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Biomedical subjects

Y Muto

Publications and source records attributed to Y Muto.

At least 505 records · Page 28Linked to original sources
PubMed1977

Long-term effect of medium-chain triglyceride on hepatic enzymes catalyzing lipogenesis and cholesterogenesis in rats.

This study was conducted to investigate the long-term effect of dietary medium-chain triglyceride (MCT) as compared with that of corn oil feeding on lipid metabolism in rats. Both serum cholesterol and triglyceride levels in MCT-fed rats showed significant decrease during the experimental period of eight weeks, although liver cholesterol and triglyceride contents were not distinguishable between the two groups. Significant elevation of the activity of lipogenic enzymes, such as fatty acid synthetase (FAS) and malic enzyme (ME) of the liver, was observed in MCT-fed rats without any fat accumulation of the liver (fatty liver). The increase of lipogenic enzyme activity was accompanied by a significant reduction of essential fatty acids (EFA) such as 18:2 (omega6) and 20:4 (omega6) in total liver lipid. In contrast, hepatic beta-hydroxy-beta-methylglutaryl CoA(HMG-CoA) reductase activity was significantly decreased in MCT-fed rats, that would play an important role in achieving hypocholesterolemia. From these results obtained in a long-term experiment, it is concluded that exogenous MCT depresses the key enzyme catalyzing cholesterol synthesis with a concomitant elevation of lipogenic enzyme activity in the rat liver.

Animals↗
PubMed1977

Vitamin A transport in plasma of the non-mammalian vertebrates: isolation and partial characterization of piscine retinol-binding protein.

Studies were conducted to explore vitamin A transport in the non-mammalian vertebrates, especially Pisces, Amphibia, and Reptilia, and to isolate and partially characterize piscine retinol-binding protein. Retinol-containing proteins in fresh plasma obtained from bullfrogs and a turtle exhibited similar properties to those found in mammalian and chicken plasma: i.e., molecular weight of about 60,000-80,000 as estimated by gel filtration and binding affinity to prealbumin on human prealbumin-Sepharose affinity chromatography. In sharp contrast, vitamin A-containing proteins in plasma from larvae of bullfrogs as well as three fishes (carp, blue sharks, and young yellowtails) appeared to be present in plasma as monomeric retinol-binding proteins without any affinity to human prealbumin. On the other hand, plasma vitamin A in the lamprey (Cyclostomes) was found to exist exclusively as an ester form in association with the lipoproteins of hydrated density less than 1.21 g/ml. Piscine retinol-binding protein was isolated from pooled plasma of young yellowtails and was converted (1000-fold purification) to a homogeneous component by a procedural sequence that included gel filtration on Sephadex G-100, chromatography on SP-Sephadex, gel isoelectric focusing, and, finally, polyacrylamide gel electrophoresis. Purified piscine retinol-binding protein showed physico-chemical properties distinctly different from the mammalian and chicken retinol-binding proteins examined, i.e., a smaller molecular weight of approximately 16,000, a lower isoelectric point of 4.3, a prealbumin mobility on analytical polyacrylamide gel electrophoresis, and a lack of binding affinity for human prealbumin; however, it displayed similar characteristics in two ways: a 1:1 molar complex with retinol, and a high content of tryptophan (four residues). These results strongly suggest that the piscine retinol-binding protein is a prototype of the specific vitamin A-transporting protein in plasma of the vertebrates, being modified later in evolution, during phylogenetic development of the vertebrates, to acquire a binding site for prealbumin on the molecule.

Amino Acids↗
PubMed1977

Decrease of seminolipid content in the testes of rats with vitamin A deficiency determined by high performance liquid chromatography.

Changes of seminolipid content in vitamin A-deficient rat testes were quantitatively determined by improved and facile high performance liquid chromatography using a reversed phase column under an ion pair chromatographical condition. The seminolipid content of the testes of rats fed a vitamin A-deficient diet for 46 days decreased to 13% of that of the control rats fed a vitamin A-deficient for 20 days and then supplemented with 140 microgram/rat/day of vitamin A palmitate for 26 days. Total lipid, phospholipid and DNA of vitamin A-deficient rats were slightly reduced. Histological examinations showed that seminiferous tubular cells degenerated to aspermatogenesis with a vitamin A-deficient diet. The remarkable reduction of seminolipid content, compared to the slight decrease of DNA content, is considered to be the result of damage to the seminiferous tubular elements, especially at the differentiated step of germinal cells from spermatogonia to the next. These results further support the theory that seminolipid biosynthesis is characterized by strict dependence on the differentiation of seminiferous tubular cells or spermatogenesis.

Animals↗
PubMed1976

Urinary excretion of retinol-binding protein (RBP) in rabbit chronically poisoned with cadmium. Isolation and partial characterization of rabbit RBP.

Studies were conducted to induce urinary excretion of retinol-binding protein (RBP) in the rabbit by long-term administration of cadmium, and to isolate and characterize rabbit RBP. Two rabbits were exposed to Cd at a dose of 0.8 and/or 1.5mg/kg of body weight by means of subcutaneous injections five times per week. One rabbit excreted large amounts of protein (0.8 to 1.6 g/day) from days 80 to 118. The electrophoretic patterns of the urinary protein showed two fluorescent bands specific for protein-bound retinol in the alpha-region; these were presumed to be RBP. Rabbit RBP was isolated from the pooled urine (10.3 liters) by a sequence of procedures which included gel filtration on Sephadex G-100 and chromatography on DEAE- and SP-Sephadex. Purified RBP (20 mg) was found to be homogeneous by physical and immunological criteria. The RBP had alpha-mobility, with a molecular weight of approximately 20,000. The properties of rabbit RBP resembled those of human RBP simultaneously isolated from the urine of patients with "Itai-Itai" disease in many ways: ultraviolet and fluorescence spectra, and amino acid compositions. A monospecific anti-rabbit RBP antiserum was raised in a goat. There was no immunological cross-reactivity between rabbit and human RBP. The molecular size of the retinol-containing protein in fresh rabbit serum was estimated to be about 60,000 to 70,000 by gel filtration on Sephadex G-200. Rabbit RBP in the serum was also shown to be immunologically identical with purified RBP from the urine.

Amino Acids↗
PubMed1976

Partial characterization of molecular species of retinol-binding protein found in tubular proteinuria due to chronic cadmium poisoning in the rabbit.

A study was conducted to characterize the molecular species of retinol-binding protein (RBP) isolated from the urine of rabbits chronically poisoned with cadmium. The RBP species, identical with regard to both molecular size (approximately 20,000) and immunoreactivity, were separated into four fractions by means of polyacrylamide gel electrophoresis (PAGE), which yielded two holo-RBP (H2 and H1) and two apo-RBP (A2 and A1) species. The urinary excretion ratio of these fractions (H2 : H1 : A2 : A1) was found to be about 70 : 6 : 21 : 3. No distinct difference of amino acid composition between holo- and apo-RBP was observed. An additional species of apo-RBP (designated An) was also isolated from theaged holo-RBP (H2) by isoelectric focusing in gel. Using the separated molecular species of rabbit RBP as well as of human RBP, their interactions with human prealbumin (PA) were examined both by human PA-Sepharose affinity chromatography, and by gel filtration on Sephadex G-100 after in vitro incubation of the RBP with human PA. Purified rabbit holo-RBP exhibited almost the same binding ability to human PA as did human RBP. Retinol within RBP molecule enhanced the affinity to PA, resumably through the change of tertiary structure, although the presence of retinol was not essential for the protein-protein interaction.

Amino Acids↗
PubMed1975

Effect of exogenous polyunsaturated fatty acids on lipogenic enzyme activity in rat liver under fixed carbohydrate consumption.

Studies were conducted to evaluate specific dampening of hyperlipogenesis (i.e. enhanced lipogenic enzyme activity of the liver in rats refed a high carbohydrate, fat-free diet: F-diet) by exogenous polyunsaturated fatty acids under fixed carbohydrate consumption. In force-feeding of rats with a linoleate-rich diet (F-diet containing 4.5% safflower oil), the lipogenic enzyme activities; fatty acid synthetase (FAS) and malic enzyme (ME) in the liver supernatant were found to be significantly lower than those in rats force-fed only an F-diet (p is less than 0.02), under conditions of identical consumption of carbohydrate. Among the various methylestery of unsaturated fatty acids administered by gastric intubation at a dose of 0.3 g per 100 g body weight, arachidonate was most potent in bringing about a significant reduction of hyperlipogenesis without seriously affecting food intakes. During the same three-day experimental period, fatty acid GLC spectra in both the liver and plasma lipids reflected the exogenous input of PUFA. Plasma total fatty acid concentration (mainly triglyceride) signigicantly decreased in the arachidonate group (p less than 0.01).

Animal Nutritional Physiological Phenomena↗
PubMed1975

Tissue distribution and subcellular localization of retinol-binding protein in normal and vitamin A-deficient rats.

Levels of retinol-binding (RBP), the plasma transport protein for vitamin A, were measured by radioimmunoassay in sera and in a large number of tissues from both normal and vitamin A-deficient rats. The tissues included liver, kidney, fat, muscle, brain, eye, salivary gland, thymus, lung, heart, intestine, spleen, adrenal, testes, thyroid, and red blood cells. The RBP levels in tissues other than serum, liver, and kidneys varied from 12 mug/g of tissue for normal spleen to an undetectable level in red blood cells. Much of the RBP in the tissues with low levels may have been due to residual serum in the samples. In general, except for liver, RBP levels were lower in tissues from vitamin A-deficient rats than in those from normal rats. In normal rats, the liver, kidney, and serum levels were 30 plus or minus 4 (mean plus orminus SEM), 151 plus or minus 22, and 44 plus or minus 3 mug/g, respectively. In vitamin A-deficient rats, the liver RBP level was about three times the normal level whereas the kidney and serum levels were about one-fifth the normal values. When normal liver homogenates were fractionated by centrifugation, 67% of the RBP was recovered in the microsomal fraction and only 9% was found in the soluble 105,000 g supernate. In contrast, 76% of the RBP in homogenates of normal kidneys was in the soluble fraction. Similar results were obtained with deficient livers and kidneys. Incubation with deoxycholate released the liver RBP into the soluble fraction. RBP is produced in the liver and removed from the blood by the kidneys. The levels of RBP in normal and deficient liver, serum, and kidney appear to reflect the relative rates of RBP secretion and turnover.

Adipose Tissue↗
PubMed1975

[Therapeutic effect of sulfobenzyl-penicillin (SB-PC) on the concentration of SB-PC in human bile (author's transl)].

Sulfobenzyl-penicillin (SB-PC) is currently being investigated for use in man. The purpose of this study was to evaluate effect of SB-PC on Salmonella typhosa and biliary excretion of SB-PC in disease of the biliary tract. 1) Clinically, typhoid carriers without cholelithiasis were initiated with 4.0 g/day of SB-PC. Stool and bile became negative for Salmonella typhosa 14 days after initial treatment. 2) In typhoid carriers with cholelithiasis, Salmonella typhosa were not isolated from bile, wall of the gallbladder and surface of gallstone, but were isolated from nuclei of gallstones. The treatment of typhoid carriers with cholelithiasis may belong to a most difficult problem. 3) Biliary excretion of SB-PC in the patient given a single dose of 2.0 g/day im. was markedly dependent on characteristics of the patient, situation of external drainage and volume of bile excretion. High concentration in bile in some patient was 298 mug/ml at 3 hours after administration. 4) In intravenous administration of single dose of 6.0 g. maximum concentration in bile was about 2,000 mug/ml at 2 hours after administration and bactericidal concentration was obtained for resistant bacteria (Pseudomonas, Proteus, etc.) in biliary infection. 5) As side effects, pain and redness were infrequent after im. administration. Toxicity was not experienced in the patients injected intravenously.

Aged↗