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991.
992.
993.
The association between lipoproteins, cholesterol and cholesteryl esters is very well known to facilitate both the transport in plasma and the entry of these non-polar compounds into the cellular compartment. However, recent observations suggest that in addition to cholesterol, lipoproteins contain several other steroids in their lipoidal metabolite forms which may be transported in the very low, low and high density lipoproteins in human serum. Using the important androgen and oestrogen precursor, dehydroepiandrosterone (DHEA), the biosynthetic formation of lipoidal DHEA was demonstrated in human serum. Serum was also fractionated into its lipoprotein components during the course of its incubation with tritiated DHEA. A progressive movement of the label from the fraction containing the conventional steroid binding-proteins to the lipoproteins was observed with the fraction containing the low density lipoproteins demonstrating the greatest incorporation of the label. This displacement occurred simultaneous to an extensive esterification of the labelled DHEA in serum. After 6 h of incubation, approx. 90% of the radioactivity in all the lipoprotein fractions was in the lipoidal form. Very little labelled lipoidal DHEA was associated with the serum protein fraction throughout the duration of incubation. These data suggest that lipoproteins act as the carriers of lipoidal DHEA following its formation from the non-conjugate parent steroid in serum. 相似文献
994.
Formation of lipoidal steroids in follicular fluid 总被引:1,自引:0,他引:1
The presence of high levels of lipoidal pregnenolone in follicular fluid has recently been established although no evidence has been presented concerning its possible origin. The following investigation focuses on the enzymatic conversion of non-conjugated steroids into their lipoidal derivatives in preovulatory follicular fluid obtained from women undergoing in vitro fertilization. Our observations indicated that pregnenolone, an important precursor steroid, was acylated at a similar rate as cholesterol in follicular fluid. Similar studies were subsequently conducted with serum obtained from a pool of normal women and women undergoing follicular stimulation which showed little difference to the results obtained in follicular fluid. Further studies using dehydroepiandrosterone, androst-5-ene-3 beta,17 beta-diol, estradiol and dihydrotestosterone were were also performed to monitor their respective lipoidal conversion percentages in follicular fluid which revealed a marked difference of conversion rates between steroids. The indirect identification of the lipoidal pregnenolone derivatives formed in follicular fluid was also conducted by incubating radiolabelled pregnenolone in follicular fluid. The fatty acid components of the resulting lipoidal pregnenolone derivatives showed a marked resemblance to those of cholesteryl esters formed in plasma by the enzymatic activity of lecithin:cholesterol acyltransferase. The pregnenolone derivatives were comprised predominantly of unsaturated fatty acids such as linoleate, palmitoleate, oleate, linolenate and arachidonate while saturated fatty acids, namely palmitate, constituted 20% of the total lipoidal pregnenolone. 相似文献
995.
Two nuclear oncogenic proteins, P135gag-myb-ets and p61/63myc, cooperate to induce transformation of chicken neuroretina cells 总被引:7,自引:4,他引:3 下载免费PDF全文
P Amouyel V Laudet P Martin R P Li B Quatannens D Stéhelin S Saule 《Journal of virology》1989,63(8):3382-3388
Several studies have shown that full transformation of primary rodent fibroblasts can be achieved in vitro through the cooperation of two oncogenes (usually one nuclear and one cytoplasmic) classified on the basis of different complementation groups. We have shown previously that cooperation between v-mil (cytoplasmic, serine-threonine kinase product), and v-myc (nuclear, DNA-binding product) is required to transform 7-day-old chicken neuroretina cells, which in usual culture medium do not rapidly proliferate. v-mil induces sustained growth of chicken neuroretina cells without transformation; v-myc fails to stimulate the proliferation of chicken neuroretina cells but is required to achieve transformation of the proliferating cells. Here, we present results indicating that the P135gag-myb-ets nuclear protein of avian erythroblastosis virus E26 is able to induce proliferation but not transformation of chicken neuroretina cells. v-myc is required in addition to P135gag-myb-ets to achieve chicken neuroretina cell transformation. In contrast, we found that the P135gag-myb-ets and P100gag-mil proteins are not able to cooperate in this system. 相似文献
996.
C Gianoulakis D Béliveau P Angelogianni M Meaney J Thavundayil V Tawar M Dumas 《Life sciences》1989,45(12):1097-1109
The purpose of the present studies was to investigate the activity of the adrenal gland and the pituitary beta-endorphin system in individuals from families with a 3 generation history of alcoholism, High Risk group, or from families without history of alcoholism, Low Risk group. All subjects had a medical examination, a drinking behavior personal interview and the Michigan Alcoholism Screening Test. Individuals with medical problems or excessive drinking were not included in the study. On the day of testing, a blood sample was taken at 9:00 a.m., then the subject drank a placebo drink or an ethanol solution (0.5 g ethanol/kg B.Wt.). Additional blood samples were taken at 15, 45 and 120 minutes post-drink. Results indicated that individuals of the High Risk group had lower basal levels of beta-endorphin like immunoreactivity (beta-EPLIR) than individuals of the Low Risk group. The dose of 0.5 g ethanol/kg B.Wt. induced an increase in the plasma content of beta-EPLIR of the High Risk group, but not of the Low Risk group. In the Low Risk group ethanol did not induce an increase above the 9:00 a.m. levels, however, it attenuated the beta-endorphin decrease overtime, observed following the placebo drink. Analysis of beta-endorphin-like peptides in the plasma of the High Risk group, with Sephadex G-75 chromatography indicated that the major component of the plasma beta-EPLIR was beta-lipotropin. Plasma cortisol levels, following ethanol intake, presented a small increase in the High Risk group but not in the Low Risk group. Both groups presented similar blood alcohol levels. The basal levels of immunoreactive cortisol and beta-endorphin in the plasma of individuals who were alcoholics, but had been abstinent for at least six months prior to testing were similar to the levels of the High Risk group. Thus there are differences both in the basal levels and in the response of the cortisol and the pituitary beta-endorphin system to an acute ethanol challenge between the two groups. 相似文献
997.
The structure of alpha-melanocyte-stimulating hormone (alpha-MSH) has been determined in the pars intermedia of the frog Rana ridibunda. Pulse-chase labeling of frog neurointermediate lobes with selective amino acids revealed that the composition of frog alpha-MSH is similar to that of alpha-MSH from all mammalian species yet studied. Tryptic mapping of nexly synthetized alpha-MSH generated two fragments with the following amino acid composition: (T1) Trp, Pro, Lys, Gly, Val and (T2) Tyr, Arg, Phe, His, Ser, Glu. Concurrently, alpha-MSH was purified from 100 neurointermediate lobes to apparent homogeneity by reverse-phase HPLC. The sequence of the peptide determined by automated Edman degradation was Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val. The structure of frog alpha-MSH is thus identical to mammalian des-N alpha-acetyl alpha-MSH and differs from the sequence of toad (Xenopus laevis) alpha-MSH only by the first residue (Ser instead of Ala). These results confirm that the sequence of alpha-MSH has been highly preserved during evolution. 相似文献
998.
Prenatal diagnosis of Niemann-Pick type C disease: current strategy from an experience of 37 pregnancies at risk. 下载免费PDF全文
M T Vanier C Rodriguez-Lafrasse R Rousson G Mandon J Boué A Choiset M F Peyrat C Dumontel M C Juge P G Pentchev 《American journal of human genetics》1992,51(1):111-122
Thirty-seven pregnancies at risk for Niemann-Pick type C disease were monitored by study of cultured amniotic fluid cells (8 cases) or chorionic villus cells (29 cases) in 23 couples over the period 1984-91. An early protocol combined determination of sphingomyelinase activity with electron microscopy. The current strategy, based on the demonstration of specific abnormalities in intracellular processing of exogenous cholesterol, combines the study of the early phase (first 6 h) of LDL-induced cholesteryl ester formation and the histochemical evaluation (filipin staining after 24 h of LDL uptake) of the LDL-induced accumulation of unesterified cholesterol. Thirteen fetuses were predicted to be affected. Confirmation of the diagnosis was made by study of cholesterol processing in fetal skin fibroblast cultures and/or by demonstration of a characteristic lipid storage in fetal liver, already present at 14 w gestation. Definition of the biochemical phenotype (classical, variant, or intermediate) of the index case, with regard to cholesterol-processing abnormalities, is an absolute prerequisite to adequate genetic counseling in a given family. Prenatal diagnosis has now proved a safe procedure in the predominant (approximately 85%) group of families with the classical phenotype. 相似文献
999.
G. Molin M -L. Johansson M. Ståhl S. Ahrné R. Andersson B. Jeppsson S. Bengmark 《Antonie van Leeuwenhoek》1992,61(3):175-183
The systematics of theLactobacillus population of the intestines of 88 different rats was studied; 80 rats had been fed on fermented oat-meal soup (Molin et al. 1992). One-hundred-twenty-twoLactobacillus strains from the intestinal mucosa were phenotypically classified together with twenty-eight reference strains ofLactobacillus andLeuconostoc, using 49 unit characters. Data were examined using Jaccard coefficient, and unweighted pair group algorithm with arithmetic averages. Two major and eleven minor clusters were defined at the 76% SJ-similarity level: Cluster 1 included thirty isolates which could not be identified further, but had resemblance to the type strains ofL. jensenii, L. gasseri, L. crispatus, and to some extent toL. acidophilus. Cluster 12 including fifty-four intestinal isolates was identified asL. reuteri; and so was cluster 13 (five isolates). Isolates of the major clusters were found in all parts of the intestines. The genomic homogeneity of theL. reuteri isolates was scrutinized by endonuclease restriction analysis of the chromosomal DNA, and the isolates could be divided into six genomic strains. 相似文献
1000.
The currently accepted type species of the genusTrichosporon Behrend isT. beigelii. This species has formerly been regarded as identical toT. cutaneum. However, these fungi are now known to represent separate species with different ecology. The first species described inTrichosporon wasT. ovoides, an agent of human white piedra. A neotype strain is designated for this species, while a lectotype strain is indicated forT. cutaneum. The nameT. beigelii is considered as doubtful and consequently cannot be maintained. 相似文献