In vitro permeation of platinum through African and Caucasian skin.

The majority of the South African workforce are Africans, therefore potential racial differences should be considered in risk and exposure assessments in the workplace. Literature suggests African skin to be a superior barrier against permeation and irritants. Previous in vitro studies on metals only included skin from Caucasian donors, whereas this study compared the permeation of platinum through African and Caucasian skin. A donor solution of 0.3 mg/ml of potassium tetrachloroplatinate (K2PtCl4) dissolved in synthetic sweat was applied to the vertical Franz diffusion cells with full thickness abdominal skin. Skin from three female African and three female Caucasian donors were included (n=21). The receptor solution was removed at various intervals during the 24 h experiment, and analysed with high resolution inductively coupled plasma-mass spectrometry (ICP-MS). Skin was digested and analysed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Significantly higher permeation of platinum through intact African skin (p=0.044), as well as a significantly higher mass of platinum retention in African skin in comparison with Caucasian skin (p=0.002) occurred. Significant inter-donor variation was found in both racial groups (p<0.02). Results indicate that African workers have increased risk of dermal permeation and therefore possible sensitisation caused by dermal exposure to platinum salts. These results are contradictory to limited literature suggesting a superior barrier in African skin and further investigation is necessary to explain the higher permeation through African skin.

In vitro permeation of platinum and rhodium through Caucasian skin.

During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace.

Dermal exposure and changes in skin barrier function of base metal refinery workers co-exposed to cobalt and nickel

Refinery workers are exposed to many metals; including cobalt and nickel; both of which are skin sensitisers; causing allergic contact dermatitis. Dermal exposure; and changes in skin barrier function [skin hydration; transepidermal water loss (TEWL) and skin surface pH] from start to end of shift; of base metal refi nery workers co-exposed to cobalt and nickel; were assessed. Changes in SH were inconsistent; while TEWL generally increased and SS-pH decreased. The decrease in SS-pH is most likely due to direct skin contact with sulphuric acid. Dermal exposure was variable even though workers wore personal protective gloves; highlighting the limitations of personal protective clothing in controlling exposure. None of the workers presented with allergic contact dermatitis (ACD). The small sample size of this study limits the interpretation of the absence of ACD; but the healthy worker effect and ethnic differences in skin structure and function may be contributing factors

DNA damage and repair detected by the comet assay in lymphocytes of african petrol attendants: a pilot study.

Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxic and carcinogenic effects. The single-cell gel electrophoresis assay (comet assay) is a method highly sensitive to DNA damage induced by environmental and occupational exposure to carcinogenic and mutagenic agents. The aim of this study was to evaluate the level of exposure of petrol attendants to petrol VOCs and also to determine their effect on DNA damage and repair in lymphocytes of African petrol attendants. The exposed group consisted of 20 subjects, randomly selected from three petrol stations. A control group of 20 unexposed subjects was also chosen and matched for age and smoking habits with the exposed group. Sorbent tubes were used to assess personal exposure of petrol attendants. The comet assay was used to investigate the basal DNA damage and repair capacity in isolated lymphocytes of petrol attendants and unexposed subjects. Blood samples were taken from the petrol attendants at the end of their 8-h working shift and also from the unexposed subjects. The petrol attendants were found to be exposed to levels of petrol VOCs lower than the South African occupational exposure limit for constituent chemicals. A significant relationship was found between the volume of petrol sold during the shift and the average concentrations of benzene, toluene and the total VOCs measured. However, relative humidity had a negative correlation with the average concentrations of benzene, toluene, xylene and the total VOCs. Significantly higher basal DNA damage was observed with the exposed group compared to the unexposed group. The period of exposure influenced the level of DNA damage and the calculated repair capacity. Smoking and age had a significant influence on the level of DNA damage. DNA repair capacity was delayed in smokers of both exposed and unexposed group.

Dermal exposure sampling methods: an overview

Although a total of 174 and 117 substances have been listed with a skin (Sk) notation in the Regulations for Hazardous Chemical Substances and Regulation 22.9 of the Mine Health and Safety Act respectively; dermal sampling is not used frequently to assess exposure to these substances. A variety of measurement methods and strategies have been developed during the past forty years to assess dermal exposure. These methods include interception methods (also referred to as surrogate skin methods); removal of contaminant (substance) methods and in situ detection methods (also referred to as fluorescent tracer methods). The aim of this paper is to give an overview of the different dermal sampling methods. Furthermore; the applicability of each method for sampling different hazardous chemical substances will be highlighted in order to assist Occupational Hygienists in choosing the correct dermal sampling method

Cardiovascular reactivity in Black South-African males of different age groups: the influence of urbanization.

OBJECTIVE: Blacks in an urban environment seem to be more vulnerable to excessive increases in blood pressure during daily life events. This greater cardiovascular reactivity during acute stress situations in urban Blacks may lead to the development of hypertension in their later lives. Because Blacks in South Africa are involved in a massive process of urbanization, which may lead to chronic diseases of lifestyle like hypertension and diabetes, this study was undertaken to compare the cardiovascular reactivity patterns of urbanized and rural Black males in the North-West province of South Africa. DESIGN: Two hundred twenty-three Black males of different age groups, Group 1: younger than 25 years of age; Group 2: between 25 and 44 years of age; and Group 3: 45 years of age and older. Participants were randomly selected from rural and urbanized settlements. METHODS: After resting blood pressure was recorded with a Finapres apparatus, and cardiac output, stroke volume, heart rate, and total peripheral vascular resistance had been obtained, an acute laboratory stressor (hand dynamometer exercise) was applied and the above measurements repeated. RESULTS: The SBP, DBP, and MAP increased 28% and 42% in both the rural and the urbanized groups. There was a shift from a central reactivity pattern (increased cardiac output) in the young rural group (< 25 years) to a peripheral reactivity pattern (increased total peripheral resistance) in the > or = 45 years old urbanized males after applying the stressor. CONCLUSIONS: Cardiovascular reactivity differs between Black males from a rural area compared to urbanized Black males. The urbanized males > or = 45 years of age were at a higher risk of developing cardiovascular disease because their total peripheral resistance reactivity increased the most during application of the stressor.

Prolactin, testosterone and cortisol as possible markers of changes in cardiovascular function associated with urbanization.

People living in large informal settlements in South Africa showed a significant increase in cardio/cerebrovascular disease. This study was undertaken to compare the cardiovascular and endocrine parameters of urbanized and rural black female and males. The hormone levels such as prolactin, cortisol and testosterone may also change with urbanization and could make a contribution to the high rate of hypertension. For this study, 1202 black subjects were selected from 37 randomly selected rural and urbanized settlements. Resting blood pressure was recorded with a Finapres apparatus. Cardiac output, stroke volume, heart rate, total peripheral vascular resistance and compliance had been obtained with the Fast Modelflow software program. An acute laboratory stressor (hand dynamometer exercise) was applied to challenge the cardiovascular system and the measurements were repeated. Blood sampling was done and hormone levels were determined by biochemical analyses. For females, significant lower levels of cortisol were found in the urban strata in comparison with the rural strata. The testosterone levels were significantly lower and the prolactin levels significantly higher for females in the informal settlements compared with the rural strata. It is noticeable that most cardiovascular parameters showed the highest changes with the application of the stressor in the informal settlement strata and the lowest in people living on farms for both male and female. The prolactin levels in males are significantly higher in the informal settlement stratum. Subjects living in informal settlements showed a noticeable endocrine pattern of ongoing stress that can be associated with changes in the cardiovascular parameters with urbanization. This can partly explain the reported high rate of cardio/cerbrovascular disease in black South Africans living in informal settlements.

Safety and efficacy of pantoprazole 40 mg daily as relapse prophylaxis in patients with healed reflux oesophagitis-a 2-year follow-up.

BACKGROUND: Pantoprazole is a benzimidazole derivative which selectively inhibits the proton pump H+, K+-ATPase, necessary for the final step in gastric acid secretion. AIM: To assess safety and efficacy of oral pantoprazole (40 mg o.d.) used as a prophylaxis against relapse in patients with healed reflux oesophagitis during an open-label, 2-year study. METHODS: Outpatients (n=157) with healed stage II or III reflux oesophagitis (Savary-Miller classification) were enrolled into a long-term, multicentre maintenance study. Endoscopy was performed at entry into the study, after 12 and 24 months, or when disease-specific symptoms occurred on more than three consecutive days. Symptoms were assessed at 3-monthly intervals. Endoscopically confirmed relapses (at least stage I) were evaluated as treatment failures. RESULTS: Of the 178 adverse events, experienced by 88 (56%) patients (intention-to-treat population), 12 (7%) were assessed by the investigators as possibly related to the study medication. Median serum gastrin levels increased from a baseline of 46 ng/L to 90 ng/L, reaching a plateau after 9 months. For the intention-to-treat population the endoscopic remission rates after 12 and 24 months were 87% and 76%, respectively (Life-Table survival analysis, Kaplan-Meier). CONCLUSION: Pantoprazole 40 mg proved to be safe and efficacious during a 2-year prophylaxis treatment in patients with healed reflux oesophagitis.

Haemodynamic changes in the cardiovascular system during the early phases of orthostasis.

In this study, we monitored the changes in arterial blood pressure continuously in two groups of Caucasian men during normal passive orthostasis as well as reversed passive orthostasis. Group A consisted of a group of 23 younger men (16 +/- 0.5 years) and group B consisted of 21 older men (62.9 +/- 2.7 years). The normal passive orthostatic test and the reversed passive orthostatic test were used to induce blood pressure changes. We found that the temporary and initial changes in blood pressure during the normal and reversed orthostatic tests were significantly lower in the older group. Heart rate increases were also lower in the older group. These findings could be explained in terms of a reduced compliance of the thin walled venous blood vessels in the elderly.

Efficacy and tolerability of pantoprazole 40 mg versus 80 mg in patients with reflux oesophagitis.

BACKGROUND: Pantoprazole is a substituted benzimidazole which is a potent inhibitor of gastric acid secretion by its action upon H+, K+-ATPase. METHODS: Pantoprazole 40 mg and 80 mg were compared in a randomized double-blind study in 192 out-patients with stage II or III (Savary-Miller classification) reflux oesophagitis. Patients received either pantoprazole 40 mg (n = 97) or pantoprazole 80 mg (n = 95), once daily before breakfast for 4 weeks. Treatment was extended for a further 4 weeks if the oesophagitis had not healed. RESULTS: After 4 weeks complete healing of the reflux oesophagitis was seen in 78% of protocol-correct patients given pantoprazole 40 mg daily (n = 86), and in 72% in the 80 mg (n = 87) group. The cumulative healing rates after 8 weeks were 95 and 94%, respectively (P > 0.05, Cochran-Mantel-Haenszel), and time until healing of oesophagitis comparable in both groups. Differences between doses were also not significant in an intention-to-treat analysis. Both dosing schedules were well tolerated and the patients experienced remarkable symptom relief. No adverse event or changes in laboratory values of clinical significance could definitely be ascribed to the trial medication. CONCLUSION: The 40 mg pantoprazole dosage is comparable to 80 mg in reflux oesophagitis, both in efficacy and tolerability.

Fluorescence microscopy of the avian (Gallus domesticus) carotid body.

Sterba's technique to detect neurosecretory substances was applied to carotid body tissue, surrounding branchial derivatives, ganglion nodosum and the carotid arterial wall. Mainly a yellowish-green, a yellowish-red and a bright yellow fluorescence was observed as well as greenish-yellow fibres with varicosities and terminal knobs. The metachromatic reaction of the technique was briefly discussed.

The ultrastructure of epithelioid cells in the avian (Gallus domesticus) carotid body.

10 clinically healthy white leghorn males were utilised for this investigation. Apart from toluidine blue-pyronin-stained Araldite sections, uranyl acetate and lead monoxide staining revealed three types of epithelioid cells. Nuclear and cytoplasmic contents, especially three types of granules, conveniently designated as q, r and p granules, are described in detail and tabulated. Technical difficulties in obtaining carotid body tissue as well as clear-stained sections for ultastructural studies are mentioned.

Histocytology of the avian (Gallus domesticus) carotid body.

The histotopography of the silvery-white glistening carotid body and the branchial derivates in the cranial thoracic inlets as well as the histocytology of the particular organ were revealed by various microtechniques. Three types of randomly distributed epithelioid cells, many capillaries, and small and large sinuses are observable. Myelinated fibres are sparsely distributed. 25 clinically healthy white leghorn males were used for this investigation.

Excision and localisation of the avian (Gallus domesticus) carotid body.

The anatotopography of cranial thoracic inlets, the carotid body and associated structures in the caudal pole of the thyroid gland are described. The source from which the various groups of fowls (n = 65) were obtained as well as the varied localisation of the carotid body are indicated. In this investigation, the carotid body was found to be situated mostly (49 cases) either on or in the immediate vicinity of blood vessels (carotid and inferior thyroid artery) and only in 14 cases in close association with the parathyroids.