Predictors of Opioid Resistance: An Investigation in Cancer Pain.

Appropriate use of opioid analgesics according to the World Health Organization pain relief ladder has provided pain relief to many patients with cancer pain. However, a proportion of patients fail to achieve sufficient pain relief and develop opioid resistance. Individual risk factors may relate to opioid resistance. Therefore, we conducted a historical cohort study to identify risk factors for opioid resistance and to construct an index to predict it. We investigated salient factors at the time of opioid initiation in the medical records of 233 patients. The outcome was the achievement of stable pain at 14 days after opioid introduction. We identified factors contributing to opioid resistance by multivariate analysis (p < 0.05). We created a resistance score from the regression equation of the identified factors to predict opioid resistance. Forty-nine (21.0%) patients were opioid resistant without achieving the outcome. Age, neuropathic pain, and alkaline phosphatase were extracted as significant factors for opioid resistance (p < 0.05). A resistance score was created from these factors and classified into binary values, the sensitivity was 80.6% and the negative predictive value was 91.6%. The findings suggest that the resistance score could be a sensitive predictor of opioid resistance before opioid initiation.

Predictive Factors of Opioid-Induced Nausea in Cancer Patients.

Approximately 30% of patients experience nausea after initiation of opioid therapy, which can lead to poor quality of life. We aimed to identify risk factors for opioid-induced nausea at the initiation of opioid therapy by conducting a retrospective review of medical records of patients diagnosed by palliative care specialists with solid cancer and pain at the lesion site at Showa University Hospital between June 2005 and June 2011. The primary endpoint was the development of nausea grade ≥1 according to the Common Terminology Criteria for Adverse Events version 4.0 within 48 hours of initiation of opioid therapy. The median age of the 134 enrolled patients was 67.7 (range 28-95) years. Fifty-three percent were male and 44% had gastrointestinal cancer. Furthermore, 22.4% had opioid-induced nausea. Age (odds ratio (OR) 1.74; 95% confidence interval (CI), 1.13-2.69), edema (OR 5.83; 95% CI, 1.22-28.19), and gastrointestinal cancer (OR 2.61, 95% CI 1.07-6.36) were significantly associated with opioid-induced nausea. Prophylactic antiemetics were found to be ineffective.

Zinc benzoate, a contaminating environmental compound derived from polystyrene resin inhibits A-type monoamine oxidase.

The contaminants in deionized and distilled water (DDI water) boiled with polystyrene resin inhibited A-type monoamine oxidase (MAO, MAO-A preferentially deaminates serotonin and norepinephrine and regulates these amines concentration) activity in monkey brain mitochondria. To identify these contaminants, we attempted measurements by HPLC, FT-IR and NMR. The compound inhibiting MAO-A activity was zinc benzoate. Although it potently inhibited MAO-A activity, zinc benzoate did not effect MAO-B in monkey brain mitochondria. It also reversibly and competitively inhibited MAO-A activity in a dose-dependent manner. Zinc benzoate, however, did not inhibit either MAO-A or -B activities in rat brain mitochondria. These results indicate that zinc benzoate, which inhibits MAO-A activity, is easily incorporated in DDI water by boiling polystyrene and also may be a contaminating environmental chemical compound that alters the levels of serotonin and norepinephrine in the central nervous system.

Calcium disodium edetate enhances type A monoamine oxidase activity in monkey brain.

The effects of metal chelators on monoamine oxidase (MAO) isozymes, MAO-A and MAO-B, in monkey brain mitochondria were investigated in vitro. MAO-A activity increased to about 40% with 0.1 microM calcium disodium edetate (CaNa2EDTA) using serotonin as a substrate, and this activation was proportional to the concentration of CaNa2EDTA. On the other hand, MAO-A activities were decreased gradually with an increasing concentration of o-phenanthroline and diethyldithiocarbamic acid, but these metal chelators had no effect on MAO-B activity in monkey brain. The activation of MAO-A activity by CaNa2EDTA was reversible. CaNa2EDTA did not activate both MAO-A and MAO-B activities in rat brain mitochondria. Zn and Fe ions were found in the mitochondria of monkey brain. Zn ions potently inhibited MAO-A activity, but Fe ions did not inhibit either MAO-A or MAO-B activity in monkey brain mitochondria. These results indicate that the activating action of CaNa2EDTA on MAO-A was the result of the chelating of Zn ions contained in mitochondria by CaNa2EDTA. These results also indicate the possibility that Zn ions may regulate physiologically the level of serotonin and norepinephrine content in brain by inhibiting a MAO-A activity.

The transcription factor CCAAT-binding factor CBF/NF-Y regulates the proximal promoter activity in the human alpha 1(XI) collagen gene (COL11A1).

We have characterized the proximal promoter region of the human COL11A1 gene. Transient transfection assays indicate that the segment from -199 to +1 is necessary for the activation of basal transcription. Electrophoretic mobility shift assays (EMSAs) demonstrated that the ATTGG sequence, within the -147 to -121 fragment, is critical to bind nuclear proteins in the proximal COL11A1 promoter. We demonstrated that the CCAAT binding factor (CBF/NF-Y) bound to this region using an interference assay with consensus oligonucleotides and a supershift assay with specific antibodies in an EMSA. In a chromatin immunoprecipitation assay and EMSA using DNA-affinity-purified proteins, CBF/NF-Y proteins directly bound this region in vitro and in vivo. We also showed that four tandem copies of the CBF/NF-Y-binding fragment produced higher transcriptional activity than one or two copies, whereas the absence of a CBF/NF-Y-binding fragment suppressed the COL11A1 promoter activity. Furthermore, overexpression of a dominant-negative CBF-B/NF-YA subunit significantly inhibited promoter activity in both transient and stable cells. These results indicate that the CBF/NF-Y proteins regulate the transcription of COL11A1 by directly binding to the ATTGG sequence in the proximal promoter region.