Obesity and hypertension: two epidemics or one?

The association between obesity and hypertension is well documented, although the exact nature of this relation remains unclear. Sympathetic nervous and renin-angiotensin-aldosterone system activation appear to play an important role in the sodium and water retention, rightward shift in the pressure-natriuresis, and blood pressure elevation observed in obese individuals. Visceral obesity and the ectopic deposition of adipose tissue may be important in the activation of these systems and in the target organ damage that ensues. Weight loss is critical in the effective management of obesity hypertension and the accompanying target organ damage, although recidivism rates are high. However, prevention of weight gain should be the major priority for combating hypertension and its consequences in the future. The present review will provide an overview of our understanding of the etiology, pathophysiology, and treatment of obesity hypertension. Our focus is on the state of knowledge in humans. The potential role of abdominal obesity is considered throughout our review. We refer to relevant animal literature for supportive evidence and where little or no data in humans are available.     

Breastfeeding and Childhood Obesity: Shift of the Entire BMI Distribution or Only the Upper Parts?

A protective effect of breastfeeding on overweight (binary) has been reported by meta-analyses using logistic regression, whereas studies using linear regression and BMI (continuous) detected no significant association. To assess the relationship of these differences with different outcome classification, we compared results for linear, logistic, and quantile regression models in a cross-sectional data set of considerable size. Height, weight, and questionnaire data on 9,368 preschool children were collected during school-entry examinations in 1999 and 2002 in Bavaria, Southern Germany. We calculated multivariable linear, logistic, and quantile regression models with outcomes BMI, overweight, obesity, and BMI quantiles (as appropriate). Models considered the covariates breastfeeding (breastfed vs. never breastfed), gender, age, smoking in pregnancy, TV watching, maternal BMI, parental education, and early infant weight gain. No significant association was found in the linear regression model. In the logistic model, a significant association was observed for obesity (odds ratio: 0.72 (95% confidence interval (CI) 0.55, 0.94)). In quantile regression no significant point estimates were observed for the percentiles of 0.4-0.8. However, breastfeeding reduced the BMI of children having values on the 90th and 97th percentiles by -0.23 (95% CI -0.39, -0.07) and -0.26 (95% CI -0.45, -0.07) kg/m(2), respectively, on average. In contrast, breastfeeding was significantly associated with a low shift toward higher BMI values for BMI quantiles of 0.03 and from 0.1 to 0.3. The detection of associations between breastfeeding and childhood body composition might be related to the coding of the response variable (continuous or binary) and the statistical method used (linear, logistic, or quantile regression). Quantile regression should additionally be applied in such studies.     

Obesity and post-prandial lipid metabolism. Feast or famine?

Both in Western countries and in third world countries there is an increasing incidence of obesity. Obesity per se or insulin resistance associated with obesity may increase cardiovascular risk factors including dyslipidemia, hypertension and Type 2 diabetes. Over the past decade the understanding has increased of specific mediators in the hypothalamus that are involved in regulating food intake and body weight. In obese humans fasting plasma lipids can be normal but postprandial lipid metabolism is abnormal with an accumulation of triglyceride-rich remnant lipoproteins. In viscerally obese men chylomicron remnant catabolism was markedly decreased when compared with lean individuals. The decreased clearance of chylomicron remnants in viscerally obese subjects may be explained by competition between chylomicron remnants and the increased hepatic production of VLDL for clearance by low density lipoprotein receptors. Increased food intake in rodent models of obesity was shown to be associated with a delay in the catabolism of remnant lipoprotein particles. Prevention of hyperphagia was found to correct the impairment in the metabolism of remnant lipoproteins. Under fasting and food restricted conditions the improvement of remnant metabolism was associated with an increased oxidation of remnant lipids as determined by a novel stable isotope breath test. Anti-obesity and lipid lowering drugs have been used for the treatment of obesity. Inhibitors of cholesterol synthesis inhibitors (statins) have been shown to be effective in treating dyslipidemia. Inhibition of cholesterol synthesis with Atorvastatin was shown to improve chylomicron metabolism by increasing chylomicron remnant catabolism in obese subjects as assessed by the newly developed stable isotope breath test.     

Exosomes and retroviruses: the chicken or the egg?

Retroviruses appropriate pre‐existing cellular machineries to propagate. In the last decade, impressive similarities have been observed in the generation and dissemination in the host cells of retroviruses and small cellular vesicles known as exosomes. These cellular vesicles are thought to facilitate intercellular communication processes and mediate immune functions. However, their link to the retroviral life cycle has given rise to distinct hypotheses and puzzling dilemmas. Are exosomes the antecessors of retroviruses or do retroviruses merely exploit the same cellular machinery designated for exosome biosynthesis? Here, we address these fascinating evolutionary questions by reviewing recent discoveries and analysing the controversies surrounding them.     

Will All Americans Become Overweight or Obese? Estimating the Progression and Cost of the US Obesity Epidemic

We projected future prevalence and BMI distribution based on national survey data (National Health and Nutrition Examination Study) collected between 1970s and 2004. Future obesity-related health-care costs for adults were estimated using projected prevalence, Census population projections, and published national estimates of per capita excess health-care costs of obesity/overweight. The objective was to illustrate potential burden of obesity prevalence and health-care costs of obesity and overweight in the United States that would occur if current trends continue. Overweight and obesity prevalence have increased steadily among all US population groups, but with notable differences between groups in annual increase rates. The increase (percentage points) in obesity and overweight in adults was faster than in children (0.77 vs. 0.46-0.49), and in women than in men (0.91 vs. 0.65). If these trends continue, by 2030, 86.3% adults will be overweight or obese; and 51.1%, obese. Black women (96.9%) and Mexican-American men (91.1%) would be the most affected. By 2048, all American adults would become overweight or obese, while black women will reach that state by 2034. In children, the prevalence of overweight (BMI >/= 95th percentile, 30%) will nearly double by 2030. Total health-care costs attributable to obesity/overweight would double every decade to 860.7-956.9 billion US dollars by 2030, accounting for 16-18% of total US health-care costs. We continue to move away from the Healthy People 2010 objectives. Timely, dramatic, and effective development and implementation of corrective programs/policies are needed to avoid the otherwise inevitable health and societal consequences implied by our projections .     

Obesity and the rate of time preference: is there a connection?

It is hypothesized that recent trends in US and worldwide obesity are, in part, related to an increase in the marginal rate of time preference, where time preference refers to the rate at which people are willing to trade current benefit for future benefit. The higher the rate of time preference, the larger is the factor by which individuals discount the future health risks associated with current consumption. Data from the United States, as well as international evidence, suggest that a relationship between these two variables is plausible. The authors encourage researchers to explore the possible link between obesity and time preference, as important insights are likely to result.     

Anonymous fecal sampling and NIRS studies of diet quality: Problem or opportunity?

Investigating the drivers of diet quality is a key issue in wildlife ecology and conservation. Fecal near infrared reflectance spectroscopy (f‐NIRS) is widely used to assess dietary quality since it allows for noninvasive, rapid, and low‐cost analysis of nutrients. Samples for f‐NIRS can be collected and analyzed with or without knowledge of animal identities. While anonymous sampling allows to reduce the costs of individual identification, as it neither requires physical captures nor DNA genotyping, it neglects the potential effects of individual variation. As a consequence, regression models fitted to investigate the drivers of dietary quality may suffer severe issues of pseudoreplication. I investigated the relationship between crude protein and ecological predictors at different time periods to assess the level of individual heterogeneity in diet quality of 22 marked chamois Rupicapra rupicapra monitored over 2 years. Models with and without individual grouping effect were fitted to simulate identifiable and anonymous fecal sampling, and model estimates were compared to evaluate the consequences of anonymizing data collection and analysis. The variance explained by the individual random effect and the value of diet repeatability varied with seasons and peaked in winter. Despite the occurrence of individual variation in dietary quality, ecological parameter estimates under identifiable or anonymous sampling were consistently similar. This study suggests that anonymous fecal sampling may provide robust estimates of the relationship between dietary quality and ecological correlates. However, since the level of individual heterogeneity in dietary quality may vary with species‐ or study‐specific features, inconsequential pseudoreplication should not be assumed in other taxa. When individual differences are known to be inconsequential, anonymous sampling allows to optimize the trade‐off between sampling intensity and representativeness. When pseudoreplication is consequential, however, no conclusive remedy exists to effectively resolve nonindependence.     

Panic attacks and supraventricular tachycardias: the chicken or the egg?

Panic attacks occur in about 2 % of the population. Symptoms include a racing or pounding heart beat, chest pain, dizziness, light-headedness, nausea, difficulty in breathing, tingling or numbness in the hands, flushes or chills, dreamlike sensations or perceptual distortions. The symptoms of paroxysmal supraventricular tachycardia (PSVT) may be similar. A PSVT is often difficult to document on the ECG since it has often ceased before the patient comes to medical attention. Besides, a tachycardia may still be present and even be documented but interpreted as a phenomenon secondary to the panic attack. In addition, ECG abnormalities between episodes can often not be identified. The evidence that in some patients paroxysmal SVT is the cause, but not the consequence of a panic attack, is based on observations that catheter ablation was able to cure patients presenting with panic disorders. To better establish the prevalence of SVT as the underlying mechanism of a panic attack, there is a need for prospective studies and/or registries. Whereas gastric ulcer has in some patients changed from a psychosomatic disorder to an infectious disease, we may hypothesise that a certain proportion of panic disorders may mutate into an underlying arrhythmia rather than a primary psychiatric disorder.     

Restoration and Economics: A Union Waiting to Happen?

In this article, our objective is to introduce economics as a tool for the planning, prioritization, and evaluation of restoration projects. Studies that develop economic estimates of public values for ecological restoration employ methods that may be unfamiliar to practitioners. We hope to address this knowledge gap by describing economic concepts in the context of ecological restoration. We have summarized the most common methods for estimating the costs and benefits of restoration projects as well as frameworks for decision analysis and prioritization. These methods are illustrated in a review of the literature as it applies to terrestrial restoration in the United States, with examples of applications of methods to projects. Our hope is that practitioners will consider collaborating with economists to help ensure that restoration costs and benefits are identified and understood.     

Obesity and the gut microbiota: does up-regulating colonic fermentation protect against obesity and metabolic disease?

Obesity is now considered a major public health concern globally as it predisposes to a number of chronic human diseases. Most developed countries have experienced a dramatic and significant rise in obesity since the 1980s, with obesity apparently accompanying, hand in hand, the adoption of "Western"-style diets and low-energy expenditure lifestyles around the world. Recent studies report an aberrant gut microbiota in obese subjects and that gut microbial metabolic activities, especially carbohydrate fermentation and bile acid metabolism, can impact on a number of mammalian physiological functions linked to obesity. The aim of this review is to present the evidence for a characteristic "obese-type" gut microbiota and to discuss studies linking microbial metabolic activities with mammalian regulation of lipid and glucose metabolism, thermogenesis, satiety, and chronic systemic inflammation. We focus in particular on short-chain fatty acids (SCFA) produced upon fiber fermentation in the colon. Although SCFA are reported to be elevated in the feces of obese individuals, they are also, in contradiction, identified as key metabolic regulators of the physiological checks and controls mammals rely upon to regulate energy metabolism. Most studies suggest that the gut microbiota differs in composition between lean and obese individuals and that diet, especially the high-fat low-fiber Western-style diet, dramatically impacts on the gut microbiota. There is currently no consensus as to whether the gut microbiota plays a causative role in obesity or is modulated in response to the obese state itself or the diet in obesity. Further studies, especially on the regulatory role of SCFA in human energy homeostasis, are needed to clarify the physiological consequences of an "obese-style" microbiota and any putative dietary modulation of associated disease risk.     

Chlamydiales and the innate immune response: friend or foe?

Pathogenicity of Chlamydia and Chlamydia-related bacteria could be partially mediated by an enhanced activation of the innate immune response. The study of this host pathogen interaction has proved challenging due to the restricted in vitro growth of these strict intracellular bacteria and the lack of genetic tools to manipulate their genomes. Despite these difficulties, the interactions of Chlamydiales with the innate immune cells and their effectors have been studied thoroughly. This review aims to point out the role of pattern recognition receptors and signal molecules (cytokines, reactive oxygen species) of the innate immune response in the pathogenesis of chlamydial infection. Besides inducing clearance of the bacteria, some of these effectors may be used by the Chlamydia to establish chronic infections or to spread. Thus, the induced innate immune response seems to be variable depending on the species and/or the serovar, making the pattern more complex. It remains crucial to determine the common players of the innate immune response in order to help define new treatment strategies and to develop effective vaccines. The excellent growth in phagocytic cells of some Chlamydia-related organisms such as Waddlia chondrophila supports their use as model organisms to study conserved features important for interactions between the innate immunity and Chlamydia.     

Native or Exotic? Double or Single? Evaluating Plants for Pollinator-friendly Gardens

In a series of dawn-to-dusk studies, we examined the natureand accessibility of nectar rewards for pollinating insectsby monitoring insect visits and the secretion rate and standingcrop of nectar in the British native plant species Salvia pratensis,Stachys palustris, S. officinalis, Lythrum salicaria, Linariavulgaris, the non-native Calendula officinalis, Petunia x hybrida,Salvia splendens, and the possibly introduced Saponaria officinalis.We also compared single with double variants ofLotus corniculatus, Saponaria officinalis, Petunia x hybrida andCalendula officinalis. All the British species studied are nectar-rich and are recommendedfor pollinator-friendly gardens. They showed maximal secretionrates of about 10–90 µg sugar per flower h^-1, andmost had mean standing crops of about 5–60 µg sugarper flower. In all British species studied, the corolla wasdeep enough for the relatively long-tongued bumblebee Bombuspascuorum, but the shallower flowers of Lythrum salicaria werealso much visited by shorter-tongued bees and hoverflies, aswell as by butterflies. The exotic Salvia splendens, presumablycoevolved with hummingbirds in the Neotropics, has such deepflowers that British bees cannot reach the nectar except bycrawling down the corolla. With a secretion rate approaching300 µg sugar per flower h^-1and little depletion by insects,S. splendens accumulated high standing crops of nectar. S. splendens,and single and double flowers of the two probably moth-pollinatedspecies Petunia x hybrida and Saponaria officinalis, receivedfew daytime visits despite abundant nectar but Calendula waswell visited by hoverflies and bees. We compared single anddouble variants of Lotus corniculatus,Petunia x hybrida andCalendula officinalis, and also Saponaria officinalis, the lastbeing probably introduced in Britain (Stace, 1997 New floraof the British Isles. 2nd edn. Cambridge: Cambridge UniversityPress). In Petunia, Saponaria and Lotus, double flowers secretedlittle or no nectar. In Calendula, where doubling involved achange in the proportion of disc and ray florets rather thanmodification of individual flower structure, double and singlecapitula had similar standing crops of nectar. Except inCalendula, exotic or double flowers were little exploited by insect visitors.In the exotics, this was probably due to the absence or scarcityof coevolved pollinators, coupled, in double flowers, with theabsence of nectar. Copyright 2001 Annals of Botany Company Salvia pratensis, Salvia splendens, Stachys palustris, Stachys officinalis,Lythrum salicaria , Linaria vulgaris, Lotus corniculatus, Saponaria officinalis,Petunia x hybrida, Calendula officinalis, wild flowers, double flowers, gardens, nectar, secretion rate, standing crop, pollinators, bumblebees, Bombus, honeybees, Apis, hoverflies, butterflies,Anthidium manicatum     

Evaluating data from behavioral analysis: visual inspection or statistical models?

Traditional behavior analysis relies upon single-subject study designs and visual inspection of graphed data to evaluate the efficacy of experimental manipulations. Attempts to apply statistical inferential procedures to analyze data have been successfully opposed for many decades, despite problems with visual inspection and increasingly cogent arguments to utilize inferential statistics. In a series of experiments, we show that trained behavior analysts often identify level shifts in responding during intervention phases ('treatment effect') in modestly autocorrelated data, but trends are either misconstrued as level treatment effects or go completely unnoticed. Errors in trend detection illustrate the liabilities of using visual inspection as the sole means by which to analyze behavioral data. Meanwhile, because of greatly increased computer power and advanced mathematical techniques, previously undeveloped or underutilized statistical methods have become far more sophisticated and have been brought to bear on a variety of problems associated with repeated measures data. I present several nonparametric procedures and other statistical techniques to evaluate traditional behavioral data to augment, not replace, visual inspection procedures.     

Obesity and melanoma: could fat be fueling malignancy?

Over the last decade, it has become increasingly clear that adipose tissue, and particularly adipocytes, contributes to tumor progression. Obesity, an ever‐increasing worldwide phenomenon, exacerbates this effect. The influence of obesity on melanoma remains poorly studied, although recent data do underline an association between the two diseases in both humans and murine models. Herein, we review the impact of obesity on melanoma incidence and progression and discuss the underlying mechanisms known to be involved. Adipose tissue favors the proliferation and aggressiveness of melanoma cells through a direct dialog, mediated by soluble factors and by exosomes, and through remodeling of the tumor microenvironment. This knowledge could, in the future, help to design new personalized therapeutic options for obese melanoma patients.