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BACKGROUND: Left ventricular hypertrophy is a generalized adaptation to increased afterload, but the growth factors mediating this response have not been identified. To explore whether the hypertrophic response was associated with changes in local insulin-like growth factor-I (IGF-I) gene regulation, we examined the induction of the cardiac IGF-I gene in three models of systolic hypertension and resultant hypertrophy. METHODS AND RESULTS: The model systems were suprarenal aortic constriction, uninephrectomized spontaneously hypertensive rats (SHR), and uninephrectomized, deoxycorticosterone-treated, saline-fed rats (DOCA salt). Systolic blood pressure reached hypertensive levels at 3 to 4 weeks in all three systems. A differential increase in ventricular weight to body weight (hypertrophy) occurred at 3 weeks in the SHR and aortic constriction models and at 4 weeks in the DOCA salt model. Ventricular IGF-I mRNA was detected by solution hybridization/RNase protection assay. IGF-I mRNA levels increased in all three systems coincident with the onset of hypertension and the development of ventricular hypertrophy. Maximum induction was 10-fold over control at 5 weeks in the aortic constriction model, 8-fold at 3 weeks in the SHR, and 6-fold at 6 weeks in the DOCA salt model. IGF-I mRNA levels returned to control values by the end of the experimental period despite continued hypertension and hypertrophy in all three systems. In contrast, ventricular c-myc mRNA content increased twofold to threefold at 1 week and returned to control levels by 2 weeks. Ventricular IGF-I receptor mRNA levels were unchanged over the time course studied. The increased ventricular IGF-I mRNA content was reflected in an increased ventricular IGF-I protein content, as determined both by radioimmunoassay and immunofluorescence histochemistry. CONCLUSIONS: We conclude that (1) hypertension induces significant increases in cardiac IGF-I mRNA and protein that occur coordinately with its onset and early in the development of hypertrophy, (2) IGF-I mRNA levels normalize as the hypertrophic response is established, (3) in comparison to IGF-I, both c-myc and IGF-I receptor genes are differentially controlled in experimental hypertension. These findings suggest that IGF-I may participate in initiating ventricular hypertrophy in response to altered loading conditions. The consistency of these findings in models of high-, moderate-, and low-renin hypertension suggests that they occur independently of the systemic renin-angiotensin endocrine axis.

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Depression is frequently seen in patients following myocardial infarction (MI), many of whom are receiving digitalis glycosides, beta-blockers, or other agents that may exert central nervous system (CNS) effects. In a prospective study of the clinical significance of post-MI depression, 335 patients were assessed using a standardized diagnostic interview for depression at 8 to 10 days, and 190 were reinterviewed at 3 to 4 months. Patients prescribed digitalis, beta-blockers, or other cardioactive medications at hospital discharge were identified. Logistic regression analyses were performed to determine the contribution of these agents to depression at 3 to 4 months, controlling for medical and sociodemographic factors as well as for baseline depression. Treatment with digitalis predicted depression at 3 to 4 months (p less than 0.05); no other medications, including beta-blockers, predicted depression (p greater than 0.10). Digitalis may have CNS effects that contribute to depression post-MI and this finding should be considered in the differential diagnosis of depression in cardiac patients.

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In order to assess the effect of acute, reversible myocardial ischemia on the outcome of programmed ventricular stimulation (PVS), ventricular stimulation was performed at rest, during exercise, and during recovery in 10 patients with coronary artery disease. Of these ten patients, four were tested while off antiarrhythmic drugs and six were tested on antiarrhythmic drug therapy. Nine of the ten patients developed acute myocardial ischemia during exercise PVS. However, in only two of these ten patients ventricular arrhythmia could be induced by PVS, one during exercise and one during recovery.

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Two hundred eighty-three patients admitted to cardiac care units for myocardial infarction at two urban teaching hospitals were interviewed 8 to 10 days after infarction and 171 were reinterviewed 3 to 4 months later. Initially, 45% met diagnostic criteria for minor or major depression, including 18% with major depressive syndromes. Depression was not associated with the severity of cardiac illness but was associated with the presence of noncardiac medical illnesses. Three to 4 months after infarction, 33% of patients met criteria for minor or major depression. The large majority of patients who initially met criteria for major but not minor depression showed evidence of depression at 3 months and most patients with major depression had not returned to work by 3 months. Treatment of major depressive syndromes after myocardial infarction may reduce chronicity and disability, while minor depressive syndromes may be similar to normal grief and tend to be self-limited.

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