Pharmacological and surgical treatments for obesity

Bariatric Surgery and Liver Disease: General Considerations and Role of the Gut-Liver Axis

Weight loss is a therapeutic solution for many metabolic disorders, such as obesity and its complications. Bariatric surgery aims to achieve lasting weight loss in all patients who have failed after multiple dietary attempts. Among its many benefits, it has been associated with the regression of non-alcoholic fatty liver disease (NAFLD), which is often associated with obesity, with evidence of substantial improvement in tissue inflammation and fibrosis. These benefits are mediated not only by weight loss, but also by favorable changes in systemic inflammation and in the composition of the gut microbiota. Changes in microbial metabolites such as short-chain fatty acids (SCFAs), capable of acting as endocrine mediators, and bile acids (BAs) as well as modifications of the gut-brain axis, are among the involved mechanisms. However, not all bariatric surgeries show beneficial effects on the liver; those leading to malabsorption can cause liver failure or a marked worsening of fibrosis and the development of cirrhosis. Nevertheless, there are still many unclear aspects, including the extent of the benefits and the magnitude of the risks of bariatric surgery in cirrhotic patients. In addition, the usefulness and the safety of these procedures in patients who are candidates to or who have undergone liver transplant need solid supporting evidence. This paper aims to review literature data on the use of bariatric surgery in the setting of chronic liver disease.

Perspective on biomaterials used in the surgical treatment of morbid obesity

Morbid obesity is defined as having a body mass index greater than or equal to 40.0 kg m(-2), or 37.0 kg m(-2) with comorbidities. Bariatric surgery remains the most effective treatment for morbid obesity. Bariatric procedures such as sleeve gastrectomy, vertical banded gastroplasty and adjustable gastric banding all generate excess body-weight loss typically over 3-5 years. The biomaterials used during these procedures, namely silicone, polypropylene, expanded polytetrafluoroethylene and titanium, are all non-degradable biomaterials. Hence, their presence in vivo exceeds the functional requirement of an implant to treat morbid obesity. Accordingly, research into non-invasive and reversible surgical procedures has increased, particularly in light of the dramatic increase in paediatric obesity. Tissue engineering is an alternative approach to treat morbid obesity, as it incorporates both engineering and biological principles into the design and development of an implant to surgically treat morbid obesity. It is hypothesized that a biodegradable polymer to treat morbid obesity could be developed to effectively promote excess weight loss. The aim of this review is to discuss morbid obesity with regards to its aetiology, prevalence and current modalities of treatment. Specifically, the shortcomings of the biomaterials currently used to surgically treat morbid obesity shall be reviewed, and alternative biomaterials shall be proposed.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

Nutritional consequences of weight-loss surgery

Nutritional deficiencies are already present in many morbidly obese patients before weight-loss surgery. Appropriate preoperative detection and correction is essential. The severity and pattern of deficiencies is dependent on the presence of preoperative uncorrected deficiency, the type of procedure performed varying with the degree of restriction or the length of bypassed small intestine, the modification of eating behavior, the development of complications, compliance with oral multivitamin and mineral supplementation, and compliance with follow-up. Rigorous control of fluids and electrolytes with establishment of adequate oral nutrition is important in the immediate postoperative period. Regular follow-up of the metabolic and nutritional status of the patient is essential, with life-long multivitamin and mineral supplementation.

The Obesity Epidemic: Current and Future Pharmacological Treatments

The unabated rise in the prevalence of obesity is a challenge for global health care systems. Efforts to reverse this trend by dietary or behavioral counseling have not been successful, which has stimulated efforts to find a role for pharmacotherapy. Currently only a small number of antiobesity drugs are approved for long-term use and only a few compounds are in clinical development. Despite recent progress in the understanding of the regulation of energy balance, drug discovery has been less productive than expected. In the present review, the clinically available antiobesity agents are discussed. Examples of drug candidates that are currently in development are given and the possible future range of antiobesity agents is illustrated by the targets being addressed in drug discovery. Finally, the efficacy of antiobesity agents and their value in the treatment of obesity are assessed in comparison with other therapeutic approaches, such as surgery and changes in lifestyle.

Treatment of obesity

For primary care physicians, obesity is one of the most challenging problems confronted in office practice. The disorder is Increasing in prevalence despite the efforts of both patients and physicians. Treatment requires a multimodality approach that addresses diet, physical activity, and behavioral issues. Medication and surgical approaches may be appropriate as well. This review outlines the evidence for each approach, suggests how primary care physicians can best help obese patients, and provides practical tips for weight loss.

The dilemma of the metabolic syndrome in children and adolescents: disease or distraction?

BACKGROUND

The alarming increase of obesity in children occurring globally is raising concern about the implications for development, at earlier ages, of atherosclerosis and cardiovascular disease and is driving efforts to evaluate and predict risk in the young. A major component of this undertaking has been directed to adapting for children the criteria described in adults as the metabolic syndrome (MS).

METHODS

This article briefly examines the status of and controversy about definition of the MS in adults and its value, and then it moves on to review the descriptions of the MS in the pediatric age group. This is done primarily from the point of view of its usefulness to the clinician. The ranges of the criteria used by different investigators, the differences in their prevalence and their effectiveness in predicting cardiovascular risk are discussed. Current information about cardiovascular risk factors in children, their progression into adulthood and their correlation with atherosclerosis in children and young adults is outlined. Finally, the current information and recommendations for treatment, in children, of cardiovascular risk factors including those composing the MS are reviewed.

CONCLUSIONS

One conclusion is that there needs to be consensus about the criteria for defining the MS in children if its use as a diagnosis is to be helpful in this age group. A second conclusion questions the value of using this syndromic collection of risk factors in children rather than concentrating on the risk factors themselves, evaluating their importance in early cardiovascular risk and assessing the safety and efficacy of intervention in early life.

Physiologic, psychologic, and metabolic consequences of bariatric surgery

The successful management of obesity is essential to treat effectively its associated comorbidities such as systemic hypertension, diabetes, dyslipidemias, and obstructive sleep apnea. Current weight loss recommendations include reduced caloric intake, exercise, and pharmacologic treatments that often result in a minimal weight loss that is rarely maintained. Conversely, surgical procedures such as Roux-en-Y gastric bypass, adjustable gastric banding, vertical banded gastroplasty, or biliopancreatic diversion result in a more successful and maintained long-term weight loss. Bariatric surgery-induced weight loss is associated with improvements in cardiovascular risk factors such as systemic hypertension, hypertriglyceridemia, and low levels of high-density lipoprotein cholesterol. However, hypercholesterolemia does not appear to benefit from surgically induced weight loss. Patients also note improvement in associated respiratory comorbidities such as asthma and obstructive sleep apnea as well as diabetes. Although the risks of bariatric surgery are numerous, including gastrointestinal and respiratory complications and associated nutritional deficiencies, in an appropriately selected surgical candidate, as detailed by National Institutes of Health guidelines, the surgical treatment of obesity warrants serious consideration.