Superior gallstone dissolubility and safety of tert-amyl ethyl ether over methyl-tertiary butyl ether

BACKGROUND The use of methyl-tertiary butyl ether(MTBE)to dissolve gallstones has been limited due to concerns over its toxicity and the widespread recognition of the safety of laparoscopic cholecystectomy.The adverse effects of MTBE are largely attributed to its low boiling point,resulting in a tendency to evaporate.Therefore,if there is a material with a higher boiling point and similar or higher dissolubility than MTBE,it is expected to be an attractive alternative to MTBE.AIM To determine whether tert-amyl ethyl ether(TAEE),an MTBE analogue with a relatively higher boiling point(102°C),could be used as an alternative to MTBE in terms of gallstone dissolubility and toxicity.METHODS The in vitro dissolubility of MTBE and TAEE was determined by measuring the dry weights of human gallstones at predetermined time intervals after placing them in glass containers with either of the two solvents.The in vivo dissolubility was determined by comparing the weights of solvent-treated gallstones and control(dimethyl sulfoxide)-treated gallstones,after the direct infusion of each solvent into the gallbladder in both hamster models with cholesterol and pigmented gallstones.RESULTS The in vitro results demonstrated a 24 h TAEE-dissolubility of 76.7%,56.5%and 38.75%for cholesterol,mixed,and pigmented gallstones,respectively,which represented a 1.2-,1.4-,and 1.3-fold increase in dissolubility compared to that of MTBE.In the in vitro experiment,the 24 h-dissolubility of TAEE was 71.7%and 63.0%for cholesterol and pigmented gallstones,respectively,which represented a 1.4-and 1.9-fold increase in dissolubility compared to that of MTBE.In addition,the results of the cell viability assay and western blot analysis indicated that TAEE had a lower toxicity towards gallbladder epithelial cells than MTBE.CONCLUSION We demonstrated that TAEE has higher gallstone dissolubility properties and safety than those of MTBE.As such,TAEE could present an attractive alternative to MTBE if our findings regarding its efficacy and safety can be consistently reproduced in further subclinical and clinical studies.

Gender Differences in Rapid Eye Movement-Related Sleep Disordered Breathing

Sleep disordered breathing (SDB) is an independent risk factor for cardiovascular disease. It is known to be associated more frequently with men than women, particularly in the premenopausal age range. The goal of this study is to evaluate gender differences among Korean patients diagnosed with SBD. This study included 309 patients who visited our Sleep Clinic due to sleep-related symptoms and were diagnosed with SDB by overnight polysomnography (PSG). We analyzed age, gender, body mass index, various PSG indices including sleep stages, apnea-hypopnea index (AHI) and AHI ratio in rapid eye movement (REM) versus non-REM (NREM) sleep stages (R:N ratio). Of those 309 patients diagnosed with obstructive sleep apnea, 217 (70.2%) were men (mean age 51.05 ± 12.64 years) and 92 (29.8%) were women (mean age 64.53 ± 10.43 years). The mean AHI during total sleep time was 30.34 ± 21.17 in men and 21.47 ± 17.14 in women (P P P = 0.402). REM SDB with R:N ratio higher than 2.0 was more frequently observed in women than in men, 34.8% (32/92) of women, compared with 11.9% (26/217) in men (P 60 years old. These findings suggest the possibility of different pathophysiologic mechanisms of SDB between genders and also between NREM versus REM sleep, which can be partly explained by the influence of female sex hormones.