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21.
The objective of the present study was to explore the site of synthesis of vitellogenin (Vtg) in fresh water edible crab, Oziothelphusa senex senex. Vtg cDNA fragments were isolated from the hepatopancreas of female crabs using RT-PCR method, and the deduced amino acid sequence of O. senex senex showed more than 60% identity with other brachyuran Vtg sequences. RT-PCR analysis showed that Vtg mRNA can be detected only in hepatopancreas of female Oziothelphusa but not in other tissues including eyestalks, Y-organs, mandibular organs, thoracic ganglion, hypodermis and ovary. Antibodies were raised against vitellin purified from the ovary of O. senex senex. Immunoprecipitation analysis revealed the presence of Vtg in the hepatopancreas of vitellogenic stage I females and in the hemolymph, hepatopancreas and ovary extracts from vitellogenic stage II females but absent in hemolymph and hepatopancreas extract of males. These results suggest that Vtg is synthesized only in hepatopancreas but not in the ovaries of O. senex senex. In addition, Vtg synthesized in hepatopancreas is transported to ovary through hemolymph.  相似文献   
22.
Glucose transport into cells may be regulated by a variety of conditions, including ischemia. We investigated whether some enzymes frequently involved in the metabolic adaptation to ischemia are also required for glucose transport activation. Ischemia was simulated by incubating during 3 h H9c2 cardiomyoblasts in a serum- and glucose-free medium in hypoxia. Under these conditions 2-deoxy-d-[2,6-3H]-glucose uptake was increased (57% above control levels, p < 0.0001) consistently with GLUT1 and GLUT4 translocation to sarcolemma. Tyrosine kinases inhibition via tyrphostin had no effect on glucose transport up-regulation induced by simulated ischemia. On the other hand, chelerythrine, a broad range inhibitor of protein kinase C isoforms, and rottlerin, an inhibitor of protein kinase C delta, completely prevented the stimulation of the transport rate. A lower activation of hexose uptake (19%, p < 0.001) followed also treatment with Gö6976, an inhibitor of conventional protein kinases C. Finally, PD98059-mediated inhibition of the phosphorylation of ERK 1/2, a downstream mitogen-activated protein kinase (MAPK), only partially reduced the activation of glucose transport induced by simulated ischemia (31%, p < 0.01), while SB203580, an inhibitor of p38 MAPK, did not exert any effect. These results indicate that stimulation of protein kinase C delta is strongly related to the up-regulation of glucose transport induced by simulated ischemia in cultured cardiomyoblasts and that conventional protein kinases C and ERK 1/2 are partially involved in the signalling pathways mediating this process.  相似文献   
23.
Chemical aspects of siderophore mediated iron transport   总被引:8,自引:7,他引:8  
In this mini-review we describe selected aspects of the coordination chemistry relevant to siderophore mediated iron transport and bioavailability. Specific emphasis is placed on a discussion of in vitro kinetic and thermodynamic data that are relevant to elucidating possible in vivo mechanisms for environmental iron acquisition by microbial cells.  相似文献   
24.
For many cancers, the lack of potency and the toxicity of current drugs limits the dose achievable in patients and the efficacy of treatment. Among them, retinoblastoma is a rare cancer of the eye for which better chemotherapeutic options are needed. Combination therapy is a compelling approach to enhance the efficacy of current treatment, however clinical trials to test rationally designed combinations of approved drugs are slow and expensive, and limited by our lack of in-depth knowledge of drug specificity. Since many patients already turn to nutraceuticals in hopes of improving their condition, we hypothesized that certain approved drugs could potentially synergize with widely consumed supplements. Following this hypothesis, we devised an alternative screening strategy aimed at taking advantage of a bait compound such as a nutraceutical with potential therapeutic benefits but low potency, by screening chemical libraries for approved drugs that synergize with this companion effector. As a proof of concept, we sought to identify approved drugs with synergetic therapeutic effects toward retinoblastoma cells in combination with the antioxidant resveratrol, popular as a supplement. We systematically tested FDA-approved drugs and known bioactives seeking to identify such pairs, which led to uncovering only a few additive combinations; but to our surprise, we identified a class of anticancer drugs widely used in the clinic whose therapeutic effect is antagonized with resveratrol. Our observations could explain in part why some patients do not respond well to treatment. Our results validate this alternative approach, and we expect that our companion effector strategy could significantly impact both drug discovery and the nutraceutical industry.  相似文献   
25.
Previously, we showed that isolated stem cells from midguts of Heliothis virescens can be induced to multiply in response to a multiplication protein (MP) isolated from pupal fat body, or to differentiate to larval types of mature midgut cells in response to either of 4 differentiation factors (MDFs) isolated from larval midgut cell-conditioned medium or pupal hemolymph. In this work, we show that the responses to MDF-2 and MP in H. virescens stem cells decayed at different time intervals, implying that the receptors or response cascades for stem cell differentiation and multiplication may be different. However, the processes appeared to be linked, since conditioned medium and MDF-2 prevented the action of MP on stem cells; MP by itself appeared to repress stem cell differentiation. Epidermal growth factor, retinoic acid, and platelet-derived growth factor induced isolated midgut stem cells of H. virescens and Lymantria dispar to multiply and to differentiate to mature midgut cells characteristic of prepupal, pupal, and adult lepidopteran midgut epithelium, and to squamous-like cells and scales not characteristic of midgut tissue instead of the larval types of mature midgut epithelium induced by the MDFs. Midgut stem cells appear to be multipotent and their various differentiated fates can be influenced by several growth factors.  相似文献   
26.
著: 《生物信息学》2019,26(5):8-12
随着全球建造业向数字化全面转型,建筑信息模型(BIM)的教学将是未来几年风景园林设计与实施的重要主题。介绍了风景园林专业BIM的教学方法和数字化竖向设计及其应用在BIM场地设计项目中的重要性。数字化竖向设计是实现BIM的途径。风景园林教育必须在其教学中讲解BIM建模方法和过程。  相似文献   
27.
Generation of superoxide anion by the multiprotein complex NADPH phagocyte oxidase is accompanied by extensive phosphorylation of its 47-kDa protein component, p47(phox), a major cytosolic component of this oxidase. Protein kinase C zeta (PKC zeta), an atypical PKC isoform expressed abundantly in human polymorphonuclear leukocytes (PMN), translocates to the PMN plasma membrane upon stimulation by the chemoattractant fMLP. We investigated the role of PKC zeta in p47(phox) phosphorylation and in superoxide anion production by human PMN. In vitro incubation of recombinant p47(phox) with recombinant PKC zeta induced a time- and concentration-dependent phosphorylation of p47(phox) with an apparent K(m) value of 2 microM. Phosphopeptide mapping analysis of p47(phox) showed that PKC zeta phosphorylated fewer selective sites in comparison to "conventional" PKCs. Serine 303/304 and serine 315 were identified as targets of PKC zeta by site-directed mutagenesis. Stimulation of PMN by fMLP induced a rapid and sustained plasma membrane translocation of PKC zeta that correlated to that of p47(phox). A cell-permeant-specific peptide antagonist of PKC zeta inhibited both fMLP-induced phosphorylation of p47(phox) and its membrane translocation. The antagonist also inhibited the fMLP-induced production of oxidant (IC(50) of 10 microM), but not that induced by PMA. The inhibition of PKC zeta expression in HL-60 neutrophil-like cells using antisense oligonucleotides (5 and 10 microM) inhibited fMLP-promoted oxidant production (27 and 50%, respectively), but not that induced by PMA. In conclusion, p47(phox) is a substrate for PKC zeta and participates in the signaling cascade between fMLP receptors and NADPH oxidase activation.  相似文献   
28.
When appropriately stimulated, monocytes are able to initiate blood coagulation through the membrane expression of tissue factor. This procoagulant activity is thought to play a role in activating coagulation in response to inflammatory stimuli in vivo. We found that pentoxifylline, a methylxanthine derivative already reported to regulate some monocyte functions, inhibits the procoagulant activity developed by monocytes in vitro in response to endotoxin. This effect was accompanied by an early increase in intracellular levels of cyclic AMP and was mimicked by compounds that induce an increase in cyclic AMP levels. These results suggest that the suppressive effect of pentoxifylline occurs at least in part via an increase in intracellular cyclic AMP levels.  相似文献   
29.
COVID-19 or SARS-CoV-2 infection can lead to severe acute respiratory distress syndrome/pneumonia with features of cytokine storm reminiscent of secondary hemophagocytic lymphohistiocytosis (HLH), which can be diagnosed by the calculated HScore. Recent reports have suggested favorable responses to the interleukin-1 receptor antagonist, anakinra in patients with COVID-19 associated secondary HLH. In our single institution study, we compared 14 COVID-19 cytokine storm patients with 10 secondary HLH patients seen immediately prior to the pandemic (non-COVID-19), to determine whether diagnostic features of secondary HLH were typically seen in COVID-19 patients presenting with cytokine storm. Although most of our COVID-19 patients did not fulfill diagnostic criteria for HLH, we hypothesize that identification of HLH may relate to the severity or timing of cytokine release. Based on our observations, we would suggest distinguishing between cytokine release syndrome and secondary HLH, reserving the latter term for cases fulfilling diagnostic criteria.Impact statementSevere COVID-19 associated pneumonia and acute respiratory distress syndrome has recently been described with life-threatening features of cytokine storm and loosely referred to as hemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS). Although a recent report indicated favorable responses to the interleukin-1 receptor antagonist, anakinra in eight patients with COVID-19 secondary HLH diagnosed using the HScore calculation, others have suggested that the diagnosis of secondary HLH is uncommon and that the use of the HScore has limited value in guiding immunomodulatory therapy for COVID-19. Here, we provide additional perspective on this important controversy based upon comparisons between 14 COVID-19 cytokine storm patients and 10 secondary HLH patients seen immediately prior to the pandemic. We hypothesize that identification of HLH may relate to the severity or timing of cytokine release and suggest distinguishing between cytokine release syndrome and secondary HLH, reserving the latter term for cases fulfilling diagnostic criteria.  相似文献   
30.
Journal of Ethology - Animals emit predator-elicited calls in response to potential predation threats. These vocalizations induce a variety of anti-predator behaviors in conspecific receivers...  相似文献   
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