The majority of the South African workforce are Africans, therefore potential racial differences ... more 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 hig...
The objectives of this study were to assess dermal exposure of cell workers to nickel at a South ... more The objectives of this study were to assess dermal exposure of cell workers to nickel at a South African base metal refinery and to characterize their skin condition by measuring the skin hydration and trans epidermal water loss (TEWL) indices. The skin hydration index of the index finger, palm, neck, and forehead was measured before, during and at the end of the shift. The TEWL index was measured before and at the end of the shift. Dermal exposure samples were collected with Ghostwipes from the index finger and palm of the dominant hand, before, during, and at the end of the shift. Neck and forehead samples were collected before and at the end of the shift. Wipe samples of various surfaces in the workplace were also collected. Wipes were analyzed for nickel according to NIOSH method 9102, using inductively coupled plasma-atomic emission spectrometry. Hydration indices measured on the hands decreased significantly during the shift, but recovered to normal levels by the end of the shift. TEWL indices for the index finger and palm of the hands are indicative of a low barrier function even before commencement of the shift, which further deteriorated significantly during the shift. During the shift, substantial nickel skin loading occurred on the index finger and palm of the hand. Levels on the neck and forehead were much lower. Various workplace surfaces, which workers come into contact with, were also contaminated with nickel. The skin condition and high levels of nickel on the skin were most probably caused by inadequate chemical protection provided by protective gloves. Although, the permeability of nickel through intact skin is considered to be low, a decreased barrier function of dehydrated or slightly damaged skin will increase its permeability for nickel. The ethnicity of these exposed workers may contribute significantly toward the low incidence of allergic contact dermatitis observed. Several measures to lower dermal exposure to nickel are also recommended.
In this study, we monitored the changes in arterial blood pressure continuously in two groups of ... more 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.
Hairdressers are exposed to numerous hazardous chemical substances, some of which are known or su... more Hairdressers are exposed to numerous hazardous chemical substances, some of which are known or suspected allergens, carcinogens or organic solvents. The objectives of this study were to compare DNA damage and DNA repair capacity between hairdressers with short-term exposure (STE, < 5 years; n = 10), those with longterm exposure (LTE, > 10 years; n = 10), and a control group (n = 11); and to demonstrate that the Comet Assay can be used in biological monitoring to measure the effect of occupational exposure to genotoxic agents in the hairdressing industry. The STE and LTE groups had signifi cantly increased baseline DNA damage compared to the control group. Both the exposed groups also had weaker DNA repair capacity than the control group. The LTE group showed a signifi cantly decreased antioxidant capacity, compared to the control group. Results of this study suggest that the chemicals to which hairdressers are exposed might cause harmful health effects and mutagenic changes.
Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxi... more 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.
ABSTRACT Cardiovascular effects of several physical and psychological stressors were investigated... more ABSTRACT Cardiovascular effects of several physical and psychological stressors were investigated. Indirect continuous blood pressure as well as heart-rate were recorded. Systolic, diastolic, and mean blood pressure as well as heart-rate were recorded. Different patterns of cardiovascular activation during different stressors were obtained. The Valsalva manoeuvre evoked a basic negative feedback baro-receptor response. Physical exercise (bicycle ergometer stress) evoked an overriding of the baro-reflex sympathetic stimulation to fulfil metabolic needs. Psychological stressors such as a TV-game (‘space invaders’), a binary choice program and mental arithmetic produced a pattern of autonomic nervous stimulation which can be described as extra-metabolic or psychophysiological. Possible differences in reaction patterns between psychological stressors are discussed in the light of a literature study. ‘Active’ and ‘passive’ coping may be of importance.
Blacks in an urban environment seem to be more vulnerable to excessive increases in blood pressur... more 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. 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. After resting blood pressure was recorded with a Finapres apparatus, and cardiac output, stroke volume, heart rate, and total peripheral vascular r...
Refinery workers are exposed to many metals, including cobalt and nickel, both of which are skin ... more 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.
The cold pressor test has been widely used in previous cardiovascular reactivity studies as a pre... more The cold pressor test has been widely used in previous cardiovascular reactivity studies as a predictor of hypertension. However, the influence of the physical adaptations of the arterial wall with increasing age on reactivity has not been delineated. 64 men divided into 5 different age groups participated in a laboratory protocol consisting of submerging one hand in ice water for one minute while changes in blood pressure were continuously measured. The results indicated that with increasing age, the systolic blood pressure change, especially the rate of change (slope) is more pronounced than changes in diastolic blood pressure. With increasing age, there is a shift from a diastolic blood pressure reactivity pattern to a more systolic blood pressure reactivity pattern during application of the cold pressor test. This could be ascribed to a decrease in arterial compliance.
Urbanization is a worldwide phenomenon and is most often accompanied by an increased prevalence o... more Urbanization is a worldwide phenomenon and is most often accompanied by an increased prevalence of western-type diseases like hypertension. The higher cardiovascular reactivity (CVR) of black people compared to white people during passive coping stressors has often been linked to their greater vulnerability to hypertension. Blacks, however, display a lower CVR than whites during active coping stressors. In this study it was found that urban blacks show a higher CVR than whites during a passive coping stressor and a lower CVR than whites during an active coping stressor. However, rural blacks consistently show much higher CVR than either whites or urban blacks during both active and passive coping stressors. It seems that CVR is not only a function of the type of stressor applied but can be altered significantly by environmental factors like those experienced during urbanization.
Urbanization is a world-wide phenomenon and results in a radical and sometimes total change in li... more Urbanization is a world-wide phenomenon and results in a radical and sometimes total change in living conditions. This process is accompanied by a significant increase in the incidence of western-type diseases virtually unknown in traditional rural communities. Especially in a multicultural society like South Africa, rural people moving to the city will experience cultural shock leading in many cases to a large degree of acculturation. In this study the effect of acculturation on endocrine reactivity was studied in a population of Tswanas. It was found that significant differences in endocrine reactivity exist not only between rural Tswanas and urban whites but in some instances also between rural Tswanas and urban Tswanas. During the cold pressor test, the testosterone reactivity and to a lesser extent the prolactin reactivity of the urban Tswanas tended to approach that of the white group as a function of their level of acculturation. All the Tswana groups had a significantly higher plasma renin activity during acute stress than the whites, which could have a bearing on the tendency of urban blacks to develop hypertension.
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society, 1989
A noninvasive continuous arterial blood pressure recording device, Finapres, developed by K.H. We... more A noninvasive continuous arterial blood pressure recording device, Finapres, developed by K.H. Wesseling et al. (1986) was used to investigate cardiovascular reactivity during several experimental stressors. Blood volume as recorded by an infrared plethysmograph is clamped to a set point value by adjusting cuff pressure in parallel with intra-arterial pressure by means of an electro-pneumatic servo-control system. Plotting pressure and
Africa showed a significant increase in cardio/cerebrovascular disease. This study was undertaken... more 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.
Moving from a rural setting to an urban environment is a stressful experience. This situation wil... more Moving from a rural setting to an urban environment is a stressful experience. This situation will most likely result in changes in lifestyle and health. Changes in endocrine reactivity may contribute to the development of western-type diseases in urban communities. In this study it was found that individuals in the process of urbanization exhibit significantly higher endocrine reactivity than rural communities during acutely stressful situations.
Reduced lung function is associated with a risk for the development of cardiovascular disease. Th... more Reduced lung function is associated with a risk for the development of cardiovascular disease. This association may be due to chronic inflammation which is often present in those with reduced lung function. We investigated the possible role of systemic inflammation as the mediator between lung function and arterial stiffness in 1534 black South Africans. Spirometric data including forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were obtained. C-reactive protein (CRP), interleukin-6 (IL-6), blood pressure (BP) and carotid-radial pulse wave velocity (PWV) were determined. In multivariable-adjusted models, an independent inverse association was found between IL-6 and FEV1 (β = -0.20, p < 0.001) and FVC (β = -0.18, p < 0.001). Similar results were found for CRP. PWV was inversely associated with FEV1 (β = -0.06, p = 0.037). No association was found between inflammatory markers, BP or PWV. Reduced lung function was associated with increased inflammation and a...
Reduced lung function is associated with a risk for the development of cardiovascular disease. Th... more Reduced lung function is associated with a risk for the development of cardiovascular disease. This association may be due to chronic inflammation which is often present in those with reduced lung function. We investigated the possible role of systemic inflammation as the mediator between lung function and arterial stiffness in 1534 black South Africans. Spirometric data including forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were obtained. C-reactive protein (CRP), interleukin-6 (IL-6), blood pressure (BP) and carotid-radial pulse wave velocity (PWV) were determined. In multivariable-adjusted models, an independent inverse association was found between IL-6 and FEV1 (β = -0.20, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) and FVC (β = -0.18, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Similar results were found for CRP. PWV was inversely associated with FEV1 (β = -0.06, p = 0.037). No association was found between inflammatory markers, BP or PWV. Reduced lung function was associated with increased inflammation and arterial stiffness. The lack of association between arterial stiffness and inflammatory markers suggests that inflammation may not be the mediating link between lung and vascular function in this population.
The majority of the South African workforce are Africans, therefore potential racial differences ... more 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 hig...
The objectives of this study were to assess dermal exposure of cell workers to nickel at a South ... more The objectives of this study were to assess dermal exposure of cell workers to nickel at a South African base metal refinery and to characterize their skin condition by measuring the skin hydration and trans epidermal water loss (TEWL) indices. The skin hydration index of the index finger, palm, neck, and forehead was measured before, during and at the end of the shift. The TEWL index was measured before and at the end of the shift. Dermal exposure samples were collected with Ghostwipes from the index finger and palm of the dominant hand, before, during, and at the end of the shift. Neck and forehead samples were collected before and at the end of the shift. Wipe samples of various surfaces in the workplace were also collected. Wipes were analyzed for nickel according to NIOSH method 9102, using inductively coupled plasma-atomic emission spectrometry. Hydration indices measured on the hands decreased significantly during the shift, but recovered to normal levels by the end of the shift. TEWL indices for the index finger and palm of the hands are indicative of a low barrier function even before commencement of the shift, which further deteriorated significantly during the shift. During the shift, substantial nickel skin loading occurred on the index finger and palm of the hand. Levels on the neck and forehead were much lower. Various workplace surfaces, which workers come into contact with, were also contaminated with nickel. The skin condition and high levels of nickel on the skin were most probably caused by inadequate chemical protection provided by protective gloves. Although, the permeability of nickel through intact skin is considered to be low, a decreased barrier function of dehydrated or slightly damaged skin will increase its permeability for nickel. The ethnicity of these exposed workers may contribute significantly toward the low incidence of allergic contact dermatitis observed. Several measures to lower dermal exposure to nickel are also recommended.
In this study, we monitored the changes in arterial blood pressure continuously in two groups of ... more 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.
Hairdressers are exposed to numerous hazardous chemical substances, some of which are known or su... more Hairdressers are exposed to numerous hazardous chemical substances, some of which are known or suspected allergens, carcinogens or organic solvents. The objectives of this study were to compare DNA damage and DNA repair capacity between hairdressers with short-term exposure (STE, < 5 years; n = 10), those with longterm exposure (LTE, > 10 years; n = 10), and a control group (n = 11); and to demonstrate that the Comet Assay can be used in biological monitoring to measure the effect of occupational exposure to genotoxic agents in the hairdressing industry. The STE and LTE groups had signifi cantly increased baseline DNA damage compared to the control group. Both the exposed groups also had weaker DNA repair capacity than the control group. The LTE group showed a signifi cantly decreased antioxidant capacity, compared to the control group. Results of this study suggest that the chemicals to which hairdressers are exposed might cause harmful health effects and mutagenic changes.
Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxi... more 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.
ABSTRACT Cardiovascular effects of several physical and psychological stressors were investigated... more ABSTRACT Cardiovascular effects of several physical and psychological stressors were investigated. Indirect continuous blood pressure as well as heart-rate were recorded. Systolic, diastolic, and mean blood pressure as well as heart-rate were recorded. Different patterns of cardiovascular activation during different stressors were obtained. The Valsalva manoeuvre evoked a basic negative feedback baro-receptor response. Physical exercise (bicycle ergometer stress) evoked an overriding of the baro-reflex sympathetic stimulation to fulfil metabolic needs. Psychological stressors such as a TV-game (‘space invaders’), a binary choice program and mental arithmetic produced a pattern of autonomic nervous stimulation which can be described as extra-metabolic or psychophysiological. Possible differences in reaction patterns between psychological stressors are discussed in the light of a literature study. ‘Active’ and ‘passive’ coping may be of importance.
Blacks in an urban environment seem to be more vulnerable to excessive increases in blood pressur... more 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. 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. After resting blood pressure was recorded with a Finapres apparatus, and cardiac output, stroke volume, heart rate, and total peripheral vascular r...
Refinery workers are exposed to many metals, including cobalt and nickel, both of which are skin ... more 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.
The cold pressor test has been widely used in previous cardiovascular reactivity studies as a pre... more The cold pressor test has been widely used in previous cardiovascular reactivity studies as a predictor of hypertension. However, the influence of the physical adaptations of the arterial wall with increasing age on reactivity has not been delineated. 64 men divided into 5 different age groups participated in a laboratory protocol consisting of submerging one hand in ice water for one minute while changes in blood pressure were continuously measured. The results indicated that with increasing age, the systolic blood pressure change, especially the rate of change (slope) is more pronounced than changes in diastolic blood pressure. With increasing age, there is a shift from a diastolic blood pressure reactivity pattern to a more systolic blood pressure reactivity pattern during application of the cold pressor test. This could be ascribed to a decrease in arterial compliance.
Urbanization is a worldwide phenomenon and is most often accompanied by an increased prevalence o... more Urbanization is a worldwide phenomenon and is most often accompanied by an increased prevalence of western-type diseases like hypertension. The higher cardiovascular reactivity (CVR) of black people compared to white people during passive coping stressors has often been linked to their greater vulnerability to hypertension. Blacks, however, display a lower CVR than whites during active coping stressors. In this study it was found that urban blacks show a higher CVR than whites during a passive coping stressor and a lower CVR than whites during an active coping stressor. However, rural blacks consistently show much higher CVR than either whites or urban blacks during both active and passive coping stressors. It seems that CVR is not only a function of the type of stressor applied but can be altered significantly by environmental factors like those experienced during urbanization.
Urbanization is a world-wide phenomenon and results in a radical and sometimes total change in li... more Urbanization is a world-wide phenomenon and results in a radical and sometimes total change in living conditions. This process is accompanied by a significant increase in the incidence of western-type diseases virtually unknown in traditional rural communities. Especially in a multicultural society like South Africa, rural people moving to the city will experience cultural shock leading in many cases to a large degree of acculturation. In this study the effect of acculturation on endocrine reactivity was studied in a population of Tswanas. It was found that significant differences in endocrine reactivity exist not only between rural Tswanas and urban whites but in some instances also between rural Tswanas and urban Tswanas. During the cold pressor test, the testosterone reactivity and to a lesser extent the prolactin reactivity of the urban Tswanas tended to approach that of the white group as a function of their level of acculturation. All the Tswana groups had a significantly higher plasma renin activity during acute stress than the whites, which could have a bearing on the tendency of urban blacks to develop hypertension.
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society, 1989
A noninvasive continuous arterial blood pressure recording device, Finapres, developed by K.H. We... more A noninvasive continuous arterial blood pressure recording device, Finapres, developed by K.H. Wesseling et al. (1986) was used to investigate cardiovascular reactivity during several experimental stressors. Blood volume as recorded by an infrared plethysmograph is clamped to a set point value by adjusting cuff pressure in parallel with intra-arterial pressure by means of an electro-pneumatic servo-control system. Plotting pressure and
Africa showed a significant increase in cardio/cerebrovascular disease. This study was undertaken... more 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.
Moving from a rural setting to an urban environment is a stressful experience. This situation wil... more Moving from a rural setting to an urban environment is a stressful experience. This situation will most likely result in changes in lifestyle and health. Changes in endocrine reactivity may contribute to the development of western-type diseases in urban communities. In this study it was found that individuals in the process of urbanization exhibit significantly higher endocrine reactivity than rural communities during acutely stressful situations.
Reduced lung function is associated with a risk for the development of cardiovascular disease. Th... more Reduced lung function is associated with a risk for the development of cardiovascular disease. This association may be due to chronic inflammation which is often present in those with reduced lung function. We investigated the possible role of systemic inflammation as the mediator between lung function and arterial stiffness in 1534 black South Africans. Spirometric data including forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were obtained. C-reactive protein (CRP), interleukin-6 (IL-6), blood pressure (BP) and carotid-radial pulse wave velocity (PWV) were determined. In multivariable-adjusted models, an independent inverse association was found between IL-6 and FEV1 (β = -0.20, p < 0.001) and FVC (β = -0.18, p < 0.001). Similar results were found for CRP. PWV was inversely associated with FEV1 (β = -0.06, p = 0.037). No association was found between inflammatory markers, BP or PWV. Reduced lung function was associated with increased inflammation and a...
Reduced lung function is associated with a risk for the development of cardiovascular disease. Th... more Reduced lung function is associated with a risk for the development of cardiovascular disease. This association may be due to chronic inflammation which is often present in those with reduced lung function. We investigated the possible role of systemic inflammation as the mediator between lung function and arterial stiffness in 1534 black South Africans. Spirometric data including forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were obtained. C-reactive protein (CRP), interleukin-6 (IL-6), blood pressure (BP) and carotid-radial pulse wave velocity (PWV) were determined. In multivariable-adjusted models, an independent inverse association was found between IL-6 and FEV1 (β = -0.20, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) and FVC (β = -0.18, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Similar results were found for CRP. PWV was inversely associated with FEV1 (β = -0.06, p = 0.037). No association was found between inflammatory markers, BP or PWV. Reduced lung function was associated with increased inflammation and arterial stiffness. The lack of association between arterial stiffness and inflammatory markers suggests that inflammation may not be the mediating link between lung and vascular function in this population.
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