regard to the above contraction parameters. However, four of five MUs with very high twitch forces, above 70 mN, generated F waves. We conclude that MUs of all sizes produce F waves with similar probability. Only few MUs with very strong twitch forces, i.e., very large MUs, may be more subject to F-wave production and may be involved in the generation of the so-called repeater F waves.


Oral candidosis: treatment with absorbable and non-absorbable antifungal agents in children. Oral candidosis in neonates and children is a common infection which occurs often during the first few months after birth, but occasionally also in older children with certain predisposing factors. In neonates, oral candidosis is usually benign, although the symptoms of such an acute infection can be disturbing to both the patient and the parents. In older children developing oral candidosis, specific predisposing factors may be present (e.g. immunodeficiency, chemotherapy, etc.). In such cases, the infection may constitute a source for further dissemination, leading to occasionally fatal Candida sepsis or to widespread chronic mucocutaneous candidosis. Treatment modalities to date include drugs with limited or no absorption from the gastrointestinal tract (e.g. nystatin and miconazole) and agents that are absorbed, combining local effect with systemic therapy (e.g. clotrimazole, ketoconazole, itraconazole and fluconazole). Overall, it appears that treatment of neonatal oral candidosis should be performed with non-absorbable drugs, while the systemically active agents should be used primarily if a risk of dissemination exists or if widespread disease is present. In general, side-effects and toxicity are not major causes of concern with non-absorbed or absorbed antifungals in children with oral candidosis, since treatment is usually of relatively short duration. When the systemically active agents are used in premature infants with sub-optimal liver function, the risk of drug-induced liver toxicity may be increased.


Melanized and non-melanized multicellular form mutants of Wangiella dermatitidis in mice: mortality and histopathology studies. One melanized (Mc3) and one non-melanized (Mc3W) multicellular form mutant of W. dermatitidis were compared with parental wild type in NYLAR mice. Each mutant grows as multicellular (muriform-like) forms in vitro at 37 degrees C and as yeasts at less than or equal to 30 degrees C. Yeast cells of all three strains were injected intravenously at concentrations of 1 x 10(4), 1 x 10(6), 1 x 10(7), 3 x 10(7) and 1 x 10(8) cells/mouse in groups of 10 mice. There was no virulence difference between wild type and Mc3, with 100% mortality obtained with each strain at greater than or equal to 1 x 10(7) cells/mouse. In contrast, Mc3W was less virulent, with mortality being obtained only at 1 x 10(8) cells/mouse. Histopathological study of brains, lungs, livers and spleens of moribund mice revealed that both Mc3 and Mc3W persisted in tissue as muriform cells, and in some cases as yeast, pseudohyphal and hyphal forms. There was no major difference between Mc3 and Mc3W in terms of histopathological response. These data support the association between melanin and virulence in W. dermatitidis and provide a model for the study of muriform cells in vivo.


Fungal infections following heart transplantation. Following heart transplantation (HTx), patients often suffer from mycoses due to the necessary immunosuppressive treatment to prevent rejection episodes. Oropharyngeal Candida infections which mostly occur after HTx under high-dose immunosuppressive therapy can be avoided and treated successfully by prophylactic medication to be started immediately after transplantation, either by using azoles (e.g. fluconazole) or amphotericin B suspension. Contrary to this, invasive aspergillosis, beginning in the upper respiratory tract and the lung and mostly followed by hematogenous dissemination into various organs, is always a serious disease with high mortality. To avoid this infection, specimens from the respiratory tract, serum and urine should be examined mycologically prior to HTx. After HTx, apart from prophylactic avoidance of exposure to airborne fungal spores, close mycological control is mandatory to detect colonizations by aspergilli early. Timely administration of amphotericin B and 5-flucytosine, i.e. as soon as invasive growth is suspected, enables curative treatment of the often lethal course of this disease, even under immunosuppressive therapy.


Tissue response in sporotrichosis: light and electron microscopy studies. On the basis of electron microscopy examination of human tissue affected by sporotrichosis, we have proposed a classification, at the light microscopy level, of fungal cells in tissue. Light and electron microscopy observations clarified the following five points: (1) in sporotrichosis lesions in man, the fungal cells are frequently phagocytized by polymorphonuclear leucocytes (PMNs); (2) phagocytosis of phagocytes by other phagocytes was common, and giant cells phagocytized both fungal cells and PMNs; (3) fungal cells in the tissues of lesions were thought to be highly viable, and their budding was frequently observed within macrophages and giant cells; (4) it was highly probable that PMNs participated in asteroid body formation; (5) few free fungal cells were present in the tissues. We believe that the classification of fungal cells in sporotrichosis tissue into the five categories below is useful for correctly understanding the pathological condition in a sporotrichosis lesion: (1) fungal cells in PMNs, (2) fungal cells in PMNs within macrophages, (3) fungal cells in macrophages, (4) fungal cells in giant cells, and (5) free fungal cells.


Symmetrical deforming cutaneous sporotrichosis of long duration. A symmetrical deforming cutaneous sporotrichosis with verrucous lesions on both hands and of long clinical duration is reported. The difficulties in making an etiological diagnosis are considered.


The use of viral culture and p24 antigen testing to diagnose human immunodeficiency virus infection in neonates. The HIV Infection in Newborns French Collaborative Study Group. Early diagnosis of human immunodeficiency virus (HIV) infection in infants born to infected mothers is important for the infants' medical care, but the presence of maternal antibodies makes serologic tests uninformative. In a cohort study of 181 infants born to HIV-infected mothers, we assessed the diagnostic value of HIV viral culture and testing for the presence of p24 antigen. The infants were tested at birth, again during the first 3 months, then followed and tested at the age of at least 18 months. Of the 181 infants, 3 died of HIV infection and 37 were seropositive after the age of 18 months. Viral cultures at birth were positive in 19 of the 40 infected infants and in none of the uninfected infants, yielding a sensitivity of 48 percent (95 percent confidence interval, 32 to 63 percent) and a specificity of 100 percent (95 percent confidence interval, 97 to 100 percent). By the age of three months, 30 of the 40 infants (75 percent) had positive cultures; again, there were no false positive results among the infants who were tested a second time, of the 141 who remained uninfected. The sensitivity of testing for p24 antigen at birth was only 18 percent, with a specificity of 100 percent. The presence of p24 antigen at birth was associated with the development of early and severe HIV-related disease (P less than 0.04). Viral culture at birth can correctly identify about half of newborns with HIV infection. The fact that this usually sensitive technique fails to identify about half the ultimately infected neonates suggests that vertical transmission of HIV may occur late in pregnancy or during delivery.


Induction of immune responses in patients with B-cell lymphoma against the surface-immunoglobulin idiotype expressed by their tumors. The idiotypic determinants of the surface immunoglobulin of a B-cell lymphoma can serve as a clonal tumor-specific marker, which may have implications for immunotherapy. We sought to determine whether idiotype-specific immune responses against this autologous antigen could be induced in patients with B-cell lymphoma. Nine patients were selected who had minimal residual disease or a complete remission after chemotherapy. Each received a series of subcutaneous injections of the immunoglobulin derived from his or her tumor cells (immunoglobulin-idiotype protein), which had been conjugated to a protein carrier and mixed with an immunologic adjuvant. In seven of the nine patients the injections induced sustained idiotype-specific immunologic responses of the humoral type (two patients), the cell-mediated type (four patients), or both (one patient). The use of an adjuvant was essential for these immune responses. The induced antibodies bound specifically to autologous immunoglobulin idiotype, inhibited the binding of murine monoclonal antiidiotype antibodies, and bound autologous tumor cells. Cell-mediated responses were demonstrated by the specific proliferation of immune peripheral-blood mononuclear cells to the soluble immunoglobulin-idiotype protein in vitro. The tumors of both of the patients with measurable disease regressed completely. Toxicity associated with the vaccine was minimal and consisted only of mild reactions at the site of intramuscular injection. These results demonstrate that autologous immunoglobulin idiotype can be formulated into an immunogenic, tumor-specific antigen in humans with B-cell lymphoma, and they provide the background for large-scale trials of active specific immunotherapy of this disease.


Virulence of Candida albicans mutants.

Virulence of Candida albicans mutants. Mutant strains of the fungal pathogen Candida albicans blocked in pyrimidine transport and salvage metabolism were tested for virulence in various animal models. The growth rate, germination and proteolytic enzyme production did not correlate with the virulence of the strains. However, a defect in the uridine transport system significantly decreased virulence in murine candidosis, although it had no effect in vaginal candidosis or in a Candida cyst model. It remains unclear whether this is due to the differing host defence mechanisms involved in systemic and superficial mycoses, or to the different requirements of the fungal systems for adherence and tissue invasion in the two types of infection.


The relation between experience and outcome in heart transplantation. Current policies related to organ transplantation in the United States are designed to ensure that centers and physicians with experience in transplantation perform these procedures. It is essential to confirm the validity of such policies, since they may limit access to transplantation services. To determine the relation between experience with heart transplantation and mortality after the procedure, we merged data from the registry of the International Society for Heart and Lung Transplantation with data from a survey that provided additional information about patients and transplantation centers. Our study included 1123 patients who received a heart transplant at one of 56 hospitals in the United States from 1984 through 1986. We used univariate and bivariate techniques, as well as logistic regression, to analyze our data. We observed an institutional learning curve for heart transplantation. Patients who received one of a center's first five transplants had higher mortality rates than patients who received a subsequent transplant (20 percent vs. 12 percent; P = 0.002; relative risk = 2.2; 95 percent confidence interval, 1.6 to 3.4). In addition, we found a correlation between the training of key personnel on the transplantation team and mortality at new transplantation centers. For example, new centers staffed by cardiologists with previous training in heart transplantation had lower mortality rates among heart-transplant recipients than centers without experienced cardiologists (7 percent vs. 16 percent; P = 0.001; relative risk = 2.7; 95 percent confidence interval, 1.3 to 5.9). By contrast, the previous training of the surgeons who performed transplantations was not related to the mortality rate associated with the procedure. Experience with heart transplantation is associated with a better outcome for patients after that procedure. Opportunities exist to refine transplantation policies on the basis of the experience of a center and its transplantation team and to develop similar policies for other forms of organ transplantation.


Candidaemia: a 10-year study in an Indian teaching hospital. Retrospective evaluation of candidaemia patients was performed in an Indian teaching hospital over a 10-year period. The incidence of patients with candidaemia increased eleven-fold in the second half of the study period (55 patients) compared with the first half (5 patients). Haematological malignancies (11 patients), neonatal septicaemia (9), cardiac abnormalities and cardiac surgery (9) were the commonest underlying diseases in these patients. Candida albicans (50%), C. guilliermondii (17%), C. tropicalis (15%) and C. parapsilosis (8%) were the most common fungal pathogens isolated from blood culture. Therapy with two or more antibiotics (92%), corticosteroid administration (25%), intravascular catheter use for over 24 h (78%) and neutropenia (48%) were the accountable predisposing factors. Prolonged hospitalization (mean average 22.2 days as compared with 11.2 days in other patients) was an added risk factor in these patients.


Susceptibility to ketoconazole of Candida albicans strains from sequentially followed HIV-1 patients with recurrent oral candidosis. The MIC values of the antifungal drug ketoconazole were evaluated on 66 Candida albicans strains. These strains were isolated from 26 HIV-1 infected patients with oral recurrent candidosis. Each episode of oral candidosis observed in these patients was orally treated with ketoconazole (200 mg/day) until the clinical disappearance of the lesions. The most frequent MIC values were 20 micrograms/ml and 10 micrograms/ml, observed in 37 and 19 isolates respectively. Only strains from five patients showed changes in their susceptibility to ketoconazole. This fact could indicate that a different strain causes the subsequent reappearance of the oral lesions, rather than the drug selecting resistant fungal strains. Our results stress the role of host characteristics in the occurrence of candidal infections, pointing to the progressing failure of the immunological response as the most important factor responsible for the recurrence of oral candidosis during HIV-1 infection.


A double-blind, placebo-controlled multicenter study of tacrine for Alzheimer's disease. The Tacrine Collaborative Study Group. In Alzheimer's disease, there is a marked decline in the function of cholinergic neurons in the brain. However, studies of treatment with cholinesterase inhibitors have produced conflicting results. We conducted a multicenter trial to evaluate whether the cholinesterase inhibitor tacrine (1,2,3,4-tetrahydro-9-acridinamine monohydrochloride monohydrate) could improve cognition in patients with Alzheimer's disease. Of 632 eligible patients with probable Alzheimer's disease, 215 improved while receiving tacrine during a preliminary crossover phase to determine responsiveness and the best dose. The 215 patients were randomly assigned to receive either placebo or their best dose of tacrine (10 or 20 mg four times a day) in a six-week, double-blind trial. The primary measures of efficacy were the cognitive subscale of the Alzheimer's Disease Assessment Scale and the Clinical Global Impression of Change scale; the secondary measures included the Mini-Mental State Examination and the assessment of the activities of daily living. At the end of the six-week trial, the patients receiving tacrine had a mean adjusted cognitive-subscale score of 30.3 (Alzheimer's Disease Assessment Scale) as compared with 32.7 in patients receiving placebo. This represents a smaller decline (by 2.4 points) in cognitive performance in the tacrine group (P < 0.001). There were no differences between the groups in their global-rating scores. The tacrine group had a significantly smaller decline in the activities of daily living. The results of the Mini-Mental State Examination favored tacrine, but the differences were small and not statistically significant (a score of 16.0 with tacrine vs. 15.3 with placebo; P = 0.08). Gastrointestinal symptoms, elevation of aminotransferase levels, and headache were the most frequent side effects; all could be reversed by reducing the dose or discontinuing treatment. In this short-term study in patients with Alzheimer's disease who were selected for apparent responsiveness to tacrine, treatment with tacrine resulted in a statistically significant reduction in the decline of cognitive function, although this reduction was not large enough to be detected by the study physicians' global assessments of the patients.


Cardiac structure and function in children with human immunodeficiency virus infection treated with zidovudine. Abnormalities of cardiac structure and function are common in children infected with the human immunodeficiency virus (HIV). It is unclear, however, whether these abnormalities are attributable to the disease itself, associated infections, or possible cardiotoxic effects of the most commonly used treatment, zidovudine. We performed echocardiography in 24 children with symptomatic HIV infection immediately before they started zidovudine therapy and a mean of 1.32 years after therapy began. Sixteen of these children were also studied a mean of 1.26 years before starting zidovudine treatment. Comparison groups included 27 age-matched children with symptomatic HIV infection who had not received zidovudine and 191 normal children. As compared with the normal children, the children treated with zidovudine had progressive left ventricular dilatation and an increase in ventricular-wall stress at end-systole (a measure of ventricular afterload); dilatation and stress were significantly elevated both before and during zidovudine treatment. The ratio of ventricular thickness to internal dimension was below normal before zidovudine treatment began (P < 0.001). After treatment with zidovudine, however, overall left ventricular mass was increased (P = 0.02), as was peak wall stress (a stimulus to ventricular hypertrophy) (P = 0.01). Ventricular contractility remained normal, but fractional shortening of the left ventricle was decreased (P = 0.004). No statistically significant differences were detected at follow-up in any of these measurements between HIV-infected children treated with zidovudine and those not so treated. Progressive left ventricular dilatation occurred in children with symptomatic HIV infection. Compensatory hypertrophy also occurred but was inadequate to maintain peak systolic wall stress within the normal range. The progressive elevation of ventricular afterload due to dilatation resulted in depressed ventricular performance, but intrinsic ventricular contractility remained normal. Zidovudine did not appear to worsen or ameliorate these cardiac changes.


Predictors of long-term outcome after percutaneous balloon mitral valvuloplasty. Percutaneous balloon mitral valvuloplasty is known to produce short-term hemodynamic and symptomatic improvement in many patients with mitral stenosis. Comprehensive assessment of the clinical usefulness of balloon valvuloplasty requires evaluation of patients' long-term outcomes. We performed balloon mitral valvuloplasty in 146 patients between October 1, 1985, and October 1, 1991. Base-line demographic, clinical, echocardiographic, and hemodynamic variables were evaluated in order to identify predictors of long-term event-free survival. Balloon mitral valvuloplasty was completed successfully in 136 (93 percent) of the patients in whom the procedure was attempted; it resulted in an increase in the mean (+/- SD) mitral-valve area from 1.0 +/- 0.4 to 2.1 +/- 0.9 cm2 and a decrease in the mean transmitral pressure gradient from 14 +/- 5 to 6 +/- 3 mm Hg (P < 0.001 for both comparisons). The estimated overall five-year survival rate was 76 +/- 5 percent, and the estimated five-year event-free survival rate (the percentage of patients without mitral-valve replacement, repeat valvuloplasty, or death from cardiac causes) was 51 +/- 6 percent. According to multivariate Cox proportional-hazards analysis, the independent predictors of longer event-free survival were a lower mitral-valve echocardiographic score (a measure of mitral-valve deformity; range, 0 for a normal valve to 16 for a seriously deformed valve; P < 0.001), lower left ventricular end-diastolic pressure (P = 0.001), and a lower New York Heart Association (NYHA) functional class (P = 0.04). Patients with no risk factors for early restenosis or only one risk factor (echocardiographic score > 8, left ventricular end-diastolic pressure > 10 mm Hg, or NYHA functional class IV) had a predicted five-year event-free survival rate of 60 to 84 percent, whereas patients with two or three risk factors had a predicted five-year event-free survival rate of only 13 to 41 percent. Balloon mitral valvuloplasty as a treatment for selected patients with mitral stenosis has good long-term results. The long-term outcome after this procedure can be predicted on the basis of patients' base-line characteristics.


Interferon alfa combined with cytotoxic chemotherapy for patients with non-Hodgkin's lymphoma. Interferon alfa has been found to be effective as an antitumor agent (with a response rate of 30 percent) in patients with low-grade non-Hodgkin's lymphoma, but its effectiveness in those with intermediate-grade non-Hodgkin's lymphoma has been less adequately tested. In a prospective randomized study we evaluated the effectiveness of adding interferon alfa to cytotoxic chemotherapy in patients with clinically aggressive, low-grade non-Hodgkin's lymphoma and certain histologic variants of intermediate-grade non-Hodgkin's lymphoma, not including diffuse histiocytic lymphoma. The patients were randomly assigned to a regimen of cyclophosphamide, vincristine, prednisone, and doxorubicin or to this regimen combined with recombinant interferon alfa. Treatment was administered every four weeks, for 8 to 10 cycles. The two regimens produced comparable objective responses, but the regimen including interferon had a greater effect in prolonging the time to treatment failure (P < 0.001) and the duration of complete response (P = 0.03). Interferon alfa also had a greater effect on overall survival (P = 0.014) when the results were adjusted for important covariates. Interferon alfa, when added to a four-drug doxorubicin-based chemotherapy regimen, is an effective antitumor agent in patients with clinically aggressive low-grade or intermediate-grade non-Hodgkin's lymphoma.


Long-term morbidity and mortality of overweight adolescents. A follow-up of the Harvard Growth Study of 1922 to 1935. Overweight in adults is associated with increased morbidity and mortality. In contrast, the long-term effect of overweight in adolescence on morbidity and mortality is not known. We studied the relation between overweight and morbidity and mortality in 508 lean or overweight adolescents 13 to 18 years old who participated in the Harvard Growth Study of 1922 to 1935. Overweight adolescents were defined as those with a body-mass index that on two occasions was greater than the 75th percentile in subjects of the same age and sex in a large national survey. Lean adolescents were defined as those with a body-mass index between the 25th and 50th percentiles. Subjects who were still alive were interviewed in 1988 to obtain information about their medical history, weight, functional capacity, and other risk factors. For those who had died, information on the cause of death was obtained from death certificates. Overweight in adolescent subjects was associated with an increased risk of mortality from all causes and disease-specific mortality among men, but not among women. The relative risks among men were 1.8 (95 percent confidence interval, 1.2 to 2.7; P = 0.004) for mortality from all causes and 2.3 (95 percent confidence interval, 1.4 to 4.1; P = 0.002) for mortality from coronary heart disease. The risk of morbidity from coronary heart disease and atherosclerosis was increased among men and women who had been overweight in adolescence. The risk of colorectal cancer and gout was increased among men and the risk of arthritis was increased among women who had been overweight in adolescence. Overweight in adolescence was a more powerful predictor of these risks than overweight in adulthood. Overweight in adolescence predicted a broad range of adverse health effects that were independent of adult weight after 55 years of follow-up.


The psychological consequences of predictive testing for Huntington's disease. Canadian Collaborative Study of Predictive Testing. Advances in molecular genetics have led to the development of tests that can predict the risk of inheriting the genes for several adult-onset diseases. However, the psychological consequences of such testing are not well understood. The 135 participants in the Canadian program of genetic testing to predict the risk of Huntington's disease were followed prospectively in three groups according to their test results: the increased-risk group (37 participants), the decreased-risk group (58 participants), and the group with no change in risk (the no-change group) (40 participants). All the participants received counseling before and after testing. Standard measures of psychological distress (the General Severity Index of the Symptom Check List 90-R), depression (the Beck Depression Inventory), and well-being (the General Well-Being Scale) were administered before genetic testing and again at intervals of 7 to 10 days, 6 months, and 12 months after the participants received their test results. At each follow-up assessment, the decreased-risk group had lower scores for distress than before testing (P < 0.001). The increased-risk group showed no significant change from base line on any follow-up measure, but over the year of study there were small linear declines (P < 0.023) for distress and depression. The no-change group had scores lower than at base line on the index of general well-being at each follow-up (P < or = 0.045). At the 12-month follow-up, both the increased-risk group and the decreased-risk group had lower scores for depression and higher scores for well-being than the no-change group (P < or = 0.049). Predictive testing for Huntington's disease has potential benefits for the psychological health of persons who receive results that indicate either an increase or a decrease in the risk of inheriting the gene for the disease.


Warfarin in the prevention of stroke associated with nonrheumatic atrial fibrillation. Veterans Affairs Stroke Prevention in Nonrheumatic Atrial Fibrillation Investigators. Nonrheumatic atrial fibrillation is common among the elderly and is associated with an increased risk of stroke. We investigated whether anticoagulation with warfarin would reduce this risk. We conducted a randomized, double-blind, placebo-controlled study to evaluate low-intensity anticoagulation with warfarin (prothrombin-time ratio, 1.2 to 1.5) in 571 men with chronic nonrheumatic atrial fibrillation; 525 patients had not previously had a cerebral infarction, whereas 46 patients had previously had such an event. The primary end point was cerebral infarction; secondary end points were cerebral hemorrhage and death. Among the patients with no history of stroke, cerebral infarction occurred in 19 of the 265 patients in the placebo group during an average follow-up of 1.7 years (4.3 percent per year) and in 4 of the 260 patients in the warfarin group during an average follow-up of 1.8 years (0.9 percent per year). The reduction in risk with warfarin therapy was 0.79 (95 percent confidence interval, 0.52 to 0.90; P = 0.001). The annual event rate among the 228 patients over 70 years of age was 4.8 percent in the placebo group and 0.9 percent in the warfarin group (risk reduction, 0.79; P = 0.02). The only cerebral hemorrhage occurred in a 73-year-old patient in the warfarin group. Other major hemorrhages, all gastrointestinal, occurred in 10 patients: 4 in the placebo group, for a rate of 0.9 percent per year, and 6 in the warfarin group, for a rate of 1.3 percent per year. There were 37 deaths that were not preceded by a cerebral end point--22 in the placebo group and 15 in the warfarin group (risk reduction, 0.31; P = 0.19). Cerebral infarction was more common among patients with a history of cerebral infarction (9.3 percent per year in the placebo group and 6.1 percent per year in the warfarin group) than among those without such a history. Low-intensity anticoagulation with warfarin prevented cerebral infarction in patients with nonrheumatic atrial fibrillation without producing an excess risk of major hemorrhage. This benefit extended to patients over 70 years of age.


Comparison of insulin regimens in patients with non-insulin-dependent diabetes mellitus. Insulin is widely used to improve metabolic control in patients with non-insulin-dependent diabetes mellitus (NIDDM), but there is no consensus about the optimal regimen of insulin treatment. We treated 153 patients with NIDDM for three months with five regimens: (1) oral hypoglycemic drug therapy plus NPH insulin given at 7 a.m. (the morning-NPH group), (2) oral hypoglycemic drug therapy plus NPH insulin given at 9 p.m. (the evening-NPH group), (3) NPH and regular insulin (ratio, 70 units to 30 units) given before breakfast and dinner (the two-insulin-injection group), (4) NPH insulin at 9 p.m. and regular insulin before meals (the multiple-insulin-injection group), and (5) continued oral hypoglycemic drug therapy (the control group). The mean (+/- SE) value for glycosylated hemoglobin decreased similarly in all four insulin-treatment groups (1.7 +/- 0.3, 1.9 +/- 0.2, 1.8 +/- 0.3, and 1.6 +/- 0.3 percent, respectively). The decrease was significantly greater in these four groups than in the control group (0.5 +/- 0.2 percent; P < 0.001 vs. all insulin-treated groups). Weight gain was significantly less (1.2 +/- 0.5 kg) in the evening-NPH group than in the other insulin-treatment groups (2.2 +/- 0.5 kg in the morning-NPH group, 1.8 +/- 0.5 kg in the two-insulin-injection group, and 2.9 +/- 0.5 kg in the multiple-injection group; P < 0.05). In addition, the increment in the mean diurnal serum free insulin concentration was 50 to 65 percent smaller in the evening-NPH group than in the other insulin-treatment groups. Subjective well-being improved significantly more in the insulin-treatment groups than in the control group (P < 0.001). In patients with NIDDM who are receiving oral hypoglycemic drug therapy, the addition of NPH insulin in the evening improves glycemic control in a manner similar to combination therapy with NPH insulin in the morning, a two-insulin-injection regimen, or a multiple-insulin-injection regimen, but induces less weight gain and hyperinsulinemia. The data thus suggest that patients with NIDDM do not benefit from multiple insulin injections and that nocturnal insulin administration appears preferable to daytime administration.


Effect of iron chelation therapy on recovery from deep coma in children with cerebral malaria. Cerebral malaria is a severe complication of Plasmodium falciparum infection in children, with a mortality rate of 15 to 50 percent despite antimalarial therapy. To determine whether combining iron chelation with quinine therapy speeds the recovery of consciousness, we conducted a randomized, double-blind, placebo-controlled trial of the iron chelator deferoxamine in 83 Zambian children with cerebral malaria. To be enrolled, patients had to be less than six years old, have P. falciparum parasitemia, have normal cerebrospinal fluid without evidence of bacterial infection, and be in a coma from which they could not be aroused. Deferoxamine (100 mg per kilogram of body weight per day, infused intravenously for 72 hours) or placebo was added to standard therapy with quinine and sulfadoxine-pyrimethamine. The time to the recovery of full consciousness, time to parasite clearance, and mortality were examined with Cox proportional-hazards regression analysis. The rate of recovery of full consciousness among the 42 patients given deferoxamine was 1.3 times that among the 41 given placebo (95 percent confidence interval, 0.7 to 2.3); the median time to recovery was 20.2 hours in the deferoxamine group and 43.1 hours in the placebo group (P = 0.38). Among 50 patients with deep coma, the rate of recovery of full consciousness was increased 2.2-fold with deferoxamine (95 percent confidence interval, 1.1 to 4.7), decreasing the median recovery time from 68.2 to 24.1 hours (P = 0.03). Among 69 patients for whom data on parasite clearance were available, the rate of clearance with deferoxamine was 2.0 times that with placebo (95 percent confidence interval, 1.2 to 3.6). Among all 83 patients, mortality was 17 percent in the deferoxamine group and 22 percent in the placebo group (P = 0.52). Iron chelation therapy may hasten the clearance of parasitemia and enhance recovery from deep coma in cerebral malaria.


Acenocoumarol and heparin compared with acenocoumarol alone in the initial treatment of proximal-vein thrombosis. In most countries, heparin is used in the initial treatment of patients with deep-vein thrombosis. Well-designed studies establishing the efficacy of heparin therapy are lacking, however. Treatment with acenocoumarol alone, according to the hypothesis that high dosages of oral anticoagulants obviate the need for heparin, is considered an effective alternative in some countries. In a randomized, double-blind study we compared the efficacy and safety of continuous intravenous heparin plus acenocoumarol with the efficacy and safety of acenocoumarol alone in the initial treatment of outpatients with proximal-vein thrombosis. The principal study end point was a confirmed symptomatic extension or recurrence of venous thromboembolism during six months of follow-up. In addition, we assessed asymptomatic extension or pulmonary embolism by repeating venography and lung scanning after the first week of treatment. The incidence of major bleeding was determined during three months of follow-up. The study was terminated early by the Data Safety and Monitoring Committee because of an excess of symptomatic events in the group that received acenocoumarol alone (in 12 of 60 patients [20 percent], as compared with 4 of 60 patients [6.7 percent] in the combined-therapy group by intention-to-treat analysis; P = 0.058). Asymptomatic extension of venous thrombosis was observed in 39.6 percent of the patients in the acenocoumarol group and in 8.2 percent of patients treated with heparin plus acenocoumarol (P < 0.001). Major bleeding complications were infrequent and comparable in the two groups. Patients with proximal-vein thrombosis require initial treatment with full-dose heparin, which can safely be combined with acenocoumarol therapy.


Consequences of physicians' ownership of health care facilities--joint ventures in radiation therapy. Physicians are increasingly the owners of health care facilities to which they refer patients for services but at which they do not practice. We studied such ownership arrangements, known as "joint ventures," in the field of radiation therapy, examining their effects on access, use of services, costs, and quality. Because 44 percent of free-standing facilities providing radiation therapy in Florida in 1989 were joint ventures, as compared with 7 percent elsewhere (95 percent confidence interval, 3 to 10 percent), we compared data for Florida with comparable data for the remainder of the United States. We also compared radiation-therapy facilities in Florida that were established as joint ventures with those that were not. Since most data were derived from entire populations rather than from samples, any differences found were of necessity statistically significant. No joint-venture facilities providing radiation therapy were located in inner-city neighborhoods or rural areas, but 11 percent of other free-standing facilities and hospital-based facilities were located in such areas. Among free-standing facilities, joint ventures received 39 percent of their revenues from patients with well-paying insurance coverage, as compared with 31 percent for facilities that were not joint ventures (P < 0.01). The frequency and costs of radiation-therapy treatments at free-standing centers were 40 to 60 percent higher in Florida than in the rest of the United States; there was no below-average use of radiation therapy at hospitals or higher cancer rates that explained the higher rates of use or higher costs in Florida. Radiation physicists at joint-venture facilities (the principal personnel involved in quality control other than physicians) spent 18 percent less time with each patient over the course of treatment than did their counterparts at free-standing facilities that were not joint ventures (P < 0.05). Mortality among patients with cancer in Florida was not lower than the U.S. average, even though joint ventures are much more common in that state. Joint ventures in radiation therapy appear to have adverse effects on patients' access to care. They also appear to increase the use of services and costs substantially. Some indicators show that joint ventures cause either no improvement in quality or a decline. Our results add to the evidence indicating that physicians' self-referral generally has negative consequences. We recommend legislation to ban ownership of joint ventures by referring physicians. Such legislation needs to be carefully designed in order to achieve its objectives and forestall new, financially abusive arrangements.


Increased costs and rates of use in the California workers' compensation system as a result of self-referral by physicians. There is widespread concern that ownership by physicians of testing or treatment facilities to which they refer patients leads to overuse of such facilities. We determined the patterns of use of three services--physical therapy, psychiatric evaluation, and magnetic resonance imaging (MRI)--among physicians treating patients whose care was covered under workers' compensation. We then compared the rates of use among physicians who referred patients to facilities of which they were owners (self-referral group) with the rates among physicians who referred patients to independent facilities (independent-referral group). We used a large data base to analyze claims under workers' compensation in California from October 1, 1990, through June 30, 1991, to determine the frequency and cost of these three selected services and determined whether the referring physicians were practicing self-referral or independent referral. We evaluated the cost per case for all three services, measured the frequency with which physical therapy was initiated, and evaluated the medical appropriateness of MRI. We found that physical therapy was initiated 2.3 times more often by the physicians in the self-referral group (68 percent) than by those in the independent-referral group (30 percent; P < 0.01). The mean cost per case for physical therapy was significantly lower in the self-referral group ($404 +/- 102) than in the independent-referral group ($440 +/- 167; P < 0.01). The mean cost of psychiatric evaluation services was significantly higher in the self-referral group than in the independent-referral group (psychometric testing, $1,165 +/- 728 vs. $870 +/- 482; P < 0.01, psychiatric evaluation reports, $2,056 +/- 1,063 vs. $1,680 +/- 578; P < 0.01). The total cost per case of psychiatric evaluation services was 26.3 percent higher in the self-referral group ($3,222 +/- 1,451) than in the independent-referral group ($2,550 +/- 742; P < 0.01). Of all the MRI scans requested by the self-referring physicians, 38 percent were found to be medically inappropriate, as compared with 28 percent of those requested by physicians in the independent-referral group (P < 0.05). There was no significant difference in the cost per case between the two groups. This study demonstrates that self-referral increases the cost of medical care covered by workers' compensation for each of the three types of service studied.


In vitro activity of cloconazole, sulconazole, butoconazole, isoconazole, fenticonazole, and five other antifungal agents against clinical isolates of Candida albicans and Candida spp. The in vitro activity of several new imidazoles, cloconazole, sulconazole, butoconazole, isoconazole and fenticonazole, were compared with those of amphothericin B, flucytosine, and three azoles: econazole, miconazole and ketoconazole against isolates of pathogenic Candida. A total of 186 clinical isolates of 10 species of the genus Candida and two culture collection strains were tested by an agar-dilution technique. Isoconazole was the most active azole, followed by butoconazole sulconazole. Differences between some of the species in their susceptibility to the antifungal agents were noted. Sulconazole and cloconazole had the highest activity in vitro against 106 isolates of C. albicans. Butoconazole and isoconazole were also very active against isolates of C. albicans, and were the most active azole compounds against 80 isolates of Candida spp.


Use of a colorimetric system to detect enzymes expressed by germinating conidia of entomopathogenic fungi. An apiZYM system, with 19 substrates, was used to detect enzymes expressed by germinating conidia of Nomuraea rileyi (5 isolates), Nomuraea atypicola, Nomuraea anemonoides, Beauveria bassiana and Metarhizium anisopliae. Similar enzyme profiles were obtained for two of the N. rileyi isolates (Mississippi, Ecuador) regardless of whether culture medium (Sabouraud-maltose-yeast) or cuticle (from larvae of Trichoplusia ni, Heliothis zea or Heliothis virescens) were used as substrates. Centroid-clustering analysis revealed three distinct enzyme profiles.


Mushroom poisoning by Chlorophyllum molybdites in the Midwest United States. Cases and a review of the syndrome. The paper describes two incidents of poisoning by the mushroom Chlorophyllum molybdites and reviews the literature covering this organism, a common agent of mushroom poisoning in many countries and the most common cause of mushroom poisoning in North America. Both poisoning incidents occurred in adults and were associated with severe gastrointestinal symptoms including profuse diarrhea, vomiting and intestinal pain. In each case, hospitalization was required. An unusual aspect of one case was the development of signs and symptoms suggestive of muscarine poisoning. The review includes a description of the mushroom, the geographic distribution of cases, the signs and symptoms of poisoning and its treatment, the toxic principles, particularly susceptible populations, and the variations in response associated with cooking C. molybdites and with individual idiosyncrasies. For identification of C. molybdites, the reader is alerted to the inappropriateness of some books, including many written in Europe, and is warned of the occasional finding of sterile mushrooms that lack its characteristic green basidiospores. Spores, as allergens, are discussed and simple rules are given for eaters of wild mushrooms.


Pulmonary paracoccidioidomycosis in immunized mice. Paracoccidioidomycosis was induced in immunized (IM) and non-immunized (NI) mice. The histopathology, the number of fungi in the lungs, the cellular (footpad test--FPT and macrophage inhibition factor assay--MIF) and humoral (immunodiffusion test) immune response were investigated serially post-infection. In the IM mice, at days 1 and 3, there was intense and predominant macrophagic-lymphocytic alveolitis with loose granulomatous reaction; at day 30, inflammation was mild. In the NI group, up to day 3, the lesions were focal; later there was formation of extensive epithelioid granuloma. The number of fungi in IM mice were always smaller than those of NI group. Immunization alone induced positive FPT and MIF indices with low titer of antibody. After infection, there was a significant decrease of the FPT indices in the IM group, which we interpreted as desensitization due to trapping of sensitized lymphocytes in the lungs. In conclusion, (1) The lesional pattern of pulmonary paracoccidioidomycosis in IM mice was similar to that of a hypersensitivity pneumonitis. This reaction was probably effective in reducing the extension of the infection and decrease the number of fungi. (2) In this model, pulmonary resistance against P. brasiliensis seems to be related to local and systemic delayed-type hypersensitivity reaction.


Evaluation of the Pro-Lab ID ring system for the identification of medically important yeasts. We evaluated 151 coded isolates of medically important yeast species belonging to the genera Candida, Cryptococcus, Geotrichum, Rhodoturula, Saccharomyces and Torulopsis using the newly developed rapid Pro-Lab Identification Ring, PL 960 system (PLID-Ring). All isolates were concurrently identified by the API 20C and conventional procedures comprising macro- and micromorphology, assimilation and fermentation of various carbon and nitrogen compounds. The PLID-Ring system identified isolates of Candida albicans, C. kefyr, C. krusei, C. lusitaniae, C. parapsilosis, Rhodotorula rubra, and Torulopsis glabrata with 100% accuracy in 24 h. This system identified C guilliermondii and S. cerevisiae isolates with an accuracy of 90% and 86%, respectively, while those belonging to Cr. neoformans, T. candida (= C. famata), C. rugosa and C. tropicalis were identified with 38.4%, 50%, 12.5% and 50% accuracy, respectively. Three isolates of Cr. laurentii were not identified by the PLID-Ring system. The overall accuracy of the PLID-Ring system was 81.45% (123 of 151 isolates). However, the system does not include species such as Cr. laurentii in its data base. When these three Cr. laurentii isolates were excluded from the evaluation, the accuracy of the PLID-Ring system increased from 81.45% to 83.1%.


Effect of environmental factors on Fonsecaea pedrosoi morphogenesis with emphasis on sclerotic cells induced by propranolol. The influence of growth conditions, as well as of propranolol on Fonsecaea pedrosoi morphogenesis was established using the chemically defined media of Czapeck-Dox (CD) and Butterfield (BF). Mycelial growth of F. pedrosoi in both media was obtained at room temperature (25 degrees C) for 14 days, without shaking, whereas conidia formed at 37 degrees C, for 4 days, in shaken cultures and could be isolated free from the mycelium by filtration in gauze. At low pH (2.5-3.0), there appeared sclerotic cells attached to normal hyphae. When propranolol ws added to the CD medium moniliform hyphae were observed, whereas this drug in the BF medium induced formation of sclerotic cells. Ultrastructural examination revealed that the propranolol-induced sclerotic cells were very similar to those observed in infected tissues.


Forty four years of dermatophytes in a Chicago clinic (1944-1988). Data are presented on 39,270 cultures taken over a 44 year span (1944-1988) at the University of Chicago's Dermatology Clinic. In the mid 1940's Microsporum audouinii accounted for 60-80% of isolates. It gradually decreased over the next two decades and disappeared altogether in the 1970's. Trichophyton rubrum, rare in the 1940's accounted for over 60% of isolates in the mid-1960's only to be overtaken by T. tonsurans. This species, not isolated till the mid 1950's, became and remains the dominant dermatophyte at the present time. Both T. mentagrophytes and Epidermophyton floccosum increased in the 1970's and decreased later. Unusual circumstances resulted in clusters of T. verrucosum, T. terrestre, and T. schoenleinii isolates. Infections were associated with rural dairy workers, zoo handlers and immigrant families respectively. M. canis and M. gypseum were steady at a low rate throughout the entire period. Rare isolates included M. cookei, M. persicolor, M. racemosum, T. simii, T. soudanense, T. violaceum, and the soil keratinophile, Aphanoascus fulvescens.


Mycotic keratitis caused by Curvularia brachyspora (Boedjin). A report of the first case. Curvularia brachyspora has been identified for the first time as a cause of mycotic keratitis. Mycotic infections of the eye have assumed increasing importance in ophthalmology, resulting in a need for fungal identification and early specific treatment for the successful management of cases. A case of mycotic keratitis caused by C. brachyspora is described against the background of other Curvularia species causing mycoses.


Assessment of buprenorphine in a drug discrimination procedure in humans. These studies indicate that buprenorphine shares stimulus effects with other opioid drugs and that in overall profile of effects buprenorphine is more similar to hydromorphone than are the other opioid mixed agonist-antagonists tested-pentazocine, butorphanol, and nalbuphine. This characterization is supported by the behavioral drug discrimination results and by the subjective effect self-report results. In the drug discrimination assessments buprenorphine showed a pattern of generalization that was different from that of the other opioid-mixed agonist-antagonists. It did not generalize completely to either pentazocine or butorphanol, but it did generalize to hydromorphone in two studies and partially in a third. Both nalbuphine and pentazocine showed at least partial generalization to butorphanol, but buprenorphine did not. Butorphanol showed little generalization to hydromorphone except in the two-choice hydromorphone vs. saline discrimination in which all the tested mixed agonist-antagonists generalized to hydromorphone. The subjective effect self-report data also revealed a pattern of response to buprenorphine that was different from that to the other mixed agonist-antagonists. In particular, buprenorphine's profile of acute subjective effects was similar to that of hydromorphone. There were dose-related increases on various scales reflecting positive subjective effects, with little evidence of the dysphoric effects that are characteristic of high doses of the other mixed agonist-antagonists. These data are compatible with the view that buprenorphine is a partial agonist at the mu-receptor. Although they do not demonstrate the ceiling on magnitude of pharmacological effects that would be characteristic of a partial agonist, they do demonstrate that buprenorphine's profile of activity--both stimulus effects and subjective effects--is similar to that of the pure mu-agonist hydromorphone.


Mice deficient for Rb are nonviable and show defects in neurogenesis and haematopoiesis. The retinoblastoma gene, a prototypic tumour-suppressor gene, encodes a nuclear phosphoprotein (Rb). To understand better the role of Rb in development and in tumorigenesis, mice with an insertional mutation in exon 20 of the Rb-1 locus were generated. Homozygous mutants die before the 16th embryonic day with multiple defects. The haematopoietic system is abnormal; there is a significant increase in the number of immature nucleated erythrocytes. In the nervous system, ectopic mitoses and massive cell death are found, particularly in the hindbrain. All spinal ganglion cells die, but the neural retina is unaffected. Transfer of the human retinoblastoma (RB) mini-transgene into the mutant mice corrects the developmental defects. Thus, Rb is essential for normal mouse development.


Effects of an Rb mutation in the mouse.

Effects of an Rb mutation in the mouse. The retinoblastoma gene is mutated in several types of human cancer and is the best characterized of the tumour-suppressor genes. A mouse strain has been constructed in which one allele of Rb is disrupted. These heterozygous animals are not predisposed to retinoblastoma, but some display pituitary tumours arising from cells in which the wild-type Rb allele is absent. Embryos homozygous for the mutation die between days 14 and 15 of gestation, exhibiting neuronal cell death and defective erythropoiesis.


Predictable eye-head coordination during driving. Large changes in the direction of gaze are made with a combination of fast saccadic eye movements and rather slower head movements. Since the first study on freely moving subjects, most authors have agreed that the head movement component of gaze is very variable, with a high 'volitional' component. But in some circumstances head and eye movements can be quite predictable, for example when a subject is asked to shift gaze as quickly as possible. Under these conditions, laboratory studies have shown that the eye and head motor-systems both receive gaze-change commands, although they execute them in rather different ways. Here I reconsider the way gaze direction is changed during free movement, but in the performance of a task where the subject is too busy to exert conscious control over head or eye movements. Using a new portable and inexpensive method for recording head and eye movements, I examine the oculomotor behaviour of car drivers, particularly during the large gaze changes made at road junctions. The results show that the pattern of eye and head movements is highly predictable, given only the sequence of gaze targets.


Deficiency of the 50K dystrophin-associated glycoprotein in severe childhood autosomal recessive muscular dystrophy. X-linked recessive Duchenne muscular dystrophy (DMD) is caused by the absence of dystrophin, a membrane cytoskeletal protein. Dystrophin is associated with a large oligomeric complex of sarcolemmal glycoprotein. The dystrophin-glycoprotein complex has been proposed to span the sarcolemma to provide a link between the subsarcolemmal cytoskeleton and the extracellular matrix component, laminin. In DMD, the absence of dystrophin leads to a large reduction in all of the dystrophin-associated protein. We have investigated the possibility that a deficiency of a dystrophin-associated protein could be the cause of severe childhood autosomal recessive muscular dystrophy (SCARMD) with a DMD-like phenotype. Here we report the specific deficiency of the 50K dystrophin-associated glycoprotein (M(r) 50,000) in sarcolemma of SCARMD patients. Therefore, the loss of this glycoprotein is a common denominator of the pathological process leading to muscle cell necrosis in two forms of muscular dystrophy, DMD and SCARMD.


Isolation and quantification of soluble Alzheimer's beta-peptide from biological fluids. Cerebral deposition of the beta-amyloid peptide (A beta) is an invariant feature of Alzheimer's disease. Since the original isolation and characterization of A beta (ref. 1) and the subsequent cloning of its precursor protein, no direct evidence for the actual production of discrete A beta has been reported. Here we investigate whether A beta is present in human biological fluids using antibodies specific for an epitope within A beta that spans the site of normal constitutive cleavage. These antibodies were used to construct a sandwich-type enzyme-linked immunosorbent assay that detects A beta in cerebrospinal fluid, plasma and conditioned medium of human mixed-brain cells grown in vitro (see also ref. 14). By affinity chromatography, we have purified and sequenced A beta and a novel A beta fragment from human cerebrospinal fluid and conditioned medium of human mixed-brain cell cultures. These findings demonstrate that A beta is produced and released both in vivo and in vitro. These observations offer new opportunities for developing diagnostic tests for Alzheimer's disease and therapeutic strategies aimed at reducing the cerebral deposition of A beta.


Requirement for a functional Rb-1 gene in murine development. Human retinoblastomas can occur both as hereditary and as sporadic cases. Knudson's proposal that they result from two mutational events, of which one is present in the germ line in hereditary cases, has been confirmed by more recent molecular analysis, which has shown both events to involve loss or mutational inactivation of the same gene, RB-1 (ref. 2). RB-1 heterozygosity also predisposes to osteosarcoma, and RB-1 allele losses are seen in sporadic lung, breast, prostate and bladder carcinomas. RB-1 is expressed in most, if not all, tissues and codes for a nuclear phosphoprotein which becomes hypophosphorylated in the G0 growth arrest state and in the G1 phase of the cell cycle. To gain a further insight into the role of RB-1 we and other groups have generated mice carrying an inactivated allele of the homologous gene, Rb-1 (ref. 10), by gene targeting. We report here that young heterozygous mice do not appear abnormal and do not develop retinoblastoma at a detectable frequency. However, homozygous mutant embryos fail to reach term and show a number of abnormalities in neural and haematopoietic development. Broadly similar results are reported by the other groups.


Inefficient positive selection of T cells directed by haematopoietic cells. Intrathymic differentiation of alpha beta TCR+ T cells depends on positive selection of CD4+CD8+ thymocytes by thymic major histocompatibility complex (MHC) molecules. Positive selection allows the maturation of only those T cells capable of restricted antigen recognition in the context of the hosts' MHC alleles. Studies of normal or T-cell receptor-transgenic mice engrafted with MHC-different bone marrow or thymuses support the conclusion that positive selection is directed by MHC molecules expressed on non-haematopoietic cells, presumably thymic epithelial cells. Here we, present contrary evidence that class I MHC molecules expressed by haematopoietic cell types direct positive selection of CD8+ T cells, though at a reduced rate compared with positive selection directed by thymic epithelial cells. The identity of cell types that direct positive selection bears directly on mechanistic models of the process, including the idea that thymic epithelial cell MHC molecules uniquely present specialized peptides that mediate positive selection, and the notion that thymic epithelial cells express unique differentiation-inducing cell surface molecules.


The candidate oncoprotein Bcl-3 is an antagonist of p50/NF-kappa B-mediated inhibition. The candidate oncogene bcl-3 was discovered as a translocation into the immunoglobulin alpha-locus in some cases of B-cell chronic lymphocytic leukaemias. The protein Bcl-3 contains seven so-called ankyrin repeats. Similar repeat motifs are found in a number of diverse regulatory proteins but the motifs of Bcl-3 are most closely related to those found in I kappa B proteins in which the ankyrin repeat domain is thought to be directly involved in inhibition of NF-kappa B activity. No biological function has yet been described for Bcl-3, but it was noted recently that Bcl-3 interferes with DNA-binding of the p50 subunit of NF-kappa B in vitro. Here we demonstrate that Bcl-3 can aid kappa B site-dependent transcription in vivo by counteracting the inhibitory effects of p50/NF-kappa B homodimers. Bcl-3 may therefore aid activation of select NF-kappa B-regulated genes, including those of the human immunodeficiency virus.


Continuum of overlapping clones spanning the entire human chromosome 21q. A continuous array of overlapping clones covering the entire human chromosome 21q was constructed from human yeast artificial chromosome libraries using sequence-tagged sites as landmarks specifically detected by polymerase chain reaction. The yeast artificial chromosome contiguous unit starts with pericentromeric and ends with subtelomeric loci of 21q. The resulting order of sequence-tagged sites is consistent with other physical and genetic mapping data. This set of overlapping clones will promote our knowledge of the structure of this chromosome and the function of its genes.


Crystal structure of the met repressor-operator complex at 2.8 A resolution reveals DNA recognition by beta-strands. The crystal structure of the met repressor-operator complex shows two dimeric repressor molecules bound to adjacent sites 8 base pairs apart on an 18-base-pair DNA fragment. Sequence specificity is achieved by insertion of double-stranded antiparallel protein beta-ribbons into the major groove of B-form DNA, with direct hydrogen-bonding between amino-acid side chains and the base pairs. The repressor also recognizes sequence-dependent distortion or flexibility of the operator phosphate backbone, conferring specificity even for inaccessible base pairs.


Parents suppress reproduction and stimulate dispersal in opposite-sex juvenile white-footed mice. Juvenile dispersal is sex-biased in many mammals and birds: one sex often disperses more often or farther than the other. Two hypotheses are generally presented for sex-biased dispersal. The first holds that juvenile dispersal reduces reproductive and/or resource competition between parents and same-sexed offspring. If so, presence of a parent on the natal home range should both promote dispersal of same-sex offspring and suppress reproduction of those that remain. The second is that juvenile dispersal reduces matings between parents and offspring, thus decreasing the likelihood of inbreeding depression. If so, presence of a parent should favour dispersal and reproductive suppression of offspring of the opposite sex. Here I present evidence that juvenile dispersal in white-footed mice, Peromyscus leucopus, is due to inbreeding avoidance. When population density was high, experimental removal of one parent delayed dispersal of opposite-sexed offspring and only the presence of the parents of opposite sex suppressed juvenile reproduction.


Parental origin of chromosomes involved in the translocation t(9;22). Functionally equivalent genetic maternal can be labelled by an epigenetic marking process and used differentially depending on whether its origin is maternal or paternal. This phenomenon is known as genomic imprinting and is manifested at either the chromosomal or gene level. Genomic imprinting seems to play an important role in cancer predisposition syndromes, and phenotypic consequences are evident in constitutional deletion syndromes and uniparental disomies. Moreover, there seems to be a preferential retention of paternal alleles in sporadic tumours such as Wilms' tumour, rhabdomyosarcoma, osteosarcoma and retinoblastoma. To investigate whether chromosomes involved in acquired abnormalities of haematologic neoplasms show a similar 'parent of origin' bias, we studied the inheritance of the translocated chromosomes 9 and 22 in cases of Philadelphia-chromosome-positive leukaemia, using unique specific chromosome band polymorphisms. Here we show that the translocated chromosome 9 was of paternal origin, whereas the translocated chromosomes 22 were derived exclusively from the maternal copy, in 11 cases with reliable polymorphisms. Our data therefore provide evidence that imprinting phenomena may play an important role in acquired tumour-specific chromosome rearrangements.


Evidence for cooperative interactions in potassium channel gating. Cloning and expression of voltage-activated potassium ion-channel complementary DNAs has confirmed that these channels are composed of four identical subunits, each containing a voltage sensor. It has been generally accepted that the voltage sensors must reach a permissive state through one or more conformational ('gating') transitions before the channel can open. To test whether each subunit gates independently, we have constructed cDNAs encoding four subunits on a single polypeptide chain, enabling us to specify the subunit stoichiometry. The gating of heterotetramers made up from combinations of subunits with different gating phenotypes strongly suggests that individual subunits gate cooperatively, rather than independently. Nonindependent subunit gating is consistent with measurements of the kinetics of K(+)-channel gating currents and in line with the widespread subunit cooperativity observed in other multisubunit proteins.


Transcriptional activation by the human c-Myc oncoprotein in yeast requires interaction with Max. The c-myc protein (Myc) contains an amino-terminal transcriptional activation domain and a carboxy-terminal basic helix-loop-helix-leucine zipper (bHLH-Z) domain that directs dimerization of Myc with its partner, the max protein (Max), and promotes DNA binding to sites containing a CACGTG core consensus sequence. Despite these characteristics and the observation that Myc can modulate gene expression, a direct role for Myc or Max as transcription factors has never been demonstrated. Here we use Saccharomyces cerevisiae as an in vivo model system to show that the Myc protein is a sequence-specific transcriptional activator whose DNA binding is strictly dependent on dimerization with Max. Transactivation is mediated by the amino-terminal domain of Myc. We find that Max homodimers bind to the same DNA sequence as Myc+Max but that they fail to transactivate and thus can antagonize Myc+Max function. We also show that the Max HLH-Z domain has a higher affinity for the Myc HLH-Z domain than for itself, and suggest that the heterodimeric Myc+Max activator forms preferentially at equilibrium.


Myc and Max proteins possess distinct transcriptional activities. The Myc family proteins are thought to be involved in transcription because they have both a carboxy-terminal basic-helix-loop-helix-zipper (bHLH-Z) domain, common to a large class of transcription factors, and an amino-terminal fragment which, for c-Myc, has transactivating function when assayed in chimaeric constructs. In addition, c-, N- and L-Myc proteins heterodimerize, in vitro and in vivo, with the bHLH-Z protein Max. In vitro, Max homodimerizes but preferentially associates with Myc, which homodimerizes poorly. Furthermore Myc-Max heterodimers specifically bind the nucleotide sequence CACGTG with higher affinity than either homodimer alone. The identification of Max and the specific DNA-binding activities of Myc and Max provides an opportunity for directly testing the transcriptional activities of these proteins in mammalian cells. We report here that Myc overexpression activates, whereas Max overexpression represses, transcription of a reporter gene. Max-induced repression is relieved by overexpression of c-Myc. Repression requires the DNA-binding domain of Max, whereas relief of repression requires the dimerization and transcriptional activation activities of Myc. Both effects require Myc-Max-binding sites in the reporter gene.


Probing met repressor-operator recognition in solution. The three-dimensional crystal structure of the Escherichia coli methionine repressor, MetJ, complexed with a DNA operator fragment is described in an accompanying article. The complex exhibits several novel features of DNA-protein interaction. DNA sequence recognition is achieved largely by hydrogen-bond contacts between the bases and amino-acid side chains located on a beta-ribbon, a mode of recognition previously hypothesized on the basis of modelling of idealized beta-strands and DNA, and mutagenesis of the Salmonella phage P22 repressors Arc and Mnt. The complex comprises a pair of MetJ repressor dimers which bind to adjacent met-box sites on the DNA, and contact each other by means of a pair of antiparallel alpha-helices. Here we assess the importance of these contacts, and also of contacts that would be made between the C-helices of the protein and DNA in a previous model of the complex, by studying mutations aimed at disrupting them. The role of the carboxy-terminal helix face in operator binding was unclear, but we demonstrate that recognition of operator sequences occurs through side chains in the beta-strand motif and that dimer-dimer interactions are required for effective repression.


Marsupial Y chromosome encodes a homologue of the mouse Y-linked candidate spermatogenesis gene Ube1y. The mammalian subclass Theria consists of infraclasses Metatheria (marsupials) and Eutheria ('placentals') which diverged from each other 120-150 million years before present (Myr BP). Both infraclasses have Y chromosome-dependent testis determination but direct molecular evidence linking the Metatherian and Eutherian Y chromosomes is lacking. Comparative analyses indicate that three mammalian genes have remained Y-linked for at least 80 Myr, since the divergence of the Eutherian orders from a common ancestor. These are Zfy, a gene encoding a transcription factor of the zinc-finger type; Sry, the putative primary testis-determining gene; and Ube1y (formerly Sby or A1s9Y-1), a candidate for the mouse spermatogenesis gene Spy, encoding a ubiquitin-activating enzyme E1 homologue. Although in marspials Zfy homologues are autosomal, a Y homologue of Sry has recently been isolated. We report here the identification of a functional marsupial Y-linked homologue of the murine Ube1y gene establishing that Metatherian and Eutherian Y chromosomes diverged from a common ancestor. This extreme conservation indicates that Ube1y plays a critical role in male development.


Evolution of sex determination and the Y chromosome: SRY-related sequences in marsupials. In mammals, testis determination is under the control of the testis-determining factor borne by the Y chromosome. SRY, a gene cloned from the sex-determining region of the human Y chromosome, has been equated with the testis-determining factor in man and mouse. We have used a human SRY probe to identify and clone related genes from the Y chromosome of two marsupial species. Comparisons of eutherian and metatherian Y-located SRY sequences suggest rapid evolution of these genes, especially outside the region encoding the DNA-binding HMG box. The SRY homologues, together with the mouse Ube1y homologues, are the first genes to be identified on the marsupial Y chromosome.


Microtubule-motor activity of a yeast centromere-binding protein complex. During cell division, sister chromosomes segregate from each other on a microtubule-based structure called the mitotic spindle. Proteins bind to the centromere, a region of chromosomal DNA, to form the kinetochore, which mediates chromosome attachment to the mitotic spindle microtubules. In the budding yeast Saccharomyces cerevisiae, genetic analysis has shown that the 28-basepair (bp) CDEIII region of the 125-bp centromere DNA sequence (CEN sequence) is the main region controlling chromosome segregation in vivo. Therefore it is likely that proteins binding to the CDEIII region link the centromeres to the microtubules during mitosis. A complex of proteins (CBF3) that binds specifically to the CDEIII DNA sequence has been isolated by affinity chromatography. Here we describe kinetochore function in vitro. The CBF3 complex can link DNA to microtubules, and the complex contains a minus-end-directed microtubule-based motor. We suggest that microtubule-based motors form the fundamental link between microtubules and chromosomes at mitosis.


CENP-E is a putative kinetochore motor that accumulates just before mitosis. The mechanics of chromosome movement, mitotic spindle assembly and spindle elongation have long been central questions of cell biology. After attachment in prometaphase of a microtubule from one pole, duplicated chromosome pairs travel towards the pole in a rapid but discontinuous motion. This is followed by a slower congression towards the midplate as the chromosome pair orients with each kinetochore attached to the microtubules from the nearest pole. The pairs disjoin at anaphase and translocate to opposite poles and the interpolar distance increases. Here we identify CENP-E as a kinesin-like motor protein (M(r) 312,000) that accumulates in the G2 phase of the cell cycle. CENP-E associates with kinetochores during congression, relocates to the spindle midzone at anaphase, and is quantitatively discarded at the end of the cell division. CENP-E is likely to be one of the motors responsible for mammalian chromosome movement and/or spindle elongation.


Mitotic spindle organization by a plus-end-directed microtubule motor. Intracellular microtubule motor proteins may direct the motile properties and/or morphogenesis of the mitotic spindle (reviewed in ref. 3). The recent identification of kinesin-like proteins important for mitosis or meiosis indicates that kinesin-related proteins may play a universal role in eukaryotic cell division, but the precise function of such proteins in mitosis remains unknown. Here we use an in vitro assay for spindle assembly, derived from Xenopus egg extracts, to investigate the role of Eg5, a kinesin-like protein in Xenopus eggs. Eg5 is localized along spindle microtubules, and particularly enriched near spindle poles. Immunodepletion of Eg5 from egg extracts markedly reduces the extent of spindle formation in extracts, as does direct addition of anti-Eg5 antibodies. We also demonstrate that Eg5 is a plus-end-directed microtubule motor in vitro. Our results suggest a novel mechanism for the dynamic self-organization of spindle poles in mitosis.


A plus-end-directed motor enzyme that moves antiparallel microtubules in vitro localizes to the interzone of mitotic spindles. Mitosis comprises a complex set of overlapping motile events, many of which involve microtubule-dependent motor enzymes. Here we describe a new member of the kinesin superfamily. The protein was originally identified as a spindle antigen by the CHO1 monoclonal antibody and shown to be required for mitotic progression. We have cloned the gene that encodes this antigen and found that its sequence contains a domain with strong sequence similarity to the motor domain of kinesin-like proteins. The product of this gene, expressed in bacteria, can cross-bridge antiparallel microtubules in vitro, and in the presence of Mg-ATP, microtubules slide over one another in a fashion reminiscent of microtubule movements during spindle elongation.


Autoimmune diabetes as a consequence of locally produced interleukin-2. During cell differentiation in the thymus, self-reactive T cells can be generated. The majority of these seem to be deleted after intrathymic encounter with the relevant autoantigen. As all self antigens are unlikely to be present in the thymus, some autoreactive T cells may escape censorship. Here we study the fate of these cells using transgenic mice expressing the class I molecule H-2Kb (Kb) in the insulin-producing beta-cells of the pancreas. These mice were crossed with mice transgenic for genes encoding a Kb-specific T-cell antigen receptor (TCR) which could be detected using a clonotype-specific monoclonal antibody. Although T cells expressing the highest level of transgenic TCR were deleted intrathymically in double-transgenic mice, Kb-specific T cells were detected in the periphery. These cells caused the rejection of Kb-expressing skin grafts, but ignored islet Kb antigens even after priming. But when double-transgenic mice were crossed with transgenic mice expressing the lymphokine interleukin-2 in the pancreatic beta-cells, there was a rapid onset of diabetes. These results indicate that autoreactive T cells that ignore self antigens may cause autoimmune diabetes when provided with exogenous 'help' in the form of interleukin-2.


Apoptotic cell death induced by c-myc is inhibited by bcl-2. Apoptosis is a form of physiological cell death, characterized by chromatin condensation, cytoplasmic blebbing and DNA fragmentation, which often depends on RNA and protein synthesis by the dying cell. The c-myc proto-oncogene, usually implicated in cell transformation, differentiation and cell-cycle progression also has a central role in some forms of apoptosis. These opposing roles of myc in cell growth and death require that other gene products dictate the outcome of c-Myc expression on a cell. A candidate for such a modifying gene is bcl-2, whose product prolongs cell survival and blocks apoptosis in some systems. Here we demonstrate that Bcl-2 prevents apoptotic death induced by c-Myc, provide a mechanism whereby cells can express c-Myc without undergoing apoptosis, and give a possible explanation for the ability of Bcl-2 to synergize with c-Myc in cell transformation.


Cooperative interaction between c-myc and bcl-2 proto-oncogenes. The bcl-2 proto-oncogene is activated by translocation in a variety of B-lymphoid tumours and synergizes with the c-myc oncogene in tumour progression. The mechanism of synergy is unclear but bcl-2 expression inhibits apoptosis, a property presumably pertinent to its proto-oncogenic mode of action. We have shown that the c-myc gene is a potent inducer of apoptosis, in addition to its established role in mitogenesis. Here we show that expression of the bcl-2 protein, Bcl-2, specifically abrogates c-myc-induced apoptosis without affecting the c-myc mitogenic function. This provides a novel mechanism for oncogene cooperation, of potential importance both in carcinogenesis and in the evolution of drug resistance in tumours.


New drug law to speed scientific review. By charging drug companies 'user fees' that will be spent hiring new staff, the US Food and Drug Administration will reduce the time it takes to review new pharmaceuticals from an average of two years to one.


Biodiversity supported.

Biodiversity supported. Funding for a new programme, with only $1.5 million for grants, is hardly enough to scratch the surface.


HIV: to vaccinate or not to vaccinate?

HIV: to vaccinate or not to vaccinate? "Improbability of effective vaccination against human immunodeficiency virus ...", declares the title of a new paper by Dr Albert Sabin. But three immunologists see flaws in his argument.


Creative blocks: cell-cycle checkpoints and feedback controls. Before division, cells must ensure that they finish DNA replication, DNA repair and chromosome segregation. They do so by using feedback controls which can detect the failure to complete replication, repair or spindle assembly to arrest the progress of the cell cycle at one of three checkpoints. Failures in feedback controls can contribute to the generation of cancer.


Dissociation between mental imagery and object recognition in a brain-damaged patient. Visual imagery is the creation of mental representations that share many features with veridical visual percepts. Studies of normal and brain-damaged people reinforce the view that visual imagery and visual perception are mediated by a common neural substrate and activate the same representations. Thus, brain-damaged patients with intact vision who have an impairment in perception should have impaired visual imagery. Here we present evidence to the contrary from a patient with severely impaired object recognition (visual object agnosia) but with normal mental imagery. He draws objects in considerable detail from memory and uses information derived from mental images in a variety of tasks. In contrast, he cannot identify visually presented objects, even those he has drawn himself. He has normal visual acuity and intact perception of equally complex material in other domains. We conclude that rich internal representations can be activated to support visual imagery even when they cannot support visually mediated perception of objects.


Hippocampus-dependent learning facilitated by a monoclonal antibody or D-cycloserine. Persistent neuronal plasticity, including that observed at some hippocampal synapses, requires N-methyl-D-aspartate (NMDA)-mediated transmission. NMDA receptor activation may be necessary for hippocampus-dependent learning as antagonists block acquisition in many such tasks. The behavioural effects of NMDA agonists are less well defined. We have shown that a monoclonal antibody (B6B21) displaced [3H]-glycine that was bound specifically to the NMDA receptor, and enhanced the opening of its integral cation channel in a glycine-like fashion, effects that were competitively antagonized by 7-chlorokynurenic acid. B6B21 also enhanced long-term potentiation in hippocampal slices. We report here that intraventricular infusions of B6B21 significantly enhances acquisition rates in hippocampus-dependent trace eye blink conditioning in rabbits, halving the number of trials required to reach a criterion of 80% conditioned responses. Peripheral injections of D-cycloserine, a partial agonist of the glycine site on the NMDA receptor which crosses the blood-brain barrier, also doubles rabbits' learning rates. Pseudoconditioning control experiments indicated a lack of nonspecific behavioural sensitization effects. Our data suggest that enhanced activation of the glycine coagonist site on the NMDA receptor/channel complex facilitates one form of associative learning and may be used in other learning tasks.


Oxidative stress and heat shock induce a human gene encoding a protein-tyrosine phosphatase. Reactive oxygen species have been implicated both in the ageing process and in degenerative diseases, including arthritis and cancer. Bacteria adapt to the lethal effects of oxidants such as hydrogen peroxide by inducing the expression of protective stress genes. Analogous responses have been identified in human cells. For example, haem oxygenase is a major stress protein in human cells treated with oxidants, and reactive oxygen intermediates activate NF-kappa B, a transcriptional regulator of genes involved in inflammatory and acute-phase responses. We report here the isolation and characterization of a novel complementary DNA (CL100) corresponding to a messenger RNA that is highly inducible by oxidative stress and heat shock in human skin cells. The cDNA contains an open reading frame specifying a protein of M(r) 39.3K with the structural features of a non-receptor-type protein-tyrosine phosphatase and which has significant amino-acid sequence similarity to a Tyr/Ser-protein phosphatase encoded by the late gene H1 of vaccinia virus. The purified protein encoded by the CL100 open reading frame expressed in bacteria has intrinsic phosphatase activity. Given the relationship between the levels of protein-tyrosine phosphorylation, receptor activity, cellular proliferation and cell-cycle control, the induction of this gene may play an important regulatory role in the human cellular response to environmental stress.


A functional barrier to movement of lipids in polarized neurons. In polarized neurons, axons and dendrites perform different functions, which are reflected in their different molecular organization. Studies on the sorting of viral and endogenous glycoproteins in epithelial cells and hippocampal neurons suggest that there may be similarities in the mechanism of sorting in these two cell types. The mechanisms that maintain the distinct composition of the two plasma membrane domains in these two cell types must, however, be different. We have proposed the existence of a functional barrier at the axonal hillock/initial segment which prevents the intermixing of membrane constituents. Here we test this hypothesis by fusing liposomes containing fluorescent phospholipids into the plasma membrane of polarized hippocampal cells in culture. Fusion was induced by lowering the pH and mediated by influenza virus haemagglutinin expressed on the axonal surface of neurons infected with fowl plague virus. Labelling was found exclusively on axons after fusion. Although the fused lipids were mobile on the axonal membrane, no labelling was detected on the cell body and dendritic surfaces. These results suggest that there is a diffusion barrier at the axonal hillock/initial segment which maintains the compositional differences between the axonal and somatodendritic domains.