Concentration-dependent modulation of amyloid-beta in vivo and in vitro using the gamma-secretase inhibitor, LY-450139

LY-450139 is a gamma-secretase inhibitor shown to have efficacy in multiple cellular and animal models. Paradoxically, robust elevations of plasma amyloid-beta (Abeta) have been reported in dogs and humans after administration of subefficacious doses. The present study sought to further evaluate Abeta responses to LY-450139 in the guinea pig, a nontransgenic model that has an Abeta sequence identical to that of human. Male guinea pigs were treated with LY-450139 (0.2-60 mg/kg), and brain, cerebrospinal fluid, and plasma Abeta levels were characterized at 1, 3, 6, 9, and 14 h postdose. Low doses significantly elevated plasma Abeta levels at early time points, with return to baseline within hours. Higher doses inhibited Abeta levels in all compartments at early time points, but elevated plasma Abeta levels at later time points. To determine whether this phenomenon occurs under steady-state drug exposure, guinea pigs were implanted with subcutaneous minipumps delivering LY-450139 (0.3-30 mg/kg/day) for 5 days. Plasma Abeta was significantly inhibited at 10-30 mg/kg/day, but significantly elevated at 1 mg/kg/day. To further understand the mechanism of Abeta elevation by LY-450139, H4 cells overexpressing the Swedish mutant of amyloid-precursor protein and a mouse embryonic stem cell-derived neuronal cell line were studied. In both cellular models, elevated levels of secreted Abeta were observed at subefficacious concentrations, whereas dose-responsive inhibition was observed at higher concentrations. These results suggest that LY-450139 modulates the gamma-secretase complex, eliciting Abeta lowering at high concentrations but Abeta elevation at low concentrations.     

beta(2)-Adrenergic stimulation attenuates left ventricular remodeling, decreases apoptosis, and improves calcium homeostasis in a rodent model of ischemic cardiomyopathy

The benefit of the beta(2)-adrenergic agonist, clenbuterol, in left ventricular assist device patients with dilated cardiomyopathy has been reported, but its effect on ischemic heart failure (HF) is unknown. We investigated whether clenbuterol improves left ventricular remodeling, myocardial apoptosis and has synergy with a beta(1) antagonist, metoprolol, in a model of ischemic HF. Rats were randomized to: 1) HF only; 2) HF + clenbuterol; 3) HF + metoprolol; 4) HF + clenbuterol + metoprolol; and 5) rats with sham surgery. HF was induced by left anterior descending artery (LAD) artery ligation and confirmed by decreased left ventricular fractional shortening, decreased maximum left ventricular dP/dt (dP/dt(max)), and elevated left ventricular end-diastolic pressure (LVEDP) compared with sham rats (p < 0.01). After 9 weeks of oral therapy, echocardiographic, hemodynamic, and ex vivo end-diastolic pressure-volume relationship (EDPVR) measurements were obtained. Immunohistochemistry was performed for myocardial apoptosis and DNA damage markers. Levels of calcium-handling proteins were assessed by Western blot analysis. Clenbuterol-treated HF rats had increased weight gain and heart weights versus HF rats (p < 0.05). EDPVR curves revealed a leftward shift in clenbuterol rats versus metoprolol and HF rats (p < 0.05). The metoprolol-treated group had a lower LVEDP and higher dP/dt(max) versus the HF group (p < 0.05). Clenbuterol and metoprolol groups had decreased myocardial apoptosis and DNA damage markers and increased DNA repair markers versus HF rats (all p < 0.01). Protein levels of the ryanodine receptor and sarcoplasmic reticulum calcium-ATPase were improved in clenbuterol-, metoprolol-, and clenbuterol+metoprolol-treated groups versus HF rats. However, as a combination therapy, there were no synergistic effects of clenbuterol+metoprolol treatment. We conclude that clenbuterol ameliorates EDPVR, apoptosis, and calcium homeostasis but does not have synergy with metoprolol in our model of ischemic HF.     

Meta-analysis of short-term outcomes after laparoscopic resection for rectal cancer

Background Laparoscopic resection (LR) has become increasingly popular for the management of rectal cancer. Despite a decade of experience, the safety and efficacy of LR for rectal cancer remains to be established. This report performs a meta-analysis to compare LR with conventional open resection (CR) in patients with rectal cancer.Methods Using a defined search strategy, studies directly comparing CR with LR for rectal cancer were identified. The data for patients with rectal cancer treated with both approaches were extracted and used in our meta-analysis. Open surgery and laparoscopic surgery were compared in terms of postoperative mortality, morbidity, complications, oncological clearance, operating time, and time before recovery to a normal diet.Results Compared with CR, LR is associated with lower morbidity rates [OR 0.63 (0.41, 1.96) P=0.03], longer operating times [weighted mean difference 1.59 (1.20, 1.98) P<0.00001], similar mortality rates, wound healing disorder rates, urinary disorder rates, cardiopulmony disease rates, all leakage rates, all abscess rates and a positive rate of margin.Conclusion LR is associated with less postoperative morbidity, but longer operation time. A prospective randomized controlled trial is warranted to fully investigate these and other outcome measures.     

Risk factors for incident Alzheimer's disease in African Americans and Yoruba

Introduction: The incidence rate of Alzheimer's disease (AD) was found to be 2 times lower in Yoruba than in African Americans. This study was aimed at identifying the factors associated with increased risk of incident AD in the two communities. Methodology: A two-stage design with initial screening using the CSI’D followed by neuropsychological test battery, relations’ interview and physician assessment in a sub-sample. NINCDS-ADRDA criteria were met for AD. The risk factor variables assessed included demographic, lifestyle, medical and family history items. Results: In the Yoruba, AD was associated with age (OR = 1.07) and female gender (OR = 2.93). In African Americans, age (OR = 1.09) and rural living (OR = 2.08) were the significant risk factors, while alcohol was protective (OR = 0.49). Discussion: Age was a significant risk factor for AD at both sites. The higher risk of incident AD in the Yoruba female, and in African Americans who resided in rural areas in childhood were similar with the prevalence cases. Alcohol emerged a protective factor in African Americans. More studies are required, including biological measurements, to adequately explain the differences in rates.     

非血缘关系骨髓及外周造血干细胞移植的比较

目的比较非血缘关系骨髓(UBMT)及外周造血干细胞移植(UPBSCT)在移植疗效方面的差异。方法63例患者分为UBMT组30例,UPBSCT组33例。两组均采用本所的加强方案预防移植物抗宿主病(GVHD)的发生。所有患者在预处理阶段都应用了抗T细胞免疫球蛋白(ATG)或CD_3单抗,但UPBSCT组以兔源性的ATG为主(21/33),而UBMT组以猪源性的ATG为主(17/25,P=0.02)。结果UBMT和UPBSCT组分别有28/30例和32/33例患者达到完全稳定的供者植入,UBMT组输入单个核细胞中位数(2.80×10~8/kg)少于UPBSCT组(6.16×10~8/kg,P＜0.05),WBC和PLT的中位植活时间长于UPBSCT组(17d比11d;27.5d比14d,P＜0.01)。两组≥Ⅱ度急性GVHD的累积发生率分别为66.7%和33.0%;其中Ⅲ-Ⅳ度为34.5%和7.3%(P＜0.05)。在对两组ATG的来源进行分层分析后发现急性GVHD的发生率没有统计差异。两组慢性GVHD的发生率分别为63.6%(14/22)、72.0%(18/25),其中广泛型分别为7例和5例,差异无统计学意义(P＞0.05)。UBMT和UPBSCT组巨细胞病毒(CMV)血症和CMV疾病的发生率分别为60.0%％(18/30)、43.3%(13/30);60.6%(20/33)、15.1%(5/33)。截至2005年6月,UBMT复发4例,死亡15例,总体生存率(OS)为47.22%,UPBSCT组复发6例,死亡8例,OS为62.45%。1年的总生存率分别为53.13%、78.06%(P=0.05),总的移植相关病死率分别为51.52%、19.68%(P=0.06)。结论UPBSCT同骨髓移植相比,造血重建快,并不增加急性GVHD的发生,两组生存率相近。