Brain available dopamine D2 binding appears to increase following GBP. This preliminary finding needs to be replicated in a larger population but suggests that diminished D2 binding in the obese may be due to D2 receptor downregulation. Changes in available dopamine receptor binding may play an important role in centrally mediated appetite suppression and resultant weight loss after LGBP.

Male sex, obesity, and age are risk factors for obstructive sleep apnea, although the mechanisms by which these factors increase sleep apnea susceptibility are not entirely understood. This study examined the interrelationships between sleep apnea risk factors, upper airway mechanics, and sleep apnea susceptibility. In 164 (86 men, 78 women) participants with and without sleep apnea, upper airway pressure-flow relationships were characterized to determine their mechanical properties [pharyngeal critical pressure under hypotonic conditions (passive Pcrit)] during non-rapid eye movement sleep. In multiple linear regression analyses, the effects of body mass index and age on passive Pcrit were determined in each sex. A subset of men and women matched by body mass index, age, and disease severity was used to determine the sex effect on passive Pcrit. The passive Pcrit was 1.9 cmH(2)O [95% confidence interval (CI): 0.1-3.6 cmH(2)O] lower in women than men after matching for body mass index, age, and disease severity. The relationship between passive Pcrit and sleep apnea status and severity was examined. Sleep apnea was largely absent in those individuals with a passive Pcrit less than -5 cmH(2)O and increased markedly in severity when passive Pcrit rose above -5 cmH(2)O. Passive Pcrit had a predictive power of 0.73 (95% CI: 0.65-0.82) in predicting sleep apnea status. Upper airway mechanics are differentially controlled by sex, obesity, and age, and partly mediate the relationship between these sleep apnea risk factors and obstructive sleep apnea.

VBLOC® therapy to treat morbid obesity was safe, but weight loss was not greater in treated compared to controls; clinically important weight loss, however, was related to hours of device use. Post-study analysis suggested that the system electrical safety checks (low charge delivered via the system for electrical impedance, safety, and diagnostic checks) may have contributed to weight loss in the control group.

Although Roux-en-Y gastric bypass surgery (RYGBP) is safe and effective at achieving weight loss in the majority of severely obese patients, a subset fails to achieve expected weight loss outcomes. Factors associated with poor weight loss are not well defined. Patients undergoing open RYGBP using a standardized surgical technique and clinical pathway by a single surgeon at a dedicated bariatric center were reviewed. Suboptimal weight loss was defined as failure to lose at least 40% excess body weight by 12 months postoperatively. Of 555 consecutive patients who underwent RYGBP from 1999 to 2004, a 12-month follow-up was available for the 495 (89%). Suboptimal weight loss occurred in 55 (11%) and was associated on unadjusted bivariate analysis with increased body mass index (BMI; p = 0.0002), diabetes mellitus (p = 0.0002), Medicaid insurance (p = 0.04), and male sex (p = 0.01). On adjusted multivariate analysis, increased BMI (p = 0.003), diabetes (p = 0.002), and male gender (p = 0.04) were associated with suboptimal weight loss, but type of insurance (p = 0.11) was not. Medicaid patients were younger (p = 0.01) and had higher BMI (p = 0.0002). Suboptimal weight loss after RYGBP appears to be associated with greater BMI, male sex, and diabetes but not type of insurance. This study may help identify patients who could benefit from increased perioperative education and counseling or selection of procedures with greater malabsorption.