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Biomedical subjects

S C Chang

Publications and source records attributed to S C Chang.

At least 325 records · Page 18Linked to original sources
PubMed1985

Bacterial Alginate Produced by a Mutant of Azotobacter vinelandii.

The optimum conditions in shaken flasks for production of bacterial alginate by mutant C-14 of Azotobacter vinelandii NCIB 9068 and a comparison of the properties of bacterial and algal alginates were investigated. The largest amount of bacterial alginate was obtained in about 110 h by a culture grown on optimum medium at 34 degrees C and 170-rpm shaking speed. The viscosity of the culture broth was 18,400 cps and the alginate concentration reached 6.22 g/liter. The viscosity of the purified bacterial alginate was as high as 11,200 cps at a low concentration (0.6%). A greater than fivefold concentration of algal alginate was required to reach the same viscosity at a low shear rate. A solution of bacterial alginate was more pseudoplastic than that of algal alginate was. No significant differences were observed in other properties of bacterial and algal alginates such as gel formation with calcium ion, thermostability, and effect of temperature, pH, and sodium chloride on viscosity.

Journal Article↗
PubMed1985

Isolation and Some Properties of the Enzyme That Transforms Eremofortin C to PR Toxin.

PR toxin and eremofortin C are secondary metabolites of Penicillium roqueforti. The chemical structures of these two compounds are closely related to each other and differ only by an aldehyde and an alcohol group at the C-12 position. In an effort to better understand the biosynthesis of PR toxin, we discovered the enzyme of P. roqueforti that is responsible for the transformation of eremofortin C to PR toxin. The maximum activity of the enzyme in the culture medium was found to occur on day 13, which corresponded to the maximal production of PR toxin in the medium. The enzyme was isolated and purified from the culture medium and the mycelium of the fungus, respectively, through a procedure involving ammonium sulfate fractionation and DEAE-cellulose chromatography. The specific activity increased 20- and 8-fold, respectively, and the yield was 33.3 and 21.6%, respectively, for the enzyme from the medium and mycelium. The optimal pH for the enzyme reaction was ca. pH 5.6. The enzyme reaction was temperature dependent. The rates followed a linear time course when it catalyzed the transformation at 30 degrees C and decayed with time when reacted at higher temperatures. At 100 degrees C, the enzyme activity was completely lost. The K(m) and V(max) of the enzyme as determined at 30 degrees C were 0.02 mM and 4.0 mumol/min per mg, respectively. The molecular weight of the enzyme was estimated by gel filtration on a high-pressure liquid chromatography I-250 protein column to be ca. 40,000.

Journal Article↗
PubMed1985

Chemical transformation of eremofortin C into PR toxin.

The natural products of both eremofortin C (EC) and PR toxin are secondary metabolites of Penicillium roqueforti. Because the chemical structures of EC and PR toxin are closely related to each other and differ only by a hydroxyl functional group in EC and an aldehyde functional group in PR toxin at the C-12 position, the chemical transformation of EC into PR toxin was investigated. Oxidation with a chromic anhydride-pyridine complex was found to be the most satisfactory method.

Naphthols↗
PubMed1985

Ocular esterase composition in albino and pigmented rabbits: possible implications in ocular prodrug design and evaluation.

A methodology was developed to determine the proportion of acetyl- (AChE) and butyrylcholinesterase (BuChE) in the albino and pigmented rabbit eye. It was found that BuChE contributed over 75% of the cholinesterase activity in all the ocular tissues but the corneal epithelium of the albino rabbit. This esterase was principally responsible for the parabolic chain length dependence of ocular hydrolysis of model naphthyl ester prodrugs reported previously. In contrast, when incubated with AChE, the rate of hydrolysis of these esters decreased monotonically with increasing ester chain length. Together these findings suggest that esters whose chain length exceeds 4 carbons will be hydrolyzed primarily by BuChE. It is suggested that the dominance of BuChE in ocular tissues is another factor which merits consideration in the design and evaluation of ocular ester prodrugs.

Acetylcholinesterase↗
PubMed1984

Neurilemmoma of the vagus nerve. A case report and brief literature review.

A case of neurilemmoma of the vagus nerve is reported. The patient is alive and well 8 years following resection. The term "neurilemmoma" is the preferred nomenclature. The disease presentation, differential diagnosis, and the surgical approach is discussed. The proper treatment for this tumor is surgical removal with preservation of the vagus nerve if possible and reanastomosis and/or nerve grafting if that is not possible.

Adult↗
PubMed1983

Deep innervation of sural nerve.

Discharges of 37 sural afferents in the A alpha to C fiber range have been recorded during stimulation of subcutaneous tissues after removal of the skin. Except for one A alpha unit with muscle spindle properties, fibers were not easily excited by muscle stretching. The more slowly conducting fibers tended to have higher thresholds. After repeated stimulation, most A delta and C units displayed a persistent afterdischarge which lasted from several minutes to more than half an hour.

Achilles Tendon↗
PubMed1982

Lignocellulolytic Enzymes Produced by Volvariella volvacea, the Edible Straw Mushroom.

Volvariella volvacea, commonly known as the straw or paddy mushroom, had the following growth characteristics: minimum temperature, 25 degrees C; optimal temperature, 37 degrees C; maximal temperature, 40 degrees C; pH optimum 6.0. Optimal pH for cellulase production was 5.5. The optimal initial pH for cellulase production and mycelial growth was found to be 6.0. The pH and temperature optima for cellulolytic activity were 5.0 and 50 degrees C, respectively. Maximal cellulolytic activity was obtained within 5 days in shake-flask culture. The cellulases were found to be partly cell free and partly cell bound during growth on microcrystalline cellulose. The endoglucanase activity was primarily extracellular, and beta-glucosidase activity was found exclusively extracellularly. Weak cellulase activity was detected when cells were grown on cellobiose and lactose. V. volvacea could not digest the lignin portion of newspaper in shake-flask cultivation. Phenol oxidase, an important enzyme in lignin biodegradation, also was lacking in the cell-free filtrate. However, the organism oxidized phenolic compounds when it was cultured on agar plates containing commercial lignin.

Journal Article↗
PubMed1982

The self: a nodal issue in culture and psyche - an Eastern perspective.

The self is central in life. It is a principle by which one, consciously or not, organizes one's personality and relates to the world. The "Eastern" self is conducive to an interdependent-holistic-centripetal psychosocial orientation, the "Western" self to an independent-individualistic-centrifugal orientation. They represent a polarity of thoughts on the nature and place of man. Cultural correlates and psychological implications of the Eastern tradition are discussed.

Art↗
PubMed1981

Intranuclear inclusion bodies within neurons of spinal and cranial ganglia in three cyprinid species.

A histological examination of 205 fish representing four cyprinid species from a site 2.5 miles north of Wheeling, West Virginia, on the Ohio River revealed large (2--4 micron) cuboidal intranuclear inclusion bodies (NIB's) within neurons in the cranial and spinal ganglia of three species. Because the minnows had been caught during a yearly sampling of fish, an additional 63 minnows were taken the following year. Inclusions were again observed. The NIB's stain strongly with phloxine as well as with Mallory and Giemsa stains, appearing bright red or pink. Various histochemical tests indicated that the inclusions contain protein and lipid but no carbohydrates or nucleic acids. No heavy metals were detected by electron probe analysis. At the ultrastructural level the inclusions exhibit subunits resembling hexagons measuring 326--350 nm. Previously suggested causes for such inclusions include effects of viruses, aging, drugs, cellular transformation, and an altered metabolic state of affected cells.

Animals↗
PubMed1980

High pressure liquid chromatographic determination of aflatoxins in soy sauce and fermented soybean paste.

A procedure for the quantitative determination of aflatoxins B1, B2, G1, and G2 in soy sauce and fermented soybean paste is proposed using high pressure liquid chromatography with ultraviolet detection after CB extraction and SEP-PAK and preparative thin layer chromatographic cleanups. Recoveries of 71.3 to 89.3% were obtained for soy sauce spiked with 1, 5, 20, and 100 ppb aflatoxins. Similar recoveries (77.0 to 90.8%) were obtained with concentrated soy sauce and fermented soybean paste spiked at 20 and 100 ppb. In comparison with other procedures, the proposed procedure is relatively fast and precise and gives good recoveries. Aflatoxins were not stable in soy sauce. During storage, half of aflatoxins B1 and G1 were deteriorated at 60 and 120 days, respectively.

Aflatoxins↗
PubMed1979

A data storage and retrieval system for clinical research.

A data storage and retrieval system is presented that can be used for clinical research studies. The system is designed in such a way that the programs are independent of the application. It can be used by non-computer experts via a simple query language. Since it is bulit up in a modular way extensions can be easily made. The system is implemented on a PDP 11/70 under FORTRAN.

Computers↗