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31.
Giovanni Romeo 《Human genetics》1977,39(3):261-276
Summary In four of the five autosomal dominant porphyrias four different partial enzymatic defects of the porphyrin biosynthetic pathway have been discovered in the last few years. With the exception of protoporphyria, the residual enzymatic activity in carriers of these defects is approximately equal to 50% of that found in controls. In each case the pattern of excretion of porphyrin and/or porphyrin precursors reflects the site of the partial metabolic block. There are indications, at least in intermittent acute porphyria, that the degree of penetrance of the disorder varies according to the level of phenotypic expression, being highest for the enzyme deficiency, lower for the excretion of precursors and lowest for the clinical symptoms. It is proposed that environmental factors, and probably also gene interaction, are the cause of the different degrees of penetrance.On leave from the University of Naples, Italy 相似文献
32.
Stimulus-induced maturation of probactenecins, precursors of neutrophil antimicrobial polypeptides 总被引:12,自引:0,他引:12
M Zanetti L Litteri G Griffiths R Gennaro D Romeo 《Journal of immunology (Baltimore, Md. : 1950)》1991,146(12):4295-4300
The antimicrobial polypeptides Bac7 and Bac5 (bactenecins) are stored in the large granules of bovine neutrophils as precursor forms, or probactenecins. Maturation of probactenecins has been investigated by studying the effects of stimulus-induced degranulation on this process. Stimulation of neutrophils with PMA, which is a secretagogue for specific and large granules but not for azurophils, induces a substantial discharge of uncleaved probactenecins in the extracellular medium, as revealed by Western blot analysis. When neutrophils are exposed to opsonized bacteria in the presence of cytochalasin B, resulting in exocytosis of the content of azurophils in addition to that of specific and large granules, probactenecins are secreted and rapidly converted into the corresponding mature antimicrobial peptides. Such a conversion is prevented if serine proteases, stored in the azurophils, are inhibited by pretreatment of neutrophils with PMSF. Phagocytosis, while causing a rapid discharge of the contents of azurophil and of the large granules into phagocytic vacuoles, as indicated by immunogold electron microscopy, also induces cleavage of probactenecins into mature peptides, as revealed by Western blot analysis. We conclude that the final processing of the storage forms of bactenecins arises from their interaction with the serine protease(s) of azurophils during bacteria-induced degranulation of neutrophils. 相似文献
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Severe and even fatal hemorrhage may be caused by bleeding through the interstices of a fabric graft. Improved fabrication of grafts with appropriate porosity for the conditions encountered has provided better hemostasis. Yet in some situations, bleeding through the fabric still presents a problem. A method of preclotting with autologous platelet rich plasma (PRP) and autoclaving is described. Gross and microscopic studies along with clinical applications confirm the effectiveness of the technique. 相似文献
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ATPase activity and phosphorylation by [γ-32P] ATP of isolated plasma membrane of alveolar macorphages are stimulated in a parallel fashion by physiologic concentrations of Ca2+, with half-maximal activating effect of this ion at (3–7) × 10?7 M. For various membrane preparations, a direct proportionality exists between Ca2+-dependent ATPase activity and amount of 32P incorporated. Labeling of membrane attains the steady-state level by 10 sec at 0°C, and is rapidly reversed by adenosine diphosphate (ADP). K+ decreases the amount of membrane-bound 32P, mainly by enhancing the rate of dephosphorylation of the 32P-intermediate. Hydroxylamine causes a release of about 90% of 32P bound to the membrane, thus indicating that the 32P-intermediate contains an acyl-phosphate bond. When the labeled plasma membrane is solubilized and electrophoresed on acrylamide gels in the presence of sodium dodecyl sulphate, the radioactivity appears to be largely associated with a single protein fraction of 132,500 ± 2,000 apparent molecular weight. These features of the macrophage Ca2+-ATPase suggest that the enzyme activity might be part of a surface-localized Ca2+-extrusion system, participating in the regulation of Ca2+-dependent activities of the macrophage. 相似文献
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Rabbit alveolar macrophages exposed to the ionophore A23187 in the presence of extracellular Ca2+ take up about 12 nmoles of Ca2+/1 × 106 cells. This uptake induces a slight, but significant, extracellular release of granule enzymes, β-glucuronidase and lysozyme, but not of the cytoplasmic marker, lactate dehydrogenase. If either EGTA is added to the medium or Mg2+ replaces Ca2+ no stimulation of secretion is observed. If the energy supply is decreased by treating the macrophages with mitochondrial inhibitors such as oligomycin, cyanide, or rotenone and antimycin, Ca2+-dependent secretion is potentiated several fold. Selective release of granule enzymes from macrophages exposed to A23187 and Ca2+ is also stimulated by cytochalasin B (CB). 相似文献
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cis-4-Hydroxypipecolic acid and 2,4-cis-4,5-trans-4,5-dihydroxypipecolic acid were isolated from leaves of Calliandra pittieri. A system for resolving the eight imino acids isolated from Calliandra is described. 相似文献