Alteration in the gut microbiome is associated with changes in bone metabolism after laparoscopic sleeve gastrectomy

Laparoscopic sleeve gastrectomy (LSG), the most common bariatric surgical procedure, leads to durable weight loss and improves obesity-related comorbidities. However, it induces abnormalities in bone metabolism. One unexplored potential contributor is the gut microbiome, which influences bone metabolism and is altered after surgery. We characterized the relationship between the gut microbiome and skeletal health in severe obesity and after LSG. In a prospective cohort study, 23 adults with severe obesity underwent skeletal health assessment and stool collection preoperatively and 6 mo after LSG. Gut microbial diversity and composition were characterized using 16S rRNA gene sequencing, and fecal concentrations of short-chain fatty acids (SCFA) were measured with LC-MS/MS. Spearman's correlations and PERMANOVA analyses were applied to assess relationships between the gut microbiome and bone health measures including serum bone turnover markers (C-terminal telopeptide of type 1 collagen [CTx] and procollagen type 1 N-terminal propeptide [P1NP]), areal BMD, intestinal calcium absorption, and calciotropic hormones. Six months after LSG, CTx and P1NP increased (by median 188% and 61%, P < .01) and femoral neck BMD decreased (mean -3.3%, P < .01). Concurrently, there was a decrease in relative abundance of the phylum Firmicutes. Although there were no change in overall microbial diversity or fecal SCFA concentrations after LSG, those with greater within-subject change in gut community microbial composition (β-diversity) postoperatively had greater increases in P1NP level (ρ = 0.48, P = .02) and greater bone loss at the femoral neck (ρ = -0.43, P = .04). In addition, within-participant shifts in microbial richness/evenness (α-diversity) were associated with changes in IGF-1 levels (ρ = 0.56, P < .01). The lower the postoperative fecal butyrate concentration, the lower the IGF-1 level (ρ = 0.43, P = .04). Meanwhile, the larger the decrease in butyrate concentration, the higher the postoperative CTx (ρ = -0.43, P = .04). These findings suggest that LSG-induced gut microbiome alteration may influence skeletal outcomes postoperatively, and microbial influences on butyrate formation and IGF-1 are possible mechanisms.

A Multi-Modal Approach to Islet and Pancreas Transplantation With Calcineurin-Sparing Immunosuppression Maintains Long-Term Insulin Independence in Patients With Type I Diabetes

Long-term success in beta-cell replacement remains limited by the toxic effects of calcineurin inhibitors (CNI) on beta-cells and renal function. We report a multi-modal approach including islet and pancreas-after-islet (PAI) transplant utilizing calcineurin-sparing immunosuppression. Ten consecutive non-uremic patients with Type 1 diabetes underwent islet transplant with immunosuppression based on belatacept (BELA; n = 5) or efalizumab (EFA; n = 5). Following islet failure, patients were considered for repeat islet infusion and/or PAI transplant. 70% of patients (four EFA, three BELA) maintained insulin independence at 10 years post-islet transplant, including four patients receiving a single islet infusion and three patients undergoing PAI transplant. 60% remain insulin independent at mean follow-up of 13.3 ± 1.1 years, including one patient 9 years after discontinuing all immunosuppression for adverse events, suggesting operational tolerance. All patients who underwent repeat islet transplant experienced graft failure. Overall, patients demonstrated preserved renal function, with a mild decrease in GFR from 76.5 ± 23.1 mL/min to 50.2 ± 27.1 mL/min (p = 0.192). Patients undergoing PAI showed the greatest degree of renal impairment following initiation of CNI (56% ± 18.7% decrease in GFR). In our series, repeat islet transplant is ineffective at maintaining long-term insulin independence. PAI results in durable insulin independence but is associated with impaired renal function secondary to CNI dependence.

Intestinal Calcium Absorption Decreases After Laparoscopic Sleeve Gastrectomy Despite Optimization of Vitamin D Status

CONTEXT

Laparoscopic sleeve gastrectomy (LSG), now the most commonly performed bariatric operation, is a highly effective treatment for obesity. While Roux-en-Y gastric bypass is known to impair intestinal fractional calcium absorption (FCA) and negatively affect bone metabolism, LSG's effects on calcium homeostasis and bone health have not been well characterized.

OBJECTIVE

We determined the effect of LSG on FCA, while maintaining robust 25-hydroxyvitamin D (25OHD) levels and recommended calcium intake.

DESIGN, SETTING, PARTICIPANTS

Prospective pre-post observational cohort study of 35 women and men with severe obesity undergoing LSG.

MAIN OUTCOMES

FCA was measured preoperatively and 6 months postoperatively with a gold-standard dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and bone mineral density (BMD) by dual-energy X-ray absorptiometry and quantitative computed tomography.

RESULTS

Mean ± SD FCA decreased from 31.4 ± 15.4% preoperatively to 16.1 ± 12.3% postoperatively (P < 0.01), while median (interquartile range) 25OHD levels were 39 (32-46) ng/mL and 36 (30-46) ng/mL, respectively. Concurrently, median 1,25-dihydroxyvitamin D level increased from 60 (50-82) pg/mL to 86 (72-107) pg/mL (P < 0.01), without significant changes in parathyroid hormone or 24-hour urinary calcium levels. Bone turnover marker levels increased substantially, and areal BMD decreased at the proximal femur. Those with lower postoperative FCA had greater areal BMD loss at the total hip (ρ = 0.45, P < 0.01).

CONCLUSIONS

FCA decreases after LSG, with a concurrent rise in bone turnover marker levels and decline in BMD, despite robust 25OHD levels and with recommended calcium intake. Decline in FCA could contribute to negative skeletal effects following LSG.

Prebiotic to Improve Calcium Absorption in Postmenopausal Women After Gastric Bypass: A Randomized Controlled Trial

CONTEXT

The adverse skeletal effects of Roux-en-Y gastric bypass (RYGB) are partly caused by intestinal calcium absorption decline. Prebiotics, such as soluble corn fiber (SCF), augment colonic calcium absorption in healthy individuals.

OBJECTIVE

We tested the effects of SCF on fractional calcium absorption (FCA), biochemical parameters, and the fecal microbiome in a post-RYGB population.

METHODS

Randomized, double-blind, placebo-controlled trial of 20 postmenopausal women with history of RYGB a mean 5 years prior; a 2-month course of 20 g/day SCF or maltodextrin placebo was taken orally. The main outcome measure was between-group difference in absolute change in FCA (primary outcome) and was measured with a gold standard dual stable isotope method. Other measures included tolerability, adherence, serum calciotropic hormones and bone turnover markers, and fecal microbial composition via 16S rRNA gene sequencing.

RESULTS

Mean FCA ± SD at baseline was low at 5.5 ± 5.1%. Comparing SCF to placebo, there was no between-group difference in mean (95% CI) change in FCA (+3.4 [-6.7, +13.6]%), nor in calciotropic hormones or bone turnover markers. The SCF group had a wider variation in FCA change than placebo (SD 13.4% vs 7.0%). Those with greater change in microbial composition following SCF treatment had greater increase in FCA (r2 = 0.72, P = 0.05). SCF adherence was high, and gastrointestinal symptoms were similar between groups.

CONCLUSION

No between-group differences were observed in changes in FCA or calciotropic hormones, but wide CIs suggest a variable impact of SCF that may be due to the degree of gut microbiome alteration. Daily SCF consumption was well tolerated. Larger and longer-term studies are warranted.

Advantages and Limitations of Clinical Scores for Donation After Circulatory Death Liver Transplantation

Background: Scoring systems have been proposed to select donation after circulatory death (DCD) donors and recipients for liver transplantation (LT). We hypothesized that complex scoring systems derived in large datasets might not predict outcomes locally. Methods: Based on 1-year DCD-LT graft survival predictors in multivariate logistic regression models, we designed, validated, and compared a simple index using the University of California, San Francisco (UCSF) cohort (n = 136) and a universal-comprehensive (UC)-DCD score using the United Network for Organ Sharing (UNOS) cohort (n = 5,792) to previously published DCD scoring systems. Results: The total warm ischemia time (WIT)-index included donor WIT (dWIT) and hepatectomy time (dHep). The UC-DCD score included dWIT, dHep, recipient on mechanical ventilation, transjugular-intrahepatic-portosystemic-shunt, cause of liver disease, model for end-stage liver disease, body mass index, donor/recipient age, and cold ischemia time. In the UNOS cohort, the UC-score outperformed all previously published scores in predicting DCD-LT graft survival (AUC: 0.635 vs. ≤0.562). In the UCSF cohort, the total WIT index successfully stratified survival and biliary complications, whereas other scores did not. Conclusion: DCD risk scores generated in large cohorts provide general guidance for safe recipient/donor selection, but they must be tailored based on non-/partially-modifiable local circumstances to expand DCD utilization.

Sleeve gastrectomy prior to liver transplantation is superior to medical weight loss in reducing posttransplant metabolic complications

Strategies to optimize the management of obesity-related metabolic complications after liver transplantation (LT) are needed. We examined the effect of pre-LT sleeve gastrectomy (SG), as compared to medical weight loss (MWL), on post-LT outcomes. This is a cohort study of adults (≥18 years) with medically complicated obesity who were eligible for pre-LT SG and underwent LT from January 1, 2006 to June 1, 2016. Logistic regression models evaluated the association of SG on post-LT diabetes and hypertension, defined as new-onset or progressive disease post-LT. Cox regression models evaluated the association of SG on recurrent and de novo nonalcoholic fatty liver disease (NAFLD). Among 70 LT recipients who were eligible for pre-LT SG, 14 (20%) underwent SG and 56 (80%) underwent MWL only. Mean follow-up was 5.2 years post-LT. The SG cohort sustained higher % total body weight loss at 3 years post-LT (28.9% vs. 5.4%, p < .001). In multivariable analyses, SG was associated with significantly lower risk of post-LT diabetes (OR 0.04, 95% CI 0.00-0.41, p = .01), hypertension (OR 0.15, 95% CI 0.04-0.67, p = .01), and recurrent and de novo NAFLD (HR 0.19, 95% CI 0.04-0.91, p = .04). When compared to MWL, SG resulted in sustained weight loss and significantly lower risk of diabetes, hypertension, and recurrent and de novo NAFLD post-LT.

Arguments against the Requirement of a Biological License Application for Human Pancreatic Islets: The Position Statement of the Islets for US Collaborative Presented during the FDA Advisory Committee Meeting

The Food and Drug Administration (FDA) has been regulating human islets for allotransplantation as a biologic drug in the US. Consequently, the requirement of a biological license application (BLA) approval before clinical use of islet transplantation as a standard of care procedure has stalled the development of the field for the last 20 years. Herein, we provide our commentary to the multiple FDA’s position papers and guidance for industry arguing that BLA requirement has been inappropriately applied to allogeneic islets, which was delivered to the FDA Cellular, Tissue and Gene Therapies Advisory Committee on 15 April 2021. We provided evidence that BLA requirement and drug related regulations are inadequate in reassuring islet product quality and potency as well as patient safety and clinical outcomes. As leaders in the field of transplantation and endocrinology under the “Islets for US Collaborative” designation, we examined the current regulatory status of islet transplantation in the US and identified several anticipated negative consequences of the BLA approval. In our commentary we also offer an alternative pathway for islet transplantation under the regulatory framework for organ transplantation, which would address deficiencies of in current system.

Phase 3 trial of human islet-after-kidney transplantation in type 1 diabetes

Allogeneic islet transplant offers a minimally invasive option for β cell replacement in the treatment of type 1 diabetes (T1D). The CIT consortium trial of purified human pancreatic islets (PHPI) in patients with T1D after kidney transplant (CIT06), a National Institutes of Health-sponsored phase 3, prospective, open-label, single-arm pivotal trial of PHPI, was conducted in 24 patients with impaired awareness of hypoglycemia while receiving intensive insulin therapy. PHPI were manufactured using standardized processes. PHPI transplantation was effective with 62.5% of patients achieving the primary endpoint of freedom from severe hypoglycemic events and HbA_1c  ≤ 6.5% or reduced by ≥ 1 percentage point at 1 year posttransplant. Median HbA_1c declined from 8.1% before to 6.0% at 1 year and 6.3% at 2 and 3 years following transplant (P < .001 for all vs baseline), with related improvements in hypoglycemia awareness and glucose variability. The improved metabolic control was associated with better health-related and diabetes-related quality of life. The procedure was safe and kidney allograft function remained stable after 3 years. These results add to evidence establishing allogeneic islet transplant as a safe and effective treatment for patients with T1D and unstable glucose control despite intensive insulin treatment, supporting the indication for PHPI in the post-renal transplant setting.

Islets Transplantation at a Crossroads - Need for Urgent Regulatory Update in the United States: Perspective Presented During the Scientific Sessions 2021 at the American Diabetes Association Congress

Clinical islet allotransplantation has been successfully regulated as tissue/organ for transplantation in number of countries and is recognized as a safe and efficacious therapy for selected patients with type 1 diabetes mellitus. However, in the United States, the FDA considers pancreatic islets as a biologic drug, and islet transplantation has not yet shifted from the experimental to the clinical arena for last 20 years. In order to transplant islets, the FDA requires a valid Biological License Application (BLA) in place. The BLA process is costly and lengthy. However, despite the application of drug manufacturing technology and regulations, the final islet product sterility and potency cannot be confirmed, even when islets meet all the predetermined release criteria. Therefore, further regulation of islets as drugs is obsolete and will continue to hinder clinical application of islet transplantation in the US. The Organ Procurement and Transplantation Network together with the United Network for Organ Sharing have developed separately from the FDA and BLA regulatory framework for human organs under the Human Resources & Services Administration to assure safety and efficacy of transplantation. Based on similar biologic characteristics of islets and human organs, we propose inclusion of islets into the existing regulatory framework for organs for transplantation, along with continued FDA oversight for islet processing, as it is for other cell/tissue products exempt from BLA. This approach would reassure islet quality, efficacy and access for Americans with diabetes to this effective procedure.

Long-term follow-up of beta cell replacement therapy in 10 HIV-infected patients with renal failure secondary to type 1 diabetes mellitus

The approach to transplantation in human immunodeficiency virus (HIV)-positive patients has been conservative due to fear of exacerbating an immunocompromised condition. As a result, HIV-positive patients with diabetes were initially excluded from beta cell replacement therapy. Early reports of pancreas transplant in patients with HIV described high rates of early graft loss with limited follow-up. We report long-term follow-up of islet or pancreas transplantation in HIV-positive type 1 diabetic patients who received a kidney transplant concurrently or had previously undergone kidney transplantation. Although 4 patients developed polyoma viremia, highly active antiretroviral therapy and adequate infectious prophylaxis were successful in providing protection until CD4+ counts recovered. Coordination with HIV providers is critical to reduce the risk of rejection by minimizing drug-drug interactions. Also, protocols for prophylaxis of opportunistic infections and strategies for monitoring and treating BK viremia are important given the degree of immunosuppression required. This series demonstrates that type 1 diabetic patients with well-controlled HIV and renal failure can be appropriate candidates for beta cell replacement, with a low rate of infectious complications, early graft loss, and rejection, so excellent long-term graft survival is possible. Additionally, patients with HIV and cardiovascular contraindications can undergo islet infusion.

Increases in PYY and uncoupling of bone turnover are associated with loss of bone mass after gastric bypass surgery

CONTEXT

The gut hormones peptide YY (PYY) and ghrelin mediate in part the metabolic benefits of Roux-en-Y gastric bypass (RYGB) surgery. However, preclinical data suggest these hormones also affect the skeleton and could contribute to postoperative bone loss.

OBJECTIVE

We investigated whether changes in fasting serum total PYY and ghrelin were associated with bone turnover marker levels and loss of bone mineral density (BMD) after RYGB.

DESIGN, SETTING, PARTICIPANTS

Prospective cohort of adults undergoing RYGB (n=44) at San Francisco academic hospitals.

MAIN OUTCOME MEASURES

We analyzed 6-month changes in PYY, ghrelin, bone turnover markers, and BMD by dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). We calculated the uncoupling index (UI), reflecting the relative balance of bone resorption and formation.

RESULTS

Postoperatively, there was a trend for an increase in PYY (+25pg/mL, p=0.07) and a significant increase in ghrelin (+192pg/mL, p<0.01). PYY changes negatively correlated with changes in spine BMD by QCT (r=-0.36, p=0.02) and bone formation marker P1NP (r=-0.30, p=0.05). Relationships were significant after adjustments for age, sex, and weight loss. No consistent relationships were found between ghrelin and skeletal outcomes. Mean 6-month UI was -3.3; UI correlated with spine BMD loss by QCT (r=0.40, p=0.01).

CONCLUSIONS

Postoperative PYY increases were associated with attenuated increases in P1NP and greater declines in spine BMD by QCT. Uncoupling of bone turnover correlated with BMD loss. These findings suggest a role for PYY in loss of bone mass after RYGB and highlight the relationship between intestinal and skeletal metabolism.

A Study on the Effect of Patient Characteristics, Geographical Utilization, and Patient Outcomes for Total Pancreatectomy Alone and Total Pancreatectomy With Islet Autotransplantation in Patients With Pancreatitis in the United States

OBJECTIVES

A selective therapy for pancreatitis is total pancreatectomy and islet autotransplantation. Outcomes and geographical variability of patients who had total pancreatectomy (TP) alone or total pancreatectomy with islet autotransplantation (TPIAT) were assessed.

METHODS

Data were obtained from the Healthcare Cost and Utilization Project National Inpatient Sample database. Weighed univariate and multivariate analyses were performed to determine the effect of measured variables on outcomes.

RESULTS

Between 2002 and 2013, there were 1006 TP and 825 TPIAT in patients with a diagnosis of chronic pancreatitis, and 1705 TP and 830 TPIAT for any diagnosis of pancreatitis. The majority of the TP and TPIAT were performed in larger urban hospitals. Costs were similar for TP and TPIAT for chronic pancreatitis but were lower for TPIAT compared with TP for any type of pancreatitis. The trend for TP and TPIAT was significant in all geographical areas during the study period.

CONCLUSIONS

There is an increasing trend of both TP and TPIAT. Certain groups are more likely to be offered TPIAT compared with TP alone. More data are needed to understand disparities and barriers to TPIAT, and long-term outcomes of TPIAT such as pain control and glucose intolerance need further study.

Outcomes of Sleeve Gastrectomy in Obese Liver Transplant Candidates

Morbid obesity (body mass index [BMI] ≥40 kg/m² ) is a relative contraindication to liver transplantation (LT) at many transplant centers. The safety and efficacy of pre-LT bariatric surgery in morbidly obese LT candidates is unknown. Herein, we describe a cohort study of morbidly obese LT candidates who failed to achieve adequate weight loss through a medically supervised weight loss program and subsequently underwent sleeve gastrectomy (SG) at our institution. In total, 32 LT candidates with a median Model for End-Stage Liver Disease (MELD) score of 12 (interquartile range [IQR], 10-13) underwent SG. All LT candidates had a history of hepatic decompensation, but complications of liver disease were required to be well controlled at the time of SG. Median pre-SG BMI was 45.0 kg/m² (IQR, 42.1-49.0 kg/m² ). There were no perioperative deaths or liver-related morbidity. One patient experienced major perioperative morbidity secondary to a gastric leak, which was managed nonoperatively. Median weight loss at 6 and 12 months after SG was 22.0 kg (IQR, 18.9-26.8 kg) and 31.0 kg (IQR, 23.6-50.3 kg), respectively, corresponding to a percentage of excess body weight lost of 33.4% and 52.4%. Within 6 months after SG, 28 (88%) candidates were deemed eligible for LT. Our center's experience highlights the potential option of SG in morbidly obese LT candidates with advanced liver disease who might otherwise be excluded from pursuing LT.

Changes in Lean Mass, Absolute and Relative Muscle Strength, and Physical Performance After Gastric Bypass Surgery

CONTEXT

Bariatric surgery results in reduced muscle mass as weight is lost, but postoperative changes in muscle strength and performance are incompletely understood.

OBJECTIVE

To examine changes in body composition, strength, physical activity, and physical performance following Roux-en-Y gastric bypass (RYGB).

DESIGN, PARTICIPANTS, OUTCOMES

In a prospective cohort of 47 adults (37 women, 10 men) aged 45 ± 12 years (mean ± SD) with body mass index (BMI) 44 ± 8 kg/m2, we measured body composition by dual-energy X-ray absorptiometry, handgrip strength, physical activity, and physical performance (chair stand time, gait speed, 400-m walk time) before and 6 and 12 months after RYGB. Relative strength was calculated as absolute handgrip strength/BMI and as absolute strength/appendicular lean mass (ALM).

RESULTS

Participants experienced substantial 12-month decreases in weight (-37 ± 10 kg or 30% ± 7%), fat mass (-48% ± 12%), and total lean mass (-13% ± 6%). Mean absolute strength declined by 9% ± 17% (P < 0.01). In contrast, relative strength increased by 32% ± 25% (strength/BMI) and 9% ± 20% (strength/ALM) (P < 0.01 for both). There were clinically significant postoperative improvements in all physical performance measures, including mean improvement in gait speed of >0.1 m/s (P < 0.01) and decrease in 400-m walk time of nearly a full minute.

CONCLUSIONS

In the setting of dramatic weight loss, lean mass and absolute grip strength declined after RYGB. However, relative muscle strength and physical function improved meaningfully and are thus noteworthy positive outcomes of gastric bypass.

Oxygen Perfusion (Persufflation) of Human Pancreata Enhances Insulin Secretion and Attenuates Islet Proinflammatory Signaling

BACKGROUND

All human islets used in research and for the clinical treatment of diabetes are subject to ischemic damage during pancreas procurement, preservation, and islet isolation. A major factor influencing islet function is exposure of pancreata to cold ischemia during unavoidable windows of preservation by static cold storage (SCS). Improved preservation methods may prevent this functional deterioration. In the present study, we investigated whether pancreas preservation by gaseous oxygen perfusion (persufflation) better preserved islet function versus SCS.

METHODS

Human pancreata were preserved by SCS or by persufflation in combination with SCS. Islets were subsequently isolated, and preparations in each group matched for SCS or total preservation time were compared using dynamic glucose-stimulated insulin secretion as a measure of β-cell function and RNA sequencing to elucidate transcriptomic changes.

RESULTS

Persufflated pancreata had reduced SCS time, which resulted in islets with higher glucose-stimulated insulin secretion compared to islets from SCS only pancreata. RNA sequencing of islets from persufflated pancreata identified reduced inflammatory and greater metabolic gene expression, consistent with expectations of reducing cold ischemic exposure. Portions of these transcriptional responses were not associated with time spent in SCS and were attributable to pancreatic reoxygenation. Furthermore, persufflation extended the total preservation time by 50% without any detectable decline in islet function or viability.

CONCLUSIONS

These data demonstrate that pancreas preservation by persufflation rather than SCS before islet isolation reduces inflammatory responses and promotes metabolic pathways in human islets, which results in improved β cell function.

Effects of Gastric Bypass Surgery on Bone Mass and Microarchitecture Occur Early and Particularly Impact Postmenopausal Women

Roux-en-Y gastric bypass (RYGB) surgery is a highly effective treatment for obesity but negatively affects the skeleton. Studies of skeletal effects have generally examined areal bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), but DXA may be inaccurate in the setting of marked weight loss. Further, as a result of modestly sized samples of mostly premenopausal women and very few men, effects of RYGB by sex and menopausal status are unknown. We prospectively studied the effects of RYGB on skeletal health, including axial and appendicular volumetric BMD and appendicular bone microarchitecture and estimated strength. Obese adults (N = 48; 27 premenopausal and 11 postmenopausal women, 10 men) with mean ± SD body mass index (BMI) 44 ± 7 kg/m² were assessed before and 6 and 12 months after RYGB. Participants underwent spine and hip DXA, spine QCT, radius and tibia HR-pQCT, and laboratory evaluation. Mean 12-month weight loss was 37 kg (30% of preoperative weight). Overall median 12-month increase in serum collagen type I C-telopeptide (CTx) was 278% (p < 0.0001), with greater increases in postmenopausal than premenopausal women (p = 0.049). Femoral neck BMD by DXA decreased by mean 5.0% and 8.0% over 6 and 12 months (p < 0.0001). Spinal BMD by QCT decreased by mean 6.6% and 8.1% (p < 0.0001); declines were larger among postmenopausal than premenopausal women (11.6% versus 6.0% at 12 months, p = 0.02). Radial and tibial BMD and estimated strength by HR-pQCT declined. At the tibia, detrimental changes in trabecular microarchitecture were apparent at 6 and 12 months. Cortical porosity increased at the radius and tibia, with more dramatic 12-month increases among postmenopausal than premenopausal women or men at the tibia (51.4% versus 18.3% versus 3.0%, p < 0.01 between groups). In conclusion, detrimental effects of RYGB on axial and appendicular bone mass and microarchitecture are detectable as early as 6 months postoperatively. Postmenopausal women are at highest risk for skeletal consequences and may warrant targeted screening or interventions. © 2017 American Society for Bone and Mineral Research.

Bone Marrow Fat Changes After Gastric Bypass Surgery Are Associated With Loss of Bone Mass

Bone marrow fat is a unique fat depot that may regulate bone metabolism. Marrow fat is increased in states of low bone mass, severe underweight, and diabetes. However, longitudinal effects of weight loss and improved glucose homeostasis on marrow fat are unclear, as is the relationship between marrow fat and bone mineral density (BMD) changes. We hypothesized that after Roux-en-Y gastric bypass (RYGB) surgery, marrow fat changes are associated with BMD loss. We enrolled 30 obese women, stratified by diabetes status. Before and 6 months after RYGB, we measured BMD by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and vertebral marrow fat content by magnetic resonance spectroscopy. At baseline, those with higher marrow fat had lower BMD. Postoperatively, total body fat declined dramatically in all participants. Effects of RYGB on marrow fat differed by diabetes status (p = 0.03). Nondiabetic women showed no significant mean change in marrow fat (+1.8%, 95% confidence interval [CI] -1.8% to +5.4%, p = 0.29), although those who lost more total body fat were more likely to have marrow fat increases (r = -0.70, p = 0.01). In contrast, diabetic women demonstrated a mean marrow fat change of -6.5% (95% CI -13.1% to 0%, p = 0.05). Overall, those with greater improvements in hemoglobin A1c had decreases in marrow fat (r = 0.50, p = 0.01). Increases in IGF-1, a potential mediator of the marrow fat-bone relationship, were associated with marrow fat declines (r = -0.40, p = 0.05). Spinal volumetric BMD decreased by 6.4% ± 5.9% (p < 0.01), and femoral neck areal BMD decreased by 4.3% ± 4.1% (p < 0.01). Marrow fat and BMD changes were negatively associated, such that those with marrow fat increases had more BMD loss at both spine (r = -0.58, p < 0.01) and femoral neck (r = -0.49, p = 0.01), independent of age and menopause. Our findings suggest that glucose metabolism and weight loss may influence marrow fat behavior, and marrow fat may be a determinant of bone metabolism. © 2017 American Society for Bone and Mineral Research.

Correction: An intravascular bioartificial pancreas device (iBAP) with silicon nanopore membranes (SNM) for islet encapsulation under convective mass transport

Correction for 'An intravascular bioartificial pancreas device (iBAP) with silicon nanopore membranes (SNM) for islet encapsulation under convective mass transport' by Shang Song et al., Lab Chip, 2017, 17, 1778-1792.

An intravascular bioartificial pancreas device (iBAP) with silicon nanopore membranes (SNM) for islet encapsulation under convective mass transport

Diffusion-based bioartificial pancreas (BAP) devices are limited by poor islet viability and functionality due to inadequate mass transfer resulting in islet hypoxia and delayed glucose-insulin kinetics. While intravascular ultrafiltration-based BAP devices possess enhanced glucose-insulin kinetics, the polymer membranes used in these devices provide inadequate ultrafiltrate flow rates and result in excessive thrombosis. Here, we report the silicon nanopore membrane (SNM), which exhibits a greater hydraulic permeability and a superior pore size selectivity compared to polymer membranes for use in BAP applications. Specifically, we demonstrate that the SNM-based intravascular BAP with ∼10 and ∼40 nm pore sized membranes support high islet viability (>60%) and functionality (<15 minute insulin response to glucose stimulation) at clinically relevant islet densities (5700 and 11 400 IE per cm²) under convection in vitro. In vivo studies with ∼10 nm pore sized SNM in a porcine model showed high islet viability (>85%) at clinically relevant islet density (5700 IE per cm²), c-peptide concentration of 144 pM in the outflow ultrafiltrate, and hemocompatibility under convection. These promising findings offer insights on the development of next generation of full-scale intravascular devices to treat T1D patients in the future.

Glucose-Stimulated Insulin Response of Silicon Nanopore-Immunoprotected Islets under Convective Transport

Major clinical challenges associated with islet transplantation for type 1 diabetes include shortage of donor organs, poor engraftment due to ischemia, and need for immunosuppressive medications. Semipermeable membrane capsules can immunoprotect transplanted islets by blocking passage of the host's immune components while providing exchange of glucose, insulin, and other small molecules. However, capsules-based diffusive transport often exacerbates ischemic injury to islets by reducing the rate of oxygen and nutrient transport. We previously reported the efficacy of a newly developed semipermeable ultrafiltration membrane, the silicon nanopore membrane (SNM) under convective-driven transport, in limiting the passage of pro-inflammatory cytokines while overcoming the mass transfer limitations associated with diffusion through nanometer-scale pores. In this study, we report that SNM-encapsulated mouse islets perfused in culture solution under convection outperformed those under diffusive conditions in terms of magnitude (1.49-fold increase in stimulation index and 3.86-fold decrease in shutdown index) and rate of insulin secretion (1.19-fold increase and 6.45-fold decrease during high and low glucose challenges), respectively. Moreover, SNM-encapsulated mouse islets under convection demonstrated rapid glucose-insulin sensing within a physiologically relevant time-scale while retaining healthy islet viability even under cytokine exposure. We conclude that encapsulation of islets with SNM under convection improves islet in vitro functionality. This approach may provide a novel strategy for islet transplantation in the clinical setting.

National Institutes of Health-Sponsored Clinical Islet Transplantation Consortium Phase 3 Trial: Manufacture of a Complex Cellular Product at Eight Processing Facilities

Eight manufacturing facilities participating in the National Institutes of Health-sponsored Clinical Islet Transplantation (CIT) Consortium jointly developed and implemented a harmonized process for the manufacture of allogeneic purified human pancreatic islet (PHPI) product evaluated in a phase 3 trial in subjects with type 1 diabetes. Manufacturing was controlled by a common master production batch record, standard operating procedures that included acceptance criteria for deceased donor organ pancreata and critical raw materials, PHPI product specifications, certificate of analysis, and test methods. The process was compliant with Current Good Manufacturing Practices and Current Good Tissue Practices. This report describes the manufacturing process for 75 PHPI clinical lots and summarizes the results, including lot release. The results demonstrate the feasibility of implementing a harmonized process at multiple facilities for the manufacture of a complex cellular product. The quality systems and regulatory and operational strategies developed by the CIT Consortium yielded product lots that met the prespecified characteristics of safety, purity, potency, and identity and were successfully transplanted into 48 subjects. No adverse events attributable to the product and no cases of primary nonfunction were observed.

Abnormalities in biomarkers of mineral and bone metabolism in kidney donors

Previous studies have suggested that kidney donors may have abnormalities of mineral and bone metabolism typically seen in chronic kidney disease. This may have important implications for the skeletal health of living kidney donors and for our understanding of the pathogenesis of long-term mineral and bone disorders in chronic kidney disease. In this prospective study, 182 of 203 kidney donors and 173 of 201 paired normal controls had markers of mineral and bone metabolism measured before and at 6 and 36 months after donation (ALTOLD Study). Donors had significantly higher serum concentrations of intact parathyroid hormone (24.6% and 19.5%) and fibroblast growth factor-23 (9.5% and 8.4%) at 6 and 36 months, respectively, as compared to healthy controls, and significantly reduced tubular phosphate reabsorption (-7.0% and -5.0%) and serum phosphate concentrations (-6.4% and -2.3%). Serum 1,25-dihydroxyvitamin D3 concentrations were significantly lower (-17.1% and -12.6%), while 25-hydroxyvitamin D (21.4% and 19.4%) concentrations were significantly higher in donors compared to controls. Moreover, significantly higher concentrations of the bone resorption markers, carboxyterminal cross-linking telopeptide of bone collagen (30.1% and 13.8%) and aminoterminal cross-linking telopeptide of bone collagen (14.2% and 13.0%), and the bone formation markers, osteocalcin (26.3% and 2.7%) and procollagen type I N-terminal propeptide (24.3% and 8.9%), were observed in donors. Thus, kidney donation alters serum markers of bone metabolism that could reflect impaired bone health. Additional long-term studies that include assessment of skeletal architecture and integrity are warranted in kidney donors.

Phase 3 Trial of Transplantation of Human Islets in Type 1 Diabetes Complicated by Severe Hypoglycemia

OBJECTIVE

Impaired awareness of hypoglycemia (IAH) and severe hypoglycemic events (SHEs) cause substantial morbidity and mortality in patients with type 1 diabetes (T1D). Current therapies are effective in preventing SHEs in 50-80% of patients with IAH and SHEs, leaving a substantial number of patients at risk. We evaluated the effectiveness and safety of a standardized human pancreatic islet product in subjects in whom IAH and SHEs persisted despite medical treatment.

RESEARCH DESIGN AND METHODS

This multicenter, single-arm, phase 3 study of the investigational product purified human pancreatic islets (PHPI) was conducted at eight centers in North America. Forty-eight adults with T1D for >5 years, absent stimulated C-peptide, and documented IAH and SHEs despite expert care were enrolled. Each received immunosuppression and one or more transplants of PHPI, manufactured on-site under good manufacturing practice conditions using a common batch record and standardized lot release criteria and test methods. The primary end point was the achievement of HbA1c <7.0% (53 mmol/mol) at day 365 and freedom from SHEs from day 28 to day 365 after the first transplant.

RESULTS

The primary end point was successfully met by 87.5% of subjects at 1 year and by 71% at 2 years. The median HbA1c level was 5.6% (38 mmol/mol) at both 1 and 2 years. Hypoglycemia awareness was restored, with highly significant improvements in Clarke and HYPO scores (P > 0.0001). No study-related deaths or disabilities occurred. Five of the enrollees (10.4%) experienced bleeds requiring transfusions (corresponding to 5 of 75 procedures), and two enrollees (4.1%) had infections attributed to immunosuppression. Glomerular filtration rate decreased significantly on immunosuppression, and donor-specific antibodies developed in two patients.

CONCLUSIONS

Transplanted PHPI provided glycemic control, restoration of hypoglycemia awareness, and protection from SHEs in subjects with intractable IAH and SHEs. Safety events occurred related to the infusion procedure and immunosuppression, including bleeding and decreased renal function. Islet transplantation should be considered for patients with T1D and IAH in whom other, less invasive current treatments have been ineffective in preventing SHEs.

Effect of Immigration Status on Outcomes in Pediatric Kidney Transplant Recipients

Kidney transplantation is the optimal treatment for children with end-stage renal disease. For children with undocumented immigration status, access to kidney transplantation is limited, and data on transplant outcomes in this population are scarce. The goal of the present retrospective single-center study was to compare outcomes after kidney transplantation in undocumented children with those of US citizen children. Undocumented residency status was identified in 48 (17%) of 289 children who received a kidney transplant between 1998 and 2010. In undocumented recipients, graft survival at 1 and 5 years posttransplantation was similar, and mean estimated glomerular filtration rate at 1 year was higher than that in recipients who were citizens. The risk of allograft failure was lower in undocumented recipients relative to that in citizens at 5 years posttransplantation, after adjustment for patient age, donor age, donor type, and HLA mismatch (p < 0.04). In contrast, nearly one in five undocumented recipients who reached 21 years of age lost their graft, primarily because they were unable to pay for immunosuppressive medications once their state-funded insurance had ended. These findings support the ongoing need for immigration policies for the undocumented that facilitate access to work-permits and employment-related insurance for this disadvantaged group.

A Multicenter Study: North American Islet Donor Score in Donor Pancreas Selection for Human Islet Isolation for Transplantation

Selection of an optimal donor pancreas is the first key task for successful islet isolation. We conducted a retrospective multicenter study in 11 centers in North America to develop an islet donor scoring system using donor variables. The data set consisting of 1,056 deceased donors was used for development of a scoring system to predict islet isolation success (defined as postpurification islet yield >400,000 islet equivalents). With the aid of univariate logistic regression analyses, we developed the North American Islet Donor Score (NAIDS) ranging from 0 to 100 points. The c index in the development cohort was 0.73 (95% confidence interval 0.70-0.76). The success rate increased proportionally as the NAIDS increased, from 6.8% success in the NAIDS < 50 points to 53.7% success in the NAIDS ≥ 80 points. We further validated the NAIDS using a separate set of data consisting of 179 islet isolations. A comparable outcome of the NAIDS was observed in the validation cohort. The NAIDS may be a useful tool for donor pancreas selection in clinical practice. Apart from its utility in clinical decision making, the NAIDS may also be used in a research setting as a standardized measurement of pancreas quality.

Expanded indications for bariatric surgery: should patients on chronic steroids be offered bariatric procedures?

BACKGROUND

Patients who take chronic corticosteroids are increasingly referred for bariatric surgery. Little is known about their clinical outcomes.

OBJECTIVE

Determine whether chronic steroid use is associated with increased morbidity and mortality after stapled bariatric procedures.

SETTING

American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database.

METHODS

All patients who underwent laparoscopic sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass and were reported to the ACS-NSQIP from 2011 to 2013 were reviewed. Patients were grouped based on type of surgery and history of chronic steroid use. Primary outcome measures were mortality and serious morbidity in the first 30 days. Regression analyses were used to determine predictors of outcome.

RESULTS

Of 23,798 patients who underwent laparoscopic sleeve gastrectomy and 38,184 who underwent Roux-en-Y gastric bypass, 385 (1.6%) and 430 (1.1%), respectively, were on chronic steroids. Patients on chronic steroids had a 3.4 times increased likelihood of dying within 30 days (95% confidence interval 1.4-8.1, P = .007), and 2-fold increased odds of serious complications (95% confidence interval 1.2-2.3, P = .008), regardless of surgery type. In multivariate regression, steroid usage remained an independent predictor of mortality and serious complications.

CONCLUSION

In a large, nationally representative patient database, steroid use independently predicted mortality and serious postoperative complications after stapled bariatric procedures. Surgeons should be cautious about offering stapled bariatric procedures to patients on chronic steroids.

Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status

Roux-en-Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2 D-mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m(2)). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6-month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24-hour urinary Ca decreased, PTH increased, and 1,25(OH)2 D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = -0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long-term skeletal consequences should be investigated.

Changes in vertebral bone marrow fat and bone mass after gastric bypass surgery: A pilot study

Bone marrow fat may serve a metabolic role distinct from other fat depots, and it may be altered by metabolic conditions including diabetes. Caloric restriction paradoxically increases marrow fat in mice, and women with anorexia nervosa have high marrow fat. The longitudinal effect of weight loss on marrow fat in humans is unknown. We hypothesized that marrow fat increases after Roux-en-Y gastric bypass (RYGB) surgery, as total body fat decreases. In a pilot study of 11 morbidly obese women (6 diabetic, 5 nondiabetic), we measured vertebral marrow fat content (percentage fat fraction) before and 6 months after RYGB using magnetic resonance spectroscopy. Total body fat mass declined in all participants (mean ± SD decline 19.1 ± 6.1 kg or 36.5% ± 10.9%, p<0.001). Areal bone mineral density (BMD) decreased by 5.2% ± 3.5% and 4.1% ± 2.6% at the femoral neck and total hip, respectively, and volumetric BMD decreased at the spine by 7.4% ± 2.8% (p<0.001 for all). Effects of RYGB on marrow fat differed by diabetes status (adjusted p=0.04). There was little mean change in marrow fat in nondiabetic women (mean +0.9%, 95% CI -10.0 to +11.7%, p=0.84). In contrast, marrow fat decreased in diabetic women (-7.5%, 95% CI -15.2 to +0.1%, p=0.05). Changes in total body fat mass and marrow fat were inversely correlated among nondiabetic (r=-0.96, p=0.01) but not diabetic (r=0.52, p=0.29) participants. In conclusion, among those without diabetes, marrow fat is maintained on average after RYGB, despite dramatic declines in overall fat mass. Among those with diabetes, RYGB may reduce marrow fat. Thus, future studies of marrow fat should take diabetes status into account. Marrow fat may have unique metabolic behavior compared with other fat depots.

Human islet viability and function is maintained during high-density shipment in silicone rubber membrane vessels

BACKGROUND

The shipment of human islets (IE) from processing centers to distant laboratories is beneficial for both research and clinical applications. The maintenance of islet viability and function in transit is critically important. Gas-permeable silicone rubber membrane (SRM) vessels reduce the risk of hypoxia-induced death or dysfunction during high-density islet culture or shipment. SRM vessels may offer additional advantages: they are cost-effective (fewer flasks, less labor needed), safer (lower contamination risk), and simpler (culture vessel can also be used for shipment).

METHOD

IE were isolated from two manufacturing centers and shipped in 10-cm(2) surface area SRM vessels in temperature- and pressure-controlled containers to a distant center after at least 2 days of culture (n = 6). Three conditions were examined: low density (LD), high density (HD), and a microcentrifuge tube negative control (NC). LD was designed to mimic the standard culture density for IE preparations (200 IE/cm(2)), while HD was designed to have a 20-fold higher tissue density, which would enable the culture of an entire human isolation in 1-3 vessels. Upon receipt, islets were assessed for viability (measured by oxygen consumption rate normalized to DNA content [OCR/DNA)]), quantity (measured by DNA), and, when possible, potency and function (measured by dynamic glucose-stimulated insulin secretion measurements and transplants in immunodeficient B6 Rag(+/-) mice). Postshipment OCR/DNA was not reduced in HD vs LD and was substantially reduced in the NC condition. HD islets exhibited normal function postshipment. Based on the data, we conclude that entire islet isolations (up to 400,000 IE) may be shipped using a single, larger SRM vessel with no negative effect on viability and ex vivo and in vivo function.

Laparoscopic sleeve gastrectomy is safe and efficacious for pretransplant candidates

BACKGROUND

Morbid obesity is a relative contraindication for organ transplant because it is associated with higher postoperative morbidity and mortality. The safety and efficacy of laparoscopic sleeve gastrectomy (LSG) as a weight loss method for patients awaiting transplant has not been examined.

METHODS

A retrospective review was performed on morbidly obese patients awaiting liver or kidney transplant who underwent LSG from 2006 to 2012. Data included patient demographic characteristics, operative details, 30-day complications, percentage of excess weight loss, postoperative laboratory data, and status of transplant candidacy.

RESULTS

Twenty-six pretransplant patients underwent LSG. The mean age was 57 years, and 17 (65%) were women. Six patients had end-stage renal disease, and 20 patients had end-stage liver disease. The preoperative mean body mass index was 48.3 kg/m(2) (range 38-60.4 kg/m(2)). There were no deaths, and there were 6 postoperative complications: 2 superficial wound infections, 1 staple line leak, 1 postoperative bleed requiring blood transfusion, 1 transient encephalopathy, and 1 temporary renal insufficiency. The mean percentage of excess weight loss at 1, 3, and 12 months was 17% (n = 24/26), 26% (n = 23/26), and 50% (n = 18/20), respectively. All patients met our institution's body mass index cutoffs for transplantation by 12 months after the procedure. One patient's renal function stabilized, and he was taken off the transplant list. Eight patients eventually underwent solid organ transplant. Six received liver transplants, 1 patient received a combined liver and kidney transplant, and 1 received a kidney transplant. The mean time between LSG and transplant was 16.6 months.

CONCLUSIONS

This is the largest case series involving LSG in patients awaiting solid organ transplantation. LSG is well tolerated, is technically feasible, and improves candidacy for transplantation.

Experience with laparoscopic donor nephrectomy among more than 1000 cases: low complication rates, despite more challenging cases

HYPOTHESIS

Despite the overall acceptance of laparoscopic donor nephrectomy (LDNX), concern remains about the application of this technique in certain complex situations, such as right-sided nephrectomies and in donors with complex kidney anatomy and obese donors. This study was designed to determine if complication rates have remained stable as we have offered LDNX to all medically acceptable donors and to analyze the results of cases in each of the complex categories. We hypothesized that complication rates in the 3 complex categories would be equivalent to those among more straightforward cases.

DESIGN

Retrospective medical record review.

SETTING

Academic medical center.

PATIENTS

A total of 1045 patients who underwent LDNX between November 3, 1999, and August 28, 2009.

MAIN OUTCOMES MEASURES

Operative times, lengths of hospital stay, overall complications, major complications, conversions to open surgery, blood transfusions, readmissions, and reoperations.

RESULTS

The outcomes of the first 250 patients (when LDNX was selectively offered) were compared with the outcomes of the last 795 patients (when LDNX was offered to all medically acceptable donors). Overall operative times significantly improved (212 vs 176 minutes), overall complication rates did not change (6.4% vs 5.5%), and major complication rates significantly declined (4.0% vs 1.4%). Among the last 795 patients, 1 conversion to open surgery and 1 blood transfusion occurred. There were no deaths in the series. Moreover, no differences in overall or major complication rates were seen when cases involving 200 right-sided nephrectomies, 204 donors with complex kidney anatomy, and 148 obese donors were analyzed independently.

CONCLUSIONS

Low complication rates persist for LDNX, even when applied to more technically challenging cases. This procedure is offered to all medically acceptable donors, with an excellent safety profile, and should be considered the standard of care for kidney donation.

Islet transplantation in type 1 diabetics using an immunosuppressive protocol based on the anti-LFA-1 antibody efalizumab

The applicability of islet transplantation as treatment for type 1 diabetes is limited by renal and islet toxicities of currently available immunosuppressants. We describe a novel immunosuppressive regimen using the antileukocyte functional antigen-1 antibody efalizumab which permits long-term islet allograft survival while reducing the need for corticosteroids and calcineurin inhibitors (CNI). Eight patients with type 1 diabetes and hypoglycemic unawareness received intraportal allogeneic islet transplants. Immunosuppression consisted of antithymocyte globulin induction followed by maintenance with efalizumab and sirolimus or mycophenolate. When efalizumab was withdrawn from the market in mid 2009, all patients were transitioned to regimens consisting of mycophenolate and sirolimus or mycophenolate and tacrolimus. All patients achieved insulin independence and four out of eight patients became independent after single-islet transplants. Insulin independent patients had no further hypoglycemic events, hemoglobin A1c levels decreased and renal function remained stable. Efalizumab was well tolerated and no serious adverse events were encountered. Although long-term follow-up is limited by discontinuation of efalizumab and transition to conventional imunnosuppression (including CNI in four cases), these results demonstrate that insulin independence after islet transplantation can be achieved with a CNI and steroid-free regimen. Such an approach may minimize renal and islet toxicity and thus further improve long-term islet allograft survival.

Clinical islet transplantation at the University of California, San Francisco

The UCSF clinical islet transplant program has evolved to utilize immunosuppressive strategies that do not rely on CNIs or other nephro- and beta-cell-toxic immunosuppressive agents. These novel strategies depend on lymphocyte-depleting induction immunotherapy and maintenance immunosuppression with novel agents that focus on co-stimulation and/or lymphocyte migration blockade. These drugs are well tolerated, frequently allow establishment of insulin independence after single islet infusions, and minimize allosensitization. Our early results suggest these regimens will be attractive immunosuppressive agents for future protocols in allogeneic islet transplantation as well as protocols utilizing stem-cell-derived beta cells.

Portomesenteric venous thrombosis after laparoscopic surgery: a systematic literature review

BACKGROUND

Portomesenteric venous thrombosis (PVT) is an uncommon but potentially lethal condition reported after several laparoscopic procedures. Its presentation, treatment, and outcomes remain poorly understood, and possible etiologic factors include venous stasis from increased intra-abdominal pressure, intraoperative manipulation, or damage to the splanchnic endothelium and systemic thrombophilic states.

DESIGN

Systematic literature review.

SETTING

Academic research.

SUBJECTS

We summarized the clinical presentation and outcomes of PVT after laparoscopic surgery other than splenectomy in 18 subjects and reviewed the treatment strategies.

MAIN OUTCOME MEASURES

Systematic review of the literature on PVT after laparoscopic procedures other than splenectomy.

RESULTS

Eighteen cases of PVT following laparoscopic procedures were identified after Roux-en-Y gastric bypass (n = 7), Nissen fundoplication (n = 5), partial colectomy (n = 3), cholecystectomy (n = 2), and appendectomy (n = 1). The mean patient age was 42 years (age range, 20-74 years). Systemic predispositions toward venous thrombosis were identified in 11 patients. Clinical symptoms consisted primarily of abdominal pain manifested, on average, 14 days (range, 3-42 days) after surgery. Thrombus location varied, but 8 patients had a combination of portal and superior mesenteric venous thrombosis. Sixteen patients were treated with anticoagulation therapy. Ten patients underwent major interventions, including exploratory laparotomy in 6 patients and thrombolytic therapy in 4 patients. Six patients had complications, and 2 patients died.

CONCLUSIONS

Portomesenteric venous thrombosis following laparoscopic surgery usually manifests as nonspecific abdominal pain. Computed tomography can readily provide the diagnosis and demonstrate the extent of the disease. Treatment should be individualized based on the extent of thrombosis and the presence of bowel ischemia but should include anticoagulation therapy. Venous stasis from increased intra-abdominal pressure, intraoperative manipulation of splanchnic vasculature, and systemic thrombophilic states likely converges to produce this potentially lethal condition.

Long-term renal function and cardiovascular disease risk in obese kidney donors

BACKGROUND AND OBJECTIVES

Increasing demand for live-donor kidneys has encouraged the use of obese donors despite the absence of long-term outcome data and evidence that obesity can adversely affect renal function. We wished to determine whether obesity increased the risk for renal dysfunction and other medical comorbidities in donors several years after donation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Ninety-eight patients who donated a kidney 5 to 40 years previously were stratified according to body mass index (BMI) at donation and evaluated for renal dysfunction and risk factors for cardiovascular disease. Patients who were from the 2005 through 2006 National Health and Nutrition Examination Survey database; did not have renal disease; and were matched for age, gender, race, and BMI served as two-kidney control subjects.

RESULTS

Renal function in obese (BMI > or =30) and nonobese (BMI <30) donors was similar, and both donor groups had reduced renal function compared with BMI-matched two-kidney control subjects. Obesity was associated with more hypertension and dyslipidemias in both donors and two-kidney control subjects; however, there were no significant differences between the two groups within each BMI category.

CONCLUSIONS

These results indicate that obese donors are not at higher risk for long-term reduced renal function compared with nonobese donors and that the increased incidence of hypertension and other cardiovascular disease risk factors in obese donors is due to their obesity and is not further exacerbated by nephrectomy. These findings support the current practice of using otherwise healthy overweight and obese donors but emphasize the need for more intensive preoperative education and postoperative health care maintenance in this donor group.

A clinical scoring system for predicting nonalcoholic steatohepatitis in morbidly obese patients

Nonalcoholic steatohepatitis (NASH) is common in morbidly obese persons. Liver biopsy is diagnostic but technically challenging in such individuals. This study was undertaken to develop a clinically useful scoring system to predict the probability of NASH in morbidly obese persons, thus assisting in the decision to perform liver biopsy. Consecutive subjects undergoing bariatric surgery without evidence of other liver disease underwent intraoperative liver biopsy. The outcome was pathologic diagnosis of NASH. Predictors evaluated were demographic, clinical, and laboratory variables. A clinical scoring system was constructed by rounding the estimated regression coefficients for the independent predictors in a multivariate logistic model for the diagnosis of NASH. Of 200 subjects studied, 64 (32%) had NASH. Median body mass index was 48 kg/m(2) (interquartile range, 43-55). Multivariate analysis identified six predictive factors for NASH: the diagnosis of hypertension (odds ratio [OR], 2.4; 95% confidence interval [CI], 1-5.6), type 2 diabetes (OR, 2.6; 95% CI, 1.1-6.3), sleep apnea (OR, 4.0; 95% CI, 1.3-12.2), AST > 27 IU/L (OR, 2.9; 95% CI, 1.2-7.0), alanine aminotransferase (ALT) > 27 IU/L (OR, 3.3; 95% CI, 1.4-8.0), and non-Black race (OR, 8.4; 95% CI, 1.9-37.1). A NASH Clinical Scoring System for Morbid Obesity was derived to predict the probability of NASH in four categories (low, intermediate, high, and very high).

CONCLUSION

The proposed clinical scoring can predict NASH in morbidly obese persons with sufficient accuracy to be considered for clinical use, identifying a very high-risk group in whom liver biopsy would be very likely to detect NASH, as well as a low-risk group in whom biopsy can be safely delayed or avoided.

Laparoscopic bariatric surgery improves candidacy in morbidly obese patients awaiting transplantation

BACKGROUND

To evaluate, at a university tertiary referral center, the safety and efficacy of laparoscopic Roux-en-Y gastric bypass (LRYGB) in patients with end-stage renal disease (ESRD) and laparoscopic sleeve gastrectomy (LSG) in patients with cirrhosis or end-stage lung disease (ESLD); and to determine whether these procedures help patients become better candidates for transplantation.

METHODS

A retrospective review was performed of selected patients with end-stage organ failure who were not eligible for transplantation because of morbid obesity who underwent LRYGB or LSG. The prospectively collected data included demographics, operative details, complications, percentage of excess weight loss, postoperative laboratory data, and status of transplant candidacy.

RESULTS

Of the 15 patients, 7 with ESRD underwent LRYGB and 6 with cirrhosis and 2 with ESLD underwent LSG. Complications developed in 2 patients (both with cirrhosis); no patient died. The mean follow-up was 12.4 months, and the mean percentage of excess weight loss at > or =9 months was 61% (ESRD), 33% (cirrhosis), and 61.5% (ESLD). Obesity-associated co-morbidities improved or resolved in all patients. Serum albumin and other nutritional parameters at > or =9 months after surgery were similar to the preoperative levels in all 3 groups. At the most recent follow-up visit, 14 (93%) of 15 patients had reached our institution's body mass index limit for transplantation and were awaiting transplantation; 1 patient with ESLD underwent successful lung transplant.

CONCLUSION

The results of this pilot study have provided preliminary evidence that LRYGB in patients with ESRD and LSG in patients with cirrhosis or ESLD is safe, well-tolerated, and improves their candidacy for transplantation.

The impact of roux limb length on weight loss after gastric bypass

BACKGROUND

Extending the length of the Roux limb (RL) in gastric bypass (GBP) may improve weight loss in super obese patients (body mass index [BMI] > 50 kg/m(2)), but no consensus exists about the optimal length of the RL. We sought to determine the impact of RL length on weight loss in super obese patients 1 year after GBP.

MATERIALS AND METHODS

One-year weight loss outcomes were analyzed in all super obese patients who underwent consecutive and primary laparoscopic or open GBP between January 2003 and June 2006. Patients were divided into two groups according to RL length (100 vs. 150 cm). The RL length was at the discretion of the attending surgeon. Baseline and follow-up data were collected prospectively. Multiple linear regression was used to adjust for potential confounders in the weight loss outcomes.

RESULTS

Twelve-month follow-up data were available in 137 (85%) of 161 patients with a BMI >or= 50 who underwent GBP during the study period. An RL of 100 or 150 cm was used in 102 (74.5%) and 35 patients (25.5%), respectively. In multivariate analysis, patients with the 150-cm RL lost more weight (68.5 vs. 55.3 kg, p < 0.01), had a greater change in BMI (25 vs. 21 kg/m(2), p = 0.01), and had greater excess weight loss (64 vs. 53%, p < 0.01).

CONCLUSION

A 150-cm RL provides better weight loss outcomes in super obese patients at 1-year follow-up.

Predictors, treatment, and outcomes of gastrojejunostomy stricture after gastric bypass for morbid obesity

BACKGROUND

The aims of this study were to determine the rate of gastrojejunostomy (GJ) stricture following Roux-en-Y gastric bypass (RYGBP), the independent predictors of stricture, and clinical outcomes with and without a stricture.

METHODS

Univariate and multivariate analysis of peri-operative and outcomes data were prospectively collected from 379 morbidly obese patients who underwent consecutive open or laparoscopic RYGBP from January 2003 to August 2006. Predictors studied were age, gender, BMI, co-morbidities, surgical technique (hand-sewn vs linear stapler vs 21-mm vs 25-mm circular stapler; open vs laparoscopic; retrocolic retrogastric vs antecolic antegastric Roux limb course, and Roux limb length), and surgeon experience. Outcomes studied consisted of occurrence of GJ strictures, technical details and outcomes after endoscopic therapy, and excess weight loss (EWL) at 12 months.

RESULTS

15 patients (4.1%) developed a GJ stricture. The use of a 21-mm circular stapler was identified as the only independent predictor of a GJ stricture (odds ratio 11.3; 95% CI 2.2-57.4, P = 0.004). Endoscopic dilation relieved stricture symptoms in all patients (60% one dilation only). There was no significant difference in %EWL at 12 months between the patients with a stricture (median EWL 54%, IQR 49-63) vs. those without a stricture (median EWL 61%, ent predictor of GJ stricture. Endoscopic dilation relieved symptoms in all patients. Weight loss is independent of the anastomotic technique used and occurrence of a GJ stricture.

Catheter-directed therapy for DVT after pancreas transplantation

INTRODUCTION

Iliac vein deep venous thrombosis (DVT) ipsilateral to the pancreas transplant can lead to severe leg edema and compromise graft function. Treatment modalities for iliac vein DVT in the pancreas transplant recipient are limited.

METHODS

Medical records of patients receiving pancreas transplants at a single center from November 1989 to July 2003 were reviewed retrospectively, identifying patients with iliac vein DVT. There were 287 pancreas transplants performed during this time. Pancreas transplantation in all recipients was performed in the right iliac fossa with the arterial supply consisting of a donor iliac artery Y interposition graft. Systemic venous drainage was to the iliac vein. Exocrine drainage was enteric or to the bladder.

RESULTS

Four (1.4%) cases of iliac DVT were identified. All patients manifested lower extremity edema ipsilateral to the pancreas transplant. DVT was detected by ultrasound on days 4, 5, 13, and 60 post-transplant. In all cases, the iliac vein caudad to the pancreatic venous anastomosis was noted to be stenotic. Management involved balloon dilatation and endovascular stent placement in one patient, thrombolysis with tissue plasma antigen (t-PA) followed by stent placement in one patient, and percutaneous mechanical thrombectomy in two patients. All patients had improvement in leg edema and two patients continue to have good pancreatic allograft function.

CONCLUSIONS

Iliac DVT is a rare complication of pancreas transplantation that usually develops in an area of stenosis caudad to the pancreatic venous anastomosis. Catheter-based treatment modalities with use of endovascular stents for treatment of underlying stenoses can serve as an adjunct in treating these complications.

Spectrum and risk factors of complications after gastric bypass

OBJECTIVE

To study the spectrum of and risk factors for complications after gastric bypass (GBP).

DESIGN

Prospective cohort study.

SETTING

Academic tertiary referral center.

PATIENTS

All morbidly obese patients who underwent open or laparoscopic GBP between January 2003 and December 2006.

MAIN OUTCOME MEASURES

Complications were stratified by grade: grade I, only bedside procedure; grade II, therapeutic intervention but without lasting disability; grade III, irreversible deficits; and grade IV, death. Data were analyzed using logistic regression to identify independent risk factors of complications after GBP. Predictors investigated were age, race, sex, marital and insurance status, body mass index, obesity-associated comorbidities, American Society of Anesthesiologists Physical Status Class, operating room time, open or laparoscopic approach, and surgeon experience.

RESULTS

Of the 404 morbidly obese patients who underwent consecutive open (n = 72) or laparoscopic (n = 332) GBP, 74 (18.3%) experienced 107 complications. Grade I and II complications were more frequent after open GBP (grade I, 19.4% after open vs 3.9% after laparoscopic operations, P < .001; grade II, 20.8% after open vs 8.4% after laparoscopic operations, P < .001), and 55% were wound related. Grades III and IV complications occurred in only 4 patients (1%), and frequency was similar for open and laparoscopic cases. Three factors were independently predictive of complications: diabetes mellitus (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.1-3.3; P = .02), early surgeon experience (OR, 2.5; 95% CI, 1.4-4.2; P = .001), and open approach (OR, 3.9; 95% CI, 2.1-7.3; P < .001).

CONCLUSIONS

Complications occurred in 18.3% of patients, but 95% were treated without leading to lasting disability. Presence of diabetes, early surgeon experience, and an open approach are risk factors of complications.

Routine upper GI series after gastric bypass does not reliably identify anastomotic leaks or predict stricture formation

BACKGROUND

Many surgeons who perform Roux-en-Y gastric bypass (RYGB) for morbid obesity routinely obtain an upper gastrointestinal (GI) series in the early postoperative period to search for anastomotic leaks and signs of stricture formation at the gastrojejunostomy. We hypothesized that this practice is unreliable.

METHODS

We analyzed 654 consecutive RYGBs, of which 63% were completed laparoscopically. An upper GI series was obtained in 634 (97%) patients. The radiographic findings (leak or delayed emptying) were compared with clinical outcomes (leak or stricture formation) to calculate the sensitivity and specificity. Univariate analysis identified risk factors for leaks or stricture formation; events were too few for multivariate analysis.

RESULTS

Of 634 routine upper GI series, anastomotic leaks at the gastrojejunostomy were diagnosed in 5 (0.8%); 2 of these 5 were later reinterpreted as artifacts. Four leaks were not seen on the initial upper GI series, yielding an overall sensitivity of 43% and a positive predictive value (PPV) of 60%. Univariate analysis showed that cases done early (odds ratio [OR] 5.4 for the first 100 cases, p = 0.02) and prolonged operating time (OR 7.8 for cases >or= 300 min, p = 0.01) were associated with leaks. Emptying into the Roux-en-Y limb was delayed in 127 (20%) of the upper GI series. Strictures requiring dilatation developed in 16 (2.4%) patients. The PPV of delayed emptying for stricture formation was 6%. Risk factors for stricture formation included stapled anastomosis (OR 7.8, p = 0.002), surgeon inexperience (OR 2.9 for first 50 cases, p = 0.04), and delayed emptying (OR 3.3; p = 0.02).

CONCLUSIONS

Because the incidence of anastomotic complications and the sensitivity of upper GI series were both low, routine upper GI series did not reliably identify leaks or predict stricture formation. A selective approach, whereby imaging is reserved for patients with clinical evidence of a leak or stricture, may be more appropriate.

Antibody-mediated rejection of a pancreas allograft

The role of antibody-mediated rejection (AMR) in pancreas transplantation is poorly understood. Here, we report on a patient who developed AMR of his pancreas allograft after receiving a simultaneous pancreas-kidney transplant. Pre-operative enhanced cytotoxicity and flow cytometry T-cell crossmatches were negative; B-cell crossmatches were not performed as per institutional protocol. The patient's post-operative course was significant for elevated serum amylase levels and development of hyperglycemia approximately 1 month after transplantation. A pancreatic biopsy at this time showed no cellular infiltrate but strong immunofluorescent staining for C4d in the interacinar capillaries. Analysis of the patient's serum identified donor-specific HLA-DR alloantibodies. He received intravenous immunoglobulin (IVIg), rituximab and plasmapheresis, and his pancreatic function normalized. We conclude that clinically significant AMR can develop in a pancreas allograft and recommend that pancreatic biopsies be assessed for C4d deposition if the patient has risk factors for AMR and/or the pathologic evidence for cell-mediated rejection is underwhelming.

Laparoscopic procurement of kidneys with multiple renal arteries is associated with increased ureteral complications in the recipient

This study investigates the effect of renal artery multiplicity on donor and recipient outcomes after laparoscopic donor nephrectomy. Three-hundred and sixty-one sequential procedures were performed over a 4-year period. Forty-nine involved accessory renal arteries; of these, 36 required revascularization and 13 were small polar vessels and ligated. The 312 remaining kidneys with single arteries served as controls. Study variables included operative times, blood loss, hospital stay, graft function and donor and recipient complications. Kidneys with multiple revascularized arteries had a longer mean warm ischemia time (35.3 vs. 29.2 min, p = 0.0003), and more ureteral complications (6/36 vs. 10/312, p = 0.0013) than single-artery controls. In contrast, ligation of a small superior accessory artery had no significant effect on donor operative time, blood loss, or complication rate while providing similar recipient graft function compared to single-artery controls. Renal artery number is important in selecting the appropriate kidney for laparoscopic procurement. Given the current excellent results with right-sided donor nephrectomy, kidneys with single arteries should be preferentially procured, irrespective of side.

BKV in simultaneous pancreas-kidney transplant recipients: a leading cause of renal graft loss in first 2 years post-transplant

With the introduction of more potent immunosuppressive agents, rejection has decreased in simultaneous pancreas/kidney transplant (SPK) recipients. However, as a consequence, opportunistic infections have increased. The purpose of this report is to outline the course of SPK patients who developed polyomavirus-associated nephropathy (PVAN). A retrospective review of 146 consecutive SPK recipients from January 1, 1996 to December 31, 2002 was performed. Immunosuppression, rejection and development of PVAN were reviewed. Nine patients were identified. All received induction with either OKT3 or thymoglobulin. Immunosuppression included tacrolimus/cyclosporine, MMF/azathioprine and sirolimus/prednisone. Two patients were treated for kidney rejection prior to the diagnosis of PVAN. Time to diagnosis was an average of 359.3 days post-transplantation. Immunosuppression was decreased but five ultimately lost function. However, none developed pancreatic abnormalities as demonstrated by normal glucose and amylase. Two underwent renal retransplantation after PVAN diagnosis and both have normal kidney function. PVAN was the leading cause of renal loss in SPK patients in the first 2 years after transplantation and is a serious concern for SPK recipients. The pancreas, however, is spared from evidence of infection, and no pancreatic rejection occurred when immunosuppression was decreased.

Laparoscopic Right Donor Nephrectomy: A Large Single-Center Experience

BACKGROUND

Laparoscopic procurement of right donor kidneys is frequently avoided or performed using hand-assist devices because of concerns regarding donor safety, adequate exposure, and vessel length. The present study describes the authors' large series of right donor nephrectomies performed laparoscopically without the use of hand ports or other manual assist devices.

METHODS

The authors retrospectively analyzed all right laparoscopic donor nephrectomies performed at their center from November 1, 1999, to February 20, 2004. Study variables included operative times, blood loss, hospital stay, graft function, and donor and recipient complications. Left donor nephrectomies performed during the same period served as controls.

RESULTS

Of 387 laparoscopic kidney procurements, 54 (14 %) were right nephrectomies. Blood loss, extraction times, length of stay, and overall complication rates were similar between right and left donor groups. The mean operative time in the right nephrectomy group was significantly shorter than in the left nephrectomy group (169 +/- 25 and 186 +/- 29 min, respectively; P = 0.003). Graft function 1 month after transplantation and the incidence of delayed graft function were similar in both groups. There was one graft loss caused by thrombosis in the left nephrectomy group; other graft-related complications in the recipients were similar in both groups.

CONCLUSIONS

This large single-center experience demonstrates that laparoscopic right donor nephrectomy performed without hand-assist devices is safe and yields kidneys with excellent function. The authors conclude that selection of the appropriate kidney for donation using this approach can be based on the same criteria that have traditionally governed open donor nephrectomy.