RESUMO

This study evaluated the technique for meniscal allograft transplantation using allografts preserved in glycerin 98% in rabbits. Euthanasia was performed at 70 days to compare the transplanted (TM1 to TM16) versus the contralateral meniscus (OM1 to OM16). Sixteen menisci, 8 transplanted and 8 contralateral, were submitted to gross examination, histomorphometric analysis for identification and quantification of cellular type, and for quantification and distribution of collagen fibers. A revascularization study was conducted in all of the other samples. Lengths of the OM varied from 0.9 to 1.0 cm and two TM were smaller. All TM were completely attached to the synovial membrane, except for one case that presented partial fixation. Both, TM and OM had similar amounts of chondrocytes, fibroblasts and fibrocytes, and at the horns, chondrocytes were predominant. The collagen fibers in TM were well organized throughout the body, and disorganized at the horns. These fibers in OM were organized. The amounts of collagen type I and III, and the vascularization of the perimeniscal tissue and of the edge were similar in OM and TM. These results demonstrated graft integration and thus this transplantation technique and preservation method may be recommended.

Assuntos

RESUMO

The control of body temperature in Spontaneously Hypertensive Rat (SHR) subjected to exercise in warm environment was investigated. Male SHR and Wistar rats were submitted to moderate exercise in temperate (25°C) and warm (32°C) environments while body and tail skin temperatures, as well as oxygen consumption, were registered. Total time of exercise, workload performed, mechanical efficiency and heat storage were determined. SHR had increased heat production and body temperature at the end of exercise, reduced mechanical efficiency and increased heat storage (p < 0.05). Furthermore, these rats also showed a more intense and faster increase in body temperature during moderate exercise in the warm environment (p < 0.05). The lower mechanical efficiency seen in SHR was closely correlated with their higher body temperature at the point of fatigue in warm environment (p < 0.05). Our results indicate that SHR exhibit significant differences in body temperature control during moderate exercise in warm environment characterized by increased heat production and heat storage during moderate exercise in warm environment. The combination of these responses result in aggravated hyperthermia linked with lower mechanical efficiency. Key PointsThe practice of physical exercise in warm environment has gained importance in recent decades mainly because of the progressive increases in environmental temperature;To the best of our knowledge, these is the first study to analyze body temperature control of SHR during moderate exercise in warm environment;SHR showed increased heat production and heat storage that resulted in higher body temperature at the end of exercise;SHR showed reduced mechanical efficiency;These results demonstrate that when exercising in a warm environment the hypertensive rat exhibit differences in temperature control.

RESUMO

The mechanisms of production, and gross, microscopic and electrocardiograhic findings of surgically-induced complete heart block (CHB) in the adult rat are presented. This is an effective in vivo model for establishing alternative methods to electronic pacemakers and for providing detailed information aimed at replacement, reduction and refinement of the technique. Sternal thoracotomy was employed to identify the epicardial fat pad by the aortic root, used as a landmark for cauterization of the atrioventricular (AV) node. Stable CHB was produced in 60 rats with a 70% survival rate. The best survival rate was observed in 8-week-old animals weighing 221 ± 27.6 g. Heart rate before cauterization was 387 ± 55 bpm, reduced after cauterization to 126 ± 40 bpm in the survival and to 65 ± 19 bpm in the non-survival groups. At 30 days findings were: elevated left ventricular end-diastolic pressure (21 ± 5.4 mmHg, P < 0.05); maximal rate of rise of left ventricular pressure (LVP) during isovolumetric contraction (2192 ± 235 mmHg/s, P < 0.05); maximal rate of decrease of LVP (-1658 ± 191 mmHg/s, P < 0.05); isovolumetric relaxation constant (5.7 ± 0.8 ms, P < 0.05) with wet-to-dry lung-weight ratio (78.1 ± 0.4, P < 0.05); heart weight/body weight (0.6 ± 0.1, P < 0.05); heart volume (1.8 ± 0.3 mL, P < 0.05); longitudinal diameter (20.2 ± 1.91 mm, P < 0.05); and transversal diameter (17.0 ± 1.4 mm, P < 0.05) with supported dilated cardiomyopathy which culminated in chronic heart failure. CHB hearts had increased preload and replacement of myofibrils by collagen. CHB was achieved reproducibly by cauterization of the rat AV node and/or His bundle. This led to electrophysiological, hemodynamic, and structural remodeling, and could be useful in long-term cardiac remodeling assessments and potential therapy development.

RESUMO

Diabetic cardiomyopathy is associated with cardiac muscle remodeling, resulting in myocardial dysfunction, whereas exercise training (ET) is a useful nonpharmacological strategy for the therapy of cardiac diseases. This study tested the effects of low-intensity swimming-training on the structural remodeling of the left ventricle (LV) in growing rats with unmanaged experimental diabetes. Thirty-day-old male Wistar rats were divided into four groups (n=5/group): sedentary-control (SC), exercised-control (EC), sedentary-diabetic (SD), and exercised-diabetic (ED). Swimming-training rats exercised 5 days/week, 90min/day, with a load of 5% BW during 8 weeks. Sections of LV were stained with Periodic acid-Schiff, Sirius Red, and Gomori's reticulin. Seven days and 8 weeks after streptozotocin (STZ) induction (60mgkg(-1) BW), blood glucose (BG) in the diabetic groups (SD=581.40±40.48; ED=558.00±48.89) was greater (p<0.05) than in their controls (SC=88.80±21.70; EC=85.60±11.55). Swimming-training reduced BG by 23mg/dL in the diabetics (p>0.05). The LV of diabetic rats had increased interstitial collagen and reticular fibers on the extracellular matrix and presented glycogen accumulation. More importantly, all these adverse tissue changes induced by STZ were attenuated by ET. Together, these findings support the idea of a beneficial role of exercise in the LV remodeling in rats with unmanaged type-1 diabetes mellitus.

Assuntos