Results of bariatric surgery

Novel Insight into the Mechanism of Metabolic Surgery Causing the Diversity in Glycemic Status in Type 2 Diabetes

Metabolic surgery results in diverse glycemic status in patients with type 2 diabetes (T2D), including hyperglycemia without remission, significant amelioration of hyperglycemia with partial remission, complete restoration of euglycemia, or with prolonged remission, hyperglycemia recurrence in relapses after remission, or post-bariatric hypoglycemia. Unfortunately, it is not known how metabolic surgery leads to this diverse consequence. Here, we discuss the diversity of glycemic status associated with metabolic surgery and the potential mechanisms of T2D remission. We also highlight the relationship between the change in low-grade inflammation and T2D remission after metabolic surgery. We hypothesize that the level of inflammatory and anti-inflammatory cytokines controls the efficacy of metabolic surgery in patients with T2D. This hypothesis may provide further insight into the mechanism of the beneficial effects of metabolic surgery patients with T2D.

Impact of age on postoperative complications following bariatric surgery

Background: The impact of age on complications following bariatric surgery remains unclear. Research is therefore warranted among previously unstudied populations of bariatric surgery patients. The aim of the current study was to assess the impact of age on postoperative complications following bariatric surgery in Saudi Arabia. Methods: This retrospective study included 301 patients who underwent bariatric surgery between January 2011 and July 2016. Patients were classified into three groups according to age: < 25 years; 25–36 years; and >36 years. Primary outcomes were determined by identifying the number of complications reported during a period of 180 days. The negative binomial model was used to assess the relationship between age and the high rate of postoperative complications following adjustment for confounding variables. Results: The incidence of overall complications was 10.1% in the < 25-year age group, 15% in the 25–36-year age group, and 24.2% in the >36-year age group. After adjusting for confounding variables, it was discovered that the risk of postoperative complications increases with age. The risk was higher in the >36-year age group than in the >25-year age group [adjusted relative rate (aRR) = 2.35; 95% confidence interval (CI) = 1.046–5.290; p = 0.039]. Diabetes (aRR = 3.27), adjustable gastric bands (aRR = 3.40), and a more lengthy hospital stay (aRR = 1.23) were associated with increased rates of postoperative complications. Conclusion: Age is independently associated with a high rate of postoperative complications following bariatric surgery. The results showed that patients with diabetes, those using adjustable gastric bands, and those with longer length of hospital stay had significantly higher incidence of postoperative complications. These findings indicate the need for risk stratification tools to evaluate patients as candidates for bariatric surgery and to use as a guide for identifying optimal preoperative factors.

Non-alcoholic fatty pancreas disease - practices for clinicians

Obesity is a growing health burden worldwide, increasing the risk for several diseases featuring the metabolic syndrome - type 2 diabetes mellitus, dyslipidemia, non-alcoholic fatty liver disease and cardiovascular diseases. With the increasing epidemic of obesity, a new pathologic condition has emerged as a component of the metabolic syndrome - that of non-alcoholic fatty pancreas disease (NAFPD). Similar to non-alcoholic fatty liver disease (NAFLD), NAFPD comprises a wide spectrum of disease - from deposition of fat in the pancreas - fatty pancreas, to pancreatic inflammation and possibly pancreatic fibrosis. In contrast with NAFLD, diagnostic evaluation of NAFPD is less standardized, consisting mostly in imaging methods. Also the natural evolution of NAFPD and its association with pancreatic cancer is much less studied. Not least, the clinical consequences of NAFPD remain largely presumptions and knowledge about its metabolic impact is limited. This review will cover epidemiology, pathogenesis, diagnostic evaluation tools and treatment options for NAFPD, with focus on practices for clinicians.

Hepatic complications of obesity

Obesity is associated with a spectrum of chronic liver disease. Because obesity increases the risk for advanced forms of liver disease (ie, cirrhosis and liver cancer), the obesity epidemic is emerging as a major factor underlying the burden of liver disease in the United States and many other countries. This article reviews mechanisms that mediate the pathogenesis of obesity-related liver disease, summarizes clinical evidence that demonstrates obesity-related liver disease can be life-threatening, and discusses whether or not treatments for obesity or related comorbidities impact liver disease outcomes.

Early insulin sensitivity after restrictive bariatric surgery, inconsistency between HOMA-IR and steady-state plasma glucose levels

BACKGROUND

The low-grade inflammatory condition present in morbid obesity is thought to play a causative role in the pathophysiology of insulin resistance (IR). Bariatric surgery fails to improve this inflammatory condition during the first months after surgery. Considering the close relation between inflammation and IR, we conducted a study in which insulin sensitivity was measured during the first months after bariatric surgery. Different methods to measure IR shortly after bariatric surgery have given inconsistent data. For example, the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) levels have been reported to decrease rapidly after bariatric surgery, although clamp techniques have shown sustained insulin resistance. In the present study, we evaluated the use of steady-state plasma glucose (SSPG) levels to assess insulin sensitivity 2 months after bariatric surgery.

METHODS

Insulin sensitivity was measured using HOMA-IR and SSPG levels in 11 subjects before surgery and at 26% excess weight loss (approximately 2 months after restrictive bariatric surgery).

RESULTS

The SSPG levels after 26% excess weight loss did not differ from the SSPG levels before surgery (14.3 +/- 5.4 versus 14.4 +/- 2.7 mmol/L). In contrast, the HOMA-IR values had decreased significantly (3.59 +/- 1.99 versus 2.09 +/- 1.02).

CONCLUSION

During the first months after restrictive bariatric surgery, we observed a discrepancy between the HOMA-IR and SSPG levels. In contrast to the HOMA-IR values, the SSPG levels had not improved, which could be explained by the ongoing inflammatory state after bariatric surgery. These results suggest that during the first months after restrictive bariatric surgery, HOMA-IR might not be an adequate marker of insulin sensitivity.

Lipoprotein lipase but not hormone-sensitive lipase activities achieve normality after surgically induced weight loss in morbidly obese patients

BACKGROUND

Although bariatric surgery is currently the most common practice for inducing weight loss in morbidly obese patients (BMI>40 kg/m2), its effect on the lipid content of adipose tissue and its lipases (lipoprotein lipase [LPL] and hormone-sensitive lipase [HSL]) are controversial.

METHODS

We analyzed LPL and HSL activities and lipid content from plasma as well as subcutaneous (SAT) and visceral (VAT) adipose tissue of 34 morbidly obese patients (MO) before and after (6 and 12 months) Roux-en-Y gastric bypass surgery and compare the values with those of normal weight (control) patients.

RESULTS

LPL activity was significantly higher in MO (SAT=32.9+/-1.0 vs VAT=36.4+/-3.3 mU/g tissue; p<0.001) than in control subjects (SAT=8.2+/-1.4 vs VAT=6.8+/-1.0 mU/g tissue) in both adipose depots. HSL activity had similar values in both types of tissue (SAT=32.8+/-1.6 and VAT=32.9+/-1.6 mU/g) of MO. In the control group, we found similar results but with lower values (SAT=11.9+/-1.4 vs VAT=12.1+/-1.4 mU/g tissue). Twelve months after surgery, SAT LPL activity diminished (9.8+/-1.4 mU/g tissue, p<0.001 vs morbidly obese), while HSL (46.6+/-3.7 mU/g tissue) remained high. All lipids in tissue and plasma diminished after bariatric surgery except plasma nonesterified fatty acids, which maintained higher levels than controls (16+/-3 vs 9+/-0 mg/dL; p<0.001, respectively).

CONCLUSIONS

When obese patients lose weight, they lose not only part of the lipid content of the cells but also the capacity to store triacylglycerides in SAT depots.

Inflammatory Disease Processes and Interactions with Nutrition

Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain ω-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (ω-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.

Lipoprotein lipase expression in livers of morbidly obese patients could be responsible for liver steatosis

BACKGROUND

Most patients with morbid obesity develop non-alcoholic fatty liver disease (NAFLD). The origins of lipid deposition in the liver and the effects of bariatric surgery in the obese with NAFLD are controversial.

METHODS

We analyzed lipids and lipoprotein lipase (LPL) in both plasma and liver biopsies performed before and 12-18 months after Roux-en-Y gastric bypass surgery in 26 patients.

RESULTS

In the livers of morbidly obese patients, the levels of LPL messenger RNA (mRNA) were higher (4.5-fold) before surgery than afterwards than control livers. In these patients, LPL activity was also significantly higher (91 +/- 7 mU/g) than in controls (51 +/- 3 mU/g, p = 0.0026) and correlated with the severity of the liver damage. All hepatic lipids were significantly increased in obese patients; however, after bariatric surgery, these lipids, with the exception of NEFA, tended to recover to normal levels.

CONCLUSIONS

The liver of obese patients presented higher LPL activity than controls, and unlike the controls, this enzyme could be synthesized in the liver because it also present LPL mRNA. The presence of the LPL activity could enable the liver to capture circulating triacylglycerides, thus favoring the typical steatosis observed in these patients.

Increased expression and activity of hepatic lipase in the liver of morbidly obese adult patients in relation to lipid content

BACKGROUND

The types and sources of lipid deposition in the liver of most patients with morbid obesity, as well as the effects of bariatric surgery, are discussed.

METHODS

In 26 patients with morbid obesity who underwent bariatric surgery, we analyzed different kinds of lipids and hepatic lipase (HL) from both plasma and liver biopsies performed 12-18 months after surgery.

RESULTS

The HL activity and HL-mRNA in morbidly obese (MO) livers were high (258 +/- 17 mU/g, and 4.5-fold, respectively); after surgery, the activity decreased (137 +/- 15 mU/g, p < 0.001) but not the levels of HL-mRNA (4.3-fold). Plasma HL activity was also high (4.31 +/- 0.94 mU/mL plasma), and it decreased during weight loss (2.01 +/- 0.29 mU/mL, p < 0.01); moreover, it correlated (r = 0.3694, p < 0.05) with decreased liver HL activity. Adrenocorticotropic hormone in MO was higher (27 +/- 3 pg/mL) than after surgery (13 +/- 1 pg/mL, p < 0.001). All hepatic and plasma lipids were significantly increased in MO patients, but, after bariatric surgery, most of those parameters recovered or normalized. Liver HL activity correlated with total and esterified cholesterol (r = 0.4399, p < 0.001 and r = 0.4395, p < 0.01, respectively).

CONCLUSION

High HL in MO patients could allow for liver intake of cholesterol that could be re-exported to steroidogenic organs to synthesize steroidal hormones. A decrease of plasma HL during weight loss could be a good index for improvement of liver disease.

Increased colorectal epithelial cell proliferation and crypt fission associated with obesity and roux-en-Y gastric bypass

BACKGROUND AND AIMS

The relationship between obesity, weight reduction, and future risk of colorectal cancer is not well understood. Therefore, we compared mucosal biomarkers in normal weight individuals [body mass index (BMI), 18.5-24.9 kg/m(2)] with those in morbidly obese patients (BMI >40 kg/m(2)) before and 6 months after Roux-en-Y gastric bypass (RYGB).

METHODS

Rectal epithelial cell mitosis, crypt area, and crypt branching were measured following whole crypt microdissection. Apoptosis was measured by immunohistochemistry for neo-cytokeratin 18 on fixed tissue sections. Serum levels of C-reactive protein and cytokines were assayed in combination with quantification of mucosal proinflammatory gene expression by real-time RT-PCR.

RESULTS

Twenty-six morbidly obese patients (mean BMI, 54.4 kg/m(2)) had significantly increased mitosis, crypt area, and crypt branching (all P < 0.01) compared with 21 age- and sex-matched normal weight individuals (mean BMI, 22.5 kg/m(2)). Morbidly obese patients underwent a mean excess weight loss of 41.7% at a mean of 26 weeks after RYGB. Surprisingly, this was associated with a further increase in mitosis and decreased apoptosis of epithelial cells. At the same time, lower levels of serum C-reactive protein and interleukin-6 following RYGB were accompanied by a reduction in mucosal IL-6 protein content but elevated mucosal expression of other proinflammatory genes such as cyclooxygenase-1 and cyclooxygenase-2.

CONCLUSIONS

Mucosal biomarkers, accepted as indicators of future colorectal cancer risk, are increased in morbidly obese patients compared with normal weight controls. The hyperproliferative state that exists 6 months after RYGB may have important implications for long-term colorectal cancer risk in bariatric surgery patients.

The comparative effects of bariatric surgery on weight and type 2 diabetes

BACKGROUND

Epidemiological evidence confirms that risk of developing type 2 diabetes is related to weight gain. Weight reduction is beneficial as relative risk is reduced to 0.13 for weight loss >20 kg. This raises the question of effectiveness of bariatric surgery on 1) weight loss and 2) diabetes-related outcomes in morbidly obese patients.

METHODS

We reviewed the literature using Medline. Only 2 meta-analyses reporting on both outcomes were included, as well as 50 systematic reviews or primary studies.

RESULTS

Meta-analyses mainly based on case series data as well as controlled studies confirm that bariatric surgery is highly effective in obtaining weight reduction in morbidly obese patients up to 60% of the excess weight, along with resolution of preoperative diabetes in more than 75% of cases. Among bariatric surgery techniques, malabsorptive procedures (biliopancreatic diversion and gastric bypass) appear to be more effective on both outcomes than restrictive procedures (gastroplasty and gastric banding).

CONCLUSION

Even if more studies are needed to confirm current evidence, bariatric surgery is effective for controlling diabetes. It appears as an efficient strategy from economic modeling due to savings from reduction in diabetes-related costs.

Short-term overfeeding induces insulin resistance in weight-stable patients after bariatric surgery

BACKGROUND

Short time overfeeding of rats rapidly leads to insulin resistance (IR). A study with healthy human volunteers, which we suggest are less susceptible for developing IR after short time overfeeding, did not show these effects on IR. Therefore a study population of weight-stable, former morbidly obese subjects (BMI 31.3 kg/m2), which were treated with bariatric surgery approximately 3 years ago was selected.

METHODS

Eleven subjects were submitted to a 7-day overfeeding study, resulting in a 53% increase in caloric intake (1,227 +/- 394.4 to 1,879.2 +/- 298.4 kcal/day). During normal diet and after overfeeding, insulin sensitivity was measured using steady state plasma glucose (SSPG) levels. At these time points, BMI and waist/hip ratio together with plasma levels of inflammatory markers (CRP, AGP, LBP, and TNF-alpha receptors) and plasma leptin values were also measured.

RESULTS

SSPG levels after overfeeding increased from 8.2 +/- 3.2 to 10.6 +/- 2.6 mmol/l (P < 0.05), indicating decreased insulin sensitivity after overfeeding. Fasting plasma insulin, glucose, circulating levels of inflammatory markers, BMI, and waist/hip ratio remained unchanged.

CONCLUSIONS

This study shows that overfeeding in a group of weight-stable, former morbidly obese subjects 3 years after bariatric surgery results in decreased insulin sensitivity. The mechanisms behind decreased insulin sensitivity induced by overfeeding are poorly understood, but the present results reveal that a unique human model is available to study these mechanisms, leading to a better understanding of the pathophysiology of IR.

Predicting maximum Roux-en-Y gastric bypass-induced weight reduction--preoperative plasma leptin or body weight?

BACKGROUND

Weight loss after bariatric surgery varies between patients, and predicting the extent thereof is often inaccurate. The aim of this study was to assess the potential of preoperative plasma leptin and body weight in predicting the maximum weight loss within 2 years after Roux-en-Y gastric bypass (RYGBP).

METHODS

The study comprised 68 subjects (39 women, 29 men; mean age 36.4 +/- 10.2 years, body weight 130.3 +/- 24.8 kg, BMI 44.4 +/-6.8 kg/m2) undergoing RYGBP who were followed for 2 years. Baseline and maximum follow-up plasma leptin and weight were assessed.

RESULTS

Mean maximum weight reduction of 50.5 +/- 19.1 kg (38.0 +/- 9.0%, range 24-100 kg) was noted at 15 +/- 4 months after RYGBP. Baseline plasma leptin was 37.9 +/- 14.5 ng/ml, and decreased to 17.4 +/- 8.1 ng/ml (P < 0.001) at maximum weight reduction. No significant correlation between baseline plasma leptin and absolute or relative weight reduction or minimum body weight achieved was noted. No significant plasma leptin threshold which would be predictive for any consistent extent of weight loss was found. However, baseline body weight was a strong determinant of minimum body weight attained (r = 0.67; P < 0.01) and of maximum absolute weight reduction (r = 0.81; P < 0.01).

CONCLUSION

Preoperative plasma leptin concentration cannot be used as a predictor of weight reduction following RYGBP. Preoperative body weight is a reliable predictor of post-RYGBP weight loss.