Polymorphisms of the tissue factor pathway inhibitor (TFPI) gene in patients with acute coronary syndromes and in healthy subjects : impact of the V264M substitution on plasma levels of TFPI.
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-Mutations of the gene encoding tissue factor pathway inhibitor (TFPI), an inhibitor of TF-induced activation of the coagulation cascade, were screened for in 130 patients and 142 healthy controls to determine whether these variants contribute to acute coronary syndromes or modify plasma TFPI levels. The following 3 new polymorphisms were identified: 384T-->C in exon IV, which does not change the corresponding amino acid (tyrosine 57); -33C-->T in intron 7 (the T/T, C/T, and C/C genotypes were found in approximately 50%, 40%, and 10% of subjects in both groups); and 874G-->A in exon IX (GTG-->ATG), which predicts a valine to methionine change (V264M) in the carboxy-terminus tail of TFPI. The V264M polymorphism was found in 9.2% of the cases and 4.9% of the controls; the associated odds ratio (OR) for acute coronary syndromes was 2.0 (95% confidence interval [CI], 0.7 to 5.1). The OR increased to 3.6 (95% CI, 0.8 to 15.7) and 3.2 (95% CI, 0.9 to 11.8) in nonsmokers and patients without other risk factors, respectively. The possible link between the V264M polymorphism and coronary heart disease was checked in a large case-control study of myocardial infarction (Etude Cas-Temoins de l'Infarctus du Myocarde [the ECTIM Study]). The results showed no link between the V264M polymorphism and coronary syndromes. Interestingly, however, 5 patients heterozygous for the V264M polymorphism had significantly lower plasma TFPI levels than did 13 patients with the most common genotype. Although our present results do not support an association between TFPI polymorphisms and acute coronary syndromes, the possibility that 1 of them, especially the exon IX polymorphism, is associated with subtypes of myocardial infarction or to evolutive particularities that were not assessed in this study, cannot be excluded and is currently being evaluated. (+info)
AJvW-2, an anti-vWF monoclonal antibody, inhibits enhanced platelet aggregation induced by high shear stress in platelet-rich plasma from patients with acute coronary syndromes.
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The platelet aggregation that is dependent on von Willebrand factor (vWF) is important in the thrombogenesis that occurs under conditions of high shear stress, eg, during acute coronary syndromes (ACSs). A monoclonal antibody, AJvW-2, directed against the A1 domain of human vWF specifically blocks the interaction between plasma vWF and platelet glycoprotein (GP) Ib. To evaluate the association between the vWF-GPIb interaction and the enhanced shear-induced platelet aggregation (SIPA) observed in ACSs, we tested the effect of this antibody on platelet aggregation. Platelet-rich plasma was prepared from the citrated blood of 12 patients with unstable angina (UAP) and 20 patients with acute myocardial infarction (AMI) who were admitted within 3 hours of the onset of cardiac symptoms and from 18 controls. We observed the following: (1) 1.7-fold higher plasma levels of vWF and ristocetin cofactor activity in UAP patients and (2) 2.8-fold higher levels in the AMI group than in controls. Using a cone-and-plate viscometer, we measured the mean value of SIPA under high-shear conditions (108 dyne/cm2) and found them to be 1.3-fold higher in the UAP group and 2.0-fold higher in the AMI group than in controls. The high SIPA in all groups was completely inhibited by 10 microgram/mL AJvW-2. Under low-shear conditions (12 dyne/cm2), platelet aggregation was increased only in the AMI group, but this was unaffected by AJvW-2. We observed a significant correlation in both ACS groups between high SIPA and the plasma vWF level or vWF larger multimers. These findings suggest that the vWF-GPIb interaction is important in coronary occlusion and that inhibition of this interaction (with the use of AJvW-2) may prevent further events in the coronary arteries. (+info)
CD40 ligand mutants responsible for X-linked hyper-IgM syndrome associate with wild type CD40 ligand.
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CD40 ligand (CD40L) is a 33-kDa type II membrane glycoprotein mainly expressed on activated CD4(+) T cells in trimeric form. When it is mutated, the clinical consequences are X-linked hyper-IgM syndrome (XHIM), a primary immunodeficiency disorder characterized by low levels of IgG, IgA, and elevated or normal levels of IgM. Mutated CD40L can no longer bind CD40 nor provide signals for B cells to proliferate and to switch from IgM to other immunoglobulin isotypes. When considering gene therapy for XHIM, it is important to address the possibility that the mutated CD40L associates with transduced wild type CD40L, and as a consequence, immune reconstitution is not attained. In this study, we demonstrate that the various mutated CD40L species we have identified in patients with XHIM, including both full-length and truncated mutants, associate with wild type CD40L on the cell surface of co-transfected COS cells. The association between wild type and mutated CD40L was also observed in CD4(+) T cell lines established from XHIM patients with leaky splice site mutations. The clinical phenotype of these patients suggests that this association between wild type and mutated CD40L species may result in less efficient cross-linking of CD40. (+info)
Germline mutations in the extracellular domains of the 55 kDa TNF receptor, TNFR1, define a family of dominantly inherited autoinflammatory syndromes.
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Autosomal dominant periodic fever syndromes are characterized by unexplained episodes of fever and severe localized inflammation. In seven affected families, we found six different missense mutations of the 55 kDa tumor necrosis factor receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds. Soluble plasma TNFR1 levels in patients were approximately half normal. Leukocytes bearing a C52F mutation showed increased membrane TNFR1 and reduced receptor cleavage following stimulation. We propose that the autoinflammatory phenotype results from impaired downregulation of membrane TNFR1 and diminished shedding of potentially antagonistic soluble receptor. TNFR1-associated periodic syndromes (TRAPS) establish an important class of mutations in TNF receptors. Detailed analysis of one such mutation suggests impaired cytokine receptor clearance as a novel mechanism of disease. (+info)
Defective CD95/APO-1/Fas signal complex formation in the human autoimmune lymphoproliferative syndrome, type Ia.
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Heterozygous mutations in the CD95 (APO-1/Fas) receptor occur in most individuals with autoimmune lymphoproliferative syndrome (ALPS) and dominantly interfere with apoptosis by an unknown mechanism. We show that local or global alterations in the structure of the cytoplasmic death domain from nine independent ALPS CD95 death-domain mutations result in a failure to bind the FADD/MORT1 signaling protein. Despite heterozygosity for the abnormal allele, lymphocytes from ALPS patients showed markedly decreased FADD association and a loss of caspase recruitment and activation after CD95 crosslinking. These data suggest that intracytoplasmic CD95 mutations in ALPS impair apoptosis chiefly by disrupting death-domain interactions with the signaling protein FADD/MORT1. (+info)
Abnormal prenatal sonographic findings in the posterior cranial fossa: a case of Joubert's syndrome.
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Joubert's syndrome is a well-documented but rare disorder characterized by a variable combination of central nervous system, respiratory, renal and eye anomalies. The most significant and constant neuropathological finding is partial or complete agenesis of the cerebellar vermis. The syndrome was first described by Joubert and colleagues as a familial agenesis of the cerebellar vermis and appears to be inherited as an autosomal recessive trait. A case of Joubert's syndrome is described in which second-trimester ultrasonography demonstrated abnormal findings in the fetal posterior fossa with associated renal abnormalities. However, postnatal sonography of the posterior fossa could not confirm the prenatal findings, and the diagnosis of Joubert's syndrome was only later established by computed tomography of the neonatal brain in the knowledge of the characteristic clinical picture. (+info)
Evaluation of a mutation screening strategy for sporadic cases of ATR-X syndrome.
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We report on the evaluation of a strategy for screening for XNP/ATR-X mutations in males with mental retardation and associated dysmorphology. Because nearly half of the mutations in this gene reported to date fall into a short 300 bp region of the transcript, we decided to focus in this region and to extend the mutation analysis to cases with a negative family history. This study includes 21 mentally retarded male patients selected because they had severe mental retardation and a typical facial appearance. The presence of haemoglobin H or urogenital abnormalities was not considered critical for inclusion in this study. We have identified six mutations which represents a mutation detection rate of 28%. This figure is high enough for us to propose this strategy as a valid first level of screening in a selected subset of males with mental retardation. This approach is simple, does not require RNA preparation, does not involve time consuming mutation detection methods, and can thus be applied to a large number of patients at a low cost in any given laboratory. (+info)
Syndromic management of sexually transmitted diseases: is it rational or scientific?
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Control of sexually transmitted diseases improves the reproductive and sexual health of afflicted individuals and lowers the community burden of HIV. Preventing STDs or their complications requires health education, condom promotion and effective case management. Clinical diagnosis is frequently incorrect while laboratory-confirmed aetiological diagnosis is expensive. In resource-poor countries which lack trained personnel and laboratory facilities, syndromic management remains a rational approach to STD care. Although the approach is simplistic in design, its successful implementation requires regular monitoring and evaluation of protocols as well as supervision and training of clinicians. (+info)