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Biomedical subjects

K Kumari

Publications and source records attributed to K Kumari.

At least 19 recordsLinked to original sources
PubMed2001

Gall bladder perforation and biliary peritonitis in a young pregnant lady.

A rare event of acute free perforation of gall bladder with biliary peritonitis in a case of calculous cholecystitis in a 28 years old pregnant lady occurring in the absence of the usual factors associated with gall stone disease is reported. The clinical features resembled acute appendicitis and a pre-operative diagnosis could not be made. It is suggested that a thorough attempt should be made to exclude conditions mimicking appendicitis, including those of the biliary system, on finding a normal appendix at emergency appendicectomy without hesitating to convert to full laparotomy if required.

Adult↗
PubMed1999

Kinetic characterization of the recombinant hyaluronan synthases from Streptococcus pyogenes and Streptococcus equisimilis.

The two hyaluronan synthases (HASs) from Streptococcus pyogenes (spHAS) and Streptococcus equisimilis (seHAS) were expressed in Escherichia coli as recombinant proteins containing His6 tails. The accompanying paper has described the purification and lipid dependence of both HASs, their preference for cardiolipin, and their stability during storage (Tlapak-Simmons, V. L., Baggenstoss, B. A., Clyne, T., and Weigel, P. H. (1999) J. Biol. Chem. 274, 4239-4245). Kinetic characterization of the enzymes in isolated membranes gave Km values for UDP-GlcUA of 40 +/- 4 microM for spHAS and 51 +/- 5 microM for seHAS. In both cases, the Vmax profiles at various concentrations of UDP-GlcNAc were hyperbolic, with no evidence of cooperativity. In contrast, membrane-bound spHAS, but not seHAS, showed sigmoidal behavior as the UDP-GlcNAc concentration was increased, with a Hill number of approximately 2, indicating significant cooperativity. The Hill number for UDP-GlcNAc utilization by seHAS was 1, confirming the lack of cooperativity for UDP-GlcNAc in this enzyme. The Km values for UDP-GlcNAc were 60 +/- 7 microM for seHAS and 149 +/- 3 microM for spHAS in the isolated membranes. The kinetic characteristics of the two affinity-purified HAS enzymes were assessed in the presence of cardiolipin after 8-9 days of storage at -80 degreesC without cardiolipin. With increasing storage time, the enzymes showed a gradual increase in their Km values for both substrates and a decrease in Vmax. Even in the presence of cardiolipin, the detergent-solubilized, purified HASs had substantially higher Km values for both substrates than the membrane-bound enzymes. The KUDP-GlcUA for purified spHAS and seHAS increased 2-4-fold. The KUDP-GlcNAc for spHAS and seHAS increased 4- and 5-fold, respectively. Despite the higher Km values, the Vmax values for the purified HASs were only approximately 50% lower than those for the membrane-bound enzymes. Significantly, purified spHAS displayed the same cooperative interaction with UDP-GlcNAc (nH approximately 2), whereas purified seHAS showed no cooperativity.

Binding Sites↗
PubMed1997

Molecular cloning, expression, and characterization of the authentic hyaluronan synthase from group C Streptococcus equisimilis.

We previously reported the first cloning of a functional glycosaminoglycan synthase, the hyaluronan synthase (HAS) from Group A Streptococcus pyogenes (spHAS) (DeAngelis, P. L., Papaconstantinou, J., and Weigel, P. H. (1993) J. Biol. Chem. 268, 19181-19184). Group A spHAS was unrelated to a putative Group C HA synthase reported by others (Lansing, M., Lellig, S., Mausolf, A., Martini, I. , Crescenzi, F., Oregon, M., and Prehm, P. (1993) Biochem. J. 289, 179-184). Here we report the isolation of a bona fide HA synthase gene from a highly encapsulated strain of Group C Streptococcus equisimilis. The encoded protein, designated seHAS, is 417 amino acids long (calculated molecular weight, 47,778; calculated pI, 9.1) and is the smallest member of the HAS family identified thus far. The enzyme migrates anomalously fast in SDS-polyacrylamide gel electrophoresis (approximately 42,000 Da). The seHAS protein shows no similarity (<2% identity) to the previously reported Group C gene, which is not an HA synthase. The seHAS and spHAS protein and coding sequences are 72 and 70% identical, respectively. seHAS is also similar to eukaryotic HAS1 (approximately 31% identical), HAS2 (approximately 28% identical), and HAS3 (28% identical). The deduced protein sequence of seHAS was confirmed by reactivity with a synthetic peptide antibody. Recombinant seHAS expressed in Escherichia coli was recovered in membranes as a major protein (approximately 10% of the total protein) and synthesized very large HA (Mr >7 x 10(6)) in the presence of UDP-GlcNAc and UDP-GlcA. The product contained equimolar amounts of both sugars and was degraded by the specific Streptomyces hyaluronidase. Comparison of the two recombinant streptococcal enzymes in isolated membranes showed that seHAS and spHAS are essentially identical in the steady-state size distribution of HA chains they synthesize, but seHAS has an intrinsic 2-fold faster rate of chain elongation (Vmax) than spHAS. seHAS is the most active HA synthase identified thus far; it polymerizes HA at an average rate of 160 monosaccharides/s. The two bacterial HA synthase genes may have arisen from a common ancient gene shared with the early evolving vertebrates.

Amino Acid Sequence↗
PubMed1995

Antidiabetic and hypolipidemic effects of S-methyl cysteine sulfoxide isolated from Allium cepa Linn.

S-methyl cysteine sulphoxide (SMCS), a sulphur containing amino acid isolated from onion (Allium cepa Linn) showed antidiabetic and antihyperlipidemic effects. Oral administration of SMCS daily at a dose of 200 mg/kg body weight for a period of 45 days to alloxan diabetic rats controlled significantly their blood glucose and lipids in serum and tissues and altered the activities of liver hexokinase, glucose 6-phosphatase and HMG CoA reductase towards normal. The above effects of SMCS were comparable to those of glibenclamide and insulin.

Allium↗
PubMed1994

High-performance liquid chromatography method for the determination of protein-glutathione mixed disulfide.

We have developed an efficient and sensitive method for the quantification of picomole quantities of protein-glutathione and protein-cysteine mixed disulfides in ocular lens. Performic acid oxidation releases glutathione and cysteine from the protein-mixed disulfides as glutathione sulfonic acid and cysteic acid, respectively. The sulfonic acids are derivatized with phenylisothiocyanate, and the phenylthiocarbamyl derivatives are separated by HPLC using a reversed-phase ODS column, equilibrated with 0.14 M sodium acetate, containing 0.1% triethylamine and 6% acetonitrile.

Animals↗
PubMed1994

ATP-dependent transport of glutathione-N-ethylmaleimide conjugate across erythrocyte membrane.

Prevailing controversies regarding the identity and nature of S-(2,4-dinitrophenyl) glutathione (Dnp-SG) and GSSG transport system(s) led us to examine xenobiotic-SG transport from human erythrocytes and into inside-out vesicles (IOV) using N-ethyl-maleimide-glutathione conjugate (NEM-SG) as substrate. Efflux of NEM-SG from intact erythrocytes was linear over a period of 4 h, occurred against a concentration gradient, and required energy. No transport of NEM-SG was observed when endogenous ATP was exhausted by preincubation of the erythrocytes for 8 h at 37 degrees C in the absence of glucose. When cellular GSH was partially conjugated with NEM to form 1.5 and 1.0 mM NEM-SG, and the remaining GSH was oxidized with t-butylhydroperoxide to generate 0.2 and 0.4 mM GSSG, respectively, the extrusion of NEM-SG from erythrocytes was not inhibited. The kinetics of NEM-SG transport in intact erythrocytes were monophasic; the Km NEM-SG was 0.62 mM +/- 0.24. However, in IOV two components of NEM-SG transport with respect to NEM-SG and ATP were discernible. The low Km for NEM-SG was 5.6 +/- 1.51 microns with a Vmax of 7.30 +/- 0.69 nmol/mg protein/h and the high Km for NEM-SG was 1.35 +/- 0.14 mM with a Vmax of 65.1 +/- 3.5 nmol/mg protein h. With respect to ATP, the NEM-SG transport had a low Km of 0.12 +/- 0.004 mM and a high Km of 0.52 +/- 0.052 mM. Both components of NEM-SG transport were inhibited by fluoride, o-vanadate, p-hydroxymercuribenzoate and 5,5'-dithiobis(2-nitrobenzoic acid). However, NEM (1 mM) inhibited only the high Km transport. GSH stimulated the low Km transport 1.7-fold. Both low and high Km components of NEM-SG transport significantly declined when ATP was substituted with CTP, UTP, or GTP. GSSG and Dnp-SG competitively inhibited the low Km NEM-SG transport (Ki = 18.5 +/- 2.9 and 1.32 +/- 0.16 microns, respectively) whereas the high Km transport was inhibited by Dnp-SG but not by GSSG. These findings suggest that glutathione S-conjugates may be transported out of erythrocytes by both the high and the low Km mechanisms, the latter being shared by GSSG.

Adenosine Triphosphate↗
PubMed1994

Influence of different factors on the adsorption of carbofuran (2, 3-dihydro-2,2-dimethyl-7-benzofuranyl-N-methyl carbamate) on soils.

The effects of exchangeable cations (H+ and Na+), autoclaving, organic matter, cationic and anionic surfactants, and temperature on the adsorption of carbofuran on two different types of soils were studied. The adsorption isotherms for all effects/treatments were in close agreement with the Freundlich equation and yielded S-shaped isotherms. The amount of carbofuran adsorbed in all cases was higher in Jhansi red loam soil than in Pilibhit sandy loam soil and was related to organic matter content, clay content, CaCO3 content, surface area, and cation-exchange capacity of the soils. The adsorption on soils from both sites follows the order H soil-->Na soil-->natural soil at 25 degrees C-->autoclaved soil-->soil from which organic matter had been removed-->cationic surfactant-->anionic surfactant-->natural soil at 50 degrees C and was in accordance with Freundlich constant K values and distribution coefficient Kd values. The adsorptive capacity of carbofuran for organic matter and clay content for both the Jhansi and the Pilibhit soils was also evaluated by calculating Kom and Kc values, and it was found that the carbofuran adsorption was better correlated with clay content than with organic matter content of soils. On the basis of adsorption isotherms, various thermodynamic parameters such as the thermodynamic equilibrium constant Ko, standard free energy (delta G zero) changes standard ethalpy (delta H zero) changes, and standard entropy (delta S zero) changes have been calculated in order to predict the nature of isotherms.

Adsorption↗
PubMed1993

Low and high Km forms of dinitrophenylglutathione-stimulated ATPase in bovine lens.

Dinitrophenyl S-glutathione (Dnp-SG) ATPase which catalyses the hydrolysis of ATP in the presence of GSH-conjugates has been implicated previously in the transport of these conjugates. In the present studies we demonstrate that Dnp-SG ATPase is present in bovine lens epithelium and cortex. The specific activity per mg membrane protein was found to be 75-fold higher in the epithelium as compared to the cortex. No enzyme was detected in the nuclear region of the lens. Dnp-SG ATPase was purified from bovine lens epithelium and cortex using Dnp-SG-Sepharose 6MB affinity chromatography. The partially purified Dnp-SG ATPase had two distinct Km values, 120 microM and 1.0 mM. The antibodies raised against human erythrocyte Dnp-SG ATPase cross-reacted with the bovine lens epithelium Dnp-SG ATPase which was identified by Western blot as a band corresponding to an approximate M(r) value of 80,000 Da.

Adenosine Triphosphatases↗
PubMed1993

Susceptibility of different rat tissues to non-enzymatic protein glycosylation in experimental diabetes.

Hyperglycemia was induced in Sprague-Dawley rats by alloxan and maintained for 2, 6 and 10 weeks without insulin treatment. Levels of glycosylated plasma proteins, hemoglobin and glycosylated tissue proteins of aorta, heart, kidney, liver and brain were estimated at these intervals. Protein glycosylation was observed to increase linearly as a function of period of hyperglycemia in all the tissues studied, except brain, in the following order: aorta > heart > kidney > liver. Protein glycosylation, leading to formation of covalently modified advanced glycosylated products and protein-protein adducts, may reflect disposition of these tissues to diabetic complications.

Animals↗
PubMed1991

Monoaminoguanidine prevents sorbitol accumulation, nonenzymatic protein glycosylation and development of kidney lesions in diabetic rats.

Monoaminoguanidine administration (25 mg/kg b.wt, i.p. for 14 weeks) to alloxan diabetic rats (blood glucose greater than or equal to 250 mg/dl) decreased the nonenzymatic protein glycosylation and sorbitol levels. It prevented development of Armanni-Ebstein tubular lesions, pathological changes in the glomerular capillary tufts and glomerular basement membrane thickening in the kidney.

Animals↗
PubMed1991

Inhibition of diabetes-associated complications by nucleophilic compounds.

Mono- and diaminoguanidine inhibited ambient glucose-induced glycosylated end product formation of albumin and collagen 125I-labeled albumin covalent binding in vitro. Diaminoguanidine was a stronger inhibitor than monoaminoguanidine. These compounds also inhibited rat eye lens aldose reductase activity in vitro noncompetitively with respect to NADPH with Ki = 30.6 mM for monoaminoguanidine and Ki = 12.5 mM for diaminoguanidine. When administered daily for 98 days at a dose of 25 mg/kg body wt i.p., both compounds lowered eye lens sorbitol and aldose reductase activity in normoglycemic and alloxan-induced diabetic rats. Again, diaminoguanidine was a better inhibitor. Daily long-term administration of mono- and diaminoguanidine (25 mg/kg body wt i.p.) inhibited and prevented experimental diabetes-induced lens opacity in rats, respectively. It appears that diaminoguanidine has a better therapeutic potential in controlling diabetic complications.

Aldehyde Reductase↗
PubMed1990

Interaction of human alpha fetoprotein with bilirubin.

Human alpha fetoprotein (AFP) binds bilirubin with an affinity somewhat lower than albumin. Free bilirubin was found to have an extinction maximum at 440 nm with an extinction coefficient of 4.97 x 10(4) M-1cm-1. AFP binding with the bile pigment elicits a blue shift while albumin interaction produced red spectral shift.

Bilirubin↗