Racial differences in weight loss, hemoglobin A1C, and blood lipid profiles after Roux-en-Y gastric bypass surgery

BACKGROUND

It is known that African American (AA) patients with obesity achieve less weight loss after Roux-en-Y gastric bypass surgery (RYGB) than their Caucasian (CA) counterparts. However, it is unclear how these differences in weight loss are reflected in clinical outcomes.

OBJECTIVES

To determine the effects of RYGB on hemoglobin A_1c (A_1c) and blood lipids in relationship to the variability in weight loss outcomes in a racially mixed patient population.

SETTING

University medical center.

METHODS

Retrospective analysis of clinical data from electronic medical records of CA, AA, and Hispanic American (HA) patients undergoing RYGB.

RESULTS

We used 2-way cluster analysis and identified 4 distinct weight loss×race clusters. CA patients separated into 2 clusters (45.5% and 28.2% weight loss, respectively), whereas, AA and HA patients separated into 1 cluster each (33.2% and 34.4% weight loss, respectively). Factors that significantly affected weight loss were race, age, gender, and physical activity as well as presence of hypertension and degenerative joint disease. Although all clusters had significant improvements in blood lipids, HA had an increase in total cholesterol (Total-c) and low-density lipoprotein cholesterol (LDL-c) at 2 years after surgery. All clusters had significant decreases in A_1c in the first year. At 2 years after RYGB, A_1c levels remained stable in CA and HA; however, AA had a significant increase. These racial differences in A_1c could not be explained by the smaller weight loss in AA patients.

CONCLUSION

Race is an important factor in the clinical outcomes of RYGB, especially in regard to diabetes control; however, its effect is not completely understood.

A Multifaceted Intervention to Increase Surgery Resident Engagement in Reporting Adverse Events

BACKGROUND

Although most residents have been involved in an adverse or near-miss event, they are not likely to report these incidents. To improve the culture of patient safety and to increase adverse event reporting among General Surgery residents, a multifaceted intervention focused on education, feedback, and event resolution was developed and implemented.

METHODS

Adverse events involving surgery patients at Boston Medical Center were monitored for 2 months before and for 10 months after implementation of the intervention in May 2014.

RESULTS

There was a significant increase in the number of adverse events reported by residents, from 0 to 30 per 2-month period (χ(2) = 8.56, p = 0.003). The classification types of reports filed by residents differed significantly from those of incidents submitted by other reporters (p < 0.0001).

CONCLUSION

An intervention focused on addressing barriers to reporting adverse events can significantly increase the volume of incidents reported by surgery residents. Involving residents in patient safety efforts may enhance an institution's ability to identify adverse events and to improve the overall culture of care.

Improved Insulin Sensitivity 3 Months After RYGB Surgery Is Associated With Increased Subcutaneous Adipose Tissue AMPK Activity and Decreased Oxidative Stress

Morbidly obese individuals are predisposed to a wide range of disorders, including type 2 diabetes, atherosclerotic cardiovascular disease, fatty liver disease, and certain cancers. Remarkably, all of these disorders can be improved or prevented by Roux-en-Y gastric bypass (RYGB) surgery. We have reported that decreased AMPK activity, together with increased oxidative stress and inflammation in adipose tissue, is associated with insulin resistance in morbidly obese bariatric surgery patients. In the current study, we assessed how these parameters are affected by RYGB surgery. Eleven patients (average age of 46 ± 4 years) were studied immediately prior to surgery and 3 months postoperatively. We measured subcutaneous adipose tissue AMPK phosphorylation (threonine 172, an index of its activation), malonyl-CoA content, protein carbonylation (a marker of oxidative stress), plasma adiponectin, and mRNA expression of several inflammatory cytokines. After surgery, AMPK activity increased 3.5-fold and oxidative stress decreased by 50% in subcutaneous adipose tissue. In addition, malonyl-CoA levels were reduced by 80%. Furthermore, patients had improvements in their BMI and insulin sensitivity (HOMA) and had increased circulating high-molecular weight adiponectin and decreased fasting plasma insulin levels. In contrast, the expression of inflammatory markers in subcutaneous adipose tissue was unchanged postoperatively, although plasma CRP was diminished by 50%.

Integrative population pharmacokinetic and pharmacodynamic dose finding approach of the new camptothecin compound namitecan (ST1968)

AIMS

Namitecan is a new camptothecan compound undergoing early clinical development. This study was initiated to build an integrated pharmacokinetic (PK) and pharmacodynamic (PD) population model of namitecan to guide future clinical development.

METHODS

Plasma concentration-time data, neutrophils and thrombocytes were pooled from two phase 1 studies in 90 patients with advanced solid tumours, receiving namitecan as a 2 h infusion on days 1 and 8 every 3 weeks (D1,8) (n = 34), once every 3 weeks (D1) (n = 29) and on 3 consecutive days (D1-3) (n = 27). A linear three compartment PK model was coupled to a semiphysiological PD-model for neutrophils and thrombocytes. Data simulations were used to interrogate various dosing regimens and give dosing recommendations.

RESULTS

Clearance was estimated to be 0.15 l h(-1), with a long terminal half-life of 48 h. Body surface area was not associated with clearance, supporting flat-dosing of namitecan. A significant and clinically relevant association was found between namitecan area under the concentration-time curve (AUC) and the percentage drop of neutrophils (r(2) = 0.51, P < 10(-4)) or thrombocytes (r(2) = 0.49, P < 10(-4)). With a target for haematological dose-limiting toxicity of <20%, the recommended dose was defined as 12.5 mg for the D1,8 regimen, 23 mg for the once every 3 week regimen and 7 mg for the D1-3 regimen.

CONCLUSION

This is the first integrated population PK-PD analysis of the new hydrophilic topoisomerase I inhibitor namitecan, that is currently undergoing early clinical development. A distinct relationship was found between drug exposure and haematological toxicity, supporting flat-dosing once every 3 weeks as the most adequate dosing regimen.

Treatment of idiopathic intracranial hypertension with gastric bypass surgery

Idiopathic intracranial hypertension (IIH) is defined by elevated intracranial pressure and associated headaches, changes in vision and pulsatile tinnitus, among other symptoms. It occurs most frequently in young, obese women. Gastric bypass surgery has been used to treat morbid obesity and its comorbidities, and IIH has recently been considered among these indications. We present a case report of a 29-year-old female with a maximum BMI of 50.3 and a 5-year history of severe headaches and moderate papilledema due to IIH. She also developed migraine headaches. After a waxing and waning course and various medical treatments, the patient underwent laparoscopic Roux-en-Y gastric bypass surgery with anterior repair of hiatal hernia. Dramatic improvement in IIH headaches occurred by 4 months postprocedure and was maintained at 1 year, when she reached her weight plateau with a BMI of 35. Presurgery migraines persisted. This adds to the small number of case reports and retrospective analyses of the successful treatment of IIH with gastric bypass surgery, and brings this data from the surgical literature into the neurological domain. It offers insight into an early time course for symptom resolution, and explores the impact of weight-loss surgery on migraine headaches. This treatment modality should be further investigated prospectively to analyze the rate of headache improvement with weight loss, the amount of weight loss needed for clinical improvement, and the possible correlation with improvement in papilledema.

Heterozygosity for an inactivating mutation in low-density lipoprotein-related receptor 6 (Lrp6) increases osteoarthritis severity in mice after ligament and meniscus injury

OBJECTIVE

Wnt/β-catenin signaling plays an integral and complex role in cartilage development and maintenance. β-catenin signaling has been linked to osteoarthritis (OA), but the role of Lrp6-mediated Wnt/β-catenin signaling during OA remains unexplored. Mutations in the Wnt/β-catenin co-receptors LRP5 and LRP6 (low-density lipoprotein-related receptors 5 and 6) result in skeletal abnormalities, which tend to be more severe in Lrp6 mutant mice. We examined OA development, chondrocyte and osteoblast behavior, and β-catenin signaling after ligament and meniscus damage in mice with global heterozygous deletion of Lrp6.

DESIGN

Ligament and meniscus damage was surgically induced in Lrp6(+/-) and wild-type (WT) mice, and evidence of joint disease was assessed by Microcomputed tomography (micro-CT) and histology. Wnt/β-catenin signaling, proliferation, apoptosis, chondrogenesis, osteogenesis, and catabolic enzyme activity were measured.

RESULTS

Relative to WT mice, Lrp6(+/-) mice had lower nuclear β-catenin signaling within articular cartilage. After surgery, osteophytes and reduced articular cartilage were apparent in WT mice, but more severe in Lrp6(+/-) animals. Impairments to trabecular bone geometry occurred for WT and Lrp6(+/-) mice after surgery. Relative to WT mice, Lrp6(+/-) mice had reduced trabecular BMD and thickness, and Cyclin D1 and Lrp6 gene expression after surgery. There was an increase in apoptotic cells and serum matrix metalloproteinase-9 (MMP9) for Lrp6(+/-) mice after surgery, but no differences in cell proliferation occurred.

CONCLUSIONS

Heterozygous loss-of-function mutation in Lrp6 leads to less β-catenin signaling within articular cartilage and to increased degenerative joint disease after ligament and meniscus injury. Modulation of Lrp6 function could attenuate joint disease after damage to ligaments and the meniscus.

Multiscale Simulations of Brittle Fracture and the Quantum-Mechanical Nature of Bonding in Silicon

We simulate the microscopic details of brittle fracture in silicon by dynamically coupling empirical-potential molecular dynamics of a strained sample to a quantum-mechanical description of interatomic bonding at the crack tip. Our simulations show brittle fracture at loads comparable to experiment, in contrast with empirical potential simulations that show only ductile crack propagation at much higher loading. While the ductility of the empirical potentials can be attributed to their short range, it is unclear whether the increased range of the tight-binding description is sufficient to explain its brittle behavior. Using the multiscale method we show that at a temperature of 1100 K, but not at 900 K, a dislocation is sometimes nucleated when the crack tip impinges on a vacancy. While this result is too limited in length and time scales to directly correspond to experimental observations, it is suggestive of the experimentally observed brittle to ductile transition.