Elevation of plasma thioredoxin levels in HIV-infected individuals

Thioredoxin (Trx), a ubiquitous protein intimately involvedin redox and protein disulfide reductions, has been shown tobe released from cells and to have cytokine-like activities.In addition, Trx has been implicated in the redox regulationof immunological responses and shown to be deficient in tissuesfrom AIDS patients. In studies presented here, plasma Trx levelswere measured by ELISA in plasma samples from HIV-infected individuals(n = 136) and HIV-negative controls (n = 47). To account forthe release of Trx into plasma due to hemolysis, the Trx measurementswere corrected according to the level of hemoglobin in the plasmasample. Data presented show that, in contrast to tissue Trxlevels, corrected plasma Trx levels are significantly higherin HIV-infected individuals than in controls (P < 0.0001).Furthermore, {small tilde}25% of the HIV-infected individualsstudied have plasma Trx levels greater than the highest levelfound in controls (37 ng/ml). Detailed multiparameter FACS analysisof peripheral blood mononuclear cells (PBMC) from the infectedindividuals demonstrates that those with higher plasma Trx levels(37 ng/ml or greater) tend to have lower overall CD4 counts.In addition, increases in plasma Trx levels correlate with decreasesin monochlorobimane staining (indicative of lower intracellularglutathione levels in PBMC) and with changes in surface antigenexpression (CD62L, CD38 and CD20) that occur in the later stagesof HIV infection. These correlations suggest that elevationof plasma Trx levels may be an important component of advancedHIV disease, perhaps related to the oxidative stress that oftenoccurs at this stage.     

Discordant repeat size and phenotype in Kennedy syndrome

Previous reports in the literature have described correlation of increasing repeat length with severity of the phenotype, in Kennedy syndrome. We describe male siblings with different repeat lengths, with lack of expression of the phenotype in the sibling with the longer repeat length. The phenotype was identical to motor neurone disease. There is variability of expression in Kennedy syndrome and repeat length even in siblings cannot be taken as a conclusive indicator of severity. CAG repeat length cannot be used to predict the natural history of Kennedy disease. The diagnosis of Kennedy syndrome should be considered in male patients presenting with atypical motor neurone disease.     

Uroscopy in the 21st century: high-field NMR spectroscopy

From the experiments described, it can be seen that there are different research approaches that can be taken and these are summarized in Table 1. Whereas much scientific research is principally hypothesis led, there remains, nevertheless, an important place for exploratory research. High resolution NMR can measure, directly and simultaneously, a wide range of endogenous metabolites in biological fluids and has the unique capability of providing structural information on the metabolites detected. It has proved to be a powerful research tool with which to study inherited metabolic diseases, renal disease, drug metabolism, and toxicity, and can be used to monitor the effects of drug therapy. For instance, by using a library of experimental toxins one can map the metabolic profile of site-specific nephron injury. With this approach in man one could eventually take an unknown disease such as Balkan nephropathy and predict the initial site of tubular injury, the mode of injury and therefore the kind of toxin capable of producing that injury. NMR spectroscopic techniques are still advancing rapidly, with ever increasing sensitivity and sophistication of NMR pulse sequences to enhance structural elucidation in complex mixtures. Given the advances in directly coupled HPLC-NMR and even HPLC-NMR-mass spectroscopy it is likely that these technologies in conjunction with pattern recognition will make major contribution to our understanding of renal processes and provide new diagnostic insights in the 21st century.      

Activation of guinea pig eosinophil respiratory burst by leukotriene B4: role of protein kinase C

Leukotriene B4 (LTB4) and the protein kinase C activator, 4-beta-phorbol dibutyrate (PDBu), both induced a pronounced and concentration-dependent stimulation of hydrogen peroxide (H2O2) generation by purified guinea pig peritoneal eosinophils in the concentration range 1 nM-1 microM. The LTB4 response was inhibited competitively by the specific LTB4 receptor antagonist, U-75302, with a KB of 25 nM, while the concentration-response curves for both stimuli were shifted rightwards (3.8-fold and 2.8-fold for LTB4 and PDBu, respectively) by the competitive protein kinase C inhibitor, 1-O-hexadecyl-2-O-methylglycerol at a concentration of 300 microM. LTB4 appears, therefore, to induce respiratory burst in eosinophils via a receptor-mediated mechanism involving protein kinase C.     

Localization of a gene for otosclerosis to chromosome 15q25-q26

Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.      

X-linked liver glycogenosis type II (XLG II) is caused by mutations in PHKA2, the gene encoding the liver alpha subunit of phosphorylase kinase

X-linked liver glycogenosis type II (XLG II) is a recently described X- linked liver glycogen storage disease, mainly characterized by enlarged liver and growth retardation. These clinical symptoms are very similar to those of XLG I. In contrast to XLG I patients, however, XLG II patients do not show an in vitro enzymatic deficiency of phosphorylase kinase (PHK). Recently, mutations were identified in the gene encoding the liver alpha subunit of PHK (PHKA2) in XLG I patients. We have now studied the PHKA2 gene of four unrelated XLG II patients and identified four different mutations in the open reading frame, including a deletion of three nucleotides, an insertion of six nucleotides and two missense mutations. These results indicate that XLG II is due to mutations in PHKA2. In contrast to XLG I, XLG II is caused by mutations that lead to minor structural abnormalities in the primary structure of the liver alpha subunit of PHK. These mutations are found in a conserved RXX(X)T motif, resembling known phosphorylation sites that might be involved in the regulation of PHK. These findings might explain why the in vitro PHK enzymatic activity is not deficient in XLG II, whereas it is in XLG I.