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Biomedical subjects

K H Yang

Publications and source records attributed to K H Yang.

At least 163 records · Page 9Linked to original sources
PubMed1983

Protective effect of Aucuba japonica against carbon tetrachloride-induced liver damage in rats.

Pretreatment of rats with ethanol extract from leaves of Aucuba japonica (600 mg/kg/day, po) for two days protected against CCl4-induced depression in plasma disappearance and biliary excretion of injected sulfobromophthalein (BSP) determined 24 hr after the CCl4 challenge (0.5 ml/kg, ip). Percent recovery of BSP in bile in 60 min for control, CCl4, extract + CCl4 treated rats was 66.8 +/- 1.9, 56.2 +/- 1.4, and 68.9 +/- 2.2, respectively. Pretreatment of the extract also protected CCl4-induced increased serum glutamic-pyruvic transaminase activity and liver necrosis as demonstrated by histological evaluations. However, pretreatment of the extract did not modify the intensity of CCl4-induced lipid peroxidation process or cytochrome P-450 destruction. The results suggest that ethanol extract of Aucuba japonica protects CCl4 hepatotoxicity at a site in the chain events leading to necrosis but not the activation step of CCl4 to X CCl3 and X C1 free radicals.

Animals↗
PubMed1983

Protective activities of aucubin against carbon tetrachloride-induced liver damage in mice.

An iridoid glucoside, aucubin was isolated from Aucuba japonica leaves and its protective activities against CCl4-induced hepatotoxicity were evaluated by measuring the duration of hypnosis induced by hexobarbital after CCl4 challenge (0.2 ml/kg/day, po) and the levels of serum glutamic-oxalacetic (GOT) and serum glutamic-pyruvic transaminase (GPT). The duration of hypnosis for the saline control group, the CCl4 alone treated group and the aucubin plus CCl4 treated group was 24.8 +/- 8.5, 60.5 +/- 9.5 and 28.0 +/- 3.2 min, respectively. Treatment of mice with aucubin also effectively protected against CCl4-induced increased serum GOT and GPT activities. It was found that aucubin inhibited hepatic RNA and protein syntheses in vivo. Such inhibitory effects of aucubin might be responsible for protective activities against CCl4-induced liver damage.

Alanine Transaminase↗
PubMed1982

Water vapor sorption and desorption by human callus I: Anomalous diffusion.

The rates of sorption and desorption of water in membranes of varying thickness of excised human callus were determined for several relative vapor pressures and temperatures. Under the conditions studied, the diffusion of water in these membranes was interpreted as non-Fickian in nature. It was concluded that at low water concentration this type of membrane exists in the glassy state. The effect of the relative vapor pressure on the water sorption rates was examined in the context of the free volume theory.

Adsorption↗
PubMed1979

In vivo methotrexate transport in murine Lewis lung tumor.

Methotrexate uptake by murine Lewis lung tumor was measured in vivo over a wide dose range. The data were analyzed according to a model previously developed for tissues in which methotrexate uptake is rate limited by transport across the cell membrane. Methotrexate transport in this tumor followed Michaelis-Menten kinetics with a rate constant for permeability (k/K) of 0.012 min-1. The methotrexate binding capacity of dihydrofolate reductase in the tumor was not exceeded at any dose studied. A low membrane permeability in conjunction with a high dihydrofolate reductase level explains the resistance of this tumor to methotrexate.

Animals↗
PubMed1977

Relative biochemical aspects of low and high doses of methotrexate in mice.

During low infusion rates of methotrexate (1.0 microng/hr/mouse; plateau plasma concentration, 2 X 10(-8) M), [3H]deoxyuridine incorporation into DNA was inhibited to a significant degree in small intestine and femur marrows. However, incorporation of [3H]thymidine into intestinal DNA was stimulated at this low infusion rate. During high infusion rates of methotrexate (10 microng/hr/mouse, plateau plasma concentration, 4 X 10(-7) M), inhibition of the incorporation of [3H]deoxyuridine at the steady state levels of plasma methotrexate in both the small intestine and femur marrow was significant. In contrast to stimulation at the low infusion rate, incorporation of [3H]thymidine into intestinal DNA at this high infusion rate was inhibited to a significant degree. Inhibition was not statistically significant in femur marrow DNA. The inhibition of [3H]thymidine into intestinal DNA could be reversed by the simultaneous infusion of inosine. Thus, in the in vivo system, an antipurine effect on DNA Synthesis at high methotrexate plasma concentration in the small intestine was observed. This antipurine effect was not apparent at the lower concentrations. The lower concentration, however, could still inhibit [3H]deoxyuridine incorporation into intestinal and femur marrow DNA to a significant enough degree that, if prolonged, it would resultin lethality to the mice. The thymineless state can be maintained for at most 60 hr in mice without lethal toxicity, whereas the antipurine state can be maintained for no longer than 18 hr in mice without some lethal toxicity. These data have important implications in rescue studies using thymidine or leucovorin.

Animals↗
PubMed1975

Purification and properties of Clostridium botulinum type F toxin.

Clostridium botulinum type F toxin of proteolytic Langeland strain was purified. Toxin in whole cultures was precipitated with (NH4)2SO4. Extract of the precipitate was successively chromatographed on diethylaminoethyl-cellulose at pH 6,0, O-(carboxymethyl) cellulose at pH 4.9, and finally diethylaminoethyl-cellulose at pH 8.1. The procedure recovered 14 percent of the toxin assayed in the starting culture. The toxin was homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, double gel diffusion serology, and isoelectric focusing. Purified toxin had a molecular weight of 150,000 by gel filtration and 155,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Specific toxicity was 9.6 X 10-6 mean lethal doses per absorbancy (278 nm) unit. Sub-units of 105,000 and 56,000 molecular weight are found when purified toxin is treated with a disulfide reducing agent and electrophoresed on sodium dodecyl sulfate-polyacrylamide gels. Reciprocal cross neutralizations were demonstrated when purified type F and E toxins were reacted with antitoxins which were obtained with immunizing toxoids prepared with purified toxins.

Ammonium Sulfate↗
PubMed1975

Growth potential of Clostridium botulinum in fresh mushrooms packaged in semipermeable plastic film.

Fresh mushrooms (Agaricus bisporus) were inoculated in the stem, gill, or cap with Clostridium botulinum spores. They were placed with uninoculated mushrooms in paper board trays, which were then covered and sealed in a polyvinyl chloride stretch film to simulate prepackaged mushrooms available at retail stores. When incubated at 20 C, botulinum toxin could be detected as early as day 3, or 4, when the mushrooms still appear edible. Mushrooms inoculated in the stem with 1,000 type A spores frequently became botulinogenic; higher spore levels were needed if gills or caps were inoculation sites. Type B spores were less apt to produce toxic mushrooms. Respiration of the fresh mushrooms used up O2 more rapidly than could enter through the semipermeable wrapping film, so that the equilibrium O2 concentration became low enough for growth of C. botulinum. Inoculated mushrooms did not become botulinogenic when held at 4 C.

Basidiomycota↗
PubMedDate not supplied

Prevention of malrotation deformity in femoral shaft fracture.

OBJECTIVE: To confirm the need to check anteversion (AV) of the intact femur to prevent malrotation deformity following intramedullary nailing in femoral shaft fracture. DESIGN: Prospective. RESULTS: Four patients out of forty-two (forty-three nailings) developed malrotation deformity of more than 15 degrees after femoral nailing. In the second part of the study, distal fragments of the fractured femurs were rotated 13.8 degrees on average to match with the rotational alignment of the intact femur. The malrotation deformity was controlled to less than 5 degrees in all cases. Closed reduction along the longitudinal axis of the femur was performed and was acceptable in forty-two cases (thirty-four cases in Part 1 of the study and eight cases in Part 2) prior to nailing. The coefficient of correlation between preoperative and postoperative AVs was 0.73 in these cases. CONCLUSION: Because true neutral rotation of the distal fragment alone is not accurate in preventing malrotation deformity of the femur following intramedullary nailing, we recommend measuring AV in both intact and fractured femurs and correcting rotational malalignment if it exists at the time of femoral nailing. Rotational alignment did not change significantly unless we failed to externally reduce the fracture due to a flexion deformity of the proximal fragment.

Femoral Fractures↗