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71.
The skin and lymphoid organs of Mexican hairless dogs and their hairless offspring were examined histologically. The hairless dogs lacked most hairs except for sparse hairs on the head, tail and feet. The skin of newborn pups consisted of a thick epidermis with epidermal ingrowths forming the rudiments of hair follicles. In older dogs more than 2 months of age, however, the epidermis was thin and the ingrowths were few. Neither hair follicles nor skin glands were present. The hairy skin of the head and tail had hair follicles with sebaceous glands. Regarding the lymphoid organs, the newborn pups possessed a thymus like haired pups. But in the older dogs more than 2 months of age, the thymus was atrophied and the lymphocyte population was too sparse to demarcate the cortex and the medulla. Lymphocyte accumulation in older dogs was also poor in the spleen and mesenteric lymph nodes. The present findings indicate that the hairlessness of the Mexican hairless dogs and their descendants is accompanied by early atrophy of the thymus after birth, and is followed by poor accumulation of lymphocytes in the thymus-dependent area of the spleen and the mesenteric lymph nodes. The defect of the thymus in the hairless dog seems to be different from that in athymic nude mice and rats. Further studies are needed to elucidate the immunological response and function in hairless dogs. 相似文献
72.
The photosynthetic reaction centers (RC) of the green bacterium Chloroflexus aurantiacus have been investigated by spectral and electrometrical methods. In these reaction centers, the secondary quinone was found to be reconstituted by the addition of ubiquinone-10. The equilibrium constant of electron transfer between primary (QA) and secondary (QB) quinones was much higher than that in RC of purple bacteria. The QB binding to the protein decreased under alkalinization with apparent pK 8.8. The single flash-induced electric responses were about 200 mV. An additional electrogenic phase due to the QB protonation was observed after the second flash in the presence of exogenous electron donors. The magnitude of this phase was 18% of that related to the primary dipole (P+QA-) formation. Since the C. aurantiacus RC lacks H-subunit, this subunit was not an obligatory component for electrogenic QB protonation. 相似文献
73.
Cytochrome b558 of pig blood neutrophils was partially purified, and its EPR spectra were measured. The cytochrome b558 was solubilized from membranes with the detergent n-heptyl-beta-thioglucoside and purified by DEAE-Sepharose and heparin-Sepharose chromatographies. The small and large subunits of cytochrome b558 were detected on gel by immunoblotting. A solution of the purified, undenatured cytochrome b558 at 85-108 microM concentration was obtained. The concentrated cytochrome b558 showed an EPR signal at a g value of 3.26 with a bandwidth of 100 G at 10 K. Addition of 2 mM KCN had no effect on the low spin signal at g = 3.26 but caused disappearance of a minor high spin signal. The cyanide-insensitive signal at g = 3.26 disappeared completely on reduction with Na2S2O4. These results suggest that the g = 3.26 signal is characteristic of the low spin heme in cytochrome b558 of neutrophils. 相似文献
74.
Expression of human soluble tissue factor in yeast and enzymatic properties of its complex with factor VIIa. 总被引:2,自引:0,他引:2
Y Shigematsu T Miyata S Higashi T Miki J E Sadler S Iwanaga 《The Journal of biological chemistry》1992,267(30):21329-21337
The extracellular domain of human tissue factor (TF, amino acids 1-217) was expressed in Saccharomyces cerevisiae, using the inducible yeast acid phosphatase promoter and the yeast invertase signal sequence to direct its secretion into the culture broth. Two active soluble forms sTF alpha (high molecular weight form) and sTF beta (low molecular weight form) were purified, the yield being approximately 10 and 1 mg/liter of culture supernatant, respectively. sTF alpha had an apparent molecular mass of 150 kDa on SDS-polyacrylamide gel electrophoresis and contained more than 200 residues of mannose/mol of protein. sTF beta had an apparent molecular mass of 37 kDa and contained 22 residues of mannose/mol of protein. N-Glycosidase F treatments of both rTFs reduced the apparent molecular mass to 35 kDa. The amino-terminal sequences and amino acid compositions of sTF alpha and sTF beta were consistent with those deduced from the cDNA sequence, thereby indicating that the difference in molecular mass is caused by heterogeneity of oligosaccharide structures. Of these recombinant TFs, sTF beta enhanced factor VIIa-amidolytic activity 40-fold toward the chromogenic substrate and 147-fold toward the fluorogenic substrate, affecting mainly the kcat value. The enhancement was comparable with that of TF purified from human placenta. The TF-mediated enhancement of factor VIIa-amidolytic activity was inhibited by heparin-activated antithrombin III, forming a high molecular weight complex. As treatment of sTF beta with denaturants such as guanidine hydrochloride or urea led to a biphasic loss of the activity, the extracellular domain of TF probably consists of two discrete domains. This expression system provides a significant amount of the extracellular domain of TF so that studies of interactions with factor VII are feasible. 相似文献
75.
Azo compounds enable us to generate peroxyl radicals by thermal decomposition at a constant rate and at a desired site, that is, water-soluble compounds produce initiating radicals in an aqueous phase and lipid-soluble compounds initiate the oxidation within the membrane-lipid layer. Using these radicals generated in different sites, we oxidized red blood cell ghost membranes to study the relationships between alpha-tocopherol depletion, initiation of lipid peroxidation, and protein damage. When radicals were generated in the aqueous phase, the loss of membrane protein thiols was observed concurrently with the consumption of membrane tocopherol and after tocopherol was exhausted the peroxidation of membrane lipids occurred. On the other hand, when radicals were initiated within the lipid region, the oxidation of thiols and the formation of thiobarbituric acid-reactive substances were suppressed to give an induction period until tocopherol fell below a critical level. Our results indicate that the surface thiols of extrinsic proteins may compete with alpha-tocopherol for trapping aqueous radicals and spare tocopherol to some extent, whereas the oxidation of intrinsic buried thiols may commence due to lipid-derived radicals produced after tocopherol was consumed. In conclusion, alpha-tocopherol in the membrane can break the free radical chain efficiently to inhibit the lipid peroxidation. However, the effect of tocopherol on the inhibition of membrane protein damage, exhibited by the loss of thiols and the formation of high-molecular-weight proteins, would be different depending on the site of initial radical generation. 相似文献
76.
Memory impairment and morphological changes in rats induced by active fragment of anti-nerve growth factor-antibody 总被引:2,自引:0,他引:2
T Nabeshima S Ogawa H Ishimaru T Kameyama T Fukuta R Takeuchi K Hayashi 《Biochemical and biophysical research communications》1991,175(1):215-219
Treatment of rats with a specific Fab' fragment of anti-nerve growth factor (NGF)-antibody (anti-NGF, 12, 120 and 400 micrograms/4 weeks, i.c.v.) impaired their learning ability. The distance of swimming of anti-NGF-treated rats in a water maze was shortened more slowly by training than that of control rats. Anti-NGF treatment altered the staining of nuclei of cells in the hippocampus, parietal cortex and dentate gyrus with hematoxylin. It is suggested that the anti-NGF-induced amnesia could be due to change in nuclear morphology. 相似文献
77.
78.
S Sagawa K Miki F Tajima H Tanaka J K Choi L C Keil K Shiraki J E Greenleaf 《Journal of applied physiology》1992,72(1):128-134
The mechanism for reduced voluntary water intake during water immersion was studied in eight men (19-25 yr of age) immersed to the neck while sitting for 3 h at 34.5 degrees C or in air at 28 degrees C when euhydrated (Eu-H2O and Eu-air, respectively) and hypohydrated (Hypo-H2O and Hypo-air) by 3.6% body weight loss. Thirst sensations (degree of thirst, mouth dryness and taste, drinking desirability, and stomach fullness) were similar at the beginning of Hypo-air and Hypo-H2O test periods. Initial drinking of tap water (15 degrees C) was 216 +/- 30 ml/7 min (P less than 0.05) with Hypo-air, decreased to 108 +/- 28 ml/7 min (P less than 0.05) with Hypo-H2O, and was 10-50 ml/10-30 min thereafter. Intake was less than 10 ml/10-30 min in Eu-air, and there was no drinking in Eu-H2O. Within the first 10 min of immersion, compared with Hypo-air findings, the significant reduction in drinking in the Hypo-H2O experiment was associated with unchanged plasma Na+, plasma osmolality, heart rates, and mean arterial pressures; the different responses were increased cardiac output, plasma volume, and atrial natriuretic peptides and decreased plasma renin activity and arginine vasopressin. Thus the extracellular pathway, as opposed to the osmotic pathway, appears to be the major mechanism for immersion-induced suppression of drinking. 相似文献
79.
Hydrocortisone-induced enhancement of expression and changes in methylation of pepsinogen genes in stomach mucosa of the developing rat 总被引:1,自引:0,他引:1
80.
Structural studies of rat cathepsin E: amino-terminal structure and carbohydrate units of mature enzyme 总被引:3,自引:0,他引:3
S Yonezawa T Takahashi M Ichinose K Miki J Tanaka S Gasa 《Biochemical and biophysical research communications》1990,166(2):1032-1038
The amino-terminal structure of rat gastric cathepsin E was identified and compared with the corresponding regions of human procathepsin E and other aspartic proteinases. The alignment revealed that cathepsin E has the most extended amino-terminal structure in aspartic proteinases, thus suggesting that the activation peptide (propeptide) of the human enzyme is 39-residues long. Analysis of oligosaccharide units suggested that rat cathepsin E possesses one N-linked carbohydrate unit, probably of the high mannose type. No evidence was obtained for the presence of O-linked sugars in rat cathepsin E. 相似文献