Acute pain management in the opioid-tolerant patient.

The main goals in treating acute pain in opioid-tolerant patients are effective pain relief and prevention of withdrawal symptoms. This article provides an overview of the issues that practitioners need to consider when caring for potential and actual opioid-tolerant patients experiencing acute pain, for example following surgery or injury. It highlights the importance of a multimodal analgesic approach to pain control and the prevention of withdrawal. It defines the terminology used in managing opioid-tolerant patients in order to allay healthcare professionals' misconceptions.

Managing acute pain in opioid tolerant patients.

Managing acute pain in opioid tolerant patients can be a significant challenge. This article will provide an overview of the terminology used when managing acute pain in these patients. This understanding is essential to ensure adequate pain relief while avoiding opioid withdrawal. It is also crucial that these patients are identified and that sufficient peri- and postoperative pain management plans are formulated. This article will present an overview of the terms tolerance, physical dependence and addiction. The literature on the management of acute pain in opioid tolerant patients will be considered. Finally an audit that explores and compares the practises of a group of London hospitals, with regard to managing postsurgical pain in opioid-dependent patients will be discussed.

A database of IC50 values and principal component analysis of results from six basal cytotoxicity assays, for use in the modelling of the in vivo and in vitro data of the EU ACuteTox project.

The main aim of the ACuteTox project (part of the EU 6th Framework programme) is to demonstrate that animal tests for acute systemic toxicity can be replaced by alternative in vitro assays. In this project, data for 97 reference chemicals were collected in the AcuBase database, designed to handle deposited in vitro and in vivo (human and animal) data. To demonstrate the applicability of in vitro basal cytotoxicity tests and in vitro-in vivo modelling, it was deemed necessary to obtain data that were generated via defined standard operating procedures. The molar basal cytotoxicity IC50 values (the 50% inhibitory concentrations for the endpoint measured) for a mouse fibroblast cell line (3T3), a human hepatic cell line (HepG2), a rat hepatic cell line (Fa32), and a human neutrophil cell line (HL-60), were compared, and gave an R(2) correlation of 0.83. To identify chemicals that showed differential cytotoxicity to the various cell types involved, principal component analysis (PCA) was undertaken independently, once all the results had been returned. This showed that colchicine, cycloheximide, digoxin, 5-fluorouracil and hexachlorobenzene gave the lowest correlations with the first score vector of the PCA. The results presented are to be used to identify outliers that need to be further studied via the use of tissue-specific in vitro assays.

The effects of terahertz radiation on human keratinocyte primary cultures and neural cell cultures.

Terahertz (THz) frequencies are found in a previously underexploited region of the radiation spectrum. This non-ionising energy is now being employed in medical imaging, so the possibility of adverse effects on human skin was evaluated. Primary cultures of normal human keratinocytes (NHKs) express adhesion molecules that comprise part of the natural barrier function of the skin. The effects of exogenous agents on this barrier function can be measured. The ND7/23 cell line, which displays the characteristics of sensory neurones, can proliferate in the undifferentiated state, but can be induced to differentiate and develop neurite-like projections. Previous studies with NHK and neural cell cultures produced no evidence of the inability of these cells to differentiate and form a barrier following THz exposure. The cells were exposed to 0.14THz radiation for times varying from 10 minutes to 24 hours. For each 80-nanosecond pulse, the cells were exposed to a peak power of between 24 and 62mW/cm(2), i.e. a total energy at peak power of 345J, or 86J at average power over 24 hours. No changes in cell activity occurred, as monitored with the resazurin reduction assay, or with the barrier function of the human corneal cells, as measured with the fluorescein leakage assay. The monitoring of differentiation by using an assay for cornified envelope formation, revealed no adverse effects. Glutathione (GSH) and heat shock protein 70 levels were examined before and after differentiation, to determine the degree of the stress response, with the effects of UVB radiation as a control. UVB induced a stress response, as did heat shock treatment at 43 degrees C, whilst 0.15THz radiation, even after 24 hours of exposure, did not. Repeated exposure to THz radiation at this level, also resulted in no detectable adverse reactions.