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排序方式: 共有266条查询结果,搜索用时 15 毫秒
1.
2.
Dipicolinic acid synthesis inPenicillium citreoviride strain 3114 was inhibited by Ca2+ ions, but not by Ba2+, Cu2+or Fe2+. Among the metals tested, only Zn2+ inhibited the synthesis of dipicolinic acid and promoted sporulation. None of these metals reversed the inhibition by Ca2+ or Zn2+. A mutant 27133-dpa-ca selected for resistance to feedback inhibition by dipicolinic acid: Ca2+ complex showed cross-resistance to inhibition by dipicolinic acid: Zn2+. Both 3114 and271 33-dpa-ca excreted a number of aliphatic and amino acids during secondary metabolism of dipicolinic acid. In the presence of 1000 ppm
of Ca2+, accumulation of citric acid and α-aminoadipic acid was completely inhibited under conditions of inhibition of dipicolinic
acid in parent strain 3114 but not in the mutant. Citric acid with or without Ca2+ did not inhibit thede novo synthesis of dipicolinic acid in the strain 3114. In fact, citric acid in the presence of Ca2+ improved significantly rate of dipicolinic acid synthesis. Apart from resistance to feed back inhibition by dipicolinic acid:
Ca2+ complex, mutant differed from the parent in three other aspectsviz. (i) dipicolinic acid synthesis was not subject to catabolite repression by glucose, (ii) sporulation as well as dipicolinic
acid synthesis was dependent on the presence of Ca2+ ions in the medium and (iii) Mg2+ requirement for the mutant increased three fold. Higher requirement of the Mg2+ could be partially relieved by Ca2+ during secondary metabolism. The results support the inference thatde novo synthesis of dipicolinic acid is regulated through feedback inhibition by dipicolinic acid: Ca2+complex. 相似文献
3.
Summary Enhancing Factor (EF) is a 14 kDa protein isolated from mouse small intestines, which enhances the binding of 125I-EGF to A431 cells. This observation as well as our earlier in vitro studies have indicated that EF is a modulator of EGF. In adult mice, localization of EF by immunohistochemistry shows it is present pre-dominantly in the Paneth cells of the small intestines and to a lesser extent in the stomach and colon. This study of the ontogeny of EF shows that the appearance of the protein coincides with the appearance of mature Paneth cells. In new born mouse skin EF is localized in the hair follicles in the first hair cycle from day 2 to day 8. It is however absent in the adult skin. Thus EF is associated with tissues which have a high growth rate. 相似文献
4.
Clostridium pasteurianum total cellular saturated fatty acids increased through its growth cycle from 81% to 91% but varied significantly in the composition
under nitrogen- and non-nitrogen-fixing conditions. During ammonia-assimilating growth, palmitic acid decreased from 67.7%
to 43.5% by late log while marked increases in shorter chain saturated fatty acids (C15:0 and below) and a long chain saturated C22:0 occured. In contrast, under N2-fixing growth conditions, palmitic acid increased from 45.5% to 84.3% by late log, representing nearly the total amound of
saturated fatty acids found inC. pasteurianum. The total cellular lipid concentration decreased as the culture aged. irrespective of the nitrogen sources; however, the
phospholipid concentration increased significantly during N2-fixing growth as compared with a 50% decrease during ammonia-assimilating conditions. The implication of these differences
and possible role of palmitic acid and phospholipids inC. pasteurianum nitrogen fixation process are discussed. 相似文献
5.
Edis Dzananovic Trushar R. Patel Soumya Deo Kevin McEleney J?rg Stetefeld Sean A. McKenna 《RNA (New York, N.Y.)》2013,19(3):333-344
In humans, the double-stranded RNA (dsRNA)-activated protein kinase (PKR) is expressed in late stages of the innate immune response to viral infection by the interferon pathway. PKR consists of tandem dsRNA binding motifs (dsRBMs) connected via a flexible linker to a Ser/Thr kinase domain. Upon interaction with viral dsRNA, PKR is converted into a catalytically active enzyme capable of phosphorylating a number of target proteins that often results in host cell translational repression. A number of high-resolution structural studies involving individual dsRBMs from proteins other than PKR have highlighted the key features required for interaction with perfectly duplexed RNA substrates. However, viral dsRNA molecules are highly structured and often contain deviations from perfect A-form RNA helices. By use of small-angle X-ray scattering (SAXS), we present solution conformations of the tandem dsRBMs of PKR in complex with two imperfectly base-paired viral dsRNA stem–loops; HIV-1 TAR and adenovirus VAI-AS. Both individual components and complexes were purified by size exclusion chromatography and characterized by dynamic light scattering at multiple concentrations to ensure monodispersity. SAXS ab initio solution conformations of the individual components and RNA–protein complexes were determined and highlight the potential of PKR to interact with both stem and loop regions of the RNA. Excellent agreement between experimental and model-based hydrodynamic parameter determination heightens our confidence in the obtained models. Taken together, these data support and provide a framework for the existing biochemical data regarding the tolerance of imperfectly base-paired viral dsRNA by PKR. 相似文献
6.
Melissa Latigo Mugambi Sarang Deo Adeodata Kekitiinwa Charles Kiyaga Mendel E. Singer 《PloS one》2013,8(11)
Background
There is scant evidence on the association between diagnosis delays and the receipt of test results in HIV Early Infant Diagnosis (EID) programs. We determine the association between diagnosis delays and other health care system and patient factors on result receipt.Methods
We reviewed 703 infant HIV test records for tests performed between January 2008 and February 2009 at a regional referral hospital and level four health center in Uganda. The main outcome was caregiver receipt of the test result. The primary study variable was turnaround time (time between sample collection and result availability at the health facility). Additional variables included clinic entry point, infant age at sample collection, reported HIV status and receipt of antiretroviral prophylaxis for prevention of mother-to-child transmission. We conducted a pooled analysis in addition to separate analyses for each facility. We estimated the relative risk of result receipt using modified Poisson regression with robust standard errors.Results
Overall, the median result turnaround time, was 38 days. 59% of caregivers received infant test results. Caregivers were less likely to receive results at turnaround times greater than 49 days compared to 28 days or fewer (ARR = 0.83; 95% CI = 0.70–0.98). Caregivers were more likely to receive results at the PMTCT clinic (ARR = 1.81; 95% CI = 1.40–2.33) and less likely at the pediatric ward (ARR = 0.54; 95% CI = 0.37–0.81) compared to the immunization clinic. At the level four health center, result receipt was half as likely among infants older than 9 months compared to 3 months and younger (ARR= 0.47; 95% CI = 0.25–0.93).Conclusion
In this study setting, we find evidence that longer turnaround times, clinic entry point and age at sample collection may be associated with receipt of infant HIV test results. 相似文献7.
Aadithya Arumugam Zhiping Weng Sarang S. Talwelkar Sandeep C. Chaudhary Levy Kopelovich Craig A. Elmets Farrukh Afaq Mohammad Athar 《PloS one》2013,8(11)
Non-melanoma skin cancer (NMSC) is the most common type of skin cancer in Caucasian populations. Its increasing incidence has been a major public health concern. Elevated expressions of ODC and COX-2 are associated with both murine and human NMSCs. Inhibition of these molecular targets singly employing their respective small molecule inhibitors showed limited success. Here, we show that combined blockade of ODC and COX-2 using their potent inhibitors, DFMO and diclofenac respectively abrogates growth of A431 epidermal xenograft tumors in nu/nu mice by more than 90%. The tumor growth inhibition was associated with a diminution in the proliferation and enhancement in apoptosis. The proliferation markers such as PCNA and cyclin D1 were reduced. TUNEL-positive apoptotic cells and cleaved caspase-3 were increased in the residual tumors. These agents also manifested direct target-unrelated effects. Reduced expression of phosphorylated MAPKAP-2, ERK, and Akt (ser473 & thr308) were noticed. The mechanism by which combined inhibition of ODC/COX attenuated tumor growth and invasion involved reduction in EMT. Akt activation by ODC+COX-2 over-expression was the key player in this regard as Akt inhibition manifested effects similar to those observed by the combined inhibition of ODC+COX-2 whereas forced over-expression of Akt resisted against DFMO+diclofenac treatment. These data suggest that ODC+COX-2 over-expression together leads to pathogenesis of aggressive and invasive cutaneous carcinomas by activating Akt signaling pathway, which through augmenting EMT contributes to tumor invasion. 相似文献
8.
Manju Shri Arti Rai Pankaj Kumar Verma Prashant Misra Sonali Dubey Smita Kumar Sikha Verma Neelam Gautam Rudra Deo Tripathi Prabodh Kumar Trivedi Debasis Chakrabarty 《Protoplasma》2013,250(2):631-636
Agrobacterium-mediated transformation of indica rice varieties has been quite difficult as these are recalcitrant to in vitro responses. In the present study, we established a high-efficiency Agrobacterium tumefaciens-mediated transformation system of rice (Oryza sativa L. ssp. indica) cv. IR-64, Lalat, and IET-4786. Agrobacterium strain EHA-101 harboring binary vector pIG121-Hm, containing a gene encoding for β-glucuronidase (GUS) and hygromycin resistance, was used in the transformation experiments. Manipulation of different concentrations of acetosyringone, days of co-culture period, bacterial suspension of different optical densities (ODs), and the concentrations of l-cysteine in liquid followed by solid co-culture medium was done for establishing the protocol. Among the different co-culture periods, 5 days of co-culture with bacterial cells (OD600 nm?=?0.5–0.8) promoted the highest frequency of transformation (83.04 %) in medium containing l-cysteine (400 mg l?1). Putative transformed plants were analyzed for the presence of a transgene through genomic PCR and GUS histochemical analyses. Our results also suggest that different cultural conditions and the addition of l-cysteine in the co-culture medium improve the Agrobacterium-mediated transformation frequencies from an average of 12.82 % to 33.33 % in different indica rice cultivars. 相似文献
9.
Gabriele Pohlig Sonja C. Bernhard Johannes Blum Christian Burri Alain Mpanya Jean-Pierre Fina Lubaki Alfred Mpoo Mpoto Blaise Fungula Munungu Patrick Mangoni N’tombe Gratias Kambau Manesa Deo Pierre Nsele Mutantu Florent Mbo Kuikumbi Alain Fukinsia Mintwo Augustin Kayeye Munungi Amadeu Dala Stephen Macharia Constantin Miaka Mia Bilenge Victor Kande Betu Ku Mesu Jose Ramon Franco Ndinga Dieyi Dituvanga Richard R. Tidwell Carol A. Olson 《PLoS neglected tropical diseases》2016,10(2)
Background
Sleeping sickness (human African trypanosomiasis [HAT]) is a neglected tropical disease with limited treatment options that currently require parenteral administration. In previous studies, orally administered pafuramidine was well tolerated in healthy patients (for up to 21 days) and stage 1 HAT patients (for up to 10 days), and demonstrated efficacy comparable to pentamidine.Methods
This was a Phase 3, multi-center, randomized, open-label, parallel-group, active control study where 273 male and female patients with first stage Trypanosoma brucei gambiense HAT were treated at six sites: one trypanosomiasis reference center in Angola, one hospital in South Sudan, and four hospitals in the Democratic Republic of the Congo between August 2005 and September 2009 to support the registration of pafuramidine for treatment of first stage HAT in collaboration with the United States Food and Drug Administration. Patients were treated with either 100 mg of pafuramidine orally twice a day for 10 days or 4 mg/kg pentamidine intramuscularly once daily for 7 days to assess the efficacy and safety of pafuramidine versus pentamidine. Pregnant and lactating women as well as adolescents were included.The primary efficacy endpoint was the combined rate of clinical and parasitological cure at 12 months. The primary safety outcome was the frequency and severity of adverse events. The study was registered on the International Clinical Trials Registry Platform at www.clinicaltrials.gov with the number ISRCTN85534673.Findings/Conclusions
The overall cure rate at 12 months was 89% in the pafuramidine group and 95% in the pentamidine group; pafuramidine was non-inferior to pentamidine as the upper bound of the 95% confidence interval did not exceed 15%. The safety profile of pafuramidine was superior to pentamidine; however, 3 patients in the pafuramidine group had glomerulonephritis or nephropathy approximately 8 weeks post-treatment. Two of these events were judged as possibly related to pafuramidine. Despite good tolerability observed in preceding studies, the development program for pafuramidine was discontinued due to delayed post-treatment toxicity. 相似文献10.
Deo RC Patterson N Tandon A McDonald GJ Haiman CA Ardlie K Henderson BE Henderson SO Reich D 《PLoS genetics》2007,3(11):e196
Hypertension (HTN) is a devastating disease with a higher incidence in African Americans than European Americans, inspiring searches for genetic variants that contribute to this difference. We report the results of a large-scale admixture scan for genes contributing HTN risk, in which we screened 1,670 African Americans with HTN and 387 control individuals for regions of the genome with elevated proportion of African or European ancestry. No loci were identified that were significantly associated with HTN. We also searched for evidence of an admixture signal at 40 candidate genes and eight previously reported linkage peaks, but none appears to contribute substantially to the differential HTN risk between African and European Americans. Finally, we observed nominal association at one of the loci detected in the admixture scan of Zhu et al. 2005 (p = 0.016 at 6q24.3 correcting for four hypotheses tested), although we caution that the significance is marginal and the estimated odds ratio of 1.19 per African allele is less than what would be expected from the original report; thus, further work is needed to follow up this locus. 相似文献