Evaluation of the new flexible contour backrest for wheelchairs

A new flexible contour backrest for wheelchairs was designed with the objectives of offering adequate posture, uniform pressure distribution, and comfort to the users while keeping the advantages of conventional sling backrests, such as easy to fold, light weight, unobtrusive, and airy. The purpose of this study is to compare the new backrest with two commercially available wheelchair backrests, an adjustable-tension (AT) backrest and a back cushion on a rigid support (RS), in terms of pressure distribution, back profile accommodation, and short-term comfort. Evaluations were done with 15 nonimpaired subjects in a static position. It was shown that the new backrest distributes pressure in a more uniform way than the AT and in a way similar to the RS, while giving a better fit to subjects' trunks than other backrests because of its multiple adjustments. Finally, subjects felt that the new backrest is as comfortable as the RS and more comfortable than the AT.     

The effects of melatonin on Ca(2+) homeostasis in endothelial cells

The effect of melatonin on the Ca(2+) signaling process in bovine aortic endothelial cells (BAE) and in primary cultured vascular endothelial cells from normotensive Sprague Dawley (SDR) and genetically hypertensive (SHR) rats was investigated using the Ca(2+) indicator Fura-2. Acute applications of melatonin failed to initiate a Ca(2+) response in the three cell types considered. However, preincubating SHR aortic endothelial cells with exposure to melatonin increased the internal Ca(2+) release triggered by bradykinin (BK) and ATP while stimulating the related agonist-evoked Ca(2+) entry. This effect appeared specific for SHR cells, as a similar incubation period failed to alter the Ca(2+) responses in BAE and SDR cells. Because of the known overproduction of free radicals in SHR cells, the effect of melatonin on Ca(2+) signaling was also tested in SDR and BAE cells exposed to the superoxide anion radical. Melatonin reversed the deleterious action of free radicals on Ca(2+) signaling in both cases, suggesting that its stimulatory effect in SHR was linked to its antioxidative properties. Finally, experiments where melatonin was applied between successive BK stimulation periods showed an enhancement of the agonist-evoked Ca(2+) entry in BAE and SDR cells. This effect appeared to be independent of the production of second messengers as no specific binding sites for melatonin, including MT1, MT2 and MT3 receptors, could be detected in BAE cells. We conclude that melatonin improves Ca(2+) signaling in dysfunctional endothelial cells characterized by an overproduction of free radicals while stimulating the agonist-evoked Ca(2+) entry in normal endothelial cells through a mechanism not related to its antioxidative properties.     

Comparison of the biomechanical 3D efficiency of different brace designs for the treatment of scoliosis using a finite element model

The biomechanical influence of thoraco-lumbo-sacral bracing, a commonly employed treatment in scoliosis, is still not fully understood. The aim of this study was to compare the immediate corrections generated by different virtual braces using a patient-specific finite element model (FEM) and to analyze the most influential design factors. The 3D geometry of three patients presenting different types of curves was acquired with a multi-view X-ray technique and surface topography. A personalized FEM of the patients’ trunk and a parametric model of a virtual custom-fit brace were then created. The installation of the braces on the patients was simulated. The influence of 15 design factors on the 3D correction generated by the brace was evaluated following a design of experiments simulation protocol allowing computing the main and two-way interaction effects of the design factors. A total of 12,288 different braces were tested. Results showed a great variability of the braces effectiveness. Of the 15 design factors investigated, according to the 2 modalities chosen for each one, the 5 most influential design factors were the position of the brace opening (posterior vs. anterior), the strap tension, the trochanter extension side, the lordosis design and the rigid shell shape. The position of the brace opening modified the correction mechanism. The trochanter extension position influenced the efficiency of the thoracic and lumbar pads by modifying their lever arm. Increasing the strap tension improved corrections of coronal curves. The lordosis design had an influence in the sagittal plane but not in the coronal plane. This study could help to better understand the brace biomechanics and to rationalize and optimize their design.     

Serum concentrations and clinical effects of atorvastatin in patients taking grapefruit juice daily

AIM

To determine whether customary exposure to grapefruit juice (GFJ) alters serum concentrations, effectiveness, and potential adverse effects of atorvastatin in patients requiring the medication.

METHODS

Patients receiving extended treatment with atorvastatin (10, 20 or 40 mg day⁻¹) at a stable dose received 300 ml day⁻¹ of 100% GFJ for a period of 90 days. One cohort of patients (arm A, n = 60) continued on their current dose of atorvastatin; the second cohort (arm B, n = 70) reduced the daily dose by 50%. Serum atorvastatin, lipid profile, liver functions, and creatine phosphokinase (CPK) were measured at baseline and at 30, 60, and 90 days after starting GFJ.

RESULTS

In Arm A patients, co-ingestion of GFJ significantly elevated serum atorvastatin by 19% to 26% compared with baseline. Changes in lipid profile relative to baseline were negligible. There were no adverse effects on liver function tests or CPK. In arm B patients, serum atorvastatin declined by 12% to 25% compared to baseline, with a small but significant unfavourable effect in serum lipid profile. There were no adverse effects on liver function tests or CPK.

CONCLUSION

In patients on extended stable atorvastatin treatment, addition of daily GFJ in typical quantities slightly elevates serum atorvastatin concentrations, but has no meaningful effect on the serum lipid profile, and causes no detectable adverse liver or muscle effects. Reduction of atorvastatin dosage when moderate amounts of GFJ are co-ingested does not appear to be necessary.     

Serotonin innervation of basal ganglia in monkeys and humans

This review paper summarizes our previous contributions to the study of serotonin (5-hydroxytryptamine; 5-HT) innervation of basal ganglia in human and nonhuman primates under normal conditions. We have visualized the 5-HT neuronal system in squirrel monkey (Saimiri sciureus) and human postmortem materials with antibodies directed against either 5-HT, 5-HT transporter (SERT) or 5-HT synthesizing enzyme tryptophan hydroxylase (TPH). Confocal microscopy was used to compare the distribution of 5-HT and dopamine (DA; tyrosine hydroxylase-immunolabeled) axons in human, while the ultrastructural features of 5-HT axon terminals in monkey subthalamic nucleus were characterized at electron microscopic level. In monkeys and humans, midbrain raphe neurons emit axons that traverse the brainstem via the transtegmental system, ascend within the medial forebrain bundle and reach their targets by coursing along the major output pathways of the basal ganglia. These 5-HT axons arborize in virtually all basal ganglia components with the substantia nigra receiving the densest innervation and the striatum the most heterogeneous one. Although the striatum - the major basal ganglia input structure - appears to be a common termination site for many of 5-HT ascending axons, our results reveal that the widely distributed 5-HT neuronal system can also act directly upon neurons located within the two major output structures of the basal ganglia, namely the internal pallidum and the substantia nigra pars reticulata in monkeys and humans. This system also has a direct access to neurons of the DA nigrostriatal pathway, a finding that underlines the importance of the 5-HT/DA interactions in the physiopathology of basal ganglia.     

Assessment of lumbosacral kyphosis in spondylolisthesis: a computer-assisted reliability study of six measurement techniques

Although recognized as an important aspect in the management of spondylolisthesis, there is no consensus on the most reliable and optimal measure of lumbosacral kyphosis (LSK). Using a custom computer software, four raters evaluated 60 standing lateral radiographs of the lumbosacral spine during two sessions at a 1-week interval. The sample size consisted of 20 normal, 20 low and 20 high grade spondylolisthetic subjects. Six parameters were included for analysis: Boxall’s slip angle, Dubousset’s lumbosacral angle (LSA), the Spinal Deformity Study Group’s (SDSG) LSA, dysplastic SDSG LSA, sagittal rotation (SR), kyphotic Cobb angle (k-Cobb). Intra- and inter-rater reliability for all parameters was assessed using intra-class correlation coefficients (ICC). Correlations between parameters and slip percentage were evaluated with Pearson coefficients. The intra-rater ICC’s for all the parameters ranged between 0.81 and 0.97 and the inter-rater ICC’s were between 0.74 and 0.98. All parameters except sagittal rotation showed a medium to large correlation with slip percentage. Dubousset’s LSA and the k-Cobb showed the largest correlations (r = −0.78 and r = −0.50, respectively). SR was associated with the weakest correlation (r = −0.10). All other parameters had medium correlations with percent slip (r = 0.31–0.43). All measurement techniques provided excellent inter- and intra-rater reliability. Dubousset’s LSA showed the strongest correlation with slip grade. This parameter can be used in the clinical setting with PACS software capabilities to assess LSK. A computer-assisted technique is recommended in order to increase the reliability of the measurement of LSK in spondylolisthesis.     

High hepatitis C virus prevalence and incidence among Canadian intravenous drug users

We used data and leftover samples collected through the SurvUDI network to describe the epidemiology of hepatitis C virus (HCV) infection among injection drug users (IDUs) in Eastern Central Canada. Among the 1380 selected IDUs, having participated twice or more between 1997 and 2003, the overall HCV prevalence rate was 60.4% (95% confidence interval [CI]: 57.7-63.0%). Among the 543 initially uninfected participants, the HCV incidence rate was 27.1 per 100 person-years (95% CI: 23.4-30.9 per 100 person-years). Independent predictors of seroconversion, identified among 359 participants, were age, injecting for a year or less, injecting with a syringe previously used by someone else, injecting most often cocaine, engaging in prostitution, and being recruited in a major urban centre. The HCV epidemic severely affects IDUs in this area. Actions to prevent HCV transmission, such as distribution of sterile injection equipment, have to be reinforced. Special efforts have to be targeted towards starting IDUs.     

Diagnostic value of D-dimer in patients with suspected pulmonary embolism: results from a multicentre outcome study

BACKGROUND: D-dimer tests are used in various diagnostic strategies to exclude pulmonary embolism (PE). However, their role as an exclusionary first-line test is still uncertain, mainly because accuracy of the test varies according to the assay and the studied population. METHODS: The aim of this multicentre study was to evaluate the accuracy of D-dimer testing in patients with suspected PE. Diagnosis of PE was based on pre-test clinical probability (PCP) evaluation and both single-detector spiral CT (CT) and lower limbs compression ultrasonography (CUS). Lung scanning and/or pulmonary angiography was mandatory when CT or CUS was inconclusive and when both CT and CUS were normal in a patient with a high PCP. All patients were followed-up for 3 months, looking for VTE recurrence. D-dimers were collected within 24 h of inclusion and stored in each local hematology unit, to be analyzed at the end of all inclusions; physicians in charge of the patient were blinded to D-dimer results. RESULTS: Three hundred and fifty two patients were included in 4 centres. Prevalence of PE was 38.6%. PCP was low in 82 (23.3%), intermediate in 176 (50%) and high in 94 (26.7%) patients. Sensitivity of D-dimer was 96.3% (95% CI: 93-99) and negative predictive value reached 94.4% (95% CI: 90-99). Five patients with a confirmed PE had a D-dimer level below 500 ng/ml (two patients with a high PCP). Among 258 patients with low or intermediate PCP, 80 (31%) had a negative D-dimer test result; three of them had a false negative result and the number needed to test was 3.3. Among 94 patients with a high PCP, 9 had a negative D-dimer test result; two of them had a false negative result and the number needed to test was 13.5. CONCLUSION: These results confirm that rapid assays used in this study can safely exclude PE in first-line testing only in non-high CP patients.