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Biomedical subjects

D White

Publications and source records attributed to D White.

At least 397 records · Page 22Linked to original sources
PubMed1978

Light-stimulated morphogenesis in the fruiting myxobacterium Stigmatella aurantiaca.

When the fruiting myxobacterium Stigmatella aurantiaca, a gliding prokaryote, is starved on an agar surface, the cells form multicellular aggregates resulting from morphogenetic movements. In the presence of incandescent light, each aggregate develops into a structurally complex fruiting body, possessing a stalk and several sporangia. In contrast, this pattern of development is not seen when cultures are incubated in the dark. The cells form irregular interconnecting aggregates, which rarely develop into fruits. However, aggregates formed in the light will develop into fruits even if placed in the dark, suggesting that the light produced a relatively stable alteration in the phenotype of the cells.

Light↗
PubMed1978

Peptide formation in the prebiotic era: thermal condensation of glycine in fluctuating clay environments.

As geologically relevant models of prebiotic environments, systems consisting of clay, water, and amino acids were subjected to cyclic variations in temperature and water content. Fluctuations of both variables produced longer oligopeptides in higher yields than were produced by temperature fluctuations alone. The results suggest that fluctuating environments provided a favorable geological setting in which the rate and extent of chemical evolution would have been determined by the number and frequency of cycles.

Bentonite↗
PubMed1978

Control of intermittent positive pressure breathing (IPPB) by extracorporeal removal of carbon dioxide.

Five lambs were anaesthetized, paralysed, mechanically ventilated and connected to a membrane "lung" to permit removal of carbon dioxide. When part of the carbon dioxide was removed in this manner, the tidal volume was decreased to keep PaCO2 constant. For example, when 70% of carbon dioxide was removed by the membrane lung, total ventilation was reduced by 50%, peak inspiratory pressure was decreased by 45%, and PaO2 was kept constant by increasing the inspired oxygen fraction from 0.21 to 0.27%. The removal of carbon dioxide by a membrane during positive pressure breathing could decrease barotrauma, particularly in poorly compliant lungs. Technically, the extracorporeal removal of carbon dioxide is relatively simple procedure.

Animals↗
PubMed1978

Pituitary-gonadal function in XYY and XXY men identified in a population survey.

Evidence on pituitary-gonadal function in XYY subjects has been inconclusive and based, for the most part, on selected samples such as institutionalized individuals or subjects examined for particular behavioural or medical characteristics. We report the results of a double-blind hormonal study of a sample from an entire well-defined birth cohort of men. The starting population included all males born in Copenhagen during the period 1944-1947 comprising 31,436 individuals. Chromosome determinations conducted on 4139 men representing the top 15.9% of the height distribution of the sample identified 12 XYY and 16 XXY men. All the XYY subjects and 14 XXYs consented to participate in an individual case study and were individually matched to XY controls selected from the total sample. The XYY men had significantly higher plasma concentrations of LH, FSH and testosterone than matched XY controls. There were no differences in testicular size and in the reported number of children between the XYYs and control group. XXY men from the same population showed significantly higher LH and FSH, lower concentrations of testosterone, had smaller testes and reported fewer children than their matched controls.

Adult↗