Biventricular differences in ß-adrenergic receptor signaling following burn injury.

Burn injury detrimentally affects the myocardium, primarily due to over-activation of ß-adrenergic receptors (ß-AR). Autopsy reports from our institution reveal that patients often suffer from right ventricle (RV) failure. Since burn injury affects ß-AR signaling in the left ventricle (LV), we proposed that ß-AR signaling may also be altered in the RV. A rodent model with a scald burn of 60% of the total body surface area was used to test this hypothesis. Ventricles were isolated 7 days post-burn. We examined the expression of ß-ARs via Western blotting and the mRNA expression of downstream signaling proteins via qRT-PCR. Cyclic adenosine monophosphate (cAMP) production and protein kinase A (PKA) activity were measured in membrane and cytosolic fractions, respectively, using enzyme immunoassay kits. ß1-AR protein expression was significantly increased in the RV following burn injury compared to non-burned RV but not in the LV (p = 0.0022). In contrast, ß2-AR expression was unaltered among the groups while Gαi expression was significantly higher in the LV post-burn (p = 0.023). B-arrestin-1 and G-protein coupled receptor kinase-2 mRNA expression were significantly increased in the left ventricle post-burn (p = 0.001, p<0.0001, respectively). cAMP production and PKA activity were significantly lower in the LV post-burn (p = 0.0063, 0.0042, respectively). These data indicate that burn injury affects the ß-AR signaling pathway in the RV independently of the LV. Additionally, non-canonical ß-AR signaling may be activated in the RV as cAMP production and PKA activity were unchanged despite changes in ß1-AR protein expression.

Long-term effects of physical exercise during rehabilitation in patients with severe burns.

BACKGROUND: We have reported that a 12-week exercise program is beneficial for the exercise performance of severely burned children. It is not known, however, whether the beneficial effects remain at 2 years postburn. METHODS: Severely burned children who received no long-term anabolic drugs were consented to this Institutional Review Board-approved study. Patients chose between a voluntary exercise program (EX-group) and no exercise (NoEX-group) after discharge from the acute burn unit. Peak torque per lean leg mass, maximal oxygen consumption, and percent predicted peak heart rate were assessed. In addition, body mass index percentile and lean body mass index were recorded. Both groups were compared for up to 2 years postburn using mixed multiple analysis of variance. RESULTS: A total of 125 patients with a mean age of 12 ± 4 years were analyzed. Demographics between the EX-group (N = 82) and NoEX-group (N = 43) were comparable. In the EX-group, peak torque per lean leg mass, percent predicted peak heart rate, and maximal oxygen consumption increased significantly with exercise (P < .01). Between discharge and 12-24 months, body mass index percentile increased significantly in the EX-Group (P < .05) but did not change in the NoEX-group. There were no significant differences between groups in body mass index percentile, lean body mass index, peak torque per lean leg mass, and maximal oxygen consumption at 24 months postburn. CONCLUSION: Exercise significantly improves the physical performance of burned children. The benefits are limited to early time points, however, and greatly narrow with further recovery time. Continued participation in exercise activities or a maintenance exercise program is recommended for exercise-induced adaptations to continue.

Anatomy of the Vascularized Lateral Femoral Condyle Flap.

BACKGROUND: The perforators of the free lateral femoral condyle flap have yet to be adequately described in humans. Therefore, the authors investigated the perforator vessels of the lateral femoral condyle flap in an anatomical study and discussed potential clinical applications with a particular interest in its indication with vascularized bone and/or iliotibial band for tendon repair surgery. METHODS: The authors dissected thighs of 28 cadavers to evaluate the anatomical properties of perforator vessels that branch from the superior lateral genicular artery and supply bone, cartilage, subcutaneous tissue, and the iliotibial band of the lateral femoral condyle. RESULTS: In each dissected thigh, the superior lateral genicular artery was present and the average pedicle length was 38 ± 10 mm. The average diameter of the superior lateral genicular artery, proximal to its distribution into the deep articular and superficial patellar branches, was 2 ± 0.5 mm. A communication between deep articular and superficial patellar branches was seen in 96 percent of the dissected thighs. In 24 cases (86 percent), the authors were able to show the iliotibial band perforating vessel and harvest a free lateral femoral condyle flap as an osteochondral fasciocutaneous bone flap with vascularized tendon. CONCLUSIONS: Altogether, the authors' results indicate that the blood supply of the lateral femoral condyle flap is consistent and the lateral femoral condyle flap could serve as a free composite flap for complex indications in hand or limb reconstructive surgery. Clinical studies to compare the lateral femoral condyle to other well-established microsurgical free flaps are warranted.