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Biomedical subjects

P J Becker

Publications and source records attributed to P J Becker.

At least 19 recordsLinked to original sources
PubMed1992

The effect of blood sample aging and food consumption on plasma total homocysteine levels.

The stability of homocysteine in whole blood and plasma was investigated. Total homocysteine concentrations in whole blood increased rapidly to values in excess of 180% of the basal concentration if whole blood was left at ambient temperature. Sodium fluoride partially inhibited homocysteine accumulation, while refrigeration inhibited homocysteine accumulation for at least 4 h. Since intracellular concentrations of homocysteine were low, the results indicate continued metabolism of L-methionine to homocysteine after the blood sample had been obtained. In contrast to whole blood, homocysteine was stable in plasma, even at room temperature. Food consumption (normal breakfast) resulted in significantly lower plasma homocysteine concentrations, which returned to pre-prandial concentrations 8 h later. The results indicate that both blood sampling and food intake should be rigorously standardized in epidemiological studies to elucidate the possible role of elevated circulating homocysteine concentrations in premature vascular disease.

Adult↗
PubMed1992

The effect of ethnic group on appendicular bone mass in children.

The prevalence of senile and postmenopausal osteoporotic fractures is considerably higher in white than black women. Although the reasons for the genetic difference have not been elucidated, it has been suggested that ethnic differences in peak bone mass may be partially responsible. The present study examined appendicular bone mass (single-photon absorptiometry, SPA) in black and white children between the ages of 6 and 20 years. The sample was stratified for ethnic group, age, and sex. The effect of weight, height, puberty, and skinfold thickness on bone mass was also assessed. The bone width (BW) and bone mineral content (BMC) of males were significantly higher than those of females (p less than 0.0001). There were no statistically significant differences in bone mineral content normalized for bone width (BMC/BW) between the sexes (p = 0.1743 for whites and p = 0.5456 for blacks). The bone mass parameters of black girls were generally lower than those of white girls. After adjusting for height, BMC and BMC/BW of black girls tended to be greater than those of white girls (unadjusted p = 0.0258 for BMC and p = 0.0340 for BMC/BW). White boys tended to have greater bone mass parameters than black boys. After adjusting for height the trends disappeared. Thus, unlike the studies of bone mass in adults from the United States, we were unable to show that age-matched black children have higher bone mass than whites. After adjusting for height, however, the bone mass of black children (especially black girls) was marginally, but not significantly, greater than that of white girls.

Adolescent↗
PubMed1992

The value of radiographic predictors of the rate of mandibular residual ridge resorption.

This study tested the relationships between the rate of mandibular residual ridge resorption and the following two variables: cortical thickness at the gonion, and the proportion of cortical bone at the symphysis. These parameters were also compared between men and women. Measurements of cortical thickness at the gonion on panoramic radiographs were compared with similar measurements on lateral cephalometric radiographs. The results showed that neither cortical thickness at the gonion nor the proportion of cortical bone at the symphysis could be used as radiographic predictors of the rate of mandibular bone resorption. The rate of resorption was significantly greater in men than in women, while cortical thickness at the gonion in women was significantly less than that in men. Furthermore, the authors concluded that cephalometric and panoramic measurements should not be used interchangeably.

Adult↗
PubMed1992

Serum keratan sulfate levels in marathon runners.

The effect of strenuous joint loading on the metabolism of articular cartilage in man is not known. The development of a non-invasive immunoassay for the assessment of the catabolism of cartilage aggrecan has enabled us to quantify keratan sulfate (KS), a component of aggrecan, in the serum of fifteen male marathon runners. Serum KS was measured by an ELISA before and immediately after a marathon (42 km), as well as 48 hours after the completion of the race. The mean level at rest was similar to those previously reported for another population of age-matched males. There was no statistically significant difference in the serum level of KS at the three different readings. Further, there was no correlation between age, height, weight and performance time, and the serum level of KS at any of the three different times. We conclude that marathon running by carefully trained runners causes neither a transient nor a sustained increase in proteoglycan catabolism in articular cartilage.

Adult↗
PubMed1992

The comparison of the effects of multi and single doses of buspirone, chlordiazepoxide and hydroxyzine on psychomotor function and EEG.

This study compares the effects of buspirone (5 mg), chlordiazepoxide (5 mg), hydroxyzine (10 mg) and placebo on psychomotor function and EEG, when taken thrice daily for a period of two weeks, with those after a single dose administration. Nine healthy volunteers participated in the study. The battery of psychomotor tests included peak velocity of saccadic eye movements (SEM), a Sternberg memory scanning and choice reaction time test (SMS-CRT) and critical flicker fusion frequency (CFFF). The peak velocity of saccadic eye movements was significantly impaired by the single dose of hydroxyzine (P = 0.03) in comparison to the multidose results. A similar comparison regarding buspirone only approached significance (P = 0.07). The SMS-CRT and CFFF did not reveal any difference between the multi and single dose regimens. Spectral analysis of the EEG did not distinguish between the multi and single dosage schedules regarding the respective drugs in the low doses administered.

Adult↗
PubMed1992

Dust exposure and pneumoconiosis in a South African pottery. 2. Pneumoconiosis and factors influencing reading of radiological opacities.

A cross sectional radiological survey of workers exposed to pottery dust during the manufacture of wall tiles and bathroom fittings was conducted in a South African factory. Roughly one third of workers with 15 or more years of service in high dust sections of the factory had pneumoconiosis. Previously undiagnosed advanced cases, including two with progressive massive fibrosis, were working in dusty occupations. A firm diagnosis of potters' pneumoconiosis was made in 11 of the 358 workers radiographed; all had served more than 10 years suggesting that radiography of workers with more than 10 years service would be a successful case finding strategy in South Africa. A combination of rounded and irregular opacities was the most common radiological finding in the workers with pneumoconiosis (55%). Three readers reported on the chest radiographs, and all found an association between small radiological opacities, which were usually irregular or a combination of irregular and rounded, and exposure to pottery dust. The occurrence of irregular radiological opacities in workers exposed to pottery dust deserves further study. The least experienced reader significantly associated age with small opacities when duration of service (years) was used to measure exposure to dust. Sex was not an important predictor of radiological changes consistent with pneumoconiosis. Breast shadows were not an important cause of false positive readings and participating women did not develop pneumoconiosis after less exposure than men.

Humans↗
PubMed1992

A novel study on the effect of acetylsalicylic acid on the binding capacity of estrogen receptors from MCF-7 cells.

The effect of acetylsalicylic acid (ASA, aspirin) was investigated on [3H]-estradiol-17 beta ([3H]-E2) binding to estrogen receptors (ER) from MCF-7 mammary tumour cells. No effect was observed using the monoclonal estrogen receptor-enzyme immunoassay (ER-EIA). In contrast to the ER-EIA, the radioreceptor assay (RRA) showed decreases of [3H]-E2 specific binding in the presence of increasing amounts of ASA. It is therefore concluded that these results demonstrate that ASA possibly affects the direct binding of E2 to region E of the ER of human breast cancer MCF-7 cells, but does not affect binding of monoclonal antibodies to regions D and F of the ER.

Antibodies, Monoclonal↗
PubMed1992

Using changes in attributable risk to predict long-term efficacy of simvastatin treatment.

It is a common perception that coronary heart disease (CHD) deaths will decline by 2% for every 1% decrease in serum total cholesterol (TC). We investigated the changes in serum TC concentrations obtained with simvastatin, an inhibitor of hydroxymethylglutaryl-CoA reductase, in 70 hypercholesterolemic subjects. Although simvastatin reduced serum TC concentrations by 30% after 6 months, calculations from age- and risk-related TC quintiles show that the absolute difference in attributable CHD deaths would be just > 1%. These results are reminiscent of the experience from several large prospective primary drug trials that demonstrated impressive relative benefit ratios but much smaller absolute differences (< 2%) in CHD endpoints between the treated and untreated groups. This epidemiologically based approach of assessing efficacy and potential long-term benefit of a lipid-lowering drug may be more appropriate and potentially less misleading than just the percentage change of TC (or other lipoproteins) so frequently reported in short-term drug trials.

Adult↗
PubMed1992

The effect of hypovolaemia on healing of the right and the left colon. An experimental study.

An experimental study was carried out to investigate the effect of a period of hypovolaemia prior to surgery on healing of the right and left colon of the baboon. Colonic healing was assessed in three ways: in terms of (i) anastomotic leakage, (ii) hydroxyproline concentrations and (iii) breaking strength. The results suggest that hypovolaemia before surgery affects the right and left colon similarly.

Anastomosis, Surgical↗
PubMed1992

Transfer of DDT used in malaria control to infants via breast milk.

The transfer of p,p'-DDT (1,1,1-tricholoro-2,2-bis(4-chlorophenyl)ethane) and its metabolites to infants via breast-feeding was studied in an area of KwaZulu, South Africa, where DDT is used to interrupt malaria transmission. Samples of whole blood were collected from 23 infants, together with samples of breast milk from their respective mothers. The mean sigma DDT (total DDT) in the whole blood was 127.03 micrograms.l-1 and that in the breast milk, 15.06 mg.kg-1 (milk fat). The % DDT (% DDT of sigma DDT) was significantly higher in the infant blood than in the breast milk (P less than 0.05). A multiplicative regression analysis indicated that sigma DDT increased significantly (P less than 0.01) in infant whole blood with infant age. Multiple regression showed that 70.0% of the variation in sigma DDT was due to the variation in parity of the mother, age of the infant, and the sigma DDT in breast milk. These variables accounted also for 76.3% of the variation in p,p'-DDE but only for 38.2% of that in p,p'-DDT. Organochlorines were therefore largely transferred to the infant from the mother, with DDT in the environment playing a secondary role.

Age Factors↗
PubMed1991

The prevalence of homocysteinemia and hypercholesterolemia in angiographically defined coronary heart disease.

Total serum homocysteine and cholesterol levels were determined in 163 male patients with typical angina who were subjected to coronary angiography. The prevalence of homocysteinemia in coronary heart disease (CHD) was 41.9%. Serum homocysteine levels were significantly elevated (p less than 0.05) in patients with major occlusion in two or three coronary arteries. Furthermore, the prevalence of homocysteinemia correlated positively (p less than 0.05) with the number of coronary vessels that were occluded. The prevalence of hypercholesterolemia was 34.9%, but, in contrast to homocysteinemia, no graded strength of association with the number of stenotic coronary arteries could be demonstrated. The results suggest that homocysteinemia may contribute significantly to the development of coronary heart disease.

Adult↗
PubMed1991

Epidemiological reference ranges for low-density lipoprotein cholesterol and apolipoprotein B for identification of increased risk of ischaemic heart disease.

Although there is widespread acceptance that total cholesterol (TC) value reference ranges should be based on epidemiological rather than statistical considerations, the epidemiological action limits for low-density lipoprotein cholesterol (LDL-C) are still incomplete and only statistical reference ranges for apolipoprotein B (Apo-B) levels are available. The combined use of epidemiological reference ranges for TC and incomplete or statistical reference ranges for LDL-C and Apo-B is illogical, since these parameters may fall into discordant risk categories that will hamper and complicate the management of hypercholesterolaemia. Based on a study of lipograms obtained from +/- 3,000 inhabitants of two industrialised Transvaal towns, the age-related epidemiological reference ranges for LDL-C and Apo-B were established. A comparison with published observational studies of other populations, in which comparable lipid, lipoprotein and apolipoprotein methodologies were used, reflected the severity of these lipid-related abnormalities in white South Africans, especially after the age of 30 years. In addition, the serum TC values found in this survey were not significantly different from those obtained 10 years ago.

Adolescent↗
PubMed1991

Serum levels of DDT and liver function of malaria control personnel.

The levels of DDT and metabolites in serum of 23 applicators involved in malaria control operations in Natal were determined using gas chromatography with electron capture detection. The mean levels (microgram/l, ppb) were 61.7 DDT, 129.3 DDE, 11.0 DDD and 202.0 sigma DDT. Percentage DDT was 33.4%. These levels were higher than for an age matched sample of the general population in KwaZulu, who are protected by DDT against malaria. Percentage DDT correlated negatively with age (P less than 0.05) for the applicators, suggesting a change in pharmacodynamics with age. Mean serum albumin, alkaline phosphatase, aspartate transferase and gamma-glutamyltransferase (GGT) levels did not differ significantly from an age-matched control group, but the mean GGT value for the applicators was higher than the maximum of the laboratory normal range. Although not clinically significant, the alanine transferase was significantly higher in the applicators than in the control group. These higher levels suggest a possible risk to the health of the sprayers, but uncertainties remain.

Adult↗
PubMed1991

Evaluation of the results of oesophagectomy for oesophageal cancer.

The long-term results of standard techniques of oesophagectomy were examined in 127 patients with squamous cell carcinoma of the oesophagus. A near-total oesophagectomy with a cervical anastomosis was performed in 93 patients and an oesophagogastrectomy with an intrathoracic anastomosis was carried out in 34 patients. One hundred and eight patients had a curative oesophagectomy and 19 patients had a palliative resection. Eight patients received radiotherapy to the tumour bed. There were 15 deaths in hospital and the overall 5-year survival rate including perioperative deaths was 13.2 per cent. Survival was adversely affected by incomplete excision of macroscopic tumour (P less than 0.001), positive regional lymph nodes (P less than 0.05) and distant lymphatic metastases (P less than 0.02). The 5-year survival rate of patients with tumour invasion beyond the oesophageal wall (T3) and negative nodes was 20 per cent. Postoperative irradiation had no effect on the survival of patients with gross residual tumour. Complete clearance of microscopic tumour was achieved in 50 per cent of patients with T3 tumours and this group did not benefit from adjuvant radiotherapy. Survival in patients undergoing curative oesophagectomy with residual microscopic tumour, however, was significantly improved by irradiation of the tumour bed (P less than 0.01). These results suggest that the survival of patients can be increased significantly by the excision of all gross tumour and by identification of those who will benefit from local radiotherapy.

Adult↗
PubMed1991

Ethnic immunity to coronary heart disease?

Dietary fat intake is often regarded as a major determinant of coronary heart disease (CHD) rate and it has been deemed unnecessary to invoke racial or other factors to explain the differences in CHD rates among different ethnic groups. Despite a high prevalence of CHD risk factors such as hypertension, obesity, and smoking, CHD remains a rarity in westernized black Africans. Cord blood total cholesterol (TC), low density lipoprotein cholesterol (LDLC) and apolipoprotein B (apo B) levels were measured and found to be respectively 12.1%, 18.3% and 22.4% lower in black neonates when compared to white neonates. These differences were again studied in a group of young black African males and a comparable group of age-matched whites who had been exposed to the same environment and western diet for at least 2 years. Although the body mass indices and serum albumin concentrations in the adult males were not significantly different, serum levels of TC, LDLC and apo B were 10.7%, 18.7% and 39.7% lower in the blacks, respectively. Furthermore, high density lipoprotein cholesterol (HDLC) and Apolipoprotein AI were 20.2% and 9.5% higher, homocysteine 45.6% lower and coagulation factor VII 26.6% lower in the adult black Africans. It is concluded that blacks are biochemically less responsive to an atherogenic diet than whites and these differences are already present at birth.

Adult↗
PubMed1991

Malaria control and levels of DDT in serum of two populations in Kwazulu.

Concentrations of p,p'-DDT, p,p'-DDE, and p,p'-DDD were determined in serum of members of households of two different areas of KwaZulu. Annual intradomiciliary application of DDT is used for the interruption of malaria transmission in one area (the exposed group) while the other served as the control. Demographic differences between the two groups resulted in significantly more females in the control group. The two groups were comparable with respect to age. Serum from household members living in DDT-treated dwellings had significantly higher (p less than .005) levels of sigma DDT and metabolites (mean sigma DDT 140.9 micrograms/l) than those from the control area (mean sigma DDT 6.04 micrograms/l). Percentage DDT was also significantly higher (p less than .05) in the exposed group (28.9%) than the control group (8.3%). sigma DDT for the 3-10 yr age interval (168.6 micrograms/l) was significantly higher (p less than .05) than the 20-29 (60.5 micrograms/l) and 30-39 (84.2 micrograms/l) yr age intervals. There seemed to be two groups with regard to accumulation and elimination. The age group 3-29 appeared to be eliminating DDT, most likely accumulated from contaminated breast milk, faster than they accumulated it. From around 29 yr of age accumulation predominated as the levels increased with age. Regression analysis suggested pharmacokinetic differences for DDE and DDT between the two groups. Liver function parameters between the two groups only differed significantly for gamma-glutamyl transferase (gamma GT) (p less than .005), but the influence of difference in alcohol consumption, which was significantly higher in the exposed group (p less than .0001), offered a better explanation. Those of the exposed group that consumed alcohol had a significantly higher (p less than .05) mean gamma GT level (41.5 IU/l) than those that did not (20.2 IU/l), but were not significantly different for sigma DDT (p greater than .05). The safety of DDT used in malaria control for subjects aged 3 and older was confirmed by the levels of DDT in serum when compared with other studies, which showed lack of any negative effects associated with these levels in adults, and an apparently normal liver function in the exposed and control groups.

Adolescent↗