Biomedical subjects
Publications and source records attributed to R Kumar.
We present a method of repairing inferobasal ventricular septal rupture after myocardial infarction, preserving the ventricular cavity sizes. This may be useful when extensive infarction compromises ventricular geometry with other repair techniques.
Multiple resistance to benzimidazoles (fenbendazole, albendazole and mebendazole) in a strain of Haemonchus contortus in sheep was detected on a farm where fenbendazole resistance had already been identified. Following a faecal egg count reduction test, this was confirmed by both critical and controlled anthelmintic tests. Different groups of sheep infected naturally or given an experimental infection with the fenbendazole-resistant strain were treated with the recommended doses of various anthelmintics. Compared to the control group, percentage reductions in faecal egg counts of sheep treated with fenbendazole, albendazole, mebendazole, levamisole and morantel varied between 56% and 81% and worm counts between 71% and 86%. The results indicate the presence of multiple anthelmintic resistance in this strain of H. contortus on this farm. Sheep treated with ivermectin and closantel showed 100% reductions in faecal egg and worm counts, suggesting high efficacy of these drugs against the population of H. contortus on this farm.
The levels of the lipid peroxidation product malondialdehyde (MDA) and the activity of transaminases and alkaline phosphatases were estimated in the sera of 25 thermally injured patients at various time intervals after injury. The level of MDA was increased during the early postburn period, whereas the activities of transaminases and alkaline phosphatase became elevated later after injury. It is concluded that an increased concentration of lipid peroxidation product (MDA) in the early postburn period may affect the spleen, liver and kidney, resulting in the release of enzymes into blood stream. Such damage may be checked by the antioxidants superoxide dismutase or allopurinol.
The study deals with the analysis of residue of hexachlorocyclohexane (HCH) and its possible damaging potential on testicular plasma membrane of rats. In vitro studies were conducted by exposing plasma membrane of testis with 1.46 x 10(-5) M, 2.92 x 10(-5) M, 4.38 x 10(-5) M, 7.30 x 10(-5) M, 1.46 x 10(-4) M and 2.92 x 10(-4) M HCH at 37 degrees C for 15 min. The results indicate inhibition in the activity of the Ca(2+)-ATPase, Na(+)+K(+)+Mg(2+)-ATPase and 5'Nucleotidase. In vivo studies were carried out following repeated dermal exposure to HCH at a dose level of 50 or 100 mg/kg/day for 60 days to male rats. The results show significant decrease in the activities of 5'-Nucleotidase, Ca(2+)-ATPase, Na(+) + K(+)-ATPase and Mg(2+)-ATPase in the plasma membrane of testis following exposure to HCH. The analysis of the residues of HCH reveals the presence of significant quantities of its different isomers viz., alpha, beta, gamma and delta in the testicular plasma membrane of rats given in vivo dermal exposure of this pesticide. These results suggest that the presence of HCH residue may be a factor in inhibiting the marker enzymes of the plasma membrane of testis.
The application of molecular biology methods has contributed significant insight into the epidemiology of infections caused by Mycobacterium tuberculosis. However, most of the techniques remain out of reach of laboratories in the tropics. We describe here a simple method for extraction of DNA from the pathogen, a first step in the application of molecular biology tools.
OBJECTIVE: To find a practical method of cane length measurement that achieves the elbow flexion of 20 degrees to 30 degrees. DESIGN: Two standard methods of cane length measurements were compared. Method I: Length of the cane measured from the floor to the top of the greater trochanter. Method II: Length of the cane measured from the floor to the distal wrist crease. Using an adjustable cane, each individual was fitted according to the two methods, and elbow angle was measured after each adjustment. Cane length was also correlated with arm length and height. PARTICIPANTS: Fifty-two normal volunteers who were ambulatory without assistive devices. RESULTS: Mean +/- SD of the elbow angle according to Method I and Method II was 44.8 +/- 11.8 and 25.4 +/- 6.1, respectively. A significant difference was found in the elbow angle between the two methods (unpaired two-tailed student t test, p = 5.910(-18)). Of the 52 volunteers, 4 (7.7%) measured according to method I and 49 (94.3%) measured according to method II showed the elbow angle between 20 degrees and 30 degrees. The ideal length of the cane (L) also can be determined by the formula L = H x .45 + .87 meters or A x .76 + .19 meters, where H is the height of the individual in meters and A is the arm length measured in meters. CONCLUSION: Ideally, cane length should be measured from the floor to the distal wrist crease. The length can also be determined using the above formulae.
Albino rats were lesioned bilaterally with 6-hydroxydopamine (6-OHDA) hydrochloride (4 micrograms/microliters, dissolved in saline with 0.1% ascorbic acid) into the striatum, and 72 h after the injection, levels of lipid peroxidation, GSH, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), lipid class, membrane fluidity, and intracellular calcium concentrations were studied and the results were compared with those in the sham-operated controls. The malonaldialdehyde level and the level of conjugated dienes were increased by 43 and 40%, respectively, in corpus striatum, and GSH, SOD, and GSH-Px levels were decreased (24-30%) following 6-OHDA treatment. Total phospholipid content was also decreased (18%), whereas cholesterol content remained unaffected. Among the different phospholipids only phosphatidylcholine and phosphatidylinositol were decreased in level. Membrane fluidity was decreased (23%), whereas the intracellular calcium concentration was elevated (100%) in corpus striatum compared with control rats. The results suggest that these alterations in membrane-related events by 6-OHDA could be due to free radical generation.
An Indian isolate of P. falciparum was propagated in vitro and monoclonal antibodies were raised against this parasite. Of 11 positive hybrids obtained, 3 were cloned and characterized. When tested in IFA with synchronized cultures dominated by mature schizonts, all three monoclonal antibodies showed distinct fluorescent patterns. These three monoclonals reacted with seven of the eight P. falciparum isolates tested. One of these monoclonal antibodies, which showed a fluorescence pattern similar to the merozoite dot fluorescence reported by previous investigators, also inhibited parasite growth in vitro. The antigens that reacted with the monoclonal antibodies have been isolated by using MAb-affinity columns.
UV-induced cyclobutane dimers and 6-4 photoproducts, containing an unmodified nucleotide at the 5'-position were released from DNA by means of digestion with DNase I, snake venom phosphodiesterase and prostatic acid phosphatase. The enzymes were deactivated by proteinase K followed by ethanol precipitation. The products were phosphorylated by polynucleotide kinase and [gamma-32P]ATP. The TLC system used for the analysis enables separation of the different photoproducts and detection at a fmol level. T4 endonuclease treatment was applied to confirm the positions of cyclobutane dimers.
We used high fidelity PCR and constant denaturant capillary electrophoresis (CDCE) [Khrapko et al. (1994) Nucleic Acids Res., 22, 364-369] to separate wild type and different mutant N-ras exon 1 and 2 sequences. The set of plasmids containing N-ras cDNA, wild type or mutant sequences representing all transforming amino acid-substituting single base pair changes in codons 12, 13 (exon 1) and 61 (exon 2), were amplified using Pfu polymerase in a limited cycle polymerase chain reaction. One of the primers used for the amplification of each exon included a 40 nucleotide GC rich sequence that created high and low melting domains. The amplified fragments 151 bp (exon 1) and 150 bp (exon 2) were run on the CDCE with the 'denaturant zone' temperature of the capillary corresponding to the melting temperature of 111 bp (exon 1) and 110 bp (exon 2) low melting domains. The separation was achieved between wild type and mutant sequences as homoduplexes in 15 out of 19 cases, as a single base substitution alters the electrophoretic mobility of a partially melted double stranded fragment. The denaturation and reannealing of wild type and mutant fragments together created wild type/mutant heteroduplexes. All the heteroduplexes were well resolved from wild type homoduplex. In the current form mutant sequences were detected at a frequency of 10(-3) in the presence of wild type. This study has resulted in obtaining electrophoretic spectrum of different N-ras mutants on CDCE as homoduplexes as well as heteroduplexes.
A 32P-postlabelling method is reported for the detection of 7-alkylguanines, the major adducts formed by the reaction of 1,2-alkylepoxides with DNA. Calf thymus DNA was reacted in vitro with different epoxides (ethylene oxide through octylene oxide) and digested with micrococcal nuclease and spleen phosphodiesterase to 3'-nucleotides. The adduct enrichment was carried out by an ion-exchange method and adducts were labelled with [gamma-32]ATP in a T4-polynucleotide kinase-mediated reaction. The labelled adducts, prior to resolution by two-dimensional TLC, were treated with nuclease P1. The recoveries of adducts formed by different epoxides ranged from 3 to 10%, tending to increase with the increase in the chain length of the substitutions. The 32P-postlabelled adducts were also analysed by HPLC coupled with a radioisotope detector. This method has been applied for the detection of 7-alkylguanine adducts in rats exposed to different alkenes. The method has potential for use in measuring human exposure to alkenes or their corresponding epoxides as well as the endogenously formed 7-alkylguanine adducts.
Absorption, distribution, elimination and hemoglobin and DNA adduct formation were studied in the rat after inhalation of individual C2-C8 1-alkenes (olefins) at 300 p.p.m., 12 h a day for 3 consecutive days. The concentrations of olefins were measured in blood, lung, brain, liver, kidney and perirenal fat immediately after each exposure and 12 h after the third exposure. DNA adducts were determined by 32P-postlabeling in liver, and lymphocytes sampled immediately after the last exposure. Hemoglobin adducts were determined by GC/MS and GC/MS/MS in erythrocytes sampled immediately after the last exposure. Concentrations of 1-alkenes in blood and organs reached a steady-state level after the first 12 h exposure, and the concentrations 12 h after the last exposure were generally low, except in fat tissue. Concentrations of 1-alkenes in blood and the different tissues increased with increasing number of carbon atoms. In contrast, levels of hemoglobin and DNA adducts decreased with increasing number of carbon atoms. The decrease was most pronounced from C2 to C3. The decrease through the whole homologous series from ethene to 1-octene was most pronounced for hemoglobin adducts followed by the DNA adducts in the lymphocytes. All 1-alkenes caused formation of detectable levels of hemoglobin and DNA adducts, although the levels of hemoglobin adducts after C4-C8 exposure were low. The project illustrates important aspects of the use of biomarkers. The structure-activity approach gives possibilities for extrapolation within the homologous series.
We explored the regulation of epidermal growth factor (EGF)-mediated activation of EGF receptor (EGF-R) phosphorylation by curcumin (diferuloyl-methane), a recently identified kinase inhibitor, in cultured NIH 3T3 cells expressing human EGF-R. Treatment of cells with a saturating concentration of EGF for 5-15 min induced increased EGF-R tyrosine phosphorylation by 4- to 11-fold and this was inhibited in a dose- and time-dependent manner by up to 90% by curcumin, which also inhibited the growth of EGF-stimulated cells. There was no effect of curcumin treatment on the amount of surface expression of labeled EGF-R and inhibition of EGF-mediated tyrosine phosphorylation of EGF-R by curcumin was mediated by a reversible mechanism. In addition, curcumin also inhibited EGF-induced, but not bradykinin-induced, calcium release. These findings demonstrate that curcumin is a potent inhibitor of a growth stimulatory pathway, the ligand-induced activation of EGF-R, and may potentially be useful in developing anti-proliferative strategies to control tumor cell growth.
A culture-appropriate and simple test battery consisting of 67 test items was developed and field tested in Haryana, India, in 1987-89. Trained field workers administered the tests to 3731 preschool children in 47 randomly selected villages of a district, irrespective of their physical/mental status. Centile age values were constructed for various developmental milestones included in the cultural-appropriate test battery. The locally relevant, simple, and low cost developmental tests and reference values will be used for early detection of developmental disabilities at primary care level.
A community-based inquiry was conducted in a rural area of north India to estimate extent of the problem of birth asphyxia. Births and neonatal deaths were recorded in 54 villages. Trained field workers contacted birth attendants/family members within 15 days after the birth, and recorded the symptoms and signs related to birth asphyxia on a pre-coded questionnaire. Detailed descriptive history of birth events in chronological order was recorded in cases suspected to be asphyxiated or stillborn. Two pediatricians reviewed the case histories independently to assign the diagnosis. Out of the 1977 recorded livebirths, field workers suspected 53 babies to be asphyxiated, 39 of these were diagnosed as asphyxiated, four as not asphyxiated by both the experts, and 10 were considered as asphyxiated by one of the experts. Prevalence of birth asphyxia was estimated to be at least 2 per cent (39/1977). Case fatality in these cases was 74 per cent. The verbal diagnosis method adopted in this study can be used to compare the prevalence of asphyxia in community studies.
A 30-year-old man had severe left anterior knee pain after a trivial injury. A three-phase bone scan diagnosed this condition to be reflex sympathetic dystrophy, which was subsequently confirmed by sympathetic blockade.
OBJECTIVE: To define whether endothelin-1, a peptide produced by injured/ischemic endothelium, has any effect on monocyte intracellular calcium and the production of interleukin (IL)-1 and IL-6. DESIGN: Prospective controlled laboratory study. Human monocytes from healthy donors were assayed for intracellular calcium by fluorometry and were stimulated for 24 hrs in tissue culture with purified endotoxin or endothelin. SETTING: Veterans Affairs Medical Center surgical critical care basic science laboratory. MEASUREMENTS AND MAIN RESULTS: Endothelin-1 increased the intracellular calcium concentration in fura-2 loaded human monocytes to a mean value of 37 +/- 4 nmol. Phytohemagglutinin increased intracellular calcium in control monocytes to a mean value of 97 +/- 12 nmol (n = 15; p < .001). Endothelin had no effect on neutrophil or lymphocyte intracellular calcium. Monocytes incubated with 10(-9) M endothelin significantly increased IL-6 production to values nearly as high as the lipopolysaccharide controls, but did not increase IL-1 production (n = 8; p < .01). CONCLUSION: Endothelin-1 increased intracellular calcium in monocytes and caused production of IL-6.
We recently described postnatal developmental differences of beta-adrenergic- and G-protein-mediated modulation of L-type calcium currents (ICa) in newborn and adult rabbit heart. To extend the results obtained by ICa experiments, we studied developmental changes in modulation of contractility induced by isoproterenol (ISO), forskolin (FOR) and isobutyl-methylxanthine (IBMX), all of which work through the cyclic AMP-dependent pathway. Left ventricular developed pressure (LVDP) and its first derivative (dP/dt) were measured with an intraventricular fluid-filled balloon in isolated adult and newborn (ages 1-3 days) rabbit hearts under Langendorff perfusion. ISO increased LVDP and +/- dP/dtmax dose dependently, with much greater positive inotropic effect on adult than on newborn heart. Concomitant use of a subthreshold concentration of IBMX (0.1 microM), a nonselective phosphodiesterase inhibitor (PDEI), did not significantly potentiate the dose-dependent inotropic effect of ISO in adult heart, but did markedly potentiate such effect in newborn heart. ISO 10 microM and FOR 10 microM had comparable inotropic effects on adult heart, whereas 10 microM ISO had a much weaker inotropic effect than 10 microM FOR on newborn heart. However, the increase in LVDP and +dP/dtmax and the percentage increase in these values induced by 10 microM FOR in newborn heart was still significantly lower than that in adult heart. Newborn heart has less effective signal transduction from beta-adrenergic stimulation (ISO) to increased contractility than does adult heart. Although newborn heart responds more to direct stimulation of adenylyl cyclase activity (FOR) than to beta-adrenergic stimulation, it still has less overall contractile reserve than adult heart. PDE isozymes of newborn heart are much more sensitive to IBMX than are those of adult heart, producing a significant potentiation of ISO effect by low doses of IBMX in newborn, but not adult, heart.