Biomedical subjects
Publications and source records attributed to D Barlow.
The reduction of pyruvate, 2-oxobutyrate, hydroxy-pyruvate and glyoxylate under optimal conditions at 37 degrees by extracts of human heart, kidney, pancreas, skeletal muscle and liver has been examined. The ratios of reduction rates, particularly of glyoxylate and 2-oxobutyrate reveal a capacity to differentiate the isoenzyme composition of the tissue extracts.
250 consecutive female contacts of men with gonorrhoea were examined in Lydia Department of Genito-urinary Medicine, St Thomas' Hospital, London, and 165 (66 per cent.) were found to be positive for gonorrhoea. Over 99 per cent. of the positive results were found by the first two sets of genital investigations. These results are compared with earlier and more recent results from our own and other centres and it is postulated that the higher early diagnosis rate is due to the introduction of a highly selective but non-inhibitory culture medium (VCNT), combined with a new incubator which accurately regulates temperature, humidity, and CO2 content. Reasons for the negative findings in 35 per cent. of the female gonorrhoea contacts are discussed.
1. The lactate dehydrogenase activity of 89 sera from patients suffering myocardial infarction and of 55 sera from patients with hepatocellular damage was assayed under optimal conditions using pyruvate, alpha-oxobutyrate, hydroxypyruvate and glyoxylate as substrates. Activity was also measured with lactate as substrate at different pH values. 2. The ratios of activities under these different assay conditions were calculated for both series of patients. Correct differentiations for single ratios ranged from virtually nil for hydroxypyruvate/alpha-oxobutyrate to is greater than 93 per cent for glyoxylate/hydroxypyruvate and glyoxylate/alpha-oxobutyrate. This was little improved by the use of multiple ratios involving up to seven separate assays. 3. The activity ratio of hydroxypyruvate to pyruvate which is consistently greater than unity was found to be inverted in a case of morphine poisoning.
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The alpha-helix defined in 1951 by Pauling et al. on the basis of model building and X-ray fibre diffraction data has 3.65 residues per turn (n) achieved with planar peptides, torsion angles of phi = -48 degrees and psi = -57 degrees and hydrogen bonds which are close to linear. Although X-ray analyses of proteins have confirmed the general correctness of the model for the helix, recent high resolution (1.7-1.0 A) diffraction studies have shown that the parameters described by Pauling et al. and later by Perutz and Arnott and Wonacott are not a good description of the alpha-helices in globular proteins, where the mean values of phi, psi are usually close to -63 degrees, -42 degrees. Here we show that these values arise as a mean of two significantly different classes in amphipathic helices depending on whether the peptide carbonyl oxygen is hydrogen bonded to a solvent or polar side-chain atom. The hydrogen bonds made by the hydrophilic carbonyls to the NH groups within helices are longer and less linear than those involving hydrophobic carbonyls. We also show that these effects are associated with a significant curvature of helices in globular proteins. For example, the alpha-helix in avian pancreatic peptide (aPP) has a radius of curvature of approximately 70 A. These results are of significance in the packing of helices in fibrous and globular proteins, in the calculation of their dipole moments, solvent accessibilities and internal energies, and in the theoretical estimation of spectroscopic properties such as circular dichroism and Raman scattering.
Tinea capitis is regarded as rare in healthy adults. A study of 46 adults presenting with scalp problems with no other identifiable cause and 26 asymptomatic adult contacts of children with tinea capitis was undertaken. The confirmation of tinea capitis in 9 of 46 patients and 5 carriers among 26 adult contacts suggests that tinea capitis may affect healthy adults more often than was supposed. Further epidemiologic studies may be of interest.
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