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排序方式: 共有67条查询结果,搜索用时 15 毫秒
1.
Inhibition of testosterone biosynthesis by ethanol. Relation to hepatic and testicular acetaldehyde, ketone bodies and cytosolic redox state in rats. 总被引:1,自引:0,他引:1 下载免费PDF全文
C J Eriksson T V Widenius R H Ylikahri M Hrknen P Leinonen 《The Biochemical journal》1983,210(1):29-36
In experiments in which liver and testis freeze-stops were performed on pentobarbital-anaesthetized rats, ethanol (1.5 g/kg body wt.) reduced plasma testosterone concentration from 13.1 to 3.2 nmol/litre. 4-Methylpyrazole abolished the ethanol-induced hepatic and testicular increase in the lactate/pyruvate ratio, and the testicular acetaldehyde level, but did not diminish the reduction in plasma testosterone concentration. In testes, but not in liver, ethanol decreased the 3-hydroxybutyrate/acetoacetate ratio, and 4-methylpyrazole did not prevent this effect. In experiments in which freeze-stop was performed after cervical dislocation, ethanol decreased the testis testosterone concentration from 590 to 220 pmol per g wet wt. The effects of ethanol and 4-methylpyrazole on testis acetaldehyde, lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were the same as found during anaesthesia. The NAD+-dependent ethanol oxidation capacity in testis ranged from 0.1 to 0.2 mumol/min per g wet wt. and seemed to be inhibited by 4-methylpyrazole both in vivo and in vitro. In additional experiments, ethanol doses between 0.3 and 0.9 g/kg body wt. did not alter the plasma testosterone concentration in rats treated, or not treated, with cyanamide, which induced elevated acetaldehyde levels in blood and testes. The results suggest that ethanol-induced inhibition of testosterone biosynthesis was not caused by extratesticular redox increases, or by extra- or intra-testicular acetaldehyde per se. The inhibition is accompanied by changes in testicular ketone-body metabolism. 相似文献
2.
To investigate the effects of acute ethanol administration on the production of proaggregatory thromboxane A2 (TxA2) and anti-aggregatory prostacyclin (PGI2), ethanol (1.5 g/kilogram body weight) was given to eight healthy nonsmoking men, and the stable metabolites thromboxane B2 (TxB2) and 6-keto-prostaglandin F1α (6-keto-PGF1α), respectively, measured by radioimmunoassay from serial blood samples before drinking and during the ensuing 18 hours. Each subject was studied as his own control on another occasion when only an equivalent volume of water was given. Serum TxB2 level decreased (p < 0.01) from 206 + 31 ng/ml (mean) ± S.E. to 1672 ± 24 and 161 ± 23 ng/ml (two and four hours after beginning of the drinking, respectively) concomitantly with the attainment of maximal blood ethanol concentrations (about 120 mg/100 ml), whereas no changes occurred in plasma 6-keto-PGF1α concentrations. Our results may provide an explanation for known effects of ethanol on platelet aggregation. They also raise speculation whether TxA2-inhibition and the antiatherogenic effect of alcohol intake are somehow related. 相似文献
3.
Reino Heikkil Tore Godal Aase Henriksen Jens-Gustav Iversen 《Experimental cell research》1981,136(2):447-454
F(ab′)2 anti-μ, as well as anti-δ and anti-γ heavy chains have been found to induce strong increases in the influx of 86Rb+ (a potassium analogue) in cell suspensions from a proportion of human lymphomas staining monoclonally for B cells. The specificity of the response corresponded to the surface immunoglobulin (sIg) isotype present on lymphoma cells. Even when carried out under closely analogous conditions, no relationship between capping and 86Rb+ influx was observed. On the other hand, an association between 86Rb+ influx and mitogenic response to anti-immunoglobulin (anti-Ig) was observed with concordant results in 19 out of 21 comparisons made. These findings suggest that 86Rb+ influx, which appears to be associated with mitogenic signals, and capping may arise as independent phenomena even when elicited through the same membrane receptor (sIg). 相似文献
4.
5.
Lehtivarjo J Tuppurainen K Hassinen T Laatikainen R Peräkylä M 《Journal of biomolecular NMR》2012,52(3):257-267
While chemical shifts are invaluable for obtaining structural information from proteins, they also offer one of the rare ways
to obtain information about protein dynamics. A necessary tool in transforming chemical shifts into structural and dynamic
information is chemical shift prediction. In our previous work we developed a method for 4D prediction of protein 1H chemical shifts in which molecular motions, the 4th dimension, were modeled using molecular dynamics (MD) simulations. Although
the approach clearly improved the prediction, the X-ray structures and single NMR conformers used in the model cannot be considered
fully realistic models of protein in solution. In this work, NMR ensembles (NMRE) were used to expand the conformational space
of proteins (e.g. side chains, flexible loops, termini), followed by MD simulations for each conformer to map the local fluctuations.
Compared with the non-dynamic model, the NMRE+MD model gave 6–17% lower root-mean-square (RMS) errors for different backbone
nuclei. The improved prediction indicates that NMR ensembles with MD simulations can be used to obtain a more realistic picture
of protein structures in solutions and moreover underlines the importance of short and long time-scale dynamics for the prediction.
The RMS errors of the NMRE+MD model were 0.24, 0.43, 0.98, 1.03, 1.16 and 2.39 ppm for 1Hα, 1HN, 13Cα, 13Cβ, 13CO and backbone 15N chemical shifts, respectively. The model is implemented in the prediction program 4DSPOT, available at . 相似文献
6.
José Luis Reino Raul F. Guerrero Rosario Hernández-Galán Isidro G. Collado 《Phytochemistry Reviews》2008,7(1):89-123
Trichoderma species are free-living fungi that are highly interactive in root, soil and foliar environments and have been used successfully
in field trials to control many crop pathogens. Structural and biological studies of the metabolites isolated from Trichoderma species are reviewed. This review, encompassing all the literature in this field up to the present and in which 269 references
are cited, also includes a detailed study of the biological activity of the metabolites, especially the role of these metabolites
in biological control mechanisms. Some aspects of the biosynthesis of these metabolites and related compounds are likewise
discussed. 相似文献
7.
Isolation and Identification of Aspergillus fumigatus Mycotoxins on Growth Medium and Some Building Materials 总被引:1,自引:0,他引:1 下载免费PDF全文
Susanna M. Nieminen Riikka Krki Seppo Auriola Mika Toivola Hartmut Laatsch Reino Laatikainen Anne Hyvrinen Atte von Wright 《Applied microbiology》2002,68(10):4871-4875
Genotoxic and cytotoxic compounds were isolated and purified from the culture medium of an indoor air mold, Aspergillus fumigatus. One of these compounds was identified as gliotoxin, a known fungal secondary metabolite. Growth of A. fumigatus and gliotoxin production on some building materials were also studied. Strong growth of the mold and the presence of gliotoxin were detected on spruce wood, gypsum board, and chipboard under saturation conditions. 相似文献
8.
Heikki Kallio Reino R. Linko Tapani Pyysalo Irmeli Puntari 《Analytical biochemistry》1978,90(1):359-364
The major keto acids in arctic bramble,Rubus arcticus L. were investigated. The acids were isolated with anionic and cationic ion-exchange resins, converted to 2,4-dinitrophenylhydrazones, and purified with an Al2O3 column. The derivatives were separated on a silica gel G thin-layer plate and esterified with methanol-HCl and the methyl esters of the keto acid 2,4-dinitrophenylhydrazones formed were analyzed on an OV-1-glass capillary gas-liquid chromatography column and with mass spectrometry. 2-Oxoglutaric, pyruvic, oxaloacetic, and glyoxylic acids were identified. The mass spectra of the derivatives are presented. 相似文献
10.
Luís Reino Stefan Schindler Joana Santana Miguel Porto Rui Morgado Francisco Moreira Ricardo Pita António Mira John T. Rotenberry Pedro Beja 《European Journal of Wildlife Research》2018,64(4):48
Land use intensification may create habitats that organisms perceive as suitable, but where reproduction or survival is insufficient to maintain self-sustaining populations. Such conditions may qualify as ecological traps, but their existence is often hard to prove. Here, we provide a practical framework to evaluate a potential ecological trap resulting from mismatch between habitat preferences and predation risk, focusing on ground-nesting farmland birds of conservation concern. The framework is based on species-specific associations with safe or unsafe habitat types (i.e. field and landscape types with high or low nest survival), and the occurrence of risk avoidance (i.e. negative responses to predator abundances or to nest failure rates after controlling for habitat effects). Bird densities were far more influenced by field characteristics than landscape context. Corn bunting and fan-tailed warbler were associated with tall swards (safe habitats), and did not show risk avoidance. Tawny pipit and and Galerida larks were associated with short swards (unsafe habitats), with the former avoiding fields with high nest predation rates, and the later avoiding high mongoose abundances. Short-toed lark was associated with fields with short swards and low nest trampling rates. Results suggest that short-toed lark may be the most vulnerable to ecological trapping, because it nests on unsafe habitats and did not show predation risk avoidance. Our approach provides a practical first step to infer vulnerability to a potential ecological trap, though further research is needed to confirm this effect. Management actions increasing nest survival in short sward fields will likely favour grassland bird conservation in intensive Mediterranean farmland. 相似文献