The prevalence of hypertension in seven populations of west African origin

OBJECTIVES

This study was undertaken to describe the distribution of blood pressures, hypertension prevalence, and associated risk factors among seven populations of West African origin.

METHODS

The rates of hypertension in West Africa (Nigeria and Cameroon), the Caribbean (Jamaica, St. Lucia, Barbados), and the United States (metropolitan Chicago, Illinois) were compared on the basis of a highly standardized collaborative protocol. After researchers were given central training in survey methods, population-based samples of 800 to 2500 adults over the age of 25 were examined in seven sites, yielding a total sample of 10014.

RESULTS

A consistent gradient of hypertension prevalence was observed, rising from 16% in West Africa to 26% in the Caribbean and 33% in the United States. Mean blood pressures were similar among persons aged 25 to 34, while the increase in hypertension prevalence with age was twice as steep in the United States as in Africa. Environmental factors, most notably obesity and the intake of sodium and potassium, varied consistently with disease prevalence across regions.

CONCLUSION

The findings demonstrate the determining role of social conditions in the evolution of hypertension risk in these populations.

ACE, angiotensinogen and obesity: a potential pathway leading to hypertension

The renin-angiotensin system (RAS) plays a crucial role in the regulation of fluid volume, thereby influencing blood pressure (BP). Obesity is an important risk factor for hypertension, however the physiologic basis for this relationship has not been clarified. In a population survey we examined the potential relationship between the RAS and obesity. Based on community sampling, 449 individuals were recruited from metropolitan Kingston, Jamaica. Serum angiotensin-converting enzyme (ACE) and circulating angiotensinogen levels were measured and the associated genes were typed for previously described polymorphisms. Obese individuals (body mass index > 31) had significantly higher serum ACE and angiotensinogen levels, this relationship persisted for ACE in multivariate analyses controlling for BP, hypertension status, age, and gender. The insertion/deletion polymorphism of the ACE gene was associated with variation in the levels of ACE, but inconsistently with body mass index. Variants of the angiotensinogen gene leading to amino acid substitutions at positions 174 and 235 did not influence levels either of angiotensinogen or obesity. These data suggest that obesity may alter the levels of ACE and angiotensinogen, and provide a potential pathway through which obesity leads to elevation of BP.

Simultaneous monitoring of heart rate and motion to assess energy expenditure

Measurement of energy expenditure in free-living individuals represents a methodologic challenge in epidemiologic research. Heart rate monitors, while closely tied to energy expenditure at high levels of energy output, provide much less predictive power at low levels; however, measurement of motion may improve the predictive ability. This study was undertaken to determine the usefulness of simultaneously monitoring heart rate and motion for the estimation of energy expenditure. Ten subjects were studied during simulated activities of daily living (ADLC) and submaximal treadmill tests. Compared to direct measurement, the motion sensor predicted oxygen consumption poorly (r2 = 0.53) for both tests. Heart rate measured simultaneously yielded an r2 of 0.81 for ADLC and 0.90 for the treadmill. Addition of motion data increased the r2 value for the ADLC for all but one individual and increased the group mean from 0.81 to 0.86. This improvement was not observed for the treadmill, confirming the hypothesis that the principle value of monitoring motion occurs at lower heart rates.

Pain following craniotomy: a preliminary study comparing PCA morphine with intramuscular codeine phosphate

We have performed a prospective randomised trial of 30 patients undergoing craniotomy to compare intramuscular codeine phosphate with patient-controlled analgesia using morphine 1 mg bolus with a 10-min lockout and no background infusion. For 24 h postoperatively, pain, nausea, Glasgow coma score, respiratory rate and sedation score were assessed. There was a wide variation in the amounts of morphine requested by the patients in the patient-controlled analgesia group in the first 24 h postoperatively (range 2-79 mg, median 17 mg). There was a small, but non-significant, reduction in pain scores in the patient-controlled analgesia group. There were no significant differences between the two groups in respect of nausea and vomiting, sedation score or respiratory rate. No major adverse effects were noted in either group. Patient-controlled analgesia with morphine is an alternative to intramuscular codeine phosphate in neurosurgical patients which merits further investigation.

Diagnosis of bacterial contact lens related keratitis with the white-light confocal microscope

PURPOSE

We used white-light confocal microscopy to identify the causative organisms in two patients with contact lens related keratitis.

METHODS

The corneal infiltrates were examined by confocal microscopy and corneal specimens were obtained for culture.

RESULTS

In both patients, confocal microscopy revealed 1.5- to 2-micron diameter hyper-reflective bodies below the level of the epithelium. The sizes of these structures were consistent with those of bacteria. The corneal cultures from one patient grew Staphylococcus werneri and the cultures from the other patient grew Streptococcus viridans.

CONCLUSIONS

The confocal microscope permitted the in vivo observation of what we believe to be bacteria in patients diagnosed with contact lens related keratitis.

The role of antimicrobial agents in wound care

This article considers the action of synthetic and natural chemical substances used in the control and destruction of micro-organisms

Patterns of comorbidity and mortality risk in blacks and whites

Comorbidity, the co-existence of multiple chronic conditions in a single individual, has been shown to modify the prognosis of disease states. To estimate disease burdens within and among racial subpopulations of the United States, we examined cross-sectional patterns of comorbidity and their impact on survival using data from the NHANES-1 Epidemiologic Follow-up Study (NHEFS). We considered the occurrence of four cardiovascular conditions: stroke, coronary heart disease, hypertension and diabetes. We summarize the joint occurrence of these four conditions using these different methodologies: the number of conditions occurring in each individual and two summaries that weight the conditions according to their prognostic significance. Using all three methodologies, we found an excess burden of chronic disease in black women as compared with white women. Black men had an excess burden compared to white men for the first two methodologies. However, when we model the relationship of the joint occurrence of the conditions to subsequent mortality, black men and white men are seen to have a similar burden. This similarity of black and white men is due to an interaction between race and prevalent stroke in men that we hypothesize may be due to the small number of black men available for study. Given the apparent conditioning effect of co-existing diseases, it is evident that estimation of disease burdens among groups that differ in terms of health status, in particular among U.S. blacks and whites, requires accounting for the occurrence of multiple chronic diseases. Using either the number of conditions or the prognosis weighted summary, we demonstrated a higher burden of the conditions considered in blacks that in whites in a sample of the U.S. population.

The nurse's role in future cancer services

The Calman report proposes a comprehensive national policy for cancer care. Implementation of these proposals could reduce the inequalities of opportunity of access to specialist services. The future role of nurses in cancer care has still to be clarified.

Standardization of blood pressure measurement in an international comparative study

In the context of a collaborative study on the epidemiology of hypertension in populations of West African origin procedures for standardization of the measurement of blood pressure were evaluated. Comparisons of mean levels of blood pressure, which in large part determine prevalence rates, are highly sensitive to differences in technique. While rotating a single field team may be the ideal approach to multisite studies, it is not practical in international collaborative research. Appropriate techniques to standardize multiple teams over a long period of time have not been well developed, however. In the present study 8981 individuals were examined in eight sites in six countries with the standard mercury sphygmomanometer. An evaluation of the effectiveness of central training, site visits, monitoring of digit preference, and the use of an electronic device for internal standardization is described. In all but one of the sites reliability was high and comparable to the observers at the Coordinating Center. Digit preference for the entire set of measurements was limited (frequency of terminal zero = 23.5% for systolic and 28.9% for diastolic readings) and could be shown to have virtually no effect on prevalence rates or correlation estimates. Mean differences among observers within a given site and between sites were small (+/- 0-5 mmHg). While logistically complex, these methods can provide the basis for standardization in international comparative blood pressure surveys.

The isolation and identification of bacteria from wounds

Wound specimens can be processed in the laboratory in a number of different ways. Routine investigations aim to identify all potential pathogens; a generalised scheme for the procedure is shown in Fig 1.

Pain after craniotomy. A time for reappraisal?

Pain and nausea were prospectively assessed in 52 patients following elective craniotomy. When assessed at 6-hourly intervals the mean pain scores in patients during the first 24 h for all types of craniotomy were relatively low. However, for a period of at least 2 h 18% of patients complained of excruciating pain, 37% of patients complained of severe pain, 29% of patients complained of moderate pain, 4% of patients complained of mild pain and only 12% of patients complained of no pain in the 24 h following craniotomy. The mean dose of codeine phosphate used within the study period was 123 mg (SD 81). No statistically significant differences in severity of pain or use of codeine phosphate were found when comparing patients undergoing craniotomy at different sites. For at least 2 h 37% of patients complained of severe nausea or vomiting, 35% of patients complained of moderate nausea and only 29% of patients reported no symptoms of nausea during the 24-h study period. Again, no statistically significant differences were found in the severity of emetic symptoms when comparing patients undergoing craniotomy at different sites. Contrary to standard assumptions, severe or moderate pain in the first 24 h after craniotomy is common and is poorly treated with codeine phosphate alone.

The prevalence of bacteria and implications for infection control

This article considers the diverse forms of bacteria found in different environments and the measures which need to be considered in the prevention and control of infection

Micro-organisms and wounds

A review of the different types of microscopic organisms that exist in natural environments, particularly those that are commonly implicated in wound infections

Hypertension prevalence, awareness, treatment, and control among African Americans in the 1990s: estimates from the Maywood Cardiovascular Survey

During the last decade, the decline in cardiovascular disease mortality slowed among African Americans, compared to the general population. Hypertension control is likely to play an important role in determining these trends. The Maywood Cardiovascular Survey provides estimates of the prevalence, awareness, treatment, and control of hypertension among African Americans. Between 1991 and 1993, we conducted a cardiovascular disease survey among 1,524 African Americans living in the Chicago suburb of Maywood, Illinois. Estimates of the prevalence, awareness, treatment, and control of hypertension (defined as blood pressure [BP] > or = 140/90 mm Hg or self-reported taking of antihypertensive medications) were calculated and compared to U.S. population estimates for African Americans from NHANES II and III. The prevalence of hypertension in our sample was 32.7% (30.3, 35.1). After age-adjustment to the U.S. population, prevalence was 29.9% (27.9, 31.9), which is nonsignificantly lower than that reported for African Americans in NHANES III (32.4% [30.2, 34.6]). Awareness, pharmacologic treatment, and control on pharmacologic treatment were 81%, 56%, and 55%, respectively. These estimates are, respectively, 15%, 27%, and 42% higher than NHANES II and 7%, 9%, and 11% higher than NHANES III. Nonpharmacologic treatment alone may have accounted for up to 34% of hypertension control overall. Among previously diagnosed hypertensive subjects, risk factors for being untreated were male gender (odds ratio [OR] = 5.3 [1.3, 21.3]) and age < 45 years (OR = 3.8 [1.1, 12.8]), and for being uncontrolled was age > or = 65 years (OR = 1.9 [1.1, 3.0]). Rates of hypertension awareness, pharmacologic treatment, and control on pharmacologic treatment are higher in this sample of African Americans than among African Americans in NHANES II and are comparable to those in NHANES III. The impact of nonpharmacologic treatments on control needs further consideration. Medical Subject Headings (MeSH): hypertension, nonpharmacologic treatment, African-American males.

Xenogeneic expression of human stem cell factor in transgenic mice mimics codominant c-kit mutations

Mutations of c-kit, which encodes a transmembrane receptor tyrosine kinase, have been identified in mice by abnormal coat color, anemia, and germ cell defects. Mice heterozygous for mutations of c-kit have a white forehead blaze and a white ventral spot, leading these mutants to be termed dominant White spotting (W). We have previously demonstrated that the membrane-associated isoform of human stem cell factor (hSCF220, the ligand for c-kit) is inefficiently processed in murine stromal cell transfectants. Thus, in murine cell lines analyzed in vitro, hSCF220 transfectants present SCF as a membrane restricted protein in contrast to the murine SCF220 cDNA protein product, which is slowly cleaved and secreted. We show here that transgenic mice expressing the human SCF220 isoform in vivo display a phenotype indistinguishable from some alleles of W. Specifically, hSCF220-expressing transgenic mice display a prominent forehead blaze and a white ventral spot. Generations of doubly heterozygous animals that carry both a mutated c-kit allele and the hSCF220 transgene display a more severe coat color abnormality. This phenotype appears to be due to occupancy of murine c-kit by human SCF and diminished cell surface expression of endogenous murine SCF. Normal signaling events that lead to cell survival or proliferation appear to be disrupted in vivo in these transgenic mice.

Serotonin-induced increases in platelet cytosolic calcium concentration in depressed, schizophrenic, and substance abuse patients

Exaggerated intracellular calcium responses to challenges with serotonin (5-HT) have been reported in depression. In our studies, consistent with previous reports, patients with depression exhibited an exaggerated increase in 5-HT-stimulated intracellular calcium concentration ([Ca++]i). Basal cytosolic calcium was elevated in both calcium-free and 1 mM calcium media in depressed patients. the increased responsiveness to 5-HT was seen in both conditions. Patients with schizophrenia and substance abuse did not differ from normal controls. The 5-HT response was correlated with diastolic blood pressure (r = 0.33, p = 0.02): however, this association did not fully account for the exaggerated [Ca++]i responses in the depressed group. These findings suggest that exaggerated increases in [Ca++]i in response to serotonin are a characteristic of depressed patients not shared with schizophrenic and substance abuse patients. The relationship of depression to hypertension, two conditions that share abnormalities of calcium homeostasis, warrants further study.

A comparative study of hypertension prevalence, awareness, treatment and control rates in St Lucia, Jamaica and Barbados

BACKGROUND

Cardiovascular diseases represent the most common cause of death in the English-speaking Caribbean, and hypertension represents the most important predisposing condition. However, direct between-country comparative studies in the Caribbean have not previously been undertaken.

OBJECTIVE

To obtain estimates of hypertension prevalence, awareness, treatment and control in three countries in the Caribbean.

DESIGN

Population-based samples of adults aged 25-74 years in St Lucia, Barbados and Jamaica were surveyed regarding their cardiovascular health and their blood pressures were measured using a highly standardized protocol. A reference site was available from a collaborative study among blacks in metropolitan Chicago, Illinois, USA.

RESULTS

At the 160/95 mmHg threshold, age-adjusted hypertension prevalence estimates for Jamaica, St Lucia and Barbados were 17.5, 18.3 and 21.5%, respectively, and 24.7, 26.9 and 27.9%, respectively, at the 140/90 mmHg threshold. The corresponding estimate for the Chicago site at the 140/90 mmHg threshold was 33.2%. The gradient in prevalence resembled the gradient in body mass index (25.7 kg/m2 in Jamaica to 29.3 kg/m2 in the USA). At the 160/95 mmHg threshold, the proportion of all hypertensives who were aware of their disease, pharmacologically treated and controlled was highest in Barbados (90, 85 and 72%, respectively) and lowest in St Lucia (74, 59 and 35%, respectively). Men, particularly those aged less than 55 years, were less likely to have their hypertension treated and controlled.

CONCLUSIONS

Compared with estimates from earlier independent surveys, considerable progress has been made in hypertension detection and control in these countries, which should lead to sizable reductions in the burden of cardiovascular disease.

Polymorphisms of renin-angiotensin genes among Nigerians, Jamaicans, and African Americans

Within the context of an international collaborative study of the evolution of hypertension in the black diaspora, we determined the allelic distribution of hypertension candidate genes for the renin-angiotensin system in three populations of African origin. The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) and the M235T and T174M variants of the angiotensinogen (AGT) gene were examined in individuals from Nigeria, Jamaica, and the United States. Large differences in the prevalence of hypertension were recorded in door-to-door surveys, ranging from 16% in Nigeria to 33% in the United States. The frequency of the D allele was similar in all groups (54%, 59%, and 63% in Nigeria, Jamaica, and the United States, respectively). The 235T allele of the AGT gene was found in 81% of US and Jamaican blacks and 91% of Nigerians; very little variation was seen for the T174M marker. Despite large differences in hypertension rates, genetic variation at the index loci among these groups was modest. Overall, the frequency of the ACE*D allele was only slightly higher than that reported for European and Japanese populations, whereas the AGT 235T allele was twice as common. Compared with blacks in the western hemisphere, Nigerians had a higher frequency of the 235T allele, which is consistent with 25% European admixture in Jamaica and the United States. The results indicate the potential for etiologic heterogeneity in genetic factors related to hypertension across ethnic groups while suggesting that environmental exposures most likely explain the gradient in risk in the comparison among black populations.

Angiotensinogen and blood pressure among blacks: findings from a community survey in Jamaica

OBJECTIVE

To examine the association between blood pressure, angiotensinogen levels, angiotensin converting enzyme activity and polymorphisms of the angiotensinogen and angiotensin converting enzyme genes in a population-based sample.

METHOD

Five hundred participants were recruited in a house-to-house survey of three communities in metropolitan areas of Kingston and St Andrew, in Jamaica. Demographic data, anthropometric and blood pressure measurements were obtained for each participant during a brief clinic visit. Circulating levels of angiotensinogen and angiotensin converting enzyme activity were measured in venous blood samples. Polymorphisms of the angiotensinogen and angiotensin converting enzyme genes were determined.

RESULTS

A weak association between angiotensinogen level, angiotensin converting enzyme activity and blood pressure was identified in this population, but substantial joint effect of angiotensin converting enzyme activity and angiotensinogen level on blood pressure was apparent. Variants of the angiotensinogen gene had inconsistent effects on blood pressure and on the risk of hypertension. Angiotensinogen level and angiotensin converting enzyme activity were significantly related to several measures of obesity, including body mass index, waist circumference and skin fold thickness.

CONCLUSION

The angiotensinogen and angiotensin converting enzyme genetic variants which were studied appear to have only a modest relationship with blood pressure and associated anthropometric risk factors among blacks.

Use of a type-III trilateral external skeletal fixation device in three deer with comminuted fractures

A type-III trilateral external skeletal fixation device was used to repair comminuted fractures of metacarpal and tibial bones in 3 deer. Mean weight of the deer was 25 kg, and mean age was 4 months. Mean interval from application until removal of the device was 6.5 weeks. All deer had complete function of their previously fractured limbs and had minimal complications during healing. Several factors should be considered when choosing a method of repair for wildlife with fractured limbs. Economic constraints and demeanor of the animal may limit the number of options. Analysis of results of our findings indicated that type-III trilateral external skeletal fixation devices can be used for the repair of comminuted fractures in young deer.