Metabolic origin of insulin resistance in obesity with and without type 2 (non-insulin-dependent) diabetes mellitus.

A metabolic hypothesis is presented for insulin resistance in obesity, in the presence or absence of Type 2 (non-insulin-dependent) diabetes mellitus. It is based on physiological mechanisms including a series of negative feed-back mechanisms, with the inhibition of the function of the glycogen cycle in skeletal muscle as a consequence of decreased glucose utilization resulting from increased lipid oxidation in the obese. It considers the inhibition of glycogen synthase activity together with inhibition of glucose storage and impaired glucose tolerance. The prolonged duration of increased lipid oxidation, considered as the initial cause, may lead to Type 2 diabetes. This hypothesis is compatible with others based on the inhibition of insulin receptor kinase and of glucose transporter activities.

Obesity and smoking: can we catch two birds with one tax?

The debate on tobacco and fat taxes often treats smoking and eating as independent behaviors. However, the available evidence shows that they are interdependent, which implies that policies against smoking or obesity may have larger scope than expected. To address this issue, we propose a dynamic rational model where eating and smoking are simultaneous choices that jointly affect body weight and addiction to smoking. Focusing on direct and cross-price effects, we compare tobacco taxes and food taxes and we show that a single policy tool can reduce both smoking and body weight. In particular, food taxes can be more effective than tobacco taxes at simultaneously fighting obesity and smoking.

Relationship between cigarette smoking and abdominal obesity

Background: Although smokers tend to have a lower body-mass index (BMI) than non-smokers, smoking may affect body fat (BF) distribution. Some studies have assessed the association between smoking, BMI and waist circumference (WC), but, to our knowledge, no population-based studies assessed the relation between smoking and BF composition. We assessed the association between amount of cigarette smoking, BMI, WC and BF composition. Method: Data was analysed from a cross-sectional population-based study including 6'187 Caucasians aged 32-76 and living in Switzerland. Height, weight and WC were measured. BF, expressed in percent of total body weight, was measured by electrical bioimpedance. Abdominal obesity was defined as a WC 0102 cm for men and 088 cm for women and normal WC as <94 cm for men and <80 cm for women. In men, excess BF was defined as %BF 028.1, 28.7, 30.6 and 32.6 for age groups 32-44, 45-54, 55-64 and 65-76, respectively; the corresponding values for women were 35.9, 36.5, 40.5 and 44.4. Cigarette smoking was assessed using a self-reported questionnaire. Results: 29.3% of men and 25.0% of women were smokers. Prevalence of obesity, abdominal obesity, and excess of BF was 16.9% and 26.6% and 14.2% in men and 15.0%, 33.0% and 27.5% in women, respectively. Smokers had lower age-adjusted mean WC and percent of BF compared to non-smokers. However, among smokers, mean age-adjusted WC and BF increased with the number of cigarettes smoked per day: among light (1-10 cig/day), moderate (11-20) and heavy smokers (>20), mean ± SE %BF was 22.4 ± 0.3, 23.1 ± 0.3 and 23.5 ± 0.4 for men, and 31.9 ± 0.3, 32.6 ± 0.3 and 32.9 ± 0.4 for women, respectively. Mean WC was 92.9 ± 0.6, 94.0 ± 0.5 and 96.0 ± 0.6 cm for men, and 80.2 ± 0.5, 81.3 ± 0.5 and 83.3 ± 0.7 for women, respectively. Compared with light smokers, the age-adjusted odds ratio (95% Confidence Interval) for excess of BF was 1.04 (0.58 to 1.85) for moderate smokers and 1.06 (0.57 to 1.99) for heavy smokers in men (p-trend = 0.9), and 1.35 (0.92 to 1.99) and 2.26 (1.38 to 3.72), respectively, in women (p-trend = 0.04). Odds ratio for abdominal obesity vs. normal WC was 1.32 (0.81 to 2.15) for moderate smokers and 1.95 (1.16 to 3.27) for heavy smokers in men (p-trend <0.01), and 1.15 (0.79 to 1.69) and 2.36 (1.41 to 3.93) in women (p-trend = 0.03). Conclusion: WC and BF were positively and dose-dependently associated with the number of cigarettes smoked per day in women, whereas only WC was dose dependently and significantly associated with the amount of cigarettes smoked per day in men. This suggests that heavy smokers, especially women, are more likely to have an excess of BF and to accumulate BF in the abdomen compared to lighter smokers.

The different types of internal hernia after laparoscopic Roux-En-Y gastric by-bass for morbid obesity : MDCT features : P5

Purpose: 1. To provide an overview of the different types of internal hernia (IH) occurring after laparoscopic Roux-en-Y gastric bypass (LRYGBP) performed for morbid obesity. 2. To describe the correspondent MDCT features in relation with the underlying anatomical landmarks in order to differentiate their localisation and to direct the surgeon during following laparoscopic closure of mesenteric defects. Methods and materials: LRYGBP performed for morbid obesity is associated with less perioperative complications, shorter hospital stay and a more rapid recovery compared with the open surgical procedure. However, a relatively high incidence of IH is seen that may be due to the laparoscopic approach, but also caused by rapid weight loss with consecutive loosening of the mesenteric sutures. Results: After briefly reviewing the surgical procedure of LRYGBP (ante- versus retrocolic) we describe the exact anatomical landmarks of the different types of IH occurring at any time after operation: They are caused by surgical defects either at the level of the transverse colon mesentery, at the Petersen's space, which represents an opening between the mesocolon and jejunal mesentery, or at the enteroenterostomy site. Typical MDCT features of each IH type in axial and coronal plane as well as targeted vascular reconstructions are demonstrated. Conclusion: Exact knowledge about underlying pathophysiology and anatomical landmarks is essential for distinguishing the different types of IH occurring after LRYGBP on MDCT, since radiological features are difficult to recognize and may even overlap. The radiologist should be aware of the potential anatomic sites to ensure subsequent straightforward laparoscopic exploration.

Carbohydrate metabolism and de novo lipogenesis in human obesity.

Respiratory exchange was measured during 14 consecutive hours in six lean and six obese individuals after ingestion of 500 g of dextrin maltose to investigate and compare their capacity for net de novo lipogenesis. After ingestion of the carbohydrate load, metabolic rates rose similarly in both groups but fell earlier and more rapidly in the obese. RQs also rose rapidly and remained in the range of 0.95 to 1.00 for approximately 8 h in both groups. During this time, RQ exceeded 1.00 for only short periods of time with the result that 4 +/- 1 g and 5 +/- 3 g (NS) of fat were synthesized via de novo lipogenesis in excess of concomitant fat oxidation in the lean and obese subjects, respectively. Results demonstrate that net de novo lipid synthesis from an unusually large carbohydrate load is not greater in obese than in lean individuals.

Transmission and diagnosis of equine babesiosis in South Africa

The transmission and prevalence of Babesia equi and B. caballi are being studied. Rhipicephalus evertsi mimeticus an ixodid tick from Namibia was identified as a new vector of B. equi, however, R. turanicus, previously reported to be a vector, failed to transmit both B. equi and B. caballi in the laboratory. The accurate diagnosis of B. caballi is being investigated because the nature of its low level parasitaemia does not allow easy detection in thin blood smears, routinely used for diagnosis, by clinicians. Consequently its role as a pathogen remains obscure. The importance of identifying infected horses, destined for export to Babesia-free coutries, is also stressed. Thock and thin blood smears, serology (IFAT) and DNA probes are currently employed to study disease prevalence. To date 293 healthy, adult, throughbred horses have been screened by all three methods. The percentage positives are as follows: B. equi 4.4%, 70.6%, 13% and B. caballi 0.7%, 37%, 18.4% respectively. The DNA probes were more sensitive than blood smear examination for diagnosing carrier infections but are probably not sensitive enough to identify all carrier infections. A poor correlation was found between detection of the parasites' DNA and seropositivity. However, polymerase chain reaction could be used to amplify parasite DNA in a particular sample and its could result in more accurate diagnosis.

Dose-dependent positive association between cigarette smoking, abdominal obesity and body fat: cross-sectional data from a population-based survey.

ABSTRACT: BACKGROUND: Although smokers tend to have a lower body-mass index than non-smokers, smoking may favour abdominal body fat accumulation. To our knowledge, no population-based studies have assessed the relationship between smoking and body fat composition. We assessed the association between cigarette smoking and waist circumference, body fat, and body-mass index. METHODS: Height, weight, and waist circumference were measured among 6,123 Caucasians (ages 35-75) from a cross-sectional population-based study in Switzerland. Abdominal obesity was defined as waist circumference>=102 cm for men and >=88 cm for women. Body fat (percent total body weight) was measured by electrical bioimpedance. Age- and sex-specific body fat cut-offs were used to define excess body fat. Cigarettes smoked per day were assessed by self-administered questionnaire. Age-adjusted means and odds ratios were calculated using linear and logistic regression. RESULTS: Current smokers (29% of men and 24% of women) had lower mean waist circumference, body fat percentage, and body-mass index compared with non-smokers. Age-adjusted mean waist circumference and body fat increased with cigarettes smoked per day among smokers. The association between cigarettes smoked per day and body-mass index was non-significant. Compared with light smokers, the adjusted odds ratio (OR) for abdominal obesity in men was 1.28 (0.78-2.10) for moderate smokers and 1.94 (1.15-3.27) for heavy smokers (P=0.03 for trend), and 1.07 (0.72-1.58) and 2.15 (1.26-3.64) in female moderate and heavy smokers, respectively (P<0.01 for trend). Compared with light smokers, the OR for excess body fat in men was 1.05 (95% CI: 0.58-1.92) for moderate smokers and 1.15 (0.60-2.20) for heavy smokers (P=0.75 for trend) and 1.34 (0.89-2.00) and 2.11 (1.25-3.57), respectively in women (P=0.07 for trend). CONCLUSION: Among smokers, cigarettes smoked per day were positively associated with central fat accumulation, particularly in women.

PGC1alpha expression is controlled in skeletal muscles by PPARbeta, whose ablation results in fiber-type switching, obesity, and type 2 diabetes.

Mice in which peroxisome proliferator-activated receptor beta (PPARbeta) is selectively ablated in skeletal muscle myocytes were generated to elucidate the role played by PPARbeta signaling in these myocytes. These somatic mutant mice exhibited a muscle fiber-type switching toward lower oxidative capacity that preceded the development of obesity and diabetes, thus demonstrating that PPARbeta is instrumental in myocytes to the maintenance of oxidative fibers and that fiber-type switching is likely to be the cause and not the consequence of these metabolic disorders. We also show that PPARbeta stimulates in myocytes the expression of PGC1alpha, a coactivator of various transcription factors, known to play an important role in slow muscle fiber formation. Moreover, as the PGC1alpha promoter contains a PPAR response element, the effect of PPARbeta on the formation and/or maintenance of slow muscle fibers can be ascribed, at least in part, to a stimulation of PGC1alpha expression at the transcriptional level.

Failure of dietary fat intake to promote fat oxidation: a factor favoring the development of obesity.

Seven young men spent three nights and 2 d in a respiration chamber where their rates of energy expenditure and substrate oxidation were continuously measured by indirect calorimetry. During the first 24 h they ingested a mixed maintenance diet containing 35% of calories as fat. An additional amount of 106 +/- 6 g fat/24 h (means +/- SD) was added to this diet during the following 36 h. The fat supplement (987 +/- 55 kcal/d) did not alter 24-h energy expenditure (2783 +/- 232 vs 2820 +/- 284 kcal/d) and failed to promote the use of fat as a metabolic fuel (fat oxidation 1032 +/- 205 vs 1042 +/- 205 kcal/d). The overall energy balance was closely correlated with the fat balance (r = 0.96, p less than 0.001) but not with the carbohydrate balance (r = -0.12, NS). These data indicate that substantial imbalances between intake and oxidation are much more likely for fat than for carbohydrate.

The different types of internal hernia after laparoscopic Roux-En-Y gastric by-pass for morbid obesity: MDCT features [C-419]

Learning Objectives: 1. To provide an overview of the different types of internal hernia (IH) occurring after laparoscopic Roux‑en‑Y gastric bypass (LRYGBP) for morbid obesity. 2. To describe correspondent MDCT features in relation with the underlying anatomical landmarks in order to differentiate their localisation and to direct the surgeon during following laparoscopic closure of mesenteric defects. Background: LRYGBP for morbid obesity is associated with less perioperative complications, shorter hospital stay and a more rapid recovery compared with the open surgical procedure. However, a relatively high incidence of IH is seen that may be due to the laparoscopic approach, but also caused by rapid weight loss with consecutive loosening of the mesenteric sutures. Procedure Details: After briefly reviewing the surgical procedure of LRYGBP (ante‑ versus retrocolic), we describe the exact anatomical landmarks of the different types of IH occurring at any time after operation: They are caused by surgical defects at the level of the transverse colon mesentery, at the Petersen's space, which represents an opening between the mesocolon and jejunal mesentery, or at the entero‑enterostomy site. Typical MDCT features of each IH type in axial and coronal planes as well as targeted vascular reconstructions are demonstrated. Conclusion: Exact knowledge about underlying pathophysiology and anatomical landmarks is essential for distinguishing the different types of IH occurring after LRYGBP on MDCT, since radiological features are difficult to recognize and may even overlap. The radiologist should be aware of the potential anatomic sites to ensure subsequent straightforward laparoscopic exploration.