Plasma N terminal pro-brain natriuretic peptide levels and its determinants in a multi-ethnic population.

This study documents the determinants and plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) among hypertensive and normotensive subjects in a multi-ethnic population in the United Arab Emirates (UAE). We obtained demographic, anthropometric and clinical data, together with fasting NT-proBNP and biochemical indices from 128 hypertensive patients and 138 normotensive subjects matched for age, gender and ethnicity. Plasma NT-proBNP levels were significantly (P<0.001), and several-fold higher among hypertensives (median 5.92, inter quartile range (IQR): 1.79-18.48 pmol/l) than normotensives (median 1.78, IQR: 0.59-4.32 pmol/l) in the total study population, and the same was true for the ethnic groups separately. Similarly, plasma levels of glucose, blood urea nitrogen (BUN) and creatinine, but not insulin, were significantly (P<0.05) higher among hypertensives than normotensives. For all subjects combined, log NT-proBNP correlated positively and significantly with age (P<0.01), log glucose (P<0.05), systolic blood pressure (SBP, P<0.001), log BUN (P<0.001) and log creatinine (P<0.001). Multivariate regression analysis showed that NT-proBNP levels were independently and positively correlated with SBP, age, gender, log BUN, Emirati and South East Asian ethnic groups and inversely associated with current exercise. In conclusion, we found circulating levels of NT-proBNP to be significantly increased in hypertensive versus normotensive subjects in the UAE and independently related to SBP, age, gender, indices of renal function and possibly exercise. Our results further suggest a possible modulating effect of ethnicity on NT-proBNP levels.

Predicting proteinuria in hypertensive pregnancies with urinary protein-creatinine or calcium-creatinine ratio.

OBJECTIVE: Evaluate the value of random urinary protein-creatinine (PrCr) and calcium-creatinine (CaCr) ratios to predict 24-h proteinuria in hypertensive pregnancies. STUDY DESIGN: Spot urine samples were collected before routine 24-h urine collections from consecutive pregnant women with hypertension (n=83). Reliability of spot urinary PrCr and CaCr to detect significant proteinuria (>or=300 mg/day) using 24-h urine protein as 'gold-standard' was assessed by receiver-operating characteristic (ROC) curve. RESULTS: Fifty-one patients (61.4%) had significant proteinuria (45 pre-eclampsia, 5 superimposed pre-eclampsia, 1 renal hypertension). Area under ROC curve to predict proteinuria was 0.82 (95% confidence interval (CI) 0.73 to 0.92, P<0.001) for PrCr and 0.55 (95% CI 0.43 to 0.68, P=0.2) for CaCr. A cutoff value of >0.19 for PrCr best predicted significant proteinuria with sensitivity, specificity, positive and negative predictive values and likelihood ratios (positive and negative), respectively, of 80.4, 68.8, 80.4, 68.8%, 2.57 and 3.51. CONCLUSION: Spot urinary PrCr predicts total urinary protein excretion in hypertensive pregnancies.

Hypertension--still an important cause of heart failure?

Hypertension has been the single most important risk factor for heart failure until the last few decades. Now, it is frequently claimed that atherosclerotic coronary artery disease dominates as the major underlying cause, and hypertension is of lesser importance. We here review evidence regarding the contribution of hypertension to heart failure in the recent decades. It is not possible, in our view, to be confident of the relative importance of hypertension and coronary artery disease since there are significant limitations in the available data. The often-questionable diagnostic criteria used in defining heart failure is one such limitation. The absence or inadequacy of blood pressure recordings over the years prior to a diagnosis of heart failure seriously hinders the reaching of firm conclusions in many reports. Extrapolations from aetiological observations in one racial group to those in other racial groups, and from highly selected study groups in tertiary referral centres to patients with heart failure in primary and secondary care, may not be justified. Finally, the situation of heart failure primarily due to impaired left ventricular diastolic function, where hypertension is a frequent precursor, is often ignored in discussions of aetiology. Our view is that hypertension remains and probably is the single most, important modifiable risk factor for cardiac failure in some races and countries, where the dominant cardiac abnormality is left ventricular diastolic dysfunction. The situation is less clear for patients with heart failure primarily due to left ventricular systolic dysfunction.

Association of an apolipoprotein B gene marker with essential hypertension.

We designed an association (retrospective, case control) study aimed at evaluating associations between genetic variations of the human apolipoprotein B (apoB) gene and clinical diagnosis of essential hypertension. Our approach was to compare the distribution of the alleles of a highly polymorphic variable number of tandem repeats localized 3' to the human apoB gene, the apoB 3' hypervariable region (HVR), in a group of normotensive and a group of hypertensive individuals. We collected DNA samples from 437 unrelated nationals (215 normotensives and 222 hypertensives) from the United Arab Emirates (UAEs), and we determined their apoB 3' HVR allele and genotype status with a polymerase chain reaction-based assay. In the UAE population, we found 18 alleles underlying a total of 51 genotypes. The distribution of these alleles was significantly different between normotensive and hypertensive UAE nationals. The main peak of the distributions occurred at 35 repeats among hypertensives (with a relative frequency of 25.7% versus 19.6% in normotensives) and at 37 repeats among normotensives (28.8% versus 20.3% in hypertensives). Alleles with 21, 23, 25, 49, and 55 repeats were found in hypertensives only (with a combined relative frequency of 7.6%). We conclude that variations of the apoB gene, or of a nearby gene, that may be in linkage disequilibrium with these alleles play a role in the development of essential hypertension in the UAEs.

Association study between the ANF gene and hypertension in a Gulf Arab population.

We have studied an insertion/deletion (I/D) dimorphism located in the second intron of the human atrial natriuretic factor (ANF) gene among 232 United Arab Emirates (UAE) nationals (112 normotensives and 120 hypertensives) from the Abu Dhabi Emirate, with a view to evaluating the value of this marker in relation to hypertension. Our findings show that genotype frequencies of this I/D marker occur in Hardy-Weinberg proportions (respective genotype frequencies in the overall sample population are: II, 51%; ID, 42%; DD, 7%). No association, however, was evidenced between this dimorphic site and clinical diagnosis of essential hypertension. This suggests that: 1) this I/D dimorphism is not a useful marker to study the relationship between the ANF gene and hypertension in the UAE; and 2) variations of the ANF gene that may be in linkage disequilibrium with this marker do not play a major role in the determination of hypertension in this Arab population.

Hepatic capillariasis.

The clinico-pathologic features of Capillaria hepatica infection in a 27-year-old Nigerian woman are discussed. This animal parasite has been encountered only rarely in humans. Less than 30 cases of human infection, mostly in children, having been recorded as far as the present authors are aware. This is the first case of hepatic capillariasis reported in West Africa. The pathologic features of this patient is marked by severe hepatic fibrosis, and this is correlated with disordered liver function. The possibility of histopathologic confusion with schistosomiasis mansoni is discussed.

An association study of five genetic loci and left ventricular hypertrophy amongst Gulf Arabs.

We carried out an association (case-control) study of five candidate genes--G-protein beta3 subunit gene variant; methylene tetrahydrofolate reductase (MTHFR); angiotensin converting enzyme (ACE) gene; and paraoxonase 1 and 2 (PON 1 and 2) genes--in a United Arab Emirati population. The aim was to establish a possible relationship between these five candidate genes and clinical left ventricular hypertrophy (LVH) in a genetically homogenous group. DNA samples were collected from 213 unrelated Nationals who were further segregated into 98 subjects with LVH (78 hypertensives and 20 normotensives) and 115 (23 hypertensives and 92 normotensives) age- and sex-matched controls who did not present with LVH. Of the five candidate gene markers studied, no significant differences in the genotype distribution of the MTHFR, PON 1 and 2 or ACE markers were found between the LVH and non-LVH groups. However, a possible association was found between the beta3 G-protein C825T marker and LVH. In conclusion, our results suggest an association between LVH and the C825T allele of the G-protein beta3 subunit gene.

An MboI two-allele polymorphism may implicate the human renin gene in primary hypertension.

As a key enzyme of the renin-angiotensin-aldosterone system, the renin gene (REN) is a good candidate quantitative trait locus that may be implicated in the molecular etiology of essential hypertension. Among mixed reports on the subject, a REN MboI restriction fragment length polymorphism has been shown to be significantly associated with a family history of hypertension in a Japanese population. We show here that the REN MboI dimorphic site is located in the ninth intron of the gene, and we describe a polymerase chain reaction-based assay for detection of this site. We investigated MboI genotype distributions in 331 hypertensive and 279 normotensive subjects from the United Arab Emirates (UAE), a genetically homogeneous ethnic population with no history of smoking or alcohol consumption. A statistically significant association was found between alleles on which the MboI site is present and clinical diagnosis of essential hypertension, indicating that 1) the presence of the MboI site is a marker for susceptibility to hypertension in the UAE (the associated odds ratio is 3.16); and 2) variations of the REN (or of a nearby) gene that may be in linkage disequilibrium with this marker play a role in the development of essential hypertension in the UAE.

Control of epidemic meningococcal meningitis by mass vaccination. I. Further epidemiological evaluation of groups A and C vaccines in northern Nigeria.

Mass vaccination campaigns were mounted by several state governments in the northern Nigerian sector of the African meningitis belt. Bivalent groups A and C polysaccharide vaccines were used. The results of these campaigns in four of the states which are adjacent to each other are presented and assessed. A total of 7535350 persons in the four States, Bauchi, Borno, Gongola and Plateau, were given the vaccine over a period of 4 years (1978-1981). There was a decline in the overall number of cases reported as well as in the number of deaths in the area, where, since 1978, there has not been an epidemic of meningococcal meningitis. Variations were observed among the states which vaccinated over 50% of their populations and had many fewer cases than those which did not. These results show that mass vaccination is an effective means of preventing outbreaks of meningococcal meningitis and may lead to eradication of the disease.

PIP: In mass vaccination campaigns organized by several state governments in northern Nigeria in 1978-81, a total of 7,535,350 people received bivalent groups A and C polysaccharide meningitis vaccines in the states of Bauchi, Borno, Gongola, and Plateau. This figure represents 53% of the population of these 4 states, which are part of the African meningitis belt. Of the total number of reported cases of meningitis from the 4 states in the 1978-81 period, 5565 (80%) occurred in 1978. As more persons were vaccinated over the years, the number of reported cases declined significantly in all states but Gongola, where the percentage vaccinated (19%) was lowest. By 1980 in Bauchi, where 78% of the population had been vaccinated, there were only 12 reported cases of meningitis and no deaths, and there has not been a single reported case of the disease in this state since 1981. These findings confirm the effectiveness of mass vaccination in limiting meningococcal infection. Moreover, mass vaccination has the potential of eradicating the disease, unlike selective vaccination. Epidemiologic research suggests it may be necessary to undertake mass vaccination campaigns only among those 3-15 years of age once every 4-5 years.

Lecithin: cholesterol acyltransfer, dyslipoproteinaemia and membrane lipids in uraemia.

BACKGROUND: Dyslipoproteinaemia is the most important complication linked to the increased morbidity and mortality of uraemic patients from cardiovascular disease. Many factors contribute to the dyslipoproteinaemia, including increased production of very low density lipoproteins (VLDL), decreased lipolysis and impaired low density lipoprotein (LDL) receptor activity. In this study, the role of decreased lecithin:cholesterol acyltransferase (LCAT) activity in relation to plasma and membrane lipid changes is examined. METHODS: Fasted blood samples were taken from 65 uraemic patients, including roughly equal numbers of haemodialysis, peritoneal dialysis and undialysed subjects, and from 29 apparently healthy individuals. Plasma total and free cholesterol, cholesteryl esters (CE), total and individual phospholipids, high density lipoprotein (HDL)-, LDL- and VLDL-cholesterol were all measured, as were erythrocyte and lymphocyte free cholesterol and phospholipids. RESULTS: More than half of all patients, including those both on haemodialysis and peritoneal dialysis, as well as untreated individuals, had relative plasma concentrations of CE below the normal mean - 2SD. These patients had significantly decreased LDL- (2.62 +/- 1.04 compared to 3.61 +/- 0.97 mmol/L; p < 0.001) and HDL-cholesterol (0.71 +/- 0.30 compared to 0.94 +/- 0.27 mmol/L; p < 0.01) and increased VLDL-cholesterol (0.60 +/- 0.50 compared to 0.47 +/- 0.26 mmol/L; p < 0.05) as well as significant increases in membrane cholesterol and cholesterol/phospholipid molar ratio in erythrocytes (3.30 +/- 0.49 and 0.87 +/- 0.08 compared to 2.95 +/- 0.18 mmol/g wet weight and 0.76 +/- 0.04 mol/mol respectively, both p < 0.001) and cholesterol/phospholipid molar ratio of lymphocytes (0.58 +/- 0.14 compared to 0.45 +/- 0.04 mol/mol; p < 0.001). They were markedly deficient in LCAT activity (56.1 +/- 20.4 compared to 105.5 +/- 17.5 nmol/ml/h; p < 0.001). The LCAT activity in plasma of patients with high CE was higher than for those with low CE, but it was also significantly less than normal and this group showed smaller changes in other lipid parameters. CONCLUSIONS: LCAT deficiency is common in uraemia and is associated with changes not just in plasma lipids, but also in membrane lipids which may be relevant to the progression of the disease.

Control of epidemic meningococcal meningitis by mass vaccination. II. Persistence of antibody four years after vaccination.

Meningococcal antibody was measured in 928 persons vaccinated with combined groups A and C polysaccharide antigens in Bauchi State, Nigeria between 1979 and 1982. Protective amounts of antibody were detected by the indirect haemagglutination technique up to 4 years after vaccination. This persistence was observed mainly in adults, although a substantial proportion of older children also had persistent antibody. Titres in younger children fell progressively, and by the third year the mean log2 antibody titre was 1.4; this may not confer protection against disease. A rational policy for vaccination against meningococcal meningitis would be to revaccinate younger children after 2 years, older children after 4 years, and adults after 6-8 or more years.

Morphological changes in the rat kidney following long-term diabetes.

The morphological basis of diabetic nephropathy has been studied using light and electron microscopy. Kidneys of streptozotocin-induced diabetic rats were examined on the light microscope at 4 weeks and 8 months after induction of diabetes mellitus. In addition, the 8-month diabetic kidneys were examined with the electron microscope. Renal hypertrophy was evidenced by the increase in the weight of kidneys of diabetic rats. Whilst the diabetic kidneys were approximately twice as large after 4 weeks they were only 30% larger compared to age-matched controls after 8 months of induction of diabetes. After 4 weeks, light microscopy revealed dilated tubules within the cortex of the diabetic kidneys. Light microscopy showed a significant amount of destruction of the distal convoluted tubules while electron microscopy revealed a spectrum of damage that included basement membrane thickening, loss of podocytic foot processes, disruption of tubular basal infoldings and their related mitochondria and fibrosis of the tubules 8 months after induction of diabetes. It is concluded that renal hypertrophy persists after a prolonged occurrence of diabetes but the extensive damage and loss of renal tissue including the loss of the foot processes of podocytes might be partly responsible for the clinical presentation of diabetic nephropathy.

The angiotensin-converting enzyme (ACE) gene insertion/deletion dimorphism tracks with higher serum ace activities in both younger and older subjects.

BACKGROUND: The absence of a 287 base pair alu sequence in the ACE gene (D allele) is associated with higher ACE levels than its presence (I allele) in adults. We carried out a case-control study of the ACE*I/D dimorphism in relation to circulating ACE activities to evaluate associations between the two variables in adults, compared to younger (18 years or less) individuals. MATERIALS AND METHODS: Genotypes of the ACE*I/D dimorphism were determined on DNA samples from a population of 164 random (unrelated) Emirate nationals, composed of two groups: 112 subjects above 18 years of age (range=20-77 years), and 52 subjects of 18 years or less (range=1-18), and analyzed for putative associations with serum ACE activities. ACE*I/D genotypes of the 164 individuals were determined by assays based on polymerase chain reaction. ACE activities were determined on serum samples of these subjects by colorimetric assays. RESULTS: The D allele was associated with increased ACE values in both adult and younger individuals. Mean ACE activity levels associated with II, ID and DD genotypes, however, were 42%-61% higher in the 18 years and under group of subjects. The ACE*I/D marker accounted for 28% of the variance of the phenomenon determining ACE levels in adults, and for 30% among youngsters. CONCLUSION: The ACE*I/D dimorphism correlated strongly with circulating ACE activities in both adult and young Emirati subjects, and the corresponding mean ACE activities were significantly higher among the youngsters.

Levels of cholesteryl esters and other lipids in the plasma of patients with end-stage renal failure.

BACKGROUND: The importance of plasma lipid abnormalities in chronic renal failure (CRF) is well recognized, but surprisingly little attention has been given to the study of some plasma lipid fractions, including cholesteryl esters (CE) and phospholipids, which might be expected to be important factors in the pathogenesis of the disease. MATERIALS AND METHODS: Fasting blood samples were taken from 25 control subjects and 53 CRF patients (29 predialysis and 24 on hemodialysis). Samples were analyzed for urea nitrogen, creatinine, triacylglycerols, total and individual phospholipids, total and free cholesterol, as well as cholesterol bound to very low-, low- and highdensity lipoproteins (VLDL, LDL and HDL). Plasma CE was calculated and expressed as a percentage of total cholesterol. RESULTS: Over half of the patients had CE levels more than two standard deviations below the control value. In this subgroup of low CE patients, total, LDL- and HDL-cholesterol levels were also significantly lower than for controls, while levels of phosphatidylcholine and lysophosphatidylcholine were decreased and increased, respectively. In patients with high CE, no significant lipid abnormalities were observed. CONCLUSION: In this study, CE was an excellent marker for lipid disturbances--if CE was high, then the other lipid fractions were normal, but if CE was low, most other lipid fractions were abnormal. The changes noted appear to be consequences of or related to deficiency of the plasma enzyme lecithin-cholesterol acyltransferase.