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D Rees

Publications and source records attributed to D Rees.

105 records · Page 6Linked to original sources
PubMed1974

Effect of acute and chronic calcium administration on plasma renin.

To evaluate the effect of Ca(++) on renin release, plasma renin activity (PRA) was measured after acute and chronic Ca(++) administration. 1% CaCl(2) was infused into one renal artery of 10 anesthetized dogs (0.3 mg/kg/min). The excreted fraction of filtered calcium (EF(ca++)) and EF(Na+) from the infused kidney were elevated (P < 0.04) during three successive 15-min infusion periods. Serum calcium concentration was significantly elevated (P < 0.001). Creatinine clearance, systemic arterial pressure, and renal blood flow did not change (P > 0.10). Compared to control (45 ng/ml/h+/-5.2 SE), renal venous PRA was suppressed (P < 0.0001) after infusion of Ca(++) for 15, 30, and 45 min (20 ng/ml/h+/-4.6, 16 ng/ml/h+/-4.0, and 13 ng/ml/h+/-2.7, respectively). 15 and 30-min after infusion, PRA did not differ from control (P > 0.20). Chronic Ca(++) loading was achieved in Sprague-Dawley rats by replacing drinking water with 1% CaCl(2) for 17 days. At sacrifice, serum Ca(++), Na(+), and K(+) of controls (n = 12) did not differ (P > 0.60) from Ca(++)-loaded rats (n = 12). Ca(++) excretion (467 mueq/24 h+/-51) was elevated (P < 0.001) compared to controls (85 mueq/24 h+/-12). PRA (8.6 ng/ml/h+/-1.4) and renal renin content of Ca(++)-loaded rats did not differ from controls (P > 0.80). However, after 8 days of sodium deprivation, both PRA and renal renin content of calcium-loaded animals were significantly lower than the respective values in pair-fed controls (P < 0.005). During the period of sodium deprivation, calcium-drinking animals were in greater negative sodium balance than controls (P < 0.005). The data are consistent with the hypothesis that acute and chronic calcium administration inhibit renin secretion.

Animals↗
PubMedDate not supplied

Fragile X mental retardation and the iduronate sulphatase locus: testing Laird's model of fra(X) inheritance.

Fragile X [fra(X)] mental retardation syndrome is the most frequent familial cause of mental handicap. The clinical phenotype is associated with a rare fragile site at Xq27.3. The mutation underlying the disorder, an insertion into the FMR-1 gene, has been characterized, but the pathogenesis of the condition is obscure and the pattern of inheritance is still not fully understood. One model of fra(X) pathogenesis was proposed by Laird in 1987, suggesting that the fra(X) mutation acts as a cis-acting, local block to the pre-oogenesis reactivation of the inactivated X chromosome. To test this model, we examined the activity of the F8, F9 and iduronate sulphatase (IDS) loci. The level of IDS in the serum of fra(X) males was found to be very significantly reduced in the fra(X) group when compared to that of control males: this lends support to Laird's model of fra(X) pathogenesis. However, we detected no methylation differences between fra(X) and control samples at the IDS locus, although such changes are known in fra(X) males at sites closer to the fragile site. Thus the mechanism of the reduction in IDS activity has not been identified.

DNA↗
PubMedDate not supplied

Occupational health indicators for South Africa.

Indicators, statistics gathered from a larger pool because they have the power to summarize or to serve as indirect or proxy measures for information that is lacking, would be valuable in appraising occupational health status in a country provided data are both feasible and relatively inexpensive to collect. A generally accepted set of occupational health indicators does not exist. This project aimed to compile a set for South Africa. An initial set of possible indicators was compiled and then rated by key informants. A committee of the National Centre for Occupational Health selected a final set of 16 indicators. The indicators and limited data collected on some of them are presented with commentary. The validity and the impact of the indicators need to be formally assessed.

Accidents, Occupational↗
PubMedDate not supplied

Silicosis and tuberculosis: a proposed radiographic classification of tuberculosis to accompany the ILO international classification of radiographs of pneumoconioses.

A significant proportion of workers exposed to silica dust are at risk of developing tuberculosis (TB). The higher the International Labor Organization (ILO) category of silicosis, the greater the TB risk. Subtle radiographic presentations of TB may be the initial manifestation of TB, particularly in the absence of sputum identification of TB bacilli. A proposed TB x-ray-reading form in addition to the ILO categorization of silicosis is offered. The implementation of a standardized TB x-ray-reading approach should alert the clinician to indolent TB lesions.

Disease Notification↗
PubMedDate not supplied

Skn antigens: identification of a 95-kilodalton protein in mouse neural tissue.

Skn alloantigens represent a tissue-specific histoincompatibility system based on their expression in epidermal cells and absence in hematopoietic tissue. Radiation chimeras produced by lethally irradiating C57BL/6 mice and reconstituting them with (C57BL/6xA/J)F1 spleen cells reject skin from A/J (A) or (B6xA)F1 donors. The studies reported here were designed to determine the expression of the Skn 2.1 alloantigen on neural tissue given the common ectodermal origin of epidermal and neuronal cells. Using a monoclonal antibody specific for the Skn 2.1 alloantigen, a protein of 95 kilodaltons was identified in brain cells of A mice and, by immunohistochemical staining, Skn 2.1 was found in neurons in the brain. Although the antigen was detected in the cerebral cortex, cerebellum, and hippocampus of the brain, the staining of cells within these regions was not uniform. Because there is a restricted pattern of Skn 2.1 expression, limited to cells of ectodermal lineage, it is hypothesized that Skn may play a role in the differentiation of ectodermally-derived tissues.

Animals↗