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H Arthur

Publications and source records attributed to H Arthur.

31 records · Page 2Linked to original sources
PubMed1988

A pilot trial of plasma infusions in Duchenne muscular dystrophy.

It has been proposed that a defect in tocopherol transport may lead to a chronic vitamin deficiency in Duchenne muscular dystrophy (DMD). To test this hypothesis, a pilot clinical trial which involved the infusion of tocopherol-laden plasma was carried out. An increased uptake of tocopherol into erythrocyte membranes during infusions failed to produce a significant reduction in plasma enzyme levels or to arrest the dystrophic process in the two children examined. Further studies to investigate treatments with increased amounts of tocopherol, in conjunction with other antioxidants, may prove a more fruitful avenue of research.

Adolescent↗
PubMed1983

Thermodynamic behaviour of membrane enzymes in Duchenne muscular dystrophy.

Erythrocyte ghost preparations have been prepared from blood of Duchenne patients (DMD), female carriers of the disease and controls. Arrhenius plots of Na+, K+-ATPase activity of these membrane preparations show a biphasic response for controls. For 75% of DMD and carriers the response is monophasic. This is not an inherent property of the membrane since it can vary over time in the one individual and it can be induced in normal membranes by preincubation with DMD plasma. Arrhenius plots of AChE activity showed no such difference between the three sources of blood.

Acetylcholinesterase↗
PubMed1983

Plasma lipoproteins in Duchenne muscular dystrophy.

Plasma lipoproteins of Duchenne muscular dystrophy patients and carriers of the disease, together with age- and sex-matched controls, were examined by density gradient ultracentrifugation and agarose gel electrophoresis. Analysis of density gradient profiles revealed a significant reduction in absorbance (435 nm) by low density and high density lipoproteins from Duchenne patients when compared with controls. Although no abnormalities were observed on electrophoresis of whole plasma samples, the isolated low density lipoprotein fractions from Duchenne patients and carriers displayed increased electrophoretic mobility compared with controls. The results obtained implicate the plasma lipoproteins, in particular the low density lipoproteins, as the primary site of the lesion in this disease.

Adolescent↗
PubMed1980

Biochemical correlations among the thermophilic enteric yeasts Torulopsis bovina, Torulopsis pintolopesii, Saccharomyces telluris, and Candida slooffii.

Spontaneous and drug-induced respiration-deficient mutants were isolated from the thermophilic enteric yeasts Torulopsis bovina and Saccharomyces telluris. The biochemical properties of these yeasts were compared with those of the two naturally occurring respiration-deficient thermophilic yeasts T. pintolopesii and Candida slooffii. Succinate dehydrogenase was not detected in mitochondrial fractions from C. slooffii, but was present in all other species. Cytochrome c oxidase, succinate oxidase, and reduced nicotinamide adenine dinucleotide oxidase were not detected in C. slooffii, T. pintolopesii, and the respiration-deficient mutants. Low-temperature cytochrome spectra revealed the presence of cytochromes aa3, b, c1, and c in T. bovina and S. telluris; cytochromes b, c1, and c in C. slooffii and T. pintolopesii; and cytochromes c1 and c in the spontaneous respiration-deficient mutants. Palmitoleic and oleic acids were the major fatty acids in all the species. It was noteworthy that T. pintolopesii was rich in lauric and myristic acids. CsCl equilibrium centrifugation experiments showed the presence in all the yeasts of a light-buoyant-density (1.6785 to 1.6837-g/cm3) deoxyribonucleic acid band which was identified as mitochondrial deoxyribonucleic acid by its selective elimination on treatment of cells with ethidium bromide. The latter result indicated that the spontaneous respiration-deficient mutants were similar to cytoplasmic petite mutants of S. cerevisiae. Although classical assimilation and fermentation tests indicated that the spontaneous respiration-deficient mutants were strains of T. pintolopesii, it was concluded, on the basis of marked physiological and biochemical differences, that this was not the case.

Candida↗
PubMed1977

Cell surface topography of Candida and Leucosporidium yeasts as revealed by scanning electron microscopy.

The cell surface topography of the following yeast strains was examined by scanning electron microscopy: Candida slooffii, C. lipolytica, Leucosporidium frigidum, and L. nivalis. Multipolar and lateral budding were observed in the Candida yeasts in contrast to bipolar budding in the Leucosporidium species. The cell surface topography and the morphology of the bud and birth scars in these yeasts differed markedly. Apart from the bud and birth scars, the cells of C. slooffii showed a relatively smooth topography. The bud scars were seen as a circular ridge of wall material surrounding a markedly convex scar plug. Birth scars were raised, rounded structures, which appeared to distend upon cell growth. In contrast, bud scars of C. lipolytica were platelike, lacked a distinct annulus of wall material, and were much less protuberent than those of C. slooffii. Birth scars were a more permanent feature of these cells. The topography of Leucosporidium yeasts was characterized by the presence of numerous protrusions on the cell surface. In some cases, the entire cell surface was covered by these protrusions. There appeared to be some correlations between the age of the cell and the extent of surface protrusions and degree of surface convolution...

Candida↗
PubMed1977

Women in distress.

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Alcoholics Anonymous↗
PubMed1976

Leucosporidium yeasts: obligate psychrophiles which alter membrane-lipid and cytochrome composition with temperature.

The temperature limits of growth of three psychorphilic yeasts, Leucosporidium frigidum, L. gelidum and L. nivalis, were examined. All species grew well as subzero temperatures (-I degrees C). The maximum temperature of growth was significantly higher with glucose as substrate (18 to 20 degrees C) than with ethanol (17 to 18 degrees C). There was a positive correlation between the growth temperature and the degree of fatty-acid unsaturation of the cell lipids; the lower the temperature, the greater the degree of fatty-acid unsaturation. At subzero temperatures (-I degrees C) with ethanol as substrate, 90% of the total fatty acid was unsaturated with linolenic (35 to 50%) and linoleic (25 to 30%) acids predominating. At temperatures close to the maximum for growth, linolenic acid accounted for less than 20% of the total fatty acid and oleic (20 to 40%) and linoleic (30 to 50%) acids were the major components. Difference spectra of intact cells showed marked changes in the rations and amounts of individual cytochromes as a function of growth temperature. In L.frigidum with glucose as substrate, the ratios of cytochromes a +a3:b:c at 8 and 19 degrees C were I:I-I:2-9 and I:2-3:16-7 respectively. Similar changes in cytochrome ratios were noted for L.gelidum, but changes were much less marked for L. nivalis. The temperature effects were interpreted as supporting the view that membrane structure and composition are fundamental to temperature adaptation in psychrophilic yeasts.

Basidiomycota↗
PubMed1976

Thermal adaptation in yeast: growth temperatures, membrane lipid, and cytochrome composition of psychrophilic, mesophilic, and thermophilic yeasts.

The temperature limits of growth of a number of yeast species were examined, and on this basis the organisms were classified into different thermal categories. The following species were examined: Leucosporidium frigidum and Leucosporidium nivalis, psychrophilic, temperature limits of growth, -2 to 20 degrees C; Canadian lipolytica mesophilic, temperature limits of growth, 5 to 35 degrees Candida parapsilosis and Saccharomyces telluris, thermotolerant, temperature limits of growth, 8 to 42 degrees C; Torulopsis bovina and Candida slooffi, thermophilic, temperature limits of growth, 25 to 45 degrees C and 28 to 45 degrees C, respectively. The membrane lipid and cytochrome composition of mitochrondrial fractions isolated from these yeasts were compared. There was a direct correlation between the growth temperature and the degree of membrane of lipid unsaturation; the lower the temperature, the greater the degree of lipid unsaturation. The membrane lipid composition of the thermophilic yeasts were distinguished by the high percentage (30 to 40%) of saturated fatty acid, as compared with the mesophilic and psychrophilic yeasts. The latter contained approximately 90% unsaturated fatty acid, 55% of which was linolenic acid, C alpha-18:3. Changes in phospholipid composition in relation to temperature were also noted. The respiratory-deficient thermophile, C. slooffi, was characterized by the absence of cardiolipin (sensitivity 0.1 mug of phosphorus) and cytochrome aa3. The absence of conventional mitochondrial structures in this thermophilic microorganism is tentatively suggested although low concentrations of cytochromes b, c, and c1 were detected by low-temperature spectroscopy. On the other hand, the respiratory-competent thermophile, T. bovina, was characterized by a high cardiolipin (25% of the total phospholipid) and cytochrome aa3 content (1 nmol/mg of mitochrondrial protein). Low-temperature spectra showed the presence of one b-type cytochrome in the thermophilic yeasts, two b-type cytochromes in the mesophilic yeasts, and three b-type cytochromes in the psychrophilic yeasts. It was concluded that a knowledge of the properties of the biological membrane is fundamental to an understanding of the ability of a microorganism to grow and reproduce in different temperature environments.

Adaptation, Physiological↗
PubMed1971

Human relationships.

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Interpersonal Relations↗