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91.
Kin Sing Lam Jacqueline Mattei Salvatore Forenza 《Journal of industrial microbiology & biotechnology》1989,4(2):105-108
Summary A new antitumor antibiotic named rebeccamycin was isolated from fermentations of an actinomycete,Saccharothrix aerocolonigenes. A defined medium was developed to study the regulation of synthesis of rebeccamycin byS. aerocolonigenes. In glucose medium formation of rebeccamycin was detected only after glucose was depleted. Examination of eleven different carbon sources revealed that carbon catabolite regulation is a major control mechanism for rebeccamycin production. 相似文献
92.
Adiponectin Mediates the Metabolic Effects of FGF21 on Glucose Homeostasis and Insulin Sensitivity in Mice 总被引:1,自引:0,他引:1
93.
Can Chen Yi Wang Sally S. L. Goh Jing Yang Dang Hoang Lam Yukti Choudhury Felix Chang Tay Shouhui Du Wee Kiat Tan Yovita Ida Purwanti Weimin Fan Shu Wang 《Journal of neurochemistry》2013,126(3):318-330
The breakthrough in derivation of human‐induced pluripotent stem cells (hiPSCs) provides an approach that may help overcome ethical and allergenic challenges posed in numerous medical applications involving human cells, including neural stem/progenitor cells (NSCs). Considering the great potential of NSCs in targeted cancer gene therapy, we investigated in this study the tumor tropism of hiPSC‐derived NSCs and attempted to enhance the tropism by manipulation of biological activities of proteins that are involved in regulating the migration of NSCs toward cancer cells. We first demonstrated that hiPSC‐NSCs displayed tropism for both glioblastoma cells and breast cancer cells in vitro and in vivo. We then compared gene expression profiles between migratory and non‐migratory hiPSC‐NSCs toward these cancer cells and observed that the gene encoding neuronal nitric oxide synthase (nNOS) was down‐regulated in migratory hiPSC‐NSCs. Using nNOS inhibitors and nNOS siRNAs, we demonstrated that this protein is a relevant regulator in controlling migration of hiPSC‐NSCs toward cancer cells, and that inhibition of its activity or down‐regulation of its expression can sensitize poorly migratory NSCs and be used to improve their tumor tropism. These findings suggest a novel application of nNOS inhibitors in neural stem cell‐mediated cancer therapy. 相似文献
94.
Photoreactions of cytochrome b6 have been studied using resolved chloroplast electron-transfer complexes. In the presence of Photosystem (PS) II and the cytochrome b6-f complex, photoreduction of the cytochrome can be observed. No soluble components are required for this reaction. Cytochrome b6 photoreduction was found to be inhibited by quinone analogs, which inhibit at the Rieske iron-sulfur center of the cytochrome complex, by the addition of ascorbate and by depletion of the Rieske center and bound plastoquinone from the cytochrome complex. Photoreduction of cytochrome b6 can also be demonstrated in the presence of the cytochrome complex and PS I. This photoreduction requires plastocyanin and a low-potential electron donor, such as durohydroquinone. Cytochrome b6 photoreduction in the presence of PS I is inhibited by quinone analogs which interact with the Rieske iron-sulfur center. These results are discussed in terms of a Q-cycle mechanism in which plastosemiquinone serves as the reductant for cytochrome b6 via an oxidant-induced reductive pathway. 相似文献
95.
Topography of the Protein Complexes of the Chloroplast Thylakoid Membrane : Studies of Photosystem II using Pronase Digestion and Chemical Labeling 下载免费PDF全文
The accessibility of various Photosystem II (PSII)-associated polypeptides to the protease pronase and the chemical modifier trinitrobenzene-sulfonic acid (TNBS) has been investigated. Three polypeptides with apparent molecular weight of 32, 21, and 16 kilodaltons, known to be associated with O2 evolution, are all resistant to pronase digestion and TNBS labeling in intact thylakoids. All the polypeptides in the isolated PSII preparation were labeled with TNBS while a different pattern of labeling was observed when the PSII complex was isolated from TNBS-modified thylakoids. Attempts to prepare PSII particles from pronase-treated thylakoids using the Triton X-100 solubilization method were unsuccessful. Pronase-treated thylakoids were probed with antisera against the chlorophyll proteins of PSII using immunoblotting techniques. This allowed for a positive identification of proteolytic fragments from the respective proteins. The results are discussed in relation to the transmembrane organization of PSII in spinach thylakoids. 相似文献
96.
Jon T Giles Moyses Szklo Wendy Post Michelle Petri Roger S Blumenthal Gordon Lam Allan C Gelber Robert Detrano William W Scott Jr Richard A Kronmal Joan M Bathon 《Arthritis research & therapy》2009,11(2):R36
Introduction
Although cardiovascular morbidity and mortality are increased in rheumatoid arthritis, little is known about the burden of subclinical coronary atherosclerosis in these patients.Methods
Using computed tomography, coronary artery calcification was measured in 195 men and women with rheumatoid arthritis aged 45 to 84 years without clinical cardiovascular disease and compared with 1,073 controls without rheumatoid arthritis enrolled in the Baltimore cohort of the Multi-Ethnic Study of Atherosclerosis.Results
The prevalence of coronary calcification (Agatston score > 0) was significantly higher in men, but not women, with rheumatoid arthritis after adjusting for sociodemographic and cardiovascular risk factors (prevalence ratio = 1.19; P = 0.012). Among participants with prevalent calcification, those with rheumatoid arthritis had adjusted mean Agatston scores 53 units higher than controls (P = 0.002); a difference greater for men than women (P for interaction = 0.017). In all analyses, serum IL-6 attenuated the association between rheumatoid arthritis and coronary calcification, suggesting its role as a potential mediator of enhanced atherosclerosis. Notably, increasing severity of rheumatoid arthritis was associated with a higher prevalence and extent of coronary calcification among both men and women with rheumatoid arthritis, and for all age categories. The largest percentage difference in coronary arterial calcification between rheumatoid arthritis patients and their nonrheumatoid arthritis counterparts was observed in the youngest age category.Conclusions
Increasing rheumatoid arthritis disease severity was associated with a higher prevalence and greater extent of coronary artery calcification, potentially mediated through an atherogenic effect of chronic systemic inflammation. Gender and age differences in association with coronary calcification suggest that preventive measures should be emphasized in men with rheumatoid arthritis, and considered even in younger rheumatoid arthritis patients with low levels of traditional cardiovascular risk factors. 相似文献97.
Background and purpose
Rapid increases in atmospheric carbon dioxide concentration ([CO2]) may increase crop residue production and carbon: nitrogen (C:N) ratio. Whether the incorporation of residues produced under elevated [CO2] will limit soil N availability and fertilizer N recovery in the plant is unknown. This study investigated the interaction between crop residue incorporation and elevated [CO2] on the growth, grain yield and the recovery of 15N-labeled fertilizer by wheat (Triticum aestivum L. cv. Yitpi) under controlled environmental conditions.Methods
Residue for ambient and elevated [CO2] treatments, obtained from wheat grown previously under ambient and elevated [CO2], respectively, was incorporated into two soils (from a cereal-legume rotation and a cereal-fallow rotation) 1 month before the sowing of wheat. At the early vegetative stage 15N-labeled granular urea (10.22 atom%) was applied at 50 kg?N ha?1 and the wheat grown to maturity.Results
When residue was not incorporated into the soil, elevated [CO2] increased wheat shoot (16 %) and root biomass (41 %), grain yield (19 %), total N uptake (4 %) and grain N removal (8 %). However, the positive [CO2] fertilization effect on these parameters was absent in the soil amended with residue. In the absence of residue, elevated [CO2] increased fertilizer N recovery in the plant (7 %), but when residue was incorporated elevated [CO2] decreased fertilizer N recovery.Conclusions
A higher fertilizer application rate will be required under future elevated [CO2] atmospheres to replenish the extra N removed in grains from cropping systems if no residue is incorporated, or to facilitate the [CO2] fertilization effect on grain yield by overcoming N immobilization resulting from residue amendment. 相似文献98.
Caroline Kijogi Daisuke Kimura Lam Quoc Bao Risa Nakamura Evans Asena Chadeka Ngetich Benard Cheruiyot Felix Bahati Kazuhide Yahata Osamu Kaneko Sammy M. Njenga Yoshio Ichinose Shinjiro Hamano Katsuyuki Yui 《Parasitology international》2018,67(3):284-293
Individuals living in malaria endemic areas become clinically immune after multiple re-infections over time and remain infected without apparent symptoms. However, it is unclear why a long period is required to gain clinical immunity to malaria, and how such immunity is maintained. Although malaria infection is reported to induce inhibition of immune responses, studies on asymptomatic individuals living in endemic regions of malaria are relatively scarce. We conducted a cross-sectional study of immune responses in asymptomatic school children aged 4–16 years living in an area where Plasmodium falciparum and Schistosoma mansoni infections are co-endemic in Kenya. Peripheral blood mononuclear cells were subjected to flow cytometric analysis and cultured to determine proliferative responses and cytokine production. The proportions of cellular subsets in children positive for P. falciparum infection at the level of microscopy were comparable to the negative children, except for a reduction in central memory-phenotype CD8+ T cells and natural killer cells. In functional studies, the production of cytokines by peripheral blood mononuclear cells in response to P. falciparum crude antigens exhibited strong heterogeneity among children. In addition, production of IL-2 in response to anti-CD3 and anti-CD28 monoclonal antibodies was significantly reduced in P. falciparum-positive children as compared to -negative children, suggesting a state of unresponsiveness. These data suggest that the quality of T cell immune responses is heterogeneous among asymptomatic children living in the endemic region of P. falciparum, and that the responses are generally suppressed by active infection with Plasmodium parasites. 相似文献
99.
Schluter C Lam KK Brumm J Wu BW Saunders M Stevens TH Bryan J Conibear E 《Molecular biology of the cell》2008,19(4):1282-1294
Endosomal transport is critical for cellular processes ranging from receptor down-regulation and retroviral budding to the immune response. A full understanding of endosome sorting requires a comprehensive picture of the multiprotein complexes that orchestrate vesicle formation and fusion. Here, we use unsupervised, large-scale phenotypic analysis and a novel computational approach for the global identification of endosomal transport factors. This technique effectively identifies components of known and novel protein assemblies. We report the characterization of a previously undescribed endosome sorting complex that contains two well-conserved proteins with four predicted membrane-spanning domains. Vps55p and Vps68p form a complex that acts with or downstream of ESCRT function to regulate endosomal trafficking. Loss of Vps68p disrupts recycling to the TGN as well as onward trafficking to the vacuole without preventing the formation of lumenal vesicles within the MVB. Our results suggest the Vps55/68 complex mediates a novel, conserved step in the endosomal maturation process. 相似文献
100.
Evidence that arginyl-glycyl-aspartate peptides and fibrinogen gamma chain peptides share a common binding site on platelets 总被引:15,自引:0,他引:15
S C Lam E F Plow M A Smith A Andrieux J J Ryckwaert G Marguerie M H Ginsberg 《The Journal of biological chemistry》1987,262(3):947-950
Synthetic peptides corresponding to the carboxyl terminus of the fibrinogen gamma chain inhibit the binding of fibrinogen, fibronectin, and von Willebrand factor to platelets, yet the active decapeptide sequence has only been found in fibrinogen to date. In contrast, all three proteins contain Arg-Gly-Asp sequences, and peptides containing Arg-Gly-Asp are potent inhibitors of their binding to activated platelets. We have analyzed the relationship between these peptide sets by direct binding assays. H12 (gamma 400-411) inhibited the binding of an Arg-Gly-Asp-containing peptide to platelets with similar dose response to inhibition of fibronectin binding. We have previously reported that GPIIb-IIIa binds to immobilized Arg-Gly-Asp peptides and can be eluted by Arg-Gly-Asp-containing peptides in solution. Both H12 and L10 (gamma 402-411) completely eluted GPIIb-IIIa bound to immobilized Arg-Gly-Asp peptides. Conversely, when GPIIb-IIIa was bound to immobilized L10, either L10 or an Arg-Gly-Asp peptide could elute it. Peptide specificity was established by the failure of Gly-Arg-Gly-Glu-Ser-Pro or acetylated L10 to elute GPIIb-IIIa from the immobilized peptides. These results indicate that the two peptide sets interact with the same receptor which contains GPIIb-IIIa. 相似文献