Antibodies to nucleic acids in myasthenia gravis.

An increased frequency of antibodies to native DNA, thymocytes, and striated muscle was found in patients with myasthenia gravis (MG). The prevalence of such antibodies lends considerable support to the concept of MG as an autoimmune disorder and militates in favor of major abnormalities in the thymic dependent immune system. There was no correlation between serum-blocking activity to acetylcholine receptor protein and antibodies to thymocytes.     

Alternative splicing of exon 14 determines nuclear or cytoplasmic localisation of fmr1 protein isoforms

Impaired expression of the FMR1 gene is responsible for the fragile X mental retardation syndrome. The FMR1 gene encodes a cytoplasmic protein with RNA-binding properties. Its complex alternative splicing leads to several isoforms, whose abundance and specific functions in the cell are not known. We have cloned in expression vectors, cDNAs corresponding to several isoforms. Western blot comparison of the pattern of endogenous FMR1 proteins with these transfected isoforms allowed the tentative identification of the major endogenous isoform as ISO 7 and of a minor band as an isoform lacking exon 14 sequences (ISO 6 or ISO 12), while some other isoforms (ISO 4, ISO 5) were not expressed at detectable levels. Surprisingly, in immunofluorescence studies, the transfected splice variants that exclude exon 14 sequences (and have alternate C-terminal regions) were shown to be nuclear. Such differential localisation was however not seen in subcellular fractionation studies. Analysis of various deletion mutants suggests the presence of a cytoplasmic retention domain encoded in exon 14 and of a nuclear association domain encoded within the first eight exons that appear however to lack a typical nuclear localisation signal.      

Prothrombin and factor V mutations in women with a history of thrombosis during pregnancy and the puerperium

BACKGROUND: Venous thromboembolism is a leading cause of morbidity and mortality during pregnancy and the puerperium. However, the role of mutations in the prothrombin and factor V genes and other thrombophilic abnormalities as risk factors for thromboembolism in women during pregnancy and the pueperium is not known. METHODS: In a study of 119 women with a history of venous thromboembolism during pregnancy and the puerperium and 233 age-matched normal women, we measured the activity of antithrombin, protein C, protein S, and lupus anticoagulant. We also performed genetic analyses to detect the G1691A mutation in the factor V gene (factor V Leiden), the G20210A mutation in the prothrombin gene, and the C677T mutation in the methylenetetrahydrofolate reductase gene. Blood samples were obtained at least three months post partum or after the cessation of lactation. RESULTS: Among the women with a history of venous thromboembolism, the prevalence of factor V Leiden was 43.7 percent, as compared with 7.7 percent among the normal women (relative risk of venous thromboembolism, 9.3; 95 percent confidence interval, 5.1 to 16.9); that of the G20210A prothrombin-gene mutation, 16.9 percent as compared with 1.3 percent (relative risk, 15.2; 95 percent confidence interval, 4.2 to 52.6); and that of both factor V Leiden and the G20210A prothrombin-gene mutation 9.3 percent as compared with 0 (estimated odds ratio, 107). Assuming an overall risk of 1 in 1500 pregnancies, the risk of thrombosis among carriers of factor V Leiden was 0.2 percent, among carriers of the G20210A prothrombin-gene mutation, 0.5 percent, and among carriers of both defects, 4.6 percent, as calculated in a multivariate analysis. CONCLUSIONS: The G20210A prothrombin-gene mutation and factor V Leiden individually are associated with an increased risk of venous thromboembolism during pregnancy and the puerperium, and the risk among women with both mutations is disproportionately higher than that among women with only one mutation.     

The development of four unselected 47,XYY boys

Four infants identified through neonatal screening programs are an unselected sample of 47,XYY boys. No consistent physical stigmata or medical disorders were identified. Three have increased height. All four demonstrated problems in motor and language development. Although their intelligence is within the average range, all four have language-related learning disorders requiring special education. Mild depression was apparent in all four, perhaps as a secondary result of their learning disorders. Some of the problems seen in the propositi are found in milder forms in other family members, leading to the hypothesis that their karyotype may heighten vulnerability to pre-existing familial conditions. Similarities between these findings and results from seven other study centers with a total of 42 47,XYY boys are noted. Parents of a prenatally diagnosed 47,XYY fetus seen in our center are informed that the extra Y chromosome represents a risk factor for these problems, but that environment remains a primary force in shaping their child's development.     

Antiarrhythmic effects of stirocainide in acute myocardial infarction

Ventricular arrhythmias, especially ventricular fibrillation, are assumed to be a main cause of sudden death during the first 24 h of acute myocardial infarction. Effective prophylaxis and acute suppression of these life-threatening rhythm disturbances are a major therapeutic problem. The present study was undertaken to investigate the efficacy of the new antiarrhythmic compound stirocainide (2-(1-benzylidene)cycloheptenimino-oxyethyl-diisopropylamine -2-butenedionate, Th 494) in suppressing "2nd phase arrhythmias" arising from large anteroseptal myocardial infarctions using a standardized experimental canine preparation. Our results demonstrate that "2nd phase arrhythmias"--i.e. frequent ventricular ectopics, tachycardias, salvos, and R-on-T phenomena--are reduced by 80-90% (sometimes even completely abolished) by stirocainide (dose: 4 mg/kg within 3 min, followed by 300 micrograms/kg X min over a 20-min period). The administration of the drug at the dose used does not produce severe cardiodepression, but intraventricular conduction time is significantly prolonged. Thus, Th 494 is a highly effective antiarrhythmic agent in acute myocardial infarction, and further experimental and clinical investigations on its antiarrhythmic and antifibrillatory properties may lead to beneficial therapeutic results.     

Application of validated mapping algorithms between generic PedsQL scores and utility values to individuals with sickle cell disease

Quality of Life Research - There is a paucity of empirically estimated health state utility (HSU) values to estimate health-related quality of life among individuals with sickle cell disease (SCD)....     

Platelet glycoprotein VI-dependent thrombus stabilization is essential for the intraportal engraftment of pancreatic islets

Platelet activation and thrombus formation have been implicated to be detrimental for intraportal pancreatic islet transplants. The platelet-specific collagen receptor glycoprotein VI (GPVI) plays a key role in thrombosis through cellular activation and the subsequent release of secondary mediators. In aggregometry and in a microfluidic dynamic assay system modeling flow in the portal vein, pancreatic islets promoted platelet aggregation and triggered thrombus formation, respectively. While platelet GPVI deficiency did not affect the initiation of these events, it was found to destabilize platelet aggregates and thrombi in this process. Interestingly, while no major difference was detected in early thrombus formation after intraportal islet transplantation, genetic GPVI deficiency or acute anti-GPVI treatment led to an inferior graft survival and function in both syngeneic mouse islet transplantation and xenogeneic human islet transplantation models. These results demonstrate that platelet GPVI signaling is indispensable in stable thrombus formation induced by pancreatic islets. GPVI deficiency resulted in thrombus destabilization and inferior islet engraftment indicating that thrombus formation is necessary for a successful intraportal islet transplantation in which platelets are active modulators.     

Characterization of human mononuclear cells using reduced pyridine nucleotide fluorescence and flow cytometry

Peripheral blood monocytes undergo an oxidative burst similar to that seen in neutrophils. The basis for this response appears to be an NAD(P)H oxidase that utilizes reduced NAD(P)H to form superoxide anion. We utilized the unique UV-stimulated fluorescence property of reduced pyridine nucleotides to analyze NAD(P)H utilization in monocytes. UV-stimulated fluorescence in mononuclear cell preparations indicated two populations of cells with the highly fluorescent cells having a Coulter volume consistent with that of monocytes. Dual laser analysis with monoclonal antibodies confirmed that these highly fluorescent cells are monocytes by showing them to be OKM1+, Leu DR+, and anti-monocyte 0.2+. Natural killer (NK) cells, as defined by Leu 7, were not found in this highly fluorescent population. Stimulation of mononuclear cells with phorbol myristate acetate caused a fluorescence loss indicative of NAD(P)H oxidation in monocytes but not in lymphocytes. Stimulation with suboptimal concentrations of PMA (1-5 ng/ml) resulted in a dose-dependent fluorescence loss in monocytes that occurred in an all-or-none fashion identical to the pattern observed in neutrophils. Simultaneous measurement of H2O2 production using dichlorofluorescein formation with NAD(P)H fluorescence indicates that oxidant production occurs in a graded manner. This method, then, provides a convenient way to study in single cells the metabolic events involved in depletion and replenishment of NAD(P)H during the oxidative burst and demonstrates an additional means by which to distinguish monocytes from lymphocytes using flow cytometry.     

Needle biopsy of renal allografts: comparison of two techniques

Two techniques for renal allograft biopsy were retrospectively evaluated to compare relative safety and efficacy. After ultrasound (US) localization of the kidney and biopsy with a hand-held 14-gauge cutting needle, an adequate specimen was obtained in 74 of 77 cases (96%). Major complications occurred in six of these 77 cases (8%). One hundred four biopsies were performed by using a smaller 18-gauge cutting needle with a spring-loaded biopsy "gun" and real-time US guidance. With this newer technique, specimens adequate for diagnosis were obtained in 99 biopsies (95%). There was a single major complication with this technique (1%). The 18-gauge needle with real-time US guidance yields comparably adequate specimens with a lower frequency of complications.