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41.
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Cultured adult cardiac myocytes were exposed to anoxia under substrate-free conditions. When compared to the metabolic changes in the oxygen deficient organ, those in the anoxic cell culture proceed in a similar, yet prolonged manner. Release of cytosolic enzymes starts with minor energetic disturbances and proceeds in close correlation to the actual ATP decay. Below 2 μmol. ATP/gWW, an increasing number of cells becomes irreversibly damaged, but above, 30 min reoxygenation leads to extensive recovery of the whole preparation. The results indicate that leakage of cytosolic enzymes during the early stage of anoxia is due to a gradual protein release from the individual cells, related to reversible membrane alterations. 相似文献
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Three bovine serum albumin-specific Lyt-2+ T suppressor (Ts) cell clones from CBA/J mice have been analyzed with regard to expression of L3T4 molecules. All three Ts-cell clones can be stained with monoclonal antibodies (mAb) to L3T4. Tested for the two clones restricted to recognition of Ek determinants, antigen-specific proliferation on antigen-presenting cells, but not the proliferation induced by conditioned medium can be inhibited by L314-specific mAb. In a similar way, Ts-cell cytolytic effector functions can be blocked by L3T4-specific mAb. Thus L3T4 structures seem to play a role in Ts-cell functions. Furthermore, the data support the view that L3T4 expression can be a property of class II-restricted T cells irrespective of their Lyt phenotype. 相似文献
45.
Cytokeratin expression in simple epithelia 总被引:10,自引:0,他引:10
Valentino Romano Mechthild Hatzfeld Thomas M. Magin Ralf Zimbelmann Werner W. Franke Gernot Maier Herwig Ponstingl 《Differentiation; research in biological diversity》1986,30(3):244-253
To study the regulation of the expression of cytokeratins characteristic of simple epithelia, i.e., human cytokeratins nos. 7, 8, 18, and 19, we prepared several cDNA clones coding for these proteins and their bovine counterparts. In the present study, we describe a cDNA clone of the mRNA coding for human cytokeratin no. 18, which was isolated from an expression library using the monoclonal antibody, KG 8.13. This clone (756 nucleotides, excluding the polyA portion), encodes approximately one-half of the mRNA (approximately 1.4 kb), identifies one mRNA band in Northern-hybridization blots, and specifically selects one mRNA species coding for cytokeratin no. 18, as demonstrated by translation in vitro. Comparison of the deduced amino acid sequence--confirmed by direct amino-acid-sequence analyses of some polypeptide fragments produced by cleavage with cyanogen bromide--indicated that cytokeratin no. 18 is a member of the acidic (type I) subfamily of cytokeratins. It has only limited sequence homologies in common with other intermediate-sized filament proteins, and these are essentially restricted to certain domains of the alpha-helical rod portion. The carboxyterminal tail sequence does not contain glycine-rich elements, thus distinguishing this cytokeratin from those acidic (type I) cytokeratins that are characterized by this feature. The similarities and differences between cytokeratin no. 18 and previously described epidermal cytokeratins are discussed in relation to the differences in the stability of the complexes which this cytokeratin forms with basic (type II) cytokeratins, as well as in relation to possible functional differences of cytokeratins in simple and stratified epithelia. 相似文献
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Summary Muscle fibers in rabbit extensor digitorum longus (EDL), tibialis anterior (TA) and soleus, and rat soleus, were examined immunohistochemically for two proteins of the sarcoplasmic reticulum, Ca-ATPase and calsequestrin (CaS). Fibers were typed with the histochemical reaction for actomyosin ATPase. In the rabbit EDL and TA, type I fibers clearly reacted less for Ca-ATPase and CaS than type II fibers, but the difference was less with CaS than with Ca-ATPase. Although the differences were relatively small, HB fibers consistently presented greater amounts of Ca-ATPase than IIA fibers. No types II subgroups could be recognized after incubation with anti-CaS. These findings confirm results from previous immunochemical measurements on whole muscles containing different proportions of IIA and IIB fibers (Leberer and Pette 1986). Type IIA and IIC in the rabbit and rat soleus reacted stronger for Ca-ATPase and for CaS than type I fibers. Small differences in Ca-ATPase, but not in CaS, were recognized within the type I fiber population. Therefore, type I fibers in the rabbit and rat soleus are not a homogeneous population. 相似文献
48.
Two H2 uptake-negative (Hup-) Rhizobium japonicum mutants were obtained that also lacked symbiotic N2 fixation (acetylene reduction) activity. One of the mutants formed green nodules and was deficient in heme. Hydrogen oxidation activity in this mutant could be restored by the addition of heme plus ATP to crude extracts. Bacteroid extracts from the other mutant strain lacked hydrogenase activity and activity for both of the nitrogenase component proteins. Hup+ revertants of the mutant strains regained both H2 uptake ability and nitrogenase activity. 相似文献
49.
Summary The chemical behaviour of the sodium form of ethylenediamine di(o-hydroxyphenylacetic acid), Na2EDDHA, in a calcareous soil column was studied. The results show loss about 2/3 of the synthetic chelate in the soil, possibly
due to microbial decomposition and/or fixation of EDDHA.
The application of Na2EDDHA caused an increase in the amount of water-soluble forms of certain elements in the following decreasing order: Fe, Cu,
Mn, Ni, Zn and Ca. The increase in the water-soluble forms of such elements is due possibly to the chelation of their insoluble
compounds in the soil.
The solubilization effect of Na2EDDHA and the subsequent movement of the elements in the soil solution resulted in a significant decrease in their amounts
in the exchangeable and acid-soluble forms in the soil.
In conclusion, the synthetic chelate of EDDHA underwent chemical reactions in the soil and caused changes in the ratio of
certain elements in the various chemical forms.
Sen. author, formerly graduate student at the University of Arizona, now Assistant Professor, University of Ain-Shams, Cairo,
Egypt. Jr. author, Vice Chancellor, University of Wisc.-Green Bay. 相似文献
50.