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Biomedical subjects

L H Chen

Publications and source records attributed to L H Chen.

At least 127 records · Page 7Linked to original sources
PubMed1986

Vitamin C partially reversed some biochemical changes produced by vitamin E deficiency.

Feeding a basal diet free of vitamins E and C to weanling male rats for 8 months resulted in biochemical changes characteristic of vitamin E deficiency. These included increased liver thiobarbituric acid values; decreased blood GSH levels, plasma vitamin E levels, and glutathione peroxidase activities; and increased activities of plasma pyruvate kinase, glutamic-oxaloacetic transaminase, creatine kinase, lactic dehydrogenase, and malic dehydrogenase. Tube-feeding vitamin C for 21 days resulted in partial reversal effects on the above parameters except activities of glutathione peroxidase, lactic dehydrogenase, and malic dehydrogenase. The results suggest that vitamin C may spare in part the metabolism of vitamin E through its antioxidant property.

Animals↗
PubMed1985

Survey of drug use by the elderly and possible impact of drugs on nutritional status.

The drug consumption of institutionalized and noninstitutionalized elderly in the central Kentucky area was surveyed. The 259 subjects above age 60 were randomly selected and consisted of 122 institutionalized and 137 noninstitutionalized subjects. Individual data on age, sex, drug intake, dosage, and health status were recorded. The drugs taken were categorized by their pharmacological action, and the number of subjects on each drug was recorded. Institutionalized elderly subjects had a significantly higher drug intake (average 5.2 drugs a day) than noninstitutionalized elderly subjects (average 1.6 drugs a day). A consistent increase was found in the average number of drugs used with increasing age. The results also showed that the medications most frequently used were drugs used for cardiovascular disease, for the central nervous system, and for constipation. Aspirin and Tylenol were also commonly used. Institutionalized elderly subjects had especially high intakes of these drugs. The possible impact of these drugs on the nutritional status of the elderly was discussed. Some medications for long-term use may exert serious adverse effects on the nutritional status.

Aged↗
PubMed1984

Dietary vitamin E and pulmonary biochemical responses of rats to cigarette smoking.

The effect of dietary vitamin E on cellular susceptibility to cigarette smoking was studied in rats. Young male rats maintained on a basal vitamin E-deficient diet with or without 100 ppm vitamin E supplementation for 4 or 5 weeks were exposed to either sham or cigarette smoke for up to 7 days. Higher animal mortality rate was observed in the animals fed the vitamin E-deficient diet than in the supplemented group when they were subjected to acute levels of cigarette smoking. Relative to the respective sham groups, a greater alteration of biochemical parameters, such as reduced glutathione (GSH) and related enzymes, was found in the lungs of smoked rats fed the deficient diet than in the supplemented group. Animal lungs exhibited a greater biochemical response to whole smoke than the gaseous phase of smoke. The results suggest that the nutritional status of vitamin E may influence the cellular susceptibility of rats to cigarette smoking.

Animals↗
PubMed1983

A comparative study of polyclonal and monoclonal antibodies for immunocytochemical localization of cytosolic aspartate aminotransferase in rat liver.

The rabbit antiserum and mouse monoclonal hybridoma antibody against porcine cytosolic aspartate aminotransferase (c-AAT) (or cytosolic glutamic oxaloacetic transaminase (c-GOT)) were produced and compared for the localization of c-AAT in rat liver. An indirect immunocytochemical technique was performed using peroxidase-conjugated goat immunoglobulin (Ig) G anti-rabbit IgG and peroxidase-conjugated rabbit IgG anti-mouse IgG as the second antibody. Rats were perfused with paraformaldehyde-lysine-periodate fixative and the liver fragments were immersed in 4% paraformaldehyde and transferred to 10% dimethyl sulfoxide overnight and subjected to cryostat sectioning. The rabbit IgG antibody, 3 individual monoclonal antibodies, and a mixture of these 3 monoclonal antibodies were applied to the tissue sections, respectively, using the same concentration. Under the same experimental conditions, the c-AAT was localized in each individual hepatocyte by both monoclonal and polyclonal antibodies. However, a mixture of three monoclonal antibodies gave stronger staining than a single monoclonal antibody; although two antibodies yield more intense staining than just one, it was still less intense than for three. The conventional rabbit polyclonal antibody against c-AAT produced more reaction product than the combined three monoclonal antibodies. It is concluded that for immunocytochemical study, the use of a single monoclonal antibody is sensitive enough to localize its tissue antigen under the present experimental condition. To obtain a stronger reaction product, a combination of several monoclonal antibodies, at least three or more, may give better staining.

Animals↗
PubMed1983

Production and characterization of an antibody to cytosolic aspartate aminotransferase and immunolocalization of the enzyme in rat organs.

Cytosolic aspartate aminotransferase (c-AAT) was purified to homogeneity from porcine heart and immunized to rabbit for production of antiserum. The purity of this enzyme protein and the specificity of its antibody were judged by silver-stained-sodium dodecyl sulfate slab gel, Western blot transfer technique, and double immunodiffusion. The antibody against porcine heart c-AAT was found to cross-react with rat c-AAT but not with nine other different enzymes from the heart, liver, and muscle. Affinity purified antibody was used to localize this isoenzyme in the rat heart, liver, kidney, and cerebellum by indirect immunoperoxidase method. It was found that, in the rat heart muscle, c-AAT reaction product was present as a linear structure parallel to the muscle fiber and along the sarcolemma. Some cardiac muscle fibers contain more reaction products than the others. In the liver, reaction product was seen unevenly distributed in the hepatocytes. The Kupffer cells and endothelia were less stained. Most of the tubular epithelia of the loop of Henle in the kidney were intensely stained. But other tubular epithelia including convoluted and collecting tubules were sporadically and less stained. The basket and stellate cells and their neuronal processes and terminals in the cerebellum were markedly stained, but the Purkinje and granule cell bodies were weakly stained. For comparison of the staining intensity with enzyme activity in each organ, the c-AAT enzyme activity was simultaneously determined in those organs. This study indicates that the presence of c-AAT is specific in different organs and tissues.

Animals↗
PubMed1983

Plasma creatine kinase isozyme electrophoretic pattern of long-term vitamin E-deficient rats.

Weanling male Sprague Dawley rats were fed a vitamin E-deficient basal diet with or without supplementation of 100 IU/kg diet of vitamin E for 12 months. The isozyme pattern of creatine kinase (CPK) in plasma was determined electrophoretically. The CPK activity of the plasma of control rats averaged 43.2 nmoles/min/ml and was predominantly CPK3 isozyme, while that of the plasma of vitamin E-deficient rats averaged 100.8 nmoles/min/ml and consisted of CPK2 and CPK3 isozymes. The results suggest that the increased CPK activity in the plasma of vitamin E-deficient rats may originate from heart and skeletal muscle degeneration.

Animals↗
PubMed1982

Ultrastructural and lysosomal enzyme studies of skeletal muscle and myocardium in rats with long-term vitamin E deficiency.

Muscular dystrophy and cardiomyopathy were produced in weanling rats by feeding a vitamin E-deficient diet for 12 mth. Deficient and control rats were killed, and skeletal muscle and myocardium were used for subcellular studies and biochemical assay of selected lysosomal enzymes. Ultrastructurally, the skeletal muscle showed various degrees of pathological changes. In the severely damaged muscle fibres, prominent increase of secondary lysosomes, autophagic vacuoles, residual bodies, disappearance of myofilaments, rupture of sarcolemma and shrinkage of muscle fibres were noted. The damaged muscle fibres finally became dense residual bodies and dispersed in the interstitial spaces, where the macrophages and fibroblasts were found. In the myocardium, some muscle fibres were intact with mild fatty infiltration and marked proliferation of mitochondria. However, in the severely damaged myocardial fibres, the whole fibre was always filled with amorphous dense bodies, and the sarcolemma was ruptured. This resulted in dispersion of many cellular organelles in the surrounding interstitial space. A significant increase of cathepsin and beta-glucuronidase activity in the cytosol of both organs suggests that lysosomal enzymes may play a major role in the destruction of muscle and cardiac fibres in the long-term vitamin E-deficient animals.

Animals↗
PubMed1982

Effect of dietary vitamin E on the aryl hydrocarbon hydroxylase activity of various tissues in rat.

Weanling male Sprague Dawley rats were maintained on a vitamin-E deficient basal diet with or without supplementation of 100 ppm vitamin E per kg diet. The animals were sacrificed after 12 months and S-9000 xg microsomal supernatants were prepared from liver, testes, skeletal muscle, heart and kidney tissues. High spontaneous hemolysis of erythrocytes and low levels of plasma vitamin E confirmed the deficiency status of rats in the deficient group. Aryl hydrocarbon hydroxylase (AHH) activity determinations on tissue S-9000 xg supernatants showed that while there was a slight reduction in the hepatic AHH, a marked increase in the AHH activity of other tissues occurred. The results obtained suggest a differential effect of dietary vitamin E on the tissue AHH activity in rats.

Animals↗
PubMed1981

An increase in vitamin E requirement induced by high supplementation of vitamin C in rats.

Weanling rats were maintained on purified diets with graded levels of vitamin E at 50, 60, 100, 200, or 500 IU/kg diet; each group was further divided into two subgroups, each with six rats and received vitamin C at 0 or 1.5 g/kg diet. After 1 or 2 months, the determination of antioxidant status showed that the high supplementation of vitamin C at the marginally adequate vitamin E level significantly increased in vitro erythrocyte hemolysis and liver lipid peroxidation, and significantly lowered erythrocyte level of reduced glutathione and plasma level of vitamin E; thus lowering the overall antioxidant potential of the animals. A small increase in vitamin E level counteracted the hemolytic and peroxidative effect of the high supplementation of vitamin C. A greater increase in vitamin E level counteracted the effect of high supplementation of vitamin C in decreasing glutathione level and plasma vitamin E level. These results indicate that the adverse effect of the high supplementation of vitamin C on tissue antioxidant potential may be overcome by increasing the supplementation level of vitamin E, and suggest that vitamin E requirement may be increased with increased vitamin C supplementation.

Animals↗
PubMed1981

Biochemical evaluation of riboflavin and vitamin B6 status of institutionalized and non-institutionalized elderly in Central Kentucky.

A study was conducted to assess the nutritional status of riboflavin and vitamin B6 of the elderly in Central Kentucky. Elderly subjects aged 60 to 95, including 42 men and 77 women, were randomly selected: 41 from six nursing homes and 78 from private residences. Blood and urine samples were collected for analysis. Riboflavin and vitamin B6 status were assessed by using glutathione reductase activation coefficient and glutamic-pyruvic transaminase activation coefficient, respectively. Glutathione reductase activation coefficients ranged from 0.88 to 1.89 with a mean +/- SD of 1.23 +/- 0.22, and were not significantly correlated with the urinary excretion of riboflavin. Glutamic-pyruvic transaminase activation coefficients ranged from 0.86 to 1.50 with a mean +/- SD of 1.16 +/- 0.14, and were negatively correlated with urinary excretion of 4-pyridoxic acid. Riboflavin deficiency was found in 34.2 percent of the institutionalized and 27.7 percent of the non-institutionalized subjects, while vitamin B6 deficiency was found in 56.6 percent of the institutionalized and 43.5 percent of the non-institutionalized subjects studied. The institutionalized elderly showed significantly poorer riboflavin status (P less than 0.01) and vitamin B6 status (P less than 0.05) than the non-institutionalized elderly. Aging was associated with a significant decline in both riboflavin (P less than 0.01) and vitamin B6 status (P less than 0.05).

Aged↗
PubMed1979

Factors affecting the physical performance of the rat in hyperbaric environments.

Experiments were designed to partition the effect of inspired oxygen tension (PIO2), gas density (rho), and ambient pressure (P) at rest and during exercise in rats. At rest oxygen uptake (VO2) was reduced by 19.5% (P less than 0.01) in 3 ATA air and by 32.1% (P less than 0.01) in 10 ATA air from 1 ATA air control of 29.3 +/- 1.21 (SE) ml/min.kg; there was no difference in VO2 between 1, 3, and 10 ATA He mixtures containing 20% O2. During exercise, VO2 was depressed by 36.2% (P less than 0.01) in 3 ATA air from 1 ATA air value of 55.3 +/- 3.23 ml/min.kg; VO2 was unaffected in 3 ATA He containing 20% O2 as compared to that of 46.5 +/- 2.43 ml/min.kg at 1 ATA He-O2 ambient. These VO2 values were compared to that obtained from normoxic ambients for separation of effects of elevated PIO2, P, and rho on VO2 at rest and during exercise. The effect of PIO2 was deduced by comparing VO2 in normoxic and hyperoxic He and N2 at a given P and rho. The density effect was obtained by comparing the VO2 in various densities at a given P and PIO2. The P effect was obtained by comparing the VO2 in various ambient pressures at a given rho and PIO2. Summation of the effects of P, rho, and PIO2 sufficiently approximates the changes in VO2 at rest. The same procedure underestimates the actually measured VO2 in all N2 ambients.

Air Pressure↗
PubMed1979

Effects of high level of vitamin C on tissue antioxidant status of guinea pigs.

Two groups of weanling male Hartley guinea pigs maintained on vitamin E deficient diet were supplemented with 0.4 I.U./100 g body weight/day of vitamin E and either 2 (Group A) or 10 (Group B) mg/100 g body weight/day of vitamin C for 5 weeks. As compared to Group A, the degree of erythrocyte hemolysis and liver TBAR level of Group B were significantly increased while plasma vitamin E and erythrocyte GSH levels were significantly decreased. In another experiment, two groups of guinea pigs were given 0.8 I.U./100 g body weight/day of vitamin E and 2 (Group C) or 30 mg/100 g body weight/day (Group D) of vitamin C. Levels of plasma vitamin E and erythrocyte GSH of Group D were significantly lower than those of Group C: however, erythrocyte hemolysis and liver TBAR were not affected by the level of vitamin C supplementation. The results suggest that the high levels of vitamin C supplementation lowered tissue antioxidant potential of animal when vitamin E was marginally adequate, and the hemolytic and peroxidizing effect of high level of vitamin C may be counteracted by increasing the level of vitamin E.

Animals↗
PubMed1978

Effect of dietary vitamin E and vitamin C on respiration and swelling of guinea pig liver mitochondria.

The effect of dietary vitamin C on vitamin E status and function was studied with weanling male Hartley guinea pigs. Thirty guinea pigs fed a basal diet free of vitamins E and C were divided into two groups; only one group received 2 mg/100 g body weight/day of vitamin C. Each group was further divided into three subgroups and received 0, 0.2, and 0.4 IU/100 g body weight/day of vitamin E. After 5 weeks the animals were killed. Degree of erythrocyte hemolysis induced by dialuric acid, level of plasma vitamin E and extent of liver lipid peroxidation were determined. Liver mitochondria were isolated and in vitro oxygen uptake was measured. The rate of swelling of mitochondria in two media was also determined. The results showed that the adequate dietary vitamin C supplementation did not affect the extent of erythrocyte hemolysis induced by dialuric acid, but increased the plasma vitamin E level and lowered liver lipid peroxidation. It also maintained the normal respiration and swelling rates of liver mitochondria when vitamin E was inadequate.

Animals↗
PubMed1977

Vitamin E status of Chinese population in Taiwan.

Vitamin E status of Chinese population with different age groups was studied by determining plasma vitamin E levels (PE) and hydrogen peroxide-induced erythrocyte hemolysis (HPEH). The mean PE of 99 adults, ages 23 to 78, was 1.05 +/- 0.47 mg/100 ml. There was no significant difference between sexes. PE was negatively correlated with HPEH (P less than 0.01). There was a significant positive correlation (P less than 0.01) between PE and plasma cholesterol level. The mean PE of four young men of Yami tribesmen, ages 16 to 19, was 0.60 +/- 0.10 mg/100 ml. HPEH was low. After daily supplementation of 200 mg dl-alpha-tocopheryl acetate for 16 days, PE increased 54%, but the plasma cholesterol was not affected. The mean PE of 39 elementary school children ages 12 to 13, was 0.70 +/- 0.31 mg/100 ml. The mean PE of 20 newborn infants was 0.23 +/- 0.08 mg/100 ml. HPEH was as high as 56.5 +/- 31.9% indicating a state of vitamin E deficiency. PE of total population was positively correlated with age (P less than 0.01). It was concluded that the vitamin E status of Chinese population in Taiwan was comparable to that of population groups in many other parts of the world.

Adolescent↗
PubMed1976

Topography of human plasma alpha1-acid glycoprotein.

Human plasma alpha1-acid glycoprotein, whose linear amino acid sequence has recently been elucidated (Schmid et al. (1973), Biochemistry 12, 2711), was further investigated with regard to its topography. Nitration of this protein and subsequent elucidation of the structures of the peptides containing modified tyrosine indicated that residues 27, 37, 78, 115, 127, and 157 are free, 50 and 91 are in an intermediate state, and 65, 74, 110, and 142 are buried. CD measurements between pH 10 and 12 demonstrated that the buried tyrosines are strongly hydrogen bonded and are probably responsible to a considerable extent for the stability of this protein. Of the three tryptophans of this protein, residue 122 proved to be partially reactive with Koshland reagent while the other two (25 and 160) were found to be unreactive. The state of the two disulfide bonds, established by differential reduction and alkylation with specific reagents, was shown to be of an intermediate type. Using carboxymethylation with bromoacetate at pH 7.0 for 8 days, the three histidines (97, 100, and 171) and methionine 111 could be shown to be in intermediate states. All lysines were treated with trinitrobenzenesulfonate and thus were assumed to be free. Of the 40 carboxylic groups, which were amidated with glycine methyl ester, 32 including the 14 sialyl residues were found to be free, six in an intermediate and the remaining two in a buried state. The present study describes the states of almost half of the amino acid residues of alpha1-acid glycoprotein, a knowledge important for the construction of a preliminary three-dimensional model of this conjugated protein.

Amino Acid Sequence↗