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Biomedical subjects

B V Kumar

Publications and source records attributed to B V Kumar.

At least 19 recordsLinked to original sources
PubMed2005

Prevalence of Candida in the oral cavity of diabetic subjects.

OBJECTIVE: Estimation of prevalence of Candida in the oral cavity of diabetic and non-diabetic subjects. MATERIAL AND METHODS: One hundred and three subjects of diabetes mellitus (49 Type 1 diabetes mellitus and 54 Type 2 diabetes mellitus) and one hundred non-diabetic subjects (control) were studied. RESULTS: 41(83.67%) out of 49 Type 1 diabetes mellitus, 37(68.52%) out of 54 Type 2 diabetes mellitus and 27(27%) out of 100 in non-diabetic subjects were found to carry Candida in their oral cavity. Colony Forming Unit (CFU) of Candida in the oral cavity ranking in groups was Type 1 diabetes mellitus > Type 2 diabetes mellitus > non-diabetic subjects. CONCLUSION: Colonization and carriage of Candida in the oral cavity was found to be higher in diabetic subjects than in non-diabetic subjects. However anti-diabetic therapy and glycaemic control in diabetes were found to bear no relation with carriage of Candida in the oral cavity.

Candida↗
PubMed1996

Hemodynamics in aneurysm.

A numerical simulation of hemodynamics in blood vessels with 0-75% dilation is made. A transient UVP finite element method (FEM) and a stable time integration scheme, based on a predictor-corrector strategy, with constant error monitoring are employed in the flow analysis. The pulsatile flow is analyzed without any assumptions in nonlinear terms and is characterized by thoroughly analyzing the flow, pressure, and stress fields. The central axis velocity, central axis and wall pressures, pressure gradient history, and wall shear stress are influenced by the presence of aneurysm. Time-dependent recirculation regions which are sensitive to the degree of dilation of the vessel are seen in the concavity of the dilation. The transverse velocities and their variations with time are found to be too significant to be neglected. The effects of nonlinear convective terms and the nonlinear geometry of the vessel are clearly depicted through the transverse velocity and pressure profiles.

Algorithms↗
PubMed1995

Finite element analysis of nonlinear pulsatile suspension flow dynamics in blood vessels with aneurysm.

A nonlinear pulsatile suspension flow in a dilated vessel is numerically analysed. Two sets of highly coupled nonlinear partial differential equations governing the suspension flow are numerically solved, to simulate the suspension flow dynamics. A transient velocity-pressure (UVP) finite element method (FEM) and a stable time integration scheme, based on a predictor-corrector strategy, with constant error monitoring are employed in the flow analysis. The pulsatile suspension flow is characterized by analysing the flow, pressure and stress fields. Effects of the nonlinear particulate phase on the nonlinear suspending fluid phase are brought out by comparing the suspension flow results with those of homogeneous flow. Particles are seen to dampen the flow velocity, wall and central axis pressure, pressure gradient and wall shear stress. time-dependent recirculation regions which are sensitive to the presence of particles are seen in the dilated portion of the vessel. These recirculation regions favour thrombogenesis. The nonlinear effects due to the vessel geometry and those due to the convective terms dominate the dampening effect of the particles. These nonlinear effects are depicted through the transverse velocity and pressure plots. Wall shear stresses of suspension flow are not only high but also alternate in direction.

Algorithms↗
PubMed1995

Purification and identification of two distinct isoforms of rabbit pancreatic cholesterol esterase.

Cholesterol esterase (CEases; E.C. 3.1.13) has been purified to homogeneity from rabbit pancreas. The method of purification consists of homogenization of total pancreas, high speed centrifugation, anion exchange column chromatography on S-Sepharose, size exclusion on Sephacryl followed by affinity chromatography on heparin agarose. During the purification procedure, two distinct isoforms of CEases have been identified. Both forms are similar in their molecular weights, bile salt requirement and pH optima but differ in their sensitivity to heparin. Isoform-I is resistant and isoform-II is sensitive to heparin. In the normal pancreas of the adult rabbit, the amount of each of the enzymes appears to be in equimolar concentrations. Physiological significance of the existence of heparin sensitive and resistant forms by the same tissue is unclear. In view of the significant role played by heparin in the modulation of CEase activity and several other physiological functions, these two isoforms may have different mechanisms of action on the hydrolysis of carboxyl esters of cholesterol and vitamins.

Animals↗
PubMed1993

Molecular cloning and expression of rabbit pancreatic cholesterol esterase.

Rabbit pancreatic cholesterol esterase (CEase, carboxyl ester lipase, EC 3.1.1.3) has been cloned from a lambda gt11 library of adult rabbit pancreatic cDNA. The open reading frame consists of 1788 nucleotides which encodes 576 amino acids of the functional protein and a 20 amino acid leader peptide. When compared to other species, the greatest homology is observed between residues 82-248 with little or no homology at the C-terminal end where proline-glutamate-serine-threonine (PEST) segments are a characteristic feature of the human CEase. Rabbit CEase (RCEase) retains the active-site serine (gxsxg), the active-site histidine and the tentative heparin binding site (KKRCLQ) at similar positions in comparison to pancreatic CEases of other species. When rabbit CEase cDNA is expressed in monkey kidney (COS-7) cells, enzymatic hydrolytic activity is detected in the growth medium as is a 67 kDa protein by Western blotting with polyclonal anti-CEase antibody. Northern blot analysis shows two mRNA (2.2 and 3.2 kb) species.

Amino Acid Sequence↗
PubMed1993

Ultrastructural changes in the efferent duct and epididymis of men with obstructive infertility.

Ultrastructural changes in the efferent duct and in different regions of the epididymis in men with obstructive azoospermia were compared with corresponding tissues collected from men of proven fertility who underwent castration due to malignancy of the prostate. Major degenerative changes were seen in the efferent duct and the caput epididymidis of men with obstruction at the caput epididymidis which may have been induced by fluid pressure due to defective absorption of testicular fluid in the caput epididymidis. These degenerative changes included decrease in tubular and lumen diameter of the caput and the cauda epididymides, decrease in height of the stereocilia, reduction in rough endoplasmic reticulum and Golgi material, and presence of lipofuscin and osmiophilic dense bodies. The degenerative changes were less when the site of obstruction was in the cauda epididymidis since fluid reabsorption would continue to take place normally in the caput epididymidis. In men who had undergone vasoepididymostomy (VEA), the ejaculated spermatozoa showed a high percentage of morphological abnormalities which may have occurred due to adverse effects of long-term obstruction on spermatogenesis.

Adult↗
PubMed1992

Cloning, nucleotide sequence, and chromosome localization of the human pleiotrophin gene.

Pleiotrophin (PTN), midkine (MK), and retinoic acid-induced heparin-binding (RI-HB) protein are members of a recently discovered family of developmentally regulated cytokines. We report here the cloning, sequencing, chromosomal localization, and structural organization of the genomic version of the human PTN gene and its comparison to the mouse MK gene. The PTN gene was found to be arranged in five exons and four introns, in a fashion similar to that of the mouse MK gene. Exon 1, as for MK, does not appear to encode amino acid sequence. As in the case of the MK gene, exon 2 encodes the hydrophobic leader sequence of PTN, which constitutes the beginning of gene translation. The signal peptide cleavage site of both genes lies toward the 3' end of exon 2. Exons 3 and 4 of PTN were most closely related to exons 3 and 4 of the MK gene; in particular, six of the ten cysteine residues were coded for in exon 3 and the remaining 4 in exon 4. The intron-exon splice junctions of both genes occurred through the same residues. The two genes were found to be less closely related in the fifth exon which encodes the highly basic C-terminal domains, the translation termination codon, and the polyadenylation signal of both cDNAs. We also report approximately 2000 bp of the 5' untranslated sequence of the PTN gene and the site of initiation of transcription in human placenta. PTN was localized to human chromosome 7q33-34 by fluorescence in situ hybridization. These data confirm the existence of a new gene family of developmentally regulated cytokines.

Amino Acid Sequence↗
PubMed1992

Structure of the human pancreatic cholesterol esterase gene.

The gene for human pancreatic cholesterol esterase consists of 11 exons and 10 introns and is 9.2 kb in length. The last and longest exon (841 nucleotides) is unique to the human gene. Functional amino acids are encoded on separate exons. The leader sequence is encoded by a single exon which carries two additional N-terminal amino acids of the mature functional protein. A positive TATA element is identified 43 nucleotides from the start codon. Pulse-field gel electrophoresis and hybridization with various cDNA probes and direct sequence data revealed the existence of a CEase-like gene. Partial sequence analysis of this gene from a human cosmid library and human genomic DNA showed a premature stop signal in exon 10, shortly after the codon for the active-site histidine. Both the functional gene and the CEase-like gene have a polyadenylation signal in the 3'-untranslated region. Thus, the complex gene structure for this intestinally active enzyme may provide in part a potential molecular explanation for the well-known heterogeneity of the intestinal absorption of cholesterol.

Base Sequence↗
PubMed1992

Neuroanatomy of Cysticercus cellulosae (Cestoda) as revealed by acetylcholinesterase and nonspecific esterase histochemistry.

The nervous system of Cysticercus cellulosae, the metacestode stage of the tapeworm Taenia solium, was delineated using histochemical methods for the localization of the enzyme markers; nonspecific esterase and acetylcholinesterase. The main features of the nervous system include a pair of cerebral ganglia, a circumcerebral nerve ring, a rostellar nerve ring, and anterior and posterior nerves and their branches. The posterior nerves form a subtegumental network in the strobila and the bladder wall. A nerve network around excretory tubules could also be demonstrated, suggesting neuronal control of excretion in the metacestode. No sheath was observed around the nervous system. The morphological features described suggest "cephalization" of the nervous system in this parasite.

Acetylcholinesterase↗
PubMed1992

Dopamine receptors in human foetal brains: characterization, regulation and ontogeny of [3H]spiperone binding sites in striatum.

Eighteen corpora striata from normal human foetal brains ranging in gestational age from 16 to 40 weeks and five from post natal brains ranging from 23 days to 42 years were analysed for the ontogeny of dopamine receptors using [3H]spiperone as the ligand and 10 mM dopamine hydrochloride was used in blanks. Spiperone binding sites were characterized in a 40-week-old foetal brain to be dopamine receptors by the following criteria: (1) It was localized in a crude mitochondrial pellet that included synaptosomes; (2) binding was saturable at 0.8 nM concentration; (3) dopaminergic antagonists spiperone, haloperidol, pimozide, trifluperazine and chlorpromazine competed for the binding with IC50 values in the range of 0.3-14 nM while agonists--apomorphine and dopamine gave IC50 values of 2.5 and 10 microM, respectively suggesting a D2 type receptor. Epinephrine and norepinephrine inhibited the binding much less efficiently while mianserin at 10 microM and serotonin at 1 mM concentration did not inhibit the binding. Bimolecular association and dissociation rate constants for the reversible binding were 5.7 x 10(8) M-1 min-1 and 5.0 x 10(-2) min-1, respectively. Equilibrium dissociation constant was 87 pM and the KD obtained by saturation binding was 73 pM. During the foetal age 16 to 40 weeks, the receptor concentration remained in the range of 38-60 fmol/mg protein or 570-1080 fmol/g striatum but it increased two-fold postnatally reaching a maximum at 5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Structural gene for human membrane cofactor protein (MCP) of complement maps to within 100 kb of the 3' end of the C3b/C4b receptor gene.

The structural gene for membrane cofactor protein (MCP), a widely distributed C3b/C4b binding regulatory glycoprotein of the complement system, has been mapped to the same locus as the structural genes for CR1, CR2, DAF, and C4bp. The order of the genes within an approximately 800-kb DNA fragment on the long arm of chromosome 1 is MCP-CR1-CR2-DAF-C4bp. Further, the MCP gene maps to within 100 kb of 3' end of the CR1 gene.

Antigens, CD↗
PubMed1988

Purification of membranes and identification of phase-specific proteins of the dimorphic pathogenic fungus Histoplasma capsulatum.

Plasma membrane vesicles from the yeast and mycelial phases of Histoplasma capsulatum have been purified and characterized. The method of purification involved differential centrifugation of ballistically fractured cells followed by sedimentation through discontinuous sucrose density gradient and equilibrium centrifugation. Purity of the preparation was assessed by electron microscopy. The protein composition of the membrane preparations from the yeast and mycelial phases of the fungus was analyzed by polyacrylamide gels. A comparison of the two morphologic phases revealed quantitative and qualitative differences in the expressions of several membrane-specific proteins. Physical differences in the appearance of the membranes were also observed by electron micrography of membrane preparations. Alteration in membrane fluidity may be one of the many causes for differences in the appearance of membrane vesicles in the two phases.

Cell Fractionation↗