Abstract 128: Leptin: A Regulator of Aldosterone Synthase Expression & Aldosterone Secretion in Visceral Adipocytes, in Mice

Obesity is associated with inappropriately high aldosterone levels, which contribute to the development of metabolic and cardiovascular disorders. The origin of these high aldosterone levels is incompletely understood. We recently demonstrated that the adipocyte-derived hormone leptin regulates aldosterone synthase (CYP11B2) expression and stimulates aldosterone release from adrenal zona glomerulosa cells. Recent studies demonstrate that adipocytes express CYP11B2 and secrete aldosterone. However, the mechanisms regulating aldosterone release from adipocytes remain unclear. Likewise, whether visceral (Visc) and subcutaneous (SubQ) adipose tissue contribute to a similar extent to aldosterone production is unknown. We tested the hypothesis that leptin increases adipocyte CYP11B2 expression and aldosterone production and investigated whether Visc and SubQ adipose tissues respond similarly to leptin. Immunostaining of mouse adipose tissue cross-sections and isolated mature adipocytes revealed that Visc and SubQ adipose tissue express leptin receptors. Treatment of mouse freshly isolated mature adipocytes, non-differenciated (stromal fraction) and differentiated adipocytes revealed that leptin dose-dependently increased CYP11B2 expression and aldosterone production in Visc adipose tissue only. Although leptin receptor and CYP11B2 levels were similar in SubQ and Visc adipocytes, SubQ adipocytes were unresponsive to leptin. The physiological relevance of these in vitro data was tested by measuring plasma aldosterone levels in mice deprived of adipose tissue (lipodystrophic mice) treated with leptin. Absence of adipose tissue in lipodystrophic mice blunted leptin-induced increases in aldosterone levels (WT-vehicle: 471±82 vs. WT-Leptin: 1699±396, p<0.05; KO-vehicle: 539±71 vs. KO+leptin: 787±156, NS). The human relevance of these data was determined by reporting that CYP11B2 expression gradually increased with body mass index in human mediastinal and omental fat depots. In summary these data strongly suggest that leptin regulates CYP11B2 levels and aldosterone release in visceral adipose tissue and that leptin-induced, adipocyte-derived aldosterone may contribute to obesity-associated hyperaldosteronism.

Identification of Psychoactive Degradants of Cannabidiol in Simulated Gastric and Physiological Fluid

Introduction: In recent research, orally administered cannabidiol (CBD) showed a relatively high incidence of somnolence in a pediatric population. Previous work has suggested that when CBD is exposed to an acidic environment, it degrades to Δ⁹-tetrahydrocannabinol (THC) and other psychoactive cannabinoids. To gain a better understanding of quantitative exposure, we completed an in vitro study by evaluating the formation of psychoactive cannabinoids when CBD is exposed to simulated gastric fluid (SGF).

Methods: Materials included synthetic CBD, Δ⁸-THC, and Δ⁹-THC. Linearity was demonstrated for each component over the concentration range used in this study. CBD was spiked into media containing 1% sodium dodecyl sulfate (SDS). Samples were analyzed using chromatography with UV and mass spectrometry detection. An assessment time of 3 h was chosen as representative of the maximal duration of exposure to gastric fluid.

Results: CBD in SGF with 1% SDS was degraded about 85% after 60 min and more than 98% at 120 min. The degradation followed first-order kinetics at a rate constant of −0.031 min⁻¹ (R²=0.9933). The major products formed were Δ⁹-THC and Δ⁸-THC with less significant levels of other related cannabinoids. CBD in physiological buffer performed as a control did not convert to THC. Confirmation of THC formation was demonstrated by comparison of mass spectral analysis, mass identification, and retention time of Δ⁹-THC and Δ⁸-THC in the SGF samples against authentic reference standards.

Conclusions: SGF converts CBD into the psychoactive components Δ⁹-THC and Δ⁸-THC. The first-order kinetics observed in this study allowed estimated levels to be calculated and indicated that the acidic environment during normal gastrointestinal transit can expose orally CBD-treated patients to levels of THC and other psychoactive cannabinoids that may exceed the threshold for a physiological response. Delivery methods that decrease the potential for formation of psychoactive cannabinoids should be explored.

Treatment of renal angiomyolipoma: pooled analysis of individual patient data

Background

This study was performed to evaluate the impact of baseline characteristics and treatment methods on the outcome of sporadic renal angiomyolipoma (AML).

Methods

This was a pooled analysis of individual data of 441 patients with AML retrieved from 58 studies and 3 institutional series.

Results

Ninety-three patients underwent nephrectomy, 163 partial nephrectomy/enucleation, 128 embolisation, 19 cryoablation, 6 radiofrequency ablation, and 32 conservative treatment. Their mean follow-up period was 44.5 months. Patients who experienced major bleeding at presentation had significantly larger tumours than did those without bleeding (mean diameter, 10.1 vs. 5.9 cm, respectively; p < 0.0001). A total of 9.4 % and 26.4 % of bleeding tumours had a diameter of <4 and <6 cm, respectively. A tumour diameter of ≥8.0 cm (hazard ratio, 2.07; 95 % confidence interval, 1.20–4.77) and the treatment method (p = 0.001) were independent predictors of re-intervention. The risk of re-intervention was significantly higher after embolisation, particularly for large tumours (5-year rate of freedom from re-intervention: diameter of ≥8.0 cm, 49.2 %; diameter of <8.0 cm, 74.8 %; p = 0.018). Conservatively treated AMLs had a mean baseline diameter of 3.2 ± 2.7 cm; after 41 months, their mean diameter was 3.7 ± 3.1 cm (p = 0.109).

Conclusions

The prevalence of major bleeding is high in sporadic AMLs with a diameter of >6 cm. These results suggest that conservative treatment can be considered in AMLs of <6 cm in diameter. Among current treatment methods, embolisation was associated with a significantly higher risk of re-intervention. Further studies are needed to define risk factors for bleeding and assess the relative benefits of different treatment modalities.

Gleason 6 Prostate Cancer: Translating Biology into Population Health

PURPOSE

Gleason 6 (3+3) is the most commonly diagnosed prostate cancer among men with prostate specific antigen screening, the most histologically well differentiated and is associated with the most favorable prognosis. Despite its prevalence, considerable debate exists regarding the genetic features, clinical significance, natural history, metastatic potential and optimal management.

MATERIALS AND METHODS

Members of the Young Urologic Oncologists in the Society of Urologic Oncology cooperated in a comprehensive search of the peer reviewed English medical literature on Gleason 6 prostate cancer, specifically focusing on the history of the Gleason scoring system, histological features, clinical characteristics, practice patterns and outcomes.

RESULTS

The Gleason scoring system was devised in the early 1960s, widely adopted by 1987 and revised in 2005 with a more restrictive definition of Gleason 6 disease. There is near consensus that Gleason 6 meets pathological definitions of cancer, but controversy about whether it meets commonly accepted molecular and genetic criteria of cancer. Multiple clinical series suggest that the metastatic potential of contemporary Gleason 6 disease is negligible but not zero. Population based studies in the U.S. suggest that more than 90% of men newly diagnosed with prostate cancer undergo treatment and are exposed to the risk of morbidity for a cancer unlikely to cause symptoms or decrease life expectancy. Efforts have been proposed to minimize the number of men diagnosed with or treated for Gleason 6 prostate cancer. These include modifications to prostate specific antigen based screening strategies such as targeting high risk populations, decreasing the frequency of screening, recommending screening cessation, incorporating remaining life expectancy estimates, using shared decision making and novel biomarkers, and eliminating prostate specific antigen screening entirely. Large nonrandomized and randomized studies have shown that active surveillance is an effective management strategy for men with Gleason 6 disease. Active surveillance dramatically reduces the number of men undergoing treatment without apparent compromise of cancer related outcomes.

CONCLUSIONS

The definition and clinical relevance of Gleason 6 prostate cancer have changed substantially since its introduction nearly 50 years ago. A high proportion of screen detected cancers are Gleason 6 and the metastatic potential is negligible. Dramatically reducing the diagnosis and treatment of Gleason 6 disease is likely to have a favorable impact on the net benefit of prostate cancer screening.

The impact of a surgical boot camp on early acquisition of technical and nontechnical skills by novice surgical trainees

BACKGROUND

Acquisition of skills early in surgical training represents a significant challenge at present because of training time constraints. The aim of this study was to investigate if an intensive surgical boot camp was effective in transferring skills at the beginning of a surgical training program.

METHODS

New core surgical trainees (n = 58) took part in a 5-day boot camp. There were pretest and posttest assessments of knowledge, technical skills, and confidence levels. The boot camp used simulation and senior surgical faculty to teach a defined range of technical and nontechnical skills.

RESULTS

The scores for knowledge (53.8% vs 68.4%, P < .01), technical skills (35.9% to 60.6% vs 50.6% to 78.2%, P < .01), and confidence levels improved significantly during boot camp. Skills improvements were still present a year later.

CONCLUSION

The 5-day surgical boot camp proved to be an effective way to rapidly acquire surgical knowledge and skills while increasing the confidence levels of trainees.