6 research outputs found
A Novel Thermostable Cytochrome P450 from Sequence-Based Metagenomics of Binh Chau Hot Spring as a Promising Catalyst for Testosterone Conversion
Biotechnological applications of cytochromes P450 show difficulties, such as low activity,
thermal and/or solvent instability, narrow substrate specificity and redox partner dependence. In an
attempt to overcome these limitations, an exploitation of novel thermophilic P450 enzymes from
nature via uncultured approaches is desirable due to their great advantages that can resolve nearly
all mentioned impediments. From the metagenomics library of the Binh Chau hot spring, an open
reading frame (ORF) encoding a thermostable cytochrome P450—designated as P450-T3—which
shared 66.6% amino acid sequence identity with CYP109C2 of Sorangium cellulosum So ce56 was
selected for further identification and characterization. The ORF was synthesized artificially and
heterologously expressed in Escherichia coli C43(DE3) using the pET17b system. The purified enzyme
had a molecular weight of approximately 43 kDa. The melting temperature of the purified enzyme
was 76.2 ◦C and its apparent half-life at 60 ◦C was 38.7 min. Redox partner screening revealed that
P450-T3 was reduced well by the mammalian AdR-Adx4-108 and the yeast Arh1-Etp1 redox partners.
Lauric acid, palmitic acid, embelin, retinoic acid (all-trans) and retinoic acid (13-cis) demonstrated
binding to P450-T3. Interestingly, P450-T3 also bound and converted testosterone. Overall, P450-T3
might become a good candidate for biocatalytic applications on a larger scale
Những xu hướng ứng dụng công nghệ thông tin trong dạy học ngoại ngữ ở Việt Nam
Mục đích của bài báo là trình bày tổng quan về các khuynh hướng ứng dụng công nghệ thông tin trong dạy và học ngoại ngữ tại Việt Nam. Trên cơ sở tập hơp kết quả từ các nghiên cứu ứng dụng trong bối cảnh Việt Nam, bài báo mô tả ba xu hướng ứng dụng, bao gồm dạy và học dựa vào máy tính, dạy và học dựa vào trang mạng và dạy và học trực tuyến. Bài báo cũng đề cập đến hai nhận định về các xu hướng ứng dụng có liên quan đến hai đặc trưng cơ bản của ba xu hướng trên đây, bao gồm tính cập nhật của các ứng dụng và quy mô của xu hướng
Bacterial risk factors for treatment failure and relapse among patients with isoniazid resistant tuberculosis
Background
Drug resistant tuberculosis (TB) is increasing in prevalence worldwide. Treatment failure and relapse is known to be high for patients with isoniazid resistant TB treated with standard first line regimens. However, risk factors for unfavourable outcomes and the optimal treatment regimen for isoniazid resistant TB are unknown. This cohort study was conducted when Vietnam used the eight month first line treatment regimen and examined risk factors for failure/relapse among patients with isoniazid resistant TB.
Methods
Between December 2008 and June 2011 2090 consecutive HIV-negative adults (≥18 years of age) with new smear positive pulmonary TB presenting at participating district TB units in Ho Chi Minh City were recruited. Participants with isoniazid resistant TB identified by Microscopic Observation Drug Susceptibility (MODS) had extended follow-up for 2 years with mycobacterial culture to test for relapse. MGIT drug susceptibility testing confirmed 239 participants with isoniazid resistant, rifampicin susceptible TB. Bacterial and demographic factors were analysed for association with treatment failure and relapse.
Results
Using only routine programmatic sputum smear microscopy for assessment, (months 2, 5 and 8) 30/239 (12.6%) had an unfavourable outcome by WHO criteria. Thirty-nine patients were additionally detected with unfavourable outcomes during 2 year follow up, giving a total of 69/239 (28.9%) of isoniazid (INH) resistant cases with unfavourable outcome by 2 years of follow-up. Beijing lineage was the only factor significantly associated with unfavourable outcome among INH-resistant TB cases during 2 years of follow-up. (adjusted OR = 3.16 [1.54–6.47], P = 0.002).
Conclusion
One third of isoniazid resistant TB cases suffered failure/relapse within 2 years under the old eight month regimen. Over half of these cases were not identified by standard WHO recommended treatment monitoring. Intensified research on early identification and optimal regimens for isoniazid resistant TB is needed. Infection with Beijing genotype of TB is a significant risk factor for bacterial persistence on treatment resulting in failure/relapse within 2 years. The underlying mechanism of increased tolerance for standard drug regimens in Beijing genotype strains remains unknown