Age-Group-Specific Associations between the Severity of Obstructive Sleep Apnea and Relevant Risk Factors in Male and Female Patients

Aim

To seek accurate and credible correlation manner between gender, age, and obesity; and the severity of obstructive sleep apnea (OSA) in large-scale population.

Methods

Totals of 1,975 male and 378 female OSA patients were sequentially recruited. Centralized covariant tendencies between age, body mass index (BMI), and waist hip ratio (WHR); and OSA severity, were explored in a gender-specific manner via multiple statistical analyses. The accuracies of observed correlations were further evaluated by adaptive multiple linear regression.

Results

All of age, BMI, WHR, smoking, drinking, and OSA severity differed between males and females. BMI and WHR were positively and (approximately) linearly associated with OSA severity in both males and females. Restricted cubic spline analysis was more effective than was the Pearson correlation approach in correlating age with AHI, and provided age crossover points allowing further piecewise linear modeling for both males and females. Multiple linear regression showed that increasing age was associated with OSA exacerbation in males aged ≤40 years and in females aged 45–53 years. BMI, WHR, and diabetes were independently associated with OSA severity in males with age-group-specific pattern. In females, only BMI was associated with OSA severity at all ages.

Conclusions

In male patients, BMI and WHR are prominent risk factors for OSA exacerbation. Age and diabetes are associated with OSA severity in males of particular ages. In females, BMI is also a prominent risk factor for severe OSA, and OSA severity increased with age in the range 45–53 years.     

Hypertension, and blood pressure response to graded exercise in young obese and non-athlethic Nigerian university students.

Hypertension, and the effect of graded exercise on Blood pressure (BP), in 60 obese non-athletic young medical students (40 females and 20 males) with Body Mass Index (BMI) greater than 30 were studied. The subjects were in the age range of 18-22 years with mean age of 20.30 +/-1.32 years. Twenty percent of the males and 7 percent of the females were found to be hypertensives [P < 0.05] and the severity of the hypertension significantly [P < 0.05] increased linearly with increase in BMI (r =0.6). Our study reveals a positive direct correlation between obesity and socioeconomic status and BP. Marked increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), time of return (RT) were observed in the obese individuals compared to control at all levels of graded exercise with the highest rises seen during severe exercise. Among the obese subjects, the increases in BP were more in the males than females, but time of return was higher in females than males. This study further confirms that obese young individuals are prone to early onset of hypertension and thus other cardiovascular diseases and less tolerant to physical exercises. Our results add to the evidence that hypertension is common among obese young adults.     

The autosomal dominant trait of obesity, acanthosis nigricans, hypertension, ischemic heart disease and diabetes type 2.

OBJECTIVE: Among obese subjects, acanthosis nigricans in both males and females is not as uncommon as previously thought. Whereas this finding was extensively evaluated in females, mostly in the context of polycystic ovaries syndrome, little attention has been paid to obese males with acanthosis nigricans. As acanthosis seems to be a marker for insulin resistance, the present study was designed to evaluate the hypothesis that the clinical syndrome of obesity and acanthosis would take a different clinical course than that of simple obesity. METHODS: To characterize the course of acanthosis nigricans and obesity in males, we examined 22 children and adolescents with this complex, together with their parents and grandparents and found them to follow a detrimental sequence of the metabolic syndrome. We compared the findings to 13 age-matched males with obesity but no clinical apparent acanthosis nigricans. We analyzed the clinical course, fat distribution, glucose, insulin and C-peptide and lipoproteins. RESULTS: Onset of obesity in the metabolic syndrome group was at a mean age of 6.4 years, as compared to 2.3 years in the controls. The metabolic syndrome patients had a truncal (android) distribution of fat and their fasting blood glucose was significantly higher. HDL/total cholesterol was lower. Examination of the pedigrees suggested autosomal dominant inheritance of the obesity and acanthosis nigricans complex, extending to hypertension and ischemic heart disease in the parents' generation, and further extending to include diabetes type 2 in the grandparents' generation. CONCLUSIONS: This metabolic syndrome is inherited as an autosomal dominant trait, with onset of truncal obesity at age 6-7 years, acanthosis nigricans during childhood or adolescence, extending to hypertension and ischemic heart disease during young adulthood, and further extending to include diabetes type 2 in late adulthood. It is recommended that such children should be followed up as an 'at-risk' group, and would probably benefit from intensive weight reduction, which may prevent the later manifestations of the syndrome.     

Impact of Hypertension on the Association of BMI with Risk and Age at Onset of Type 2 Diabetes Mellitus: Age- and Gender-Mediated Modifications

Aims

Given that BMI correlates with risk of Type 2 diabetes mellitus (T2DM), and that hypertension is a common comorbid condition, we hypothesize that hypertension augments significantly the impact of obesity on T2DM onset.

Methods

We obtained data on T2DM in Kuwaiti natives from Kuwait Health Network Registry. We considered 1339 comorbid individuals with onset of hypertension preceding that of T2DM, and 3496 non-hypertensive individuals but with T2DM. Multiple linear regressions, ANOVA tests, and Cox proportional hazards models were used to quantify the impact of hypertension on correlation of BMI with age at onset and risk of T2DM.

Results

Impact of increasing levels of BMI on age at onset ot T2DM is seen augmented in patients diagnosed with hypertension. We find that the slope of the inverse linear relationship between BMI and onset age of T2DM is much steep in hypertensive patients (−0.69, males and −0.39, females) than in non-hypertensive patients (−0.36, males and −0.17, females). The decline in onset age for an unit increase of BMI is two-fold in males than in females. Upon considering BMI as a categorical variable, we find that while the mean onset age of T2DM in hypertensive patients decreases by as much as 5–12 years in every higher BMI categories, significant decrease in non-hypertensive patients exists only when severely obese. Hazard due to hypertension (against the baseline of non-hypertension and normal weight) increases at least two-fold in every obese category. While males have higher hazard due to hypertension in early adulthood, females have higher hazard in late adulthood.

Conclusion

Pre-existing condition of hypertension augments the association of BMI with Type 2 diabetes onset in both males and females. The presented results provide health professionals directives on the extent of weight-loss required to delay onset of Type 2 diabetes in hypertensive versus non-hypertensive patients.     

Symptoms and risk for obstructive sleep apnea among sample of Saudi Arabian adults

The aim of this study was to determine the risk and symptoms for obstructive sleep apnea (OSA) among Saudi Arabian adults. This cross-sectional survey among healthy participants was conducted at King Abdulaziz Medical City-Riyadh (KAMC-R). The Berlin Questionnaire (BQ) was used to assess the risk of OSA, and Epworth Sleepiness Scale (ESS) was used to measure excessive daytime sleepiness (EDS) as a manifestation of OSA in participants. The total number of participants was 2095, mean age of the sample was 42.3 (±15.5) years and 848 (40.7%) were females. Using BQ, 31.9% of the participants were classified as high risk for OSA (33.4% among females and 31.1% among males). The risk for OSA increased with age: 19.4% among the young group (≤29 years), 35.2% among the middle-aged (30–59 years), and 41% among the elderly (≥60 years). The risk of symptomatic OSA by combining both BQ and ESS was 7.8% and increased with age (5.5% among the young group, 8.5% among the middle-aged, and 9.7% among the elderly), but there was no difference between gender (8% among females vs. 7.7% among males). This study showed that the risk for OSA is very high, is equal in both genders and it increases with age and obesity.

     

Impact of Cardiovascular Risk Factors on Carotid Intima-Media Thickness and Degree of Severity: A Cross-Sectional Study

Objective

Age, hypertension, dyslipidemia and diabetes are common cardiovascular risk factors (CVRFs) that contribute to the development of atherosclerosis in cardiovascular system including carotid artery disease. However, the impact of these risk factors on the increased carotid intima-media thickness (cIMT) and degree of carotid severity remains to be further clarified. This study aims to evaluate the relationship between CVRFs and degree of carotid severity and cIMT in high-risk subjects.

Methods

Four thousand and three hundred ninety-four subjects with one or more risk factors were retrospectively reviewed in this study. Patients were divided into different groups based on age, the type and quantity of CVRFs. cIMT and degree of carotid artery stenosis were measured and analyzed based on carotid ultrasound imaging with findings compared to the CVRFs to determine the correlation between these variables.

Results

Aging was significantly associated with degree of severity (P < 0.05) and cIMT was significantly increased with age (P < 0.05). Individual CVRF analysis shows that hypertension was more related to the degree of severity than dyslipidemia and diabetes with corresponding abnormal cIMT rates being 79.39%, 72.98% and 32.37%, respectively. The prevalence of carotid atherosclerosis were 20.06%, 22.88% and 28.63%, respectively corresponding to patients with zero, one and more than one chronic diseases. The percentage of abnormal cIMT in hypertensive patient group with dyslipidemia is significantly higher than the other groups (P< 0.05).

Conclusions

This study shows a direct correlation between the degree of carotid severity and cIMT and cardiovascular risk factors, especially with age and hypertension. Carotid atherosclerosis is closely related to the number of cardiovascular risk factors.     

Alcohol, smoking and body build: obesity as a result of the toxic effect of 'social' alcohol consumption

Previous work showed that obesity in the average human male is not due to increased caloric intake. To test the hypothesis that 'social' ethanol consumption causes obesity by a hepatotoxic mechanism, the relationships between alcohol intake, cigarette smoking, serum gamma-glutamyl transpeptidase (GGT) and body build were investigated in 816 adult patients, 491 males and 325 females. A large part of the Broca index variance could be explained by hepatic damage as reflected by the GGT level. The higher the GGT, the more overweight were the subjects. Hyperinsulinemia may be the pathogenetic link; insulin is the strongest known blocker of lipolysis. Almost the total variation of obesity with GGT, however, occurred in the range of GGT up to 25 U/l, which is usually, but nevertheless erroneously, considered to be the normal range. This effect was independent of sex and age. Normal GGT is below 10 U/l, which is found on average in females aged less than 20 years. Females tolerate less alcohol than males. Although GGT is as high in females as in males around age 30, males drink about three times as much ethanol. For the same GGT the Broca index is significantly higher in females than in males. GGT generally increases with age; maximum GGT is reached in females in the age group 21-40 years (due to the change in drinking habits around 1968), declining thereafter; in males at age 50. Obesity per se is not correlated with a high GGT. In the females there are hormonal factors influencing obesity. Although in the females GGT decreases on average after age 40, obesity increases (due to the decrease in estrogens). After age 50 ethanol tolerance in males decreases: they reduce their alcohol consumption, and yet the GGT remains high. -Cigarette smoking is a factor which independently influences obesity. Although people who smoke tend also to drink more alcohol, smokers are significantly leaner than nonsmokers. On average males smoke about twice as heavily as females; this contributes to the fact that on average males are leaner than females despite their higher alcohol consumption. Due to lower consumption the influence of ethanol and smoking on body build is smaller in females than in males.     

Cumulative Association of Obstructive Sleep Apnea Severity and Short Sleep Duration with the Risk for Hypertension

Obstructive sleep apnea (OSA) and short sleep duration are individually associated with an increased risk for hypertension (HTN). The aim of this multicenter cross-sectional study was to test the hypothesis of a cumulative association of OSA severity and short sleep duration with the risk for prevalent HTN. Among 1,499 patients undergoing polysomnography for suspected OSA, 410 (27.3%) previously diagnosed as hypertensive and taking antihypertensive medication were considered as having HTN. Patients with total sleep time (TST) <6 h were considered to be short sleepers. Logistic regression procedures were performed to determine the independent association of HTN with OSA and sleep duration. Considering normal sleepers (TST ≥6 h) without OSA as the reference group, the odds ratio (OR) (95% confidence intervals) for having HTN was 2.51 (1.35–4.68) in normal sleepers with OSA and 4.37 (2.18–8.78) in short sleepers with OSA after adjustment for age, gender, obesity, diabetes, depression, current smoking, use of thyroid hormones, daytime sleepiness, poor sleep complaint, time in bed, sleep architecture and fragmentation, and study site. The risk for HTN appeared to present a cumulative association with OSA severity and short sleep duration (p<0.0001 for linear trend). The higher risk for HTN was observed in short sleepers with severe OSA (AHI ≥30) (OR, 4.29 [2.03–9.07]). In patients investigated for suspected OSA, sleep-disordered breathing severity and short sleep duration have a cumulative association with the risk for prevalent HTN. Further studies are required to determine whether interventions to optimize sleep may contribute to lower BP in patients with OSA.     

Elements in hair and nails of urban residents of New Delhi

The concentrations of Cd, Cr, Cu, Mn, Ni, Pb, and Zn were estimated in hair and nails of urban residents of New Delhi. Particularly, hair levels of Cu and Mn in hypertensive males, Cr and Zn in hypertensive females, and Zn in CHD and diabetic females, and nail levels of Zn in CHD and hypertensive females were significantly lower than controls. Thus, it is observed that there exists some positive correlation between element levels in hair and nails and CHD, hypertension, and diabetes of these subjects.     

Relationship between Obstructive Sleep Apnea Severity and Sleep,Depression and Anxiety Symptoms in Newly-Diagnosed Patients

Obstructive sleep apnea (OSA) occurs in at least 10% of the population, and leads to higher morbidity and mortality; however, relationships between OSA severity and sleep or psychological symptoms are unclear. Existing studies include samples with wide-ranging comorbidities, so we assessed relationships between severity of OSA and common sleep and psychological disturbances in recently diagnosed OSA patients with minimal co-morbidities. We studied 49 newly diagnosed, untreated OSA patients without major co-morbidities such as mental illness, cardiovascular disease, or stroke; subjects were not using psychoactive medications or tobacco (mean ± std age: 46.8±9.1 years; apnea/hyponea index [AHI]: 32.1±20.5 events/hour; female/male: 12/37; weight <125 kg). We evaluated relationships between the AHI and daytime sleepiness (Epworth Sleepiness Scale; ESS), sleep quality (Pittsburg Sleep Quality Index; PSQI), depressive symptoms (Beck Depression Inventory-II; BDI), and anxiety symptoms (Beck Anxiety Inventory; BAI), as well as sex and body mass index (BMI). AHI was similar in females and males. Mean levels of all symptoms were above normal thresholds, but AHI was not correlated with age, ESS, PSQI, BDI, or BAI; only BMI was correlated with OSA severity. No differences in mean AHI appeared when subjects were grouped by normal versus elevated values of ESS, PSQI, BDI, or BAI. Consistent with other studies, a strong link between OSA severity and psychological symptoms did not appear in these newly diagnosed patients, suggesting that mechanisms additional to the number and frequency of hypoxic events and arousals occurring with apneas contribute to adverse health effects in OSA. OSA patients presenting with mild or moderate severity, and no major co-morbidities will not necessarily have low levels of sleep or psychological disturbances.     

Association of Central Obesity With the Severity and Audiometric Configurations of Age‐related Hearing Impairment

To investigate the effect of central obesity on the severity and characteristics of age‐related hearing impairment (ARHI), we recruited 690 adult subjects with normal or symmetrical sensorineural hearing loss (SNHL). The effects of age, gender, morphometry, habits, systemic diseases, and environmental noise exposure on average pure tone hearing level at low frequencies (pure tone audiometry (PTA)‐low) and high frequencies (PTA‐high) were analyzed. After adjusting for age, gender, systemic disease, and other variables, waist circumference (WC) showed a significant positive association with PTA‐low and PTA‐high. In females, PTA‐low and PTA‐high only showed significant positive association with age, but not with WC or other variables. However, PTA‐high showed a positive association with borderline significance with WC in female subjects older than 55. In males, WC as well as age and noise exposure showed significant positive associations with both PTA‐low and PTA‐high, primarily in subjects younger than 55. When both WC and BMI were taken into account in a backward stepwise multivariate linear regression analysis, WC, but not BMI, showed a significant positive association with PTA‐low and PTA‐high in males younger than 55, and with PTA‐high with borderline significance in females older than 55. However, the audiogram patterns were not significantly affected by central obesity in either age or gender. Our results suggest that WC was, even after adjustment for BMI, an independent risk factor of ARHI, particularly for low and high frequencies in males younger than 55 and for high frequencies in female subjects older than 55.     

The Associations between Anthropometric Indices and Obstructive Sleep Apnea in a Korean Population

Background

Obesity is a major risk factor for the development of obstructive sleep apnea (OSA). Although clinical and epidemiological studies have shown that OSA and obesity are strongly associated, few Asian studies have examined the associations between anthropometric obesity indices and OSA, especially in the Korean population. The purpose of this study was to evaluate the influence of anthropometric obesity indices on OSA in a Korean population.

Methods

Anthropometric indices, including neck circumference, waist circumference, and body mass index, were assessed in 383 consecutive subjects with suspected OSA.

Results

Of the 383 subjects assessed, 316 (82.5%) were diagnosed with OSA. Neck circumference (r = 0.518), waist circumference (r = 0.570), and body mass index (r = 0.512) were correlated with the apnea-hypopnea index (p<0.001, for all). After adjusting for age, sex, alcohol consumption, and smoking, a logistic regression model showed that neck circumference [odds ratio (OR), 1.414; p<0.001)], waist circumference (OR, 1.114; p<0.001), and body mass index (OR, 1.364; p<0.001) were associated with OSA. The linear regression model showed that neck circumference (β = 3.748, p<0.001), waist circumference (β = 1.272, p<0.001), and body mass index (β = 3.082, p<0.001) were associated with apnea-hypopnea index. The cut-off values for predicting OSA were determined as 34.5 cm for neck circumference, 76.5 cm for waist circumference, and 23.05 kg/m² for body mass index for females, and 38.75 cm for neck circumference, 88.5 cm for waist circumference, and 24.95 kg/m² for body mass index for males.

Conclusion

Increased anthropometric indices were significantly associated with the presence and severity of OSA in a Korean population. In addition, this study demonstrated the cut-off values for body mass index, waist circumference, and neck circumference for increased OSA risk.     

Heart Rate Responses to Autonomic Challenges in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is accompanied by structural alterations and dysfunction in central autonomic regulatory regions, which may impair dynamic and static cardiovascular regulation, and contribute to other syndrome pathologies. Characterizing cardiovascular responses to autonomic challenges may provide insights into central nervous system impairments, including contributions by sex, since structural alterations are enhanced in OSA females over males. The objective was to assess heart rate responses in OSA versus healthy control subjects to autonomic challenges, and, separately, characterize female and male patterns. We studied 94 subjects, including 37 newly-diagnosed, untreated OSA patients (6 female, age mean±std: 52.1±8.1 years; 31 male aged 54.3±8.4 years), and 57 healthy control subjects (20 female, 50.5±8.1 years; 37 male, 45.6±9.2 years). We measured instantaneous heart rate with pulse oximetry during cold pressor, hand grip, and Valsalva maneuver challenges. All challenges elicited significant heart rate differences between OSA and control groups during and after challenges (repeated measures ANOVA, p<0.05). In post-hoc analyses, OSA females showed greater impairments than OSA males, which included: for cold pressor, lower initial increase (OSA vs. control: 9.5 vs. 7.3 bpm in females, 7.6 vs. 3.7 bpm in males), OSA delay to initial peak (2.5 s females/0.9 s males), slower mid-challenge rate-of-increase (OSA vs. control: −0.11 vs. 0.09 bpm/s in females, 0.03 vs. 0.06 bpm/s in males); for hand grip, lower initial peak (OSA vs. control: 2.6 vs. 4.6 bpm in females, 5.3 vs. 6.0 bpm in males); for Valsalva maneuver, lower Valsalva ratio (OSA vs. control: 1.14 vs. 1.30 in females, 1.29 vs. 1.34 in males), and OSA delay during phase II (0.68 s females/1.31 s males). Heart rate responses showed lower amplitude, delayed onset, and slower rate changes in OSA patients over healthy controls, and impairments may be more pronounced in females. The dysfunctions may reflect central injury in the syndrome, and suggest autonomic deficiencies that may contribute to further tissue and functional pathologies.     

Body fat distribution has no effect on serum visfatin levels in healthy female subjects

Obesity is the presence of either abnormal absolute amount or relative proportion of body fat. Contrary to gluteal obesity, visceral obesity is associated with different metabolic alterations including insulin resistance (IR). A relatively new adipocytokine visfatin is shown to be expressed predominantly in visceral fat and exhibit insulin-mimicking effects in rodents. It is still unclear whether serum visfatin levels are associated with increased total or visceral fat mass in humans. The aim of our study was to investigate the relation between visfatin and obesity parameters namely body mass index (BMI) and waist circumference (WaC) and IR in healthy female subjects. Eighty one female subjects ?20 years of age, having no diagnosis of glucose intolerance or diabetes, hypertension and dyslipidemia were chosen. The patients were divided into four groups according to their BMI and WaC values. Serum visfatin and HOMA-IR levels did not differ among groups. No correlation was detected between serum visfatin levels and obesity and metabolic parameters. In conclusion, we demonstrated that body fat distribution did not affect serum visfatin levels in healthy female subjects. Further studies are needed to clarify the exact factors influencing and determining serum visfatin levels and its clinical reflections.     

Covariates and prevalence of obesity among adult North Indian population

The present study was aimed to investigate the prevalence of obesity and its covariates including age among adult Khatri males and females. A total of 805 subjects (male = 381, female = 424) between age of 18 yr to 71 + yr residing in Shahjahanpur city, Uttar Pradesh, India were studied cross sectionally. The study highlights the trend of obesity in the population and also discusses in detail, the factors that cause it. An inverse relationship was obtained between level of physical activity and different relative weight categories based on body mass index in both the sexes. Similar association was observed in case of television watching time and overweight/obesity. With increase in hours of television watching the prevalence of overweight/obese also increased among both Khatri males and females.     

Histological study of pancreatic beta-cell loss in relation to the insulitis process in the non-obese diabetic mouse

Non-obese diabetic (NOD) mice spontaneously develop an autoimmune diabetes with higher incidence in females than in males. In order to elucidate possible factors involved in the different incidence of diabetes between male and female mice, we studied the progression of pancreatic beta-cell loss in relation to mononuclear cell infiltration of the pancreas (insulitis). We examined the pancreas of 76 NOD mice (39 males and 37 females) of different ages. The beta-cell content was assessed by immunoperoxidase staining of sections with an anti-insulin serum and the severity of insulitis was determined by haematoxylin staining of the same sections. A semi-quantitative criterion was used to grade both parameters. The results showed that females have a faster loss of beta-cell mass, which progressively decreases with the increase of severity of insulitis. In males, a medium to severe degree of insulitis is required before initial loss of beta cells occurs. Under the age of 10 weeks there was a significantly lower content of beta cells in females than males (2.84±0.03 vs 2.67±0.07; P=0.02). Since we never observed a significant difference in the degree of mononuclear cell infiltration in age-matched males and females, these data support the hypothesis of weaker beta-cell resistance to immunological attack in female mice. Thus beta-cell sensitivity, in addition to immunological activity, is an important factor in the pathogenesis of insulin dependent diabetes.     

Serum vitamins E, A and lipid peroxidation levels in Kurichias, an Indian tribal population.

Serum vitamins E, A, lipid peroxides, prevalence of dislipidemia, hypertension, obesity and smoking habits were assessed in a volunteer sample of 310 (175 males + 135 females) Kurichias, a tribal population of Kerala, India, who are enjoying longevity relatively free from age associated chronic problems. The mean serum levels of vitamins E and A were higher and lipid peroxides were lower with comparable ages of Indian and Western studies. The prevalence (age standardized to the world population of Segi 95% CI) was obesity 2.87 (1.22-4.53), central obesity 3.71 (2.27-5.15), hypertension 2.70 (1.92-3.48), hypercholesterolemia 0.71 (0.66-0.76), hypertriglyceridemia 2.60 (1.18-4.02) and low high density lipoprotein cholesterol 1.24 (1.07-1.42). Significant negative correlation was observed between vitamins and lipid peroxides. Serum cholesterol and triglycerides showed significant positive correlation with antioxidant vitamins and lipid peroxides. Blood pressure found positive correlation with lipid peroxides and no correlation with vitamins except systolic blood pressure having negative relation with vitamin A. Age showed negative correlation with vitamins and positive correlation with lipid peroxides, whereas lipid peroxides showed positive correlation with obesity only. In multivariate regression analysis serum cholesterol and old age groups were significant predictors of serum antioxidant vitamins and lipid peroxides. The higher levels of antioxidant vitamins, lower levels of lipid peroxides as well as low prevalence of CHD risk factors in Kurichias when compared to other populations suggest that antioxidants or increased intake of foods rich in antioxidants play a key role in their health and longevity.     

A novel model mouse for type 2 diabetes mellitus with early onset and persistent hyperglycemia

Various mouse models of type 2 diabetes have been established, but few of these show early onset and persistent hyperglycemia. We have established a congenic mouse strain (NSY.B6-Tyr⁺,A^y) in which a spontaneous mutation of the agouti yellow (A^y) gene, which causes obesity by hyperphagia, was introduced into the NSY strain, which shows increased glucose intolerance with age. This strain has been maintained as a segregating inbred strain by mating obese yellow (A^y/a) males with normal black (a/a) females. All yellow males showed marked obesity and hyperglycemia (mean blood glucose level >400 mg/dl) from 10 to 24 weeks of age. The yellow males also showed glucose intolerance and insulin resistance. They provide a potentially valuable model mouse for research into type 2 diabetes, hyperlipidemia, fatty liver, and renal glomerular complications. Yellow female mice also showed marked obesity, but the incidence of diabetes and the severity of various pathological conditions were milder than in yellow males. None of the black mice showed hyperglycemia in either sex. NSY.B6-Tyr⁺,A^y strain has good fertility and does not display inter-male aggression, making them useful as a new model for type 2 diabetes with early onset and persistent hyperglycemia.     

Different Impacts of Neck Circumference and Visceral Obesity on the Severity of Obstructive Sleep Apnea Syndrome

Our aim was to investigate the significance of neck circumference (NC) on the presence and severity of obstructive sleep apnea (OSA) syndrome independent of visceral fat (VF) obesity. A total of 219 subjects with suspected OSA underwent a complete polysomnography (PSG) study, along with the measurement of NC, and total body fat (TF) and VF levels (VFLs) measured by bioelectrical impedance analysis. We proposed NC divided by height (NC/H) as the simple index for height‐corrected NC in Japanese subjects. NC/H exhibited a significantly stronger correlation than NC per se with BMI (r = 0.781 vs. 0.675, P = 0.0178), TF (r = 0.531 vs. 0.156, P < 0.0001), and VF (r = 0.819 vs. 0.731, P = 0.0203), indicating that NC/H is a better indicator of visceral obesity than NC per se. Interestingly, despite the strong correlation between NC/H and VFL, VFL was significantly associated with the apnea‐hypopnea index (AHI) ≥5, ≥15, and ≥30, but not with ≥40 or ≥50, whereas NC/H was significantly associated with higher AHI values, i.e., AHI ≥50 but not with lower AHI value. Furthermore, multiple regression analyses revealed that VFL and NC/H were independently associated with the square root of AHI (AHI^0.5) levels in obese and nonobese patients, respectively. In conclusion, NC is associated with the severity of OSA independently of visceral obesity, especially in nonobese patients.     

Left ventricular hypertrophy in obese hypertensives: is it really eccentric? (An echocardiographic study)

In order to study left ventricular hypertrophy patterns in obese hypertensives, we examined 132 patients with essential hypertension by 2D, M-mode and Doppler echocardiography. The patients were classified in four comparable groups, corresponding to the values of Quetelet's body mass index (BMI) and grades of obesity. More obese hypertensives had on average larger left ventricles with thicker walls and larger left atria than less obese, or lean ones. Left ventricular mass increased significantly and progressively with advancing grades of obesity, but relative wall thickness (wall thickness/cavity size ratio) did not diminish. Doppler echocardiography revealed significantly higher prevalence of left ventricular diastolic dysfunction among obese than among lean hypertensives. In the second part of our study, we analyzed the subgroups defined by the severity of hypertension and the age of the patients. The correlation of the indices of left ventricular and left atrial hypertrophy with the BMI values was considerably better in the group of moderate than in the group of mild hypertension. The r values were 0.62 vs. 0.22 for left ventricular mass and 0.64 vs. 0.26 for left atrial dimension. The group of patients with severe hypertension was characterized by left ventricular cavity enlargement in correlation with increasing BMI values, but without corresponding left ventricular wall thickening. So called left ventricular "eccentricity index", as the reverse value of relative wall thickness, correlated well (r = 0.76) with the BMI values. The indices of left ventricular hypertrophy correlated with the BMI values slightly better in middle age groups than in the groups of the youngest (< or = 30 years) or the eldest (> or = 61 years) hypertensives. In conclusion, eccentric left ventricular hypertrophy does not seem to be a distinctive feature of hypertensive heart disease in obesity. There is only some tendency toward the "eccentricity" of left ventricular geometry which becomes more apparent in more severe forms of hypertension, especially in very obese persons.