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排序方式: 共有234条查询结果,搜索用时 15 毫秒
41.
Sven Ruf Mahanandeesha Siddappa Hallur Nisha K. Anchan Indu N. Swamy Karthikai Raj Murugesan Sayantani Sarkar Lokesh Kananti Narasimhulu V.P. Rama Kishore Putta Shama Shaik Devaraj Venkatapura Chandrasekar Vishal Subhash Mane Sanjay Venkatachalapathi Kadnur Juluri Suresh Ravi Kanth Bhamidipati Manvi Singh Raghunadha Reddy Burri Rajendra Kristam Herman Schreuder Sridharan Rajagopal 《Bioorganic & medicinal chemistry letters》2018,28(5):922-925
Nicotinamide N-methyltransferase (NNMT) has been linked to obesity and diabetes. We have identified a novel nicotinamide (NA) analog, compound 12 that inhibited NNMT enzymatic activity and reduced the formation of 1-methyl-nicotinamide (MNA), the primary metabolite of NA by ~80% at 2?h when dosed in mice orally at 50?mg/kg. 相似文献
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S. K. Grover K. Sridharan K. K. Srivastava 《International journal of biometeorology》1987,31(2):163-168
The sequential changes in serum total protein concentration and in various electrophoretic fractions among lowlanders during two years of stay at high altitude (4,000 m) were determined and compared with that of high altitude natives (Ladakhis). The albumin to globulin ratio decreased during the early period of exposure to altitude among lowlanders and continued to remain at that level with minor fluctuations during the entire period of stay at altitude. Among the high altitude natives, a decreased albumin to globulin ratio with low serum protein concentration was observed. The composition of globulins separated electro-phoretically was of similar pattern in altitude natives and in lowlanders after a stay of two years at altitude. Among these subjects the-globulin was significantly higher as compared to values at sea level. 相似文献
44.
Fluorodensitometric evaluation of gentamicin from plasma and urine by high-performance thin-layer chromatography 总被引:1,自引:0,他引:1
Chhanda P Bhogte V.B Patravale Padma V Devarajan 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,694(2):1246
High-performance thin-layer chromatographic (HPTLC) analysis of gentamicin by in situ fluorodensitometric evaluation of its 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) derivative is presented. The aminoglycoside components separated on silica gel plates using chloroform–methanol–20% ammonium hydroxide (2.4:2.2:1.5, v/v/v) as the mobile phase were reacted with NB-Cl to yield highly fluorescent derivatives. The calibration curves of gentamicin in water, plasma and urine were linear in the range 40–200 ng. The mean values of intercept, slope and correlation coefficient were 16.82±0.473, 6.83±0.015 and 0.9968±0.0017 for standard curves in water, 17.35±0.375, 6.85±0.018 and 0.9941±0.0012 for standard curves in plasma and 14.35±0.286, 6.86±0.002 and 0.9933+0.0011 for standard curves in urine respectively. The analytical technique was validated for within-day and day-to-day variation. The results indicate that HPTLC, coupled with in situ fluorodensitometry, is a reliable and valuable technique for quantitative analysis of the bulk drug gentamicin and gentamicin from urine and plasma. 相似文献
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The present study evaluates freeze thaw as a simple approach for screening the most appropriate cryoprotectant. Freeze–thaw
study is based on the principle that an excipient, which protects nanoparticles during the first step of freezing, is likely
to be an effective cryoprotectant. Nanoparticles of rifampicin with high entrapment efficiency were prepared by the emulsion-solvent
diffusion method using dioctyl sodium sulfosuccinate (AOT) as complexing agent and Gantrez AN-119 as polymer. Freeze–thaw
study was carried out using trehalose and fructose as cryoprotectants. The concentration of cryoprotectant, concentration
of nanoparticles in the dispersion, and the freezing temperature were varied during the freeze–thaw study. Cryoprotection
increased with increase in cryoprotectant concentration. Further, trehalose was superior to fructose at equivalent concentrations
and moreover permitted use of more concentrated nanosuspensions for freeze drying. Freezing temperature did not influence
the freeze–thaw study. Freeze-dried nanoparticles revealed good redispersibility with a size increase that correlated well
with the freeze–thaw study at 20% w/v trehalose and fructose. Transmission electron microscopy revealed round particles with a size ∼400 nm, which correlated with
photon correlation spectroscopic measurements. Differential scanning calorimetry and X-ray diffraction suggested amorphization
of rifampicin. Fourier transfer infrared spectroscopy could not confirm interaction of drug with AOT. Nanoparticles exhibited
sustained release of rifampicin, which followed diffusion kinetics. Nanoparticles of rifampicin were found to be stable for
12 months. The good correlation between freeze thaw and freeze drying suggests freeze–thaw study as a simple and quick approach
for screening optimal cryoprotectant for freeze drying. 相似文献
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Sudharsan Sridharan Nigel Howard Micha? B?aszczyk Tom L. Blundell 《Journal of molecular biology》2010,397(1):290-7483
EntC, one of two isochorismate synthases in Escherichia coli, is specific to the biosynthesis of the siderophore enterobactin. Here, we report the crystal structure of EntC in complex with isochorismate and Mg2+at 2.3 Å resolution, the first structure of a chorismate-utilizing enzyme with a non-aromatic reaction product. EntC exhibits a complex α+β fold like the other chorismate-utilizing enzymes, such as salicylate synthase and anthranilate synthase. Comparison of active site structures allowed the identification of several residues, not discussed previously, that might be important for the isochorismate activity of the EntC. Although EntC, MenF and Irp9 all convert chorismate to isochorismate, only Irp9 subsequently exhibits isochorismate pyruvate lyase activity resulting in the formation of salicylate and pyruvate as the reaction products. With a view to understanding the roles of these amino acid residues in the conversion of chorismate to isochorismate and to obtaining clues about the pyruvate lyase activity of Irp9, several mutants of EntC were generated in which the selected residues in EntC were substituted for those of Irp9: these included A303T, L304A, F327Y, I346L and F359Q mutations. Biochemical analysis of these mutants indicated that the side chain of A303 in EntC may be crucial in the orientation of the carbonyl to allow formation of a hydrogen bond with isochorismate. Some mutations, such as L304A and F359Q, give rise to a loss of catalytic activity, whereas others, such as F327Y and I346L, show that subtle changes in the otherwise closely similar active sites influence activity. We did not find a combination of these residues that conferred pyruvate lyase activity. 相似文献
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