排序方式: 共有40条查询结果,搜索用时 15 毫秒
31.
Background
Intoxication from the psychostimulant methamphetamine (METH) because of cardiovascular collapse is a common cause of death within the abuse population. For obvious reasons, the heart has been taken as the primary target for this METH-induced toxicity. The demonstration that failure of brain stem cardiovascular regulation, rather than the heart, holds the key to cardiovascular collapse induced by the pesticide mevinphos implicates another potential underlying mechanism. The present study evaluated the hypothesis that METH effects acute cardiovascular depression by dampening the functional integrity of baroreflex via an action on brain stem nuclei that are associated with this homeostatic mechanism. 相似文献32.
The narrow host range of infection supporting the long-term propagation of hepatitis B and C viruses is a major limitation that has prevented a more thorough understanding of persistent infection and t... 相似文献
33.
Genome-wide comparison of differences in the integration sites of interspersed repeats between closely related genomes 总被引:2,自引:2,他引:0
Mamedov I Batrak A Buzdin A Arzumanyan E Lebedev Y Sverdlov ED 《Nucleic acids research》2002,30(14):e71
A technique for genome-wide detection of differences in the integration site positions of interspersed repeats in related genomes (DiffIR) is described. The technique is based on a whole- genome selective PCR amplification of the repeats’ flanking regions followed by a differential hybridization screening of the arrayed library of the selected amplicons. The technique was successfully applied to the comparison of the integration sites in the human and chimpanzee genomes, allowing us to discover 11 new human-specific integrations of human endogenous retrovirus, K family (HML-2) long terminal repeats. 相似文献
34.
Alton G; Hasilik M; Niehues R; Panneerselvam K; Etchison JR; Fana F; Freeze HH 《Glycobiology》1998,8(3):285-295
Direct utilization of mannose for glycoprotein biosynthesis has not been
studied because cellular mannose is assumed to be derived entirely from
glucose. However, animal sera contain sufficient mannose to force uptake
through glucose-tolerant, mannose-specific transporters. Under
physiological conditions this transport system provides 75% of the mannose
for protein glycosylation in human hepatoma cells despite a 50- to 100-fold
higher concentration of glucose. This suggests that direct use of mannose
is more important than conversion from glucose. Consistent with this
finding the liver is low in phosphomannose isomerase activity
(fructose-6-P<->mannose-6-P), the key enzyme for supplying
glucose-derived mannose to the N-glycosylation pathway. [2- 3H] Mannose is
rapidly absorbed from the intestine of anesthetized rats and cleared from
the blood with a t1/2of 30 min. After a 30 min lag, label is incorporated
into plasma glycoproteins, and into glycoproteins of all organs during the
first hour. Most (87%) of the initial incorporation occurs in the liver,
but this decreases as radiolabeled plasma glycoproteins increase.
Radiolabel in glycoproteins also increases 2- to 6-fold in other organs
between 1-8 h, especially in lung, skeletal muscle, and heart. These organs
may take up hepatic- derived radiolabeled plasma glycoproteins.
Significantly, the brain, which is not exposed to plasma glycoproteins,
shows essentially no increase in radiolabel. These results suggest that
mammals use mannose transporters to deliver mannose from blood to the liver
and other organs for glycoprotein biosynthesis. Additionally, contrary to
expectations, most of the mannose for glycoprotein biosynthesis in cultured
hepatoma cells is derived from mannose, not glucose. Extracellular mannose
may also make a significant contribution to glycoprotein biosynthesis in
the intact organism.
相似文献
35.
The phylogeny and substitution rates of the mammalian X chromosome- located
and autosomal phosphoglycerate kinase and pyruvate dehydrogenase genes were
investigated. Compatibility analysis was used to show reticulate evolution
in these genes. Analysis of the marsupial, mouse, and human
phosphoglycerate kinase genes suggests that at least two recombination
events have taken place, one occurring about the time of the
placental-marsupial split involving exons 1-5 and the other before the
primate-rodent split involving exons 9-10. Similar analysis of the pyruvate
dehydrogenase genes indicates a recombination event involving exons 2-3 at
a time before the primate-rodent split and a gene conversion between exons
3-4 in the human somatic and testis- specific pyruvate dehydrogenase genes
after the primate-rodent split. This demonstrates that genetic exchange can
occur between paralogous genes at widely separated chromosomal locations.
Estimation of nucleotide substitution rates in these genes confirmed a
higher substitution rate in the pyruvate dehydrogenase genes. In the
phosphoglycerate kinase genes, there is no difference between the
substitution rates in mice and humans and between the X chromosome- and
autosome-located genes. A greater substitution rate was noted in the mouse
autosomal pyruvate dehydrogenase gene when compared with the other mouse
and human genes. This may be a result of either directional natural
selection or a relaxation of functional constraint at this specific gene.
相似文献
36.
Synaptosomes purified from spinal cord and from different rat brain areas exhibit peptide hydrolase activity, cleaving substance P (SP), bradykinin, THRH, LHRH, and neurotensin. The lowest activity for all the peptides tested was found in spinal cord, while the region with the highest degrading activity depended on the substrate: for substance P, it was striatum and cortex; for bradykinin, hypothalamus, and medulla oblongata; for THRH, striatum; for LHRH, midbrain; and for neurotensin, hippocampus. Degradation of substance P takes place at the plasma membrane of synaptosomes. Synaptosome ghosts cleave substance P (pH optimum 7–9,K
m–2.5×10–5 M,V
max–130 nmol·hr–1·mg protein–1 and also a number of its C-terminal fragments. Effects of the inhibitors show that several different classes of peptidases and proteases are involved in the degradation process. Peptide cleavage represents the probable pathway of synaptosomal inactivation of substance P. 相似文献
37.
Background
Despite its clinical importance, a dearth of information exists on the cellular and molecular mechanisms that underpin brain stem death. A suitable neural substrate for mechanistic delineation on brain stem death resides in the rostral ventrolateral medulla (RVLM) because it is the origin of a life-and-death signal that sequentially increases (pro-life) and decreases (pro-death) to reflect the advancing central cardiovascular regulatory dysfunction during the progression towards brain stem death in critically ill patients. The present study evaluated the hypothesis that heme oxygnase-1 (HO-1) may play a pro-life role as an interposing signal between hypoxia-inducible factor-1 (HIF-1) and nitric oxide synthase I (NOS I)/protein kinase G (PKG) cascade in RVLM, which sustains central cardiovascular regulatory functions during brain stem death. 相似文献38.
The degree of halophily inRhodococcus erythropolis andHalobacterium salinarum was found to increase under microaerobic conditions. This was evidently due to the fact that the two stress factors (high
salt and low oxygen concentrations) acted in an antagonistic manner. The results obtained suggest that the aeration rate should
be taken into account while estimating the degree of halophily of a microorganism. 相似文献
39.
40.
A. G. Globa Ya. I. Alekseev V. G. Arzumanyan V. A. Zaborova A. A. Guridov 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2013,7(2):175-177
A test system has been developed for determination of propionic bacterial species inhabiting the human skin. This system developed in the real time PCR format is applicable for quantitative determination and also detection of genomes of the following Propionibacterium species: P. acnes, P. granulosum, and P. avidum. This system was used for analysis of wash samples from the skin of 17 pentathlon sportsmen and 16 students. All three species of propionic bacteria were found in all skin wash samples. However, contamination with P. acnes was two times higher in the control group than in the group of pentathlon sportsmen. 相似文献