Intra- and inter-rater consistency of dual assessment by radiologist and neurologist for evaluating DWI-ASPECTS in ischemic stroke.

OBJECTIVES: To estimate the intra -and inter-rater consistency of radiologist and neurologist working in pairs attributing DWI-ASPECTS (Diffusion Alberta Stroke Program Early CT Score) in patients with acute middle cerebral artery ischemic stroke referred for mechanical thrombectomy, intravenous thrombolysis or bridging therapy. METHODS: Five neurologists and 5 radiologists working in pairs and in hour period scored independently and in two reading sessions anonymized DWI-ASPECTS of 80 patients presenting with acute anterior ischaemic stroke in our center. We measured agreement between pairs using intraclass correlation coefficients (ICCs). A Fleiss kappa was used for dichotomized (0-6;7-10) and trichotomized (0-3;4-6;7-10) ASPECTS. The interrater distribution of the score in the trichotomized (0-3;4-6;7-10) ASPECTS was calculated. We determined the interrater (Cohen kappa) and intrarater (Fleiss kappa) agreement on the ASPECTS regions. RESULTS: The average DWI-ASPECTS was 6.35 (SD±2.44) for the first reading, and 6.47 (SD±2.44) for the second one. The ICC was 0.853 (95%CI, 0.798-0.896) for the interrater, and 0.862 (95%CI, 0.834-0.885) for the intrarater evaluation. Kappa coefficients were high for dichotomized (k=0.75) and trichotomized (k=0.64) ASPECTS. Evaluators agreement on the ASPECTS category (0-3), (4-6) and (7-10) was 88, 76 and 93% respectively. The anatomic region infarcted was well identified (k=0.70-0.77), except for the internal capsula (k=0.57). Interrater agreement was fair for M5 (k=0.37), moderate for internal capsula (0.52) and substantial for the other regions (0.60-0.79). CONCLUSIONS: Reliability of DWI-ASPECTS is good when determined by radiologist and neurologist working in pairs, which corresponds to our current clinical practice. However, discrepancies are possible for cut-off determination, which may impact the indication of thrombectomy, and for the determination of the exact infarcted region. Agreement to propose category (4-6) is lower than for (0-3) and (8-10) ASPECTS categories.

Communicating treatment risks and benefits to cancer patients: a systematic review of communication methods.

PURPOSE: Cancer patients are increasingly involved in decision-making processes. Hence, clinicians need to inform patients about the risks and benefits of different treatment options in order for patients to make well informed decisions. The aim of this review is to determine the effects of methods of communicating prognostic information about (1) disease progression (survival, progression, recurrence and remission), (2) side effects and complications and (3) health-related quality of life (HRQL) on cognitive, affective and behavioral outcomes in cancer patients. METHODS: A literature search was performed to select articles that were published up to  November 2019 and that examined verbal and/or visual risk communication interventions in an oncological clinical setting. RESULTS: The search yielded 14,875 studies; 28 studies were ultimately included. For disease progression information, we found that framing affects treatment choice. Furthermore, limiting the amount of progression information in a graphical display could benefit patients' understanding of risks and benefits. For prognostic information about side effects and complications, precise and defined risk information was better understood than information presented in words. When displaying HRQL data, no consensus was found on which graph type to use. CONCLUSION: Great heterogeneity in the results and methodology and in the compared communication formats precluded us from drawing any further conclusions. Practical implications for clinicians are to consider the effects that different types of framing might have on the patient and to not rely exclusively on words to describe risks, but rather include at least some form of numbers or visualization.

Management strategies to minimize the use of synthetic chemical acaricides in the control of the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini, 1888) in an area highly favourable for its development in Argentina.

The aim of this work was to test the efficacy of winter-spring control strategies against Rhipicephalus (Boophilus) microplus (Canestrini, 1888) (Ixodida: Ixodidae) in an area highly favourable for its development in Argentina. Control schemes using three or four annual applications of synthetic acaricides were evaluated. Furthermore, the dynamics of the non-parasitic phases of R. microplus were analysed to provide a framework for the application of pasture spelling as a tool for tick control. The treatment schemes provided appropriate levels of efficacy against R. microplus and also prevented the occurrence of the major peak in abundance of this tick in autumn. A significant overall effect against R. microplus can be achieved when the control strategies tested in this study are applied within the area most ecologically favourable for this tick in Argentina. Analysis of the dynamics of the non-parasitic phase of R. microplus indicates that the spelling period required to achieve a significant reduction of larvae in pastures fluctuates between 12 and 17 weeks if spelling is initiated in spring or early summer, but between 20 and 28 weeks if spelling is started in late summer, autumn or winter.

Efficacy of winter-spring strategic control against Rhipicephalus (Boophilus) microplus infestations on cattle in an area with ecological conditions highly favourable for the tick in northeast Argentina.

This work was performed to test the efficacy of winter-spring control strategies against Rhipicephalus (Boophilus) microplus (Ixodida: Ixodidae) infestations on cattle in the area ecologically most favourable for the development of this tick in Argentina. Two control schemes using three and four annual applications of acaricides, respectively, were evaluated. Animals in Group 1 were treated with ivermectin 3.15% on day 0, fluazuron on day 34, and fipronil on day 85. Animals in Group 2 were treated with ivermectin 3.15% on day 0, fluazuron on day 34, flumethrin on day 85, and fipronil on day 114. Animals in Group 3 represented the control group. Both treatment schemes provided appropriate levels of efficacy against R. microplus and also prevented the occurrence of the major peak in the frequency of this tick in autumn. The two treatment schemes were similar in terms of efficacy and thus the addition of a fourth treatment does not seem to confer any further advantage. The results of this work indicate that these strategic control methods provide appropriate levels of control against R. microplus.

Bleeding complications and antithrombotic treatment in 264 pregnancies in antiphospholipid syndrome.

Purpose The purpose of this study was to evaluate the safety of antithrombotic treatments prescribed during pregnancy in patients with antiphospholipid syndrome (APS). Methods This international, multicenter study included two cohorts of patients: a retrospective French cohort and a prospective US cohort (PROMISSE study). Inclusion criteria were (1) APS (Sydney criteria), (2) live pregnancy at 12 weeks of gestation (WG) with (3) follow-up data until six weeks post-partum. According to APS standard of care, patients were treated with aspirin and/or low-molecular weight heparin (LMWH) at prophylactic (pure obstetric APS) or therapeutic doses (history of thrombosis). Major bleeding was defined as abnormal blood loss during the pregnancy and/or post-partum period requiring intervention for hemostasis or transfusion, or during the peripartum period greater than 500 mL and/or requiring surgery or transfusion. Other bleeding events were classified as minor. Results Two hundred and sixty-four pregnancies (87 prospectively collected) in 204 patients were included (46% with history of thrombosis, 23% with associated systemic lupus). During pregnancy, treatment included LMWH ( n = 253; 96%) or low-dose aspirin ( n = 223; 84%), and 215 (81%) patients received both therapies. The live birth rate was 89% and 82% in the retrospective and prospective cohorts, respectively. Adverse pregnancy outcomes occurred in 28% of the retrospective cohort and in 40% of the prospective cohort. No maternal death was observed in either cohort. A combined total of 45 hemorrhagic events (25%) occurred in the retrospective cohort, but major bleeding was reported in only six pregnancies (3%). Neither heparin nor aspirin alone nor combined therapy increased the risk of hemorrhage. We also did not observe an increased rate of bleeding in the case of a short interval between last LMWH (less than 24 hours) or aspirin (less than five days) doses and delivery. Only emergency Caesarean section was significantly associated with an increased risk of bleeding (odds ratio (OR) 5.03 (1.41-17.96); p=.016). In the prospective cohort, only one minor bleeding event was reported (vaginal bleeding). Conclusion Our findings support the safety of antithrombotic therapy with aspirin and/or LMWH during pregnancy in high-risk women with APS, and highlight the need for better treatments to improve pregnancy outcomes in APS. PROMISSE Study ClinicalTrials.gov identifier: NCT00198068.

Reduced mortality by meeting guideline criteria before using recombinant activated factor VII in severe trauma patients with massive bleeding.

BACKGROUND: Management of trauma patients with severe bleeding has led to criteria before considering use of recombinant activated factor VII (rFVIIa), including haemoglobin >8 g dl-1, serum fibrinogen ≥1.0 g l-1, platelets >50,000 x 109 l-1, arterial pH ≥ 7.20, and body temperature ≥34 °C. We hypothesized that meeting these criteria is associated with improved outcomes. METHODS: In this prospective cohort study of 26 French trauma centres, subjects were included if they received rFVIIa for persistent massive bleeding despite appropriate care after severe blunt and/or penetrating trauma. RESULTS: After surgery and/or embolization as haemostatic interventions, 112 subjects received a first dose of 103 µg kg-1 rFVIIa (82-200) (median, 25th-75th percentile) at 420 min (285-647) post-trauma. Of these, 71 (63%) "responders" were still alive at 24h post-trauma and had their transfusion requirements reduced by > 2 packed red blood cell units after rFVIIa treatment. Mortality was 54% on day 30 post-trauma. There were 21%, 44% and 35% subjects who fulfilled 0-1, 2-3 or 4-5, respectively, of the guidelines before receiving rFVIIa. Survival at day 30 was 13%, 49% and 64% and the proportion of responders was 39%, 64% and 82%, when subjects fulfilled 0-1, 2-3 or 4-5 conditions, respectively (both P <0.01). CONCLUSIONS: In actively bleeding trauma patients, meeting guideline criteria before considering rFVIIa was associated with lower mortality and a higher proportion of responders to the rFVIIa.

Pregnancy and contraception in systemic and cutaneous lupus erythematosus.

A causal link has long been described between estrogen and systemic lupus erythematosus activity. Contraceptive and pregnancy management is now common for lupus patients, but pregnancy continues to be associated with higher maternal and fetal mortality/morbidity in systemic lupus erythematosus patients than among the general population. Potential complications include lupus flares, obstetric complications (fetal loss, in utero growth retardation, premature birth) and neonatal lupus syndrome. Association with antiphospholipid antibodies or antiphospholipid syndrome increases the risk of obstetric complications. Anti-SSA and/or anti-SSB antibodies put fetuses at risk for neonatal lupus. Improving the outcome of such pregnancies depends upon optimal systematic planning of pregnancy at a preconception counseling visit coupled with a multidisciplinary approach. Absence of lupus activity, use of appropriate medication during pregnancy based on the patient's medical history and risk factors, and regular monitoring constitute the best tools for achieving a favorable outcome in such high-risk pregnancies. The aim of this review is to provide an update on the management of contraception and pregnancy in systemic lupus erythematosus, cutaneous lupus and/or antiphospholipid syndrome in order to reduce the risk of complications and to ensure the best maternal and fetal prognosis.

Colchicine: a simple and effective treatment for pericarditis in systemic lupus erythematosus? A report of 10 cases.

OBJECTIVES: Pericardial involvement is a frequent manifestation of systemic lupus erythematosus (SLE). Growing evidence suggests that colchicine may be useful for acute or recurrent pericarditis. We report for the first time a series of 10 consecutive cases of SLE with pericarditis treated with colchicine. METHODS: Inclusion criteria in this retrospective study were diagnosis of SLE, pericarditis and receiving colchicine. RESULTS: We included 10 consecutive cases of SLE with pericarditis treated with colchicine (nine women, mean age at the index pericarditis 35 ± 12 years). Pericarditis was the initial manifestation of SLE for two patients, whereas eight patients had SLE lasting for a median of 2.5 years (15 days to 13 years) and had received prednisone (n = 7, 2-30 mg/d), hydroxychloroquine (n = 7), azathioprine (n = 3), methotrexate (n = 2), and mycophenolate mofetil (n = 1). For six patients, pericarditis was associated with other SLE manifestations. Altogether, colchicine avoided the use (n = 2) or increase in dosage (n = 5) of steroids in seven cases; the increase in steroids dosage was minimal for two patients. Colchicine 1 mg was given for a median of 39 days (10 days to 54 months). Symptoms completely resolved after a median of 2.5 days (1-30 days) after initiation of colchicine. Colchicine was maintained or resumed in six patients to prevent recurrence, with no further relapse. CONCLUSIONS: Colchicine may be safe and effective in treating SLE pericarditis and used as a steroids-sparing agent. These preliminary results need to be confirmed in a larger study with longer follow-up.

Myosin light chain kinase controls voltage-dependent calcium channels in vascular smooth muscle.

The Ca(2+)-dependent kinase myosin light chain kinase (MLCK) is the activator of smooth muscle contraction. In addition, it has been reported to be involved in Ca(2+) channel regulation in cultured cells, and we previously showed that the MLCK inhibitor ML-7 decreases arginine vasopressin (AVP)-induced Ca(2+) influx in rat aorta. This study was designed to investigate whether MLCK is involved in Ca(2+) regulation in resistance artery smooth muscle cell, which plays a major role in the control of blood pressure. As ML compounds were shown to have off-target effects, MLCK was downregulated by transfection with a small interfering RNA targeting MLCK (MLCK-siRNA) in rat small resistance mesenteric artery (RMA) and in the rat embryonic aortic cell line A7r5. Noradrenaline-induced contraction and Ca(2+) signal were significantly depressed in MLCK-siRNA compared to scramble-siRNA-transfected RMA. Contraction and Ca(2+) signal induced by high KCl and voltage-activated Ca(2+) current were also significantly decreased in MLCK-siRNA-transfected RMA, suggesting that MLCK depletion modifies voltage-operated Ca(2+) channels. KCl- and AVP-induced Ca(2+) signals and voltage-activated Ca(2+) current were decreased in MLCK-depleted A7r5 cells. Eventually, real-time quantitative PCR analysis indicated that in A7r5, MLCK controlled mRNA expression of CaV1.2 (L-type) and CaV3.1 (T-type) voltage-dependent Ca(2+) channels. Our results suggest that MLCK controls the transcription of voltage-dependent Ca(2+) channels in vascular smooth muscle cells.

French practical guidelines for the diagnosis and management of relapsing polychondritis.

Relapsing polychondritis is a rare systemic disease. It usually begins in middle-aged individuals. This diagnosis is mainly suggested in the presence of chondritis, i.e. inflammatory flares on the cartilage, in particular of the ears, nose or respiratory tract, and more rarely in the presence of other manifestations. The formal diagnosis of relapsing polychondritis cannot be established with certainty before the onset of chondritis, which can sometimes occur several years after the first signs. No laboratory test is specific of relapsing polychondritis, the diagnosis is usually based on clinical evidence and the elimination of differential diagnoses. Relapsing polychondritis is a long-lasting and often unpredictable disease, evolving in the form of relapses interspersed with periods of remission that can be very prolonged. Its management is not codified and depends on the nature of the patient's symptoms and association or not with myelodysplasia/vacuoles, E1 enzyme, X linked, autoinflammatory, somatic (VEXAS). Some minor forms can be treated with non-steroidal anti-inflammatory drugs, or a short course of corticosteroids with possibly a background treatment of colchicine. However, the treatment strategy is often based on the lowest possible dosage of corticosteroids combined with background treatment with conventional immunosuppressants (e.g. methotrexate, azathioprine, mycophenolate mofetil, rarely cyclophosphamide) or targeted therapies. Specific strategies are required if relapsing polychondritis is associated with myelodysplasia/VEXAS. Forms limited to the cartilage of the nose or ears have a good prognosis. Involvement of the cartilage of the respiratory tract, cardiovascular involvement, and association with myelodysplasia/VEXAS (more frequent in men over 50years of age) are detrimental to the prognosis of the disease.

Factors influencing the efficacy of two injections of a pandemic 2009 influenza A (H1N1) nonadjuvanted vaccine in systemic lupus erythematosus.

OBJECTIVE: To assess the factors influencing the efficacy of 2 injections of a pandemic 2009 influenza A (H1N1) vaccine in patients with systemic lupus erythematosus (SLE). METHODS: We conducted a single-center, observational prospective study of 111 patients who were vaccinated with a monovalent, inactivated, nonadjuvanted, split-virus vaccine during December 2009 and January 2010 and received a second dose of vaccine 3 weeks later. The antibody response was evaluated using the hemagglutination inhibition assay according to the guidelines recommended for the pandemic vaccine, consisting of 3 immunogenicity criteria (i.e., a seroprotection rate of 70%, a seroconversion rate of 40%, and a geometric mean ratio [GMR] of 2.5). RESULTS: The 3 immunogenicity criteria were met on day 42 (seroprotection rate 80.0% [95% confidence interval (95% CI) 72.5-87.5%], seroconversion rate 71.8% [95% CI 63.4-80.2%], and GMR 10.3 [95% CI 2.9-14.2]), while only 2 criteria were met on day 21 (seroprotection rate 66.7% [95% CI 57.9-75.4%], seroconversion rate 60.4% [95% CI 51.3-69.5%], and GMR 8.5 [95% CI 3.2-12.0]). The vaccine was well tolerated. Disease activity, assessed by the Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index, the British Isles Lupus Assessment Group score, and the Systemic Lupus Activity Questionnaire, did not increase. In the multivariate analysis, vaccination failure was significantly associated with immunosuppressive treatment or a lymphocyte count of ≤ 1.0 × 109/liter. The second injection significantly increased the immunogenicity in these subgroups, but not high enough to fulfill the seroprotection criterion in patients receiving immunosuppressive treatment. CONCLUSION: Our findings indicate that the efficacy of the vaccine was impaired in patients who were receiving immunosuppressive drugs or who had lymphopenia. A second injection increased vaccine immunogenicity without reaching all efficacy criteria for a pandemic vaccine in patients receiving an immunosuppressive agent. These results open possibilities for improving anti-influenza vaccination in SLE.

[Heart involvement in systemic lupus erythematosus and antiphospholipid syndrome]. / Cœur et médecine interne : lupus systémique et syndrome des antiphospholipides.

Cardiac involvement in systemic lupus (SL) and antiphospholipid syndrome (APS) can be due to variables and involve different presentations. Pericarditis is the most common lupus manifestation and occurs in 16% to 25% of patients. While corticosteroids are usually very effective, colchicine may avoid steroids and prevent relapse. Myocarditis during SL is rare and often inaugural. They may manifest as chest pain, acute heart failure, arrhythmias or conduction disturbances, and may progress to dilated cardiomyopathy and/or permanent heart failure. Their prognosis is however generally good, even in the absence of treatment with cyclophosphamide for the less serious forms. Finally, coronary involvement in SL is most often due to atherosclerotic, thrombotic origin (generally in the context of associated APS), and exceptionally explained by coronary vasculitis. During APS, valve disease is frequent and usually asymptomatic. Thrombotic damage can be (1) coronary, typically manifesting as a myocardial infarction in a young subject with healthy coronary arteries, (2) much more rarely intracardiac, or (3) microcirculatory, generally as part of a catastrophic antiphospholipid syndrome (CAPS) leading to a multiorgan failure. Finally, iatrogenic cardiac manifestations can exceptionally be seen during treatment with cyclophosphamide or antimalarials characterized by conduction disorders and/or heart failure.

PrPSc accumulation in myocytes from sheep incubating natural scrapie.

Because variant Creutzfeldt-Jakob disease (vCJD) in humans probably results from consumption of products contaminated with tissue from animals with bovine spongiform encephalopathy, whether infectious prion protein is present in ruminant muscles is a crucial question. Here we show that experimentally and naturally scrapie-affected sheep accumulate the prion protein PrP(Sc) in a myocyte subset. In naturally infected sheep, PrP(Sc) is detectable in muscle several months before clinical disease onset. The relative amounts of PrP(Sc) suggest a 5,000-fold lower infectivity for muscle as compared to brain.

[Evaluation of a dysphonic population. Interest of a therapeutic team composed by the phoniatrician and the speech therapist]. / Evaluation d'une population de dysphoniques suivis en équipe phoniatrie/orthophonie.

PURPOSE: To evaluate a population of dysphonic treated in rehabilitation by comparing the VHI score and GRB scale. MATERIALS AND METHODS: 300 questionnaires were completed, only 42 cases were matched before and after 15 rehabilitation sessions; that is 84 questionnaires. Patients were divided into two groups: group 1 (impaired mobility of the vocal cords), group 2 (benign mucosal lesions). All patients completed a VHI questionnaire, a questionnaire evaluating subjective voice abuse (SSVS), a GRB score. The two tests were correlated to the diagnosis of voice pathology but also used for follow up after voice therapy. The tests used for statistical studies were: comparison by pathology by unpaired series tests (theoretical deviation=0); mean tests, Wilcoxon type. RESULTS: Patients were more handicapped by impaired mobility of the vocal cord than by a nodule or a cyst. The patients' vocal handicap (VHI) was significantly lower after 15 therapy sessions, in all of its components. The perceptual evaluation GRB is also significantly better for these patients after 15 therapy sessions. We could not demonstrate a favorable evolution, that is a diminution of the SSVS before and after 15 sessions. CONCLUSION: The efficacy of speech therapy for certain vocal cord pathologies has been demonstrated both in respect of the Vocal Handicap felt by the patient as well as the Hirano scale.

COVID-19 and ENT Surgery.

In Otorhinolaryngology - Head and Neck Surgery, clinical examination and invasive procedures on the respiratory tract and on airway-connected cavities, such as paranasal sinuses and the middle ear, expose people to direct transmission of SARS-CoV-2 by inhalation or ocular projection of contaminated droplets, and to indirect transmission by contact with contaminated hands, objects or surfaces. Estimating an R0 of COVID-19 at around 3 justified postponing non-urgent face-to-face consultations and expanding the use of teleconsultation in order to limit the risks of SARS-CoV-2 infection of patients or health workers and comply with the lockdown. The health authority recommends cancellation of all medical or surgical activities, which are not urgent as long as this does not involve a loss of chance for the patient. The purpose of this cancellation is to significantly increase critical care capacity, prioritise the reception of patients with COVID-19, prioritise the allocation of staff and provision of the equipment necessary for their medical or surgical management, and contribute to the smooth running of downstream critical care within their establishment. Another goal is to reduce the risks of patient contamination within healthcare facilities. This document provides guidance on how to proceed with and adapt ENT surgery in the current pandemic context, as well as on the management of postponed operations. This best practice advice must of course be adapted in each region according to the development of the epidemic and pre-existing arrangements. Their local application can only be decided within the framework of collaboration between the ENT teams, the operational hygiene units and all the other specialties concerned.

Best practice recommendations: ENT consultations during the COVID-19 pandemic.

These best practice recommendations for ENT consultations during the COVID-19 pandemic have been drawn up because ENT examinations and treatments are at risk of contamination by the SARS-Cov-2 virus in certain instances. Thus, ENT specialists are among the professionals who are most exposed to this infection. During the pandemic, insofar as an asymptomatic patient may be infected and contagious, the same precautions must be employed whether the patient is ill with, suspected of having, or without any clinical evidence of COVID-19 infection. According to the scientific data available, the examinations and procedures potentially exposing to projections/aerosolizations of organic material of human origin are considered to be at risk of staff contamination. For ENT examinations and procedures without exposure to such projections/aerosolizations, the professional is advised to a long sleeve clean outfit, a surgical mask and gloves in case of contact with the patient's mucosa. ENT examinations and procedures with exposure to these projections/aerosolizations require the so-called "airborne", "contact", and "droplets" additional precautions: FFP2/N95 respiratory protection device, eye protection, disposable headwear and long sleeve overgown.

Binding of a Glycera convoluta neurotoxin to cholinergic nerve terminal plasma membranes.

The crude extract of venom glands of the polychaete annelid Glycera convoluta triggers a large Ca2+-dependent acetylcholine release from both frog motor nerve terminals and Torpedo electric organ synaptosomes. This extract was partially purified by Concanavalin A affinity chromatography. The biological activity was correlated in both preparations to a 300,000-dalton band, as shown by gel electrophoresis. This confirmed previous determinations obtained with chromatographic methods. This glycoprotein binds to presynaptic but not postsynaptic plasma membranes isolated from Torpedo electric organ. Pretreatment of intact synaptosomes by pronase abolished both the binding and the venom-induced acetylcholine release without impairing the high K+-induced acetylcholine release. Pretreatment of nerve terminal membranes by Concanavalin A similarly prevented the binding and the biological response. Binding to Torpedo membranes was still observed in the presence of EGTA. An antiserum directed to venom glycoproteins inhibited the neurotoxin so we could directly follow its binding to the presynaptic membrane. Glycera convoluta neurotoxin has to bind to a ectocellularly oriented protein of the presynaptic terminal to induce transmitter release.

Isolation of pure cholinergic nerve endings from Torpedo electric organ. Evaluation of their metabolic properties.

Pure cholinergic nerve endings (synaptosomes) were isolated from the electric organ of Torpedo by a rapid procedure. These synaptosomes are approximately 3 micron in diameter. They contain an occasional mitochondrion, numerous synaptic vesicles, and sometimes an active zone is observed. No postynaptic membrane attachment is found. This nerve ending fraction is extremely pure as shown by morphological controls and biochemical data. It is rich in choline acetyltransferase (450 nmol/h per mg protein) and acetylcholine (ACh) (130 nmol/mg protein). The isolated endings retain their cytoplasmic components and they synthesize ACh and are stable in vitro for several hours, as shown by biochemical measurements and morphological analysis.

Isolation of a presynaptic plasma membrane fraction from Torpedo cholinergic synaptosomes: evidence for a specific protein.

Synaptosomal plasma membranes were isolated from Torpedo cholinergic synaptosomes which had been purified as previously described or repurified by equilibrium centrifugation. The synaptosomal plasma membrane could be distinguished from postsynaptic membranes by the absence of postsynaptic specific markers (nicotinic AChR) and by its low intramembrane particle complement after freeze fracture. In addition, the presynaptic membrane fraction contained acetylcholinesterase. Gel electrophoresis permitted the identification of a major protein component of the presynaptic membrane fraction which had a molecular weight of 67,000. This protein was not found in postsynaptic membrane or synaptic vesicle fractions. Thus it appeared to be specific to the nerve terminal plasma membrane.

Large-scale purification of presynaptic plasma membranes from Torpedo marmorata electric organ.

The presynaptic plasma membrane (PSPM) of cholinergic nerve terminals was purified from Torpedo electric organ using a large-scale procedure. Up to 500 g of frozen electric organ were fractioned in a single run, leading to the isolation of greater than 100 mg of PSPM proteins. The purity of the fraction is similar to that of the synaptosomal plasma membrane obtained after subfractionation of Torpedo synaptosomes as judged by its membrane-bound acetylcholinesterase activity, the number of Glycera convoluta neurotoxin binding sites, and the binding of two monoclonal antibodies directed against PSPM. The specificity of these antibodies for the PSPM is demonstrated by immunofluorescence microscopy.