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41.
An acromegalic patient with galactorrhea was treated with an ergot alkaloid, 2-Br-alpha-ergocryptine (CB-154). Serum prolactin decreased rapidly to normal level by CB-154 and the complete cessation of galactorrhea was noted. The inhibitory effect of CB-154 On growth hormone (GH) release was also noted, but slight. The mechanism of inhibitory action of CB-154 on both prolactin and GH secretion was discussed in connection with the experimental model of pituitary tumors, in which both hormones were produced by a single type of tumor cells. The discontinuation of CB-154 treatment was associated with the return of both prolactin and GH levels to the initial high values with resumption of galactorrhea. 相似文献
42.
1. Analysis of degradation processes of bovine fibrinogen by bovine plasmin using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a study on the mode of changes of the properties related to clotting of digestion products as a function of time were performed. Gross features and patterns very similar to those which had been reported with human fibrinogen-plasmin systems were obtained. 2. Based on the molecular size of the degradation products and the mode of appearance and disappearance of the degradation products, the processes could tentatively be divided into three stages: stage 1, where fibrinogen (mol. wt 370 000) was degraded to produce fragments X1 (330 000) and X2 (290 000); stage 2, fragment X2 was degraded with appearance of Y (210 000) and D1 (140 000); stage 3, appearance of fragments D1, D2 (110 000), and D3 (100 000) sequentially and E (68 000) with concomitant disappearance of Y. 3. A microseparation method, which is a combination of dansylation and sodium dodecylsulfate-polyacrylamide gel electrophoresis, was devised to analyze the events of stage 1 in detail, and a molecular model for the process was proposed. 4. The plasmic degradation processes of bovine non-cross-linked fibrins in solution and in gel form were compared with that of fibrinogen and it was found that the state of the substrates, fibrins, could cause differences in the degradation patterns. With the former substrate, essentially the same sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns as those with fibrinogen were obtained. With the latter substrate, however, a distinct difference in the mode of degradation of beta chains was observed. 相似文献
43.
The dose-frequency relationship for each of 2 types of lethal mutations, fractional- and whole-lethal, was obtained using X-rays on Drosophila melanogaster. The results show that fractional-lethal mutations are induced by X-rays, and also that the proportion of fractional-lethal mutations in the total of mutations tends to decrease with increasing doses, namely, 61% at 0 R, 47% at 500 R, 37% at 1000 R and 20% at 2000 R. The same tendency is observed with visible mutations.In order to consider the problems related to the above results, the relationship between the true frequency and the observed frequency of the induced lethal mutations is discussed, taking into consideration the existence of the ontensible whole-lethal and the ontensible normal. 相似文献
44.
Effects of sodium, potassium and chloride ions on the membrane potential of Valonia aegagropila 总被引:1,自引:0,他引:1
Changes of the resting potential of Valonia cell in sea wateragainst a 10-fold increase of the external concentrations ofK$, Na$ and Cl were 1±1, 6.2±0.1 and 38.9±4mV, respectively. The potassium conductance was smaller than7 µ/cm2, while the Na and Cl conductances were 45 and281 µ/cm2, respectively, in normal sea water. The positivevacuolar potential could be explained by these ionic conductances.On the other hand, the membrane became more sensitive to K$,if the cell was incubated for about 30 min in K-rich (100 mM)sea water. It is worth noting, however, that the membrane conductancewas lower in the K-rich sea water than in the normal sea water. (Received October 7, 1974; ) 相似文献
45.
46.
Cloning of human muscle phosphofructokinase cDNA 总被引:7,自引:0,他引:7
Three overlapping cDNA clones for human muscle phosphofructokinase (HMPFK) covering the complete coding sequence were isolated. The sequence included a poly(A) tail, a 399 bp 3'-untranslated region, a 2337 bp coding region for 779 amino acid residues and a part of the 5'-untranslated region. Homologies between HMPFK and rabbit muscle phosphofructokinase (RMPFK) were 96% of the amino acids and 89% of the nucleotides in the coding region. Like RMPFK, HMPFK also possessed the internal homology between C- and N-halves in its primary structure. Cloning of HMPFK cDNA will help to identify the molecular defect in patients with glycogenosis type VII (HMPFK deficiency). 相似文献
47.
James R. P. Worth Shota Sakaguchi Nobuyuki Tanaka Michimasa Yamasaki Yuji Isagi 《Biological journal of the Linnean Society. Linnean Society of London》2013,108(2):263-277
Sciadopitys verticillata is amongst the most relictual of all plants, being the last living member of an ancient conifer lineage, the Sciadopityaceae, and is distributed in small and disjunct populations in high rainfall regions of Japan. Although mega‐fossils indicate the persistence of the species within Japan through the Pleistocene glacial–interglacial cycles, how the species withstood the colder and drier climates of the glacials is not well known. The present study utilized phylogeography and palaeodistribution modelling to test whether the species survived within pollen‐based coastal temperate forest glacial refugia or within previously unidentified refugia close to its current range. Sixteen chloroplast haplotypes were found that displayed significant geographical structuring. Unexpectedly, northern populations in central Honshu most distant from coastal refugia had the highest chloroplast diversity and were differentiated from the south, a legacy of glacial populations possibly in inland river valleys close to its current northern range. By contrast, populations near putative coastal refugia in southern Japan, harboured the lower chloroplast diversity and were dominated by a single haplotype. Fragment size polymorphism at a highly variable and homoplasious mononucleotide repeat region in the trnT‐trnL intergenic spacer reinforced the contrasting patterns of diversity observed between northern and southern populations. The divergent histories of northern and southern populations revealed in the present study will inform the management of this globally significant conifer. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 263–277. 相似文献
48.
Synaptic vesicle membrane fusion complex: action of clostridial neurotoxins on assembly. 总被引:25,自引:7,他引:25 下载免费PDF全文
T Hayashi H McMahon S Yamasaki T Binz Y Hata T C Südhof H Niemann 《The EMBO journal》1994,13(21):5051-5061
Clostridial neurotoxins inhibit neurotransmitter release by selective and specific intracellular proteolysis of synaptobrevin/VAMP, synaptosomal-associated protein of 25 kDa (SNAP-25) or syntaxin. Here we show that in binary reactions synaptobrevin binds weakly to both SNAP-25 and syntaxin, and SNAP-25 binds to syntaxin. In the presence of all three components, a dramatic increase in the interaction strengths occurs and a stable sodium dodecyl sulfate-resistant complex forms. Mapping of the interacting sequences reveals that complex formation correlates with the presence of predicted alpha-helical structures, suggesting that membrane fusion involves intermolecular interactions via coiled-coil structures. Most toxins only attack the free, and not the complexed, proteins, and proteolysis of the proteins by different clostridial neurotoxins has distinct inhibitory effects on the formation of synaptobrevin-syntaxin-SNAP-25 complexes. Our data suggest that synaptobrevin, syntaxin and SNAP-25 associate into a unique stable complex that functions in synaptic vesicle exocytosis. 相似文献
49.
Sato M Sano H Iwaki D Kudo K Konishi M Takahashi H Takahashi T Imaizumi H Asai Y Kuroki Y 《Journal of immunology (Baltimore, Md. : 1950)》2003,171(1):417-425
The lung collectin surfactant protein A (SP-A) has been implicated in the regulation of pulmonary host defense and inflammation. Zymosan induces proinflammatory cytokines in immune cells. Toll-like receptor (TLR)2 has been shown to be involved in zymosan-induced signaling. We first investigated the interaction of TLR2 with zymosan. Zymosan cosedimented the soluble form of rTLR2 possessing the putative extracellular domain (sTLR2). sTLR2 directly bound to zymosan with an apparent binding constant of 48 nM. We next examined whether SP-A modulated zymosan-induced cellular responses. SP-A significantly attenuated zymosan-induced TNF-alpha secretion in RAW264.7 cells and alveolar macrophages in a concentration-dependent manner. Although zymosan failed to cosediment SP-A, SP-A significantly reduced zymosan-elicited NF-kappaB activation in TLR2-transfected human embryonic kidney 293 cells. Because we have shown that SP-A binds to sTLR2, we also examined whether SP-A affected the binding of sTLR2 to zymosan. SP-A significantly attenuated the direct binding of sTLR2 to zymosan in a concentration-dependent fashion. From these results, we conclude that 1) TLR2 directly binds zymosan, 2) SP-A can alter zymosan-TLR2 interaction, and 3) SP-A down-regulates TLR2-mediated signaling and TNF-alpha secretion stimulated by zymosan. This study supports an important role of SP-A in controlling pulmonary inflammation caused by microbial pathogens. 相似文献
50.
Nishimoto E Yamashita S Yamasaki N Imoto T 《Bioscience, biotechnology, and biochemistry》1999,63(2):329-336
The fluorescence spectral distributions of four tryptophan residues of hen egg-white lysozyme were analyzed using time-resolved and quenching-resolved fluorescence spectroscopy. Trp62 and Trp108 gave the fluorescence maxima at 352 nm and 342 nm, respectively. The fluorescence of Trp28 and Trp111 occurred only at 300-360 nm and they were observed as an unresolved emission band with a maximum and shoulder at 320 nm and 330 nm. The fluorescence quenching and decay parameters of each tryptophan residue reconfirmed that Trp62 was fully exposed to the solvent but Trp108 was sealed in the cage of the peptide chains and furthermore showed that Trp28 and Trp111 are under the influence of the larger fluctuational motion at the hydrophobic matrix box. The fluorescence responses of each tryptophan residue to the lysozyme-ligand interaction suggested that the internal fluctuation was reduced by the binding of ligand to give a distorted conformation to the hydrophobic matrix box region. 相似文献