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Biomedical subjects

V L Murty

Publications and source records attributed to V L Murty.

At least 73 records · Page 4Linked to original sources
PubMed1986

Lipid composition and viscosity of parotid saliva in Sjögren syndrome in man.

Extraction of the dialysed and lyophilized saliva of patients with this syndrome by chloroform-methanol yielded 15.9 +/- 2.4 mg of lipid/100 ml of secretion, a level 2-times higher than in normal individuals. The saliva of such patients also had 3-times more glycolipid and 20-times more phospholipid than normal, but differences in the content of neutral lipids were less apparent. The neutral lipids, however, had higher proportions of glycerides, and lower proportions of cholesterol and cholesteryl esters than normal. Viscosity measurements, made with a cone/plate viscometer at shear rates between 1.15 and 230 s-1, revealed similarities between the saliva of normal individuals and Sjögren's syndrome.

Cholesterol↗
PubMed1986

Tooth surface-pellicle lipids and their role in the protection of dental enamel against lactic-acid diffusion in man.

The lipid content and composition of the enamel pellicle from caries-resistant (CR) and caries-susceptible (CS) subjects and their effect on its ability to retard the diffusion of lactic acid were investigated. Lipids accounted for 22.2 per cent of the dry weight of CR pellicle and 23.7 per cent of CS pellicle. The content of glycolipids in both groups was similar but CR pellicle contained 42 per cent less neutral lipids and 31 per cent less phospholipids. CR lipids had a higher content of cholesterol, cholesterol esters and sphingomyelin, whereas CS pellicle was richer in free fatty acids and phosphatidylethanolamine. Retardation of lactic-acid diffusion by CR pellicle was 45 per cent higher than by CS. Removal of lipids caused 50 per cent reduction in retardation by CR pellicle and 35 per cent by CS pellicle.

Adult↗
PubMed1986

Prostaglandin effect on the physical properties of gastric mucus glycoprotein and its susceptibility to pepsin.

The effect of 16,16-dimethyl prostaglandin E2 (DMPGE2) on gastric mucus glycoprotein viscosity, permeability to hydrogen ion and degradation by pepsin was investigated. Preincubation with DMPGE2 produced a marked enhancement in the glycoprotein viscosity. The increase was concentration dependent and at 2.6 X 10(-5)M DMPGE2 reached a value of 178%. Permeability measurements revealed that 2.6 X 10(-7)M DMPGE2 increased the retardation ability of the glycoprotein to hydrogen ion by 10%, while 22% increase was obtained with 2.6 X 10(-4)M DMPGE2. The results of peptic activity assay showed that DMPGE2 had no inhibitory effect on the rate of glycoprotein proteolysis, and actually a small stimulatory influence was consistently observed. The results suggest that prostaglandins beneficially affect the physical properties of mucus glycoprotein which are considered to be essential for the protective function of gastric mucus.

16,16-Dimethylprostaglandin E2↗
PubMed1986

Effect of covalently bound fatty acids and associated lipids on the viscosity of gastric mucus glycoprotein in cystic fibrosis.

The contribution of associated and covalently bound lipids to the viscosity of gastric mucus glycoprotein in healthy and cystic fibrosis (CF) individuals was investigated. While both preparations exhibited similar contents of protein and carbohydrate, the CF glycoprotein contained 1.3 times more associated lipids and 6 times more covalently bound fatty acids. The viscosity of CF mucus glycoprotein was about 1.8 times higher than that of normal glycoprotein. Extraction of associated lipids lead to 3-fold drop in the viscosity of CF glycoprotein and 5-fold drop in the case of normal glycoprotein. Removal of covalently bound fatty acids caused further 1.6-fold reduction in the viscosity of normal mucus glycoprotein and 6-fold in CF glycoprotein. The viscosity of the delipidated and deacylated CF mucus glycoprotein was only about 10% higher than that of the similarly treated normal glycoprotein. The results suggest that the elevated level of covalently bound and associated lipids is responsible for the increased viscosity of CF mucin.

Adolescent↗
PubMed1985

Fatty acid acylation of salivary mucin in rat submandibular glands.

The acylation of salivary mucin with fatty acids and its biosynthesis was investigated by incubating rat submandibular salivary gland cells with [3H]palmitic acid and [3H]proline. The elaborated extracellular and intracellular mucus glycoproteins following delipidation, Bio-Gel P-100 chromatography, and CsCl equilibrium density gradient centrifugation were analyzed for the distribution of the labeled tracers. Both preparations gave single bands at the CsCl density of 1.48, in which carbohydrate peaks coincided with that of the labels. The [3H]palmitic acid in these glycoproteins was susceptible to cleavage by alkali and hydroxylamine, thus indicating the ester nature of the bond. With both intracellular and extracellular glycoproteins deacylation caused the glycoproteins to band in the CsCl gradient at a density of 1.55. The incorporation of both markers into mucus glycoprotein increased steadily with time up to 4 h, at which time about 65% of [3H]palmitate and [3H]proline were found in the extracellular glycoprotein and 35% in the intracellular glycoprotein. The incorporation ratio of proline/palmitate, while showing an increase with incubation time in the extracellular glycoprotein, remained essentially unchanged with time in the intracellular glycoprotein and at 4 h reached respective values of 0.14 and 1.12. The fact that the proline/palmitate incorporation ratio in the intracellular glycoprotein at 1 h of incubation was 22 times higher than in the extracellular and 8 times higher after 4 h suggests that acylation occurs intracellularly and that fatty acids are added after apomucin polypeptide synthesis. As the incorporation of palmitate within the intracellular mucin was greater in the mucus glycoprotein subunit, it would appear that fatty acid acylation of mucin subunits preceeds their assembly into the mucus glycoprotein polymer.

Acylation↗
PubMed1985

Lipids of developing dental plaque in caries-resistant and caries-susceptible adult people.

Dental plaque maturation in both caries-resistant (CR) and caries-susceptible (CS) subjects was accompanied by a decrease in total lipid content but was more pronounced with CR subjects; their plaque after 72 h contained 44.6 per cent less lipids than that of CS. At each stage of maturation, differences were also found in the proportion of lipid classes. In 24 h-plaque, the lipids of CR-group, although containing amounts of glycolipids and phospholipids similar to those of CS, contained 1.6 times less neutral lipids. The 48 h-plaque of CS subjects showed 2.5 times more neutral lipids, 1.2 times more phospholipids and 1.4 times less glycolipids. The 72 h-CR plaque contained 1.9 times less neutral lipids, 1.6 times more glycolipids and 1.3 times more phospholipids than CS-plaque. Among the neutral lipids in both groups, the changes with maturation were associated with decrease in free fatty acids and increase in triglycerides, cholesterol and cholesteryl esters. Phospholipids of CR-plaque contained less phosphatidylcholine and more phosphatidylethanolamine than CS-plaque. With plaque maturation both groups showed decreases in the glycolipids characteristic of saliva and an increase in the content of bacterial type of glycolipids. Plaque maturation is evidently accompanied by dynamic changes in lipids reflecting a shift from salivary to bacterial contribution.

Adult↗
PubMed1985

Lipid composition of squirrel monkey (Saimiri sciureus) saliva.

The content and composition of lipids in saliva of healthy caries-free squirrel monkeys were investigated. The dialyzed and lyophilized saliva on extraction with chloroform/methanol yielded 8.0 +/- 0.9 mg of lipids/100 ml of saliva. Following fractionation on silicic acid column, 30.9% of lipids were found in the neutral lipid fraction, 58.8% in the glycolipid fraction, and 10.3% in the phospholipid fraction. The neutral lipids exhibited high content of free fatty acids (58.8%) and triglycerides (23.3%), the glycolipids consisted mainly of neutral and sulfated glyceroglucolipids (95%), while the phospholipids were rich in sphingomyelin and phosphatidylcholine. The results show that squirrel monkey saliva, while displaying lipid content similar to that of caries-susceptible humans, contains 50% less lipids than saliva of periodontal disease-prone marmoset.

Animals↗
PubMed1985

Effect of sucralfate on the viscosity and retardation of hydrogen ion diffusion by gastric mucus glycoprotein.

The effect of an antiulcer drug (sucralfate) on the viscosity and the ability of pig gastric mucus glycoprotein to retard the diffusion of hydrogen ions was investigated. Preincubation with sucralfate produced a marked enhancement in the glycoprotein viscosity. This enhancement was concentration-dependent and at 1.0 X 10(-3) M sucralfate a 60% increase in viscosity was attained. Permeability measurements revealed that sucralfate caused a substantial improvement in the ability of the glycoprotein to retard the diffusion of hydrogen ions. At 1.0 X 10(-3) M sucralfate, permeability decreased by 25% and a 43% reduction was obtained with 1.0 X 10(-3) M sucralfate. It is suggested that sucralfate, by increasing the viscosity of the glycoprotein and by improving its ability to retard the diffusion of hydrogen ions, strengthens the integrity of gastric mucus.

Aluminum↗
PubMed1985

Effect of ethanol on the peptic degradation of gastric mucus glycoprotein.

The effect of ethanol on the proteolytic activity of pepsin towards gastric mucus glycoprotein was investigated. Undegraded mucus glycoprotein isolated from pig stomach was incubated with pepsin in the presence and absence of ethanol, and the released alpha-amino residues were quantitated by the trinitrophenylation procedure. In the absence of ethanol the rate of proteolysis was proportional to mucus glycoprotein concentration up to 450 micrograms and remained constant with time of incubation for at least 30 min. The apparent Km value of pepsin for pig gastric mucus glycoprotein was 8.7 X 10(-7)M. The proteolytic activity of pepsin towards mucus glycoprotein was inhibited by ethanol. The rate of inhibition was proportional to the ethanol concentration up to 0.8 M and was of competitive type. The apparent K1 value calculated from the double-reciprocal plots for ethanol was 2.2 X 10(-6)M. The inhibitory effect of ethanol on the proteolysis of gastric mucus glycoprotein may be of physiological significance.

Animals↗
PubMed1984

Lipid composition of the secretion from human bronchial explant culture.

In this study, we identified and quantitated the lipid components in the secretions of human bronchial explants cultured in a serum-free medium over a period of 50 days. Total lipids represented 6% of the dry material. This amount is considerably lower than that reported for 'normal' human sputum and suggests that the latter is contaminated by serum transudates, alveolar secretions, and microorganisms. Such serum-free culture systems are highly suitable to study cell physiology as it relates to human disease.

Bronchi↗
PubMed1984

Effect of lipids and proteins on the viscosity of gastric mucus glycoprotein.

The effect of associated lipids and covalently bound fatty acids, and the contribution of serum albumin and secretory IgA to the viscosity of dog gastric mucus glycoprotein was investigated. Using a cone/plate viscometer at shear rates between 1.15 - 230s -1, it was found that extraction of associated lipids from the glycoprotein lead to 80-85% decrease in the viscosity. Further loss (39%) in viscosity of the delipidated glycoprotein occurred following removal of covalently bound fatty acids. Reassociation of the delipidated glycoprotein with its neutral lipids increased the viscosity 3-fold, a 2.5-fold increase was obtained with glycolipids, and 2-fold with phospholipids. Preincubation of purified mucus glycoprotein with albumin or IgA resulted in the increase in viscosity. This increase in viscosity was proportional to albumin concentration up to 10%, and to IgA concentration up to 5%. The results show that interaction of lipids and proteins with mucus glycoprotein contributes significantly to the viscosity of gastric mucus.

Animals↗
PubMed1984

Effect of ethanol on the enzymatic sulfation of glycosphingolipids in gastric mucosa.

The enzyme activity which catalyzes the transfer of sulfate group from 3'-phosphoadenosine 5'-phosphosulfate to C-3 of the galactose residue of galactosylceramide and lactosylceramide has been demonstrated in the Triton X-100 extracts of the microsomal fraction of rat gastric mucosa. The sulfotransferase activity of this fraction in antral mucosa was 1.2-1.3 times greater than that of the body and 19-22 times greater than that of the forestomach. The enzyme did not catalyze the transfer of sulfate to glucosylceramide, trihexosylceramide, and triglucosyl monoalkylmonoacylglycerol. Optimum enzymatic activity was obtained using 0.4% Triton X-100, 33 mM NaF, and 15 mM MgCl2 at a pH of 6.8. The sulfotransferase activity was inhibited by ethanol. With both glycolipid substrates, little inhibition of enzyme activity was obtained up to 0.5 M ethanol. However, higher concentrations of ethanol produced severe inhibitory effect. This inhibition of sulfation of galactosylceramide and lactosylceramide by ethanol was of the competitive type. The apparent KI values were 8.3 X 10(-5) for galactosylceramide and 5.6 X 10(-5) for lactosylceramide.

Animals↗
PubMed1984

Lipid composition of marmoset saliva.

The lipid content and composition of marmoset saliva was investigated. Extraction of the dialyzed and lyophilized saliva with chloroform/methanol yielded 15.6 +/- 3.1 mg of lipids/100 ml of saliva. Of the total lipids, 41.7% were represented by neutral lipids, 50.7% by glycolipids and 7.6% by phospholipids. Neutral lipids had a high content of free fatty acids (67.0%), cholesterol and its esters (20.0%) and triglycerides (11.8%). The glycolipid fraction was comprised of simple glycosphingolipids (13.2%), and of neutral and sulfated glyceroglucolipids (86.8%), whereas sphingomyelin, phosphatidylcholine and phosphatidylethanolamine accounted for 63.6% of the total phospholipids. The results indicate that marmoset saliva, in comparison to that of human, contains twice as much of total lipids and exhibits an elevated level of phospholipids, and glycolipids.

Animals↗
PubMed1983

Lipids associated with rat small-intestinal mucus glycoprotein.

The lipid content and composition of rat small-intestinal mucus, and the purified mucus glycoprotein before and after Pronase digestion were investigated. The mucus, obtained by the instillation of intestine with 2M NaCl, was fractionated on Bio-Gel A-50 in the presence of 6M urea and the mucus glycoprotein free of noncovalently bound protein was isolated. A portion of the purified glycoprotein was subjected to Pronase digestion to yield glycopeptides. The native mucus, and the purified glycoprotein and glycopeptides were extracted with chloroform-methanol, and the lipids contained in the extracts were analyzed. The lipids accounted for 17.6 of the dry weight of mucus, 26.4 of the mucus glycoprotein, and 25.3% of the glycopeptides. In comparison to mucus, the lipids associated with mucus glycoprotein contained 1.9 times more phospholipids and 2.1 times more glycolipids, showed a 26% increase in neutral lipids, and were virtually free of glycosphingolipids. Treatment of the purified glycoprotein with Pronase led to a moderate (22.3%) loss in neutral lipids, 4.3-fold decrease in phospholipids, and 52.3% increase in glyceroglucolipids. The results indicate that while the interaction of mucus glycoprotein with phospholipids involves its Pronase-susceptible region, the interaction with glyceroglucolipids occurs in the glycosylated region of the glycoprotein that is resistant to proteolysis.

Animals↗
PubMed1983

Enzymatic sulfation of triglucosyl monoalkylmonoacylglycerol in rat salivary glands.

A sulfotransferase activity present in the cytosol fraction of rat submandibular and parotid salivary glands catalyzes the transfer of sulfate group from 3'-phosphoadenosine-5'-phosphosulfate to C-6 of the terminal glucose residue of Glc alpha 1 leads to 6Glc alpha 1 leads to 6Glc alpha 1 leads to 3-1, (3)-0-alkyl-2-0-acylglycerol to form sulfated triglucosyl glyceroglucolipid. The reaction proceeds at its optimum at pH 7.8, and requires the detergent Triton X-100, F1- and Mg2+. The enzyme does not catalyze the sulfation of glycosphingolipids. The apparent Km of the submandibular enzyme for triglucosyl glyceroglucolipid is 78.4 microM, and that of parotid, 58.8 microM. Analysis of the permethylated 35S-labeled enzymatic product demonstrated that the sulfate group is located at C-6 of the terminal glucose residue.

Animals↗
PubMed1983

Lipid composition of human labial salivary gland secretions.

Extraction of the dialysed and lyophilized labial saliva with chloroform/methanol yielded 423.8 +/- 73.0 micrograms of lipids/ml of saliva, a level 4-5 times higher than in the major salivary glands. Of the total lipids, 32.4 per cent were represented by neutral lipids, 44.6 per cent by glycolipids and 23.0 per cent by phospholipids. Neutral lipids had a high content of free fatty acids (43.8 per cent), cholesteryl esters (26.9 per cent) and triglycerides (15.4 per cent). The glycolipids consisted mainly of neutral (74.6 per cent) and sulphated (25.4 per cent) glyceroglucolipids, whereas phosphatidylethanolamine, phosphatidylcholine, sphingomyelin and phosphatidylserine accounted for 54.7 per cent of the total phospholipids.

Adult↗
PubMed1983

Association of lipids with proteins and glycoproteins in human saliva.

The distribution of lipids in the fractions of parotid and submandibular saliva following Bio-Gel A-50 column chromatography was measured. Over 50% of the total lipids of submandibular saliva was found in the fraction which contained mainly the high-molecular-weight glycoprotein. This fraction also contained most of the glycolipids, free fatty acids, phospholipids, and cholesterol. In the parotid saliva, the fraction containing the basic glycoprotein (the major glycoprotein fraction of parotid saliva) contained 35% of the total saliva lipids and was enriched in phospholipids ana cholesterol esters.

Adult↗