Lectins discriminate between pathogenic and nonpathogenic South American trypanosomes

Cell surface carbohydrates of Trypanosoma cruzi, Trypanosoma rangeli, and Trypanosoma conorhini were analyzed by a micro-agglutination assay employing 27 highly purified lectins and by binding assays using various 125I-labeled lectins. The following seven lectins discriminated between the trypanosomes: 1) tomato lectin (an N-acetyl-D-glucosamine-binding protein), both in purified form and as crude tomato juice; 2) Bauhinea purpurea and Sophora japonica lectins (both N-acetyl-D-galactosamine-binding proteins), which selectively agglutinated T. cruzi; 3) Vicia villosa (an N-acetyl-D-galactosamine-binding protein) which was specific for T. rangeli; 4) peanut lectin (a D-galactose-binding protein) both in purified form and as crude saline extract; and 5) Ulex europaeus and Lotus tetragonolobus (both L-fucose-binding proteins) lectins which reacted only with T. conorhini. Binding studies with 125I-labeled lectins were performed to find whether unagglutinated cells of the three different species of trypanosomes might have receptors for these lectins, in which case absence of agglutination could be due to a peculiar arrangement of the receptors. These assays essentially confirmed the agglutination experiments.     

Comparison of provocative tests for unexplained syncope: isoprenaline and glyceryl trinitrate for diagnosing vasovagal syncope.

AIMS: To compare the sensitivity, specificity and adverse event profile of glyceryl trinitrate head-up tilt with isoprenaline head-up tilt in the diagnosis of vasovagal syncope in patients with unexplained syncope and healthy controls. METHODS AND RESULTS: Forty-eight patients with unexplained syncope and negative passive head-up tilt at 70 degrees for 40 min, and 14 healthy controls underwent glyceryl trinitrate head-up tilt and isoprenaline head-up tilt (maximum dose 5 microg x min(-1)) one week apart in random order. Outcome measures were production of symptoms (syncope, pre-syncope) with development of hypotension. In those with negative passive head-up tilt, the sensitivity of glyceryl trinitrate for diagnosing vasovagal syncope was 48% and the specificity was 71%. Glyceryl trinitrate was well tolerated. Isoprenaline sensitivity was 21% with specificity 64%. Side-effects prevented completion of the test in 68%. Commonest adverse events were the development of hypertension or tachycardia and intolerable flushing or nausea. CONCLUSIONS: Glyceryl trinitrate head-up tilt is as effective as isoprenaline head-up tilt as a provocative agent for vasovagal syncope and has a lower incidence of adverse events.     

Cumulative inactivation of N-type CaV2.2 calcium channels modified by alternative splicing

The Ca(V)2 family of voltage-gated calcium channels, present in presynaptic nerve terminals, regulates exocytosis and synaptic transmission. Cumulative inactivation of these channels occurs during trains of action potentials, and this may control short-term dynamics at the synapse. Inactivation during brief, repetitive stimulation is primarily attributed to closed-state inactivation, and several factors modulate the susceptibility of voltage-gated calcium channels to this form of inactivation. We show that alternative splicing of an exon in a cytoplasmic region of the Ca(V)2.2 channel modulates its sensitivity to inactivation during trains of action potential waveforms. The presence of this exon, exon 18a, protects the Ca(V)2.2 channel from entry into closed-state inactivation specifically during short (10 ms to 3 s) and small depolarizations of the membrane potential (-60 mV to -50 mV). The reduced sensitivity to closed-state inactivation within this dynamic range likely underlies the differential responsiveness of Ca(V)2.2 splice isoforms to trains of action potential waveforms. Regulated alternative splicing of Ca(V)2.2 represents a possible mechanism for modulating short-term dynamics of synaptic efficacy in different regions of the nervous system.     

Detection of a recurring mutation in the human growth hormone-releasing hormone receptor gene

OBJECTIVE: Mutations in the gene encoding for the GH-releasing hormone receptor (GHRHR) have been recently described in patients with familial isolated GH deficiency (IGHD) type IB. To date, all reported mutations have been found in kindreds sharing common ancestors. The only exception is a T to A transversion which causes a substitution of histidine for leucine in codon 144 (L144H) and creates a DraIII restriction site. This mutation was described in two families with different ethnic background residing in two different continents (Europe and North America). DESIGN: We searched for GHRHR mutations in a new family with IGHD from a third continent (South America) and found the affected individuals to be homozygous for the same L144H change. We performed linkage analysis with intra- and para-genic polymorphisms to determine if the three families carrying the L144H allele are related. RESULTS: Linkage analysis studies demonstrated that one of the three families does not share the same para- and intragenic GHRHR polymorphisms with the other two. CONCLUSIONS: The L144H mutation has arisen at least twice and should be considered for initial genetic analysis in patients with familial IGHD in whom the a GHRHR mutation is suspected.     

Hemostatic gene polymorphisms and the prevalence of thrombotic complications in polycythemia vera and essential thrombocythemia.

Patients with polycythemia vera and essential thrombocythemia are at risk for thrombotic and bleeding complications. Currently, no diagnostic test can predict thrombohemorrhagic complications. In a prospective study of 86 patients with polycythemia vera (43 patients) or essential thrombocythemia (43 patients), we examined the possible role of polymorphisms of platelet adhesion receptors [glycoprotein (GP) Ibalpha, GPIa, GPIIIa) and clotting factor II (prothrombin's G20210A mutation) and clotting factor V (Leiden mutation) in determining the risk of thrombotic or bleeding complications. Except for an association between vasomotor symptoms and prothrombin mutation (P < 0.001), no significant correlation between polymorphism of clotting factors and thrombohemorrhagic complications was identified. When the entire patient cohort was considered, the polymorphisms of platelet adhesion receptors were not associated with the risk for thrombotic or bleeding complications. However, among patients with polycythemia vera, the presence of the PlA2 allele of GPIIIa was associated with an increased risk of arterial thrombosis. In view of previous studies linking the presence of the PlA2 allele of GPIIIa to a higher risk for coronary artery thrombosis, our data have physiologic relevance. However, they need to be confirmed in a larger study.     

ATP diphosphohydrolase in human platelets from patients with coronary arteries heart disease

ATP diphosphohydrolase is an enzyme described in platelets and may be related to the control of ADP-dependent platelet aggregation. Platelet aggregation in atherosclerotic coronary arteries, and the release of platelet-derived factors, play an important role in coronary artery disease syndromes. In this study, we determined the activity of ATP diphosphohydrolase in platelets from patients with chronic and acute coronary artery disease syndromes and healthy persons. The following groups were studied: healthy persons (group I), patients with chronic heart disease (group II) and acute heart disease (group III). Results did not demonstrate differences between the groups studied. The control group demonstrated a lower range of enzyme activity. The patients from groups II and III had ingested drugs with actions upon the cardiovascular system and the effect, in vitro, of these drugs upon the ATP diphosphohydrolase activity in human platelets was also investigated. The in vitro experiments demonstrated that 2.0 mM acetylsalicylic acid inhibited ATP hydrolysis by human platelets by approximately 55%. Significant correlation was observed between ADP hydrolysis and glucose blood levels in the control group and between ATP hydrolysis and triglycerides in the group II. These results contribute to our understanding of a possible relationship between ATP diphosphohydrolase and thrombogenesis.     

Efficacy of tramadol in treatment of chronic low back pain

OBJECTIVE: To evaluate the efficacy and safety of tramadol in the treatment of chronic low back pain. METHODS: A 3 phase trial: (1) a washout/screening phase; (2) a 3 week, open label, run-in phase; and (3) a 4 week, randomized, placebo controlled, double blind treatment phase. Three hundred eighty outpatients between 21 and 79 years with chronic low back pain with no or a distant history of back surgery enrolled in the open label phase and were treated with tramadol up to 400 mg/day. At the end of the open label phase, patients who tolerated tramadol and perceived benefit from it were randomized to continue treatment with tramadol or to convert to placebo in the double blind phase. Reasons for discontinuing from the open label phase included adverse events, 78 patients (20.5%); drug ineffective, 23 patients (6.1%); and other reasons, 25 patients (6.6%). Two hundred fifty-four patients entered the double blind phase, during which the daily dose was maintained within the range 200-400 mg tramadol or equivalent amount of placebo. The primary outcome measure in the double blind phase was the time to discontinuation due to inadequate pain relief. RESULTS: The distribution of time to therapeutic failure was significantly (p < or = 0.0001) different in the tramadol group compared to placebo. Kaplan-Meier estimate of the cumulative discontinuation rate due to therapeutic failure was 20.7% in the tramadol group and 51.3% in the placebo group. There were significantly lower (p < or = 0.0001) mean pain visual analog scores (10 cm scale) among tramadol patients (3.5 cm) compared to placebo patients (5.1 cm) at the final visit of the double blind phase. Tramadol patients scored significantly better on the McGill Pain Questionnaire (p = 0.0007) and the Roland Disability Questionnaire (p = 0.0001). Five of 127 tramadol treated patients and 6/127 placebo treated patients discontinued treatment during the double blind phase due to an adverse event. Commonly reported adverse events with tramadol included nausea, dizziness, somnolence, and headache. CONCLUSION: Among patients who tolerated it well, tramadol was effective for the treatment of chronic low back pain.     

Cost/efficacy ratio in the diagnosis of coronary disease. Bayes' analysis by computer: respective role of the exercise test, isotopic methods and coronarography

Between January 1983 and May 1984, 104 patients with no known cardiac pathology were referred by their cardiologist for diagnosis of chest pain. They all underwent coronary angiography which was used as the reference investigation and the following sequential Bayes' analysis was performed. The percentage probability of coronary artery disease was estimated from clinical date (age, sex, characteristics of the chest pain subdivided into 3 groups); an exercise ECG was performed in all cases (classified as positive, negative or non diagnostic); if the probability of coronary artery disease was greater than 95% (or less than 5%) after exercise stress testing the patients was diagnosed as having (or not having) coronary artery disease. If the probability was between 6 and 94% the patient underwent Thallium myocardial scintigraphy (Thallium dipyridamole; analysis on a colour television screen); the coronary risk probability before Thallium was that calculated after exercise stress testing. If after myocardial scintigraphy the coronary risk remained between 6 and 94%, an exercise angioscintigraphy was performed and interpreted in the same way. The clinical and complementary date was analysed on a mini-computer, the values of the sensitivity and specificity of the tests used for the calculation of the probability of coronary artery disease were those previously published by our group. Results: 31/88 (35%) of patients were classified in the 5% risk groups after exercise stress testing (24 coronary artery disease; 7 normals: no errors of classification). Fifty six out of the 88 patients (65%) were classified in the 5% risk group after myocardial scintigraphy (42 patients with coronary artery disease with 41 abnormal coronary angiographies and 14 normal patients, all of whom had normal coronary angiographies; this represents a 1.8% divergence of classification compared with coronary angiography). Angioscintigraphy only classified 3 of the remaining patients, one wrongly, and did not seem to be useful diagnostically as a third-line investigation after Thallium scintigraphy or as a second-line investigation instead of Thallium scintigraphy. This strategy is less costly than carrying out coronary angiography systematically in these patients: if diagnostic coronary angiography is performed alone in patients with a risk of 6 to 94% the cost is 4 800 FF vs 10 400 FF per patient; if coronary angiography is performed in all patients in whom coronary artery disease is possible or certain (all patients with a risk of over 5%), the cost is 8 400 FF vs 10 400 FF per patient, a saving of 20%.(ABSTRACT TRUNCATED AT 400 WORDS)