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Biomedical subjects

G Alexander

Publications and source records attributed to G Alexander.

13 recordsLinked to original sources
PubMed1979

Hyaline membrane disease. Comparison of continuous negative pressure and nasal positive airway pressure in its treatment.

The effectiveness of continuous negative pressure (CNP) and nasal continuous positive airway pressure (CPAP) in the treatment of hyaline membrane disease and the incidence of complications were compared in 36 preterm infants randomly treated with CNP or nasal CPAP. Both methods of treatment were effective in increasing PaO2 and allowing a decrease in inspired O2 concentration. The time required with mechanical assistance and with an O2 concentration of more than 40% was equal in both groups. In the CNP group, four infants required mechanical ventilation because of clinical deterioration whereas in the nasal CPAP group, seven needed this type of therapy. Three infants in each group had extraalveolar air, and two patients in each group died. The results suggest that both methods of applying continuous distending airway pressure are effective. Nasal CPAP has the advantages of easier application and better access to the infant.

Blood Pressure↗
PubMed1979

Cold thermogenesis.

Explore the source record for details and available documents.

Adipose Tissue, Brown↗
PubMed1978

Ultrastructural development of adipose tissue in foetal sheep.

The development of subcutaneous and perirenal adipose tissue in foetal sheep of 40--150 days conceptual age was examined using electromicroscopy. Adipose tissue from both sites developed from pre-adipose cells of similar appearance, with few mitochondria, and commenced accumulating lipid on about day 70 of gestation. In the perirenal fat there was marked proliferation of mitochondria between days 80 and 90 and the tissue developed into brown fat, cell profiles being characterized by many mitochondria with numerous distinct cristae, whereas in the subcutaneous cells which developed into white adipose tissue few mitochondria with fewer cristae were observed. Multilocular and unilocular cells occurred in both tissues near term. Nerves were first seen between brown adipose cells in a 130-day-old foetus and were frequently seen in older foetuses, but very few nerves were seen in the white adipose tissue. In hypophysectomized foetuses, either full- or post-term, the subcutaneous fat and internal fat were shown to be white and brown adipose tissue respectively, as in normal foetuses, although in one 164-day-old foetus the perirenal tissue appeared to be a mixture of brown and white fat.

Adipose Tissue↗
PubMed1976

Analysis of the acidic fraction of marijuana smoke condensate by capillary gas chromatography-mass spectrometry.

A method for the analysis of organic acids and phenols isolated from marijuana smoke condensate has been developed. Comparative analyses of standard tobacoo, Mexican, and Turkish marijuana smoke condensates carried out by means of capillary gas chromatography indicated both qualitative and quantitative changes in the constituents of chromatographic profiles. Samples were converted to volatile derivatives by methylation and trimethylsilylation; whereupon, 49 aliphatic acids, aromatic acids, and phenolic compounds were identified by means of capillary gas chromatography-mass spectrometry.

Acids↗
PubMed1975

Brown adipose tissue in the new-born calf (Bos taurus).

1. Electron microscopic examinations revealed that most of the adipose tissue of new-born calves had the cellular morphology of brown adipose tissue; only subcutaneous tissue had the cellular morphology of white adipose tissue. 2. The cellular morphology of the brown adipose tissue changed progressively to that of white adipose tissue as the age of the calves increased. 3. Infusion of noradrenaline (I.V.) at rates of 1 and 5 mug/kg.min into new-born calves exposed to a thermoneutral environment increased metabolic rate two- to threefold, and also increased rectal temperature and respiration rate. The responses declined as age of calf increased. 4. Approximately 2% of the body weight of new-born calves appears to be brown adipose tissue.

Adipose Tissue↗
PubMed1975

Maximum thermogenic response to cold in relation to the proportion of brown adipose tissue and skeletal muscle in the body and to other parameters in young lambs.

No relationship was apparent between the maximum thermogenic response of lambs to cold (summit metabolism) and the dissectable brown adipose tissue content, or the chemically extractable lipid content of the whole animal or the weight of various skeletal muscles. Correlations of summit metabolism with other parameters also suggested that the level of glucose, FFA and glycerol in the circulation, and the glycogen stores in liver and muscle, did not limit summit metabolism. However, significant correlations of summit metabolism with cardiac output and arteriovenous differences in oxygen content of blood focused attention on the possible role of the cardiovascular system and on the metabolic capability of the thermogenic tissues in determining summit metabolism.

Adipose Tissue, Brown↗
PubMed1975

Quantity and calculated oxygen consumption during summit metabolism of brown adipose tissue in new-born lambs.

Macroscopic dissection of new-born lambs of several breeds revealed that brown adipose tissue comprised approximately 1.5% of the body weight. The perirenal-abdominal and prescapular-cervical depots were by far the largest, and the overall distribution was largely consistent with that reported for other species, although there was no significant interscapular depot. The oxygen consumption of the brown adipose tissue in lambs was calculated to reach 70 ml/(g-h), which is consistent with published data for rabbit brown adipose tissue, in vivo, but 35 times higher than that for the same tissue in vitro. It was also calculated that a substantial portion, perhaps two thirds, of the lipid available for metabolism was stored outside the adipose tissue. The study also made it possible to examine the validity of methods of estimating blood flow through brown adipose tissue. Untenable venous blood oxygen saturations were calculated from results obtained using 86-Rb, but saturation calculated from results with the radio-active microsphere method were entirely plausible.

Adipose Tissue, Brown↗