Heritability and genetic correlations of obesity indices with ambulatory and office beat-to-beat blood pressure in the Oman Family Study.

OBJECTIVE: To more precisely and comprehensively estimate the genetic and environmental correlations between various indices of obesity and BP. METHODS: We estimated heritability and genetic correlations of obesity indices with BP in the Oman family study (n = 1231). Ambulatory and office beat-to-beat BP was measured and mean values for SBP and DBP during daytime, sleep, 24-h and 10 min at rest were calculated. Different indices were used to quantify obesity and fat distribution: BMI, percentage of body fat (%BF), waist circumference and waist-to-height ratio (WHtR). SOLAR software was used to perform univariate and bivariate quantitative genetic analyses adjusting for age, age, sex, age-sex and age--sex interactions. RESULTS: Heritabilities of BP ranged from 30.2 to 38.2% for ambulatory daytime, 16.8--21.4% for sleeping time, 32.1--40.4% for 24-h and 22--24.4% for office beat-to-beat measurements. Heritabilities for obesity indices were 67.8% for BMI, 52.2% for %BF, 37.3% for waist circumference and 37.9% for WHtR. All obesity measures had consistently positive phenotypic correlations with ambulatory and office beat-to-beat SBP and DBP (r-range: 0.14--0.32). Genetic correlations of obesity indices with SBP and DBP were higher than environmental correlations (rG: 0.16--0.50; rE: 0.01--0.31). CONCLUSION: The considerable genetic overlap between a variety of obesity indices and both ambulatory and office beat-to-beat BP highlights the relevance of pleiotropic genes. Future GWAS analyses should discover the specific genes both influencing obesity indices and BP to help unravel their shared genetic background.

Oral leukoplakia in the Sudan: clinicopathological features and risk factors.

OBJECTIVES: To analyse the clinical and histopathological features of oral leukoplakia (OL) in the Sudan, and to identify the risk factors associated with dysplastic and malignant changes. METHODS: Records of 117 cases with the diagnosis of OL at the Department of Oral Pathology in the period from 2010 to 2017 were reviewed. RESULTS: Of the 117 cases included in this study, 30 cases (25.6%) showed carcinoma in the initial diagnostic biopsy. The mean age at diagnosis was 59.8 years with a male/female ratio of 3.3:1. The lip (48.7%) and the gingiva (31.6%) were the predominantly affected sites. Multivariate regression analysis revealed that females were associated with 3.36-fold [95% confidence interval (CI), 1.36-10.76; P = 0.012] higher risk of malignant transformation compared with males. Verrucous leukoplakia was associated with 3.38-fold (95% CI,  1.12-10.19; P =  0.031) higher risk of malignant transformation compared with homogeneous leukoplakia. Exclusive Toombak dipping was the significant risk factor for the presence of dysplasia in OL (odds ratio, 9.35; 95% CI, 1.28-67.99; P = 0.027). CONCLUSIONS: Clinical and histopathological features of OL were analysed and correlated. Toombak dipping was the significant risk factor for dysplastic changes, while female gender and verrucous leukoplakia were the factors associated with malignant transformation.

Heritability and genetic and environmental correlations of heart rate variability and baroreceptor reflex sensitivity with ambulatory and beat-to-beat blood pressure.

This family study from Oman (n = 1231) explored the heritability and genetic and environmental correlations of heart rate variability (HRV) and baroreceptor reflex sensitivity (BRS) with ambulatory and beat-to-beat blood pressure (BP). Ambulatory BP was measured for 24 hours to calculate mean values for daytime and sleep separately. Time and frequency domain HRV indices, BRS, office beat-to-beat BP, and heart rate (HR) were measured for 10 minutes at rest. SOLAR software was used to perform univariate and bivariate quantitative genetic analyses adjusting for age, age2, sex, their interactions and BMI. Heritability of SBP and DBP ranged from 16.8% to 40.4% for daytime, sleeping, 24-hour and office beat-to-beat measurements. HR and BRS showed a heritability of 31.9% and 20.6%, respectively, and for HRV indices heritability ranged from 11.1% to 20.5%. All HRV measurements and BRS were found to be negatively correlated with BP, but phenotypic correlation coefficients were relatively weak; HR was positively correlated with BP. None of the genetic correlations were statistically significant while environmental factors explained most of the correlations for all HRV indices with BP. Our study found consistent but weak correlations among HRV, HR, BRS and ambulatory/office beat-to-beat BP. However, environmental rather than genetic factors contributed most to those correlations.

Heritability and genetic correlations of heart rate variability at rest and during stress in the Oman Family Study.

INTRODUCTION: Individual differences in heart rate variability (HRV) can be partly attributed to genetic factors that may be more pronounced during stress. Using data from the Oman Family Study (OFS), we aimed to estimate and quantify the relative contribution of genes and environment to the variance of HRV at rest and during stress; calculate the overlap in genetic and environmental influences on HRV at rest and under stress using bivariate analyses of HRV parameters and heart rate (HR). METHODS: Time and frequency domain HRV variables and average HR were measured from beat-to-beat HR obtained from electrocardiogram recordings at rest and during two stress tests [mental: Word Conflict Test (WCT) and physical: Cold Pressor Test (CPT)] in the OFS - a multigenerational pedigree consisting of five large Arab families with a total of 1326 participants. SOLAR software was used to perform quantitative genetic modelling. RESULTS: Heritability estimates for HRV and HR ranged from 0.11 to 0.31 for rest, 0.09-0.43 for WCT, and 0.07-0.36 for CPT. A large part of the genetic influences during rest and stress conditions were shared with genetic correlations ranging between 0.52 and 0.86 for rest-WCT and 0.60-0.92 for rest-CPT. Nonetheless, genetic rest-stress correlations for most traits were significantly smaller than 1 indicating some stress-specific genetic effects. CONCLUSION: Genetic factors significantly influence HRV and HR at rest and under stress. Most of the genetic factors that influence HRV at rest also influence HRV during stress tests, although some unique genetic variance emerges during these challenging conditions.

Cardio-autonomic functions and sleep indices before and after coronary artery bypass surgery.

BACKGROUND: Earlier studies showed a short-term impairment of cardio-autonomic functions following coronary artery bypass grafting (CABG). There is a lack of consistency in the time of recovery from this impairment. Studies have attributed the post-CABG atrial fibrillation to preexisting obstructive sleep apnea (OSA) without an objective sleep assessment. The aim of this study was to evaluate the effect of CABG on cardio-autonomic and hemodynamic functions and on OSA indices in patients with ischemic heart disease (IHD). METHODS: Cardio-autonomic function using heart rate variability indices, hemodynamic parameters, and sleep studies were performed in 26 patients with stable IHD before, on day-6, and day-30 post-CABG surgery. RESULTS: The high-frequency powers of normalized R-R intervals significantly (P = 0.002) increased from the preoperative value of 46.09 to 66.52 on day-6 and remained unchanged on day-30 postsurgery. In contrary, the low-frequency powers of normalized R-R interval decreased from 53.91 to 33.48 during the same period (P = 0.002) and remained unchanged on day 30 postsurgery. Baroreceptor sensitivity, obstructive and central apnea indices, desaturation index, and lowest O2 saturation were not significantly different between preoperative, day-6, and day-30 postsurgery. CONCLUSION: Our study revealed that recovery of autonomic functions following CABG occurs as early as 30 days of postsurgery. CABG does not seem to have short-term effects on sleep study indices. However, long-term effects need further evaluation.

The Effect of Residing Altitude on Levels of High-Density Lipoprotein Cholesterol: A Pilot Study From the Omani Arab Population.

Lower mortality rates from coronary heart disease and higher levels of serum high-density lipoprotein cholesterol (HDL-C) have been observed in populations residing at high altitude. However, this effect has not been investigated in Arab populations, which exhibit considerable genetic homogeneity. We assessed the relationship between residing altitude and HDL-C in 2 genetically similar Omani Arab populations residing at different altitudes. The association between the levels of HDL-C and other metabolic parameters was also investigated. The levels of HDL-C were significantly higher in the high-altitude group compared with the low-altitude group. Stepwise regression analysis showed that altitude was the most significant factor affecting HDL-C, followed by gender, serum triglycerides, and finally the 2-hour postprandial plasma glucose. This finding is consistent with previously published studies from other populations and should be taken into consideration when comparing cardiovascular risk factors in populations residing at different altitudes.

Reference values for arterial stiffness indices in an Omani Arab population.

OBJECTIVES: To determine the reference values of arterial stiffness indices, particularly augmentation index (AIx) and pulse wave velocity (PWV) using applanation tonometry in a healthy Omani Arab population. METHODS: This prospective study was carried out in the Department of Clinical Physiology, Sultan Qaboos University Hospital, Muscat, Oman over a 2-year period from June 2011 to June 2013. The central AIx, aortic PWV (AoPWV), and central pulse pressure (CPP) were recorded from 120 healthy subjects recruited randomly from a normal population using a SphygmoCor device. The 2.5th and 97.5th percentiles were used to determine the reference ranges for men and women separately. Analyses were performed using univariate statistics. RESULTS: The mean age of the cohort was 38 years for men, and 35 years for women, with the ages ranging from 20-53 years. The overall mean central AIx was 13±11%, and for AoPWV was 6.7±1.6 m/s. The central AIx was higher in women (17 versus 10%; p<0.001), whereas the AoPWV was higher in men (7.1 versus 6.3 m/s; p=0.003). Subjects were categorized according to the gender and age decade, and reference values for CPP, central AIx, and AoPWV were obtained. CONCLUSION: This study reports the reference values for arterial stiffness indices from an Omani Arab population; the results of which should be interpreted in the context of its limitations.

Impaired Fasting Glucose in Omani Adults with no Family History of Type 2 Diabetes.

OBJECTIVES: The aim of this study was to estimate the prevalence of impaired fasting glucose (IFG) among Omani adults with no family history (FH) of diabetes and to investigate the factors behind the risk of developing type 2 diabetes (T2D), while excluding a FH of diabetes. METHODS: A total of 1,182 Omani adults, aged ≥40 years, visited the Family Medicine & Community Health Clinic at Sultan Qaboos University Hospital, Oman, on days other than the Diabetes Clinic days, from July 2010 to July 2011. The subjects were interviewed and asked if they had T2D or a FH of T2D. RESULTS: Only 191 (16%) reported no personal history of T2D or FH of the disease. Of these, anthropometric and biochemical data was complete in 159 subjects. Of these a total of 42 (26%) had IFG according to the American Diabetes Association criteria. Body mass index, fasting insulin, haemoglobin A1C and blood pressure (BP), were significantly higher among individuals with IFG (P <0.01, P <0.05, P <0.01 and P <0.01, respectively). In addition, fasting insulin, BP and serum lipid profile were correlated with obesity indices (P <0.05). Obesity indices were strongly associated with the risk of IFG among Omanis, with waist circumference being the strongest predictor. CONCLUSION: Despite claiming no FH of diabetes, a large number of Omani adults in this study had a high risk of developing diabetes. This is possibly due to environmental factors and endogamy. The high prevalence of obesity combined with genetically susceptible individuals is a warning that diabetes could be a future epidemic in Oman.

Heritability of ambulatory and beat-to-beat office blood pressure in large multigenerational Arab pedigrees: the 'Oman Family study'.

OBJECTIVE: To estimate the heritability of ambulatory blood pressure (BP), heart rate (HR), and beat-to-beat office BP and HR in an isolated, environmentally and genetically homogeneous Omani Arab population. METHODS: Ambulatory BP measurements were recorded in 1,124 subjects with a mean age of 33.8 ± 16.2 years, using the auscultatory mode of the validated Schiller ambulatory BP Monitor. Beat-to-beat BP and HR were recorded by the Task Force Monitor. Heritability was estimated using quantitative genetic analysis. This was achieved by applying the maximum-likelihood-based variance decomposition method implemented in SOLAR software. RESULTS: We detected statistically significant heritability estimates for office beat-to-beat, 24-hour, daytime, and sleep HR of 0.31, 0.21, 0.20, and 0.07, respectively. Heritability estimates in the above mentioned conditions for systolic BP (SBP)/diastolic BP (DBP)/mean BP (MBP)were all significant and estimated at 0.19/0.19/0.19, 0.30/0.44/0.41, 0.28/0.38/0.39, and 0.21/0.18/0.20,respectively. Heritability estimates for 24-hour and daytime ambulatory SBP, DBP, and MBP ranged from 0.28 to 0.44, and were higher than the heritability estimates for beat-to-beat recordings and sleep periods,which were estimated within a narrow range of 0.18-0.21. CONCLUSION: In this cohort, because shared environments are common to all, the environmental influence that occurs is primarily due to the variation in non-shared environment that is unique to the individual. We demonstrated significant heritability estimates for both beat-to-beat office and ambulatory BP and HR recordings, but 24-hour and daytime ambulatory heritabilities are higher than those from beat-to-beat resting levels and ambulatory night-time recordings.

Genome-wide linkage analysis of hemodynamic parameters under mental and physical stress in extended Omani Arab pedigrees: the Oman Family Study.

BACKGROUND: We performed a genome-wide scan in a homogeneous Arab population to identify genomic regions linked to blood pressure (BP) and its intermediate phenotypes during mental and physical stress tests. METHODS: The Oman Family Study subjects (N = 1277) were recruited from five extended families of ~10 generations. Hemodynamic phenotypes were computed from beat-to-beat BP, electrocardiography and impedance cardiography. Multi-point linkage was performed for resting, mental (word conflict test, WCT) and cold pressor (CPT) stress and their reactivity scores (s), using variance components decomposition-based methods implemented in SOLAR. RESULTS: Genome-wide scans for BP phenotypes identified quantitative trait loci (QTLs) with significant evidence of linkage on chromosomes 1 and 12 for WCT-linked cardiac output (LOD = 3.1) and systolic BP (LOD = 3.5). Evidence for suggestive linkage for WCT was found on chromosomes 3, 17 and 1 for heart rate (LOD = 2.3), DBP (LOD = 2.4) and left ventricular ejection time (LVET), respectively. For △WCT, suggestive QTLs were detected for CO on chr11 (LOD = 2.5), LVET on chr3 (LOD = 2.0) and EDI on chr9 (LOD = 2.1). For CPT, suggestive QTLs for HR and LVET shared the same region on chr22 (LOD 2.3 and 2.8, respectively) and on chr9 (LOD = 2.3) for SBP, chr7 (LOD = 2.4) for SV and chr19 (LOD = 2.6) for CO. For △CPT, CO and TPR top signals were detected on chr15 and 10 (LOD; 2.40, 2.08) respectively. CONCLUSION: Mental stress revealed the largest number of significant and suggestive loci for normal BP reported to date. The study of BP and its intermediate phenotypes under mental and physical stress may help reveal the genes involved in the pathogenesis of essential hypertension.

Exercise training attenuates ageing-induced BKCa channel downregulation in rat coronary arteries.

Physical inactivity and ageing are widely recognized as risk factors for development of coronary artery disease. One of the characteristic changes that occurs in aged coronary artery is downregulation of their large-conductance voltage- and calcium-activated K(+) (BK(Ca)) channels. In this study, we investigated the effects of moderate exercise training (ET) on the activity of BK(Ca) channels in coronary arteries of aged rats. Old Fischer 344 rats (23-26 months old) were randomly assigned to sedentary (O-SED, n = 24) or exercise-trained groups (O-ET, n = 28). The O-ET rats underwent a progressive treadmill exercise-training programme for 60 min day(1), 5 days week(1) for 12 weeks. Young animals were used for comparison. Coronary arteries were mounted on a wire myograph, and contractions in response to 1, 10, 30, 50 and 100 nmoll(1) iberiotoxin were compared. Iberiotoxin (100 nmol l(1)) contracted coronary arteries of young, O-SED and O-ET rats by 115 +/- 14, 36 +/- 5.6 and 61 +/- 5% of 5-hydroxytryptamine-induced contractions, respectively. Patch-clamp studies revealed a larger magnitude of BK(Ca) current in young (104 +/- 15.6 pA pF(1)) compared with O-ET (44 +/- 9 pA pF(1)) and least in O-SED coronary smooth muscle cells (8.6 +/- 2 pA pF(1)). Western immunoblotting was performed to study expression levels of BK(Ca) channel proteins. The alpha and beta1 subunits of the BK(Ca) channel were reduced by 40 +/- 3.5 and 30 +/- 2.6%, respectively, in coronary arteries of old compared with young rats, and ET attenuated this reduction in expression level to 28 +/- 2 and 12 +/- 4%, respectively. Our results showed that ageing was associated with a reduction in BK(Ca) channels, and ET partly reversed this reduction. We conclude that low-intensity ET may be beneficial in restoring age-related decline in coronary vasodilatory properties mediated by BK(Ca) channels.

Heritability of hemodynamic reactivity to laboratory stressors in a homogenous Arab population: 'Oman Family Study'.

BACKGROUND: Exaggerated cardiovascular reactivity to stressful stimuli may be a risk factor for the development of hypertension. The genetic influence on blood pressure (BP) reactivity to stress and its control mechanisms has been receiving considerable support. This study aims at examining the heritability of BP and its intermediate hemodynamic phenotypes to acute stress in a homogeneous Arab population. METHODS: Parameters were computed from continuous BP, electrocardiography and impedance cardiography measurements, during rest, word conflict (WCT) and cold pressor (CPT) tests. Heritability estimates (h(2)) were obtained using the variance components-based approach implemented in the SOLAR software package. RESULTS: Reactivity scores for WCT and CPT increased significantly (P < .05) for systolic (SBP), diastolic (DBP), heart rate (HR), cardiac output (CO), and total peripheral resistance (TPR). They decreased significantly (P < .05) for stroke volume (SV), left ventricular ejection time (LVET), end diastolic (EDI) and cardiac contractility (IC) indices. Univariate analysis detected heritability estimates that ranged from 0.19-0.35 for rest, 0.002-0.40 for WCT and 0.08-0.35 for CPT. CONCLUSION: In this unique cohort, resting as well as challenged cardiovascular phenotypes are significantly influenced by additive genetic effects. Heritability estimates for resting phenotypes are in a relatively narrow range, while h(2) for their reactivity is somewhat broader with lower estimates. Further analyses of this study may offer important opportunities for gene finding in hypertension. WHAT IS KNOWN ABOUT THE TOPIC: (1) cardiovascular reactivity to stress predicts cardiovascular disease; (2) genetic susceptibility plays an important role in stress reactivity. Family studies using the cold pressure test reported significant heritability for blood pressure. WHAT THIS STUDY ADDS: (1) this cohort is from five highly consanguineous isolated Arab pedigrees with genetically verified genealogical records and environmental homogeneity; (2) This is the first study to estimate heritability of detailed intermediate hemodynamic phenotypes that make up normal blood pressure.

Effects of overweight and leisure-time activities on aerobic fitness in urban and rural adolescents.

BACKGROUND: The aim of this research was to study the effects of overweight and leisure-time activities on maximal aerobic capacity (VO(2)max) in urban and rural Omani adolescents. METHODS: A total of 529 (245 males, 284 females) adolescents, aged 15-16 years were randomly selected from segregated urban and rural schools. Maximal aerobic capacity was estimated using the multistage 20-meter shuttle-run test. RESULTS: The body mass index (BMI) of urban boys and girls was significantly higher than that of rural boys and girls. Urban boys and girls spent significantly less weekly hours on sports activities and significantly more weekly hours on TV/computer games than their rural counterpart. Urban boys and girls achieved significantly less VO(2)max than rural boys and girls (44.2 and 33.0 vs. 48.3 and 38.6 mL/kg/min, respectively). Maximal aerobic capacity was negatively correlated with BMI in urban boys. CONCLUSION: Overweight and inactivity had significant negative effects on cardiorespiratory fitness in urban boys and girls as compared to their rural counterparts. Weight gain in adolescence requires early intervention.

An audit of the sleep medicine service in Oman.

OBJECTIVE: To audit the sleep service at Sultan Qaboos University Hospital (SQUH), Muscat, Oman, and to explore deficiencies to introduce new measures of improvement. METHODS: Polysomnography (PSG) reports and SQUH medical records of all patients who underwent sleep studies from January 1995 to December 2006 in the sleep laboratory at SQUH were reviewed and analyzed. RESULTS: Out of a total of 1042 sleep studies conducted in the specified period, 768 PSG recordings were valid for analysis. The audit showed that the Otolaryngology Department was the main referring specialty for PSG (43%). Snoring was the main symptom for 33% of the subjects referred, but suspicion of obstructive sleep apnea was the main reason for referral (38%). Three quarters of the patients were males who were also younger, and with lower body mass index compared to females (p=0.0001 for all). Despite large number of patients with an apnea-hypopnea index of >15 (n=261), only 94 (36%) patients received continuous positive airway pressure titrations and treatment. CONCLUSION: The sleep medicine service in SQUH provided the basic service, and raised the awareness of the importance of this specialty. However, substantial effort is required to bring it to international standards.

Differing definition-based prevalence of metabolic syndrome in the women of Oman family study: a function of multiparity.

OBJECTIVE: The aim of this study was to investigate causes of the prevalence of the metabolic syndrome in multiparous Omani Arab women using the International Diabetes Federation definition (IDF). RESEARCH DESIGN AND METHODS: Of 392 married women (mean age 40 years), 354 (90%) were multiparous with an average parity of 8. They were divided into four parity groups: Para 0, Para 1-3, Para 4-6, and Para >6. Body mass index (BMI), waist circumference, fasting, and 2-hour glucose and insulin, plasma lipids, serum leptin, and homeostasis model assessment for insulin resistance (HOMA-IR) and blood pressure (BP) were measured. RESULTS: In the whole cohort, the IDF definition identified 28% women with the metabolic syndrome, whereas it identified 48% in Para >6. In comparison, the National Cholesterol Education Program (NCEP) definition identified 21% and 39%, respectively (kappa = 0.642). Waist circumference was positively associated with the number of live births (beta = 0.78, p = 0.0001). Compared to other individual IDF criteria, only age-adjusted large waist circumference carried the highest risk for having the metabolic syndrome in all groups (odds ratio [OR], 2.3, 95% confidence interval [CI], 1.0-5.4, 3.2, CI, 1.3-8 and 4.8, CI, 2.1-11.2). CONCLUSION: The high prevalence of the metabolic syndrome in multiparous Omani Arab women appeared to be influenced by the parity-related large waist circumference. The high dependency of the IDF criteria on waist circumference for the definition of the metabolic syndrome in this population has led to the misclassification of such women.

Screening of Patients with Snoring and Obstructive Sleep Apnoea using Heart Rate Variability Indices.

OBJECTIVE: Snoring and obstructive sleep apnea (OSA) are common disorders. Snoring associated with excessive daytime sleepiness is the most prevalent symptoms of OSA. Heart rate variability (HRV) is altered in patients with OSA and the degree of alteration may be linked to the severity of OSA. Alterations in HRV in 24 hour tachograms have recently been used in screening OSA patients. Autonomic components causing HRV can be reliably studied using spectral analysis techniques involving fast Fourier transformation (FFT). METHODS: Twenty-three subjects, 13 with severe OSA and 10 controls matched for age and body mass index, were selected from patients who had undergone polysomnography (PSG) for snoring at Sultan Qaboos University Hospital, Oman. A 24- hour electrocardiogram (ECG) Holter recording was done at home, starting at 10am. Spectral analysis of ECG from sleep Holter and PSG recordings was analysed using fast Fourier transformation (FFT). RESULTS: The ECG RR intervals of snorers with OSA were significantly shorter than in snorers without OSA (p<0.01). The low frequency (LF) spectral densities of HRV from polysomnography and Holter were significantly higher in OSA patients than in snorers, (p< 0.0001). The power spectral density of the high frequency bands was similar in the two groups. The overnight ECG Holter accurately identified all 13 snorers with severe OSA. CONCLUSION: The spectral power of the LF band obtained using FFT of sleep HRV from Holter tachograms may be a useful and cost effective test in identifying snorers with severe OSA.

Non-dipping blood pressure in the metabolic syndrome among Arabs of the Oman family study.

OBJECTIVE: The objective was to examine the circadian changes in blood pressure and their relation to the metabolic syndrome and its components in Omani Arabs. RESEARCH METHODS AND PROCEDURES: Ambulatory blood pressure (ABPM) was recorded in 1124 subjects from 5 large, extended, consanguineous, and young Arab pedigrees. According to the International Diabetes Federation's definition, 264 subjects had the metabolic syndrome, a prevalence of 23%. Subjects were defined as non-dippers when their nocturnal systolic blood pressure (SBP) fell by <10% from daytime SBP. RESULTS: Non-dippers with the metabolic syndrome were 131 of 264 (50%), compared with 265 of 860 (31%) without the metabolic syndrome. Of the non-dippers, 99 of 131 (76%) were females and 32 of 131 (24%) were males. Daytime and nighttime SBP and DBP and nighttime pulse pressure were significantly higher in non-dipper subjects with the metabolic syndrome. The important determinants of a non-dipping BP in this cohort were high BMI and high serum triglycerides. DISCUSSION: We hypothesize that obesity and nocturnal volume-dependent hypertension may be involved in the pathophysiology of non-dipping in the metabolic syndrome. This study showed that non-dipping BP was common in subjects with the metabolic syndrome. Higher 24-hour blood pressure load may add to the indices of the overall cardiovascular burden already associated with the metabolic syndrome.

Heritability of determinants of the metabolic syndrome among healthy Arabs of the Oman family study.

The metabolic syndrome, as defined by the International Diabetes Federation, was investigated in five large, extended, highly consanguineous, healthy Omani Arab families of a total of 1277 individuals. Heritability (h2) of the phenotypic abnormalities that make up the syndrome and other related traits was estimated by variance decomposition method using SOLAR software. The overall prevalence of the syndrome was 23%. The prevalence of abnormalities making the syndrome in a descending order were: obligatory waist circumference, hypertension, raised fasting blood glucose, low serum high-density lipoprotein (HDL), and raised serum triglycerides (TGs). Highly significant, but widely spread, h2 values were obtained for: height (0.68), weight (0.68), BMI (0.68), serum HDL (0.63), serum leptin (0.55), percentage body fat (0.53), total serum cholesterol (0.53), fasting serum insulin (0.51), homeostasis model assessment-insulin resistance index (0.48), serum TG (0.43), waist circumference (0.40), diastolic blood pressure (0.38), and 2-hour glucose level (0.17), whereas for the metabolic syndrome itself, h2 was 0.38. The wide spread of h2 results (0.07 to 0.68) indicates that some determinants, such as weight, BMI, and HDL level, are under significant genetic influence among the Omani Arabs. Other determinants such as insulin resistance, abdominal obesity, diastolic blood pressure, and TG levels seem to be more environmentally driven.

Statistical signal characterization for congestive heart failure patient's classification.

This paper aims at investigating a new technique of time-domain analysis of heart variability (R-R interval (RRI)) for the screening of patients with Congestive Heart Failure (CHF). This method is based on the Statistical Signal Characterization (SSC) of the analytical signal that is generated using Hilbert transformation of the RRI data. The four SSC parameters are: amplitude mean, period mean, amplitude deviation and period deviation. These parameters and their maximum and minimum values are determined over sliding segments of 300-samples, 32-samples and 16-samples for both the instantaneous amplitudes and the instantaneous frequencies derived from the analytical signal of the RRI data. Data used in this work are drawn from MIT database. Threshold values used in the identification of CHF patients from normal records are selected using the Receiver Operating Characteristics (ROC) curves on trial data. This new technique correctly classifies 31/33 of trial data and 65/70 of test data.

Long-term exercise training and angiotensin-converting enzyme inhibition differentially enhance myocardial capillarization in the spontaneously hypertensive rat.

OBJECTIVES: To investigate whether combined treatment with lisinopril, an angiotensin-converting enzyme (ACE) inhibitor and exercise training would have an additive effect in enhancing the capillary supply of the left ventricular (LV) myocardium in spontaneously hypertensive rats (SHR). DESIGN: Twelve-week-old male SHR were divided into four groups (10-12 each): sedentary, sedentary treated with lisinopril (15-20 mg/kg per day by gavage), exercise trained, and exercise trained while treated with lisinopril. Exercise training consisted of 1 h a day/5 days a week of running on a treadmill. METHODS: After 10 weeks of experimental protocols, capillary surface density and length density were sterologically determined in 1 mum thick LV tissue samples from perfuse-fixed hearts. RESULTS: Lisinopril significantly reduced systolic blood pressure (SBP) and LV mass in the sedentary with lisinopril and exercise trained with lisinopril groups but did not affect the heart rate (HR). Exercise training did not reduce SBP or LV mass, but significantly reduced HR in the exercise trained and exercise trained with lisinopril groups. Lisinopril treatment (sedentary with lisinopril), exercise training (exercise) and their combination (exercise trained with lisinopril) significantly increased myocardial capillary surface area density by 26, 38 and 65% and length density by 38, 48 and 67%, respectively. CONCLUSION: Lisinopril administration and exercise training independently enhanced myocardial capillarization through a reduction of myocardial mass and stimulation of angiogenesis, respectively. A combination of the two treatments enhanced myocardial capillarization more than either intervention alone. This may aid in the restoration of the normal nutritional status of cardiac myocytes compromised by the hypertrophic state of hypertension.