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Biomedical subjects

C A Van der Merwe

Publications and source records attributed to C A Van der Merwe.

14 recordsLinked to original sources
PubMed1996

Increased levels of autoantibodies to cardiolipin and oxidised low density lipoprotein are inversely associated with plasma vitamin C status in cigarette smokers.

In this study we have measured circulating levels of autoantibodies to cardiolipin and oxidised low-density lipoprotein (ox-LDL) and correlated these with plasma concentrations of the anti-oxidant nutrients vitamin C, vitamin E and beta-carotene, in a group (79) of asymptomatic, male cigarette smokers and in non-smoking control subjects. Cigarette smoking, a well-known risk factor for development of atherosclerosis, was found to be associated with moderately elevated levels of autoantibodies to both cardiolipin and ox-LDL. Increased levels of these autoantibodies were most evident in the older smokers (> 30 years) and were significantly and inversely correlated with plasma vitamin C, but not with vitamin E or beta-carotene. Absorption studies designed to investigate the specificity of these autoantibodies demonstrated a high degree of cross-reactivity of cardiolipin antibodies with ox-LDL, while antibodies to the oxidatively modified lipoprotein tended to be specific for this antigen. These findings suggest that cigarette smoking promotes formation of autoantibodies to both cardiolipin and ox-LDL and that these may be involved in the initiation and/or perpetuation of atherosclerosis. Dietary intake of vitamin C may be a determinant of susceptibility to development of this cardiovascular disorder.

Adult↗
PubMed1995

Plasma levels of beta-carotene are inversely correlated with circulating neutrophil counts in young male cigarette smokers.

Relationships between plasma levels of beta-carotene (BC) and the numbers and oxidant-generating activities of circulating neutrophils have been investigated in a group of asymptomatic young male cigarette smokers (N = 40) and in a group of nonsmoking control subjects. Plasma BC levels were measured using HPLC, while oxidant generation was measured using a phorbol myristate acetate (PMA) activated whole blood luminol-enhanced chemiluminescence (LECL) method. Relative to nonsmokers, the numbers of circulating neutrophils, as well as the LECL responses of these cells, were increased by 41% (p = 0.0001) and 47% (p = 0.004), respectively, while plasma BC levels were decreased by 24% (p = 0.01). In cigarette smokers, but not in nonsmokers, the numbers of circulating neutrophils, as well as the LECL responses of these cells, were significantly and inversely correlated with plasma BC levels (r = -0.36, p = 0.02; and r = -0.33, P = 0.04 respectively). Diminished plasma levels of BC in cigarette smokers probably reflect the increased numbers and prooxidative activities of circulating neutrophils. Intake of this antioxidant nutrient may be a determinant of susceptibility to smoking-related pulmonary dysfunction mediated by oxidants derived from smoke-activated phagocytes.

Adult↗
PubMed1994

Biochemical analysis of tunica vaginalis fluid in patients with or without idiopathic hydroceles.

OBJECTIVE: To establish the differences, if any, between the biochemical composition of idiopathic hydrocele fluid and the fluid normally present in the tunica vaginalis. PATIENTS AND METHODS: Aspiration and sclerotherapy of 37 idiopathic hydroceles from patients who presented to this urology clinic were performed. The biochemical content of the fluid was compared with that of the tunica vaginalis fluid from a small group of controls (n = 8), taken from patients undergoing orchidectomy for carcinoma of the prostate. RESULTS: Differences in several measurements were recorded; in particular, there were significantly higher concentrations of calcium, albumin, total protein and creatine-kinase in the hydrocele group. The levels of potassium, aspartate transaminase, alanine transaminase and alkaline phosphatase were significantly lower in the hydrocele group. CONCLUSION: Whether these differences have a role in the causation of an idiopathic hydrocele is, at this stage, speculative. A similar study on a larger scale would probably be more conclusive.

Albumins↗
PubMed1992

Treatment of Raynaud's phenomenon with triiodothyronine corrects co-existent autonomic dysfunction: preliminary findings.

Cardiovascular autonomic function was assessed in 9 subjects with Raynaud's phenomenon. The underlying diseases were systemic lupus erythematosus (n = 5), systemic sclerosis (n = 3) and rheumatoid arthritis (n = 1). Five standard non-invasive tests, 3 of heart rate and 2 of blood pressure, were employed. Compared with age and sex matched controls (n = 25), the number of values abnormal was 24 of 45 (53%) overall and between one and 4 (median, 2) individually. Significant differences were present for 3 tests, two of heart rate and one of blood pressure. The subjects were given triiodothyronine, 60 to 80 micrograms per day, for vasospastic attacks. Autonomic function was reassessed between weeks 4 and 9 (9 subjects) and between weeks 12 and 18 (8 subjects) after introduction of triiodothyronine. Test results showed a considerable improvement. At the second reassessment, the number of values abnormal was now 5 of 40 (12.5%) overall and nil (n = 4) or one (n = 4) individually. Significant differences remained for one heart rate test only. Adverse side effects to triiodothyronine occurred in a single subject and were readily controlled. Evidence of somatic neuropathy was present electrophysiologically in all 9 subjects and clinically in 8. Triiodothyronine may have corrected autonomic dysfunction by increasing blood flow to ischaemic peripheral nerves or by acting on the autonomic system more directly. Further study of triiodothyronine in autonomic insufficiency appears merited.

Adult↗
PubMed1990

Investigation of the effects of oral administration of vitamin E and beta-carotene on the chemiluminescence responses and the frequency of sister chromatid exchanges in circulating leukocytes from cigarette smokers.

Sixty asymptomatic cigarette smokers were randomly allocated into three treatment groups. Smokers in Group 1 received 900 international units of Vitamin E (VE) daily for 6 wk, whereas 40 mg of beta-carotene (BC) daily was administered to those in Group 2 for the same period. Subjects in Group 3 were treated with a matched placebo. Plasma levels of VE and BC as well as circulating leukocyte counts, sister chromatid exchanges (SCEs), and the luminol-enhanced chemiluminescence (LECL) responses of blood phagocytes activated with phorbol myristate acetate (PMA) and FMLP with cytochalasin B (FMLP/CB) were measured prior to the administration of the antioxidant/placebo after 4 and 6 wk of supplementation and 12 wk after cessation of treatment. SCEs and leukocyte counts remained unchanged throughout the trial in all three treatment groups. Administration of VE for 4 wk was accompanied by decreased FMLP/CB-activated (p less than 0.005) and PMA-activated (p less than 0.005) LECL responses. However, with PMA as stimulant, the inhibition of LECL was transient, with partial recovery observed after 6 wk despite continued administration of VE. Administration of BC was associated with progressive inhibition of both FMLP/CB-activated (p less than 0.05 and p less than 0.01 after 4 and 6 wk, respectively) and PMA-activated (p less than 0.025 after 6 wk) LECL. No alterations in LECL responses were observed in Group 3 (placebo). VE appeared to inhibit the generation of oxidants by activated phagocytes, whereas BC scavenged oxidants generated by the myeloperoxidase/H2O2/halide system.

Acridines↗
PubMed1990

Investigation of the role of phagocytes and anti-oxidant nutrients in oxidant stress mediated by cigarette smoke.

In this study we have correlated the plasma levels of the anti-oxidant vitamins C and E, and beta-carotene with smoking histories, the release of reactive oxidants from circulating phagocytes and spirometry in asymptomatic cigarette smokers. Smoking histories, the generation of reactive oxidants by activated phagocytes and spirometric abnormalities were strongly inter-correlated. However, plasma levels of the anti-oxidant nutrients did not correlate with any of the other measured parameters. These findings indicate that plasma levels of vitamins C and E, and beta-carotene are apparently not predictive of predisposition to oxidant-mediated-spirometric abnormalities in cigarette smokers.

Antioxidants↗
PubMed1989

Exogenous ochronosis: an epidemiological study.

A survey was conducted to investigate the relationship between exogenous ochronosis and the use of skin lightening preparations amongst black individuals attending general outpatient departments in two South African hospitals. In the sample, 15% of males and 42% of females were found to have exogenous ochronosis. The prevalence amongst users of skin lighteners was 69%. The main demographic associations with ochronosis were an inverse relationship to education, and predominance of the female sex. Clinical and behavioural aspects were also recorded. Even products limited to 2% hydroquinone or less, and combined with a sunscreen, were found to cause ochronosis.

Adolescent↗
PubMed1989

Spirometric abnormalities in young smokers correlate with increased chemiluminescence responses of activated blood phagocytes.

Spirometric values determined from the flow-volume loops of 60 healthy young smokers (mean age, 28 +/- 0.6 yr) were correlated with measurements of the release of extracellular and intracellular reactive oxidants (RO) as determined by luminol-enhanced chemiluminescence (LECL) from peripheral blood activated with the synthetic chemotactic tripeptide FMLP combined with cytochalasin B (CB). Fractionation and reconstitution experiments revealed that LECL originated predominantly from polymorphonuclear leukocytes (PMNL). Circulating total leukocyte counts and serum thiocyanate levels were also determined. The data were analyzed using Spearman's correlation coefficient and by multiple regression analysis. Cigarette smoking was associated with elevated intracellular and especially extracellular LECL responses, the latter being strongly correlated (p less than 0.0001) with cigarettes smoked per day, serum thiocyanate levels, circulating leukocytes, and PMNL counts. Abnormalities of the spirometric parameters FEV1/FVC, FEF50/FVC, FEF25, FEF25-75, and FEF75-85 correlated best with extracellular LECL (p less than 0.0002 to p less than 0.0001), but also with pack-years (p less than 0.006 to p less than 0.0001), cigarettes smoked per day (p less than 0.008 to p less than 0.0002), thiocyanate levels (p less than 0.04 to p less than 0.002) and leukocyte counts (p less than 0.03 to p less than 0.002). According to stepwise multiple regression analysis of the data the combination of the independent variables extracellular LECL, pack-years, and numbers of circulating PMNL accounts for 35.6% of the variation in lung function in the group of cigarette smokers, with LECL being the most important contributor (26%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Race-gender differences in serum creatine kinase activity: a study among South Africans.

Higher levels of total serum creatine kinase activity have been reported in black compared with white North Americans of the same sex. In a study among South Africans, we found such an interracial difference was notable only for males. The difference was heightened by physical activity. This study affirms the importance of sampling the indigenous population when developing a reference range for total creatine kinase activity.

Adult↗
PubMed1988

Malignant pleural mesothelioma: a disease unaffected by current therapeutic maneuvers.

From 1965 to 1985, 262 patients with malignant pleural mesothelioma were treated with cytostatics only; radiotherapy (RT); RT and cytostatics; or decortication plus RT plus cytostatics. The median survival (MS) from diagnosis was 9.6 months. This was similar for all comparable treatment groups. In a univariate analysis, significant favorable prognostic factors were good performance status (PS), duration of symptoms greater than 6 months at the time of diagnosis, early stage of disease, white race, and female sex. In a multivariate analysis, PS, race, duration of symptoms, and stage were of significance for a favorable prognosis. Age, pain as first symptom, histologic subtype, and RT dose were not of prognosis significance in this study. The stepwise addition of treatment modalities did not increase survival, which remained the same as that reported for untreated patients. Therefore, phase II trials of new agents offer the only hope for advance in the treatment of this disease.

Adult↗
PubMed1987

An improved statistical method for the racial classification of man by means of palatal rugae.

A classification of human ruga pattern disclosed interracial differences between six population groups. The conventional statistical procedures of linear and quadratic discriminant function and nearest neighbour-point-method delivered overall correct classification figures of 49.2, 45.3 and 29.1 per cent respectively. The jackknife-classification matrix for the kernel-function method delivered an overall percentage correctly classified of 61.1 per cent with an individual group figure range correctly classified of 37-100 per cent. Although computationally elaborate, this technique has led to new insights into the data compared with parametric methods.

Humans↗
PubMed1985

The antiestrogenic effect of clomiphene on perineal tumescence of the baboon in an in vitro fertilization program.

In a nonhuman primate in vitro fertilization program clomiphene citrate was used to superovulate the chacma baboon Papio ursinus. The antiestrogenic effect of clomiphene citrate was demonstrated locally on the perineal tumescence. In comparing the result of 50 spontaneous cycles and 18 clomiphene citrate-stimulated cycles, there was a statistical significant influence on cycle length and duration and degree of perineal swelling. This inhibitory effect on perineal tumescence of the baboon is another example of a local antiestrogenic effect of this drug. Furthermore, it nullified an important clinical parameter of ensuing ovulation.

Animals↗