Predictors of heroin abstinence in opiate substitution therapy in heroin-only users and dual users of heroin and crack.

AIMS: To analyse predictors of heroin abstinence in opiate substitution therapy (OST) based on frequency of crack use and its interactions with other predictors in a clinical non-experimental setting. DESIGN: Retrospective study. SETTING: A community drug service in London, UK. PARTICIPANTS: 325 clients starting OST between 2010 and 2014 (197 methadone and 128 buprenorphine). MEASUREMENTS: Logistic regression models (a general model and separate models for methadone and buprenorphine) assessed demographic and clinical data as predictors of heroin abstinence at one year after treatment start (or at the date of transfer to another service). FINDINGS: For the general model participants choosing methadone were more likely to use heroin at follow up (OR=2.36, 95% CI: 1.40-3.17) as were daily crack users on methadone (OR=2.62, 95% CI: 0.96-7.16). For the methadone model only daily crack use predicted heroin use at follow up (OR=2.62, 95% CI: 0.96-7.16). For buprenorphine, higher amounts of baseline heroin use, lower buprenorphine dose and daily drinking predicted heroin use at follow up (OR=0.85, 95% CI: 0.75-0.95; OR=1.31, 95% CI: 1.06-1.60 and OR=6.04, 95% CI: 1.26-28.92). Both use of cannabis and depression increased likelihood of heroin abstinence for clients not using crack compared to occasional (OR=6.68, 95% CI: 0.37-119.59; OR=106.31, 95% CI: 3.41-3313.30) and daily (OR=57.49 (95% CI: 2.37-1396.46; OR=170.99 (95% CI: 4.61-6339.47) users. CONCLUSIONS: Most of the predictors in the general model were found significant only in the buprenorphine but not in the methadone model, suggesting that a general model has little predictive value. Crack use was a significant predictor of heroin abstinence at follow up in all models, however for buprenorphine only when depression or cannabis use was present. Further research is needed to assess effective treatment approaches for the growing population of dual users.

Improved protocols for protein and RNA isolation from three-dimensional collagen sandwich cultures of primary hepatocytes.

The sandwich culture is the most widely used long-term culture system for functional primary hepatocytes. Despite its advantages, the currently available protocols for protein and RNA extraction are either time-consuming or contain steps that may skewer the results. This paper describes improved protocols for RNA and protein extraction from sandwich cultures that are easy to perform, require short working time, and use no additional enzymatic reactions that could change the expression profile of the cells. The quality of the RNA is excellent, allowing also applications requiring high purity such as microarrays. In general, the protocols are suited for any cells in 3D collagen culture.

Improved semiquantitative Western blot technique with increased quantification range.

With the development of new interdisciplinary fields such as systems biology, the quantitative analysis of protein expression in biological samples gains more and more importance. Although the most common method for this is ELISA, Western blot also has advantages: The separation of proteins by size allows the evaluation of only specifically bound protein. This work examines the Western blot signal chain, determines some of the parameters relevant for quantitative analysis and proposes a mathematical model of the reaction kinetics. Using this model, a semiquantitative Western blot method for simultaneous quantification of different proteins using a hyperbolic calibration curve was developed. A program was written for the purpose of hyperbolic regression that allows quick determination of the calibration curve coefficients. This program can be used also for approximation of calibration curves in other applications such as ELISA, BCA or Bradford assays.