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Biomedical subjects

Y S Shin

Publications and source records attributed to Y S Shin.

At least 145 records · Page 8Linked to original sources
PubMed1984

Glycosylated haemoglobin and glycosylated albumin: evaluation of different methods in diabetic control.

The levels of glycosylated haemoglobins and albumin were determined in 56 diabetic patients aged between 5 and 19 years. The glycohaemoglobin levels were measured by two different methods, cation-exchange chromatography and a colorimetric chemical method. The glycosylated albumin levels were measured by a chemical method in plasma albumin purified with Affi-gel Blue. The results were compared with other indicators such as blood glucose and urinary glucose. The postprandial blood glucose levels were well correlated with the levels of glycoproteins: glycohaemoglobin by the column method (r = 0.886), glycohaemoglobin by the chemical method (r = 0.72) and glycoalbumin (r = 0.662). The urinary levels of glucose showed a weak correlation with blood glucose levels (r = 0.214) and with glycoalbumin (r = 0.298), but no correlation with glycohaemoglobin. Significant correlations between the changes of glycosylated albumin levels and glycohaemoglobin were found (r = 0.78). The result of the comparison of the chemical method with the column method for glycohaemoglobin determination showed a high correlation between the values (r = 0.95). There were significant differences in glycosylated protein levels between normal and diabetics. There were also significant differences in glycohaemoglobin and glycoalbumin values between fairly managed and poorly managed groups of diabetics. Of the three parameters, glycoalbumin, glycohaemoglobin and plasma glucose, the greatest absolute changes were found in the levels of glycoalbumin.

Adolescent↗
PubMed1983

Prenatal diagnosis of galactosemia and properties of galactose-1-phosphate uridyltransferase in erythrocytes of galactosemic variants as well as in human fetal and adult organs.

The kinetic characteristics and isoelectrofocusing patterns of uridyltransferase and the concentrations of galactose-1-phosphate in hemolysates were investigated in a family with compound variants of Duarte and classical galactosemia. There were no significant differences in Km values between the genotypes. However, the isoelectrofocusing study with thin-layer polyacrylamide gels (PAGIF) as well as with agarose gels (AGIF) showed a distinctive difference. The enzyme from the Duarte variant resolved into at least two more activity bands at pH between 5.2 and 5.4. The accumulation of galactose-1-phosphate was observed only in homozygotes for classical galactosemia. Compound heterozygotes (G-D) without any clinical manifestations did not show an accumulation of galactose-1-phosphate. The isoelectrofocusing study of the enzyme in human tissues revealed their activity resolving into multiple bands, 6-8 bands at pH 5.50-6.00 and 1-3 bands at pH 4.9-5.2. No significant differences were found in the patterns between fetal and adult liver except that the intensity of the anodic bands (pH 4.9-5.2) was weaker in fetal tissues. Prenatal diagnosis of classical galactosemia was performed in nine families by measuring the enzyme activity in cultivated amniotic fluid cells. Absence of the enzyme activity in amniotic fluid cells was found in two cases, and in four cases the heterozygosity was diagnosed by a relative low enzyme activity, 30-50% of the activity in control cells cultured in parallel.

Amniotic Fluid↗
PubMed1983

A radioisotopic method for fructose-1-phosphate aldolase assay that facilitates diagnosis of hereditary fructose intolerance.

A sensitive new method in which D-[U-14C]fructose-1-phosphate is used for fructose-bisphosphate aldolase (EC 2.1.2.13) assay is described. The radioactive fructose-1-phosphate compound was prepared from [U-14C]fructose by use of partly purified fructokinase (EC 2.7.1.4). With this method we measured normal values for aldolase in human liver (2.4-10.0 nmol/min per mg of protein), kidney (3.6-3.8), and intestine (4.2-10.0) as well as Km values for fructose-1-phosphate (approximately 1.0-2.2 mmol/L). In patients with hereditary fructose intolerance the aldolase activity in liver and intestine was less than 10% of normal values. The Lineweaver-Burk plots for data from patients with hereditary fructose intolerance were hyperbolic, indicating a structural alteration in the enzyme.

Adult↗
PubMed1982

Parenteral nutrition with a "breast milk adapted" solution of amino acids in infants and children after abdominal surgery.

Plasma amino acid levels as well as urinary and plasma concentrations of nitrogen were determined in 24 infants and 12 children on five consecutive days after major abdominal surgery. Parenteral nutrition was carried out by means of two different amino acid solutions. One formula (PE) was based on the amino acid composition of potato-egg protein, the other (BM) on that of human breast milk. Control subjects received glucose only. The controls showed decreased plasma levels of most amino acids as well as negative nitrogen balances. In contrast, in the patients treated with amino acids the plasma concentrations of most amino acids were found in the normal range. In the infants elevated plasma amino acid levels were found more often in the BM-group than in the PE-group. Among the children, however, the PE-group showed an elevation in the plasma levels of amino acids more frequently than the BM-group. There is no significant difference in the positive nitrogen balance between the BM-groups and the PE-groups. Therefore, it can be concluded that the use of BM has no clear advantage over that of PE.

Abdomen↗
PubMed1977

The influence of folate antagonists on the metabolism of folic acid and its reduced derivatives in rat liver and kidney.

Uptake and conversion of [3H]folic acid to polyglutamate derivatives by rat liver and kidney were inhibited by methotrexate or aminopterin (15 mg/kg body weight) and DL-tetrahydromethotrexate (30 mg/kg body weight). In contrast, these antagonists did not influence the conversion of L-5-formyl-[3H]tetrahydrofolic acid or L-5-methyl[3H]tetrahydrofolic acid to polyglutamine derivatives and had little effect on the uptake of reduced folate derivatives. When [3H]methotrexate, [3H]aminopterin, and DL-[3H]tetrahydromethotrexate were administered in small amounts (15 mug/kg body wieght), no metabolites of these compounds were observed. However, at higher doses of [3H]methotrexate (300 mug/kg body weight), more than 30% of the radioactivity remaining in the tissue 24 hr after administration could be attributed to a metabolite of methotrexate. This metabolite was tentatively identified as methotrexate diglutamate.

Aminopterin↗
PubMed1976

Subcellular localization of gamma-glutamyl carboxypeptidase and of folates.

The subcellular distributions of glutamyl carboxypeptidase, folate specific activities, and radioactive metabolites of injected [3H] folic acid were studied in rat liver. The specific activity of glutamyl carboxypeptidase in the lysosomal fraction was near or greater than four times that in the other subcellular fractions. The specific activity of folates was highest in the soluble fraction (102 ng folate/mg protein) and lowest in the microsomal fraction (22 ng folate/mg protein). Nuclear, mitochondrial, and lysosomal folates were 95% folate polyglutamates, and microsomal and soluble folates were 85--90% folate polyglutamates. Injected [3H] folic acid was initially concentrated in the microsomal fraction, as measured by 3h cpm per ng folate. Initially, injected [3H] folic acid was found converted to folate penta- and hexaglutamates in all fractions to a similar extent except in the microsomes where the percentage conversion was much less, as measured by the percentage of total 3H cpm determined to be [3H] folate penta- and hexaglutamates. At 24 h, the conversion of [3H] folates to penta- and hexaglutamates in each fraction was less than that found for the endogenous folates. Injected [3H] folic acid after 2h was found to consist of 94% reduced folates in the soluble fraction, 56% in the mitochondrial, 55% in the nuclear, 20% in the lysosomal, and 15% in the microsomal fraction.

Acid Phosphatase↗
PubMed1976

The availability of folates in man: effect of orange juice supplement on intestinal conjugase.

The mechanisms of the low availability of endogenous folates in orange juice and the inhibitory effects on the availability of pteroylheptaglutamate (PteGlu7) caused by orange juice supplements were investigated in man by the use of simulated orange juice (containing the principal components: citric acid, malic acid, etc.) with several different pHs. The endogenous folates in orange juice were identified as mainly 5-methyl reduced derivatives of pteroylpolyglutamates (40-45% pentaglutamate, 10-15% tetraglutamate, 30-40% monoglutamate, and the rest were tri-and diglutamates). The availability of PteGlu7 is decreased to 54% by supplementation with 600 g concentrated orange juice (pH 3.7) and to 39% and 66% by the supplement of 24 g and 12 g citric acid (pH 3.7), respectively. Neutralization of 12 g citric acid to pH 6.4 largely reverses the inhibitory effect. On the other hand, the availability of pteroylmonoglutamate (PteGlu) is not influenced by a supplement of orange juice or citric acid. The results suggest that the low availability of PteGlu7 is due to the inhibition of intestinal conjugase caused by the low pH. These observations suggest that pH of foodstuffs may be an important factor in the absorption of polyglutamate forms of folate.

Adult↗
PubMed1975

The relationships between vitamin B12 and folic acid and the effect of methionine on folate metabolism.

The relationship between vitamin B12 and folate and the effect of methionine on folate metabolism during B12 deficiency in rats is best explained by the prevention of the accumulation of 5-methyl-H4PteGlu by vitamin B12 and/or methionine. Although several points remain to be clarified, the 'methyl trap' hypothesis provides the most satisfactory explanation for the relation between vitamin B12, methionine and folic acid. This concept is extended by the hypothesis that H4PteGlu is the most active substrate for pteroylpolyglutamate synthetase, and thus accounts for the effect of methionine or vitamin B12 increasing liver folate levels.

Animals↗
PubMed1975

Studies of folic acid compounds in nature. IV. Folic acid compounds in soybeans and cow milk.

Folate compounds in soybean and cow's mild were identified by Sephadex chromatography and differential microbiological assaymsoybean contained mainly monoglutamates (ca. 52%), some diglutamates (ca. 16%), and polyglutamates (pentaglutamates representing the major portion). 5-CHO-H4PteGlun(1-6) constituted 65-70% of total folate activity; Cow's milk contained monoglutamates (60%) and polyglutamates (ranging from di- to hepta-conjugates). In contrast to soybean, 90-95% of milk folate was in the 5-CH3h4pteGlun(1-7) form.

Animals↗