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Biomedical subjects

B H Cho

Publications and source records attributed to B H Cho.

70 records · Page 4Linked to original sources
PubMed1985

Sugar specificity and sugar-proton interaction for the hexose-proton-symport system of Chlorella.

The substrate specificity of the glucose-proton symport system was studied to gain information about the spatial relationship between the binding sites for glucose and proton. Charged glucose analogues such as amino sugars or sugar acids were not transported by the uptake system, with the exception of 2-amino-2-deoxy-D-glucose. This glucosamine was taken up in the charged form in uniport mechanism, i.e. without symport of proton. This result was interpreted to mean that the proton-binding site of the symport system is close to the hydroxyl at carbon 2 of glucose. This interpretation was strengthened by the following facts: The steric position of hydroxyl groups at carbons 1, 2 or 3 of glucose were especially important for efficient transport. O-Methylation was not tolerated at carbon 1, but it was tolerated at carbons 3, 4 or 6. The stoichiometric flow of proton and sugar could be disturbed by removal of hydroxyl group at carbon 1 of glucose. The pH-dependence of sugar transport is sugar-specific, e.g. the amino group at carbon 2 of glucose improves transport at higher pH. The configuration at carbon 2 of glucose influences the specificity for the symported ion. It is concluded that the coupled flow of proton and glucose occurs by simultaneous coordinate movement of both in a transmembrane channel.

Biological Transport↗
PubMed1985

Plasma lipid and lipoprotein cholesterol levels in swine. Modification of protein-induced response by added cholesterol and soy fiber.

Piglets, aged 8 weeks and weighing 12-18 kg, were fed semi-purified casein or soy protein diets, with or without cholesterol and soy hull fiber, for 2 months. In addition to observing the effects of the dietary treatments on growth, the modification of the primary hypocholesterolemic action of soy protein by cholesterol and soy fiber was studied. Pigs fed the soy protein or casein diets grew normally with no difference in weight gain. Plasma triglyceride and phospholipid levels, as well as several plasma metabolic indices examined, were not significantly affected by dietary treatment. However, plasma total cholesterol was higher (but not significantly) in pigs fed casein than in those fed soy protein alone. Cholesterol feeding induced markedly significant (P less than 0.05) hypercholesterolemia with either protein source, compared to feeding the proteins without added cholesterol. Dietary soy fiber fed simultaneously with cholesterol decreased the cholesterol-induced hypercholesterolemia, but the reduction was significantly greater (P less than 0.05) with soy protein than with casein in the diet. Analyses of the lipoprotein cholesterol indicated that LDL cholesterol was much more sensitive to the changes induced by feeding cholesterol and soy fiber than either HDL or VLDL cholesterol. These findings suggest a beneficial role of dietary soy fiber in hypercholesterolemia.

Animals↗
PubMed1984

Ultrastructural changes in the comb and aorta of chicks fed excess testosterone.

The mode of cellular response to testosterone was monitored in the combs and aortas of chicks with the aid of an electron microscope. A 7-week treatment of 30 mg of testosterone per day had little effect on plasma lipid metabolism. However, this treatment resulted in the activation of fibroblasts in the comb, activation of fibroblast-like and smooth muscle cells in the aorta, and degeneration of smooth muscle cells in the aorta. A treatment of 150 mg of testosterone per day for 7 weeks induced hyperlipidemia and lipid-rich aortic lesions. The abdominal aorta had more activated and degenerated smooth muscle cells, with or without stainable lipid droplets, than the ascending aorta.

Animals↗
PubMed1983

Lipid composition and cholesterol esterifying activity in microsomal preparations of porcine coronary arteries and heart tissue.

Lipid composition and cholesterol esterifying activity were determined in microsomal preparations from coronary arteries and heart tissues of swine. There was a higher concentration of free cholesterol in coronary arteries than in the heart, whereas phospholipid was more concentrated in the heart compared to the coronary arteries. Esterified cholesterol was a minor form of cholesterol in both tissues. Individual classes of microsomal lipids possessed characteristic fatty acid spectra and a number of differences were noted between coronary arteries and heart tissue. The portion of microsomal polyunsaturated fatty acids, particularly linoleic acid, was notably higher in the cholesteryl ester, free fatty acid, and phospholipid fractions of heart tissue compared to the corresponding lipid fractions of the coronary arteries. Cholesterol esterifying activity, measured with 14C-labeled fatty acids, was fairly low in coronary arteries, but considerable activity was present in heart tissue. Oleic acid substrate esterified cholesterol most effectively, followed by linoleic and elaidic acid. Under the incubation conditions for cholesterol esterifying activity, however, the bulk of the fatty acid was actively incorporated into phospholipid rather than cholesteryl ester or triglyceride. Among the fatty acids tested, linoleic acid was the most preferential substrate for phospholipid synthesis and phospholipid synthesizing activity was much greater in heart tissue than in coronary arteries.

Animals↗
PubMed1983

Lipid composition and lipogenic activities in the livers of normo- and hereditary hyperlipidemic chickens.

Lipid content of the liver and its lipogenic activities were compared among year-old laying hens and hereditary non-layers and roosters fed a low-fat and cholesterol-free grain diet. In contents of free cholesterol, cholesteryl ester and phospholipid, the differences between groups were relatively minor, but striking differences were noted in triglyceride with a marked accumulation in non-layers. Incorporation studies of [14C]acetate and [14C]mevalonate by liver slices revealed that in layers, acetate was preferentially incorporated into saponifiable lipids (SF), whereas mevalonate incorporated actively into both saponifiable and non-saponifiable (NSF) lipids. Lipid synthesis with acetate and mevalonate was extremely low in non-layers; in roosters, utilization of acetate was very poor but mevalonate was actively incorporated into SF and NSF lipids. During incubation of tissue slices, acetate was extensively oxidized to CO2, whereas mevalonate was poorly oxidized in all chickens. The level of substrate oxidation was similar between layers and roosters, but their level of oxidation was much greater than that of non-layers.

Acetates↗
PubMed1983

Improved enzymatic determination of total cholesterol in tissues.

In this improved method for rapid enzymatic determination of total cholesterol, the lipid extracts from tissues are dissolved in an equal volume of peroxide-free dioxane/isopropanol (50/50 by vol) solution, and are reacted directly with the aqueous enzymatic reagent, without further treatment. The presence of organic solvents, such as dioxane and isopropanol, does not interfere with enzymatic activity. This simpler procedure eliminates the tedious solubilization of tissue lipid extracts into an aqueous medium. The method is reproducible, and results correlate well with those by a chemical (FeCl3/H2SO4) method.

1-Propanol↗
PubMed1981

Glucose induces two amino acid transport systems in Chlorella.

In autotrophically grown Chlorella cells, glucose induces a hexose transport system but, at the same time, the synthesis of two amino acid transport systems is also induced. Thus, the rates of uptake of glycine, L-alanine, L-proline, and L-serine, all of which compete with each other for entry into the cells, increase more than 100-fold when the algae are pretreated with glucose. The rates of L-arginine and L-lysine uptake increase by a factor of 25 to 50. The accumulation of proline and arginine within the cells amounts to 200- and 600-fold, respectively. Glucose does not cause the positive effect on amino acid uptake by serving as metabolic substrate because the nonmetabolizable 6-deoxyglucose also acts as inducer. Cycloheximide prevents the induction. The induced transport system for the four neutral amino acids has a turnover with a half-life of 7 hr, which corresponds closely to the half-life of the hexose transport system. The transport system for the basic amino acids, on the other hand, disappears with a half-life of 25 hr.

Alanine↗
PubMed1980

Aortic lesions in nonlaying hens with endogenous hyperlipidemia.

Atherogenicity of chemically discrete cholesterol has been questioned earlier at small doses insufficient to cause hypercholesterolemia. Long-term experiments involving large doses are hindered by the propensity of cholesterol to autoxidize in air. As an alternative, aortic lesions in mature, 1- to 3-year-old laying and hereditary nonlaying hens were studied by electron microscopy. Due to spontaneous egg yolk involution, serum cholesterol values of nonlayers were high, averaging 583 mg/dL, and triglyceride values averaged 1,777 mg/dL. Respective values in layers were 106 mg/dL and 894 mg/dL. Aortic lesions in nonlayers developed earlier and were more extensive and fatty than in layers. Lipids were stainable even in the media of grossly normal segments of aorta in nonlayers. Findings suggested an important role of inhibition of hyperlipidemic components. It is unknown, however, whether large amounts of endogenous cholesterol in serum undergo autoxidation in vivo.

Animals↗
PubMed1977

Aortic intimal changes in aging swine.

Aortic intimal lesions in aging swine contained smooth muscle, monocyte-like and unclassifiable cells. The most frequent cellular constituent was the smooth muscle cell that had slightly different features than those in the media. Monocyte-like and unclassified cells appeared largely in the innermost layer of the intima; both types of cells were ultrastructurally similar in appearance except the former had heterophagic vacuoles and overall resemblance to circulating monocytes in shape and size. These cells seemed to preexist in aortic lesions of untreated, aging swine. The intima-media strips of the grossly normal thoracic aortas in 3 1/2 year old swine showed significantly higher contents of cholesterol, triglycerides, phospholipids and total lipids than those of a 6 month old swine. Three to four month old cultured aortic cells accumulated extracellular components, such as fibriles, electron dense substances and cellular debris, which appeared similar to the extracellular matrix of aortic plaques in aged swine.

Aging↗
PubMed1976

Additive risk factors in atherosclerosis.

The tissues of human subjects assayed for a higher level of vitamin D than the tissues of 6-month-old swine which had been fed a commercial ration containing 14 times more vitamin D3 than the National Research Council recommended requirement for growing swine. Bioassays of commercial livestock feeds indicate much higher vitamin D contents than the National Research Council recommendation. High levels of vitamin D activity are demonstrable in tissues from the animals on such livestock feeds. The grossly normal areas of the aorta of weanling swine fed 100,000 IU of vitamin D3/pound of basal ration during the initial 6 weeks had a higher frequency of degenerated smooth muscle cells than the grossly normal areas of the aorta of swine fed the commercial ration, or 7.43+/-0.45 and 5.60+/-0.27/100 cells, respectively, at the age of 3 months. Tbe addition of 13 pounds of hydrogenated fat and 200 g of cholesterol/100 pounds of the commercial ration further increased the frequency of degenerated smooth muscle cells by 0.53 (P less than 0.05) or to 7.96 +/- 0.39/100 cells in the grossly normal areas of the aorta of weanling swine fed this fat-supplemented ration to 3 months of age.

Adipose Tissue↗
PubMedDate not supplied

Gene expression analysis in cucumber leaves primed by root colonization with Pseudomonas chlororaphis O6 upon challenge-inoculation with Corynespora cassiicola.

Root colonization by Pseudomonas chlororaphis O6, a non-pathogenic rhizobacterium, induced systemic resistance in cucumber against target leaf spot caused by Corynespora cassiicola. A cDNA library was constructed using mRNA extracted from cucumber leaves 12 h after inoculation with C. cassiicola, using plants colonized by O6. To identify genes involved in O6-mediated induced systemic resistance (ISR), we employed a subtractive hybridization method using mRNAs extracted from pathogen-challenged cucumber leaves of plants lacking colonization. Differential screening of the cDNA library led to the isolation of six distinct genes encoding a GTP binding protein, a 60S ribosomal protein, a hypersensitive-induced reaction protein, a ubiquitin extension protein, a pyridine nucleotide-disulfide oxidoreductase, and a signal recognition particle receptor. Expression of these genes was not induced by O6 colonization alone. Rather, transcript accumulation of these genes increased significantly faster and stronger in the O6 colonized than in non-colonized plants after challenge infection. Therefore, O6-mediated ISR may be associated with an enhanced capacity for the rapid and effective activation of cellular defence responses after challenge inoculation.

Ascomycota↗
PubMedDate not supplied

The role of neutrophils in tissue localized cell-mediated immunologic responses: I. The intensity of contact-type and delayed-type hypersensitivity responses may be influenced by the extent of extracellular matrix degradation by neutrophil proteases.

Studies were undertaken to evaluate factors capable of influencing the intensity of contact hypersensitivity (CH) and delayed-type hypersensitivity (DTH) responses in mice. It is well known that the exposure of animals to ultraviolet radiation (UVR) causes a depression of CH and DTH responses whereas the injection of mice with nanogram quantities of pertussis toxin (PT) before sensitization results in greatly augmented CH responses following hapten challenge. Histopathology and biochemical quantitation of myeloperoxidase (MPO) activity in biopsies obtained from the challenged ears from normal, UVR-exposed, or PT-treated animals determined that a direct correlation existed between the intensity of the ear-swelling response and the degree of neutrophil infiltrate into the challenge site. Few neutrophils were observed to infiltrate into the ears of UVR-exposed animals when compared to normal animals, whereas a pronounced neutrophil infiltration was observed in the challenged ears of PT-pretreated animals. These observations led us to question whether tissue-infiltrating neutrophils, or their products, might be involved in controlling the intensity of CH and DTH responses. The direct injection of murine neutrophils, neutrophil homogenates, and a neutrophil granular fraction into the ear pinnae of normal mice resulted in a dosage-dependent ear-swelling reaction after 24 hours that was histologically similar to antigen-induced CH or DTH responses (primarily mononuclear cell infiltrate). Additional studies determined that an injection of elastase, collagenase, or peptides of elastin or collagen generated by elastase or collagenase treatment of insoluble elastin or collagen also caused a pronounced ear-swelling accompanied by a mononuclear cell infiltration. On the basis of these studies, coupled to experiments that demonstrated an inhibitory influence of alpha-1-antitrypsin (alpha 1-AT) on CH and DTH responses, we propose that neutrophil proteases may play an important role in regulating the intensity of CH and DTH responses in mice through their capacity to degrade extracellular matrix proteins whose peptide fragments are chemotactic for mononuclear cells and fibroblasts.

Animals↗