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[This corrects the article DOI: 10.1186/s13030-015-0046-0.].
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BACKGROUND: Most people with rheumatoid arthritis (RA) are physically inactive. An accelerometer worn on the waist has been used to evaluate physical activity in people with chronic conditions. It is useful for evaluating moderate to vigorous activity, although it tends to underestimate light or mild activities such as housework or family duties. An accelerometer worn on the wrist (i.e., actigraph) has recently been used to capture daily physical activity in inactive individuals. The purposes of this study were to investigate physical activity measured by an actigraph in patients with RA and in healthy individuals and to investigate the association between actigraphic data and self-reported physical function. METHODS: The subjects were 20 RA patients and 20 healthy individuals. All participants wore an actigraph on their wrist for 6-7 consecutive days. They also completed the Health Assessment Questionnaire disability index (HAQ-DI) and the Medical Outcomes Study (MOS) 36-item short form health survey (SF-36). We extracted three parameters from the actigraphic data: mean activity count (MAC), peak activity count (PAC), and low activity ratio (LAR). These three parameters were compared between the RA patients and healthy individuals and with the self-reported questionnaires. RESULTS: The MAC was significantly lower and the LAR was significantly higher in RA patients than in healthy individuals. The PAC was not different between the two groups. The LAR was negatively correlated with the MAC for the RA patients and for the healthy individuals. The decrease ratio of the LAR with the increase of the MAC for the RA patients was twice that of the healthy participants. In the RA patients, the LAR was significantly and moderately correlated with the HAQ-DI score and two dimensions of the SF-36 (i.e., "physical functioning" and "bodily pain"). CONCLUSION: Investigation of the proportion of low activity count using an actigraph may be useful to identify characteristics of the physical function in RA patients.
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Amelioration of experimental autoimmune encephalomyelitis (EAE) by blockade of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor, 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(f)quinoxaline (NBQX), has been recently demonstrated [Nat. Med. 6 (2000) 67; Nat. Med. 6 (2000) 62]. However, the mechanisms underlying regulation of the extracellular glutamate concentration in EAE are unclear. To address this, we examined the expression of three distinct Na(+)-dependent glutamate transporters (GLT-1, GLAST and EAAC1) in the spinal cord of the Lewis rat EAE. EAE induced a dramatic increase in EAAC1 protein and mRNA levels, which corresponded closely with the course of neurological symptoms. In contrast, the levels of GLT-1 and GLAST protein were down-regulated in the spinal cord at the peak of disease symptoms, and no recovery was observed after remission. Furthermore, these changes in GLT-1, GLAST and EAAC1 expression were suppressed by treatment with NBQX. These results suggest that AMPA receptor activation precedes the altered expression of glutamate transporters, and that the dysregulation of extracellular glutamate concentration might play a critical role in pathological changes and neuronal dysfunction in EAE.