The acute biochemical effects of four proprietary calcium preparations.

Changes in serum and urine biochemical indices have been studied in ten normal subjects in the four hours following the ingestion of four proprietary calcium supplements. Each was taken in a dose containing 1 gram of elemental calcium. The four preparations were ranked according to the amount of calcium absorbed in the order Spar-Cal and Calcium Sandoz greater than Os-Cal greater than Ossopan. There were no significant differences between the four preparations in the changes in parathyroid hormone (PTH) and urine hydroxyproline levels. For this reason, the four results from each subject were averaged. Following the calcium load there was a reduction in mean PTH from 0.16 +/- 0.01 to 0.10 +/- 0.02 micrograms/l (p less than 0.001) and a decline in urine hydroxyproline/creatinine ratio from 20 +/- 1 to 17 +/- 1 (p less than 0.02), suggesting that bone resorption responds immediately to dietary calcium intake. There was a rise in urine sodium excretion which correlated with the indices of calcium absorption (r = 0.63, p less than 0.01) but not with the sodium content of the calcium preparations. This effect could be important, particularly in elderly patients on borderline sodium intakes.

Enalapril in patients with chronic heart failure: a placebo-controlled, randomized, double-blind study.

A number of studies have shown short-term hemodynamic and symptomatic improvement in patients with congestive heart failure treated with angiotensin converting-enzyme inhibitors. The long-term efficacy of the oral long-acting converting-enzyme inhibitor enalapril remains to be established in controlled studies. We evaluated this drug in 36 patients with New York Heart Association functional class II to III heart failure who were clinically stable on digoxin and diuretic therapy. After baseline assessment of symptoms, exercise capacity, and results of echocardiographic examination and right heart catheterization, patients were randomly assigned to treatment with 5 mg enalapril twice daily (n = 18) or placebo (n = 18) in a double-blind fashion. The two groups had similar clinical, echocardiographic, and hemodynamic characteristics before treatment. After 3 months of treatment, the enalapril group showed a significant improvement as judged by subjective patient impression, functional class, and exercise duration (9.3 +/- 5.7 vs 17.6 +/- 5.6 min; p less than .001). Diuretic dosage was reduced in six patients and increased in one patient, one patient had died and another had been withdrawn from the study. In the placebo group there was no significant change with respect to patient impression, functional class, or exercise duration; diuretic dosage was increased in seven patients and four patients had died. Echocardiographic left ventricular dimensions were significantly reduced and left ventricular shortening fraction significantly increased in the enalapril group but were unchanged in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Tangier disease with normal serum cholesterol.

Three patients with Tangier Disease (hypoalphalipoproteinaemia) from the same family are described. One shows the classically described lipid abnormalities of the disease, with a low serum cholesterol level, and almost absent high density lipoprotein (HDL). However, two of his siblings, although demonstrable as Tangier homozygotes, have serum cholesterol levels within the normal range. This anomaly has arisen because they are also heterozygous for familial combined hyperlipidaemia. The pattern of inheritance of the two disorders, Tangier Disease and combined hyperlipidaemia, appears to be unrelated.

Immune complex-like activity associated with abnormal serum lipoproteins in systemic erythematosus.

Sera from four patients with systemic lupus erythematosus (SLE) were shown to contain abnormal lipoproteins which behaved as immune complexes (IC). One IC lipoprotein (IC VLDL) had the density in ultracentrifugation of very low density lipoprotein, but a markedly altered electrophoretic mobility. A second IC lipoprotein (IC LDL) had the electrophoretic mobility of very low density lipoprotein but was slightly denser than low density lipoprotein on ultracentrifugation. Both the IC VLDL and IC LDL contained IgG and behaved as IC in the Clq deviation test, platelet aggregation and rheumatoid factor inhibition assays, but not in the conglutinin and Clq binding assays and the Clq solid phase assay. These differences could be due to the low densities of the IC VLDL and IC LDL. The abnormal lipoprotein IC disappeared with clinical remission in two patients and were not present in the sera of other patients with inactive or mild SLE, Type IV hyperlipidaemia, or during prednisone therapy or plasma exchange for other conditions. These IC appeared to be markers of severe and active SLE.

Very low density lipoprotein metabolism in domestic pigs.

Patterns of triacylglycerol (TG) turnover in plasma and liver, and the hepatic secretion of very density lipoprotein triacylglycerol (VLDL TG) into the circulation, have been studied in young Large White female pigs, using i.v. tracer [1,3-14C]- and [2-3H]glycerol. Serial measurements were made of plasma [14C]glycerol and [14C]glucose and of liver TG and plasma VLDL TG specific activities. In other studies VLDL TG obtained from a donor pig was reinjected into recipient animals to measure the early disappearance (dilution) of VLDL TG. Multicompartmental analysis revealed a mean rate of hepatic TG turnover somewhat slower than the rate of VLDL TG turnover, suggesting that almost all of the hepatic TG turnover was due to secretion of VLDL TG, and that the intestine probably contributed an appreciable part of the newly synthesized plasma VLDL TG. The t1/2 of reinjected VLDL TG, whether prepared by the most rapid possible techniques and reinjected immediately or stored for several days, was approximately 10 min. This was much faster than the t1/2 of the falling limb of the plasma VLDL TG curve seen after injection of labelled glycerol (t1/2 approximately 2 H). Thus, in these respects, the pig resembled all other species studied rather than human subjects as described by Farquhar et al.

Intracellular pH of frog sartorius muscle.

A weak base, morpholine, has been labelled with 3H and tested for its suitability as an indicator for intracellular pH, by distribution in the tissue water of frog sartorius muscle in the species Hyla litoria. Its pK'a at 20 degrees C in a solution of the same ionic strength as frog Ringer was found to be 8.45 +/- 0.02, which is in the range of maximal sensitivity. Morpholine equilibrated with the tissue in 17 h; it was shown that it was not bound to intracellular constituents, that it was not metabolised nor toxic in the concentrations used; it was therefore judged suitable as a pH indcator. Intracellular pH was then measured by distribution of morpholine (6.985 +/- 0.08), nicotine (6.915 +/- 0.03) and the weak acid 5,5'-dimethyl-2,4-oxazolidinedione (7.10 +/- 0.05) and the pH-sensitive microelectrodes (5.9, the equilibrium value). It was shown that the four significantly different values could not be reconciled in terms of experimental error, heterogeneity of intracellular pH, liquid junction potential differences, or binding of indicator molecules inside the fibre. They could, however, be reconciled if the fibre water had different structure and solvent properties from the extracellular water and all ions were distributed across the membrane as between two liquid phases containing different solvents. Then the H+ would be in equilibrium, as shown by the microelectrode measurement, but intracellular pH would be indeterminable and probably greater than 6.