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排序方式: 共有190条查询结果,搜索用时 15 毫秒
181.
Al-Hiti H Melenovský V Syrovátka P Kettner J Málek I Kautzner J 《Physiological research / Academia Scientiarum Bohemoslovaca》2011,60(2):303-308
In some patients, heart failure (HF) is associated with increased pulmonary vascular resistance (PVR). The magnitude and the reversibility of PVR elevation affect the HF management. Sildenafil has been recently recognized as potent PVR-lowering drug in HF. The aim of the study was to compare hemodynamic effects and pulmonary selectivity of sildenafil to prostaglandin E(1) (PGE(1)). Right-heart catheterization was performed in 13 euvolemic advanced HF patients with elevated PVR (6.3+/-2 Wood's units). Hemodynamic parameters were measured at the baseline, during i.v. infusion of PGE1 (alprostadil 200 ng · kg(-1) · min(-1)) and after 40 mg oral dose of sildenafil. Both drugs similarly reduced systemic vascular resistance (SVR), but sildenafil had higher effect on PVR (-28 % vs. -49 %, p = 0.05) and transpulmonary pressure gradient than PGE(1). The PVR/SVR ratio--an index of pulmonary selectivity, did not change after PGE(1) (p = 0.7) but it decreased by -32 % (p = 0.004) after sildenafil. Both drugs similarly reduced pulmonary artery mean and wedge pressures and increased cardiac index (+27 % and +28 %). Sildenafil led more often to transplant-acceptable PVR while causing smaller drop of mean systemic pressure than PGE(1). In conclusion, vasodilatatory effects of sildenafil in patients with heart failure are more pronounced in pulmonary than in systemic circulation. 相似文献
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184.
We report on the expression of a VEGF-like protein encoded by Parapoxvirus ovis in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. We show that a lysine residue at amino acid position 2 (K2) is an important determinant for the stability of this protein in S. cerevisiae. Replacement of K2 by an arginine results in stabilization of the protein. This observation suggests that this lysine may be a target for ubiquitinylation, which is a prerequisite for proteasome-mediated protein degradation. Interestingly, in S. pombe the lysine (K2) has no influence on the stability of the protein. This result indicates that the two yeast species exhibit significant differences in their protein degradation pathways. 相似文献
185.
Biotechnological production of the angiotensin‐converting enzyme inhibitory dipeptide isoleucine‐tryptophan 下载免费PDF全文
Lydia Michelke Andreas Deussen Karina Kettner Peter Dieterich Diana Hagemann Thomas M. Kriegel Melanie Martin 《Engineering in Life Science》2018,18(4):218-226
Peptides with angiotensin‐converting enzyme (ACE)‐inhibitory and antihypertensive effects are suggested as innovative food additives to prevent or treat hypertension. Currently, these substances are isolated from food proteins following nonselective hydrolysis as a mixture of ACE‐inhibitory peptides and other protein fragments. This study presents an innovative biotechnological method, based on recombinant DNA technology that was established to specifically produce the ACE‐inhibitory dipeptide isoleucine‐tryptophan. In a first step, a repetitive isoleucine‐tryptophan construct fused to the maltose‐binding protein was generated and expressed in Escherichia coli BL21 cells. The chromatographically purified recombinant fusion protein was enzymatically hydrolyzed using α‐chymotrypsin to liberate the dipeptide isoleucine‐tryptophan. The identity of the liberated isoleucine‐tryptophan was confirmed by MS and derivatization of its N‐terminus. The ACE‐inhibitory effect of the recombinant dipeptide on soluble and membrane bound ACE was found to be indistinguishable from the inhibitory potential of the chemically produced commercially available dipeptide. The established experimental strategy represents a promising approach to the biotechnical production of sufficient amounts of recombinant peptide‐based ACE‐inhibitory and antihypertensive substances that are applicable as functional food additives to delay or even prevent hypertension. 相似文献
186.
肝脏作为代谢器官,在人体内发挥着重要作用。随着肝病的发病率逐年上升,如何有效的保肝护肝已成为医学界和药学界共同面一临的巨大挑战之一。化学药物在治疗肝病的同时常常伴随各种毒副作用甚至更进一步的肝损伤,而中药凭借其安全性和有效性的优势在肝病治疗领域受到越来越多的重视。中药护肝已有悠久的历史,近年来随着技术的进步,更多更好的新型中药逐步上市,相关研究不断增多。本文将就这些研究成果进行阐述。 相似文献
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188.
Molecular evolution of olfactomedin 总被引:2,自引:0,他引:2
Olfactomedin is a secreted polymeric glycoprotein of unknown function,
originally discovered at the mucociliary surface of the amphibian olfactory
neuroepithelium and subsequently found throughout the mammalian brain. As a
first step toward elucidating the function of olfactomedin, its
phylogenetic history was examined to identify conserved structural motifs.
Such conserved motifs may have functional significance and provide targets
for future mutagenesis studies aimed at establishing the function of this
protein. Previous studies revealed 33% amino acid sequence identity between
rat and frog olfactomedins in their carboxyl terminal segments. Further
analysis, however, reveals more extensive homologies throughout the
molecule. Despite significant sequence divergence, cysteines essential for
homopolymer formation such as the CXC motif near the amino terminus are
conserved, as is the characteristic glycosylation pattern, suggesting that
these posttranslational modifications are essential for function.
Furthermore, evolutionary analysis of a region of 53 amino acids of fish,
frog, rat, mouse, and human olfactomedins indicates that an ancestral
olfactomedin gene arose before the evolution of terrestrial vertebrates and
evolved independently in teleost, amphibian, and mammalian lineages.
Indeed, a distant olfactomedin homolog was identified in Caenorhabditis
elegans. Although the amino acid sequence of this invertebrate protein is
longer and highly divergent compared with its vertebrate homologs, the
protein from C. elegans shows remarkable similarities in terms of conserved
motifs and posttranslational modification sites. Six universally conserved
motifs were identified, and five of these are clustered in the carboxyl
terminal half of the protein. Sequence comparisons indicate that evolution
of the N-terminal half of the molecule involved extensive insertions and
deletions; the C-terminal segment evolved mostly through point mutations,
at least during vertebrate evolution. The widespread occurrence of
olfactomedin among vertebrates and invertebrates underscores the notion
that this protein has a function of universal importance. Furthermore,
extensive modification of its N-terminal half and the acquisition of a
C-terminal SDEL endoplasmic-reticulum- targeting sequence may have enabled
olfactomedin to adopt new functions in the mammalian central nervous
system.
相似文献
189.
The molecular organization of the beta-globin complex of the deer mouse, Peromyscus maniculatus 总被引:1,自引:0,他引:1
Padgett RW; Loeb DD; Snyder LR; Edgell MH; Hutchison CA d 《Molecular biology and evolution》1987,4(1):30-45
Recombinant DNA clones have been isolated that contain 80 kb of the
beta-globin complex from the deer mouse, Peromyscus maniculatus.
Comparisons of this complex with that from the laboratory mouse, Mus
domesticus (with an order 5'-Hbby, Hbb-bhO, Hbb-bhl, Hbb-bh2, Hbb-bh3,
Hbb-bl, Hbb-b2 3') highlight organizational trends in the beta-globin
complex since the two species diverged. Unlike other mammals studied thus
far, the deer mouse possesses three adult genes. Partial sequence analysis
indicates that each of the three adult genes is intact and hence may be
functional. Hybridization of one of the two Mus pseudogenes, Hbb-bh3, to
genomic blots from Peromyscus reveals that it has a homologous counterpart
in Peromyscus. Homologous genes to the two gamma-like Mus genes, Hbb-bhO
and Hbb-bhl, are also found in Peromyscus. The strong hybridization between
the Hbb-bhl genes and significant nucleotide similarity between the Hbb-bhO
genes suggest that both pairs are important for the ontogeny of these mice
although no known product has been identified for the Hbb-bhO genes. The
presence of Hbb-bhO and Hbb-bhl in Peromyscus suggests that the duplication
that created this related gene set occurred before the two lineages
diverged. A single gene for Hbb-y has been isolated from Peromyscus. The
adult region in Peromyscus has undergone significant divergence from the
same region in Mus, having three rather than two adult genes, the
acquisition of at least 15 kb of extra DNA relative to Mus, and possibly
the loss of the Hbb-bh2 pseudogene. The nonadult region of the complex, in
contrast, contains the same set of genes apparently distributed over the
same amount of DNA as in the Mus beta- globin complex. This observation
suggests that the embryonic region of the complex is more evolutionarily
stable than the adult region.
相似文献
190.