Mat Group Research Articles

Experimental malignancy in the rat induces early hypersensitivity indicative of neuritis

Cancer pain mechanisms involve multiple factors including the accompanying inflammatory process neural effects. Inflammation along a nerve trunk (neuritis) has been shown to induce hypersensitivity at the innervated target organ. In this experiment the neural effects of MAT B mammary adenocarcinoma cells implanted adjacent to sciatic nerve (MAT group) were compared to those induced by thymus cell extract (THY), saline (SAL) and the potent proinflammatory agent Complete Freund's adjuvant (CFA). Significant pain behavior was detected only in the ipsilateral hindpaw of MAT and CFA rats lasting seven days post-operatively (dpo). On the ninth dpo MAT rats developed significant hyposensitivity to mechanical and electrical stimuli. Interleukin (IL)-6 levels (ELISA) from MAT and CFA exposed nerves were significantly elevated at dpo 2 and remained so in MAT at dpo 8. Indomethacin (1 mg/kg i.p.) abolished the observed pain responses in MAT and CFA rats exposed nerves. Light microscopy of the MAT nerves at the second dpo revealed neural infiltration of immune and malignant cells with mild edema. By the seventh dpo there was nerve damage and at dpo 14 nerve tissue was largely replaced by malignant and immune cells. Electrophysiology of saphenous nerves exposed to MAT, CFA or SAL revealed significantly increased spontaneous activity in MAT and CFA groups. Spike response to hindpaw mechanical stimulation was significantly reduced only in the MAT group (dpo 6–9) suggestive of nerve damage. Inflammatory neuritis is an early expression of malignancy and may play a role in chronic cancer-related pain initiation and additionally may offer diagnostic opportunities.

Comparison of Abdominal Muscle Strength Following Ball and Mat Exercise Regimens: A Pilot Study

Purpose: The purposes of this study were a) to verify test-retest experimental design reliability for trunk flexion using the Biodex™ isokinetic dynamometer and b) to compare the strength gain in abdominal muscles during traditional sit-up exercises with the gain during sit-up exercises performed on an exercise ball. Subjects: Twenty-six healthy subjects with no prior history of low back pain participated in this study. Methods: The control group (females=3 males=3) abstained from any exercise. The mat group (females=7 males=3) performed traditional sit-ups on a mat beginning with a scapula lift and advancing to a full sit-up as strength increased. The ball group (females=7 males=3) performed sit-ups seated on a ball, beginning with a backward lean to 45 and advancing to a horizontal trunk position. Both exercise groups performed 6 sets of 10 repetitions during each session 3 x week x 3 weeks. Strength was measured prior to and following the 3 week exercise program with the Biodex™ isokinetic back testing unit at 60°/sec and 120°/sec using a test-retest protocol. Analyses and Results: A Pearson correlation coefficient performed on the test-retest data achieved significance, r =.95. A 3-way ANOVA with repeated measures revealed a significant difference between pre-test and post-test values for all groups (109.3 vs 114.4 ft/lb, p<.02) at 60°/sec. The control group pre-test and post-test values (131.3 and 133.6 ft/lb) showed no change. An interaction effect between speeds and groups was significant (p<.0004) with an increase at 60°/sec (108.4 vs 117 ft/lb) but no change at 120°/sec. Increases for the ball, mat, and control groups at 60°/sec were 12.5, 8.6, and 2.3 ft/lbs, respectively. These increases were not significant. Conclusions: Based on these findings, we conclude that the testing method was reliable and both mat and ball exercises can improve abdominal strength. Although the ball exercises produced the largest strength gain, testing with a larger sample will be necessary to establish a clear advantage for this technique.

Chronic stress induces sensitization in sympathoadrenal responses to stress in borderline hypertensive rats.

The effects of acute foot shock on cardiovascular and sympathoadrenal responses were investigated in chronically stressed borderline hypertensive rats (BHR) and Wistar-Kyoto (WKY) rats. Male BHRs were divided into two groups; the maturation group (Mat) was not stressed, whereas the chronic stress group (AJS) received 8 wk (5 days/wk, 30 min/day) of air-jet stress coupled with immobilization. After chronic stress, the rats were cannulated in the femoral artery and jugular vein. Resting mean arterial pressure (MAP), heart rate (HR), and plasma norepinephrine (NE) levels were higher in the AJS group. In contrast, chronic stress failed to increase basal arterial pressure or HR in WKY rats. In response to acute foot shock, the Mat group had higher MAP increases, at which they plateaued, whereas the AJS rats displayed a progressive decline in MAP. This was associated with higher plasma NE and epinephrine levels but a smaller increase in adrenocorticotropic hormone in AJS versus Mat rats. This hyperactivity in the sympathoadrenal system of chronically stressed BHRs may, in part, account for their mild hypertension.