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Biomedical subjects

S C Dhar

Publications and source records attributed to S C Dhar.

At least 37 records · Page 2Linked to original sources
PubMed1991

Toxic effect of dimethoate on the crosslinking of gingival and uteral collagen in female albino rats fed with normal and high protein diets.

The effect of dimethoate on gingival and uteral collagen crosslinking was studied in normal and high protein diets fed female albino rats. The gingival and uteral samples were collected from all the groups of rats and percent reversibility of neutral salt soluble collagen gel and the solubility of insoluble collagen in KCNS or urea were determined. The analysis of gingival and uteral samples showed alpha 1 and alpha 2 sub units of neutral salt soluble collagen appreciably increased beta chains and aldehyde content significantly decreased in dimethoate treated animals compared to controls. The results indicate that due to the effect of dimethoate, the crosslinking and maturation of collagen are impaired.

Animals↗
PubMed1990

Factors influencing extracellular protease synthesis in an Aspergillus flavus isolate.

Our studies on the control of extracellular protease synthesis in an Aspergillus flavus strain isolated by us indicate that in a defined medium a protein must be present for enzyme to be produced. Soya bean protein and cotton seed protein were efficient inducers. The ability to induce enzyme synthesis was a characteristic property of the individual protein. Enzyme activity was not derepressed in the absence of a protein by limitation of nutrients. Cycloheximide blocked enzyme synthesis. Low levels (1%) of various carbohydrates did not repress enzyme synthesis, whereas most carbohydrates at 3% levels repressed enzyme synthesis. Addition of glucose to cultures actively producing the enzyme blocked further synthesis of enzyme. Addition of glucose to cultures producing the enzyme in the absence of sodium nitrate resulted in a decrease of enzyme activity.

Aspergillus flavus↗
PubMed1990

Effect of a new herbo-mineral hypolipidemic agent on plasma lipoprotein pattern in rat atherosclerosis.

Hyperlipidemia was induced in rats by feeding an atherogenic diet for 5 months. The effect of administration of an indigenous hypolipidemic agent, Anna Kaara Raaja Sindhooram (AKRS) on the plasma lipoprotein profile was studied in the presence and absence of dietary lipid stimuli. Hyperlipidemia produced an enormous increase in the cholesterol and triglyceride contents of the low density (LDL) and very low density (VLDL) lipoprotein fractions and reduced the level of the putative non-atherogenic high density cholesterol (HDL-C). The agarose gel electrophoretic pattern showed a decrease in alpha-lipoproteins and an increase in beta-lipoproteins in the hyperlipidemic rats. AKRS treatment for 5 months altered the lipoprotein pattern favourably by raising HDL-C and lowering LDL-C in the treated rats.

Animals↗
PubMed1990

Molecular characteristics of soluble arthritic collagens.

The molecular characteristics of acid-soluble collagen prepared from animals rendered adjuvant arthritis and matched controls have been thoroughly investigated. The arthritic process was induced in rats by the injection of paraffin oil containing the suspension of heat-killed Mycobacterium tuberculosis at the dorsum of the tail root. In comparison to the normal, the arthritic collagens consistently demonstrated increased solubility of reconstituted fibrils and marked decrease in intrinsic viscosity. Digestion of arthritic collagens with various proteolytic enzymes showed an increased susceptibility over normal collagens. Electrophoresis on SDS-polyacrylamide gels revealed a marked decrease in the concentration of beta-components of arthritic collagens and appreciable increase in the ratio of alpha to beta subunit component. The data clearly indicate that the arthritic collagens are very poor in polymerization due to the impairment of intra and inter-molecular interactions. These changes could explain in part, the altered response of the connective tissues to inflammation and arthritis.

Animals↗
PubMed1989

Studies on the metabolism of glycosaminoglycans under the influence of new herbal anti-inflammatory agents.

The in vivo effect of an herbal based, non-steroidal anti-inflammatory product, salai guggal, prepared from the gum resin exudate of Boswellia serrata and its active principle "boswellic acids" on glycosaminoglycan metabolism has been studied in male albino rats. The biosynthesis of sulfated glycosaminoglycans, as evaluated by the uptake of [35S]sulfate, and the content of glycosaminoglycans were measured in specimens of skin, liver, kidney and spleen. Statistical analysis of the data obtained with respect to the boswellic acids and salai guggal were compared with those of ketoprofen. A significant reduction in glycosaminoglycan biosynthesis was observed in rats treated with all of the drugs. Glycosaminoglycan content was found to be decreased in the ketoprofen-treated group, whereas that of the boswellic acids or salai guggal treated groups remained unaltered. The catabolism of glycosaminoglycans was followed by estimating the activities of lysosomal glycohydrolases, namely beta-glucuronidase, beta-N-acetylglucosaminidase, cathepsin B1, cathepsin B2 and cathepsin D, in tissues and by estimating the urinary excretion and hexosamine and uronic acid. The degradation of glycosaminoglycans was found to be reduced markedly in all drug-treated animals as compared to controls. The potential significance of boswellic acids and salai guggal was discussed in the light of changes in the metabolism of glycosaminoglycans.

Animals↗
PubMed1989

Metabolism of collagen in bone of adjuvant induced arthritic rat.

The metabolism of collagen was examined in bones of rats rendered adjuvant arthritis and matched controls using radioactive isotopic tracer techniques. The rate of the synthesis was studied after the incorporation of tritiated labeled proline into the total bone collagen and determining the content of total hydroxyproline and estimating the specific and total activities of radioactive labeled hydroxyproline. The rate of the catabolism was examined by measuring the activities of various collagen degrading proteolytic enzymes in the bone extract and by estimating the total content of hydroxyproline excreted in the urine. The degradation of collagen was also followed by measuring the specific and total radioactivities of (3H)-hydroxyproline in the urine. When (3H)-proline was injected into the adjuvant arthritic rat, the specific and total radioactivities of (3H)-hydroxyproline in bone collagen were reduced significantly in diseased bone. The activities of various enzymes involved in the catabolism of collagen and other extracellular matrix components were appreciably elevated (about 2-3 fold) in the bone extract of arthritic rat. Similarly, the specific and total activities of (3H)-hydroxyproline in urine samples were also greatly increased in arthritic rats. In addition, the decreased content of hydroxyproline in total bone collagen was accompanied by the increased excretion of urinary hydroxyproline in adjuvant arthritic rats. The results clearly suggest that the arthritic disease induces the qualitative and quantitative changes in bone composition and causes the alteration in the metabolism of collagen in diseased tissue. These observations could therefore, explain in part, the altered response of connective tissue of bone to inflammation and arthritis.

Acetylglucosaminidase↗
PubMed1989

In vitro interaction of bleomycin with collagen--equilibrium dialysis technique.

In an earlier communication, we have presented the results of our study on in vitro interaction of bleomycin with collagens of sepia, fish and rat skins using spectrophotometry. Since the spectrophotometric method does not involve physical separation of the bound and unbound portion of the drug, it was considered worthwhile to test the validity of the use of spectral data by equilibrium dialysis. In the present communication, the values of binding between bleomycin and soluble collagens representing vertebrate, lower vertebrate and invertebrate determined independently at pH 7.4 and 3.0 are presented.

Animals↗
PubMed1989

Separation and evaluation of changing pattern of glycosaminoglycans in 3-methyl cholanthrene induced fibrosarcoma.

The present study evaluates the glycosaminoglycans (GAGs) pattern associated with transplantable rat fibrosarcoma induced by 3-methylcholanthrene. The quantitative analysis of fractionation of GAGs in fibrosarcoma and fetal tissues was performed by enzymatic digestion. The average value of total GAGs in fibrosarcoma and fetal tissue was found to be 4 times higher than its value in the tissue of origin. GAG content showed a steady increase from 7th day onward to 25th day. Hyaluronic acid content in tumor tissue was observed to increase markedly (8-fold) against that of the normal tissue and was equivalent to that of the fetal tissue. Chondroitin sulfate level was also increased in the tumor as well as fetal tissue. The increase in the chondroitin sulfate and hyaluronic acid contents might possibly be due to the abnormal GAG metabolism in the increased production of both sulfated and nonsulfated GAGs.

Animals↗
PubMed1988

Studies on carbohydrate moieties of glycoproteins in established adjuvant induced arthritis.

The investigation presents the metabolic changes in the carbohydrate components of glycoproteins in several tissues of adjuvant arthritic rats. The experimental arthritis induces a significant modification of total carbohydrate moieties of glycoproteins in arthritic tissues. In both acute and chronic phases of the disease, the adjuvant arthritis caused a significant increase in the levels of carbohydrate moieties of tissue glycoproteins viz. total hexose, hexosamine, fucose, sialic acid, total neutral sugar content and neutral sugar monosaccharides. In addition, the urinary excretions of hexosamine and uronic acid in arthritic rats were found to be elevated significantly. The data from the investigation clearly indicate that the experimental arthritis induces an increased glycoprotein synthesis in most of the tissues examined.

Animals↗
PubMed1988

Topical beta-aminopropionitrile and biochemistry of granuloma tissue.

The changes of connective tissue in granuloma development were studied up to 20 days following subcutaneous implantation of polyvinyl alcohol (PVA) sponges in rats. The total protein and collagen content were found to increase from the 4th to 12th days of implantation while the content of DNA continuously decreased with the age of the granuloma. Administration of beta-aminopropionitrile (beta APN) fumarate on the intact skin overlying the implanted PVA sponge in the presence and absence of dimethyl sulfoxide (DMSO) during the growth phase of granuloma development (4th through 12th days after implantation) was accompanied by significant inhibition of collagen polymerization. This was documented by a significant increase of collagen extractable into 1 N NaCl, by a significantly reduced content of aldehydes in collagens extractable into neutral salt solution, and by a significant increase of alpha subunits and alpha/beta ratio. Topical beta APN administration had no effect on the content of DNA, noncollagenous proteins, or total hydroxyproline. We conclude that topically administered beta APN fumarate onto the intact skin penetrates the stratum corneum and effectively inhibits collagen crosslinking in the underlying granuloma tissue. The extent of the effectiveness was found to be significantly greater in the presence of DMSO.

Administration, Cutaneous↗
PubMed1988

Effect of topically applied beta-aminopropionitrile on granuloma tissue biochemistry.

The effects of the percutaneous transport of vehicles and the transport of beta-amino-propionitrile (beta APN) in vehicles were studied in rats. The bioavailability of topically administered beta APN was determined by measuring the degree of collagen cross-linking inhibition in the underlying granuloma tissue. Granulomas were induced by subcutaneous implantation of polyvinylalcohol sponges. From the 4th to 12th days postimplantation, a 20 mg/cm2 dose of beta APN fumarate was applied. Vehicles employed included dimethylsulfoxide (DMSO), urea, and occlusion. DMSO significantly enhanced the effect of beta APN in reducing the cross-linking of collagen. beta APN administered onto urea-pretreated skin and followed by occlusion in the granuloma tissue was more effective than beta APN in 30% DMSO, but only in the parameter reflecting extractibility of collagen into urea or thiocyanate solutions. The results suggest that beta APN administered topically in an appropriate vehicle penetrates the granuloma tissue and affects collagen polymerization. Though beta APN was topically administered, a systemic effect from the drug was evident, as documented by lower body weight of treated rats.

Aminopropionitrile↗
PubMed1987

Physico-chemical studies of micelle formation on sepia cartilage collagen solutions in acetate buffer and its interaction with ionic and nonionic micelles. Hydrodynamic and thermodynamic studies.

Sepia cartilage collagen (pepsin-extracted) in acetate buffer (pH = 2.98) forms micelles at a particular concentration below which they do not normally form. The critical micelle concentration (cmc) of the collagen was determined in buffer as well as in SDS, cetyltrimethylammonium bromide (CTAB) and Tween-80 micellar environments at different temperatures. Mutual interaction of collagen micelles with the ionic and nonionic micelles through the formation of the mixed micelle concept has also been found. The cmc of collagen decreased in the presence of SDS and Tween-80 micelles whereas it increased in the presence of CTAB micelles. This clearly suggests that the micelle formation of collagen is facilitated by the presence of SDS and Tween-80 and hindered by CTAB micelles. The various thermodynamic parameters were estimated from viscosity measurements and the transfer of collagen into the micelles of various surfactants and the reverse phenomenon was analyzed. This analysis has also been modelled conceptually as a different phase and the results have supported the above phenomenon. Our thermodynamic results are also able to predict the exact denaturation temperature as well as the structural order of water in the collagen in various environments. The hydrated volumes, Vh, of collagen in the above environments and intrinsic viscosity were also calculated. The low intrinsic viscosity, [eta], of collagen in an SDS environment compared to buffer and other surfactant environments suggested more workable systems in cosmetic and dermatological skin care preparations. The one and two-hydrogen-bonded models of this collagen in various environments have been analyzed. The calculated thermodynamic parameters varied with the concentration of collagen. The change of thermodynamic parameters from coil-coil to random-coil conformation upon denaturation of collagen were calculated from the amount of proline and hydroxyproline residues and compared with viscometric results. Thermodynamic results suggest that the stability of the collagen in the additive environments is in the following order: SDS greater than Tween-80 greater than buffer greater than CTAB.

Acetates↗
PubMed1987

Urinary excretion of connective tissue metabolites under the influence of a new non-steroidal anti-inflammatory agent in adjuvant induced arthritis.

The therapeutic effect of boswellic acids and salai guggal in adjuvant induced arthritic rats in relation to urinary excretion of connective tissue metabolites viz. hydroxyproline, hexosamine and uronic acid was thoroughly investigated. Compared to controls, the arthritic animals showed an increase in the excretion of these metabolites in urine. The elevated levels of urinary hydroxyproline (free, total, nondialysable and dialysable), hexosamine and uronic acid in the arthritic animals were found to be slightly decreased in the acute phase and significantly decreased in the chronic phase of the disease following the administration of boswellic acids or salai guggal. The results of the investigation indicated that both these anti-inflammatory drugs could offer a partial protective action against changes induced by adjuvant induced arthritis.

Animals↗
PubMed1987

Multiple proteases from Streptomyces moderatus. I. Isolation and purification of five extracellular proteases.

The presence of multiple proteases in the culture filtrate of Streptomyces moderatus was detected. After preliminary purification by ammonium sulfate precipitation and decolorization using DEAE-cellulose, the fractionation of various proteases was carried out using CM-trisacryl cation-exchange chromatography. By this procedure, four different protease fractions (Fr.) were separated (Fr. I, II, III, and IV). The first fraction was further separated into two different proteolytically active fractions (Fr. IA and Fr. Ib) by DEAE-trisacryl anion-exchange chromatography. Fraction Ia was purified further by affinity chromatography on N-carbobenzoxy-D-phenylalanyl triethylenetetramine-Sepharose 4B. The second fraction (Fr. Ib) was purified by gel filtration on Ultrogel AcA 44. For the purification of the other protease fractions (Fr. II, III, and IV) single-step affinity chromatography methods were employed. Protease fractions II and III were purified by epsilon-aminocaproyl-4-(4-aminophenylazo)phenylarsonic acid Sepharose 4B and protease fraction IV was purified on epsilon-aminocaproyl trialanine-Sepharose 4B. All five proteases purified were found to be apparently homogeneous by gel electrophoretic methods.

Chromatography, DEAE-Cellulose↗
PubMed1987

Multiple proteases from Streptomyces moderatus. II. Physicochemical and enzymatic properties of the extracellular proteases.

The physicochemical and enzymatic properties of five different extracellular proteases of Streptomyces moderatus were studied. The first protease was found to be a metal chelator sensitive protease with a Mr of 21,000 +/- 1000 a and a pI of 4.6. The second enzyme was an anionic trypsin-like protease (Mr 19,000 +/- 1000; pI 3.8) with a Km value of 4.76 X 10(-4) M on N-benzoyl-L-arginine-p-nitroanilide. A Km value of 1.52 X 10(-4) M was obtained when N-benzoyl-L-arginine ethyl ester was used as the substrate. The other three enzymes were found to be serine alkaline proteases with Mr's of 22,000, 29,000, and 23,000 +/- 1000 and with respective pI's of 7.8, 8.4, and 9.2. All the proteases showed optimum activity in the alkaline pH range. One of the three proteases was found to possess chymotrypsin and elastase-like properties. All five proteases were found to be unstable at temperatures above 60 degrees C. Except the trypsin-like protease, which was stable only in acidic pH, all other enzymes were found to be stable over a wide range of pH.

Enzyme Stability↗
PubMed1987

Affinity purification of hexosaminidases.

Hexosaminidases A and B were purified by affinity chromatography from normal gastric mucosa, after preliminary separation of isozymes by anion exchange chromatography. Heparin and mannosamine were coupled to Sepharose 4B and used as affinity matrices and the purified enzymes were found to be homogeneous when analysed by polyacrylamide slab gel electrophoresis. This combination of 2 novel affinity chromatographic procedures is superior to existing methods in that a final yield of over 70% could be achieved. Also, the number of steps required to obtain homogeneity are less in contrast to the conventional methods used previously.

Chromatography, Affinity↗