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Biomedical subjects

D G Cooper

Publications and source records attributed to D G Cooper.

At least 55 records · Page 3Linked to original sources
PubMed1982

Characterization of Nocardia amarae as a Potent Biological Coalescing Agent of Water-Oil Emulsions.

Nocardia amarae grown in a liquid medium induced coalescence of emulsions which differed in type, composition of the organic phase, and structure of stabilizing emulsifiers. De-emulsifying activity varied with the type of growth medium, culture age, and postharvest treatment. Based on extraction and degradation studies, it was concluded that de-emulsifying properties are due to the bacterial cell surface. Thus, bacteria may provide a new source of de-emulsifying agents.

Journal Article↗
PubMed1981

Surface-Active Lipids from Nocardia erythropolis Grown on Hydrocarbons.

Nocardia erythropolis (ATCC 4277) was grown in a 28-liter fermentor on mineral salts medium and 4% hydrocarbon. Extraction of the neutral lipids with pentane removed approximately 90% of the surface activity of the culture medium. The residual surface activity of the culture medium was attributed to the polar lipid fraction which was not extracted with pentane. Analysis of the pentane extracts with thin-layer chromatography showed the presence of four major compounds. A fatty alcohol reached a maximum concentration in the early log phase of growth and then decreased to the end of the fermentation. A monoglyceride, an ester, and a fatty acid appeared during the log phase of growth and continued to increase until the end of the fermentation. The fatty acids isolated from the culture grown on hexadecane had a carbon skeleton with the same length as the substrate, with 70% of the component as the saturated acid and 30% as a monounsaturated homolog. When isolated from a kerosene culture, the fatty acids consisted of a number of homologs from C(18) to C(20), including branched-chain and unsaturated acids, reflecting the distribution of the branched-chain isomers in the substrate.

Journal Article↗
PubMed1981

Enhanced Production of Surfactin from Bacillus subtilis by Continuous Product Removal and Metal Cation Additions.

The lipopeptide, surfactin, is produced by Bacillus subtilis. A study has been made on large-scale production of this surfactant. A good yield was obtained from a glucose substrate fermentation by continuously removing the product by foam fractionation. The surfactin could be easily recovered from the collapsed foam by acid precipitation. The yield was also improved by the addition of either iron or manganese salts. Hydrocarbon addition to the medium, which normally increases biosurfactant production, completely inhibited surfactin production by B. subtilis.

Journal Article↗
PubMed1980

The effect of substrate on inhibition of Corynebacterium lepus by isonicotinic acid hydrazide (Isoniazid).

Isonicotinic acid hydrazide (INH) inhibits the growth of Corynebacterium lepus on hexadecane but has no effect on its growth on fructose. INH also inhibits the production of the mycolic acid containing lipopeptide bioemulsifier normally produced by C. lepus in response to an insoluble substate. The primary effect of INH appears to be inhibition of mycolic acid synthesis, which limits the growth of C. lepus on hexadecane by reducing the concentration of bioemulsifier.

Alkanes↗
PubMed1979

Mk in three generations of an English family.

Mk was demonstrated in three generations of an English family. The propositus was detected as a result of an incompatibility in cross-match. General serological, biochemical and biophysical aspects have been studied.

ABO Blood-Group System↗
PubMed1979

Production of surface-active lipids by Corynebacterium lepus.

Corynebacterium lepus was grown in 20-liter batch fermentations with kerosene as the sole carbon source. Critical micelle concentration measurements indicated the production of appreciable quantities of biosurfactants. This surface activity of the culture medium was due to lipids, which were extracted and identified. Samples of C. lepus whole broth were taken during a fermentation and monitored for surface tension, amount of surfactant present, and lipid content. The changes in the surfactant measured correlated with concentration changes of several surface-active lipids. An early dramatic increase in surfactant concentration was attributed to the production of a mixture of corynomycolic acids (beta-hydroxy alpha-branched fatty acids). Surface activity at the end of the fermentation was due to a lipopeptide containing corynomycolic acids plus small amounts of several phospholipids and neutral lipids which were identified by thin-layer chromatography.

Amino Acids↗
PubMed1979

Analysis of corynomycolic acids and other fatty acids produced by Corynebacterium lepus grown on kerosene.

The saponifiable carboxylic acids of the extracellular product of Corynebacterium lepus grown on kerosene have been isolated and characterized. About 25% of these acids were a mixture of simple, saturated fatty acids ranging from C13 to C24 and including both even and odd homologues. The distribution of these acids was bimodal, with maxima at C15 and C21. The other 75% of the acids was a mixture of corynomycolic acids [R1--CH(OH)--CH(R2)--COOH] ranging from C28 to C43. The R1 alkyl fragments varied from C16 to C25, and R2 fragments varied from C6 to C14. Both even and odd corynomycolic acid homologues were observed, and the distribution had a single pronounced maximum at C32 and C33. Bacterial utilization of the carboxylic oxidation products of the kerosene substrate is suggested to account for the wide distribution in chain length of these saturated fatty acids and for the observation of both even and odd homologues.

Carboxylic Acids↗
PubMed1977

The pigment dispersion syndrome.

The pigment dispersion syndrome was noted in 10% of white and black subjects with and without glaucoma. This suggested pigment dispersion was not a high risk factor in the development of glaucoma. The HLA-B7 antigen was less prevalent and HLA-B13 and Bw17 antigens were significantly more prevalent in individuals with the pigment dispersion syndrome than in subjects without the syndrome. Either HLA-B13 or Bw17 antigen was found in 23 (77%) of 30 patients with the pigment dispersion syndrome and in only 13 (6%) of the 203 subjects without pigment dispersion. Pigmentary glaucoma was characterized by a significantly higher prevalence of combinations of HLA-B12 and B13 or HLA-B12 and Bw17 antigens as compared to the pigment dispersion syndrome without glaucoma, primary open-angle glaucoma, or the general population. This suggested that pigmentary glaucoma differed genetically from primary open-angle glaucoma and was a separate entity.

Glaucoma↗
PubMed1977

The ocular hypotensive effect of epinephrine in high and low corticosteroid responders.

Nonglaucomatous individuals were classified by their intraocular pressure response to 6 weeks of topical dexamethasone, 0.1%, four times daily. Twenty GG responders (over 31 mm. Hg after dexamethasone) and 20 NN responders (below 20 mm. Hg after dexamethasone) of similar age, sex, race, initial intraocular pressure, and facility of outflow were selected. After 24 hr. of treatment (two doses) with 1% epinephrine HCl, the GG subjects demonstrated a mean (+/-sigma) corrected decrease in intraocular pressure of 4.2 mm. Hg (+/- 2.5) as opposed to 1.8 mm. Hg (+/- 2.1) in the NN subjects (p less than 0.005). The relationship between increased responsiveness to corticosteroids, to epinephrine, and to theophylline suggested cyclic nucleotides as a possible common pathway.

Administration, Topical↗
PubMed1970

Primary immunization of Rh-negative volunteers.

To determine the best method for the production of high-titre anti-D serum primary immunization was carried out in two groups of Rh-negative male volunteers with washed group O R(2)R(2) cells. The first group of six men were given 5 ml. of packed cells, and the second group of five men were given 0.5 ml. of packed cells, in each instance by intravenous injection. Only one individual in each group failed to develop anti-D following the primary inoculation, and it has been concluded that 0.5 ml. of packed R(2)R(2) cells is probably a satisfactory dose for this purpose.There was a delay of several weeks before anti-D could be shown to have developed. The initial antibodies which appeared in the serum comprised 7S gammaG immunoglobulins, with, in about half the cases, a minor 19S gammaM component.

Antibody Formation↗
PubMedDate not supplied

Toluene removal in an automated cyclical bioreactor.

A control scheme was developed for the automation of toluene removal in a cyclical bioreactor. Toluene was added to the self-cycling fermentor by diffusion across a silicone membrane. Transient dissolved oxygen, carbon dioxide evolution, and oxidation-reduction potential (ORP) were screened as potential control variables. Through experimentation, ORP was deemed most effective. Control algorithms based on real-time estimates of the first and second derivatives of the ORP signal were tested. Although both approaches resulted in stable operation of the reactor, average toluene removal efficiencies of 95% were realized when control was based on the second derivative. This was significantly higher than the 77% efficiencies obtained when the control scheme centered on the first derivative of the transient ORP signal. The system developed was self-regulating, ensuring that a high toluene removal rate, on the order of 1.1 g h(-1), was maintained from cycle to cycle.

Automation↗