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71.
Livers from fasted or fed pigs were perfused for 5 h with Krebs-Ringer bicarbonate buffer containing human erythrocytes, bovine serum albumin, glucose, and amino acids. Liver viability was estimated by color, consistency, portal pressure, bile flow, electrolyte changes, and glucose levels in the perfusate, urea synthesis, [1-14C]leucine incorporation into protein, oxygen uptake, and histological examination. It was shown that the liver was maintained in good condition throughout the perfusions. The apolipoprotein B (apoB) and apolipoprotein A-I (apoA-I) in the perfusate were measured by solid phase radioimmunoassay. In the fasted state, the amount of apoB released was greatest in the low density lipoprotein (LDL) fraction and the amount was especially high during the 1st h. There was no increase of apoB in this fraction by feeding. The apoB in the very low density lipoprotein (VLDL) fraction was less than that in the LDL fraction in the fasted state, and it increased more than 2-fold in the fed animals. The amount of apoA-I was greatest in the 1.21 bottom fraction and was relatively small in the high density lipoprotein (HDL) fraction. The HDL fraction contained approximately one-twentieth as much apoA-I as the 1.21 bottom fraction in the fasted condition. In the fed state, apoA-I in the HDL fraction increased markedly, although the amount was still less than in the 1.21 bottom fraction. 相似文献
72.
Large single crystals of isocitrate dehydrogenase from Azotobacter vinelandii have been grown by vapor diffusion from ammonium sulfate and phosphate solutions. The crystals are tetragonal, space group P42212 with cell dimensions , . There are two molecules of 80,000 molecular weight per asymmetric unit. Native data to 5.5 Å resolution have been collected on a diffractometer. A rotation function using data between 10 Å and 6 Å resolution indicates three possible orientations of the non-crystallographic 2-fold axis relating the two molecules. 相似文献
73.
B A Doneen D Chung D Yamashiro P Y Law H H Loh C H Li 《Biochemical and biophysical research communications》1977,74(2):656-662
The opiate activities of some derivatives and enzymatic digests of camel and human β-endorphin were determined in the guinea pig ileum and rat brain opiate receptor binding assays. Derivatives of β-endorphins altered within the amino-terminal five residues showed pronounced losses in activity. Anisylation of the C-terminal glutamic acid residue of βh-endorphin produced only small reductions in activity. Chymotryptic digestion greatly weakened the opiate activities of βh-endorphin, whereas carboxypeptidase A, tryptic and leucine aminopeptidase digests showed only small losses in potency. The C-terminus of β-endorphin appears to contribute little directly to opiate activity. Amino acid analysis and assay of the leucine aminopeptidase digests suggest that the larger potency of β-endorphin relative to Met-enkephalin may be a consequence of its greater resistance to exopeptidase attack. 相似文献
74.
Capillaries of the adrenal cortex possess aminopeptidase A and angiotensin-converting-enzyme activities. 总被引:6,自引:0,他引:6 下载免费PDF全文
The enzymes required to convert the prohormone angiotensin I into angiotensins II and III, secretagogues of aldosterone, are enriched in association with capillary endothelium isolated from rat adrenal cortex. Thus the secretion of aldosterone may be controlled, in part, by processing of peptides occurring within the adrenal gland itself. 相似文献
75.
Summary The effect of ozone exposure on Saccharomyces cerevisiae was studied. Factors such as ozone concentration, treatment time, media, initial cell concentration and growth phase were shown to influence ozone response in this organism. Logarithmic phase cells were much more sensitive than stationary phase cells to the lethal effect of ozone.The radiation-sensitive mutants rad3, rad6, rad51 and rad52 of S. cerevisiae were exposed, in water, to 50 ppm of ozone for 30 min. On comparing their survival curves, the rad51 and the rad52 mutants showed a greater sensitivity to ozone exposure than the wild type. 相似文献
76.
A simple one-step procedure is described on the isolation of androgen glucuronides from various rat tissues. This procedure uses polyacrylamide gel electrophoresis, and permits a quantitative isolation of a single band containing the total androgen glucuronides without the contamination of free androgens and androgen sulfates. This procedure was used to determine the ability of various tissues of the rat to form androgen glucuronides directly when they were incubated with 1,2-[3H]-testosterone (0.1 μM) . Of eleven organs studied, only the accessory sex organs (ventral prostate, seminal vesicle, and coagulating gland), liver, and kidney were capable of forming androgen glucuronides. At the end of a one-hour incubation period, approximately 1% of the total radiolabeled steroids in the prostatic tissue minces were in the form of glucuronide conjugates. The predominant androgen glucuronide formed in the accessory sex organs was 5α-androstane-3α,17β-diol 17β-d-glucuronide. This is in contrast to the rat liver and kidney in which testosterone glucuronide was the predominant conjugate.A similar amount of labeled glucuronide conjugates was formed from either [3H]-testosterone, [3H]-dihydrotestosterone or [3H]-androstenedione, whereas negligible amount of steroid conjugates was formed from [3H]-cortisol. The formation of androgen glucuronides requires metabolically active tissues; furthermore, the conjugation process was inhibited by the antiandrogen, cyproterone acetate, or by metabolic inhibitors, such as oligomycin or N-ethylmaleimide. 相似文献
77.
In order to evaluate the efficacy of albendazole for the treatment of taeniasis, regimens of 400 mg x 1 day, 800 mg x 2 days, 800 mg x 3 days, 1200 mg x 2 days, and 1200 mg x 3 days were compared. Of 66 cases treated and investigated 7-14 days after treatment, 52 were still expelling proglottids. Three months posttreatment, these cases were re-treated with atabrine at 1.2 g per case for males and 1.0 g per case for females. Fifty-seven patients expelled worms or parts of tapeworms. The nine negatives may represent the number cured by the treatment with albendazole. The cure rates with albendazole for various regimens were up to 50% for 800 mg x 3 days, 1200 mg x 2 days or 1200 mg x 3 days, 14.3% for 800 mg x 2 days, and 0% for 400 mg x 1 day or 800 mg x 1 day. This study shows that albendazole is not very effective in the treatment for taeniasis. 相似文献
78.
Jian Xu Chung Y. Hsu Herman Junker Steven Chao Edward L. Hogan Julie Chao 《Journal of neurochemistry》1991,57(3):975-980
Activation of the kallikrein-kinin system has been implicated in the pathogenesis of vasogenic brain edema and posttraumatic vascular injury. We determined the levels of kininogen and kinin in an experimental spinal cord injury model in the rat. Kininogen content in traumatized cord segments increased in a time-dependent manner. Western blot analysis showed that the kininogen in traumatized cord comigrates with 68K low-molecular-weight kininogen or T-kininogen. Trypsin treatment of the kininogen in traumatized cord released both bradykinin and T-kinin, which were separated by HPLC and quantified with a kinin radioimmunoassay. Endogenous kinin levels in the frozen spinal cord also increased up to 40-fold 2 h after injury as compared with controls. The results demonstrate an increased accumulation of kininogen and its conversion to vasoactive kinins in experimental spinal cord injury. 相似文献
79.
Heart and liver mitochondrial, as well as liver peroxisomal, carnitine acetyltransferase was purified to apparent homogeneity and some properties, primarily of heart mitochondrial carnitine acetyltransferase, were determined. Hill coefficients for propionyl-CoA are 1.0 for each of the enzymes. The molecular weight of heart mitochondrial carnitine acetyltransferase, determined by SDS-PAGE, is 62,000. It is monomeric in the presence of catalytic amounts of substrate. Polyclonal antibodies against purified rat liver peroxisomal carnitine acetyltransferase precipitate liver and heart mitochondrial and liver peroxisomal carnitine acetyltransferase, but not liver peroxisomal carnitine octanoyltransferase. Liver peroxisomes, mitochondria, and microsomes and heart mitochondria all give multiple bands on Western blotting with the antibody against carnitine acetyltransferase. Major protein bands occur at the molecular weight of carnitine acetyltransferase and at 33 to 35 kDa. 相似文献
80.
A novel enzyme, arylalkyl acylamidase, which shows a strict specificity for N-acetyl arylalkylamines, but not acetanilide derivatives, was purified from the culture broth of Pseudomonas putida Sc2. The purified enzyme appeared to be homogeneous, as judged by native and SDS/PAGE. The enzyme has a molecular mass of approximately 150 kDa and consists of four identical subunits. The purified enzyme catalyzed the hydrolysis of N-acetyl-2-phenylethylamine to 2-phenylethylamine and acetic acid at the rate of 6.25 mumol.min-1.mg-1 at 30 degrees C. It also catalyzed the hydrolysis of various N-acetyl arylalkylamines containing a benzene or indole ring, and acetic acid arylalkyl esters. The enzyme did not hydrolyze acetanilide, N-acetyl aliphatic amines, N-acetyl amino acids, N-acetyl amino sugars or acylthiocholine. The apparent Km for N-acetylbenzylamine, N-acetyl-2-phenylethylamine and N-acetyl-3-phenylpropylamine are 41 mM, 0.31 mM and 1.6 mM, respectively. The purified enzyme was sensitive to thiol reagents such as Ag2SO4, HgCl2 and p-chloromercuribenzoic acid, and its activity was enhanced by divalent metal ions such as Zn2+, Mg2+ and Mn2+. 相似文献