“
“Bifidobacterium longum NRRL B-41409 l-arabinose isomerase (l-AI) was overexpressed in Lactococcus lactis using a phosphate depletion inducible expression system. The resting L. lactis cells harboring the B. longum l-AI were used for production of d-tagatose from d-galactose in the presence of borate

buffer. Multivariable analysis suggested that high pH, temperature and borate concentration favoured the conversion of d-galactose to BVD-523 manufacturer d-tagatose. Almost quantitative conversion (92 %) was achieved at 20 g L-1 substrate and at 37.5 A degrees C after 5 days. The d-tagatose production rate of 185 g L-1 day(-1) was obtained at 300 g L-1 galactose, at 1.15 M borate, and at 41 A degrees C during 10 days when the production medium

was changed every 24 h. There was no significant loss in productivity during ten sequential 24 Baf-A1 molecular weight h batches. The initial d-tagatose production rate was 290 g L-1 day(-1) under these conditions.”
“Objective: To compare precision and apparent bias between cohort, nested case-control, self-controlled case series, case-crossover, and case-time-control study designs.

Study Design and Setting: Study designs were implemented to evaluate the association between thiazolidinediones (TZDs) and heart failure, TZDs and fracture, and liver enzyme-inducing

anticonvulsants and fracture.

Results: Effect estimates were similar for the cohort and case-control study; for the association between TZDs and fracture in women, the hazard ratio was 1.36 (1.18, 1.56) and HIF 抑制剂 odds ratio (OR) was 1.44 (1.21, 1.70). For this clinical example, the self-controlled case series gave upward bias when follow-up was censored at the outcome (incidence rate ratio [IRR], 7.08; 4.96, 10.09) but was otherwise unbiased (IRR, 1.41; 1.14, 1.75). The retrospective case-crossover OR was 3.24 (2.18, 4.80), which was reduced by either bidirectional sampling (OR, 1.20; 0.98, 1.46) or with the case-time-control design (OR, 1.40; 1.09, 1.81). Findings on apparent bias were similar for the other two clinical examples. In each clinical example, within-person designs had considerably lower precision than the cohort or case-control study designs.

Conclusion: When long-term exposures are analyzed, within-person study designs may have lower precision and greater susceptibility to bias. Bias may be reduced by sampling follow-up both before and after the outcome or with the case-time-control study design. (C) 2012 Elsevier Inc. All rights reserved.