Simultaneous measurement of free-living energy expenditure by the doubly labeled water method and heart-rate monitoring.

Total energy expenditure (TEE) was measured simultaneously in 14 free-living adults over 15 d by the doubly labeled water (DLW) method and for 2-4 separate days by heart-rate (HR) monitoring. Individual curves for HR vs oxygen consumption (VO2) were obtained and an HR (FLEX HR: 97 +/- 8 beats/min, range 84-113 beats/min) that discriminated between rest and activity was identified. Calibration curves were used to assign an energy value to daytime HR above FLEX HR. Below FLEX HR energy expenditure was taken as resting metabolism. Sleeping energy expenditure was assumed to be equal to basal metabolic rate. Average HR TEE (12.99 +/- 3.83 MJ/d) and average DLW TEE (12.89 +/- 3.80 MJ/d) were similar. HR TEE discrepancies ranged from -22.2% to +52.1%, with nine values lying within +/- 10% of DLW TEE estimates. The FLEX HR method provides a close estimation of the TEE of population groups. However, an increased number of sampling days may improve the precision of individual estimates of TEE.

Blood pressure patterns and cardiovascular risk factors in rural and urban gambian communities.

Hypertension is emerging as an important public health problem in sub-Saharan Africa. We studied blood pressure (BP) patterns, hypertension and other cardiovascular risk factors in a rural and an urban area of The Gambia. A total of 5389 adults (> or =15 years) were selected by cluster sampling in the capital Banjul and a rural area around Farafenni. A questionnaire was completed, BP, pulse rate, height and weight were recorded. Glucose was measured 2 h after a 75 g glucose load among participants > or =35 years (n = 2301); total cholesterol, triglycerides, creatinine and uric acid were measured among a stratified subsample (n = 1075). A total of 7.1% of the study participants had a BP > or =160/95 mm Hg; 18.4% of them had a BP > or =140/90 mm Hg. BP was significantly higher in the urban area. BP increased with age in both sexes in both areas. Increasing age was the major independent risk factor for hypertension. Related cardiovascular risk factors (obesity, diabetes and hyperlipidaemia) were significantly more prevalent in the urban area and among hypertensives; 17% of measured hypertensives were aware of this, 73% of people who reported to have been diagnosed as hypertensive before had discontinued treatment; 56% of those who reported being on treatment were normotensive. We conclude that hypertension is no longer rare in either urban or rural Gambians. In the urban site hypertension and related cardiovascular risk factors were more prevalent. Compliance with treatment was low. Interventions aimed at modifying risk factors at the population level, and at improving control of diagnosed hypertension are essential to prevent future increases of cardiovascular morbidity and mortality. In view of limited resources and feasibility of intervention in rural Gambia, these could initially be directed towards urbanised populations.

Effects on birth weight and perinatal mortality of maternal dietary supplements in rural Gambia: 5 year randomised controlled trial .

OBJECTIVE: To test the efficacy in terms of birth weight and infant survival of a diet supplement programme in pregnant African women through a primary healthcare system. DESIGN: 5 year controlled trial of all pregnant women in 28 villages randomised to daily supplementation with high energy groundnut biscuits (4.3 MJ/day) for about 20 weeks before delivery (intervention) or after delivery (control). SETTING: Rural Gambia. SUBJECTS: Chronically undernourished women (twin bearers excluded), yielding 2047 singleton live births and 35 stillbirths. MAIN OUTCOME MEASURES: Birth weight; prevalence of low birth weight (< 2500 g); head circumference; birth length; gestational age; prevalence of stillbirths; neonatal and postneonatal mortality. RESULTS: Supplementation increased weight gain in pregnancy and significantly increased birth weight, particularly during the nutritionally debilitating hungry season (June to October). Weight gain increased by 201 g (P < 0.001) in the hungry season, by 94 g (P < 0.01) in the harvest season (November to May), and by 136 g (P < 0.001) over the whole year. The odds ratio for low birthweight babies in supplemented women was 0.61 (95% confidence interval 0.47 to 0.79, P < 0.001). Head circumference was significantly increased (P < 0.01), but by only 3.1 mm. Birth length and duration of gestation were not affected. Supplementation significantly reduced perinatal mortality: the odds ratio was 0.47 (0.23 to 0.99, P < 0.05) for stillbirths and 0.54 (0.35 to 0.85, P < 0.01) for all deaths in first week of life. Mortality after 7 days was unaffected. CONCLUSION: Prenatal dietary supplementation reduced retardation in intrauterine growth when effectively targeted at genuinely at-risk mothers. This was associated with a substantial reduction in the prevalence of stillbirths and in early neonatal mortality. The intervention can be successfully delivered through a primary healthcare system.

Comparative observations of mucus transport velocity in health and disease.

The present study evaluated mucus transport velocity (MTV) in different areas of the tracheobronchial tree in vitro in normal, acute and chronic bronchitic animals. The average MTV in normal animals ranged from 11.5 mm/min in the trachea to 0.64 mm/min in the pre-terminal bronchus. Chronic bronchitic animals showed mucus hypersecretion, areas of ciliary abnormality and mucus stagnation. The mean transport velocities ranged from 21.2 mm/min in the trachea to 4.1 mm/min in the pre-terminal bronchus. In the acutely ill animals, MTV ranged from 2.5 mm/min in the trachea to zero below the upper lobar bronchus. It is postulated that the higher than normal values in chronic bronchitis are due to altered mucus rheology, increased peristalsis and linear acceleration; whereas those in acute bronchitis were attributed to an early phase of viral or bacterial infection.

Breast-milk IgA and lactoferrin survival in the gastrointestinal tract--a study in rural Gambian children.

The survival of breast-milk secretory-IgA and lactoferrin has been investigated in 23 Gambian children aged 1.5, 3 and 17 months. Endogenous excretion of these immune proteins was measured in 7 weaned 34-month-old children. Defaecation rate was the prime determinant of faecal secretory-IgA and lactoferrin outputs, indicating that partial degradation occurs in the large intestine. Calculations showed that at least 30% of IgA and 2% of lactoferrin ingested from breast-milk must survive in the small intestine. Variations in faecal immune protein outputs were related to differences in intake and defaecation rate and were not affected by age or solid food consumption. The raised faecal outputs of 5 children with diarrhoea were a consequence of their high stool frequencies. IgA disappearance in the large intestine proceeded twice as fast in Gambian breast-fed children as in comparable Cambridge infants, suggesting that differences in gut flora may influence IgA survival. Thus breast-feeding, irrespective of age or additional food, can deliver significant quantities of these antimicrobial proteins to the small intestine but differences in defaecation rate and gut flora may affect their protective potential in the large intestine.

Non-invasive techniques for assessing carbohydrate flux: II. Measurement of deposition using 13C-glucose.

A non-invasive method for studying the dynamics of post-exercise carbohydrate storage by means of whole-body calorimetry and 13CO2 breath tests is described. Seven untrained glycogen-depleted subjects were offered naturally 13C-labelled high carbohydrate meals (97% by energy) at 30 min intervals for 5 h and asked to consume as much as possible. Mean intake averaged 757 +/- 211 (SD) g. Exogenous carbohydrate oxidation over 16 h calculated from gas exchange and isotope ratio measurements averaged 161 +/- 45 g, and endogenous carbohydrate oxidation averaged 31 +/- 25 g. Net carbohydrate storage, calculated as the difference between amount ingested and oxidized, was 563 g which was more than twice the measured hepatic and muscle carbohydrate oxidized during the depletion phase. After correction for body size the major determinant of glycogen storage was the amount of carbohydrate consumed (r = 0.97, P < 0.001) which in turn was determined by each subject's dietary tolerance. Post-repletion exercises (12 h after last meal) were used to remobilize freshly stored glycogen. 13CO2 enrichments indicated that a substantial part of the new glycogen was derived from the exogenous carbohydrate provided by the repletion meals.

Non-invasive techniques for assessing carbohydrate flux: I. Measurement of depletion by indirect calorimetry.

Glycogen forms the smallest yet most labile energy substrate store. Therefore studying carbohydrate flux may be crucial to understanding the regulation of energy balance. Indirect calorimetry has been used to measure carbohydrate oxidation overnight and during exercise in nine fasted subjects. Overnight carbohydrate oxidation (averaging 2.85 +/- 0.8 g h-1) was assumed to be derived primarily from hepatic glycogen since subjects were inactive or asleep, and since glucose oxidized after gluconeogenesis from protein is measured as protein oxidation. Lower-limb muscle glycogen stores were depleted by repeated 30-min periods of cycle ergometry at 45% VO2max until exhaustion (8 +/- 1 periods). The carbohydrate oxidation rate decreased as exercise progressed. Quadratic curves yielded a close fit to each individual's exercise carbohydrate depletion data (mean multiple correlation r = 0.9996) and provided excellent inter-subject discrimination. Total (muscle plus liver) glycogen stores prior to exercise were estimated by extrapolation of the depletion curves to zero oxidation rate. This produced an extrapolation of the depletion curves to zero oxidation rate. This produced an estimate (174 +/- 61 g) which compared well with predictions (208 +/- 43 g) based on reference values for muscle mass and initial glycogen content. The results demonstrate that non-invasive estimates of glycogen status can be obtained from accurate respiratory exchange data.

Breast-milk calcium concentrations during prolonged lactation in British and rural Gambian mothers.

Detailed investigation of breast-milk calcium concentrations during 2 years of lactation have been conducted in Cambridge, UK, and rural Gambia. Mature milk concentrations remained steady for 3 months but declined during months 4-12 by over 25% (p less than 0.001). The pattern was identical in both communities despite differences in breast-feeding practices. Calcium concentrations were not related to feed frequency or breast-milk sodium concentrations, suggesting that breast involution is not responsible for the decrease after 3 months. Breast-milk calcium concentrations were characteristic of the individual, varied twofold between mothers and were independent of maternal age, parity and milk output. Gambian breast-milk contained 19% less calcium than Cambridge milk, throughout lactation (p less than 0.001). The extent to which this reflected the lower calcium intakes of Gambian mothers is unknown. Further studies are required to determine factors regulating breast-milk calcium secretion.

Family history: an opportunity for early interventions and improved control of hypertension, obesity and diabetes.

OBJECTIVE: To examine whether a family history of high-risk groups for major noncommunicable diseases (NCDs) was a significant risk factor for these conditions among family members in a study population in the Gambia, where strong community and family coherence are important determinants that have to be taken into consideration in promoting lifestyle changes. METHODS: We questioned 5389 adults as to any first-degree family history of major noncommunicable diseases (hypertension, obesity, diabetes and stroke), and measured their blood pressure (BP) and body mass index (BMI). Total blood cholesterol, triglyceride, uric acid, and creatinine concentrations were measured in a stratified subsample, as well as blood glucose (2 hours after ingesting 75 g glucose) in persons aged > or = 35 years. FINDINGS: A significant number of subjects reported a family history of hypertension (8.0%), obesity (5.4%), diabetes (3.3%) and stroke (1.4%), with 14.6% of participants reporting any of these NCDs. Subjects with a family history of hypertension had a higher diastolic BP and BMI, higher cholesterol and uric acid concentrations, and an increased risk of obesity. Those with a family history of obesity had a higher BMI and were at increased risk of obesity. Individuals with a family history of diabetes had a higher BMI and higher concentrations of glucose, cholesterol, triglycerides and uric acid, and their risk of obesity and diabetes was increased. Subjects with a family history of stroke had a higher BMI, as well as higher cholesterol, triglyceride and uric acid concentrations. CONCLUSIONS: A family history of hypertension, obesity, diabetes, or stroke was a significant risk factor for obesity and hyperlipidaemia. With increase of age, more pathological manifestations can develop in this high-risk group. Health professionals should therefore utilize every opportunity to include direct family members in health education.

Obesity and undernutrition and cardiovascular risk factors in rural and urban Gambian communities.

OBJECTIVES: This study documented the prevalence of and cardiovascular risk factors associated with obesity and undernutrition in the Gambia. METHODS: Adults (> or =15 years; N = 5373) from rural and urban areas completed a questionnaire; their height, weight, and waist and hip circumferences were measured, and their cardiovascular risk factors were assessed. RESULTS: Prevalence of undernutrition (body mass index < 18 kg/m(2)) was 18.0%; all strata of society were affected. Prevalence of obesity (body mass index > or =30 kg/m(2)) was 4.0% but was higher (32.6%) among urban women 35 years or older. Cardiovascular risk factors were more prevalent among obese participants. CONCLUSIONS: Undernutrition coexists with obesity, demonstrating a "double burden of disease." Differential interventions should focus on high-risk groups; prevention needs a multisectorial approach.

Atopy, intestinal helminth infection and total serum IgE in rural and urban adult Gambian communities.

BACKGROUND: The rarity of atopy in traditional societies has been attributed to high parasite-driven blocking IgE concentrations. Information is lacking on the relationship between atopy, IgE and intestinal helminth infection in African populations. OBJECTIVE: To determine the prevalence of atopy and intestinal helminth infection and to relate these to wheeze history and serum total IgE in a community sample of adults from an urban (Banjul) and a rural (Farafenni) area of the Gambia. METHODS: Six hundred and ninety-three adults were interviewed about respiratory symptoms using a modified version of the IUTLD questionnaire, and had skin prick testing using four allergens. Stools were examined after formol-ether concentration. Total serum IgE concentration was measured in a subset of participants. RESULTS: The prevalence of atopy (mean weal diameter > or = 3 mm) in the urban and rural area was 35.3% and 22.5% (P = 0.05); D. pteronyssinus and Mold mix being the common sensitizing allergens. Prevalence of wheeze in the previous 12 months was 4.4% and 3.5% for the urban and rural areas, respectively. Wheezing was not significantly associated with atopy. Seventeen per cent of urban and 8.2% of rural subjects had helminths detected in stools. There was an inverse association between atopy and intestinal helminth infection; 7% of atopic subjects had helminths, compared to 13% of non-atopic subjects (unadjusted odds ratio 0.51, 95%CI 0.24-1.1, P = 0.09; adjusted odds ratio 0.37, 95%CI 0.15-0.92, P = 0.03). Non-atopics had total serum IgE concentrations about 2.5 times the upper limit of the reference range in non-atopic Western populations. Geometric mean total serum IgE concentration was significantly higher among atopic subjects (570 IU/mL, IQR 91-833) than non-atopic subjects (259 IU/mL, IQR 274-1303) (P < 0.001). IgE concentration was not associated with the presence of helminth infection. CONCLUSION: Further studies are needed to clarify why asthma is still relatively uncommon in spite of the prevalence of atopy in Gambian adults. Our data are also compatible with the idea that atopy might protect against helminth infection.

Asthma, smoking and chronic cough in rural and urban adult communities in The Gambia.

BACKGROUND: Asthma is reported to be rare in traditional rural communities, but is thought to be increasing as lifestyles become more urbanized or 'western'. OBJECTIVES: A community-based survey of non-communicable diseases was conducted from October 1996 to June 1997, and included comparison of the prevalence of asthma, smoking and chronic cough in rural and urban Gambia. METHODS: A cluster sample survey was conducted in a random sample of rural and urban adults (> or = 15 years of age). Subjects were asked about respiratory symptoms using a locally adapted version based on the IULTD questionnaire. Spirometry (basal, methacholine provocation and reversibility with a bronchodilator) and skin prick tests were performed on a randomly selected subsample of all subjects and those who, when interviewed, said they wheezed or had been diagnosed as asthmatic by a doctor. RESULTS: Out of 2166 participants in the urban population, 4.1% reported having had wheezing or whistling in the chest in the previous 12 months, 3.6% reported doctor-diagnosed asthma, and 0.6% chronic cough. In the rural population with 3223 participants these figures were 3.3%, 0.7% and 1.2%, respectively. Wheeze was more common in women, cough for 3 months of the year was more common in the age-groups 45+. Those who reported that they currently smoked accounted for 34% in urban and 42% in rural men. Figures were much lower for women (1.5% and 6.0%). Seven out of 574 randomly selected subjects (1.4%) exhibited bronchial hyper-responsiveness to methacholine challenge. Four of 133 (3.0%) people with self-reported wheeze and 3/69 (4.3%) participants with doctor-diagnosed asthma reacted positively on bronchial provocation with methacholine. There was a remarkably high prevalence of positive skin prick tests to aeroallergens: 38% in participants with a history of wheeze and 27% in those without. CONCLUSION: The prevalence of wheeze (particularly in association with bronchial hyper-responsiveness) was low in both rural and urban Gambia. This is in contrast to the relatively high prevalence of positive skin prick tests to aeroallergens (in both wheezers and non-wheezers), questioning the mechanisms of interaction between allergy and asthma and the presence of protective factors against asthma in this West African population. The high smoking rates justify international concern about tobacco marketing in developing societies.

The use of heart rate monitoring in the estimation of energy expenditure: a validation study using indirect whole-body calorimetry.

1. A modified heart rate (HR) method for predicting total energy expenditure (TEE) was cross-validated against whole-body calorimetry (CAL). Minute-by-minute HR was converted to energy expenditure (EE) using individual calibration curves when HR exceeded a pre-determined 'FLEX' value designed to discriminate periods of activity. ('FLEX' HR was defined as the mean of the highest HR during rest and the lowest HR during the lightest imposed exercise.) Sedentary EE (below FLEX) was calculated as the mean EE during lying down, sitting and standing at rest. Sleeping EE was calculated as basal metabolic rate (BMR) predicted from standard equations. 2. Calibration curves of oxygen consumption v. HR for different postures at rest and during exercise were obtained for twenty healthy subjects (eleven male, nine female); mean r 0.941 (SD 0.04). The mean FLEX HR for men and women were 86 (SD 10) and 96 (SD 6) beats/min respectively. 3. Simultaneous measurements of HR and EE were made during 21 h continuous CAL, which included 4 x 30 min imposed exercise (cycling, rowing, stepping, jogging). HR exceeded FLEX for a mean of 98 (SD 41) min. Mean TEE by CAL (TEE.CAL) was 8063 (SD 1445) kJ. 4. The HR method yielded a mean non-significant underestimate in TEE (TEE.HR) of 1.2 (SD 6.2)% (range -11.4 to +10.6%). Regression of TEE.HR (Y) v. TEE.CAL (X) yielded Y = 0.868 X + 927 kJ, r 0.943, SE of the estimate 458 kJ, n 20. 5. The satisfactory predictive power and low cost of the method makes it suitable for many field and epidemiological applications.

Nationwide prevalence study of hypertension and related non-communicable diseases in The Gambia.

The prevalence of hypertension, diabetes and obesity in The Gambia was assessed in a 1% population sample of 6048 adults over 15 years of age, 572 (9.5%) subjects were hypertensive according to WHO criteria (a diastolic blood pressure (DBP) of 95 mmHg or above and/or a systolic blood pressure (SBP) of 160 mmHg or above); 325 (5.4%) had a DBP of 95 mmHg or above, and 39 (2.3%) a DBP of 105 mmHg or above; 428 (7.1%) had a SBP of 160 mmHg or above. By less conservative criteria (a DBP of 90 mmHg or above and/or SBP of 140 mmHg or above), 24.2% of subjects were hypertensive. The prevalence of hypertension was similar in the major ethnic groups and in urban and rural communities. Age and obesity were risk factors for hypertension; female sex was an additional risk factor for diastolic hypertension. Several communities had a prevalence of diastolic hypertension double the national rate, and significant community clustering of diastolic hypertension (P < 0.01) was confirmed by Monte Carlo methods. Genetic and/or localized environmental factors (such as diet or Schistosoma haematobium infection), may be involved 140 (2.3%) subjects were obese. Obesity was associated with female sex, increasing age, urban environment, non-manual work and diastolic hypertension. Only 14 (0.3%) subjects were found to be diabetic. Hypertension appears to be very prevalent in The Gambia, with a substantial population at risk of developing target organ damage. Further studies to delineate this risk and appropriate interventions to reduce it are needed.

Is there a role for glycosuria testing in sub-Saharan Africa?

BACKGROUND: With increasing urbanization and westernization, rates of diabetes in sub-Saharan Africa (sSA) are likely to rise. Early detection and intervention plays an important role in delaying development of complications. In sSA in particular there is need for an affordable, reliable, safe, feasible test to avert human suffering and exhausting already stressed health facilities. METHODS: Data from two large community-based studies were used to assess the value of glycosuria testing in the detection of diabetes in adults in a sub-Saharan country. A first study (A) tested participants for glycosuria by dipstick; if positive, fasting capillary glucose was measured. A later study (B) measured glucose concentration in venous blood 2 h after a 75-g glucose load; if glycaemia was > or = 10 mmol/l, urine was tested for glycosuria. RESULTS: The positive predictive value of glycosuria for a diagnosis of diabetes (fasting glucose > or = 6.7 mmol/l) was 48%. Sensitivity was 64% (57% if a 2-h-value > or = 10 mmol/l was used as gold standard). Sensitivity was higher among overweight and/or hypertensive subjects, among elderly people in the urban area, and among subjects with higher blood glucose levels. Extrapolated specificity was 99.7%, and the likelihood ratio 190. CONCLUSIONS: Glycosuria testing can identify a considerable number of undiagnosed diabetic patients when specially targeted at high-risk groups (obese, hypertensive, or elderly people). Dipstick glycosuria testing is an appropriate, safe, feasible test for sSA, where the prevalence of diabetes is expected to increase considerably in the near future.