Endogenous antioxidant defense induction by melon superoxide dismutase reduces cardiac hypertrophy in spontaneously hypertensive rats.

We assessed the influence of SODB, a melon superoxide dismutase (SOD), on left ventricular (LV) hypertrophy in SHR. SODB (4 or 40U SOD) was given orally for 4 or 28 days to SHR. For each treatment period, LV weight index (LVWI) and cardiomyocytes size were measured. SOD, glutathione peroxidase (GPx) and catalase expressions, and LV production and presence of superoxide anion were determined. Pro-inflammatory markers were also measured. SODB reduced LVWI and cardiomyocytes size after 4 or 28 days. Cardiac SOD and GPx increased by 30-40% with SODB. The presence but not production of superoxide anion was significantly reduced by SODB. No effect of SODB was detected on inflammatory status in any group. The beneficial effect of SODB on cardiac hypertrophy seems to be related to the stimulation of endogenous antioxidant defense, suggesting that SODB may be of interest as a dietary supplementation during conventional antihypertensive therapy.

Dietary sodium restriction prevents kidney damage in high fructose-fed rats.

Sodium depletion has a protective effect on target-organ damage in hypertension independent of blood pressure. Here we tested whether chronic dietary sodium restriction may prevent the development of renal alterations associated with insulin resistance by reducing the inflammatory and oxidant state. Rats were fed normal-salt-60% fructose, low-salt-60% fructose, or control normal-salt diet for 12 weeks. Insulin resistance induced by high-fructose diet was associated with an increase in albuminuria, tubular and glomerular hypertrophy, and inflammation of kidney and adipose tissue. The low-salt diet improved insulin sensitivity and prevented kidney damage. These beneficial effects of sodium depletion were associated with a decrease in renal inflammation (macrophage infiltration, IL-6, TNF-α) and oxidative stress (NADPH oxidase activity), and a prevention of histologic changes in retroperitoneal fat induced by high fructose. Thus, dietary salt depletion has beneficial effects on renal and metabolic alterations associated with a high-fructose diet in rats.

Early detection of isolated left ventricular diastolic dysfunction in high-risk differentiated thyroid carcinoma patients on TSH-suppressive therapy.

OBJECTIVE: L-Thyroxine-suppressive therapy benefits high-risk differentiated thyroid cancer patients by decreasing recurrence rates and cancer-related mortality. However, fully suppressed serum thyroid-stimulating hormone (TSH) implies a state of subclinical hyperthyroidism (SCH) with associated adverse cardiac effects. Because left ventricular (LV) diastolic dysfunction may be the first manifestation of more severe LV failure, and to balance the risks from thyroid cancer recurrence with risks of cardiac failure, the purpose of this study was to analyse new parameters of LV function in asymptomatic patients with exogenous SCH. DESIGN: Case-control study with 24 patients on TSH-suppressive therapy of short duration (≤ 4 years) after thyroid ablative therapy for differentiated thyroid carcinoma and 20 age- and sex-matched subjects. MEASUREMENTS: LV function [LV global strain and strain rate (SR) curves] was assessed by speckle tracking imaging echocardiography in each subject. RESULTS: Patients and controls do not differ in body mass index, systolic blood pressure and heart rate. No significant differences were observed in LV morphology (LV mass and relative wall thickness), cardiac output and parameters of LV systolic function between patients on suppressive therapy and controls. When compared with controls, patients with exogenous SCH had a significantly impaired longitudinal protodiastolic strain, SR and strain diastolic index but preserved radial strain and SR function. CONCLUSIONS: In subjects with SCH at the early phase of TSH-suppressive therapy, evidence of isolated longitudinal LV diastolic dysfunction was observed, despite a normal LV morphology. Further prospective studies to clarify the prognosis of picking-up early diastolic dysfunction in asymptomatic patients are needed before serial measurements could be recommended.