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121.
We present the X-ray structure of the RuvA-RuvB complex, which plays a crucial role in ATP-dependent branch migration. Two RuvA tetramers form the symmetric and closed octameric shell, where four RuvA domain IIIs spring out in the two opposite directions to be individually caught by a single RuvB. The binding of domain III deforms the protruding beta hairpin in the N-terminal domain of RuvB and thereby appears to induce a functional and less symmetric RuvB hexameric ring. The model of the RuvA-RuvB junction DNA ternary complex, constructed by fitting the X-ray structure into the averaged electron microscopic images of the RuvA-RuvB junction, appears to be more compatible with the branch migration mode of a fixed RuvA-RuvB interaction than with a rotational interaction mode.  相似文献   
122.
Secretin, a 27-amino acid neuropeptide, is a member of the glucagon/secretin/vasoactive intestinal polypeptide (VIP) superfamily of amphipathic peptides that elicits transient vasodilation in vivo. The purpose of this study was to determine whether association of human secretin with sterically stabilized phospholipid micelles (SSM) amplifies the vasorelaxant effects of the peptide in the peripheral microcirculation in vivo. We found that secretin in saline evoked significant concentration-dependent vasodilation in the intact hamster cheek pouch microcirculation (P < 0.05). This response was potentiated and prolonged significantly when secretin was associated with SSM (P < 0.05). Vasodilation evoked by secretin in saline and secretin in SSM was abrogated by VIP(10-28), a VIP receptor antagonist, but not by PACAP(6-38), a PACAP receptor antagonist, or Hoe140, a selective bradykinin B(2) receptor antagonist. Collectively, these data indicate that self-association of human secretin with SSM significantly amplifies peptide vasoreactivity in the intact peripheral microcirculation through activation of VIP receptors. We suggest that the vasoactive effects of human secretin in vivo are, in part, phospholipid-dependent.  相似文献   
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124.
Adrenomedullin is a potent vasodilator peptide secreted by vascular endothelial and smooth muscle cells. Adrenomedullin stimulates the proliferation of quiescent rat vascular smooth muscle cells (VSMCs) via p42/p44 ERK/MAP kinase activation. Recently, receptor-activity-modifying proteins (RAMPs) have been shown to transport calcitonin-receptor-like-receptor (CRLR) to the cell surface to present either as CGRP receptor or adrenomedullin receptor. We investigated whether adrenomedullin acts as an autocrine/paracrine growth factor for cultured rat VSMCs and whether coexpressions of RAMP isoform and CRLR may mediate p42/p44 ERK/MAP kinase activation by adrenomedullin. Adrenomedullin dose-dependently stimulated the proliferation of quiescent rat VSMCs, and this effect was inhibited by an adrenomedullin receptor antagonist, a MAP kinase kinase inhibitor and phosphatidylinositol 3-kinase inhibitors. Addition of either CGRP(8-37) or anti-adrenomedullin antibody to exponentially growing rat VSMCs inhibited the serum-induced cell proliferation, suggesting its role as an autocrine/paracrine growth factor. Cotransfection of RAMP2 or RAMP3 with CRLR into rat VSMCs potentiated activation of cAMP activity, but not of p42/p44 ERK/MAP kinase activity in response to adrenomedullin. Our results suggest that adrenomedullin is an autocrine/paracrine growth factor for rat VSMCs via p42/p44 ERK/MAP kinase and phosphatidylinositol 3-kinase pathways and that it is not mediated by human RAMP-CRLR receptors.  相似文献   
125.
Both the role and source of tumor necrosis factor (TNF-alpha) in lipopolysaccharide (LPS)-induced nasal inflammation were investigated using TNF-alpha gene deficient (TNF-alpha -/-) mice and chimeric mice that are TNF-alpha gene deficient only in bone marrow-derived cells. In the present study, intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) mRNA expression levels in the nasal mucosa were significantly decreased following intranasal instillation of LPS in TNF-alpha gene deficient mice compared to those in wild type mice. In contrast, ICAM-1 and VCAM-1 mRNA expressions were not significantly decreased although TNF-alpha mRNA expression was dramatically decreased in TNF-alpha gene deficient bone marrow-transplanted-chimeric (TNF-alpha -/--->+/+) mice compared to those in wild type bone marrow-transplanted-control (TNF-alpha +/+-->+/+) mice. These results indicate that the elevation of TNF-alpha mRNA in the nasal mucosa is mainly originated from bone marrow-derived cells. However, even low expression of TNF-alpha at local inflammation sites is sufficient to induce the expression of adhesion molecules in acute LPS-induced experimental rhinitis.  相似文献   
126.
AIMS: The purpose of the present investigation was to assess the salivary levels of Streptococcus anginosus in periodontitis patients. METHODS AND RESULTS: The salivary levels of Strep. anginosus were assessed using real-time polymerase chain reaction (PCR). Streptococcus anginosus was detected in 28 of 37 (75.6%) of periodontitis patients and in three of the 20 (15%) healthy subjects. The mean values for bleeding on probing and probing depth in positive patients were statistically higher than those in negative patients. A significant decrease in Strep. anginosus levels was observed after periodontal treatment. CONCLUSIONS: Although the levels of Strep. anginosus are extremely low, they may reflect the status of periodontal health. SIGNIFICANCE AND IMPACT OF THE STUDY: Real-time PCR is a useful method for obtaining the relative quantities of Strep. anginosus from saliva samples and for monitoring the effect of therapy.  相似文献   
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128.
Laboratory experiments were carried out to investigate byssal thread production by the intertidal mytilid mussel Hormomya mutabilis in response to effluent from the predatory crab Eriphia smithii and the starfish Coscinasterias acutispina. During the early period of the experiment, large H. mutabilis exposed to crab effluent produced a significantly smaller number of functional byssal threads than mussels in crab-free water. No significant difference in the diameter of threads produced in the two treatments was detected. The number of functional byssal threads produced by small H. mutabilis exposed to crab effluent did not differ significantly from that of mussels in crab-free water. However, small H. mutabilis exposed to crab effluent tended to discard fewer byssal bundles, that is, they shifted their attaching sites less frequently than similar mussels in crab-free water. In the presence of waterborne cues from the crab, H. mutabilis tended to reduce both the secretion of byssal threads and movement across the substratum. No significant differences in behaviour were observed between large mussels exposed to effluent from the starfish and those unexposed. The adaptive significance of the responses shown by H. mutabilis is discussed in terms of protection against predators differing in foraging behaviour. Electronic Publication  相似文献   
129.
AIM: The roles of adrenomedullin (AM) in body fluid balance under general anesthesia were investigated. METHODS: Time course changes in plasma osmolality, AM, arginine vasopressin (AVP), and urinary aquaporin 2 (AQP2) in 17 patients undergoing abdominal surgery under general anesthesia were examined. RESULTS: Increases in plasma AM levels were observed in parallel with increases in the levels of urinary AQP2/creatinine (Cr) before induction and 90 and 180 min after initiation of anesthesia. Significant correlations between plasma AM and urinary AQP2/Cr (r = 0.62, p < 0.0001) as well as urinary AVP/Cr and AQP2/Cr (r = 0.60, p < 0.0001) were uncovered. Multivariate stepwise analysis identified plasma AM as the critical independent factor affecting urinary AQP2/Cr level. CONCLUSION: A novel correlation of AM and AQP2 which overlays an AVP-AQP2 system may play a key role in fluid homeostasis during general anesthesia.  相似文献   
130.
It was found that the partially purified beta-ketoacyl-ACP synthase of Bacillus insolitus did not require the addition of FabD (malonyl-CoA:ACP transacylase, MAT) for the activity assay. This study therefore examined the necessity of FabD protein for in vitro branched-chain fatty acid (BCFA) biosynthesis by crude fatty acid synthetases (FAS) of Bacilli. To discover the involvement of FabD in the BCFA biosynthesis, the protein was removed from the crude FAS by immunoprecipitation. The His-tag fusion protein FabD of Bacillus subtilis was expressed in Escherichia coli and used for the preparation of antibody. The rabbit antibody raised against the expressed fusion protein specifically recognized the FabD in the crude FAS of B. subtilis. Evaluation of the efficacy of the immunoprecipitation showed that a trace of FabD protein was present in the antibody-treated crude FAS. However, this complete removal of FabD from the crude FAS did not abolish its BCFA biosynthesis, but only reduced the level to 50-60% of the control level for acyl-CoA primer and to 80% for alpha-keto-beta-methylvalerate primer. Furthermore, the FabD concentration did not necessarily correlate with the MAT specific activity in the enzyme fractions, suggesting the presence of another enzyme source of MAT activity. This study, therefore, suggests that FabD is not the sole enzyme source of MAT for in vitro BCFA biosynthesis, and implies the existence of a functional connection between fatty acid biosynthesis and another metabolic pathway.  相似文献   
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