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排序方式: 共有249条查询结果,搜索用时 15 毫秒
21.
Bulbul Ahmed Bin Cao Jeffrey S. McLean Tuba Ica Alice Dohnalkova Ozlem Istanbullu Akin Paksoy Jim K. Fredrickson Haluk Beyenal 《Applied and environmental microbiology》2012,78(22):8001-8009
A facultative iron-reducing [Fe(III)-reducing] Paenibacillus sp. strain was isolated from Hanford 300A subsurface sediment biofilms that was capable of reducing soluble Fe(III) complexes [Fe(III)-nitrilotriacetic acid and Fe(III)-citrate] but unable to reduce poorly crystalline ferrihydrite (Fh). However, Paenibacillus sp. 300A was capable of reducing Fh in the presence of low concentrations (2 μM) of either of the electron transfer mediators (ETMs) flavin mononucleotide (FMN) or anthraquinone-2,6-disulfonate (AQDS). Maximum initial Fh reduction rates were observed at catalytic concentrations (<10 μM) of either FMN or AQDS. Higher FMN concentrations inhibited Fh reduction, while increased AQDS concentrations did not. We also found that Paenibacillus sp. 300A could reduce Fh in the presence of natural ETMs from Hanford 300A subsurface sediments. In the absence of ETMs, Paenibacillus sp. 300A was capable of immobilizing U(VI) through both reduction and adsorption. The relative contributions of adsorption and microbial reduction to U(VI) removal from the aqueous phase were ∼7:3 in PIPES [piperazine-N,N′-bis(2-ethanesulfonic acid)] and ∼1:4 in bicarbonate buffer. Our study demonstrated that Paenibacillus sp. 300A catalyzes Fe(III) reduction and U(VI) immobilization and that these reactions benefit from externally added or naturally existing ETMs in 300A subsurface sediments. 相似文献
22.
Cronin M Akin AR Collins SA Meganck J Kim JB Baban CK Joyce SA van Dam GM Zhang N van Sinderen D O'Sullivan GC Kasahara N Gahan CG Francis KP Tangney M 《PloS one》2012,7(1):e30940
The ability to track microbes in real time in vivo is of enormous value for preclinical investigations in infectious disease or gene therapy research. Bacteria present an attractive class of vector for cancer therapy, possessing a natural ability to grow preferentially within tumours following systemic administration. Bioluminescent Imaging (BLI) represents a powerful tool for use with bacteria engineered to express reporter genes such as lux. BLI is traditionally used as a 2D modality resulting in images that are limited in their ability to anatomically locate cell populations. Use of 3D diffuse optical tomography can localize the signals but still need to be combined with an anatomical imaging modality like micro-Computed Tomography (μCT) for interpretation.In this study, the non-pathogenic commensal bacteria E. coli K-12 MG1655 and Bifidobacterium breve UCC2003, or Salmonella Typhimurium SL7207 each expressing the luxABCDE operon were intravenously (i.v.) administered to mice bearing subcutaneous (s.c) FLuc-expressing xenograft tumours. Bacterial lux signal was detected specifically in tumours of mice post i.v.-administration and bioluminescence correlated with the numbers of bacteria recovered from tissue. Through whole body imaging for both lux and FLuc, bacteria and tumour cells were co-localised. 3D BLI and μCT image analysis revealed a pattern of multiple clusters of bacteria within tumours. Investigation of spatial resolution of 3D optical imaging was supported by ex vivo histological analyses. In vivo imaging of orally-administered commensal bacteria in the gastrointestinal tract (GIT) was also achieved using 3D BLI. This study demonstrates for the first time the potential to simultaneously image multiple BLI reporter genes three dimensionally in vivo using approaches that provide unique information on spatial locations. 相似文献
23.
M Serdar E Sertoglu M Uyanik S Tapan K Akin C Bilgi I Kurt 《Free radical research》2012,46(10):1291-1295
Abstract Background. Measurement of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) has recently become more popular as a means of assessing oxidative stress in the human body. The aim of this study is to compare the levels of urine 8-OHdG in patients with type 2 diabetes with and without nephropathy and to evaluate its role as a biochemical marker for distinguishing these patients from healthy and patients without complications. Methods. For this purpose, 52 patients with type 2 diabetes mellitus (32 with nephropathy (DMN), 20 without nephropathy (DM)) and 20 healthy control subjects (C) were included in this study. The urine concentrations of 8-OHdG were measured by modified LC-MS/MS method and compared with the first morning voiding urine albumin/creatinine ratio (UACR) and HbA1c values of the same patients. Results. The concentrations of urine 8-OHdG in DMN and DM patients were higher than those of the control subjects (3.47?±?0.94, 2.92?±?1.73, 2.1?±?0.93 nmol/mol creatinine, respectively). But there was no statistical difference between DMN and DM (p =?0.115). There is significant correlation between urinary 8-OHdG and UACR (r =?0.501, p 0.001). According to ROC analysis, the AUC value of HbA1c was higher than the value of the AUC of 8-OHdG (0.882 and 0.771, respectively). Conclusions. This study shows that the urine 8-OHdG levels increase in diabetic patients. However, urinary 8-OHdG is not a useful clinical marker, compared with UACR, to predict the development of diabetic nephropathy in diabetic patients. 相似文献
24.
Ogura Y Naito H Akin S Ichinoseki-Sekine N Kurosaka M Kakigi R Sugiura T Powers SK Katamoto S Demirel HA 《American journal of physiology. Regulatory, integrative and comparative physiology》2008,294(5):R1600-R1607
This study examined whether the exercise-increased extracellular heat shock protein 72 (eHsp72) levels in rats was associated with body temperature elevation during exercise. In all, 26 female Sprague-Dawley rats (3 mo old) were assigned randomly to control (CON; n = 8), exercise under warm temperature (WEx; n = 9), or exercise under cold temperature (CEx; n = 9). The WEx and CEx were trained at 25 degrees C or 4 degrees C, respectively, for nine days using a treadmill. Before and immediately after the final exercise bout, the colonic temperatures were measured as an index of body temperature. The animals were subsequently anesthetized, and blood samples were collected and centrifuged. Plasma samples were obtained to assess their eHsp72 levels. Only the colonic temperature in WEx was increased significantly (P < 0.05) by exercise. The eHsp72 level in WEx was significantly higher (P < 0.05) than that of either the CON or CEx. However, no significant difference was found between CON and CEx. Regression analyses revealed that the eHsp72 level increased as a function of the body temperature. In another experiment, the eHsp72 level of animals with body temperature that was passively elevated through similar kinetics to those of the exercise was studied. Results of this experiment showed that mere body temperature elevation was insufficient to induce eHsp72 responses. Collectively, our results suggest that body temperature elevation during exercise is important for induction of exercise-increased eHsp72. In addition, the possible role of body temperature elevation is displayed when the exercise stressor is combined with it. 相似文献
25.
Effect of Strontium Ranelate on Hydrogen Peroxide-Induced Apoptosis of CRL-11372 Cells 总被引:2,自引:0,他引:2
Senkoylu A Yilmaz A Ergun MA Ilhan MN Simsek A Altun N Bolukbasi S Menevse S 《Biochemical genetics》2008,46(3-4):197-205
In vitro and in vivo studies have proven strontium to be an osteoinductive trace element. The effect of strontium ranelate
(SR) on H2O2-induced apoptosis of CRL-11372 cells and optimization of its anti-apoptotic dose were the aims of this study. After 1 h of
pretreatment with SR 1 μM, 50 μM, 100 μM, 500 μM, and 1,000 μM concentrations, CRL-11372 osteoblasts were exposed to 100 μM H2O2 for periods of 6–12 h. The same experiments were repeated without H2O2. The apoptotic index and viability of cells were assessed quantitatively with a fluorescent dye and qualitatively with agarose
gel electrophoresis. Concentrations of 1–100 μM of SR with a 6-h treatment and only 1 μM concentration with a 12-h treatment
inhibited the apoptotic effect of H2O2 on cultured osteoblasts significantly (P < 0.05). SR was shown to inhibit H2O2-induced apoptosis of CRL-11372 cells in a dose-dependent manner. 相似文献
26.
Fiber degradation in Bermuda grass and orchard grass was evaluated gravimetrically and by scanning and transmission electron microscopy after incubation with pure cultures of rumen bacteria. Lachnospira multiparus D-32 was unable to degrade plant cell wall components. Butyrivibrio fibrisolvens 49 degraded 6 and 14.9% of the fiber components in Bermuda grass and orchard grass, respectively, and Ruminococcus albus 7 degraded 11.4% orchard grass fiber but none in Bermuda grass. Both B. fibrisolvens and R. albus lacked capsules, did not adhere to fiber, and degraded only portions of the more easily available plant cell walls. R. flavefaciens FD-1 was the most active fiber digester, degrading 8.2 and 55.3% of Bermuda and orchard grass fiber, respectively. The microbe had a distinct capsule and adhered to fiber, especially that which is slowly degraded, but was able to cause erosion and disorganization of the more easily digested cell walls, apparently by extracellular enzymes. Results indicated that more digestible cell walls could be partially degraded by enzymes disassociated from cellulolytic and noncellulolytic bacteria, and data were consistent with the hypothesis that the more slowly degraded plant walls required attachment. Microbial species as well as the cell wall architecture influenced the physical association with and digestion of plant fiber. 相似文献
27.
trans-p-Coumaric acid inhibited the growth of Bacteroides ruminicola on both cellobiose and glucose, while trans-ferulic acid and vanillin retarded growth. The phenolic monomers varied in their potential to inhibit the Bacteroides succinogenes beta-glucosidase, carboxymethylcellulase, and xylanase, with p-coumaric acid being the most inhibitory. The B. ruminicola beta-glucosidase was inhibited less than 10% by all three compounds. 相似文献
28.
Domination among strategies in an evolutionary game implies that the geometric mean of the frequencies of certain strategies—the unfit—approaches zero. However, as we show by example no one strategy need be eliminated in the limit. 相似文献
29.
30.
Processing of a newly identified intermediate of human myeloperoxidase in isolated granules occurs at neutral pH 总被引:1,自引:0,他引:1
Myeloperoxidase is a major component of specialized lysosomes known as azurophil granules in polymorphonuclear leukocytes or neutrophils. The processing of myeloperoxidase in human HL-60 promyelocytic leukemia cells was studied by pulse-labeling cells in culture with [35S]methionine followed by immunoprecipitation and identification of myeloperoxidase polypeptides from cell fractions after various chase intervals. These studies revealed the presence of a previously unidentified intermediate with Mr 74,000 which kinetically followed the appearance of a larger Mr 81,000 intermediate. Using an in vitro lysosomal preparation the newly identified Mr 74,000 intermediate was directly converted within protected granules to mature forms of myeloperoxidase (Mr 63,000 and 60,000). This conversion occurred optimally at pH 7.5 and was not inhibited by lysosomotropic agents (chloroquine, NH4Cl) or protonophores (monensin, carbonyl cyanide p-trifluoromethoxyphenylhydrazone). Furthermore, the uptake of radiolabeled amines indicated a neutral intragranular environment (pH 7.35-7.67) which remained unchanged in the presence and absence of 1 mM ATP or 2.5 microM carbonyl cyanide p-trifluoromethoxyphenylhydrazone. We conclude that, in contrast to other lysosomal pathways, the final proteolytic cleavage of myeloperoxidase does not require an acidic environment. 相似文献