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The aim of this study was to assess the peripheral and cardiac autonomic system by catecholamine measurements in patients with severe chagasic and nonchagasic heart failure. Fifteen chagasic and 16 nonchagasic patients were enrolled in the study. Plasma venous norepinephrine levels (pg/ml) were 397.26 ± 250.11 for chagasic and 660.05 ± 455.57 for nonchagasic patients (p > 0.05), plasma venous epinephrine levels 215.84 ± 254.04 for chagasic and 106.17 ± 65.90 for nonchagasic patients (p > 0.05), aortic root norepinephrine levels 435.46 ± 306.60 for chagasic and 668.16 ± 512.82 for nonchagasic patients (p > 0.05), aortic root epinephrine levels 300.33 ± 302.69 for chagasic and 199.98 ± 162.88 for nonchagasic patients (p > 0.05), coronary sinus norepinephrine levels 636.10 ± 495.22 for chagasic and 552.17 ± 535.54 for nonchagasic patients (p > 0.05) and coronary sinus epinephrine levels 226.66 ± 277.47 for chagasic and 69.21 ± 35.62 for nonchagasic patients (p = 0.02). Myocardial and peripheral norepinephrine and epinephrine extractions were similar for both groups. Taken together, these findings may suggest that chagasic patients with congestive heart failure have biochemical evidence of cardiac autonomic dysfunction with preservation of the peripheral sympathetic activity.

'Carcinoma of the colon does not occur in cases of megacolon' is an axiom held by Brazilian physicians working in endemic areas for Chagas' disease. The objective of the present study was to test this axiom experimentally by submitting rats with experimental megacolon to a carcinogen which causes carcinoma of the colon. Eighty young male Wistar rats received serosal application of either saline (0.9% NaCl) or 2 mM benzalkonium chloride (BAC) to the distal colon. Ten months later randomly chosen saline and BAC rats were injected weekly with dimethylhydrazine (DMH) for 20 weeks. Non-DMH-treated rats from both original groups were maintained, for a total of four experimental groups. Three months after the injections all surviving rats were killed. At autopsy the presence of absence of carcinomas along the colon was recorded. The induction of megacolon was evaluated by morphometry of the wall from the distal colon and myenteric denervation was assessed by neuron counts. An increase of at least 2-fold in distal colon wall thickness confirmed the induction of megacolon in BAC-treated rats. Neuronal counts from BAC and control rats not treated with DMH showed an average denervation of 63%. The number of distal colon carcinomas in BAC+DMH-treated rats was significantly lower than that in DMH-treated rats. These findings appear to contradict the traditional concept of carcinogenesis of the colon. The clinical axiom was reproduced experimentally.

Metoprolol decreases the proportion of rats with abnormal resting ECG in both the acute and the chronic stage of T cruzi infection.

Typical megaileum occurred in young male Wistar rats three months after ileum myenteric plexus denervation. An average of 58.4% denervation of the Auerbach plexus was obtained by serosal application of benzalkonium chloride (0.2% v/v). Denervation was assessed by ganglion cell counts in an 8 nm ring-shaped histological sectfrom the midportion of the treated segment. A morphometric study showed that the increased thickness of the megaileum wall was due to muscle hypertrophy and mucosal hyperplasia. The potential usefulness of this model of megaileum is emphasized.

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A middle-aged woman with long-term uncontrolled arterial hypertension developed a clinical picture of impending myocardial infarction. A normal coronary arteriogram was obtained. However, left heart catheterization showed a marked increase in left ventricular end-diastolic pressure, while left angiocardiography revealed marked left ventricular hypertrophy. She was successfully treated with a beta-blocking and calcium-antagonist agent. The present case shows that an impending myocardial infarction may occur in patients having normal coronary arteriogram but with left ventricular hypertrophy secondary to arterial hypertension.