Biomedical subjects
Publications and source records attributed to A Slomiany.
Three new fucolioids have been isolated from the water-soluble glycolipid fraction of hog gastric mucosa. Fucolipid A and C exhibited blood-group-A activity, whereas Fucolipid B was not active in A-anti-A, B-anti-B and H-anti-H systems. The structures of these glycolipids were identified by partial acid hydrolysis and methylation analysis, as: (see article)
A new difucosyl glycolipid exhibiting blood group A activity was isolated from water-soluble glycolipid fraction of hog gastric mucosa. The structure of this glycolipid was identified by partial acid hydrolysis, sequential degradation with specific glycosidases and methylation analysis, as: "see article".
Gastric mucosal lipid patterns were studied in normal and in restrained rats which developed mucosal erosions. Organic solvent extraction, silicic acid column, and thin-layer chromatography were employed to separate and gas-liquid chromatography and spectrophotometry to quantitize the individual lipid components. Chemical analysis revealed profound alterations in the mucosal lipid profiles of rats with gastric mucosal erosions. Cholesterol esters were markedly elevated, cholesterol, free fatty acids and phosphatidylethanolamine were markedly lower in the extracts of ulcerated tissue, and the titer of lysophospholipids was about eight times higher than in the controls. Lipid phosphorus was elevated in stressed rats. The amount of neutral glycolipids was similar for both groups, but tetra- and oligohexoside ceramides, which were present in the gastric mucosa of the control rats, were virtually absent from the ulcerated mucosa. In contrast to the alterations in lipid profile mentioned above, the total lipid weight per tissue preparation was very similar for the ulcerated and normal control groups.
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The present study investigated the effect of acute ethanol (ETOH) treatment on the epidermal growth factor (EGF) receptor in rat gastric mucosa using two different experimental models. In the in vitro experiments, gastric mucosal cells were incubated with 0, 0.05, 0.1, 0.25, and 0.5% ethanol in Dulbecco's modified Eagle's medium (DMEM) for 30 min and then used for the membrane preparation. The EGF receptor binding assay indicated that cells incubated in the presence of ethanol displayed a concentration-dependent increase (r = 0.85) in the 125I-EGF binding. The Western blot analysis using anti-EGF-receptor antibody revealed that ethanol in vitro caused reduction in the immunoreactivity of the major 170-kDa protein. There were also alterations in the minor protein bands (140, 120, and 50 kDa). In the in vivo experiments, rats that fasted overnight were given 1.0 ml of saline or ethanol (5, 10, or 15%) by gastric intubation 30 min before sacrifice. In comparison with the saline controls, ethanol treatment caused a decrease of the EGF receptor binding to the gastric mucosal membrane (saline: 5%: 10%; 15% ETOH, 1.46 +/- 0.18: 1.13 +/- 0.17: 1.27 +/- 0.19: 0.84 +/- 0.14, p < 0.02; mean +/- SEM, n = 9). Furthermore, the immunoblot analysis revealed concentration-dependent decrease in the intensity of the major 170-kDa protein with ethanol. The reduction in the EGF receptor binding and the impairment of the receptor protein might be due to the nonspecific damage of the gastric mucosal membrane by ethanol.
Mucus glycoprotein (mucin) is the principal biochemical constituent of sputum. Appreciable quantities of lipid, DNA, and nonmucin proteins are also present, particularly in purulent sputum. Previous studies have shown that purified mucin from respiratory tract secretions contains non-covalently bound lipid. However, it is not known whether lipids in purulent sputum are associated only with mucin or with nonmucin proteins and DNA as well. Purulent sputum was obtained from cystic fibrosis patients. Tracheal aspirates were obtained from noncystic patients with purulent secretions due to Pseudomonas species, as well as from noninfected, noncystic patients who had mucoid airway secretions. The lipid content of unfractionated airway secretions (sputum or tracheal aspirates), gel filtration-purified mucin, and nonmucin components of the airway secretions was analyzed. The purified mucin from all three groups had a significantly higher content of solvent-extractable lipid as compared to unfractionated airway secretions. The nonmucin fractions contained only small amounts of lipid. Density gradient centrifugation verified that the lipid recovered in the purified mucin fraction was complexed with the glycoprotein. The results of this study indicate that most of the lipids in purulent sputum are associated with mucin.
The effect of bile acids on the glycoprotein constituent of gastric mucus was investigated. Ghosh-Lai rat stomachs were instilled in vivo for 1 h with buffered saline (control) followed by various bile acids in saline at pH 2.0-7.0. Following quantitative recovery, the instillates were used for the isolation of mucus glycoprotein. The results of analyses revealed that while taurocholic acid exerted essentially identical depletory effects throughout the entire pH range tested, the cholic acid had little depletory effect on the mucus below pH 5.0, and glycocholic acid below pH 4.0. The extent of mucus glycoprotein depletion by bile acids under optimal pH conditions was clearly dependent upon the bile acid concentration as well as its type. The maximum depletory effect with the lowest concentration of bile acid was achieved with taurocholate followed by glycocholate and cholate. Comparison of the depletory effects of mono-, di-, and trihydroxy conjugated and unconjugated bile acids revealed that, within each group, the highest degree of mucus glycoprotein depletion occurred with taurine conjugates. The number of hydroxyl groups on the bile acid molecule appears to exert a less evident effect on the depletory capacity. The results suggest that the in vivo depletion of gastric mucus of its glycoprotein constituent by bile acids depends on the pH of luminal exposure and on the bile acid composition.
The lipid content and composition of dog gastric mucus and its mucus glycoprotein before and after Pronase digestion was investigated. The mucus and the purified glycoprotein, in its intact and degraded form, were extracted with chloroform/methanol and the lipids contained in the extracts were quantitated. The lipids accounted for 18.9% of the dry weight of mucus and their content increased to 29.4% in the purified glycoprotein and fell to 27.8% following digestion of the glycoprotein with Pronase. In comparison to mucus, lipids associated with undegraded glycoprotein contained 1.7 times more phospholipids and 1.8 times more glycolipids, and were virtually free of glycosphinoglipids. Pronase digestion of the glycoprotein led to 2.3-fold decrease in phospholipids and 1.3-fold increase in glyceroglucolipids. The results suggest that the interaction of mucus glycoprotein with phospholipids involves its nonglycosylated region.
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