Interaction of a fluorescent analog of N -deacetyl-N -methyl-colchicine (colcemid) with liver alcohol dehydrogenase

The evidence for specific binding of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-colcemid (NBD-colcemid), a fluorescent analog of colcemid (N-deacetyl-N-methyl-colchicine), to liver alcohol dehydrogenase is presented. Alcohol dehydrogenase bound NBD-colcemid in a time-dependent manner, enhanced the fluorescence intensity, and caused a large blue shift of the emission maximum of the free drug. The specificity of binding was determined for both the colchicine nucleus and the NBD moiety. The binding was not affected by the presence of alcohol or NAD in the reaction mixture. Preincubation of horse liver alcohol dehydrogenase with colcemid inhibited the binding to a considerable extent. NBD-colcemid inhibited the enzymic activity of alcohol dehydrogenase in a mixed-type noncompetitive mode with a Ki value of 32 μM, whereas colcemid showed noncompetitive inhibition with a Ki of 100 μM. The association rate constant of NBD-colcemid binding with liver alcohol dehydrogenase was 587 M-1 s-1 at 25 °C. The stoichiometry and dissociation constant of the binding reaction were 0.62/dimer and 12 μM, respectively. Donor quenching experiments showed that both tryptophans of alcohol dehydrogenase transferred energy to the bound NBD-colcemid. Thus, this study reports the binding of a colchicine analog to a protein other than tubulin with high affinity. It is concluded that NBD-colcemid binding to dehydrogenases is a general phenomenon, but the common structural element(s) that is responsible for the binding activity, and which exists among tubulin and dehydrogenases, has yet to be determined

Drug Trafficking Routes and Hepatitis B in Injection Drug Users, Manipur, India

Prevalence of hepatitis B genotype C in injection drug users in the northeastern Indian state of Manipur, neighboring the "Golden Triangle," correlates well with overland drug-trafficking routes, the injection drug use epidemic, and the spread of HIV. Further spread to other regions of India through mobile populations is possible

Anti-hepatitis B core antigen testing with detection and characterization of occult hepatitis B virus by an in-house nucleic acid testing among blood donors in Behrampur, Ganjam, Orissa in southeastern India: implications for transfusion

<p>Abstract</p> <p>Background</p> <p>Occult hepatitis B virus (HBV) infection might transmit viremic units into the public blood supply if only hepatitis B surface antigen (HBsAg) testing is used for donor screening. Our aim was to evaluate the prevalence of occult HBV infection among the HBsAg negative/antiHBc positive donations from a highly HIV prevalent region of India.</p> <p>Methods</p> <p>A total of 729 HBsAg negative donor units were included in this study. Surface gene and precore region were amplified by in house nucleic acid test (NAT) for detection of occult HBV infection and surface gene was analyzed after direct sequencing.</p> <p>Results</p> <p>A total of 220 (30.1%) HBsAg negative donors were antiHBc positive, of them 66 (30%) were HBV DNA positive by NAT. HBV DNA positivity among 164 antiHBc only group, was 27.1% and among 40 antiHBs positive group was 30.0%. HBV/D (93.3%) was predominant and prevalence of both HBV/C and HBV/A was 3.3%. Single or multiple amino acids substitutions were found in 95% samples.</p> <p>Conclusion</p> <p>Thus, a considerable number of HBV infected donors remain undiagnosed, if only HBsAg is used for screening. Addition of antiHBc testing for donor screening, although will lead to rejection of a large number of donor units, will definitely eliminate HBV infected donations and help in reducing HBV transmission with its potential consequences, especially among the immunocompromised population. The HBV genetic diversity found in this donor population are in accordance with other parts of India.</p

Alumina and silica sols as binders in a typical ULC castable

Alumina and silica sols prepared from cheap pre_cursors have been characterized with respect to viscosity, zeta potential and differential thermal analysis. It has been observed that silica sol possesses higher viscosity and zeta potential values than those of alumina sol. The effect of these sols on high alumina based ULC castables has been investigated by comparing their bulk density, apparent porosity, cold crushing strength, flexural strength, slag corrosion and thermal shock resistance properties. XRD and SEM studies have been carried out on fired samples to explain the effect of sols on the fired strength and homogeneity in structure

Cardiovascular risk reduction intervention among school-students in Kolkata, West Bengal – The CRRIS study protocol

Background: Increasing burden of cardiovascular risk-factors among adolescent school-children is a major concern in India. Dearth of information regarding the burden of these factors and the efficacy of educational intervention in minimizing them among urban school-students of India called for a school-based, educational intervention involving a representative sample of these students and their caregivers. Methodology: Using a randomized-controlled design with stratified-random sampling, 1000 students (approximately 50/school) of 9th grade from 20 randomly selected schools (representing all socio-economic classes and school-types) and their caregivers (preferably mothers) will be recruited. Objectives of the study will include: estimation of the baseline burden and post-interventional change in cardiovascular risk-factors, related knowledge, perception and practice among participants in Kolkata. Data collection: After obtaining appropriate consent (assent for adolescents), collection of the questionnaire-based data (regarding cardiovascular disease/risk-factor related knowledge, perception, practice), anthropometric measurements, stress assessment and cardiological check-up (pulse and blood pressure measurement along with auscultation for any abnormal heart sounds) will be conducted for each participating students twice at an interval of six months. In between 6 educational sessions will be administered in 10 of the 20 schools randomized to the intervention arm. After the follow-up data collection, same sessions will be conducted in the non-interventional schools. Data analyses and deliverable: Descriptive and inferential analyses (using SAS 9.3) will be conducted to determine the distribution of the risk-factors and efficacy of the intervention in minimizing them so that policy-making can be guided appropriately to keep the adolescents healthy in their future life

NBD-isocolcemid-tubulin interaction: a novel one-step reaction involving no conformational adjustment of reactants

Isocolcemid, a colcemid analogue in which the positions of the C-ring methoxy and carbonyl are exchanged, is virtually inactive in binding to tubulin and inhibiting the formation of microtubule assembly. We have found that the substitution of a NBD group in the side chain of the B-ring of isocolcemid can reverse the effect of these structural alterations (at the C-ring) and the newly synthesized NBD-isocolcemid restores the lost biological activity. It inhibits microtubule assembly with an IC50 of 12 &#956;M and competes efficiently with [3H]colchicine, for binding to tubulin. NBD-isocolcemid has two binding sites on tubulin; one is characterized by fast binding, whereas the binding to the other site is slow. These two sites are independent and unrelated to each other. Colchicine and its analogues compete with NBD-isocolcemid for the slow site. Association and dissociation rate constants for the fast site, obtained from the stopped-flow measurements, are (7.37 &#177; 0.70) &#215; 105 M-1 s-1 and 7.82 &#177; 2.74 s-1, respectively. While the interaction of colchicine and its analogues with tubulin involves two steps, NBD-isocolcemid bindingto tubulin at the slow site has been found to be a one-step reaction. This is evident from the linear dependence of the observed rate constant (kobs) with both NBD-isocolcemid and tubulin concentrations. The interaction of NBD-isocolcemid with tubulin does not involve the conformational change of NBD-isocolcemid, as is evident from the unchanged CD spectra of the drug. The absence of enhanced GTPase activity of tubulin and the native-like protease cleavage pattern of the NBD-isocolcemid-tubulin complex suggest an unaltered conformation of tubulin upon NBD-isocolcemid binding to it as well. Implications of this on the mechanism of polymerization inhibition have been discussed

Synthesis and Study of Palladium(II) and Platinum(II) Complexes Supported by a Common "Wingtip" N-Heterocyclic Carbene

Two annulated imidazolium salts, 2-(phenyl)imidazo[1,5-a]pyridin-4-ylium hexafluorophosphate 1 center dot H(PF6) and 1-methyl-2-(phenyl)imidazo[1,5-a]pyridin-4-ylium hexafluorophosphate 2 center dot H(PF6), were synthesized via formylative cyclization of the corresponding Schiff bases followed by anion metathesis with KPF6. Independently treating 1 center dot H(PF6) or 2 center dot H(PF6) with silver oxide and then palladium chloride in acetonitrile led to the formation of the complexes [Pd(1)(2)Cl(CH3CN)]PF6 (1a) and [Pd(2)(2)Cl(CH3CN)]PF6 (2a), respectively. Likewise, [Pt(1)(2)Cl(CH3CN)]PF6 (1b) and [Pt(2)(2)Cl(CH3CN)]PF6 (2b) were synthesized using similar transmetallation chemistry. The complexes were characterized using various spectroscopic techniques and the solid state structures of 1-H(PF6) as well as 2a were elucidated using X-ray diffraction analyses. A series of DFT calculations were also performed to gain further insight into the respective structures of the complexes. Complexes 1a and 2a were found to facilitate Suzuki coupling reactions under relatively mild conditions.© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei