Association of central sensitization, visceral fat, and surgical outcomes in lumbar spinal stenosis.

BACKGROUND: Controversy remains regarding predictors of surgical outcomes for patients with lumbar spinal stenosis (LSS). Pain sensitization may be an underlying mechanism contributing to LSS surgical outcomes. Further, obesity is associated with dissatisfaction and poorer outcomes after surgery for LSS. Therefore, this study aimed to examine the relationship between central sensitization (CS), visceral fat, and surgical outcomes in LSS. METHODS: Patients with LSS were categorized based on their central sensitization inventory (CSI) scores into low- (CSI < 40) and high- (CSI ≥ 40) CSI subgroups. The participants completed clinical outcome assessments preoperatively and 12 months postoperatively. RESULTS: Overall, 60 patients were enrolled in the study (28 men, 32 women; mean age: 62.1 ± 2.8 years). The high-CSI group had significantly higher mean low back pain (LBP), leg pain, and leg numbness visual analogue scale (VAS) scores than the low-CSI group (p < 0.01). The high-CSI group had a significantly higher mean visceral fat area than the low-CSI group (p < 0.01). Postoperatively, LBP VAS score was significantly worse in the high-CSI group. Relative to preoperatively, postoperative leg pain and leg numbness improved significantly in both groups. CONCLUSIONS: We believe that neuro decompression can be effective for LSS surgical outcomes in patients with CS; nonetheless, it should be approached with caution owing to the potential for worsening LBP. Additionally, visceral fat is an important indicator suggesting the involvement of CS.

High visceral fat-to-muscle ratio predicated a recurrent fistula after definitive surgery for a small intestinal fistula with diffuse extensive abdominal adhesions: a cohort study.

BACKGROUND: In patients diagnosed with sarcopenia, the presence of chronic preoperative inflammation, assessed by the ratio of the visceral fat area (VFA) to the total abdominal muscle area index (TAMAI) (VFA/TAMAI), has been found to adversely affect wound healing. An elevated VFA/TAMAI may contribute to a higher incidence of postoperative recurrent fistulas (RFs) following definitive surgery (DS) for small intestinal fistulas accompanied by diffuse extensive abdominal adhesions. The objective of this study was to evaluate the predictive value of VFA/TAMAI for postoperative RFs. METHODS: The study enrolled 183 sarcopenic patients, with a median age of 51 years [interquartile range (IQR): 38-61 years), a median body mass index of 19.6 kg/m 2 (IQR: 18.9-21.0 kg/m 2 ) who underwent DS for small intestinal fistulas between January 2018 and October 2022 were included in the multicenter study. The outcomes assessed were RFs and postoperative length of stay (LOS). VFA/TAMAI was examined as a potential risk factor for each outcome. RESULTS: Out of the 183 patients, 20.2% ( n =37) developed RFs. The multivariate regression analysis identified VFA/TAMAI as the sole factor associated with RFs [odds ratio=1.78, 95% confidence interval (CI): 1.09-2.87, P =0.02]. The multivariable Cox regression analysis demonstrated that an elevated VFA/TAMAI was linked to a reduced postoperative LOS (hazard ratio=0.69, 95% CI: 0.59-0.81, P <0.001). CONCLUSION: In sarcopenic patients, a high VFA/TAMAI predicated the occurrence of RFs after DS for small intestinal fistulas in the presence of diffuse extensive abdominal adhesions.

Risk factor analysis of postoperative pancreatic fistula after distal pancreatectomy, with a focus on pancreas-visceral fat CT value ratio and serrated pancreatic contour.

BACKGROUND: In pancreaticoduodenectomy, the pancreas-visceral fat CT value ratio and serrated pancreatic contour on preoperative CT have been revealed as risk factors for postoperative pancreatic fistulas. We aimed to evaluate whether they could also serve as risk factors for postoperative pancreatic fistulas after distal pancreatectomy. METHODS: A total of 251 patients that underwent distal pancreatectomy at our department from 2006 to 2020 were enrolled for the study. We retrospectively analyzed risk factors for postoperative pancreatic fistulas after distal pancreatectomy using various pre and intraoperative factors, including preoperative CT findings, such as pancreas-visceral fat CT value ratio and serrated pancreatic contour. RESULTS: The study population included 147 male and 104 female participants (median age, 68 years; median body mass index, 21.4 kg/m2), including 64 patients with diabetes mellitus (25.5%). Preoperative CT evaluation showed a serrated pancreatic contour in 80 patients (31.9%), a pancreatic thickness of 9.3 mm (4.0-22.0 mm), pancreatic parenchymal CT value of 41.8 HU (4.3-22.0 HU), and pancreas-visceral fat CT value ratio of - 0.41 (- 4.88 to - 0.04). Postoperative pancreatic fistulas were developed in 34.2% of the patients. Univariate analysis of risk factors for postoperative pancreatic fistulas showed that younger age (P = 0.005), high body mass index (P = 0.001), absence of diabetes mellitus (P = 0.002), high preoperative C-reactive protein level (P = 0.024), pancreatic thickness (P < 0.001), and high pancreatic parenchymal CT value (P = 0.018) were significant risk factors; however, pancreas-visceral fat CT value ratio (P = 0.337) and a serrated pancreatic contour (P = 0.122) did not serve as risk factors. Multivariate analysis showed that high body mass index (P = 0.032), absence of diabetes mellitus (P = 0.001), and pancreatic thickness (P < 0.001) were independent risk factors. CONCLUSION: The pancreas-visceral fat CT value ratio and serrated pancreatic contour evaluated using preoperative CT were not risk factors for postoperative pancreatic fistulas after distal pancreatectomy. High body mass index, absence of diabetes mellitus, and pancreatic thickness were independent risk factors, and a close-to-normal pancreas with minimal fat deposition or atrophy is thought to indicate a higher risk of postoperative pancreatic fistulas after distal pancreatectomy.

Visceral adipose tissue is a better predictor than BMI in the alternative Fistula Risk Score in patients undergoing pancreatoduodenectomy.

BACKGROUND: Muscle attenuation (MA) and visceral adipose tissue (VAT) have not yet been included in the currently used alternative Fistula Risk Score (a-FRS). The aim of this study was to examine the added value of these parameters as predictors of clinically relevant postoperative pancreatic fistula (CR-POPF) in the a-FRS after pancreatoduodenectomy compared to Body Mass Index (BMI). METHODS: A single center retrospective cohort study was performed in patients who underwent pancreatoduodenectomy between 2009 and 2018. The a-FRS model was reproduced, MA and VAT were both combined and separately added to the model instead of BMI using logistic regression analysis. Model discrimination was assessed by ROC-curves. RESULTS: In total, 329 patients were included of which 55 (16.7%) developed CR-POPF. The a-FRS model showed an AUC of 0.74 (95%CI: 0.68-0.80). In this model, BMI was not significantly associated with CR-POPF (p = 0.16). The MA + VAT model showed an AUC of 0.81 (95%CI: 0.75-0.86). VAT was significantly associated with CR-POPF (per cm2, OR: 1.01; 95%CI: 1.00-1.01; p < 0.001). The AUC of the MA + VAT model differed significantly from the AUC of the a-FRS model (p = 0.001). CONCLUSION: Visceral adipose tissue is of added value in the a-FRS compared to BMI in predicting CR-POPF in patients undergoing pancreatoduodenectomy.

Dopamine D2 receptor agonist, bromocriptine, remodels adipose tissue dopaminergic signalling and upregulates catabolic pathways, improving metabolic profile in type 2 diabetes.

BACKGROUND AND OBJECTIVES: The therapeutic effects of the dopamine D2 receptor (D2R) agonist, bromocriptine, in type 2 diabetes (T2D) have been attributed to central nervous system actions. However, peripheral dopamine directly modulates glucose uptake in insulin-sensitive tissues and lipid metabolism in adipose tissue (AT). We hypothesized that the dopaminergic system may be impaired in the adipose tissue of patients with T2D and that the therapeutic actions of bromocriptine could involve the modulation of metabolism in this tissue. METHODS: The expression of dopamine receptors was evaluated in visceral AT samples from patients with obesity and stratified in several groups: insulin sensitive (IS); insulin resistance (IR) normoglycaemic; insulin resistant prediabetic; insulin resistant diabetic, according to Ox-HOMA2IR, fasting glycaemia and HbA1c levels. T2D Goto-Kakizaki rats (GK) were fed a high-caloric diet (HCD) for five months and treated with bromocriptine (10 mg/kg/day, i.p.) in the last month. The levels of dopaminergic system mediators and markers of insulin sensitivity and glucose and lipid metabolism were assessed in the peri-epididymal adipose tissue (pEWAT) and brown (BAT) adipose tissues, liver, and skeletal muscle. RESULTS: Patients with IR presented a decreasing trend of DRD1 expression in the visceral adipose tissue, being correlated with the expression of UCP1, PPARA, and insulin receptor (INSR) independently of insulin resistance and body mass index. Although no differences were observed in DRD2, DRD4 expression was significantly decreased in patients with prediabetes and T2D. In HCD-fed diabetic rats, bromocriptine increased D1R and tyrosine hydroxylase (TH) levels in pEWAT and the liver. Besides reducing adiposity, bromocriptine restored GLUT4 and PPARγ levels in pEWAT, as well as postprandial InsR activation and postabsorptive activation of lipid oxidation pathways. A reduction of liver fat, GLUT2 levels and postprandial InsR and AMPK activation in the liver was observed. Increased insulin sensitivity and GLUT4 levels in BAT and an improvement of the overall metabolic status were observed. CONCLUSIONS: Bromocriptine treatment remodels adipose tissue and the liver dopaminergic system, with increased D1R and TH levels, resulting in higher insulin sensitivity and catabolic function. Such effects may be involved in bromocriptine therapeutic effects, given the impaired expression of dopamine receptors in the visceral adipose tissue of IR patients, as well as the correlation of D1R expression with InsR and metabolic mediators.

Surgical ablation of whitened interscapular brown fat ameliorates cardiac pathology in salt-loaded metabolic syndrome rats.

Brown adipose tissue (BAT) is an endocrine organ that contributes to thermogenesis and energy consumption. We investigated the effects of salt loading and surgical removal of whitened interscapular BAT (iBAT) on cardiac and adipose tissue pathology in DahlS.Z-Leprfa /Leprfa (DS/obese) rats, an animal model of metabolic syndrome (MetS). DS/obese rats were subjected to surgical removal of iBAT or sham surgery at 8 weeks of age and were provided with drinking water containing or not containing 0.3% NaCl for 4 weeks beginning at 9 weeks of age. Removal of iBAT suppressed the salt-induced exacerbation of left ventricular inflammation, fibrosis, and diastolic dysfunction, but not that of hypertension development, in DS/obese rats. Salt loading attenuated adipocyte hypertrophy but enhanced inflammation in both visceral white adipose tissue (WAT) and iBAT. Although iBAT removal did not affect visceral WAT pathology in salt-loaded DS/obese rats, it attenuated the elevation of circulating interleukin-6 levels in these animals. Downregulation of uncoupling protein-1 expression in iBAT of DS/obese rats was not affected by salt loading. Our results suggest that the conversion of iBAT to WAT-like tissue contributes to a salt-induced elevation of circulating proinflammatory cytokine levels that leads to exacerbation of cardiac pathology in this model of MetS.

Clinical predictors and significance of adherent perinephric fat assessed with Mayo Adhesive Probability (MAP) score and perinephric fat surface density (PnFSD) at the time of partial nephrectomy for localized renal mass. A single high-volume referral center experience.

BACKGROUND: Adherent perinephric fat (APF) could negatively influence surgical outcomes of partial nephrectomy (PN). Novel radiological scores have been introduced to preoperatively detect APF, i.e. Mayo Adhesive Probability (MAP) score and perinephric fat surface density (PnFSD). We aimed to evaluate clinical predictors of APF and the association of MAP and PnFSD with perioperative outcomes after PN. METHODS: Clinical and radiological data of patients undergoing open or robotic PN were prospectively gathered. Perinephric fat was retrospectively measured by a single expert uro-radiologist. Patients were divided into MAP 0-3 vs. MAP 4-5 and high vs. low PnFSD. Multivariable analysis was performed to seek for clinical predictors of APF. RESULTS: Overall, 175 patients were entered. Patients with vs. without APF were significantly different regarding age, gender, ASA score, Charlson Comorbidity Index, Body Mass Index, waist circumference, HDL status and metabolic syndrome. Conversely, tumor-related characteristics were not significantly different between the groups. At multivariable analysis, metabolic syndrome was confirmed as the only independent predictor of APF (OR: 24.9; P<0.001). Notably, APF assessed by MAP score or PnFSD was not associated with perioperative outcomes after PN. CONCLUSIONS: In experienced hands, APF did not impact on intra- or perioperative outcomes after PN. Metabolic syndrome was the only significant predictor of APF in our series.

Mechanism of Transplanted Islet Engraftment in Visceral White Adipose Tissue.

BACKGROUND: White adipose tissue (WAT) is a candidate transplantation site for islets. However, the mechanism of islet engraftment in WAT has not been fully investigated. In this study, we attempted to clarify the therapeutic effect and mechanism of islet transplantation into visceral WAT. METHODS: Two hundred mouse islets were transplanted into epididymal WAT of syngeneic diabetic mice by wrapping islets with the tissue (fat-covered group). Mice that received intraperitoneal and renal subcapsular islet transplantations were used as negative and positive control groups, respectively. RESULTS: The transplant efficacy, including improvements in blood glucose and plasma insulin levels and in glucose tolerance tests, of the fat-covered group was superior to the negative control group and almost equal to the positive control group. Vessel density of engrafted islets in the fat-covered group was higher than that in the positive control group. It was speculated that the mechanism of islet engraftment in WAT might consist of trapping islets in WAT, adhesion of islets via a combination of adhesion factors (fibronectin and integrin ß1), and promotion of angiogenesis in islets by expression of angiogenic factors induced by adiponectin. CONCLUSIONS: Visceral WAT is an important candidate for islet transplantation. Adhesion factors and adiponectin might contribute to islet engraftment into WAT. Further studies to elucidate the detailed mechanism are necessary.

Use of endoscopic tissue morcellator in removing retroperitoneal fat in retroperitoneoscopic radical nephrectomy.

BACKGROUND: Evaluate the safety and effectiveness of using an endoscopic tissue morcellator (ETM) to remove the retroperitoneal fat during retroperitoneoscopic radical nephrectomy (RRN). METHODS: The use of ETM in the removal of retroperitoneal fat was retrospectively analyzed in patients who underwent RRN for localized renal cancer in our hospital from January 2010 to January 2018. We accrued the appropriate patients and divided them into two groups. The first group included patients of RRN where ETM was used to remove the retroperitoneal fat, while the second group was comprised of patients of RRN where ETM was not performed, which served as the control group. Each group was further divided into two subgroups, including obese patients (BMI ≥ 28) and patients suffering from high-volume renal cancer (Stage T2a). The differences between the two groups as well as their subgroups were analyzed and statistically compared. RESULTS: All 222 nephrectomies were completed under retroperitoneoscopy, ETM was used in 105 of these 222 patients. Among them, 31 cases were of obese patients, and 26 cases were of high-volume renal cancer patients. The other 117 patients had undergone RRN without the use of ETM. Among them, 36 cases were of obese patients, and 28 cases were of high-volume renal cancer patients. The differences in age, BMI, tumor position, and tumor size between the two groups were not statistically significant, P > 0.05. Both the surgical time and the blood loss for the ETM group were significantly lower than the control group, p < 0.05. In the subgroup analysis, the obese patients and patients with high tumor volume also showed a significantly lower surgical time and less blood loss, p < 0.05. The postoperative hospitalization time, the total survival rate, and the disease-free survival rate were not statistically significant, p > 0.05. CONCLUSIONS: The use of ETM in removing the retroperitoneal fat during the RRN can potentially reduce the surgical time and lessen the blood loss. This technique is especially advantageous for obese and large-volume tumor patients.

Adherent Perinephric Fat Is a Surgical Risk Factor in Laparoscopic Single-Site Donor Nephrectomy: Analysis Using Mayo Adhesive Probability Score.

BACKGROUND: The host-related risk factors for surgical difficulty of partial nephrectomy include the presence of thick and adherent adipose tissue surrounding the kidney (adherent perinephric fat [APF]). The kidney and perirenal fat must be isolated in donor nephrectomy. Thus, APF is an important surgery-related factor. We analyzed whether the Mayo adhesive probability (MAP) score is related to APF and surgical outcomes in laparoscopic single-site donor nephrectomy (LESS-DN). METHODS: Forty-six donors who underwent LESS-DN were selected. Determination of APF was based on a retrospective review of video-recorded surgical procedures during anterior perinephric fat dissection. The MAP score was evaluated from computed tomography images. Data regarding patient characteristics and operative outcomes were collected. We then examined the MAP score, APF, and related factors. RESULTS: Eleven patients (23.9%) had APF. The patients were divided into 2 groups (MAP score of 0 points and ≥ 1 point). The 2 groups showed significant differences in sex, age, body mass index, history of hypertension, and history of dyslipidemia. The operation time was significantly longer and the estimated blood loss volume was higher in patients with a MAP score of ≥ 1. Eight of 9 patients with a MAP score of ≥ 1 had APF. The only significant differences between patients with and without APF were in the body mass index, history of hypertension, and history of dyslipidemia. The operation time was significantly longer and the estimated blood loss volume was larger in patients with APF. CONCLUSIONS: The MAP score could be useful when predicting surgical difficulty in patients undergoing LESS-DN.

Increased plasmatic NETs by-products in patients in severe obesity.

Neutrophil extracellular traps (NETs) are DNAs products involved in immune process. Obesity through a low-grade chronic inflammation determines neutrophil activation, but it is still unclear its role in NETs formation. Here we analyzed the NETs levels in healthy and morbid obese, their association with anthropometric and glyco-metabolic parameters and their changes after bariatric surgery. For this study, we enrolled 73 patients with morbid obesity (BMI ≥40 kg/m2 or ≥35 kg/m2 + comorbidity) eligible to sleeve gastrectomy. In parallel, 55 healthy subjects and 21 patients with severe coronary artery disease were studied as controls. We evaluated anthropometric parameters, peripheral blood pressure, biochemical and serum analysis at the enrollment and at twelve months after surgery. Plasmatic levels of MPO-DNA complexes were assessed by ELISA. NETs levels were higher in obese than in control group (p < 0.001) and correlated with the main anthropometric variable (BMI, waist, hip), glyco-metabolic variables and systolic blood pressure. NETs trend after intervention was uneven. The reduction of NETs correlated with the entity of reduction of BMI (ρ = 0.416, p < 0.05), visceral fat area (ρ = 0.351, p < 0.05), and glycemia (ρ = 0.495, p < 0.001). In medical history of patients in whom NETs increased, we observed a higher number of thromboembolic events. Our observations indicate that severe obesity is associated with increased generation of NETs, which in turn could influence the patients' systemic inflammatory state. Weight loss and in particular, loss of adipose tissue after bariatric surgery does not in itself correct NET's dysregulated production. Finally, patients in whom NETs accumulation persists after surgery are probably those at the highest risk of cardiovascular events.

Coronary disease is not associated with robust alterations in inflammatory gene expression in human epicardial fat.

Epicardial adipose tissue (EAT) is the visceral fat depot of the heart. Inflammation of EAT is thought to contribute to coronary artery disease (CAD). Therefore, we hypothesized that the EAT of patients with CAD would have increased inflammatory gene expression compared with controls without CAD. Cardiac surgery patients with (n = 13) or without CAD (n = 13) were consented, and samples of EAT and subcutaneous adipose tissue (SAT) were obtained. Transcriptomic analysis was performed using Affymetrix Human Gene 1.0 ST arrays. Differential expression was defined as a 1.5-fold change (ANOVA P < 0.05). Six hundred ninety-three genes were differentially expressed between SAT and EAT in controls and 805 in cases. Expression of 326 genes was different between EAT of cases and controls; expression of 14 genes was increased in cases, while 312 were increased in controls. Quantitative reverse transcription PCR confirmed that there was no difference in expression of CCL2, CCR2, TNF-α, IL-6, IL-8, and PAI1 between groups. Immunohistochemistry showed more macrophages in EAT than SAT, but there was no difference in their number or activation state between groups. In contrast to prior studies, we did not find increased inflammatory gene expression in the EAT of patients with CAD. We conclude that the specific adipose tissue depot, rather than CAD status, is responsible for the majority of differential gene expression.

Pelvic fat volume reduction with preoperative very low energy diet (VLED): implications for rectal cancer surgery in the obese.

BACKGROUND: Obese patients have higher complication rates after pelvic surgery. Laparoscopic rectal surgery may not be possible in the obese individual due to mesorectal, total pelvic and general visceral fat volumes. Very low energy diets reduce visceral fat but the changes within the pelvis and mesorectum are unknown. The aim of the present study was to quantify the proportion of fat lost from total pelvic and mesorectal fat with a very low energy diet (VLED) and define simple, accessible measurements that correlate with expected volume reduction. METHODS: A study was conducted on proportion change in mesorectal and intrapelvic fat volumes in patients on a VLED prior to bariatric surgery at the Alfred Hospital in Melbourne. The VLED was a standardized 4-week meal replacement. Proportion change in mesorectal and intrapelvic fat volumes were measured. Patients had standardized pre-diet and post-diet magnetic resonance imaging (MRI) of the pelvis. Body mass index, weight and girth measures were obtained. Adipose quantification analysis was performed using Q-Fat. RESULTS: Nine patients were included in this study, who were preparing for bariatric (not colorectal) surgery (5 females, median age 42 years, range 27-59 years) pre-protocol body mass index was 55.8 (range 39.5-60.6 kg/m2); median weight was 163 kg. Median mesorectal fat reduction was 29.9% (range 11.6-66.6%). Linear regression showed a relationship between the amount of mesorectal fat reduction and two variables: patient height and the distance from S1 to the posterior aspect of the rectum on MRI. The relationship predicted response to the diet (R2 67%, p = 0.040). CONCLUSIONS: Very low energy diets result in a clinically significant reduction in mesorectal fat with a lesser change in total pelvic fat, suggesting that very low energy diets may be useful for preparation for pelvic surgery in the obese. The distance from S1 to the posterior rectum correlates well with mesorectal reduction, making this a valuable clinical tool when volumetric analysis is not possible. This analysis is limited to the quantification of the effect of the diet and cannot comment on the safety of this approach before pelvic cancer surgery.

Acute and longer-term body composition changes after bariatric surgery.

BACKGROUND: Bariatric surgery induces weight loss but its acute and longer-term effects on body composition (BC) are largely unknown. OBJECTIVES: To determine the BC changes in obese French patients after sleeve gastrectomy (SG) at 1 and 12 months. SETTING: Obesity Reference Center, University Hospital of Montpellier, France. METHODS: Whole and localized BC (lean tissue mass [LTM] and fat mass [FM]) and abdominal adiposity, including total adipose tissue, visceral adipose tissue, and subcutaneous adipose tissue, were determined by dual-energy X-ray absorptiometry in 30 obese patients (25 women, 83.3%) just before SG and 1 and 12 months later. RESULTS: The mean weight loss was -9.7 ± 2.6 kg at 1 month and -32.1 ± 10.3 kg at 12 months. This weight loss was due to an equivalent decrease in LTM and FM in the acute phase, while FM loss appeared to be the main cause in the chronic phase. For each component (LTM and FM), the loss was relatively homogeneous across sites. Compared with the presurgical values, android and gynoid tissue and total adipose tissue, visceral adipose tissue, and subcutaneous adipose tissue changed significantly over the 12-month period. No basal clinical parameter was predictive of the variation in LTM, whereas age and the whole-body LTM/FM ratio were associated with the decrease in FM. CONCLUSION: This study demonstrates that SG induces a clear modification in BC, characterized by a decrease in LTM in the acute phase and sustained FM loss in the first year. These results suggest that the early phase should be targeted for strategies to reduce LTM loss, which is a longer-term weight-regain criterion. Further studies to investigate the potential advantages of visceral adipose tissue compared with whole-body FM for improving post-SG co-morbidities should be performed.

Abdominal Ectopic Thyroid Tissue: The Man From Istanbul.

Thyroid ectopia is a rare finding below the diaphragm. It is characterized by normal thyroid parenchyma in unusual locations with preserved thyroid marker immunoreactivity. In this article, we present the first known case of thyroid tissue in the periappendiceal fat and discuss possible ethiopathogenic theories.

Lipectomizing Mice for Applications in Metabolism.

The obesity epidemic is a critical public health problem closely associated with the development of metabolic disease. In obesity there is excess white adipose tissue, a dynamic tissue that has many biological functions. Specifically visceral adipose tissue (VAT) is an active endocrine organ producing hormones that control systemic metabolism. VAT accumulates immune cells that produce cytokines that drive chronic inflammation and promote insulin resistance. VAT can be surgically removed in experimental animals (lipectomy) to explore mechanisms by which VAT participates in metabolic, endocrine, and immunological functions. This chapter describes the technical protocol for efficient and successful removal of the gonadal fat pads in mice.

The effect of omentectomy added to bariatric surgery on metabolic outcomes: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Excess visceral adipose tissue has been identified as an important risk factor for obesity-related co-morbidities. Conflicting information exists on whether omentectomy added to bariatric surgery is beneficial to metabolic variables. OBJECTIVE: To evaluate the impact of omentectomy added to bariatric surgery on metabolic outcomes SETTING: University Hospital, Canada. METHODS: MEDLINE, EMBASE, and PubMed were searched up to May 2018. Studies were eligible for inclusion if they were randomized controlled trials comparing omentectomy added to bariatric surgery with bariatric surgery alone. Primary outcome measures were absolute change in metabolic variables (body mass index, insulin, glucose, cholesterol, lipoproteins, and triglycerides); secondary outcomes were changes in adipocytokines. Pooled mean differences (mean deviation; MD) were calculated using random effects meta-analyses, and heterogeneity was quantified using the I2 statistic. RESULTS: Ten trials involving a total of 366 patients met the inclusion criteria with a median follow-up time of 1 year after surgery. Adding omentectomy to bariatric surgery demonstrated a minimal but statistically significant decrease in body mass index compared with bariatric surgery alone (MD 1.29, 95% confidence interval .35-2.23, P = .007, I2 = 0%, 10 trials). Conversely, patients who underwent bariatric surgery alone had significant increases in high-density lipoprotein (MD -2.12, 95% confidence interval -4.13 to -.11, P = .04, I2 = 0%, 6 trials). Other metabolic outcomes and adipocytokines showed no significant difference between procedures. CONCLUSION: The addition of omentectomy to bariatric surgery results in minimal reduction of body mass index. Considering no overall improvement in metabolic outcomes and the time and effort required, the therapeutic use of omentectomy added to bariatric surgery is not warranted.

Perirenal fat surface area as a risk factor for perioperative difficulties and 30-day postoperative complications in elective colon cancer surgery.

AIM: Visceral obesity is associated with perioperative and postoperative complications in colorectal surgery. We aimed to investigate the association between the perirenal fat surface area (PRF) and postoperative complications. METHOD: Data on 610 patients undergoing curative, elective colon cancer resection between 2006 and 2016 at Stockholm South General Hospital were retrieved from a local quality register. We assessed perioperative and postoperative outcomes using a multinomial regression model adjusted for age, sex, American Society of Anesthesiologists classification and surgical approach (open/laparoscopy) in relation to PRF. RESULTS: PRF could be measured in 605 patients; the median area was 24 cm2 . Patients with PRF ≥ 40 cm2 had longer operation time (median 223 vs 184 min), more intra-operative bleeding (250 vs 125 ml), reoperations (11% vs 6%), surgical complications (27% vs 13%) and nonsurgical infectious complications (16% vs 9%) than patients with PRF < 40 cm2 , but there were no differences in the need for intensive care or duration of hospital stay. The multivariate analyses revealed an increased risk of any complication [OR 1.68 (95% CI 1.1-2.6)], which was even more pronounced for moderate complications [Clavien-Dindo II, OR 2.14 (CI 1.2-2.4]; Clavien-Dindo III, OR 2.35 (CI 1.0-5.5)] in patients with PRF ≥ 40 vs < 40 cm2 . The absolute risk of complications was similar in men and women with PRF ≥ 40 cm2 . CONCLUSION: PRF, an easily measured indirect marker of visceral obesity, was associated with overall and moderate complications in men and women and could serve as a useful tool in the assessment of preoperative risk.

Mesenteric visceral lipectomy using tissue liquefaction technology reverses insulin resistance and causes weight loss in baboons.

BACKGROUND: Visceral obesity is associated with diabetogenic and atherogenic abnormalities, including insulin resistance and increased risk for cardiometabolic diseases and mortality. Rodent lipectomy studies have demonstrated a causal link between visceral fat and insulin resistance, yet human omentectomy studies have failed to replicate this metabolic benefit, perhaps owing to the inability to target the mesentery. OBJECTIVES: We aimed to demonstrate that safe and effective removal of mesenteric fat could be achieved in obese insulin-resistant baboons using tissue liquefaction technology. SETTING: Southwest National Primate Research Center, San Antonio, Texas. METHODS: Tissue liquefaction technology has been developed to enable mesenteric visceral lipectomy (MVL) to be safely performed without disturbing the integrity of surrounding nerves and vessels in the mesentary. After an initial MVL optimization study (n = 3), we then performed MVL (n = 4) or sham surgery (n = 2) in a cohort of insulin-resistant baboons, and the metabolic phenotype was assessed via hyperinsulinemic-euglycemic clamps at baseline and 6 weeks later. RESULTS: MVL led to a 75% improvement in glucose disposal at 6-weeks follow-up (P = .01). Moreover, despite removing only an average of 430 g of mesenteric fat (~1% of total body mass), MVL led to a 14.4% reduction in total weight (P = .001). Thus, these data demonstrate that mesenteric fat can be safely targeted for removal by tissue liquefaction technology in a nonhuman primate, leading to substantial metabolic improvements, including reversal of insulin resistance and weight loss. CONCLUSIONS: These data provide the first demonstration of successful adipose tissue removal from the mesentery in a mammal. Importantly, we have demonstrated that when MVL is performed in obese, insulin-resistant baboons, insulin resistance is reversed, and significant weight loss occurs. Therefore, trials performing MVL in humans with abdominal obesity and related metabolic sequelae should be explored as a potential clinical tool to ameliorate insulin resistance and treat type 2 diabetes.

Endophilin A2: A Potential Link to Adiposity and Beyond.

Adipose tissue plays a central role in regulating dynamic crosstalk between tissues and organs. A detailed description of molecules that are differentially expressed upon changes in adipose tissue mass is expected to increase our understanding of the molecular mechanisms that underlie obesity and related metabolic co-morbidities. Our previous studies suggest a possible link between endophilins (SH3Grb2 proteins) and changes in body weight. To explore this further, we sought to assess the distribution of endophilin A2 (EA2) in human adipose tissue and experimental animals. Human paired adipose tissue samples (subcutaneous and visceral) were collected from subjects undergoing elective abdominal surgery and abdominal liposuction. We observed elevated EA2 gene expression in the subcutaneous compared to that in the visceral human adipose tissue. EA2 gene expression negatively correlated with adiponectin and chemerin in visceral adipose tissue, and positively correlated with TNF-α in subcutaneous adipose tissue. EA2 gene expression was significantly downregulated during differentiation of preadipocytes in vitro. In conclusion, this study provides a description of EA2 distribution and emphasizes a need to study the roles of this protein during the progression of obesity.