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Biomedical subjects

V Pandey

Publications and source records attributed to V Pandey.

12 recordsLinked to original sources
PubMed2003

Training for infrainguinal bypass surgery.

BACKGROUND: Despite satisfactory results for surgery performed by trainees, vascular surgeons need to improve training methods to ensure that aspiring surgeons are adequately trained with less clinical exposure during fewer dedicated years of training. OBJECTIVES: To review the wide range of workshop, laboratory and seminar-room based methods available to train for the diverse range of skills required for distal arterial revascularisation. Training methods include anastomotic suturing skills with bench-top training apparatus, working with realistic plastic models and prosthetic conduits, cadaveric dissections and virtual-reality simulations. Many of these also provide excellent opportunities for objective assessment of technical skills and trainees' progress. DESIGN AND METHODS: A review of the literature on surgical education, surgical skills training and assessment. An evaluation of some of the apparatus, facilities, training curricula and courses, currently available to European trainees, is carried out. CONCLUSIONS: Many methods are now available to allow focused training for particular skills in non-clinical settings. Objective tools are also available that allow assessment of trainees at many levels or practicing surgeons. These technical skills assessment methods are important for trainees and surgeons who, in the future, will increasingly need to demonstrate competence in vascular surgery.

Clinical Competence↗
PubMed2001

Differential antioxidative responses to cadmium in roots and leaves of pea (Pisum sativum L. cv. Azad).

Pea (Pisum sativum L. cv. Azad) plants exposed to 4 and 40 microM of Cd for 7 d in hydroponic culture were analysed with reference to the distribution of metal, the accumulation of biomass and the metal's effects on antioxidants and antioxidative enzymes in roots and leaves. Cd-induced a decrease in plant biomass. The maximum accumulation of Cd occurred in roots followed by stems and leaves. An enhanced level of lipid peroxidation and an increased tissue concentration of hydrogen peroxide (H2O2) in both roots and leaves indicated that Cd caused oxidative stress in pea plants. Roots and leaves of pea plants responded differently to Cd with reference to the induction of enhanced activities of most of the enzymes monitored in the present study. These differential responses to Cd were further found to be associated with levels of Cd to which the plants were exposed. Cd-induced enhancement in superoxide dismutase (SOD) activity was more at 40 microM than at 4 microM in leaves. While catalase (CAT) prominently increased in leaves both at 4 and 40 microM Cd, ascorbate peroxidase (APX) showed maximum stimulation at 40 microM Cd in roots. Enhancement in glutathione reductase (GR) activity was also more at 40 microM than at 4 microM Cd in roots. While glutathione peroxidase (GPOX) activity decreased in roots and remained almost unmodified in leaves, glutathione S-transferase (GST) showed pronounced stimulation in both roots and leaves of pea plants exposed to 40 microM Cd. Increased activities of antioxidative enzymes in Cd-treated plants suggest that they have some additive function in the mechanism of metal tolerance in pea plants.

Antioxidants↗
PubMed2000

Immediate and neurotoxic effects of HIV protein gp120 act through CXCR4 receptor.

Primary rat hippocampal neurones show pronounced elevations of intracellular calcium within minutes of exposure to the HIV coat protein gp120. Culture of hippocampal neurones with gp120 causes significant neurotoxicity. We find that the peptide VSLSYRCPCRFF, a competitive inhibitor of the CXCR4 chemokine receptor, markedly inhibits toxicity and eliminates the acute calcium elevation. CXCR4 receptors are thought to signal to the Gi/Go family of trimeric GTP binding proteins. Pretreatment of hippocampal neurones with pertussis toxin to inactivate Gi/Go proteins markedly reduced gp120 neurotoxicity. These results indicate that both short and long term effects of gp120 are the result of activation of the CXCR4 receptor.

Animals↗
PubMed1994

Purification and nucleic acid binding properties of a fragment of type C1/C2 heterogeneous nuclear ribonucleoprotein from thymic nuclear extracts.

A single-strand nucleic acid binding protein (C/F) that has an apparent molecular weight of 12,000 on SDS-polyacrylamide gel electrophoresis and that was originally thought to be the 12-kDa alpha-subunit of the AB form of terminal deoxynucleotidyl transferase (TdT) from calf thymus has been purified and identified as a fragment of the type C1/C2 hnRNP proteins. On the basis of NH2-terminal sequencing and mass spectrometric analysis, C/F contains approximately 94 residues and spans from residue 9 to approximately residue 102 in the type C1/C2 hnRNP proteins. C/F is presumably produced in vitro via limited proteolysis of the type C1/C2 hnRNP proteins following cell disruption. Since C/F corresponds almost exactly to the approximately 90-residue conserved ribonucleoprotein binding domain (RBD) that is shared by many eukaryotic RNA binding proteins, it provided an opportunity to better characterize the domain structure of the type C1/C2 hnRNP proteins and to compare the nucleic acid binding properties of the type C1/C2 and A1 [see Shamoo et al. (1994) Biochemistry, preceding paper in this issue] RNA binding domains. Like the type A1 RBD, the type C1/C2 RBD has an apparent occluded site size of 6-7 nucleotides. The type C1/C2 RBD binds non-cooperatively to homopolynucleotides and has preferential affinity for RNA and for single as opposed to double-stranded nucleic acids. The type C1/C2 RBD has about a 100-fold higher affinity than the type A1 RBD does for RNA and some of this increased affinity results from additional ionic interactions. The latter account for approximately 50% of the free energy of binding of the type C1/C2 RBD. While the type C1/C2 hnRNP proteins exist in vivo as a very tight tetramer with the structure (C1)3C2 [Barnett et al. (1989) Mol. Cell. Biol. 9, 492-498], the isolated type C1/C2 RBD is a monomer. Hence, the determinants for tetramerization appear to lie outside the type C1/C2 RBD. Phenylalanine 19 was identified as the only point of photochemical cross-linking of the type C1/C2 RBD to [d(T)]8. This residue corresponds to the major site of cross-linking of the A1 RBD to [d(T)]8 [Merrill, B. M., Stone, K. L., Cobianchi, F., Wilson, S. H., & Williams, K. R. (1988) J. Biol. Chem. 263, 3307-3313].(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

Amperometric enzyme sensor for glucose based on graphite paste-modified electrodes.

Amperometric enzyme electrode for glucose is described based on the incorporation of glucose oxidase (GOD) into graphite paste modified with tetracyanoquinodimethane (TCNQ). The incorporated enzyme exhibits high activity and long-term stability over the earlier TCNQ-based glucose sensor (1). The sensor provides a linear response to glucose over a wide concentration range. The response time of the sensor is 15-50 sec, and the detection limit is 0.5 mM. Stable response to the substrate was obtained during a period of 35 d. Application of the sensor in the plasma analysis is reported.

Biosensing Techniques↗
PubMed1990

Effect of cement dust on the growth and yield of Brassica campestris L.

Plants of Brassica campestris L. var. G-S20 were treated with cement dust, at rates of 3 (B(1)), 5 (B(2)) and 7 (B(3)) gm(-2) day(-1) for 90 days. Treated plants showed a consistent reduction in growth, photosynthetic pigments, yield and oil content over control plants. The overall phytomass of treated plants was significantly decreased, the maximum reduction being 64.8% in B(3) plants, followed by B(2) plants (55.3%) and B(1) plants (43.69%) at 60 days. The effect on oil content was also greatest in B(3) plants, where it was decreased by 6.13%.

Journal Article↗
PubMed1988

Biochemistry of terminal deoxynucleotidyltransferase. Affinity labeling and identification of the deoxynucleoside triphosphate binding domain of terminal deoxynucleotidyltransferase.

Using the technique of UV-mediated cross-linking of nucleotides to their acceptor sites (Modak, M. J., and Gillerman-Cox, E. (1982) J. Biol. Chem. 257, 15105-15109), we have labeled calf terminal deoxynucleotidyltransferase (TdT) with [32P]dTTP. The specificity of dTTP cross-linking at the substrate binding site in TdT is demonstrated by the competitive inhibition of the cross-linking reaction by other deoxynucleoside triphosphates, and ATP and its analogues, requiring concentrations consistent with their kinetic constants. Tryptic peptide mapping of the [32P]dTTP-labeled enzyme showed the presence of a single radioactive peptide fraction that contained the site of dTTP cross-linking. The amino acid composition and sequence analysis of the radioactive peptide fraction revealed it to contain two tryptic peptides, spanning residues 221-231 and 234-249. Since these two peptides were covalently linked to dTTP, the region encompassed by them constitutes a substrate binding domain in TdT. Further proteolytic digestion of the tryptic peptide-dTTP complex, using V8 protease, yielded a smaller peptide, and its analysis narrowed the substrate binding domain to 14 amino acids corresponding to residues 224-237 in the primary amino acid sequence of TdT. Furthermore, 2 cysteine residues, Cys-227 and Cys-234, within this domain were found to be involved in the cross-linking of dTTP, suggesting their participation in the process of substrate binding in TdT.

Affinity Labels↗
PubMed1987

Biochemistry of terminal deoxynucleotidyltransferase (TdT): characterization and mechanism of inhibition of TdT by P1, P5-bis(5'-adenosyl) pentaphosphate.

The catalysis of DNA synthesis by calf thymus terminal deoxynucleotidyltransferase (TdT) is strongly inhibited in the presence of Ap5A, while replicative DNA polymerases from mammalian, bacterial, and oncornaviral sources are totally insensitive to Ap5A addition. The Ap5A-mediated inhibition of TdT seems to occur via its interaction at both the substrate binding and primer binding domains as judged by classical competitive inhibition plots with respect to both substrate deoxynucleoside triphosphate (dNTP) and DNA primer and inhibition of ultraviolet light mediated cross-linking of substrate dNTP and oligomeric DNA primer to their respective binding sites. Further kinetic analyses of Ap5A inhibition revealed that the dissociation constant of the Ap5A-enzyme complex, with either substrate binding or primer binding domain participating in the complex formation, is approximately 6 times higher (Ki = 1.5 microM) compared to the dissociation constant (Ki = 0.25 microM) of the Ap5A-TdT complex when both domains are available for binding. In order to study the binding stoichiometry of Ap5A to TdT, an oxidized derivative of Ap5A, which exhibited identical inhibitory properties as its parent compound, was employed. The oxidation product of Ap5A, presumably a tetraaldehyde derivative, binds irreversibly to TdT when the inhibitor-enzyme complex is subjected to borohydride reduction. The presence of aldehyde groups in the oxidized Ap5A appeared essential for inhibitory activity since its reduction to alcohol via borohydride reduction or its linkage to free amino acids prior to use as an inhibitor rendered it completely ineffective.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1987

Purification of high molecular mass species of calf thymus terminal deoxynucleotidyltransferase.

We have developed a simplified column chromatographic procedure for the simultaneous purification of two high molecular mass forms (58 kd and 45 kd) and a standard two subunit 44 kd from of terminal deoxynucleotidyltransferase (TdT) from calf thymus chromatin. The procedure involves high salt extraction of the chromatin fraction followed by successive chromatographies on phosphocellulose, DEAE sephadex, and hydroxylapatite matrices. While all 3 species of TdT comigrate throughout these steps, separation of individual species is achieved on a single stranded DNA agarose column. The combined yield of the 45 kd and 58 kd TdTs is quite high (approximately 8 mg/5000g tissue), 45 kd being the major species (approximately 60%) and the 58 kd constituting about 30%. The 44 kd species containing two subunits usually represents under 10% of the total. All the three forms of TdT showed similar specific activity and preference for purine deoxynucleoside triphosphates (dNTPs). The Km for individual dNTP with all three species of TdT is quite similar and decreases in the order dCTP greater than dTTP greater than dATP greater than dGTP. The Km for both synthetic primer and activated DNA with the 3 TdTs was, in increasing order, two subunit 44 kd less than 45 kd less than 58 kd TdT. Both 58 kd and 45 kd TdT displayed two optima for Mn++ (0.1 mM and 1 mM) and a single sharp optimum for Mg++ (2.5 mM). The two subunit 44 kd TdT exhibited a single but broad optimum for Mn++ (1 mM) and for Mg++ (10 mM).

Animals↗