Maria E. Frazer

Triple-transgenic Alzheimer's disease mice exhibit region-specific abnormalities in brain myelination patterns prior to appearance of amyloid and tau pathology.

Alzheimers disease (AD) is a progressively debilitating brain disorder pathologically defined by extracellular amyloid plaques, intraneuronal neurofibrillary tangles, and synaptic disintegrity. AD has not been widely considered a disease of white matter, but more recent evidence suggests the existence of abnormalities in myelination patterns and myelin attrition in AD‐afflicted human brains. Herein, we demonstrate that triple‐transgenic AD (3xTg‐AD) mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock‐in mutation, and tau P301L mutant transgene, exhibit significant region‐specific alterations in myelination patterns and in oligodendrocyte marker expression profiles at time points preceding the appearance of amyloid and tau pathology. These immunohistochemical signatures are coincident with age‐related alterations in axonal and myelin sheath ultrastructure as visualized by comparative electron microscopic examination of 3xTg‐AD and nontransgenic mouse brain tissue. Overall, these findings indicate that 3xTg‐AD mice represent a viable model in which to examine mechanisms underlying AD‐related myelination and neural transmission defects that occur early during presymptomatic stages of the disease process.

Screening for Neuropathic Characteristics in Failed Back Surgery Syndromes: Challenges for Guiding Treatment

OBJECTIVE Neuropathic pain screening tools have shown promise in identifying common neuropathic pain characteristics that derive from diverse etiologies (e.g., diabetic peripheral neuropathy, postherpetic neuralgia). However, no prior studies have specifically assessed whether these tools are capable of discerning the underlying pain mechanisms in the vast, heterogeneous group of patients diagnosed with failed back surgery syndrome (FBSS). DESIGN In this clinical observational study, two tests for neuropathic pain characteristics, the Douleur Neuropathique en 4 (DN4) and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) questionnaires, were performed on 43 subjects with FBSS. Subjects underwent physical or neurosensory exam components of the DN4 and LANSS in the region of most severe pain (e.g., axial low back or lower extremities). DN4 and LANSS scores were correlated with clinical history and neurologic exam, pain-related quality of life questionnaires, and compared to an independent assessment of pain distribution. RESULTS The presence of neuropathic characteristics, determined by the DN4 (62% sensitivity, 44% specificity), LANSS (38% sensitivity, 75% specificity; cut-offs of 4 and 12, respectively), or their combination (20% sensitivity, 58% specificity) was associated with higher pain intensity as measured by the visual analog scale (DN4 > 4, P = 0.001; LANSS ≥ 12, P = 0.042), modified Brief Pain Inventory-Short Form (DN4 > 4, P = 0.001; LANSS ≥ 12, P = 0.082), and Neuropathic Pain Symptom Inventory (DN4 > 4, P = 0.001; LANSS ≥ 12, P = 0.001), and greater pain-related functional impairment as measured by the Roland-Morris Disability Questionnaire (DN4 > 4, P = 0.006; LANSS ≥ 12, P = 0.018). The percentage of subjects characterized as neuropathic by the DN4 and LANSS lacked concordance (67.4 vs. 25.6), and the distribution of most severe symptoms (i.e., axial vs radicular) did not correlate with subjects determined to have neuropathic pain. CONCLUSIONS Unlike other neuropathic syndromes, the neuropathic component of FBSS is less reliably identified by the LANSS and DN4.

Double-blind, randomized, controlled, crossover trial of pregabalin for neurogenic claudication

Objectives: To test the effects of pregabalin on the induction of neurogenic claudication. Methods: This study was a randomized, double-blind, active placebo-controlled, 2-period, crossover trial. Twenty-nine subjects were randomized to receive pregabalin followed by active placebo (i.e., diphenhydramine) or active placebo followed by pregabalin. Each treatment period lasted 10 days, including a 2-step titration. Periods were separated by a 10-day washout period, including a 3-day taper phase after the first period. The primary outcome variable was the time to first moderate pain symptom (Numeric Rating Scale score ≥4) during a 15-minute treadmill test (Tfirst). Secondary outcome measures included pain intensity at rest, pain intensity at the end of the treadmill test, distance walked, and validated self-report measures of pain and functional limitation including the Roland-Morris Disability Questionnaire, modified Brief Pain Inventory–Short Form, Oswestry Disability Index, and Swiss Spinal Stenosis Questionnaire. Results: No significant difference was found between pregabalin and active placebo for the time to first moderate pain symptom (difference in median Tfirst = −1.08 [95% confidence interval −2.25 to 0.08], p = 0.61). In addition, none of the secondary outcome measures of pain or functional limitation were significantly improved by pregabalin compared with active placebo. Conclusions: Pregabalin was not more effective than active placebo in reducing painful symptoms or functional limitations in patients with neurogenic claudication associated with lumbar spinal stenosis. Classification of evidence: This study provides Class I evidence that for patients with neurogenic claudication, compared with diphenhydramine, pregabalin does not increase the time to moderate pain during a treadmill test.

A Randomized, Double-blind, Placebo-Controlled Crossover Trial of Oxymorphone Hydrochloride and Propoxyphene/Acetaminophen Combination for the Treatment of Neurogenic Claudication Associated With Lumbar Spinal Stenosis

Study Design. Randomized, double-blind, placebo-controlled, single-dose crossover study. Objective. To test the analgesic efficacy of oxymorphone hydrochloride (OH) and propoxyphene/acetaminophen (PA) for patients with neurogenic claudication associated with lumbar spinal stenosis. Summary of Background Data. Although opioids are often prescribed for neurogenic claudication, no randomized controlled studies support their efficacy for this condition. Patients with neurogenic claudication are generally excluded from clinical trials or included with patients who have nonspecific chronic low back pain, yielding a heterogeneous study population with very different pathophysiologies and clinical presentations. Methods. Participants received a single dose of each of the 3 treatments in random order. Treatments were separated by at least 3-day washout periods. The primary outcome variable was the time to first treadmill walking–induced moderate pain (≥4 out of 10 on a Numeric Rating Scale) (Tfirst) assessed 90 minutes after treatment administration. Secondary outcome measures included patient global assessment of low back pain, Roland-Morris Disability Questionnaire, Modified Brief Pain Inventory-Short Form, Oswestry Disability Index, and Swiss Spinal Stenosis Questionnaire. Results. The study was prematurely terminated because of the removal of PA from the US market. Twenty-four patients were randomized; 21 completed all 3 treatment periods. There were no significant differences among the treatment groups with respect to the median Tfirst (OH—placebo: median [98.3% confidence limits] =−0.25 min [−6.54, 5.00]; PA—placebo: 0.02 min [−7.65, 4.90]; OH—PA: −0.27 min [−5.56, 6.66]). Conclusion This trial failed to demonstrate a benefit of OH or PA in patients experiencing neurogenic claudication. Considering the potential negative side effects of chronic opioid use, additional research is necessary to evaluate the efficacy of sustained opioid treatment specifically for neurogenic claudication. Level of Evidence: 2

Evaluation of outcome measures for neurogenic claudication A patient-centered approach

Objectives: To determine whether patients with neurogenic claudication associated with lumbar spinal stenosis would prefer a treatment that makes it possible for them to walk farther or walk with less pain; to examine associations between this treatment preference and patient-reported and in-clinic treadmill testing measures of walking ability and walking-associated pain. Methods: In this cross-sectional study, 269 patients with neurogenic claudication were asked to report their pain intensity when walking, complete the Swiss Spinal Stenosis Questionnaire, rank their outcome preferences for treatment, and undergo standardized treadmill testing, including measures of final pain rating and time to first pain of moderate intensity (Tfirst). Descriptive statistics were used to characterize patient preferences for treatment outcome. Associations between self-report questionnaires and standardized treadmill testing outcomes were evaluated using Spearman correlations. Results: Seventy-nine percent of patients expressed a preference for treatment that allowed them to walk with less pain. Preference for reduced pain was associated with higher pain during daily walking, along with a shorter Tfirst and higher final pain severity on treadmill testing. In contrast, patient preference for treatment outcome was not associated with self-reported measures of daily walking capacity or walking distance on the treadmill. Conclusions: A majority of patients with neurogenic claudication prioritized walking with reduced pain over walking farther. Reduction in pain while walking may therefore constitute a sufficient patient-focused treatment outcome for the majority of these patients. These results have implications for clinical trial design and assessment of treatment efficacy in neurogenic claudication.

Interpretation of Urine Drug Testing Results in Patients Using Transdermal Buprenorphine Preparations for the Treatment of Chronic Noncancer Pain

OBJECTIVE To determine whether the prevailing liquid chromatography and tandem mass spectroscopy assay (LC-MS/MS) assay designed to monitor buprenorphine compliance of the sublingual formulation used in the substance abuse treatment setting can be extrapolated to the transdermal formulation used in the chronic pain treatment setting, which is 1000-fold less concentrated. DESIGN Retrospective chart review. SUBJECTS Self-reported compliant patients using the transdermal or sublingual formulations of buprenorhphine. Transdermal patch application was also visually confirmed during clinic visits. METHODS Urine drug test results from a LC-MS/MS were compared between samples from transdermal and sublingual patients. RESULTS While all sublingual patients tested positive for at least one metabolite of buprenorphine, only 69% of the transdermal patients did so. In addition, the most abundant metabolite in the transdermal patients was buprenorphine-glucuronide, as compared with norbuprenorphine-glucuronide in sublingual patients. CONCLUSIONS These data suggest that currently available urine drug tests for buprenorphine, including the more expensive LC-MS/MS based assays, may not be sufficiently sensitive to detect the metabolites from transdermal buprenorphine patients. This study highlights the need to evaluate the value and sensitivity of urine drug tests given the wide range of buprenorphine dosing in clinical practice. These results underscore the need for additional cost benefit analyses comparing different confirmatory drug testing techniques including many commercially available drug testing options.

(115) Interpretation of urine drug testing results in patients using transdermal buprenorphine preparations for the treatment of chronic non-cancer pain

Objective. To determine whether the prevailing liquid chromatography and tandem mass spectroscopy assay (LC-MS/MS) assay designed to monitor buprenorphine compliance of the sublingual formulation used in the substance abuse treatment setting can be extrapolated to the transdermal formulation used in the chronic pain treatment setting, which is 1000-fold less concentrated. Design. Retrospective chart review. Subjects. Self-reported compliant patients using the transdermal or sublingual formulations of buprenorhphine. Transdermal patch application was also visually confirmed during clinic visits. Methods. Urine drug test results from a LC-MS/MS were compared between samples from transdermal and sublingual patients. Results. While all sublingual patients tested positive for at least one metabolite of buprenorphine, only 69% of the transdermal patients did so. In addition, the most abundant metabolite in the transdermal patients was buprenorphine-glucuronide, as compared with norbuprenorphine-glucuronide in sublingual patients. Conclusions. These data suggest that currently available urine drug tests for buprenorphine, including the more expensive LC-MS/MS based assays, may not be sufficiently sensitive to detect the metabolites from transdermal buprenorphine patients. This study highlights the need to evaluate the value and sensitivity of urine drug tests given the wide range of buprenorphine dosing in clinical practice. These results underscore the need for additional cost benefit analyses comparing different confirmatory drug testing techniques including many commercially available drug testing options. VC 2014 Wiley Periodicals, Inc.

P3-404: Triple-transgenic Alzheimer's disease mice exhibit marked abnormalities in brain myelination patterns prior to appearance of amyloid and tau pathology

locus coeruleus, the same neurons that are lost in Parkinson’s disease (PD). Methods: Human dopaminergic SH-SY5Y neuroblastoma cells have been stably transfected with wild-type (WT) Parkin and the Parkin ARJP mutants G328E and R42P. Co-immunoprecipitation has been used to investigate if Parkin interacts with PLC1 followed by In vitro ubiquitin conjugation assay in order to examine if Parkin can ubiquitylate PLC1. PLC activity was measured by Phosphoinositide hydrolysis assay. Intracellular Ca measurements have been done by using the calcium indicator Fluo-3. Cell viability was determined by the MTT assay. Results: We show that Parkin is associated with Phospholipase C1 ( PLC1) and that this association is impaired in ARJP Parkin mutants, affecting PLC1 ubiquitination. Increased steady state levels of PLC1 were noted in ARJP Parkin mutant cells, and in Parkin knockout mouse brain. Parkin mutants have enhanced basal phosphoinositide hydrolysis and intracellular Ca levels ([Ca ]i). Neomycin (PLC inhibitor) and dantrolene (Ryanodine receptor inhibitor) decreased [Ca ]i in Parkin mutants to those seen in WT Parkin cells, suggesting that differences were a consequence of altered PLC activity. Also, the protection of WT Parkin against 6-hydroxydopamine (6OHDA) toxicity could be mimicked in ARJP mutants by the addition of dantrolene, implying that affecting Ca release from ryanodine-sensitive stores is sufficient to protect neurons from toxicity. Conclusions: Our findings indicate that PLC1 is a substrate for Parkin. We suggest that loss of function in Parkin mutations leads to PLC1 accumulation and to a disruption in downstream signalling that makes cells more vulnerable to neurotoxins such as 6OHDA.