Biomechanical and structural parameters of tendons in rats subjected to swimming exercise.

The aim of this study was to evaluate the effect of swimming exercise, without overloading, on the biomechanical parameters of the calcaneal tendon of rats. 27 male Wistar rats (70 days) were distributed randomly into 2 groups, Control Group (CG; n=15) with restricted movements inside the cage and Swimming Group (SG; n=12), subjected to exercise training in a tank with a water temperature of 30±1°C, for 1 h/day, 5 days/week for 8 weeks. All animals were kept in a reversed light/dark cycle of 12 h with access to food and water ad libitum. After that, they were anesthetized and had their calcaneus tendons collected from their left rear paws. The tendon was submitted to a mechanical test on a conventional test machine. From the stress vs. strain curve, the biomechanical data were analyzed. For the statistical analysis, the Student-T test was used (p<0.05). Of the variables examined, the maximum tension (p=0.009), maximum force (p=0.03), energy of deformation/tendon cross sectional area (p=0.017) and elastic modulus of the tendon (p=0.013) showed positive outcomes in SG. There was no difference in the other parameters. The results indicate that the swimming exercise training, without overloading, was an important stimulus for improving the biomechanical parameters and structural properties of the calcaneal tendon.

Single sublethal dose of microcystin-LR is responsible for different alterations in biochemical, histological and physiological renal parameters.

Microcystins (MCYSTs) are very stable cyclic peptidic toxins produced by cyanobacteria. Their effects on hepatic tissue have been studied extensively, and they are considered to be a potent hepatotoxin. However, several effects of MCYST on other organs have also been described, but generally in studies using higher doses of MCYST. In the present work, we investigated the effect of a single sublethal dose of MCYST-LR (55 µg/kg) in Wistar rats and analyzed different aspects that influenced renal physiology, including toxin accumulation, excretion, histological morphology, biochemical responses and oxidative damage in the kidney. After 24 h of exposure to MCYST-LR, it was possible to observe an increased glomerular filtration rate (6.28 ± 1.56 vs 2.16 ± 0.48 µl/min per cm(2)) compared with the control group. Increase of interstitial space and collagen deposition corresponded to a fibrotic response to the increased production of reactive oxygen species. The observed decrease of Na(+) reabsorption was due to inhibition of the activity of both Na(+) pumps in proximal tubules cells. We suggested that this modulation is mediated by the effect of MCYST as a phosphatase protein inhibitor that maintains the sustained kinase-mediated regulatory phosphorylation of the ATPases. The observed alteration of Na(+) active transporters lead to damage of renal function, since are involved in regulation of water and solute reabsorption in proximal tubules. The results of this report reinforce the importance of understanding the molecular effects of a single sublethal dose of MCYST-LR, which, in this study, was responsible for macro-alterations found in the renal parenchyma and renal physiology in rats.

[Type I neurofibromatosis presenting as a progressive cervical myelopathy. The first case reported in Kaxinawa Indians]. / Neurofibromatosis tipo I manifestada como mielopatía cervical progresiva. Primer caso descrito entre los indios Kaxinawa.

INTRODUCTION: Type I neurofibromatosis is an autosomal dominant disorder with an estimated prevalence of 1/3,000. Half of the new cases are due to mutations; their penetration is complete in adults and may affect any ethnic group. We describe the first reported case of type I neurofibromatosis in a Kaxinawa Indian from the state of Acre, Brazil, in whom the presenting symptoms were of progressive tetraparesis due to multiple paraspinal neurofibromata. CLINICAL CASE: A 16 year old indigenous Kaxinawa boy presented with progressive myelopathy for the past six months. On neurological examination he had hyperreflexive spastic tetraparesia, predominantly on the right side, with the sensory level at C3/C4, multiple medullary automatisms and respiratory difficulty. He also had diffuse café-au-lait stains, including one particularly prominent one measuring 15 cm on his right buttock. MR of the spine showed many hypo-intense lesions at T1 and hyperintense lesions at T2, which took up contrast and were present at all the conjugation foramens bilaterally. These lesions originated at the roots and were suggestive of neurofibromata. On mediastinal tomography there were several neurofibromata in the mediastinum. The patient had a surgical operation for spinal decompression, with a laminectomy at C1/C2 and removal of the neurofibromata on the spinal cord at C1 and C2. The patient has a sister with multiple café-au-lait stains. CONCLUSIONS: Because of the traditional isolation of the Kaxinawa Indians, with whom contact was made at the beginning of the twentieth century, this first case reported of type I neurofibromatosis may be due to a new mutation which presented as a florid form of the disease with multiple spinal neurofibromata.

[Vascular stroke of the brain stem. Study of 21 cases]. / Acidente vascular de tronco encefálico. Estudo de 21 casos.

A prospective study was designed to follow patients with syndromes of brain stem during 12 months (in 1991-1992). The aim was to correlate clinical and radiologic findings and comparing them with the classical descriptions of brain stem syndromes. Twenty one consecutive patients were admitted at the Hospital de Base do Distrito Federal. The diagnosis and the follow up were carried out by neurological examination and neuroradiologic images: CT (100%), angiography (24%, 5) and MRI (5%, 1). Hypertension and old age were the most important risk factors and hemorrhage at pons with extension to midbrain was the most frequent finding. Coma at admission was associated to a poor outcome. The outcome was defined by the Glasgow Outcome Scale: 28% rated 5, 24% rated 4, 5% rated 3, 28% rated 2 and 14% rated 1. Our results show that the clinical presentation of ischemic strokes and hemorrhages of the brain stem very frequently follow a mixed pattern, which do not conciliate with the classical of these syndromes.