Bariatric Surgery and Adjustable Gastric

Bariatric Surgery and Adjustable Gastric Banding

Obesity is certainly considered one of the most prevalent health problems in any of modern society. Despite an apparent reduction in calorie consumption, and an improved social comprehension of nutrition and exercise programs, the prevalence of obesity has been on the rise over the last several generations. This is understood to be primarily the result of an ever increasing sedentary lifestyle for children and adults. The condition of obesity has been closely scrutinized by both psychologists and physicians. For researchers, obesity can seem an enigmatical problem due to its complex and apparently diverse etiology. There is a need to create a verifiable animal model to assist in conducting more efficient and reproducible research in this area.

Despite extensive research, the underlying causes of obesity are not yet fully understood; what is clear is that obesity is caused by a persistent caloric intake that exceeds the energy output needs of the body. Many variables come into play when discussing the problem of obesity and its causes. These also include numerous psychological, social and cultural factors as well as a host of interrelated physiological factors which can include: genetic, anatomic, endocrine, biochemical as well neuro-regulatory factors (Cook, Rutishauser & Allsopp 2001; De-Looper & Bhatia 2001; Webber 1994).

It appears that, over the years, a lack of success in developing a profile of the psychological characteristics of the obese person has made it difficult to develop appropriate treatment strategies. A number of studies have found no differences between obese and normal-weight people on a variety of variables. (Halmi, Long, Stunkard & Mason 1980: 471)

However, the consequences are understood and well documented, particularly for the "morbidly" obese that are by definition more than twice their ideal body weight for height and sex or at least 100 lbs. overweight. (Lin, Smith, Fawkes, Robinson and Chaplin 2007). The most commonly reported complications and associated risks of obesity include: diabetes, hypertension, and increased risk of cardiovascular disease, musculoskeletal and metabolic difficulties, significant psychosocial distress and a strong possibility of early death. For practitioners, obesity may appear an intractable disorder as a multitude of treatments have proven ineffective for long-term weight loss. For the obese individual, obesity can seem an enslaving condition given the refractory nature of the disorder greater (Lin, Smith, Fawkes, Robinson and Chaplin 2007). Various treatment approaches have been utilized such as: nutritional guidance and diet planning, protein-sparing liquid diets and other forms of fasting, pharmacological interventions with amphetamine or other anorectic drugs and exercise programs. Psychotherapy and behaviour modification have produced mixed results (Parry 2006). Treatment regimens abound, yet it can generally be said that satisfactory interventions continue to prove elusive and many problems remain. In the case of extreme or morbid obesity, surgical interventions have been increasingly utilized over the past three decades and recent advances appear promising in terms of decreased mortality, improved quality of life and improved eating habits (Foley 1992). Long-term weight loss, measured in terms of percent overweight reduction, represents the most relevant value in determining the relative worth of any weight loss intervention. As we will see, the jury is still out regarding "the effectiveness of the gastric bypass, although the results certainly are much more promising than conventional weight loss methods." ("Biliary pancreatic diversion" 2009: 43)

There is a large body of literature on the condition of obesity, and a growing number of studies contrasting and comparing various treatments for morbid obesity such as gastric bypass surgical procedures. Few studies have reported on the use of psychological tests and interviews for screening patients to assess their suitability for gastric bypass surgery or to facilitate preoperative and postoperative treatment.

Clearly, obesity derives from polygenic determinants. Biochemical, endocrinological, neural processes as well as fat cell morphology work in concert with psychological, social and cultural influences, contributing to obesity (Baum 2008). The relative contribution of each of these causes differs considerably from one obese person to another and remains an issue of much debate. A more compelling question stems from the increasingly accepted view of obesity as not a singular disorder, but many disorders. Accepting this perspective, another challenge becomes identifying subgroups of the obese based on more individually specified causes.

In rats as well as human beings an appetite for protein and a preponderance for fat, increases gradually over the path of the active feeding cycle. This is possible due from the need to enhance nutrient stores in preparation for an inactive period of starvation, such as hibernation or low food supply. This similarity between the rat and human feeding cycle makes rats ideal candidates for experimentation when it come to many treatments for obesity. (See figure 3) Note that the time factor of positive and negative feedback effects produced after the intake of a carbohydrate solutions. When the eating ends the potentials of the positive and negative feedbacks become equal by some function or functions of the central nervous sytem. Here one can see the similarity between the rodent and human population regarding feeding cycles. Gastric banding is certainly one that we can learn much from the rat's reactions as compared to the human nervous system. (Fairburn and Brownell 2002)

Figure 3: (Fairburn and Brownell 2002:12)

The realization that the human and rodent genomes contain large amounts of apparently non-coding DNA sequence, and that random variation in such sequences can be used to track the segregation of specific intervals of DNA, revolutionized genetic mapping by replacing limited phenotypic variants (e.g., blood groups, major histocompatibility complex haplotypes) with a nearly limitless number of genetic polymorphisms that could be used to mark specific sites in the 3 billion base-pair haploid genomes of humans (or mice, rats, pigs, etc.). (Fairburn and Brownell 2002:29)

Literature Review

Assembled under the broad term bariatric surgery, there are a number of surgical procedures whose overall goal is to greatly reduce the stomach's volume, thereby limiting the amount of food one can digest. "Stomach stapling" is often the lay term for the most common of these procedures, but "lap banding" is also quickly gaining popularity. (Hall 2003) Gastric banding (see figure 1), also known as lap band surgery, makes use of an inflatable silicone band to cut off a section of the stomach thereby leaving an very small pouch almost a quarter of the original size. (Mcgowan and Chopra 2004)

Figure 1: Diagram of Gastric Banding ((Mcgowan and Chopra 2004:19)

Another method called Vertical-banded gastroplasty is another purely restrictive procedures in this process the stomach is stapled fairly close to where the esophagus connects to the stomach (see figure 2). The staples are placed in a vertical fashion and a polypropylene band is placed near the bottom of the staple line. (Mcgowan and Chopra 2004)

Figure 2: Vertical-banded gastroplasty (Mcgowan and Chopra 2004:18)

Whichever gastric banding system is chosen it is usually put into place by the use laparascopic surgery around the upper part of the stomach creating the small gastric pouch to limit food consumption and create an earlier feeling of fullness. The band is inflatable and connected to an access port placed close to the skin that allows surgeons to either tighten or loosen the band post surgically to meet patient's requirements. Once the band has been finally adjusted it is inflated with a saline solution. ("Adjustable Stomach Band Approved" 2001) at first, the pouch will fill with only an ounce of food however over time this will stretch to hold approximately four ounces. The patient is required to eat very small meals, chew food thoroughly, and eat slowly. The patient usually discovers that if he or she does not follow those guideline discomfort and vomiting will result (Kral 2001). Generally, patients will accomplish peak weight loss of 44% to 68% of excess weight over a two to three-year period of time (Kaser, & Kukla 2009; Scheen 2001).

However, many scientifically respect journals note that any form of Bariatric surgery is not cosmetic surgery. It is major gastrointestinal procedure that should only be preformed in morbidly obese patients whose obesity puts them at high risk for associated complications and/or death. A standard guideline for when this surgery should be preformed on adults is only when patients are severely obese or their BMI greater than 40 or when they have a BMI greater than 35 together with severe obesity-related health complications. (Caprio 2006) it must be noted that any major surgery also runs the risk of complication as well as death and should not be taken into lightly. In fact surgeons who are excessively promoting the procedure may be increasing the mortality rate of bariatirc surgical patients:

The high estimate of mortality comes from research by David Flum, a University of Washington surgeon who analyzed data for over three thousand patients who underwent gastric bypasses. Flum attributes the high complication rate, in part, to inexperienced surgeons who are eager to add the lucrative but demanding surgery to their repertoire. (Deyo and Patrick 2005:223)

Estimates for the various bariatric surgeries for the severely obese costs between $5,400 and $16,100 for women and $10,700 to $35,600 for men. However, there are alternate therapies that may be considered first. Providing an anti-obesity drug to overweight patients with diabetes has been estimated to cost $8,327. Certain studies have indicated that there may be available a variety of cost-effective anti-obesity interventions (Cawley 2006: 74). Furthermore, extreme obesity usual requires a multi-dsici0plamnry approach and more than surgery is often required to complete the process (Folope, et.al. 2008).

For decades, the psychological literature has promoted a causal link between obesity and psychological problems. Obesity has been attributed to pathologic denial, lack of impulse control, depersonalization, existential vacuum, problems in personality development, and excessive orality. However, the mounting biological evidence brings into question the validity of these etiological theories. In addition, several research studies have found that obese people do not experience any more psychopathology than nonobese people. Melcher and Bostwick 1998)

There is an explosion of bariatric surgery clients. It may be necessary that psychologist or psychotherapists may need to evaluate more fully the eating patterns of these patients prior to surgery. A great deal of the current research suggests that if the psychological matrix of eating disorder can be recognized prior to bariatric surgery, the patient will have a greater chance of long-term success. (Toth and Schwartz 2006) However, some complications can occur with blockage of the band and unfortunately the reservoir implanted beneath the skin doesn't last forever. Consequently, weight regain with this method can also occur. In general gastric banding is no more successful than vertical-banded gastroplasty, and it too can result in iron and vitamin B12 deficiency. (Mcgowan and Chopra 2004)

Just as with vertical-banded gastroplasty, blockage of the band can be problematic, and unfortunately the reservoir implanted beneath the skin doesn't last forever. Consequently, weight regain with this method can also occur. In general gastric banding is no more successful than vertical-banded gastroplasty, and it too can result in iron and vitamin B12 deficiency. (Mcgowan and Chopra 2004:21)

This type of surgery does illicit extremely predictable and repeatable results. "The average weight loss in clinical practice after 2 years for adjustable gastric banding (GB) is 20%, Roux-en-Y gastric bypass (RYGB) is 30% and biliopancreatic diversion or duodenal switch (BPD) is 35%" (Vincent & le Roux 2008: 174). However, a Swedish study designed to compare surgically treated individuals with comparable individuals given conventional weight loss treatment has shown even greater long-term results. The Swedish Obese Subjects Intervention Study (SOS) provides results of large and relatively well-maintained weight losses over a follow-up period of up to eight years. This study was designed to compare surgically treated individuals with comparable individuals given conventional weight loss treatment (Sjostrom, Lissner, Wedel & Sjostrom 1999; Sjostrom, Peltonen & Sjostrom 2001).

At this current time Laparoscopic-adjustable silicone gastric banding (LASGB) is the most common bariatric procedure worldwide. "Along with a significant weight loss and changes in eating behaviour, LASGB has also been proven as an effective surgical procedure in improving obesity-related comorbidities" (Di Somma, et. Al. 2008: 395).

Bariatric surgery is able to improve glucose and lipid metabolism, and cardiovascular function in morbid obesity. (Biliary pancreatic diversion 2009). Par of the aim of this research was also to compare the long-term effects of restrictive (laparoscopic gastric banding, LAGB) procedures on metabolic and cardiovascular parameters, as well as on metabolic syndrome in morbidly obese patients. Another comorbid condition can include pseudotumor cerebri, a condition in which increased intracranial pressure often results in headache and sometimes in vomiting or blurred vision. Pseudotumor cerebri may be difficult to treat and can call for aggressive weight-loss therapy, and actually require bariatric surgery. (Daniels 2006)

Methods & Materials

This study will attempt to create a rat model of adjustable gastric banding. As previously stated in the literature review, rats are an ideal candidate for this model in that their food cycle behavior is identical in many important ways to humans. Especially in regards to the neurotransmitter and hormonal chemical reaction regarding the intake and satiation point of feeding. In order to accomplish this an adjustable gastric banding device with be surgically implanted in the rats. It will contain an inflatable cuff that can be adjusted externally through a typical port. Unlike the permanent setup in humans the port will be used to adjust the band throughout the research to observe the different effects at different band diameters. This will assist the researcher in creating staged reductions of food intake and observe weight loss over a period of several weeks. A modified herpes simplex virus (HSV129) will be used to observe the effect on the neural pathways mediating the balance of food intake. HSV129 will be transported transynaptically into CNS circuitry following injection into the stomach wall underlying the band.

Results

HSV129 labelled neurons were discovered in both the lateral and dorsal hypothalamus, arcuate nucleus as well as in the cerebral cortex. These specific sites were also discovered with feeding related peptides including orexin a and melanin concentrating hormone.

Conclusion

The resultant data recovered from this study show a heightened possibility that adjustable gastric banding has an effect on the sensory nervous system that is directed to the hypothalamus and cortical centre that may indicate a correlative connection between the banding and neuronal behavioral modification. This rodent model will certainly have application with future research in humans. Other animal studies certainly support the existence of a similar thinness or leanness phenotype that is under some genetic and hormonal control. In fact animals can be selectively bred for these traits.

…a substrain of Sprague-Dawley rats has been bred for their resistance to the development of obesity even when maintained on a high-fat diet. In addition, knockout mice created for the RII beta subunit of protein kinase were healthy but had greatly diminished white adi- pose tissue despite normal food intake. These animals were protected against developing diet-induced obesity, thus becoming potential models for the humans in our society who stay thin despite an obesity-promoting environment. (Fairburn and Brownell 2002:23)

Furthermore, the comorbid related traits to obesity have also been observed in rats. For instance, other studies have found that intermittent hypoxia induces a persistent increase in diurnal blood pressure (Robinson and Grunstein 2001). Future research along the lines of obesity and comorbid related diseases will show great promise using rodent models to begin the extremely difficult task of coding the genetic and chemical component of obesity.

List of References

"Adjustable Stomach Band Approved for Severe Obesity." 2001. FDA Consumer, September, p. 4.

'Biliary pancreatic diversion and laparoscopic adjustable gastricbanding in morbid obesity: their long-term effects on metabolicsyndrome and on cardiovascular parameters. 2009.' Cardiovascular Diabetology, 837: 43.

Baum, Fran. 2008. The New Public Health (3rd Ed.) London: Oxford University Press