BACKGROUND & AIMS Central adiposity has been implicated as a risk factor for Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC), possibly promoting the progression from inflammation to metaplasia and neoplasia. We performed a systematic review and meta-analysis of studies to evaluate the association between central adiposity and erosive esophagitis (EE), BE, and EAC, specifically exploring body mass index (BMI)–independent and gastroesophageal reflux (GERD)–independent effects of central adiposity on the risk of these outcomes. METHODS We performed a systematic search of multiple databases through March 2013. Studies were included if they reported effect of central adiposity (visceral adipose tissue area, waist-hip ratio, and/or waist circumference) on the risk of EE, BE, and EAC. Summary adjusted odds ratio (aOR) estimates with 95% confidence intervals (CIs), comparing highest category of adiposity with the lowest category of adiposity, were calculated by using randomeffects model. RESULTS Forty relevant articles were identified. Compared with patients with normal body habitus, patients with central adiposity had a higher risk of EE (19 studies; aOR, 1.87; 95% CI, 1.51–2.31) and BE (17 studies; aOR, 1.98; 95% CI, 1.52–2.57). The association between central adiposity and BE persisted after adjusting for BMI (5 studies; aOR, 1.88; 95% CI, 1.20–2.95). Refluxindependent association of central adiposity and BE was observed in studies that used GERD patients as controls or adjusted for GERD symptoms (11 studies; aOR, 2.04; 95% CI, 1.44–2.90). In 6 studies, central adiposity was associated with higher risk of EAC (aOR, 2.51; 95% CI, 1.54–4.06), compared with normal body habitus. CONCLUSIONS On the basis of a meta-analysis, central adiposity, independent of BMI, is associated with esophageal inflammation (EE), metaplasia (BE), and neoplasia (EAC). Its effects are mediated by reflux-dependent and reflux-independent mechanisms.

Photoacoustic (PA) imaging in the second near-infrared (NIR-II) window (1000-1700 nm) holds great promise for deep-tissue diagnosis due to the reduced light scattering and minimized tissue absorption in this region; however, exploration of such non-invasive imaging technique is greatly constrained by the lack of biodegradable NIR-II absorbing agents. We herein report the first series of metabolizable NIR-II PA agents based on semiconducting polymer nanoparticles (SPNs). Such completely organic nanoagents are composed of a πconjugated yet oxidizable optical polymer as the PA generator and a hydrolysable amphiphilic polymer as the particle matrix to provide water solubility. The obtained SPNs are readily degraded by myeloperoxidase and lipase abundant in phagocytes, transforming themselves from the non-fluorescent nanoparticles (30 nm) into the NIR fluorescent ultra-small metabolites (~ 1 nm). As such, these NIR-II PA nanoagents can be effectively cleared out via both hepatobiliary and renal excretions after systematic administration, leaving no toxicity to living mice. More importantly, the nanoagents possess the highest photothermal conversion efficiencies among all reported organic materials, and emit bright PA signals at 1064 nm, enabling sensitive NIR-II PA imaging of both subcutaneous tumor and deep brain vasculature shielded by intact skull in living mice at a low systematic dosage. This study thus provides a generalized molecular design towards organic metabolizable semiconducting materials for biomedical optical applications in the NIR-II windows.

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