Yiliam Rodriguez

Prophylactic and antinociceptive effects of coenzyme Q10 on diabetic neuropathic pain in a mouse model of type 1 diabetes.

Background:Oxidative stress is a key factor implicated in the development of diabetic neuropathy. This study evaluates the prophylactic and antinociceptive effects of the antioxidant coenzyme Q10 (CoQ10) on diabetes-induced neuropathic pain in a diabetic mouse model. Methods:Total 56 mice with type 1 diabetes induced by streptozotocin were used, 20 normal mice were used as control. Mechanical and thermal nociceptive behavioral assays were applied to evaluate diabetic neuropathic pain. Tissue lipid peroxidation, immunohistochemistry, reverse transcription, and polymerase chain reaction were used to evaluate the molecular mechanisms of CoQ10. Data are presented as mean ± SEM. Results:CoQ10 administration was associated with reduced loss of body weight compared with nontreated diabetic mice, without affecting blood glucose levels. Low dose and long-term administration of CoQ10 prevented the development of neuropathic pain. Treatment with CoQ10 produced a significant dose-dependent inhibition of mechanical allodynia and thermal hyperalgesia in diabetic mice. Dorsal root ganglia, sciatic nerve, and spinal cord tissues from diabetic mice demonstrated increased lipid peroxidation that was reduced by CoQ10 treatment. CoQ10 administration was also noted to reduce the proinflammatory factors in the peripheral and central nervous system. Conclusions:The results of this study support the hypothesis that hyperglycemia induced neuronal oxidative damage and reactive inflammation may be pathogenic in diabetic neuropathic pain. CoQ10 may be protective by inhibiting oxidative stress and reducing inflammation by down-regulating proinflammatory factors. These results suggest that CoQ10 administration may represent a low-risk, high-reward strategy for preventing or treating diabetic neuropathy.

CYP2D6 poor metabolizer genotype and smoking predict severe postoperative pain in female patients on arrival to the recovery room.

UNLABELLED Recent studies have shown that CYP2D6 acts at critical steps for endogenous morphine biosynthesis. The present study assessed the contribution of CYP2D6 genetic polymorphisms, smoking, and other factors on acute severe postoperative pain (linear analog pain scores ≥8). METHODS Two hundred thirty-six female patients were found to have adequate information in a previously developed female surgical patient database to be included in this current analysis. Multiple logistic regression analysis was used to assess the predictors for acute severe postoperative pain. DNA had been previously extracted from blood samples in all patients and was genotyped by the Amplichip to determine the specific CYP2D6 genotypes. RESULTS It was noted that the incidence of acute severe postoperative pain (linear analog pain scores ≥8) was more frequent in patients with the CYP2D6 poor metabolizer (PM) genotype, 71%, compared with 28% in intermediate metabolizers (IMs), 26% in extensive metabolizers (EMs), and 27% in ultrarapid metabolizers (UMs). The overall association between metabolizer groups and severe postoperative pain was significant (P=0.023). PMs were significantly more likely to suffer from severe postoperative pain than IMs, EMs, and UMs (P=0.007, 0.002, and 0.050, respectively). There were no significant differences among IMs, EMs, and UMs. Additionally, it was noted that there was an increased frequency of acute severe postoperative pain in smokers vs nonsmokers (P=0.014). CONCLUSION This study demonstrated that female patients possessing the PM genotype of CYP2D6 and patients who smoke had a higher incidence of acute severe postoperative pain.

Polymorphism in the interleukin-1 receptor antagonist gene is associated with serum interleukin-1 receptor antagonist concentrations and postoperative opioid consumption

BACKGROUND The interleukin-1 receptor antagonist (IL-1Ra) is the principal determinant of IL-1β bioactivity within the IL-1 gene cluster, regulating IL-1α and IL-1β release. This study was designed to determine whether polymorphisms of the IL-1Ra gene (IL1RN) produce clinically measurable differences in serum IL-1Ra concentrations and opioid consumption in the postoperative period. METHODS Opioid consumption and pain scores were evaluated in 96 patients undergoing a nephrectomy. DNA was extracted from all patients, and the genotypes of IL1RN were determined by polymerase chain reaction amplification of the variable number of tandem repeats of 86 base pairs in intron 2 of IL1RN. The concentrations of serum IL-1Ra concentrations at baseline and at 24 h postoperatively in 58 subjects were measured. RESULTS Differences in opioid consumption among the three genotype groups (IL1RN*1 homozygotes and *2 and *3 carriers) were statistically significant in the first and second 12-h postoperative periods (P = 0.010). The IL1RN*2 carrier group consumed 43% (95% CI, 38-48%) less opioids in the first 24 h after surgery than the IL1RN*1 homozygote group (P = 0.003). Differences in the serum IL-1Ra concentration among the three genotype groups were statistically significant at 24 h postoperatively (P = 0.003), with IL1RN*2 carriers having the highest serum IL-1Ra concentrations. CONCLUSIONS The variable number of tandem repeats in intron 2 of IL1RN may contribute to interindividual variations in opioid consumption in the first 24 h after surgery. Patients homozygous for the IL1RN*1 allele have lower concentrations of IL-1Ra and require higher doses of opioids postoperatively than patients carrying at least one IL1RN*2 allele.

Diabetic neuropathic pain development in type 2 diabetic mouse model and the prophylactic and therapeutic effects of coenzyme Q10

UNLABELLED The early onset of type 2 diabetes mellitus (DM), driven by increasing obesity, is associated with peripheral neuropathy. Here, we characterize diabetic neuropathic pain in New Zealand obese diabetic mice (NZO/HILtJ) as a polygenic model of obesity with type 2 diabetes and investigate the role of coenzyme Q10 (CoQ10) in the prevention and treatment of diabetic neuropathic pain. Since the overexpression of mitogen-activated protein kinase (MAPK), nuclear factor-κB proteins (NF-Kb), toll-like receptor 4 (TLR4) and downstream cytokines (such as CCL2, CXCL10) are considered important factors contributing to the development of neuropathic pain, the expression of these factors and the inhibitory effects of CoQ10 were evaluated. NZO/HILtJ mice spontaneously developed type 2 DM and increased body mass with diabetic neuropathic pain. CoQ10 treatment decreased pain hypersensitivity and long-term supplementation prevented the development of diabetic neuropathic pain but did not attenuate diabetes. Spinal cord, blood serum, liver tissue, and dorsal root ganglia (DRG) from diabetic mice demonstrated increased lipid peroxidation, which was decreased by CoQ10 treatment. The percentage of positive neurons of p65 (the activated marker of NF-KB) and MAPK in DRG were significantly higher in DM mice compared to controls. However, CoQ10 treatment significantly decreased p65 and MAPK positive neurons in the DRG of DM mice. RT-PCR demonstrated that elevated levels of mRNA of CCL2, CXCL10 or TLR4 in the spinal cord of DM mice decreased significantly when DM mice were treated with CoQ10. CONCLUSION This model may be useful in understanding the mechanisms of neuropathic pain in type 2 DM induced neuropathic pain and may facilitate preclinical testing of therapies. CoQ10 may decrease oxidative stress in the central and peripheral nervous system by acting as an anti-oxidant and free-radical scavenger. These results suggest that CoQ10 might be a reasonable preventative strategy for long-term use and using CoQ10 treatment may be a safe and effective long-term approach in the treatment of diabetic neuropathy.

The impact of CYP2D6 genetic polymorphisms on postoperative morphine consumption.

BACKGROUND Endogenous morphine-like compounds have been identified in humans and are released in response to stress. Human monocytes and granulocytes express the micro opiate receptor, micro3, which is morphine selective but opiate peptide insensitive. Recent studies have shown that CYP2D6 acts at critical steps for endogenous morphine biosynthesis. We theorized that ultrarapid (UM) CYP2D6 metabolizers may have an enhancement of their endogenous pain modulating mechanisms. METHODS After institutional review board approval, a previously developed surgical patient database was evaluated for information concerning CYP2D6 genotypes and morphine consumption. One hundred forty-two patients were found to have adequate information to be included in this current analysis. The study group was divided, based on morphine consumption, into two subgroups: low morphine consumers (LMC) (< or =10 mg/4 h, N = 80) and high morphine consumers (HMC) (>10 mg/4 h, N = 62). DNA was extracted from blood in all patients and was genotyped by the Amplichip (Roche, Pleasanton, CA) to determine the specific CYP2D6 genotypes. RESULTS CYP2D6 UM were found to occur more frequently in the LMC group than in the HMC group (8/80 vs 0/62, P = 0.0091). No significant differences were noted for the poor, intermediate, or extensive metabolizers. CONCLUSIONS Our current results suggest that CYP2D6 UM appear to require less morphine in the acute postoperative period compared with other CYP2D6 metabolizer groups. One possible mechanism for this observation is that CYP2D6 UM may have higher efficiency in synthesizing endogenous morphine compared with other metabolizers, thus increasing endogenous pain modulation and reducing the need for exogenous morphine.

Catechol-o-methyltransferase polymorphisms predict opioid consumption in postoperative pain.

BACKGROUND:Previous studies have associated the catechol-O-methyltransferase (COMT) enzyme rs4680 polymorphism with opioid consumption in the treatment of chronic cancer pain. In this study, we evaluated the association between COMT rs4680 and rs4818 polymorphisms and opioid consumption in the acute postoperative period after a nephrectomy. METHODS:Opioid consumption and pain scores were evaluated in 152 patients for 48 hours after nephrectomy. The genotype of each patient was determined using polymerase chain reaction on DNA extracted from blood samples. The association between rs4680 and rs4818 genotypes and opioid consumption was evaluated using general linear model regression analysis. All P values and confidence intervals were Bonferroni corrected for the 3 comparisons among genotypes. RESULTS:In the 24-hour period after surgery (COMT rs4680), patients homozygous for the variant Val/Val consumed 36% (95% confidence interval, 31%–41%) more opioids than patients homozygous for the Met/Met group (P = 0.009). No statistically significant differences among the 3 genotype groups were noted for pain scores or emesis medication use in the first 24 hours after surgery. There was a statistically significant increase in emesis medication use in patients possessing the CC genotype of rs4818 when compared to patients carrying the GG genotypes (P = 0.035). In the 6- to 48-hour postsurgery period, there was significantly higher opioid consumption in the high-activity homozygotes Val/Val than in the homozygous Met/Met group for COMT rs4680 (0–6 h: P = 0.005; 0–12 h: P = 0.015; 0–24 h: P = 0.015; and 0–48 h: P = 0.023). Patients in the homozygous GG group COMT rs4818 single nucleotide polymorphism showed statistically significant differences in opioid consumption in the first 6 hours after nephrectomy compared with heterozygous CG patients (P = 0.02). CONCLUSIONS:The genetic variant of the COMT rs4680 single nucleotide polymorphism is associated with variability in opioid consumption in postoperative nephrectomy patients. The COMT rs4818 polymorphism may prove useful in predicting emesis medication use postoperatively.

Single-Nucleotide Polymorphism C3435T in the ABCB1 Gene is Associated with Opioid Consumption in Postoperative Pain

BACKGROUND ABCB1 is a major determinant of opioid bioavailability; however, no previous studies have provided positive evidence of an association between single-nucleotide polymorphisms (SNPs) of ABCB1 and opioid usage in acute pain management. The aim of this study was to test the association between the functional SNP C3435T in ABCB1 and opioid consumption in postoperative pain in patients undergoing a nephrectomy. Additionally, we explored the association between C3435T and opioid side effect. METHODS C3435T was genotyped in 152 patients undergoing a nephrectomy. Opioid consumption and pain scores were evaluated as well. The effect of genotype on opioid consumption was modeled using a general linear mixed model. RESULT Based on a mixed linear model, the ABCB1 three genotypes showed a statistically significant effect on opioid consumption (F = 4.20, P = 0.017). There was a statistically significant difference in opioid consumption among the ABCB1 three genotypes in the 0-6 hours (P = 0.031, 95% confidence interval [CI] CC 14.7-24.8 mg and TT 5.2-14.6 mg) and 6-12 hours (P = 0.009, 95% CI CC 5.6-13.8 mg and TT 1.2 mg-5.1 mg) postoperative period. There were no significant statistical differences in opioid consumption among the ABCB1 three genotypes in the 12-24 hours (P = 0.302) and 24-48 hours (P = 0.763) postoperative period. The TT genotype had significantly lower levels of cumulative opioid consumption compared with the CC genotype in first 24 hours after surgery (P = 0.029). No statistically significant differences among the three genotype groups were noted for postoperative pain scores or emesis medication use in the first 24 hours after surgery. CONCLUSION Our results demonstrate an association between the ABCB1 polymorphism (C3435T) and interindividual variations in opioid consumption in the acute postoperative period after nephrectomy. The ABCB1 polymorphism may serve as an important factor to guide acute pain therapy in postoperative patients.

A comparison of different types of hazardous material respirators available to anesthesiologists.

OBJECTIVE Despite anesthesiology personnel involvement in initial treatment of patients exposed to potentially lethal agents, less than 40 percent of US anesthesiology training programs conduct training to manage these patients.(1) No previous studies have evaluated performance of anesthesiologists wearing protective gear. The authors compared the performance of anesthesiologists intubating a high-fidelity mannequin while wearing either a powered air-purifying respirator (PAPR) or a negative pressure respirator (NPR). METHODS Twenty participants practiced intubations on a high-fidelity simulator until comfortable. Each subject performed 10 repetitions, initially without any gear, then while wearing a protective suit, gloves, and respirator. The order of gear use was randomized and all subjects used both devices. Time for task completion were recorded, and at the end of the trial, subjects were asked to rate their comfort with the equipment. RESULTS After controlling for other variables, overall statistically slower total performance times were observed with use of the PAPR when compared to the control arm and use of the NPR (p 5 0.01 and p < 0.007, respectively). Of the total 90 intubations, only one proved to be esophageal and initially undetected. CONCLUSIONS The use of an NPR or PAPR does not preclude an anesthesiologist from successfully intubating, but practice is necessary. The slightly better performance with the NPR is weighed against the improved comfort of the PAPR and the fact that PAPR users could wear eyeglasses. Neither type of gear allowed the users to auscultate the lung fields to confirm correct endotracheal tube placement.

The effect of needle bevel position on pain for subcutaneous lidocaine injection.

It is a common practice for medical practitioners to use subcutaneous infiltration of lidocaine to alleviate the pain of intravenous cannulation or line insertion. Although previous studies have assessed several factors affecting the pain associated with local anesthetic infiltration, there is a paucity of data on the effects of needle bevel position. In this prospective, randomized, controlled trial, we compared the effect of two different needle bevel positions (bevel up versus bevel down) and the pain associated with the subcutaneous injection of 1% lidocaine in 50 adult volunteers. Significantly higher pain scores were observed when the needle was placed bevel down compared with bevel up (P = .02). No significant differences in pain scores were noted between the groups for age and gender.

Acute Hypoglycemia Induces Painful Neuropathy and the Treatment of Coenzyme Q10

Diabetic neuropathic pain is reduced with tight glycemic control. However, strict control increases the risk of hypoglycemic episodes, which are themselves linked to painful neuropathy. This study explored the effects of hypoglycemia-related painful neuropathy. Pretreatment with coenzyme Q10 (CoQ10) was performed to explore the preventive effect of CoQ10 on hypoglycemia-related acute neuropathic pain. Two strains of mice were used and 1 unit/kg of insulin was given to induce hypoglycemia. Mechanical sensitivity of hindpaw withdrawal thresholds was measured using von Frey filaments. Blood glucose levels were clamped at normal levels by joint insulin and glucose injection to test whether insulin itself induced hypersensitivity. Results suggest that the increased mechanical sensitivity after insulin injection is related to decreased blood glucose levels. When blood glucose levels remained at a normal level by the linked administration of insulin and glucose, mice demonstrated no significant change in mechanical sensitivity. Pretreatment with CoQ10 prevented neuropathic pain and the expression of the stress factor c-Fos. These results support the concept that pain in the diabetic scenario can be the result of hypoglycemia and not insulin itself. Additionally, pretreatment with CoQ10 may be a potent preventive method for the development of neuropathic pain.