Therapeutic Effect of Dimethyl Dimethoxy Biphenyl Dicarboxylate on Collagen-Induced Arthritis in Rats

Objective:To study the effect of oral administration of dimethyl dimethoxy biphenyl dicarboxylate(DDB) on adjusting angiogeneic/inflammatory mediators and ameliorating the pathology of bones in rats with collagen-induced arthritis(CIA).Methods:Wistar rat model of CIA was set up using bovine collagen type Ⅱ.Fifty rats were divided into five groups randomly:normal,CIA model,DDB treatment,methotrexate(MTX) treatment,and combined DDB+MTX treatment.Ankle joints of rats were imaged with digital X-ray machine to show the destruction of joints.Fore and hind paw and knee joints were removed above the ankle joint then processed for haematoxylin and eosin staining.Plasma levels of vascular endothelial growth factor(VEGF),platelet derived growth factor,interleukin-8(IL-8),IL-4,tumor necrosis factor α(TNF-α),and cyclooxygenase-2(COX-2) were quantified by enzyme-linked immunosorbent assay.Nitric oxide levels were detected by Griess reagent.Results:Compared with the CIA model group,a remarkable reduction in various angiogenic(VEGF and IL-8) and inflammatory mediators(TNF-α,IL-4 and COX-2) after treatment with DDB either alone or combined with MTX(P0.05 or P0.01).Histopathological and X-ray findings were confirmatory to the observed DDB anti-arthritic effect.The DDB-treated group showed amelioration in signs of arthritis which appeared essentially similar to normal.Conclusion:Our data shed light on the therapeutic efficacy of DDB in experimental rheumatoid arthritis(RA) compared with a choice drug(MTX) and it may be offered as a second-line drug in the treatment of RA.     

Effects of hyperglycemia on glucose transporters of the muscle: use of the renal glucose reabsorption inhibitor phlorizin to control glycemia.

Individuals with non-insulin dependent or insulin-dependent diabetes mellitus present insulin resistance in peripheral tissues. This is reflected in a subnormal whole body insulin-dependent glucose utilization, largely dependent on skeletal muscle. Glucose transport across the cell membrane of this tissue is rate limiting in the utilization of the hexose. Therefore, it is possible that a defect exists in insulin-dependent glucose transport in skeletal muscle in diabetic states. This review focuses on two questions: is there a defect at the level of glucose transporters in skeletal muscle of diabetic animal models, and is this a consequence of abnormal insulin or glucose levels? The latter question arises from the fact that these parameters usually vary inversely to each other. Glucose transport into skeletal muscle occurs by two membrane proteins, the GLUT1 and GLUT4 gene products. By subcellular fractionation and Western blotting with isoform-specific antibodies, it was determined that isolated plasma membranes (PM) contain GLUT4 and GLUT1 proteins at a molar ratio of 3.5:1 and that an intracellular fraction (internal membranes; IM) different from sarcoplasmic reticulum contains only GLUT4 transporters. The IM furnishes transporters to the PM in response to insulin. Both transporter isoforms bind cytochalasin B in a D-glucose-protectable fashion. In streptozocin-induced diabetes of the rat with normal fasting insulin levels and marked hyperglycemia, the number of cytochalasin B-binding sites and of GLUT4 proteins diminishes in the PM whereas the GLUT1 proteins increase to a new ratio of about 1.5:1 GLUT4:GLUT1. In the IM, the levels of GLUT4 protein drop, as does the cellular GLUT4 mRNA. To investigate if these changes are associated with hyperglycemia, glucose levels were corrected back to normal values for a 24-h period with sc injections of phlorizin to block proximal tubule glucose reabsorption. This treatment restored cytochalasin B binding, restored GLUT4 and GLUT1 values back to normal levels in the PM, and partly restored cytochalasin B binding but not GLUT4 levels in the IM, consistent with only a partial recovery of GLUT4 mRNA. It is concluded that GLUT4 protein in the PM correlates inversely whereas GLUT1 protein correlates directly with glycemia. It is proposed that the decrease in GLUT4 levels is a protective mechanism, sparing skeletal muscle from gaining glucose and experiencing diabetic complications, albeit at the expense of becoming insulin resistant.(ABSTRACT TRUNCATED AT 400 WORDS)     

Interlaboratory validation of a CD71-based flow cytometric method (Microflow) for the scoring of micronucleated reticulocytes in mouse peripheral blood

An interlaboratory study was performed to validate an anti-CD71/flow cytometry-based technique for enumerating micronucleated reticulocytes (MN-RETs) in mouse peripheral blood. These experiments were designed to address International Workshop on Genotoxicity Test Procedures validation criteria by evaluating the degree of correspondence between MN-RET measurements generated by flow cytometry (FCM) with those obtained using traditional microscopy-based methods. In addition to these cross-methods data, flow cytometric MN-RET measurements for each blood sample were performed at two separate sites in order to evaluate the reproducibility of data between laboratories. In these studies, groups of male CD-1 mice were treated with vehicle (saline or vegetable oil), a negative control (saline or vegetable oil), or four dose levels of five known genotoxicants (clastogens: cyclophosphamide, benzo[a]pyrene, 5-fluorouracil, methotrexate; aneugen: vincristine sulfate). Exposure occurred on 3 consecutive days via intraperitoneal injection, and blood samples were obtained approximately 24 hr after the final treatment. MN-RET frequencies were determined for each sample based on the analysis of 2,000 (microscopy) and 20,000 (FCM) reticulocytes. Regardless of the method utilized, each genotoxic agent was observed to cause statistically significant increases in the frequency of MN-RETs, and each response occurred in a dose-dependent manner. Spearman's correlation coefficient (rs) for FCM versus microscopy-based MN-RET measurements (nine experiments, 252 paired measurements) was 0.740, indicating a high degree of correspondence between methods. The rs value for all flow cytometric MN-RET measurements performed at the two independent sites was 0.857 (n = 248), suggesting that the automated method is highly transferable between laboratories. Additionally, the flow cytometric system offered advantages relative to microscopy-based scoring, including a greater number of cells analyzed, much faster analysis times, and a greater degree of objectivity. Collectively, data presented in this report suggest that the overall performance of mouse peripheral blood micronucleus tests is enhanced by the use of the flow cytometric scoring procedure.     

Influence of the time of day on physical performance in patients with coronary artery disease

The exercise training workload for cardiac patients is determined from the peak heart rate achieved safely during a stress test. Circadian rhythms may play a key role in changing physiological responses to the stress test. Therefore, the purpose of this study was to evaluate the influence of the time of day on cardiopulmonary and metabolic responses in highly trained men with coronary artery disease. A group of 15 patients with coronary artery disease [53.5 (SD 6) years] performed two sessions of graded tests to exhaustion: one session was performed at 10 a.m. and the second at 5 p.m. in randomized order. Treadmill velocity was kept constant at a speed of 4.8 km · h^–1 starting with an elevation of 0% which was increased thereafter by 2.5% every 3 min. At rest the results revealed that only oxygen uptake was significantly lower (P < 0.05) in the morning compared to that observed in the evening [2.9 (SD 0.4) compared to 3.5 (SD 0.5) ml O₂ · kg^–1 · min^–1, respectively]. During exercise, differences due to time of day were found in the variables of maximal oxygen uptake which were significantly higher (P < 0.05) in the evening than in the morning [34.2 (SD 2.6) and 40.8 (SD 2.5) ml O₂ · kg^–1 · min^–1, respectively]. These data indicated that in these well-trained coronary artery disease patients there was a significant time of day effect associated with metabolic responses following stress-testing.     

Exercise- and insulin-stimulated muscle glucose transport: distinct mechanisms of regulation.

In mammals, skeletal muscle is the primary target for the stimulation of glucose transport by a variety of activators. These include the hormone insulin and stimuli which increase energy demand such as exercise, hypoxia, and challenges to the oxidative chain. While it is known that both stimuli rapidly elevate glucose uptake into muscle by signalling the translocation of glucose transporters from intracellular stores to the plasma membrane, there are numerous contrasts between energy stressors and insulin in their mechanisms of glucose transport activation. Exercise and insulin recruit distinct intracellular pools of glucose transporters in skeletal muscle and the maximal effects of contraction and insulin are additive. Activation of phosphatidylinositol 3-kinase (PI3-K) is utilized by insulin to induce glucose transporter translocation, but does not participate in the responses to exercise or hypoxia. These findings suggest that energy stressors utilize different mechanisms from insulin to increase glucose influx; however, how these factors elicit their response is not clear. This review will summarize our current knowledge of these alternative pathways of glucose transport regulation. Emphasis is placed on the use of the mitochondrial uncoupler dinitrophenol to investigate mediators of this alternative signalling pathway in L6 muscle cells, a line used to characterize physiological responses in muscle such as glucose transport.     

Initial validation of the SLEEP-50 questionnaire

Initial psychometric properties of the SLEEP-50 questionnaire, designed to detect sleep disorders as listed in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., Text Revision), were examined. The sample consisted of 377 college students, 246 sleep patients, 32 nightmare sufferers, and 44 healthy volunteers. The internal consistency was high (Cronbach's alpha = .85); test-retest correlations fell between .65 and .89. Principal component analysis with a direct oblimin rotation revealed a factor structure that closely matched the designed structure. Sensitivity and specificity scores were promising for all sleep disorders; the agreement between all clinical diagnoses and SLEEP-50-classifications was substantial (kappa = .77). These initial findings indicate that the SLEEP-50 seems able to detect a variety of sleep disorders. The SLEEP-50 can aid in screening for common sleep disorders in the general population.     

Postural adjustments accompanying fast pointing movements in standing, sitting and lying adults

The present study evaluated the effect of different positions, which varied in the amount of bodily support, on postural control during fast pointing movements. Fourteen adult subjects were studied in standing, various sitting and lying positions. Multiple surface electromyograms (EMGs) of arm, neck, trunk and upper leg muscles and kinematics were recorded during a standard series of unilateral arm movements. Two additional series, consisting of bilateral arm movements and unilateral arm movements with an additional weight, were performed to assess whether additional task-load affected postural adjustments differently in a sitting and standing position. Two pointing strategies were used – despite identical instructions. Seven subjects showed an elbow extension throughout the movements. They used the deltoid (DE) as the prime mover (DE group). The other seven subjects performed the movement with a slight elbow flexion and used the biceps brachii (BB) as the prime mover (BB group). The two strategies had a differential effect on the postural adjustments: postural activity was less and substantially later in the BB-group than in the DE group. Anticipatory postural muscle activity was only present in the DE group during stance. In all positions and task-load conditions the dorsal postural muscles were activated before their ventral antagonists. The activation rate, the timing and – to a lesser extent – the amplitude of the dorsal muscle activity was position dependent. The position dependency was mainly found in the caudally located lumbar extensor (LE) and hamstrings (HAM) muscles. The EMG amplitude of LE and HAM was also affected by body geometry (trunk and pelvis position). Position and body geometry had only a minor effect on the activity of the neck and thoracic extensor muscles. This difference in behaviour of lower and upper postural muscles suggests that they could serve different postural tasks: the lower muscles being more involved in keeping the centre of mass within the limits of the support surface, and the upper ones in counteracting the reaction forces generated by movement onset. Increasing task-load by performing bilateral movements and – to a minor extent – during loaded unilateral movements affected the temporal and quantitative characteristics of the postural adjustments during standing and sitting in a similar way. The effect was present mainly during the early part of the response (within 100 ms after prime mover onset). This suggests that feedforward or anticipatory mechanisms play a major role in the task-specific modulation of postural adjustments. Received: 9 April 1997 / Accepted: 9 October 1997     

The free cytoplasmic Ca2+ levels in Duchenne muscular dystrophy lymphocytes

An increased cellular Ca2+ content has been associated with Duchenne muscular dystrophy (DMD). However, estimates of the free cytoplasmic Ca2+ concentration ([Ca2+]i) in cells of DMD patients were not available. We compared the [Ca2+]i levels of normal and DMD peripheral blood lymphocytes and Epstein-Barr virus-transformed lymphoblasts using the novel probe, quin 2, an internally trapped fluorescent indicator. The [Ca2+]i levels of normal and DMD cells were not significantly different.