Isometric exercise (IME) produces significant hemodynamic changes in the cardiovascular system. We have used IME to study the effect of age on diastolic left ventricular (LV) function in 100 normal volunteers. The E/A ratio (peak velocity of early/atrial filling phases), deceleration time (DT), and isovolumic relaxation time (IVRT) of the transmitral flow were assessed during echocardiography with pulsed-Doppler ultrasound at rest and at peak IME using handgrip. LV mass index (LVMI) and LV ejection fraction (LVEF) were also calculated. Both E/A and IVRT reduced significantly with increasing age. The LVEF decreased (P <.0001), whereas LVMI increased (P <.05) with advancing age. The LVEF was inversely related to LVMI (P <.05). An inverse relationship was noted between E/A and LVMI (P <.01) during IME. The contribution of the atrial contraction to the total diastolic flow increased significantly with advancing age (P <.02) and increased from 0.29 +/- 0.04 at rest to 0.34 +/- 0.08 during IME (P <.0001). It is concluded that with progressing age, the left ventricle becomes stiffer resulting in a reduction in early filling and a compensatory increase in flow due to atrial contraction. A progressive increase in LVMI, which accompanies aging may contribute to stiffening of the left ventricle and deterioration in diastolic function of the left ventricle. This is exaggerated by IME.
Eleven hyperlipidemic patients took an average of 13 g guar in crispbread form over 2- to 8-week periods. Eight weeks' treatment (seven patients) reduced total serum cholesterol by 13% (P less than 0.002) while high-density lipoprotein cholesterol was unchanged. A 13% nonsignificant reduction was also seen in serum triglyceride. Comparison of blood lipid changes over 2-week periods showed guar crispbread to be as effective as guar given in hydrated (eight patients) or semihydrated form (four patients). In addition total serum cholesterol was lowered significantly (11%, P less than 0.05) in five patients where cholestyramine was ineffective. Due to its acceptability, guar crispbread is likely to prove a useful cholesterol-lowering agent.
Guar gum, a storage polysaccharide galactomannan and a form of dietary fiber, was administered to 10 patients with type II a or b hyperlipidemia for 2 weeks. Five grams of gum was given before each of three meals daily, either in a specially prepared soup or mixed with fruit juice or milk. No other deliberate change of diet was made. Three patients had been taking 12 to 16 g/day of cholestyramine for more than 2 years and one had been taking 1000 mg of clofibrate daily. These drugs were continued throughout the trial. Serum cholesterol levels of all 10 patients had been stable for 6 to 18 months before the trial at the start of which the mean level was 345 +/- 15 mg/dl. After 2 weeks of guar gum the mean was 308 +/- 16 mg/dl, a fall of 10.6% (P less than 0.01). Serum triglyceride was not changed significantly. Guar gum, which can be incorporated into foods, merits further study as a potential hypocholesterolemic agent.
Sixteen non-insulin-dependent diabetic patients, mean age 60 years (range 47-69 years) and duration of diabetes 9 years (2-20 years), completed a randomized cross-over study of three 6-week periods separated by 2-week intervals to minimize carry-over effects, in which their usual bread was replaced by either control bread, guar bread (100 g guar/kg wheat flour), or control bread plus a guar granulate. The mean (+/- SEM) intake of guar taken in bread was 7.6 +/- 0.7 g/day (range 3.1-14.3 g/day). The granulate was taken in a dose of 5 g twice daily which provided 8.3 g guar/day. Significant reductions were found in glycosylated haemoglobin after guar bread (11.5 +/- 0.8% to 10.7 +/- 0.8%; p less than 0.02) and after guar granulate (11.2 +/- 0.8% to 10.6 +/- 0.7%; p less than 0.05) compared with control bread. Total cholesterol was also reduced significantly after both guar bread and guar granulate (p less than 0.01, p less than 0.02), the changes being due to LDL-cholesterol. Dietary intakes and body weight did not change. No significant side-effects were reported; 14 subjects found guar bread more palatable than guar granulate but 8 preferred the granulate for its convenience. We conclude that a lower than convential dose of guar can be effective and palatable. The incorporation of guar into food increases its metabolic benefits and palatability.
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