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排序方式: 共有217条查询结果,搜索用时 11 毫秒
41.
A nitric oxide synthesis inhibitor decreased prostaglandin production in rat mesenteric vasculature 总被引:1,自引:0,他引:1
Masayoshi Soma Yoichi Izumi Yoshiyasu Watanabe Katsuo Kanmatsuse 《Prostaglandins & other lipid mediators》1996,51(3):225-232
Endothelial cells synthesize and release nitric oxide (NO) and prostacyclin (PGI2) which are involved in the regulation o f vascular tone and blood pressure. Our objective was to evaluate the effects of inhibiting NO synthesis on vascular prostaglandin (PG) and cyclic nucleotide production, as well as the pressor response to norepinephrine (NE). Isolated mesenteric arterial beds were perfused with Krebs-Henseleit solution containing 100 μM NG-monomethyl-L-arginine (L-NMMA), 100 μM L-arginine (LA), or vehicle. After a 30 min equilibration 0.1, 0.5, 1, or 5 μM NE was infused into the superior mesenteric artery and the perfusion pressure was monitored. The basal perfusion pressure did not differ significantly between groups. The pressure-response curve was shifted to the right in the L-NMMA group vs. the LA and control groups. Perfusion was similarly performed with a Krebs-Henseleit solution containing 100 μM L-NMMA, LA, D-arginine, or vehicle. Perfusates were collected before and after NE infusion for the measurement of PGE2, 6-keto-PGF1α, TxB2, cAMP, and cGMP. In the L-NMMA group the release of PGE2 and 6-keto-PGF1α was decreased, and the release of cGMP was prevented. Production of cAMP did not differ between the four groups before NE infusion, and NE increased cAMP release in the L-NMMA group and controls. The results indicate that inhibition of NO synthesis by L-NMMA enhanced the pressor response to NE, possibly mediated by the decreased cGMP and PGI2 production in resistance vessels. 相似文献
42.
Kenji Hiromatsu Jun Usami Yoshiyasu Aoki Masahiko Makino Yasunobu Yoshikai 《Microbiology and immunology》1997,41(3):221-227
We reported previously that CD4+ T cells and B cells in mice with retrovirus-induced murine acquired immunodeficiency syndrome (MAIDS) caused by LP-BM5 murine leukemia virus (MuLV) mixtures increased the expression of Fas antigen (Fas) during progression of the disease. However, the contribution of the Fas/Fas ligand (Fas L) system to the pathogenesis of MAIDS remained unknown. Here, we examined the susceptibility of C57BL/6 (B6) lpr/lpr mice, which has been reported to be defective for the expression of Fas, to MAIDS. We found that the Thy 1.2? CD4 T cells and IgK dull B220+ cells, which are characteristic of MAIDS, increased after the inoculation of LP-BM5 MuLV in B6 lpr/lpr mice. B22+ TCR αβ T cells, unique to lupus prone mice, also increased in the B6 lpr/lpr mice after infection. CD4+ B220+ TCR αβ T cells increased profoundly among the B220+ TCR αβ T cells from LP-BM5 MuLV-infected B6 lpr/lpr mice, while the B220+ TCR αβ T cells observed in non-infected B6 lpr/lpr mice were largely of the CD4? CD8? phenotype. A DNA PCR analysis of the LP-BM5 MuLV-infected B6 lpr/lpr mice revealed the genome integration of defective LP-BM5 virus, further confirming that MAIDS is inducible to B6 lpr/lpr mice. LP-BM5 MuLV-infected lpr/lpr mice died within 3 months, while MAIDS-infected B6 +/+ mice usually died within 5 to 6 months, and B6 lpr/lpr mice not infected with LP-BM5 MuLV lived more than 6 months. Taken together, these results suggest that MAIDS is inducible independently with functional Fas expression and the possibility of accelerated progression of murine AIDS and lpr-associated autoimmune disease in B6 lpr/lpr mice infected with LP-BM5 MuLV. 相似文献
43.
A new sesquiterpene dialdehyde, plagiochilal B, isolated from the liverwort Plagiochila fruticosa exhibits not only acceleration of neurite sprouting but also enhancement of choline acetyltransferase activity on a neuronal cell culture of fetal rat cerebral hemisphere at 10−5 M. Additionally, two new secoaromadendranes, plagiochilines J and K were isolated. The structures of the new secoaromadendrane-type sesquiterpenes were established by extensive 2D NMR data and chemical correlation with plagiochiline A. 相似文献
44.
Uchida M Harada T Enkhtuya J Kusumoto A Kobayashi Y Chiba S Shyaka A Kawamoto K 《Biochemical and biophysical research communications》2012,421(2):323-328
Bacillus anthracis spores germinate to vegetative forms in host cells, and produced fatal toxins. A toxin-targeting prophylaxis blocks the effect of toxin, but may allow to grow vegetative cells which create subsequent toxemia. In this study, we examined protective effect of extractable antigen 1 (EA1), a major S-layer component of B. anthracis, against anthrax. Mice were intranasally immunized with recombinant EA1, followed by a lethal challenge of B. anthracis spores. Mucosal immunization with EA1 resulted in a significant level of anti-EA1 antibodies in feces, saliva and serum. It also delayed the onset of anthrax and remarkably decreased the mortality rate. In addition, the combination of EA1 and protective antigen (PA) protected all immunized mice from a lethal challenge with B. anthracis spores. The numbers of bacteria in tissues of EA1-immunized mice were significantly decreased compared to those in the control and PA alone-immunized mice. Immunity to EA1 might contribute to protection at the early phase of infection, i.e., before massive multiplication and toxin production by vegetative cells. These results suggest that EA1 is a novel candidate for anthrax vaccine and provides a more effective protection when used in combination with PA. 相似文献
45.
Formation of 5-formyl-2'-deoxycytidine from 5-methyl-2'-deoxycytidine in duplex DNA by Fenton-type reactions and gamma-irradiation. 总被引:1,自引:0,他引:1 下载免费PDF全文
N Murata-Kamiya H Kamiya N Karino Y Ueno H Kaji A Matsuda H Kasai 《Nucleic acids research》1999,27(22):4385-4390
5-methyl-2'-deoxycytidine (5-Me-dC) is formed by the enzymatic methylation of dC, primarily in CpG sequences in DNA, and is involved in the regulation of gene expression. In the present study, 5-Me-dC and double-stranded DNA fragments containing 5-Me-dC were either gamma-irradiated or aerobically treated with Fenton-type reagents, Fe(II)-EDTA, Fe(II)-nitrilotriacetic acid, Fe(III)-EDTA-H(2)O(2)-catechol or ascorbic acid-H(2)O(2) under neutral conditions. The formation of 5-formyl-2'-deoxycytidine (5-CHO-dC) was observed upon treatment of both 5-Me-dC and DNA fragments containing 5-Me-dC. The yields of 5-CHO-dC from 5-Me-dC and those of 5-formyl-2'-deoxyuridine from dT were comparable. These results suggest that 5-Me-dC in DNA is as susceptible to oxidation as dT in cells, and raise the possibility that 5-CHO-dC may contribute to the high mutagenic rate observed in CpG sequences in genomic DNA. 相似文献
46.
Sexual selection often favors male secondary sexual traits, although in some cases the elaborate traits incur costs to the males with respect to natural selection. Males of the guppy Poecilia reticulata have longer tails (caudal fins) than females, and the long tails contribute to the mating success of the males through female mate choice. We examined the effect of tail length on the swimming performance of male and female guppies. In a laboratory experiment, males with longer tails exhibited poorer swimming performance than those with shorter tails. However, this effect was not apparent in females. In addition, in a feral population, tail length of males was negatively correlated with water flow velocity in their microhabitats. Although body size of females was negatively correlated with water flow velocity in their microhabitats, tail length of females showed no significant correlation with degree of water flow. These results suggest that the long tail of male guppies incurs costs, such as a decrease in swimming performance, to the males with respect to natural selection and consequently limits their choice of habitats to those with slow water flow. 相似文献
47.
Satoko Seki Masanori Kohda Gousuke Takamoto Kenji Karino Yasuhiro Nakashima Tetsuo Kuwamura 《Journal of Ethology》2009,27(2):215-220
The occurrence of polygyny requires specific environmental conditions such as female aggregation or patchy resource distribution.
However, it is difficult to determine the factors responsible for polygyny in species in which the territories of both sexes
overlap. To overcome this, we performed female removal experiments in the polygynous triggerfish Sufflamen chrysopterum (Balistidae) in the Okinawa coral reef. Both sexes defended their territories exclusively against consexuals of the same
species, and female aggregation was absent. Each male territory included 1–3 female territories, and nonterritorial males
were significantly smaller than territorial males. Further, the body size of territorial males was positively correlated with
that of the largest female in their territories, and larger males tended to mate with more females. The results of the female
removal experiments (n = 10 females) indicated that females competed for better territories rather than larger mates. In contrast, males abandoned
the territories once the females emigrated. These results strongly suggest that males defend females rather than sites and
compete for larger and a greater numbers of females. Thus, in S. chrysopterum, female defense polygyny occurs in the absence of female aggregation. 相似文献
48.
Akinori Sato Takuro Arimura Naomasa Makita Taisuke Ishikawa Yoshiyasu Aizawa Hiroya Ushinohama Yoshifusa Aizawa Akinori Kimura 《The Journal of biological chemistry》2009,284(50):35122-35133
Long QT syndrome (LQTS) is a hereditary arrhythmia caused by mutations in genes for cardiac ion channels, including a potassium channel, KvLQT1. Inheritance of LQTS is usually autosomal-dominant, but autosomal-recessive inheritance can be observed in patients with LQTS accompanied by hearing loss. In this study, we investigated the functional alterations caused by KCNQ1 mutations, a deletion (delV595) and a frameshift (P631fs/19), which were identified in compound heterozygous state in two patients with autosomal-recessive LQTS not accompanied by hearing loss. Functional analyses showed that both mutations impaired cell surface expression due to trafficking defects. The mutations severely affected outward potassium currents without apparent dominant negative effects. It was found that delV595 impaired subunit binding, whereas P631fs/19 was retained in endoplasmic reticulum due to the newly added 19-amino acid sequence containing two retention motifs (R633GR and R646LR). This is the first report of novel mechanisms for trafficking abnormality of cardiac ion channels, providing us new insights into the molecular mechanisms of LQTS. 相似文献
49.
Yoshimi Kanie Miki Yamamoto-Hino Yayoi Karino Hiroki Yokozawa Shoko Nishihara Ryu Ueda Satoshi Goto Osamu Kanie 《PloS one》2009,4(5)
Background
A variety of N-glycans attached to protein are known to involve in many important biological functions. Endoplasmic reticulum (ER) and Golgi localized enzymes are responsible to this template-independent glycan synthesis resulting glycoforms at each asparagine residues. The regulation mechanism such glycan synthesis remains largely unknown.Methodology/Principal Findings
In order to investigate the relationship between glycan structure and protein conformation, we analyzed a glycoprotein of Drosophila melanogaster, chaoptin (Chp), which is localized in photoreceptor cells and is bound to the cell membrane via a glycosylphosphatidylinositol anchor. Detailed analysis based on mass spectrometry revealed the presence of 13 N-glycosylation sites and the composition of the glycoform at each site. The synthetic pathway of glycans was speculated from the observed glycan structures and the composition at each N-glycosylation site, where the presence of novel routes were suggested. The distribution of glycoforms on a Chp polypeptide suggested that various processing enzymes act on the exterior of Chp in the Golgi apparatus, although virtually no enzyme can gain access to the interior of the horseshoe-shaped scaffold, hence explaining the presence of longer glycans within the interior. Furthermore, analysis of Chp from a mutant (RNAi against dolichyl-phosphate α-d-mannosyltransferase), which affects N-glycan synthesis in the ER, revealed that truncated glycan structures were processed. As a result, the distribution of glycoforms was affected for the high-mannose-type glycans only, whereas other types of glycans remained similar to those observed in the control and wild-type.Conclusions/Significance
These results indicate that glycan processing depends largely on the backbone structure of the parent polypeptide. The information we obtained can be applied to other members of the LRR family of proteins. 相似文献50.
Mikihiro Yunoki Hiroyuki Tanaka Takeru Urayama Yuta Kanai Aya Nishida Maki Yoshikawa Yuji Ohkubo Yoshiyasu Kawabata Katsuro Hagiwara Kazuyoshi Ikuta 《Biologicals》2010,38(2):311-313
The evaluation of the removal efficacy during manufacturing is important for the risk assessment of plasma products with respect to possible contamination by infectious prions, as recently reported in several papers on the potential for prion transmission through plasma products. Here, we evaluated a virus removal filter which has 15 nm pores. An antithrombin sample immediately prior to nano-filtration was spiked with prion material prepared in two different ways. The removal (log reduction factor) of prion infectivity using animal bioassays was ≥4.72 and 4.00 in two independent filtrations. However, infectivity was detected in both the pellet and supernatant following ultracentrifugation of the 15 nm filtered samples, indicating difficulty in complete removal. The data supports the conclusion that a certain amount of infectious prion protein is present as a smaller and/or soluble form (less than ~15 nm in diameter). 相似文献