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Biomedical subjects

Y N Lin

Publications and source records attributed to Y N Lin.

At least 55 records · Page 3Linked to original sources
PubMed1982

Cerebroside sulfotransferase in rat gastric mucosa.

1. Cerebroside sulfotransferase activity was demonstrated in rat gastric mucosa. This enzyme preparation catalyzes the transfer of sulfate group from 3'-phosphoadenosine-5'-phosphosulfate to added cerebroside and lactosylceramide. 2. Psychosine also serves as an acceptor for sulfate group. 3. Both hydroxy-fatty acid and non-hydroxy-fatty acid containing cerebrosides are equally sulfated. However, this enzyme is inactive toward glucosylceramide. 4. The optimum pH is around 6.0. The reaction is stimulated by the addition of 0.4-0.9% of Triton X-100. 5. The presence of 2-4 mM ATP moderately stimulates the reaction, but is inhibitory when the concentration exceeds 6 mM. 6. EDTA has no effect. 7. Both Mg2+ and Ca2+ stimulate at lower concentrations (less than 16 mM), but inhibit at higher concentrations (greater than 20 mM). Mn2+, however, is a strong inhibitor even at 8 mM concentration. 8. The apparent Km for cerebroside is 0.04 mM, while that for 3'-phosphoadenosine-5'-phosphosulfate is 0.45 microM.

Animals↗
PubMed1980

Enzymatic sulfation of cholesterol by rat gastric mucosa.

A sulfotransferase which catalyzes transfer of the sulfate group from 3'-phosphoadenosine-5'phosphosulfate to cholesterol has been demonstrated in the rat gastric mucosa. The product of the reaction was characterized as cholesterol sulfate by two-dimensional thin-layer chromatographic behavior, and gas-liquid chromatography of cholesterol after acid solvolysis. The bulk of enzyme activity was found in the cytosol fraction. Sulfation of cholesterol did not require added Mg+2, Mn+2, or Ca+2, and was unaffected by ethylenediaminetetraacetate. Triton X-100 moderately enhanced the enzyme activity. A broad pH optimum from pH 6.0-9.0 was exhibited with a maximum at pH 7.0-7.5. The apparent Km for PAPS was 0.8 x 10(-6)M. The possible function of cholesterol sulfate in gastric mucosa is discussed.

Animals↗
PubMed1980

Report of a case of Nezelof syndrome.

In this report, we present a 5 months old male baby, who suffered from watery diarrhea since 4 days old. From then on, he had been admitted 3 times in 3 different hospitals but the symptoms still bothered him off and on. During the days of hospitalization, sepsis with positive blood culture of Klebsiella was noted. The patient expired at 5 months of age. The T cell count was 20% active T was 0. Delayed hypersensitivity skin tests including Candida (10 X), PHA (10 micrograms), PHA (1 microgram), SK/SD (50 units) were negative. The granulocyte function study showed normal. Immunoglobulin analysis revealed IgG: 1320 mg%, IgA: 120 mg%, IgM: 100 mg%. Agenesis of thymus, failure of lymphoid differentiation and abnormal lymphoid architecture with absence of germinal centers were noted at autopsy. Combined immunodeficiency with normal immunoglobulins (Nezelof syndrome) is a disease of primary immunodeficiency characterized by recurrent infections, failure to thrive, lymphopenia, diminished lymphoid tissue, abnormal structure or agenesis of the thymus, and presence of normal or increased levels of one or more of the major immunoglobulin classes, but with impaired antibody synthesis. Since its original description by Nezelof and associates in 1964, it has been reported on the subsequent occasion. In this report, we present our one experience and review the clinical and laboratory data in 33 reported cases.

Humans↗
PubMed1979

Molecular species of phosphatidylcholine from rat gastric mucosa.

Phosphatidylcholine of rat gastric mucosa were found to constitute about half of the total phospholipids. The composition of 20 molecular species accounting for approx. 90% of the total phosphatidylcholine was determined by specific enzymic hydrolyses and AgNO3 thin-layer and gas-liquid chromatography. Disaturated (dipalmitoyl) phosphatidylcholine made up about 31% of the total phosphatidylcholines. Other species which occurred in significant concentrations included 16:0/18:1, 18:0/18:1, 16:0/18:2, 18:0/18:2, 16:0/18:3, 18:0/18:3, 16:0/20:4, and 18:0/20:4. These results indicate that rat gastric mucosa is similar to lung in that both contain elevated amounts of dipalmitoyl phosphatidylcholine. Other similarities between these two tissues are discussed.

Animals↗
PubMed1978

Phospholipid-deacylating enzymes of rat stomach mucosa.

1. Rat stomach mucosa exhibited three distinguishable phospholipid-deacylating enzyme activities: lysophospholipase, phospholipase A1 and phospholipase A2. 2. The lysophospholipase hydrolyzed 1-palmitoyl lysophosphatidylcholine to free fatty acid and glycerophosphorylcholine. This enzyme had an optimum pH of 8.0, was heat labile, did not require Ca2+ for maximum activity and was not inhibited by bile salts or buffers of high ionic strength. 3. Phospholipase A2 and phospholipase A1 deacylated dipalmitoyl phophatidylcholine to the corresponding lyso compound and free fatty acid. The specific activity of phospholipase A2 was 2--4-fold higher than that of phospholipase A1 under all the conditions tested. Both activities were enhanced 4--7.5-fold in the presence of bile salts at alkaline pH and 11-18-fold at acidic pH. 4. In the absence of bile salts, phospholipase A1 exhibited pH optima at 6.5 and 9.5 and phospholipase A2 at pH 6.5, 8.0 and 9.5. The pH optima for phospholipase A1 were shifted to pH 3.0, 6.0 and 9.0 in presence of sodium taurocholate; the activity was detected only at a single pH of 9.5 in the presence of sodium deoxycholate and at pH 10.0 in the presence of sodium glycocholate. Phospholipase A2 optimum activity was displayed at pH 3.0, 6.0 and 8.0 in presence of taurocholage, pH 7.5 and 9.0, in presence of glycocholate and only at pH 9.0 in presence of deoxycholate. 5. Ca2+ was essential for optimum activity of phospholipases A1 and A2. But phospholipase A1 lost complete activity in presence of 0.5 mM ethyleneglycolbis-(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) at pH 6.0, whereas phospholipase A2 lost only 50%. 6. Phospholipases A1 and A2 retained about 50% of their activities by heating at 75 degrees for 10 min. At 100 degrees, phospholipase A1 retained 22% of its activity, whereas phospholipase A2 retained only 7%.

Animals↗
PubMed1977

Effect of propylthiouracil on intestinal tumor formation by azoxymethane in rats.

Treatment with propylthiouracil (PTU) resulted in a significant decrease in azoxymethane-induced intestinal tumors, total concentration of fecal bile acids as well as the fecal neutral steroids, cholesterol and coprostanol. Thus, a hypothyroid state induced by PTU treatment may affect intestinal carcinogenesis in this animal model by lowering the concentration of fecal bile acids and neutral steroids.

Adenocarcinoma↗
PubMed1976

Effect of diet high in beef fat on the composition of fecal bile acids during intestinal carcinogenesis in the rat.

Two groups of 20 male Sprague-Dawley rats each were given sc 8 mg azoxymethane/kg body weight and fed a normal diet or one high in beef fat. Control groups were not given azoxymethane. Fat-control animals did not excrete more total bile acids than did the normal-control group but did excrete more deoxycholic acid as the result of increased cholic acid degradation. Azoxymethane itself caused an increase in fecal bile acid concentratation but tended to reduce the level of cholic acid degradation. Fatty acid content in the feces increased in the animals on the fat diet but was not affected by azoxymethane. A fat-diet-dependent increase was apparent in total fecal neutral steroids and a carcinogen-dependent increase in cholesterol degradation. Dietary fat and bile steroids altered by gut microflora were important interrelated factors in the intestinal carcinogenic process of this animal model.

Animals↗
PubMed1973

Sexual differences in galactose metabolism: galactosyl ceramide galactosidase and other galactosidases in mouse kidney.

Male and female mice were compared at two ages, 15 and 50 days, with respect to the activities of three galactosidases in kidney. No sex difference in enzyme activity was seen in the young mice, but appreciable differences were found in the older animals. The male kidneys had about one-third higher specific activities of cerebroside beta-galactosidase and nitrophenyl beta-galactosidase, but there was no difference with nitrophenyl alpha-galactosidase. A listing and discussion of other galactose-metabolizing enzymes influenced by sex differences is presented.

Age Factors↗