[Activity of diverse growth-phase E. coli ribosomes in protein biosynthesis in cell-free system].
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Biomedical subjects
Publications and source records attributed to S Michel.
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Prostate-specific antigen (PSA), the main marker for prostate cancer (PCa), is released from the prostate into the blood stream at nanogram level and may increase in PCa and nonmalignant disease such as benign prostate hyperplasia (BPH). More recently, advantage was taken of PSA's ability to bind to protease inhibitors in serum in order to improve discrimination between PCa and BPH, using the free PSA to total PSA ratio. The understanding of this phenomenon at molecular level, which is still unknown, may promise new improvements in the field of diagnostics. For this purpose, we determined the pattern of PSA forms in PCa and BPH sera, using the high resolving power of two-dimensional electrophoresis (2-DE) in conjunction with the high sensitivity of chemiluminescence detection. Serum PSA differs drastically from seminal PSA: apart from complexed forms, serum PSA shows few cleaved forms. Moreover, 2-DE patterns from PCa are relatively homogeneous, whereas patterns from BPH may in some cases present a higher proportion of cleaved forms and in other cases present slightly more basic spots. We therefore demonstrated, for the first time, that an increase in the free to total PSA ratio in BPH cases may be due to cleaved PSA forms (which are enzymatically inactive and unable to bind inhibitors), or possibly related to basic free PSA, which may represent the zymogen forms.
Prostate-specific antigen (PSA), a 237-amino acid glycoprotein, encoded by the hKLK3 gene, is widely used as a serum marker for the diagnosis and management of prostate cancer. We report here the localization of a conformational epitope recognized by the anti-total PSA monoclonal antibody (mAb) 11E5C6, by proteolytic degradation of mAb-bound antigen followed by mass spectrometric analyses of the peptides generated. These two technologies, combined with molecular display, allowed the identification of amino acid residues contained within three different peptides distant on the PSA sequence, but close in the PSA three-dimensional structure, that may be part of the mAb 11E5C6 epitope. The last four C-terminal amino acid residues are included in this epitope, as well as certain other C-terminal residues between Y225 and T232. The involvement of the PSA C-terminal end in the mAb 11E5C6 epitope was confirmed by western blotting experiments with the recombinant protein proPSA-RP1, resulting from the cloning of an alternative transcript of the hKLK3 gene, in which the PSA C-terminal end was deleted and replaced by another sequence. Although the anti-total PSA mAb 5D5A5 used as a control bound proPSA-RP1, mAb 11E5C6 did not. The requirement of the C-terminal end for the recognition by mAb 11E5C6 may be useful for the discrimination of PSA-related forms.
Xenograft rejection is associated with vascular injury resulting at least in part from platelet activation, and rejected xenografts invariably demonstrate intravascular thrombosis. Assuming that complement activation is a major determinant of humoral immune reactions bringing about platelet-endothelial cell interactions, we tested the effects of the specific platelet glycoprotein IIb/IIIa inhibitor tirofiban in combination with the human decay accelerating factor (hDAF) transgene on hyperacute rejection of pig hearts. Four groups were studied in a working heart-perfusion model. Pig hearts transgenic for hDAF and nontransgenic pig hearts were perfused with human blood containing tirofiban or with unmodified human blood. Cardiac output, stroke work index, and creatine phosphokinases were measured for the evaluation of the extent of myocardial damage. Consumption of complement components was determined. Endothelial deposition of fibrin and intravascular thrombosis were evaluated. Tirofiban improved cardiac output and stroke work index of nontransgenic pig hearts and was able to further increase hemodynamic function of hDAF transgenic pig hearts. Low levels of creatine phosphokinases also revealed a cardioprotective effect of tirofiban. However, a further extension of the survival of hDAF transgenic pig hearts could not be achieved, although tirofiban prolonged beating time of nontransgenic pig hearts. Tirofiban was able to reduce the consumption of complement components independently of hDAF. Intravascular evidence of fibrin and thrombosis tended to be particularly reduced by the combination of tirofiban and hDAF. Thus, the application of tirofiban together with hDAF improves the performance of pig hearts by reducing myocardial damage and intravascular thrombosis.
Human peripheral blood lymphocytes are one of the most radiosensitive mammalian cells. We tested whether this radiosensitivity was associated with the persistance of unrepaired DNA damage in gamma-irradiated lymphocytes. Repair was determined by measuring the loss and recovery of DNA supercoiling when nucleoids are centrifuged in the presence of increasing amounts of ethidium bromide. Results show a limited repair capacity in resting human lymphocytes after gamma-irradiation.
When mammalian cells are incubated with an uncoupler of oxidative phosphorylation prior to and during X-irradiation, the survival and the mutation frequency are markedly increased. This process requires protein synthesis and is inhibited when the cells are plated in the presence of a protease inhibitor (antipain or leupeptin). These results suggest the existence of an error-prone DNA repair process in X-irradiated mammalian cells.
We present a 2-year-old boy with a red, cutaneous-subcutaneous, nodule on the right elbow and a 2.5 year-old girl with an red-brown, indurated plaque on the left knee. Colour-coded doppler sonography of the boy's lesion showed vascular structures. A biopsy established the diagnosis of tufted angioma in both patients. Tufted angioma is clinically characterized by slowly spreading erythematous macules and plaques preferentially located on the upper trunk and neck in children. It is a benign tumor, malignant transformation has not been reported. The case history, clinical and histological findings contribute to the diagnosis. Tufted angioma has to be distinguished from Kaposi's sarcoma, angiosarcoma, hemangioma of infancy, sometimes bacillary angiomatosis and other cutaneous capillary malformations. Treatment of tufted angioma is difficult, various modalities like glucocorticosteroids, Interferon-alpha, flashlamp-pumped pulsed dye laser, excision and spontaneous regression have been described with varying results.
The availability of fetal cells from the maternal peripheral blood opens up the possibility for a noninvasive prenatal diagnosis. Until now this prospect has been hampered by the fact that there are no highly specific antibodies to fetal cells. In the present study, four as yet untested monoclonal antibodies - 2G5, 3F9, EPO-R and Flk1 - were analyzed in view of their effectiveness to stain fetal nucleated cells. Therefore, 20 ml of peripheral blood from 40 women carrying a male fetus were collected in the 16th to 28th weeks of pregnancy. Mononucleated cells, enriched by density gradient, were stained with one of the four antibodies and isolated with magnetic cell sorting. Subsequently, fluorescence in situ hybridization with chromosome X and Y centromere probes was performed which allowed us to analyze the maternal or fetal origin of the enriched cells. For evaluation, 500 nuclei per case were examined. The antibody 3F9 detected 0.2 cells on average (n = 5), 2G5 1.2 (n = 11), EPO-R 1.6 (n = 10) and Flk1 1.8 cells (n = 8) with fetal specific Y-positive hybridization signals. The antibody against CD71 (n = 6) used as control gave no Y-specific signals. Considering these results, the tested antibodies, especially Flk1, appear to be more successful in detecting fetal cells than the commonly used CD71 antibody.
The alkaloids chelerythrine, norchelerythrine, oxyavicine, canthine-6-one, 4,5-dihydrocanthin-6-one, and gamma-fagarine were isolated from Zanthoxylum dimorphophyllum bark, together with two coumarins, scoparone and dimoxylin. This latter is a novel compound whose structure was elucidated on the basis of its spectral data.
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The prevalence of obesity has increased over the past three decades, in children as well as in adults. When obesity develops in the childhood years, excess adiposity generally continues into adult years, and adult obesity with childhood onset is frequently more severe. The health consequences of obesity in adults are well established, including greater rates of hypertension, non-insulin dependent diabetes mellitus, and heart disease. This paper will discuss the risk factors for these adult disorders that are detectable in obese children. Compared to normal weight children, obese children have higher blood pressure, higher plasma insulin levels, and a more atherogenic lipid pattern. Thus, the characteristic features of Syndrome X, or the insulin resistant syndrome, can be detected in obese children and adolescents. The vascular consequences of exposure to these metabolic risk factors beginning in childhood have yet to be completely determined. However, it is very likely that childhood obesity does contribute significantly to cardiovascular disease. For these reasons, greater efforts should be mounted to reduce the currently rising rates.