The acute phase of the experimental Chagas' disease in rats induces extensive lesion of the heart sympathetic nerve terminals. Because of evidence indicating the involvement of immune reactions in neuron destruction provoked by Chagas' disease, we tested the effects of depleting the complement system by cobra venom factor upon the sympathetic denervation. The serum hemolytic activity against sensitized sheep erythrocytes ensured the efficacy of the anticomplementary treatment. Glyoxylic acid-induced histofluorescence and electron-microscopic methods allowed the study of the heart noradrenergic nerves. T. cruzi infection caused marked rarefaction of fluorescent nerve terminals at day 10 of infection and the ultrastructural study guaranteed that this rarefaction involved lesion of noradrenergic terminals. The complement depletion failed to prevent this early heart noradrenergic denervation, excluding the participation of complement-mediated lysis as a main mechanism.

Trypanosoma cruzi infection in rats induced early lesion of the heart noradrenergic nerve terminals by a complement-independent mechanism

In addition to neurons, interstitial cells of Cajal (ICC) play an important role in coordinating intestinal motility with a pacemaker function. This study aimed to quantitatively analyze ICC, neurons, and muscular area, the latter to correct for quantitation errors resulting from dilation in case of a megacolon and from the dispersion of ICC that can be attributed to muscular hypertrophy. We analyzed 30 colon samples: ten chagasic megacolon (CM), ten chagasic colons without megacolon (CXM), and ten nonchagasic control patients (NC). We measured the area of muscularis propria and counted the number of neurons of the myenteric plexus in a histological section of an intestinal ring and the number of ICC at the level of the myenteric plexus and circular muscle layer, the latter in a section immunohistochemically stained for CD117. Muscular hypertrophy occurred only in the CM group. Compared to the NC group, we found in the CM group a statistically significant reduction of 80 % in the number of neurons, 60 % in the number of ICC in the myenteric plexus, and 38 % in the area of circular muscle. In the CXM group, these numbers were highly variable, and their reduction, less pronounced. We conclude that the number of ICC is significantly reduced in CM patients, and that this might contribute to the pathophysiology of CM. However, the development of CM requires severe denervation, whereas CXM generally exhibits less than 50 % denervation, favoring the hypothesis that the reduction in ICC number is, in part, a consequence of denervation.

The significantly reduced number of interstitial cells of Cajal in chagasic megacolon (CM) patients might contribute to the pathophysiology of CM.

Due to the introduction of computer technology into manometry laboratories, three-dimensional manometric images of the lower esophageal sphincter can be constructed based on radially oriented pressures, a method termed 'computerized axial manometry.' Calculation of the sphincter pressure vector volume using this method is superior to standard manometric techniques in assessing lower esophageal sphincter function in patients with gastroesophageal reflux disease and idiopathic achalasia. Despite similarities between idiopathic achalasia and chagasic esophagopathy found using clinical, radiological, and manometric studies, controversy around lower esophageal sphincter pressure persists. The goal of this study was to analyze esophageal motor disorders in Chagas' megaesophagus using computerized axial manometry. Twenty patients with chagasic megaesophagus (5 men, 15 women, and average age 50.1 years, range 17-64) were prospectively studied. For three-dimensional imaging construction of the lower esophageal sphincter, a low-complacency perfusion system and an eight-channel manometry probe with four radial channels placed in the same level were used. For probe traction, the continuous pull-through technique was used. Results showed that the lower esophageal sphincter of patients with chagasic megaesophagus have significantly elevated pressure, length, asymmetry, and vector volumes compared to those of normal volunteers (P < 0.05). Aperistalsis of the esophageal body waves was observed in all patients and contraction amplitude was lower than that in normal patients. We conclude that patients with chagasic megaesophagus have hypertonic lower esophageal sphincter and aperistalsis of the esophageal body.

Lower esophageal sphincter analysis using computerized manometry in patients with chagasic megaesophagus

Audiogenic seizures and the pineal gland.

An experimental model embodies an evaluation procedure that helps the investigator to choose between possible alternatives. In this paper, consideration is given to a variety of aspects related to the host-parasite relationship inTrypanosoma cruzi infection and disease. Although several animal species have been used, there is still a lack of consistent experimental studies. A few examples of investigations mainly in dogs, monkeys, and rabbits are briefly described, showing the diversity of methodological approaches and, therefore, the difficulty experienced in comparing results and interpretations. Emphasis was given to the need for a suitable model presenting all possible stage of the infection as seen in man, as well as the functional and organic disorders commonly seen in this disease. The alterations of the autonomic nervous system involving the heart and other organs in Chagas' disease was stressed.

Chagas' heart disease: experimental models.

The authors studied the effect of noise (110 dB), delivered by an eletric bell, upon parenchima cells of pineal gland of albino female rats. Several experimental groups were previously formed and stimulated during, 1, 2, 4 and 7 days. In addition another group was formed and stimulated during 7 days plus 10 additional stimulations of about 3 minutes each after the routine stimulations in the seventh day. The authors observed that a single stimulation of about 3 minutes was sufficient to determine alterations in the parenchima cells of the pineal of experimental animals; the changes were characterized by picnolisis in some groups, whereas in others groups picnolisis and interstitials vacuolizations were evidently increased directly with stimulation. The results suggest that the sound stimulation has a destructible effect upon the parenchima cells of the pineal gland of the female albino rats.

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de Azevedo Ba

Papers

Cellular changes in the pineal body of albino female rats. Effect of daily acoustic simulation