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排序方式: 共有141条查询结果,搜索用时 31 毫秒
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Sergey A. Siletsky Tewfik Soulimane Ilya Belevich Robert B. Gennis Mårten Wikström 《BBA》2021,1862(9):148450
Cytochrome ba3 from Thermus thermophilus belongs to the B family of heme-copper oxidases and pumps protons across the membrane with an as yet unknown mechanism. The K channel of the A family heme-copper oxidases provides delivery of a substrate proton from the internal water phase to the binuclear heme-copper center (BNC) during the reductive phase of the catalytic cycle, while the D channel is responsible for transferring both substrate and pumped protons. By contrast, in the B family oxidases there is no D-channel and the structural equivalent of the K channel seems to be responsible for the transfer of both categories of protons. Here we have studied the effect of the T315V substitution in the K channel on the kinetics of membrane potential generation coupled to the oxidative half-reaction of the catalytic cycle of cytochrome ba3. The results suggest that the mutated enzyme does not pump protons during the reaction of the fully reduced form with molecular oxygen in a single turnover. Specific inhibition of proton pumping in the T315V mutant appears to be a consequence of inability to provide rapid (τ ~ 100 μs) reprotonation of the internal transient proton donor(s) of the K channel. In contrast to the A family, the K channel of the B-type oxidases is necessary for the electrogenic transfer of both pumped and substrate protons during the oxidative half-reaction of the catalytic cycle. 相似文献
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Rahmani Behrouz Ghashghayi Elham Zendehdel Morteza Khodadadi Mina Hamidi Behnam 《International journal of peptide research and therapeutics》2021,27(4):2349-2370
International Journal of Peptide Research and Therapeutics - Appetite is controlled by a complex system of central and peripheral signals interacting to modulate the ingestion response. Several... 相似文献
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Mehrdad Hamidi Abdolhossein Zarrin Mahshid Foroozesh 《Critical reviews in biotechnology》2013,33(3):111-127
ABSTRACTInterferons, IFNs, are among the most widely studied and clinically used biopharmaceuticals. Despite their invaluable therapeutic roles, the widespread use of IFNs suffers from some inherent limitations, mainly their relatively short circulation lifespan and their unwanted effects on some non-target tissues. Therefore, both these constraints have become the central focus points for the research efforts on the development of a variety of novel delivery systems for these therapeutic agents with the ultimate goal of improving their therapeutic end-points. Generally, the delivery systems currently under investigation for IFNs can be classified as particulate delivery systems, including micro- and nano-particles, liposomes, minipellets, cellular carriers, and non-particulate delivery systems, including PEGylated IFNs, other chemically conjugated IFNs, immunoconjugated IFNs, and genetically conjugated IFNs. All these strategies and techniques have their own possibilities and limitations, which should be taken into account when considering their clinical application. In this article, currently studied delivery systems/techniques for IFN delivery have been reviewed extensively, with the main focus on the pharmacokinetic consequences of each procedure. 相似文献
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OBJECTIVE: To establish a polymerase chain reaction (PCR)-based clonality assay for archival cervical smears and examine its value in the detection of cervical intraepithelial neoplasia (CIN) and prediction of its clinical behavior. STUDY DESIGN: Dyskaryotic cells were microdissected from archival cervical smears of 33 cases and subjected to PCR-based clonality analysis of the androgen receptor gene. High-risk HPV subtypes were screened by PCR. RESULTS: Monoclonal patterns were found in 9/9 CIN 3 and 15/21 CIN 2, while polyclonal patterns were observed in the remaining 6 CIN 2 and 3/3 CIN 1. All patients with monoclonal CIN lesions, including 15 CIN 2, showed recurrence of the disease despite treatment. The original CIN 2 and recurrent CIN lesion in each of the 6 examined cases showed the same monoclonal pattern, suggesting a clonal link. In contrast, the patients with polyclonal CIN 1 or 2 became negative and remained disease free. High-risk HPV subtypes were found in all monoclonal CIN lesions, including 9 CIN 3 and 15 CIN 2, and in 4/6 polyclonal CIN 2 but not in CIN 1 lesions. CONCLUSION: Clonality analysis of cervical smears is potentially valuable in the identification of true neoplastic cells and prediction of clinical behavior of CIN 2 lesions. 相似文献
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The effects of long-term ingestion of fluoxetine on fertility were investigated in Sprague-Dawley male rats. Adult male rats were exposed to fluoxetine at a concentration of 200 mg/kg for 60 days. Long-term ingestion of fluoxetine for 60 days caused a great decrease in spermatogenesis in seminiferous tubules of the testes. Sperm motility and density were also significantly reduced in cauda epididymides and testes of the treated group. The weights of reproductive organs (testes, epididymides, ventral prostrate and seminal vesicle) were decreased considerably. The hormonal assay also showed significant decrease in testosterone levels and FSH levels. Testicular cell population dynamics also demonstrated a decrease in the number of both primary and secondary spermatocystes and spermatids in the treatment group. The number of female rats impregnated by male rats on long-term fluoxetine diet had decreased. The number of implantations and the number of viable fetuses were also notably decreased in female rats impregnated by male rats ingested fluoxetine. Fluoxetine caused a slight decrease in body weight, when initial and final body weights were compared in the experimental groups. Levels of ALT and AST were found to be significantly increased in the treated group when compared to the control. Histometery of reproductive organs confirmed these results. In conclusion, these results confirm that the long-term fluoxetine ingestion produce adverse effects on fertility and reproductive system in adult male rat. Thus, it would be of great interest to investigate the impact via long -term treatment with fluoxetine in male human fertility. 相似文献
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Loessner H Endmann A Leschner S Westphal K Rohde M Miloud T Hämmerling G Neuhaus K Weiss S 《Cellular microbiology》2007,9(6):1529-1537
We have used Salmonella enterica serovar Typhimurium (S. typhimurium) which are able to colonize tumours besides spleen and liver. Bacteria were equipped with constructs encoding green fluorescent protein or luciferase as reporters under control of the promoter PBAD that is inducible with L-arabinose. Reporter genes could be induced in culture but also when the bacteria resided within the mouse macrophages J774A.1. More important, strong expression of reporters by the bacteria could be detected in mice after administration of L-arabinose. This was especially pronounced in bacteria colonizing tumours. Histology demonstrated that the bacteria had accumulated in and close to necrotic areas of tumours. Bacterial gene induction was observed in both regions. PBAD is tightly controlled also in vivo because gene E of bacteriophage PhiX174 could be introduced as inducible suicide gene. The possibility to deliberately induce genes in bacterial carriers within the host should render them extremely powerful tools for tumour therapy. 相似文献
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Sayyed A Hamidi Richard Z Lin Anthony M Szema Sergey Lyubsky Ya Ping Jiang Sami I Said 《Respiratory research》2011,12(1):141