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Biomedical subjects

R B Walker

Publications and source records attributed to R B Walker.

At least 55 records · Page 3Linked to original sources
PubMed1980

A survey of intestinal parasites in rural children.

A study was undertaken to determine the prevalence of intestinal parasites in a group of rural, economically disadvantaged children. Thirty-four percent of 108 children were found to have a clinically significant parasite. The most common organism was Giardia lamblia (22 percent). Those children with Giardia were significantly (P = .05) smaller than those with negative stool examinations. Even in areas with a low overall prevalence of intestinal parasites, certain high-risk groups may have significant levels of infection.

Ascaris↗
PubMed1979

Rubella seroconversion following immunization in a rural practice.

One hundred two consecutive patients with verifiable immunization to rubella were studied in a rural West Virginia county. Hemagglutination Inhibiting (HI) antibody titres, age at immunization, and elapsed time since immunization were recorded. Twenty-three (22.5 percent) had HI titres less than 1:8. There was no statistically significant difference in whether immunization at less than 15 months or more than 15 months of age resulted in a titre of greater than or equal to 1:8. There was no evident change in group proportion of seroconversion with time; either the child initially had a seroconversion with immunization, or he/she did not. A relatively large number of children with verified immunization to rubella do not have a titre currently considered protective to rubella. This does not seem to vary with time since immunization or age at immunization.

Adolescent↗
PubMed1978

tert-Butoxycarbanyl as a convenient protecting group in synthesis of potential centrally active dopamine derivatives.

Several pivaloyl and pivaloyloxy esters and amides of dopamine were synthesized for possible antiparkinson activity. The compounds were synthesized by select O- and N-acylation and N-methylation procedures. The tert-butoxycarbonyl function is an effective and easily removed nitrogen-protecting group for dopamine. Preliminary biological testing results showed that all compounds tested elicited a hypothermic response in mice, while only O,O-dipivaloyl-N,N-dimethyldopamine reversed reserpine-induced motor depression in mice. However, it is difficult to conclude from the preliminary data that the observed biological effects were due to central dopaminergic receptor stimulation.

Animals↗
PubMed1978

The structure of propranolol hemisuccinate.

1-(N-hemisuccinyl-N-isopropylamino)-3-(1-naphthoxy)-2-propranolol, contaminated with a small amount of the N,O-dihemisuccinyl derivative, is formed when propranolol [1-isopropylamino-3-(1-naphthoxy)-2-propranolol] is allowed to react with succinic anhydride (pyridine, 70 degrees C, 5 hours). This conjugate, used by others for the preparation of an immunogen of propranolol for development of radioimmunoassay methodology for its sensitive quantitation, was previously assigned the O-hemisuccinate structure. The amide structure is assigned on the basis of comparison of infrared and nuclear magnetic resonance spectral data obtained on the product of succinylation of propranolol with data from the model compounds O-acetylpropranolol, N-acetylpropranolol and N,O-diacetylpropranolol.

Acylation↗
PubMed1976

Patterns of food iron absorption in iron-deficient white and indian subjects and in venesected haemochromatotic patients.

The absorption of radioactive iron from a solution of ferrous ascorbate, and from a standard meal containing intrinsically labelled haemoglobin and wheat, was measured in 12 Indian housewives, 18 white hospital patients and 12 subjects with idiopathic haemochromatosis. Eight of the latter had been fully treated by multiple venesections, so that their serum ferritin concentrations were below 25 mug/1. Since the serum ferritin concentrations of the housewives and the hospital patients were comparable, their body iron stores were considered to be depleted to a similar degree. There were no significant differences between the absorptions of ferrous ascorbate or of the haem iron in the standard meal by each group, but the housewives and the hospital patients absorbed significantly less of the non-haem food iron. The mean non-haem food iron absorptions were 36.4%, 5.8% and 18.9% for the treated haemochromatotic subjects, the Indian housewives and the white hospital patients respectively. The discrepancies between the absorptions of the different forms of food iron were highlighted by calculating the ratios between them. The mean non-haem: haem food iron absorption ratio for the group of treated haemochromatotic subjects was 0.98, and for the Indian housewives only 0.18. The white hospital patients did not form a homogenous population: the ratios of the five males and three of the females were greater than 1.0, whereas those of the remaining 10 females were less than 0.5. The results of this study suggest that mal-absorption of non-haem iron from a meal containing bread, presumably due to a defect at the luminal level, may be an important factor in the pathogenesis of iron deficiency in some subjects. The abnormality appears to be particularly prevalent among Indian women living in Durban.

Adolescent↗
PubMed1975

Studies on the fortification of cane sugar with iron and ascorbic acid.

1. The feasibility of improving iron nutrition by fortifying cane sugar with Fe and ascorbic acid was studied. 2. It was found to be possible to add a number of Fe salts together with ascorbic acid to sugar without affecting its appearance or storage properties. 3. The absorption of Fe from fortified sugar eaten with maize-meal porridge or made into jam or biscuits was measured in ninety-four volunteer multiparous Indian women using the 59-Fe erythrocyte utlization method. 4. The absorption of Fe from sugar fortified with ascorbic acid and ferrous sulphate and eaten with maize-meal porridge was increased about twofold in the ratio, ascorbic acid:Fe was 10:1 by weight. If the ratio was increased to 20:2, Fe absorption was increased a further threefold. 5. Sugar fortified with soluble Fe salts, including FeSO4.7H2O, discoloured both tea and coffee; sugar fortified with ferric orthophosphate did not have this effect. 6. Fe from FePO4.H2O was poorly absorbed when added with sugar to maize-meal porridge, and also when added with adequate quantities of ascorbic acid. This form of Fe was absorbed much less well than was the intrinsic Fe present in the maize. 7. When sugar fortified with FePO4.H2O and ascorbic acid was added to maize-meal porridge before cooling or was made into jam there was a several-fold increase in the amount of Fe absorbed.

Adult↗
PubMed1975

The effect of tea on iron absorption.

The effect of tea on iron absorption was studied in human volunteers. Absorption from solutions of FeCl3 and FeSO4, bread, a meal of rice with potato and onion soup, and uncooked haemoglobin was inhibited whether ascorbic acid was present or not. No inhibition was noted if the haemoglobin was cooked. The effect on the absorption of non-haem iron was ascribed to the formation of insoluble iron tannate complexes. Drinking tannin-containing beverages such as tea with meals may contribute to the pathogenesis of iron deficiency if the diet consists largely of vegetable foodstuffs.

Adult↗
PubMed1969

Magnesium nutrition of two species of sunflower.

Helianthus annuus L., the common cultivated sunflower, and Helianthus bolanderi Gray subspecies exilis Heiser, a form endemic on serpentine soils, were grown in culture solutions with widely varying Mg levels. For comparable development, H. bolanderi exilis required higher levels of Mg in the solution than H. annuus, both in the range of visual deficiency symptoms and in higher ranges.With 0.5 mm Ca in the solutions, H. annuus reached a plateau in yield in the range of 0.25 to 2.0 mm Mg in the solution, then declined in weight markedly as Mg was increased further. This decline was probably caused by the marked "luxury" consumption of Mg. Conversely, H. bolanderi exilis increased steadily in yield as Mg was raised up to 10 mm and tolerated up to 50 mm Mg in the solution with only about 30% decline in yield. The increasing yield of H. bolanderi exilis in solutions of increasing Mg level is attributable to the steadily rising Mg content of the plants. A high level of external Mg is apparently needed to bring internal Mg to the sufficiency range. This characteristic of the species also serves to obviate luxury consumption of Mg, thus contributing to its tolerance of very high external levels of this ion.

Journal Article↗