Prevalence and clinical correlates of vitamin D inadequacy among patients with chronic pain.

OBJECTIVE: Vitamin D inadequacy is associated with medication refractory musculoskeletal pain and neuromuscular dysfunction. This vitamin deficiency could subsist as an unrecognized comorbid condition among patients with chronic pain. The primary objective of this study was to determine the prevalence and clinical correlates of vitamin D inadequacy in patients seeking treatment for chronic pain. DESIGN: Retrospective case series. SETTING: Multidisciplinary pain rehabilitation center at a tertiary referral medical center. PATIENTS: The study involved 267 chronic pain patients admitted from February to December 2006. INTERVENTION: Serum 25-hydroxyvitamin D (25[OH]D) was drawn at admission. OUTCOME MEASURES: Patients with serum 25[OH]D levels < or=20 ng/mL were considered to have inadequate levels and those with levels >20 ng/mL were considered to have adequate levels. Upon admission, opioid intake was documented and patients completed the Short Form-36 Health Status Questionnaire. RESULTS: The prevalence of vitamin D inadequacy was 26% (95% confidence interval, 20.6-31.1%). Among patients using opioids, the mean morphine equivalent dose for the inadequate vitamin D group was 133.5 mg/day compared with 70.0 mg/day for the adequate group (P = 0.001). The mean duration of opioid use for the inadequate and adequate groups were 71.1 months and 43.8 months, respectively (P = 0.023). Opioid users with inadequate levels reported worse physical functioning (P = 0.041) and health perception (P = 0.003) than opioid users with adequate levels. CONCLUSION: The prevalence and clinical correlates identified in this pilot study provide the basis for the assertion that vitamin D inadequacy may represent an under-recognized source of nociception and impaired neuromuscular functioning among patients with chronic pain.

Web-based learning versus standardized patients for teaching clinical diagnosis: a randomized, controlled, crossover trial.

BACKGROUND: Little evidence exists to guide the selection of methods for teaching clinical diagnosis. PURPOSE: To compare the efficacy, student preference, and cost of a Web-based (WB) program versus a standardized patient (SP) encounter for teaching clinical diagnosis skills to 2nd-year medical students. METHODS: Randomized, controlled, crossover study comparing WB versus SP-based teaching for the clinical diagnosis of abdominal pain and headache. Outcome measures were performance on a 2-case SP examination (scored on the basis of a checklist completed by a faculty observer and an objective score on a postencounter subjective-objective assessment plan [SOAP] note), format preferences as assessed by end-of-course evaluations, and cost. RESULTS: Thirty students consented to participate. WB and SP training produced similar scores on both the Abdominal Pain checklist (66% vs. 62%; p = .17) and Headache checklist (56% vs. 63%; p = .07). WB training produced a higher score on the Abdominal Pain SOAP note (69% vs. 47%; p = .006), but not the Headache SOAP note (69% vs. 67%; p = .85). Students rated the SP format higher than the WB format on all 7 preference measures. Start-up costs were estimated at 2,190 dollars for the SP format and 2,250 dollars for the WB format. Ongoing costs per case per student were estimated to be 45 dollars for the SP format and 30 dollars for the WB format. CONCLUSIONS: WB and SP learning outcomes were comparable, but students preferred the SP format. Start-up costs were comparable, but the ongoing costs of the WB format were less expensive, suggesting that WB teaching may be a viable strategy.

Principal component analysis of nonlinear chromatography.

Principal component analysis (PCA) has been used for the modeling of nonlinear chromatography under overload conditions. A 10-fold range of crude erythromycin samples were loaded onto columns with different stationary-phase chemistries (2 polystyrene, 1 methacrylate) in direct proportion to the bed volumes. The elution profiles indicated slightly concave isotherms for the polystyrene supports and a convex Langmuirian isotherm for the methacrylic support used. The principal component models accounted for over 98% of the original variance in the data for all three columns and were able to give excellent models of complete chromatograms in the absence of first-principle models or physicochemical data. Correlations between sample mass and the principal component scores were made for each that were consistent for the column types despite the different geometries and stationary phases. Linear relationships with high correlation coefficients were observed when the scores of the same principal component were compared between columns. Such correlations offer considerable potential for modeling of nonlinear chromatography.

Mechanical stability of immobilized biocatalysts (CLECs) in dilute agitated suspensions.

Cross-linked enzyme crystals (CLECs) are a novel form of immobilized biocatalyst designed for application in industrial biotransformation processes. In this work we have investigated the mechanical stability of agitated CLEC suspensions in relation to the design and scale-up of bioconversions carried out in stirred-tank reactors. By careful control of the crystallization conditions yeast alcohol dehydrogenase I (YADHI) microcrystals of different size were first prepared having either an hexagonal (approximately 12 microm) or rod-shaped (approximately 4.6 microm) morphology. These were then cross-linked with glutaraldehyde to form CLECs. The rate of breakage of the CLEC suspensions was subsequently measured in a rotating disk shear device (total volume, 11 mL) by monitoring the change in crystal size distribution with time. This device is designed to mimic the shear and energy dissipation rates found in a range of process scale equipment and may be used to study the mechanical stability of any immobilized biocatalyst preparation. Experiments were performed as a function of the speed and duration of disk rotation, CLEC concentration (0.26-2.5 mg.mL(-1)) and energy dissipation rate (2.2 x 10(3) to 6.8 x 10(5) W.kg(-1)). No breakage of the rod-shaped CLECs was observed over the entire range of experimental conditions investigated. Breakage of the larger hexagonal-shaped CLECs did occur, however, at energy dissipation rates, epsilon(max), above 1.0 x 10(5) W.kg(-1), where the calculated length scale of turbulence was around 2.0 microm. Based on visual observation of the sheared CLEC suspensions and models of crystal breakage, it was concluded that breakage of the hexagonal-shaped CLECs occurred due to shear induced attrition. Measurement of the catalytic activity of both the hexagonal and rod-shaped CLECs showed no significant change in activity before and after shearing.