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T J Kotze

Publications and source records attributed to T J Kotze.

At least 19 recordsLinked to original sources
PubMed2003

In vitro human dental enamel erosion by three different wine samples.

The aim of this study was to investigate the erosive effect of different wine samples on the enamel of human permanent teeth. Twenty-one extracted, sound, permanent human incisor teeth were imbedded in epoxy resin and seven immersed in each of the three different wine samples for 0, 2, 5, 15, 30, 45 and 60 minute periods. The Knoop hardness for each tooth at each of the immersed periods was determined as a measure of the degree of enamel erosion (demineralisation). The main finding was that all three wines eroded enamel (softer enamel) which should mainly be due to their very low pH values (3.2, 3.7, 3.8) and high total acid content. From the Wilcoxon non-parametric tests it was clear that wine 2 had the severest influence on the hardness of the teeth, and the wines differed significantly (p < 1%) from 30 minutes onwards. These tests showed that wine 1 differed significantly from wine 2 from 30 minutes onwards and so did wine 3, but wines 1 and 3 did not differ at all (p > 5%). It is concluded that all three wine samples were erosive to enamel and it is difficult to predict the relative erosion rate of different kinds of wines according to their chemical compositions, as this process is most probably governed and affected by a large number of a combination of factors. The only reliable way to know the exact degree of erosion of a specific wine is by means of a laboratory study. Possible ways to decrease the damaging effect of erosion caused by wine are provided.

Analysis of Variance↗
PubMed2000

The relation between lead concentrations in human dental tissues and in blood.

The purpose of this study was: (1) to measure the lead concentrations in various parts of the teeth (enamel, dentine and circumpulpal dentine) and in blood from individuals of a remote rural South African community; (2) to investigate any correlation between the lead concentrations in these various dental tissues and in blood; and (3) to estimate blood lead from the tooth lead concentrations reported in other studies. Primary teeth and blood were collected from 48 children and analysed by graphite-furnace atomic absorptiometry. The following median concentrations (expressed in mg/kg) of lead were found: blood, 0.025; enamel, 0.25; dentine, 2.04; circumpulpal dentine, 6.71. The tooth lead concentrations were similar to those from other studies from remote rural areas but comparisons of blood lead were not possible in the absence of previous data. Blood lead in other studies could be calculated from the ratios here reported.

Child↗
PubMed2000

Protein-energy malnutrition as a risk factor for increased morbidity in long-term hemodialysis patients.

This prospective nonintervention single-center study was undertaken to investigate the role of protein-energy malnutrition (PEM) as a risk factor for morbidity in patients on long-term hemodialysis. Thirty-seven patients from the renal unit of Tygerberg Hospital, Tygerberg, South Africa, were studied for a mean period of 26 months. Morbidity was the main outcome and was defined as the number of hospitalizations and days of hospitalization per patient per year. Investigations included 4-monthly determinations of interdialytic protein catabolic rate (PCR), dietary intake of protein and energy, blood levels of albumin and urea, lymphocyte count, adequacy of dialysis (Kt/V), body weight, intradialytic weight loss, fat mass (FM), fat-free mass (FFM), body mass index (BMI), and bone-free arm muscle area (BF-AMA). A PEM composite score was derived from postdialysis serum albumin, BF-AMA, FM, FFM, and BMI. All-cause morbidity as defined by number of hospitalizations (see text for other definitions of morbidity) showed a significant correlation with the mean and baseline PEM score (P <.01), and a negative correlation with predialysis and postdialysis serum albumin (P <.05) and age (P <.05). There was no significant relationship with PCR, percentage intradialytic weight loss, Kt/V, reuse of dialyzer, period on maintenance hemodialysis, sex, race, and type of dialyzer membrane. When "only infection-related" morbidity was considered, the factors that showed a significant correlation were the mean (P <. 001) and baseline PEM score (P <.01), and percentage intradialytic weight loss (P <.01). There was no significant deterioration in the nutritional status of patients followed up for at least 24 months. It is concluded that infection-related morbidity was associated most strongly with the PEM score and the percentage intradialytic weight loss. The results suggest that PEM is one of the important contributing factors to morbidity, possibly via an effect on the immune system and infection.

Adult↗
PubMed1998

An estimation of the genetically significant dose from diagnostic radiology for the South African population, 1990-1991.

The genetically significant dose was initially defined by UNSCEAR in 1958. The National Radiological Protection Board (NRPB) derived a formula from this definition as shown in the NRPB Report, NRPB-R106. It combines the frequency of radiological examinations obtained during the country-wide survey and estimates of gonadal doses for different examination types, together with population and child expectancy data. The task was set to find a model in order to draw the best representative sample of the population, and it was determined in a unique way, namely the so-called Dollar Unit Sampling method. A sample of 27 institutions out of a possible 292 (9%) was drawn. The GSD for the total South African population was calculated, using the above-mentioned formula, as 95 microGy. The breakdown of the genetically significant dose for the various South African race groups was Asian--229 microGy; black--67 microGy; people of color (mixed race)--112 microGy; and white--463 microGy.

Age Factors↗
PubMed1996

An investigation into the prescribing patterns of selective serotonin re-uptake inhibitors in South Africa.

The primary aim of the study was to investigate the prescribing patterns of selective serotonin re-uptake inhibitors (SSRIs) used on a chronic basis in a defined South African patient population, and to calculate the average prescribed daily doses (PDDs) of selected SSRIs. Prescription data for 2117 patients from various medical schemes who were using antidepressant drugs on a chronic basis were analysed retrospectively. More than 70% of all the patients using antidepressants were females. The tricyclic antidepressants (TCAs) and the SSRIs accounted for approximately 75% of all the antidepressants prescribed. The average age of the patients using SSRIs was 48.1 years (SD = 13.4 years). Fluoxetine was the most frequently prescribed SSRI, accounting for 63.3% of all SSRI prescriptions and 21.9% of all antidepressant prescriptions. The average PDDs of citalopram (23.9 mg), fluoxetine (21.7 mg) and paroxetine (21.1 mg) were slightly higher than their defined daily doses (20 mg for all three drugs). The average PDD of fluvoxamine (93.5 mg) was lower than the DDD (150 mg), but was still within an acceptable dose range. It was concluded that fluoxetine was clearly the drug of choice in treating chronic depression in this patient sample, and that the PDDs used in the patient population studied were in agreement with local and internationally acceptable dosage ranges.

Adolescent↗
PubMed1996

The defined daily dose as a measure of drug consumption in South Africa. A preliminary study.

OBJECTIVE: To perform a preliminary investigation into the us e of the defined daily dose (DDD) as a unit to measure drug utilisation in South Africa. The DDD methodology has been applied in many countries in Western Europe and in other parts of the world. However, research using the DDD method is still lacking in South Africa despite the important role that it can play in economic planning and the improvement of prescribing practices. DESIGN: A retrospective drug utilisation study using da ta from a medical aid. Consumption of selected central nervous system drugs in a formulary system was determined. SETTING: Doctors and patients located in an area of Port Elizabeth. PARTICIPANTS: The prescribing behavior of 50 dispensing doctors serving a homogeneous demographic and socioeconomic patient population was analysed. OUTCOME MEASUREMENTS: The DDD/1,000 registered patients/day, the cost per DDD and the relationship between the two units. RESULTS: Values for the DDD/1,000 registered patients/day were on average lower than international values, but similar trends were observed. The cost per DDD for antipsychotic and antidepressant drugs was on average higher than for hypnotic and anxiolytic drugs. There was an inverse relationship between the DDD/1,000 registered patients/day and the cost per DDD. CONCLUSIONS: The DDD methodology is a useful technique to enable drug consumption data to be measured and compared both nationally and internationally. It can be regarded as a valuable tool for the promotion of rational and cost-effective use of medicine in a future health care system for South Africa.

Central Nervous System Depressants↗
PubMed1996

An investigation into the prescribing of analgesics.

OBJECTIVE: To investigate the prescribing of analgesic agents in a defined South African patient population. DESIGN: Retrospective drug utilisation study. SETTING: Prescribing behaviour of a sample of 50 dispensing doctors in Port Elizabeth. Data were obtained from a medical aid which used a formulary system. MAIN OUTCOME MEASURES: Percentage of central nervous system drugs that analgesics comprised; proportion of patients using combination analgesics; cost of analgesics. RESULTS: On average, 83.3% of all central nervous system drugs dispensed were analgesic agents. These agents represented 70.9% of the total cost of central nervous system drugs. A high percentage (82.2%) of the analgesic agents dispensed were combination or polycomponent analgesics. The combination analgesic tablet, consisting of paracetamol, meprobamate, caffeine and codeine phosphate, was the most frequently prescribed central nervous system drug. This product accounted on average for 40.4% of all analgesics dispensed. Nearly half (46.0%) of all the analgesics dispensed by the sample of doctors were available without a prescription. CONCLUSION: The high prescribing rate of combination analgesic prescription was a cause for concern, given the dependence-producing potential of some of the ingredients, e.g. meprobamate. The prescribing and use of analgesics should be carefully monitored by further drug utilisation studies in light of the serious adverse effects, such as analgesic nephropathy, associated with the longterm use of these agents.

Analgesics↗
PubMed1996

A drug utilisation study investigating prescribed daily doses of hypolipidaemic agents.

OBJECTIVES: To estimate average prescribed daily doses (PDDs) for selected hypolipidaemic agents available on the South African market. Comparison of the estimated PDDs with established DDDs (defined daily doses) and international dosage ranges. To investigate the age and gender of the users of the different hypolipidaemic drugs and drug groups. DESIGN: Retrospective drug utilisation study using data from an organisation involved in the pre-certification of chronic medication. SETTING: Doctors and patients in South Africa. Participants. A total of 2,336 patients of various medical aids who were using cholesterol-lowering medication on a chronic basis. OUTCOME MEASURES: The PDDs, for the complete sample and for the age and gender groups. RESULTS: More than 90% of all hyperlipidaemic patients in the study were treated with HMG CoA reductase inhibitors or fibrates. The average PDDs for the three most frequently prescribed lipid-lowering drugs were 414.4 mg for bezafibrate, 12.5 mg for pravastatin and 12.6 mg for simvastatin. The PDDs were on average lower than the established DDDs. Differences were observed in the pattern of lipid-lowering drug prescriptions for women and men. Male users were on average 3.9 years younger than female users. CONCLUSIONS: The PDDs used in the patient population studied were within locally and internationally acceptable dosage ranges, but were generally lower than established DDDs for lipid-lowering drugs. Prescription differences exist between female and male patients and between age groups with regard to chronic medication. Further studies should be conducted to investigate hypolipidaemic drug prescribing in patients who are not on chronic medication.

Adolescent↗
PubMed1995

Vasopressin secretion and memory impairment in alcoholic Korsakoff's syndrome.

The response of arginine vasopressin (AVP) to an intravenous hypertonic saline infusion was investigated in 19 patients with alcoholic Korsakoff's syndrome, 17 non-amnesic alcoholics and 21 non-alcoholic controls. Compared with non-alcoholic controls the Korsakoff patients had elevated basal AVP levels and showed erratic fluctuation of AVP secretion, not related to changes in serum sodium levels. The non-amnesic alcoholics had a similar, but less severe derangement. Neuropsychological tests revealed significant correlations between basal AVP levels and memory performance in the non-amnesic alcoholics, raising the possibility of a common lesion--most likely in the diencephalon--for memory impairment and AVP dysregulation in chronic alcoholics.

Adult↗
PubMed1994

Alkali-soluble and insoluble fluoride in erupted and unerupted human enamel from a high fluoride area with a low fluorosis score.

The amounts of fluoroapatite and 'CaF2-like' fluoride (F) were determined in enamel of unerupted and erupted teeth that had been exposed in vivo to 1.8-2.6 parts/10(6) F in the drinking water and to brushing with F dentifrice at least once a day, and occasionally to a F mouth-rinse (0.022% F). Enamel was sampled by acid-etching and the F levels were measured with an adapted F ion-selective electrode. More F was built into the deeper enamel in the high-F area than in a similar low-F area. Unerupted enamel did not etch significantly (p > 0.05) deeper than erupted enamel. No significant differences (p > 0.05) were found in the F concentrations amongst the following: alkali-washed erupted, unwashed erupted, alkali-washed unerupted and unwashed unerupted at the outer most enamel (approx. 6 microns). However the erupted enamel (alkali-washed or not) showed higher F levels than unerupted enamel (alkali-washed or not) between approx. 6 microns and greater than 100 microns. The increase of F for this high-F area was about 100% in the deeper enamel while for a low-F area it was approx. 78% in the most outer enamel with no increase after a depth of about 20 microns. In contrast to a similar low-F area (water F < 0.10 parts/10(6)), no significant 'CaF2-like' F could be detected in erupted or unerupted enamel for the high-F area.

Dental Enamel↗
PubMed1994

Corticosteroid therapy and bone mass--comparison of rheumatoid arthritis and systemic lupus erythematosus.

This study was designed to evaluate the effects of low-dose corticosteroid (CS) therapy for rheumatoid arthritis (RA) and of high-dose CS therapy for systemic lupus erythematosus (SLE) on metacarpal bone mass in young (premenopausal) subjects. Ninety-eight patients with RA, 63 patients with SLE and 85 healthy controls of comparable age, race, sex and nutritional status were studied. Metacarpal bone mass was measured by radiogrammetry using a digitiser. In the RA patients, mean bone mass of CS-treated subjects (27%) was 52.31 g/cm2, while that of untreated subjects was 56.69 g/cm2 (P < 0.02). In the SLE group, mean bone mass of CS-treated subjects (76%) was 61.47 g/cm2 and that of untreated subjects 62.36 g/cm2 (P > 0.1). Although patients with SLE required larger cumulative doses of CS for longer periods, their bone mass was higher than that of the RA subjects (P < 0.01). None of the patients had femoral neck or vertebral crush fractures. In RA, bone loss was probably a feature of severe disease rather than of CS therapy.

Adrenal Cortex Hormones↗
PubMed1994

Endocrine function in alcoholic Korsakoff's syndrome.

Hypothalamic-pituitary function was studied by means of several dynamic endocrine tests in 19 patients with alcoholic Korsakoff's syndrome, 17 non-amnesic alcoholics and 21 non-alcoholic controls. The responses of thyroid stimulating hormone, prolactin, follicle stimulating hormone, and luteinizing hormone to a combined thyrotropin releasing hormone and gonadoliberin stimulation test did not differ significantly. For the dexamethasone suppression test, the Korsakoff patients had significantly higher basal serum cortisol and 08:00 hr post-dexamethasone cortisol levels than non-alcoholic controls. These findings raise the possibility that chronically elevated cortisol levels may contribute to cognitive impairment in alcoholic Korsakoff's syndrome.

Adult↗
PubMed1993

The influence of consuming fatty fish instead of red meat on plasma levels of vitamins A, C and E.

The effect of fatty fish consumption on the plasma levels of vitamins A, C and E and the intake of these vitamins were studied in 12 males and 16 females with a mean age of 32.4 years. This cross-over study had a 3 week baseline, 6 week experimental and 6 week post-experimental period with a washout period of approximately 3 months in between. Four 7 day dietary records were used to collect dietary information. Blood samples were drawn after an overnight fast at baseline and every third week thereafter. Plasma total cholesterol, high density lipoprotein cholesterol, triacylglycerol, vitamin A, C and E levels were determined. During the experimental periods red meat was consumed by half of the volunteers while fatty fish was consumed by the other half. Diets were crossed-over after the washout period. Plasma levels of vitamins A, C and E remained within normal limits in the experimental periods. The intake of polyunsaturated fatty acids (PUFA) was significantly higher in the experimental fatty fish period than in the experimental red meat period. The dietary ratio of vitamin E: PUFA and the plasma vitamin E level were lower (P < 0.01) in the experimental fatty fish period than in the experimental red meat period but the ratio of plasma vitamin E: total cholesterol plus triacylglycerol did not differ between the experimental periods. In this study none of the experimental groups were at risk in terms of their intake of the antioxidant vitamins.

Adult↗
PubMed1993

Helicobacter pylori prevalence in non-ulcer dyspepsia--ethnic and socio-economic differences.

Helicobacter pylori is an important cause of gastritis and a number of therapeutic trials suggest that it may be important in the genesis of duodenal ulcer recurrence. The reported prevalence of gastric colonisation by the organism varies considerably. The aim of this cross-sectional survey was to determine its prevalence in non-ulcer dyspeptics and to determine whether this is influenced by age, race, sex, socio-economic status, educational level and the number of persons sharing accommodation. One hundred and sixty-nine patients underwent endoscopy; biopsy specimens were taken from the antrum and H. pylori status was determined histologically. Gastric colonisation was found in 106 patients (63%). The prevalence showed a marked ethnic difference: 40% in whites and 71% in coloureds (P < 0.001). The ethnic groups were characterised by significant differences in socio-economic status (P < 10(-6)), educational level (P < 10(-6)), number of persons sharing accommodation (P < 10(-6)) and age (P < 0.001). These same differences were found when comparing the H. pylori-positive and negative groups, but were less marked and could be attributed to the marked differences between ethnic groups. We conclude that H. pylori prevalence differs between the ethnic groups studied. This may be because of varying degrees of exposure risk.

Adult↗
PubMed1992

Endoscopic investigation for gastric cancer in a high-risk group.

Early gastric cancer (EGC) was diagnosed in only a small percentage (less than 1%) of gastric cancer cases seen at Tygerberg Hospital over a 10-year period (1976-1985). This study, aimed at increasing the yield of EGC, was conducted in some high-incidence areas for gastric cancer. Coloured men, who are at high risk for gastric cancer, were identified by their medical practitioners and investigated. A total of 272 coloured males with nonspecific foregut symptoms underwent upper gastro-intestinal endoscopy and multiple biopsy specimens were obtained from all localised mucosal lesions. Twelve gastric cancers were histologically verified, of which 11 were diagnosed in males over 40 years of age. Two EGCs were diagnosed in older males, resulting in a markedly higher proportion of EGC in this subgroup (18.2%) than the proportion of EGC in inpatients at our institution (0.9%). Twenty-two per cent of males over 40 years of age had gastric ulcers compared with 9.2% of younger males. Chronic atrophic gastritis was present in 56.2% of older males but in only 24.6% of younger males. Those over 40 years of age emerged as a subgroup with a high prevalence of gastric cancer and EGC, and concomitant conditions.

Adult↗