Spatio-temporal evolution of magnetohydrodynamic blood flow and heat dynamics through a porous medium in a wavy-walled artery.

BACKGROUND AND OBJECTIVE: In a healthy body, the elastic wall of the arteries forms wave-like structures resulting from the continuous pumping of the heart. The systolic and diastolic phases generate a contraction and expansion pattern, which is mimicked in this study by considering a wavy-walled arterial structure. A numerical investigation of the spatio-temporal flow of blood and heat transfer through a porous medium under the action of magnetic field strength is conducted. METHOD: The governing equations of the blood flow in the Darcy model are simulated by applying a vorticity-stream function formulation approach. The transformed dimensionless equations are further discretized using the finite difference method by developing the Peaceman-Rachford alternating direction implicit (P-R ADI) scheme. RESULTS: The computational results for the axial velocity, temperature distribution, flow visualization using the streamlines and vorticity contours, isotherms, wall shear stress and the average Nusselt number are presented graphically for different values of the physical parameters. CONCLUSIONS: The study shows that the axial velocity increases with an increase in the Darcy number, and a similar phenomenon is observed because of an amplitude variation in the wavy wall. Both temperature and wall shear stress decreases with an increase in the Darcy number. The average Nusselt number increases with the magnetic field strength, while it has a reducing tendency due to the permeability of the porous medium.

Serosurveillance of rabies antibodies in dogs in Mumbai region by using indirect ELISA.

Rabies is a highly fatal viral infection of the central nervous system affecting all warm-blooded animals including humans. To implement the preventive and control measures, it is important to decide the status of anti-rabies antibodies in dogs. Out of 120 serum samples, 47 (39.2 %) serum samples, showed an antibody titre equal to or above the cut off value of 0.5 IU/ml. The maximum number of dogs showed anti-rabies antibody titres equal to or above the cut-off value of 0.5 IU/ml after <1 month pre-exposure to the rabies vaccine. In 15 serum samples of pet dogs, we observed 13 (86.66 %) dogs with protective anti-rabies antibody titre. Statistical analysis suggests that the age of the animal had no significant effect on anti-rabies antibody titre in vaccinated pet dogs. The overall low seroprevalence of anti-rabies antibody in stray dogs indicates their susceptibility to rabies infection and thus posing a risk of rabies to other animals and humans.

Characteristics of hazardous airborne dust around an Indian surface coal mining area.

Surface coal mining creates more air pollution problems with respect to dust than underground mining . An investigation was conducted to evaluate the characteristics of the airborne dust created by surface coal mining in the Jharia Coalfield. Work zone air quality monitoring was conducted at six locations, and ambient air quality monitoring was conducted at five locations, for a period of 1 year. Total suspended particulate matter (TSP) concentration was found to be as high as 3,723 microg/m(3), respirable particulate matter (PM10) 780 microg/m(3), and benzene soluble matter was up to 32% in TSP in work zone air. In ambient air, the average maximum level of TSP was 837 microg/m(3), PM10 170 microg/m(3) and benzene soluble matter was up to 30%. Particle size analysis of TSP revealed that they were more respirable in nature and the median diameter was around 20 microm. Work zone air was found to have higher levels of TSP, PM10 and benzene soluble materials than ambient air. Variations in weight percentages for different size particles are discussed on the basis of mining activities. Anionic concentration in TSP was also determined. This paper concludes that more stringent air quality standards should be adopted for coal mining areas and due consideration should be given on particle size distribution of the air-borne dust while designing control equipment.

Assessment of the status of work zone air environment due to opencast coal mining.

In India coal production will have to be increased to meat the energy demand at a very high rate. By 2000 AD the cool production from opencast (O/C) mining will rise to 250 Mt. which will be about 70%of the total coal production. The increasing trend of O/C mining leads to cause air pollution problem. A survey was conducted to assess the status of work zone air envimment due to opencast coal mining in Jharia Coalfield. Keeping in view of place of dust generation air quality monitoring stations were selected. Methodology adapted for sampling and analysis of air pollutants have been described. Four season data revealed that maximum concentration of SPM was observed at dragline section and the next high concentration was at haul roads. At all the locations SPM and RPM concentrations exceeded the permissible limits specified by Indian Pollution Control Board. Shift wise and location wise analysis for getting higher concentration of SO2 and NOx, have been discussed. Wind velocity and directions, mixing heights, ventilation coefficient of the area have been analyzed. Huge dust generation creates vision problem to HEMM operators. The methodology adopted may be utilised on industrial scale for various sites.

Air pollution caused by opencast mining and its abatement measures in India.

Opencast mining dominates coal production in India. A survey was conducted to evaluate its local atmospheric impact. Emissions data were utilised to compute dust generation due to different mining activities. Work zone air quality, ambient air quality and seasonal variations are described revealing high pollution potential due to suspended particulate matter (SPM) and consequent impact on human health. Air pollution control measures involve planning and implementing a series of preventive and suppressive measures in addition to dust extraction systems. Different abatement measures are enumerated. Pollution control by trees, the tolerance of trees to different air pollutants and plant species useful for controlling pollution are also discussed. There is a need for wider application of dust control chemicals on haul roads. Sustainable management of pollution can be achieved by the proper implementation of suggested abatement measures.

Sources of air pollution due to coal mining and their impacts in Jharia coalfield.

Indian coal consumption is about 5.5% of the world and the share of coal as energy went up to 66%. The increasing trend of opencast coal mining lead to release of dust and gaseous pollutants. The Indian reserve of coking coal is mainly located in Jharia coalfield and having reserves upto a depth of 1219m are 19339 Mt. The coalfield is subjected to intensive mining activities and accounts for 30% of the total Indian coal production. Coal mining in Jharia coalfield and the sources of air pollution along with the production of air pollutants have been described. The dust particles act as centres of catalysis for many of the chemical reactions taking place in the atmosphere. Characteristics and effects of the pollutants have been discussed. An estimate of the dust generated and discharged into the atmosphere can be made by using emission factor or prediction type equations. It is disirable that this exercise is to be undertaken in planning stage so that adequate and appropriate mitigating measures can be incorporated into the project at least cost.

TATA box DNA deformation with and without the TATA box-binding protein.

DNA ring closure methods have been applied to TATA box DNA and its complex with the TATA box-binding protein (TBP). The J factors for cyclization (effective concentrations of one DNA end about the other) have been measured using cyclization kinetics, with and without bound TBP, for 18 DNA constructs containing the adenovirus major late promoter TATA box (TATAAAAG) separated by a variable helical phasing adapter from sequence-induced A-tract DNA bends. Six phasing lengths were used at three overall DNA lengths each. Cyclization kinetics were also measured in the absence of protein for the same set of molecules bearing a mutant TATA box (TACAAAAG). The results suggest that the TATA box DNA itself is strongly bent and anisotropically flexible, in a direction opposite to the bend induced by TBP, and that the mutant TACA box is much less bent/flexible. The bending and flexibility of the free DNA may govern the energetics of recognition of different DNA sequences by TBP, and the intrinsic bend may act to repress transcription complex assembly in the absence of TBP. The cyclization kinetics of TBP-DNA complexes in solution predict a geometry generally consistent with crystal structures, which show dramatic bending and unwinding. The novel observation of TBP-induced topoisomers suggests that this minicircle approach is able to distinguish TBP-induced unwinding from writhe (these cancel out in larger DNA), and this in turn suggests that changes in supercoiling in small topological domains can control TBP binding.

Interaction of the DNA-binding antitumor antibiotics, chromomycin and mithramycin with erythroid spectrin.

The aureolic acid group of antitumor antibiotics, chromomycin A3 and mithramycin, are well established as transcription inhibitors, which bind reversibly to DNA at and above physiological pH, in the presence of divalent metal ions such as Mg2+. As part of our broad objective to elucidate their intracellular mode of action, other than association with DNA, we studied their interactions with the erythrocyte cytoskeletal protein, spectrin, in the absence and presence of magnesium. Different spectroscopic studies, such as absorbance, fluorescence and CD, have shown that both free chromomycin and mithramycin and their Mg2+ complexes bind to spectrin with an affinity higher than that reported for DNA. The affinity constants for the association of chromomycin and mithramycin (or their Mg2+ complexes) with spectrin are comparable with those for the association of spectrin with other cytoskeletal proteins, for example F-actin, ankyrin, protein 4.1, etc. The nature of the binding of the two antibiotics to spectrin is different. The mode of binding of the antibiotics with spectrin also changes in the presence of Mg2+. The interaction leads to a change in the tertiary structure of the protein. The relevance of the results to our understanding of the mode of action of the antibiotics is discussed.

Membrane interaction of an antitumor antibiotic, mithramycin, with anionic phospholipid vesicles.

Small unilamellar vesicles (SUV) composed of zwitterionic phosphatidylcholine and two different anionic phospholipids, phosphatidic acid and phosphatidylserine, in different compositions, were employed to study the membrane interaction of an antitumor antibiotic, mithramycin (MTR). Binding of MTR to dimyristoylphosphatidylcholine (DMPC) liposomes containing the anionic phospholipid dimyristoylphosphatidic acid (DMPA) was estimated by measuring the increase in intensity of the intrinsic fluorescence of MTR with increasing concentrations of phospholipids. Membrane perturbations were observed in acidic SUV of DMPC/DMPA and DMPC/bovine brain phosphatidylserine by MTR and its magnesium complex as studied by monitoring the leakage of the entrapped fluorescent marker carboxyfluorescein and by electron microscopic measurements of the size of the liposomes. These results indicated a possible role of anionic phospholipids in mediating binding of MTR and its magnesium complex to the cell surface membranes before reaching the target DNA.

Differential interactions of the Mg2+ complexes of chromomycin A3 and mithramycin with poly(dG-dC) x poly(dC-dG) and poly(dG) x poly(dC).

The interaction of the two anticancer antibiotics, chromomycin A3 and mithramycin, with the polynucleotides poly(dG-dC) x poly(dC-dG), representative of B-DNA, and poly(dG) x poly(dC), representative of A-DNA, in the presence of Mg2+ is studied by spectroscopic techniques such as absorbance, fluorescence, and dircular dichroism (CD). The studies were done with both drug x Mg2+ complexes, I and II, having 1:1 and 2:1 stoichiometries with respect to drug and Mg2+, respectively [Aich, P., Sen, R., & Dasgupta, D. (1992) Biochemistry 31, 2988-2997]. The objective of the present work is 2-fold. First, an attempt is made to understand the structural basis of the ligand-DNA interaction, particularly the role of DNA backbone conformation with its groove size and the accessibility of the 2-amino group in the minor groove of guanosine. Second, the role of the antibiotic saccharide moieties in the association with DNA was studied. For this purpose, the spectroscopic characterization of the binding was done followed by the evaluation of binding parameters and associated thermodynamics. Analysis of the observed thermodynamics for the ligand-DNA interactions in terms of the different structures of the polynucleotides was done. The salient results are as follows. Complex I does not discriminate significantly among the A- and B-forms of DNA when it binds to them in an entropy-driven process. On the other hand, complex II for both drugs recognizes B- and A-forms of DNA in different ways. This observation implies that the sequence specificity shown by this complex is a sequel to the difference in the parameters such as groove size and accessibility of the guanosine amino group. Another important finding is that binding with the same polynucleotide is not comparable for the complex II of the two drugs. It emphasizes the involvement of the sugar moieties, when the drug x Mg2+ complex binds to DNA. The presence of an acetoxy group in the sugars of chromomycin A3 imparts some distinctive specific features of the association of the chromomycin dimer x Mg2+ complex with DNA. Finally, the results are compared with those available from NMR studies of different drug-oligonucleotide complexes under conditions where complex II is the ligand.

A DNA-binding antitumor antibiotic binds to spectrin.

Aureolic acid group of antibiotics inhibit transcription by reversible binding to DNA in presence of divalent magnesium. We for the first time report binding of the one of such antitumor antibiotic, mithramycin (MTR), to the major protein component of erythrocyte cytoskeleton, spectrin. A reasonably high apparent dissociation constant was estimated to be 1.5 microM. The binding of mithramycin in the absence of any divalent cation to the large cytoskeletal protein led to quenching in the tryptophan fluorescence of the protein. Stern-Volmer quenching of the tryptophan residues by acrylamide revealed conformational change in the MTR-bound spectrin. This preliminary study might be useful in understanding other possible sites of actions after translocation.