Disturbances of renal and erythrocyte calcium handling in rats of the Milan hypertensive strain.

Urinary calcium (Ca) excretion and erythrocyte membrane Ca binding and transport were investigated in rats of the Milan hypertensive (MHS) and normotensive strains (MNS). Despite slightly reduced ionized Ca levels in the serum, MHS significantly increased urinary Ca excretion under fasting conditions (P less than 0.01). Urinary Ca was positively related to sodium (Na) excretion in both rat strains; moreover the urinary Ca:Na ratio was significantly enhanced in MHS rats (P less than 0.05). These data suggest that in MHS, Ca reabsorption in the renal tubular cell is reduced independently of disturbances in Na handling. Adenosine triphosphate (ATP)-dependent Ca transport, reflecting the Ca, magnesium (Mg)-ATPase activity (Ca pump), was measured in inside-out vesicles obtained from erythrocyte membranes. This variable was significantly reduced in MHS (P less than 0.01), with no change in the Ca pump affinity constant for Ca. Calcium binding to erythrocyte membranes, measured in the presence of free Ca concentrations comparable with those of the intracellular fluid, was found to be significantly reduced (P less than 0.01) in MHS rats because of the lower number of Ca binding sites. These abnormalities of red blood cell (RBC) Ca handling are in keeping with the increased Ca clearance observed in the kidney. It is not clear whether the disturbances of renal and erythrocyte Ca handling were a genetic primary defect or a secondary change of membrane function.

Altered kinetics of an intravenous calcium load in idiopathic hypercalciuria.

Increased gut calcium absorption or reduced renal tubular calcium reabsorption have been alternatively reported in idiopathic hypercalciuria with kidney calculi. The present study aimed to investigate the handling of an exogenous calcium load in hypercalciuric stone formers to detect possible differences with regard to tissue calcium metabolism in vivo. A constant rate intravenous calcium infusion (0.2 mmol kg bodyweight per two hours) was carried out on six absorptives and six renals, defined according to the reported criteria, as well as on normal controls from clinical staff. Serum ionized calcium concentration were determined at regular intervals during the infusion and in the four hours after the end of calcium load. Over the same period, urinary calcium excretion was evaluated in timed urine collections. Absorptive and renal hypercalciurics had lower serum ionized calcium levels compared with normal controls at all experimental times, a finding that suggests a faster disappearance of calcium from the circulation. The total body calcium clearance calculated from the area under the curve of the serum calcium concentrations was enhanced in hypercalciuric patients (P less than .001). Although renal calcium excretion was higher in hypercalciurics, renal calcium clearance accounted for only a minor fraction of the total body clearance, suggesting that the reduced serum calcium levels found in the hypercalciurics could not be explained by the renal calcium leak. The enhanced total body calcium clearance found in hypercalciuric subjects is therefore due to an increased tissue calcium uptake. This finding provides indirect evidence of altered cell calcium handling in idiopathic hypercalciura with no difference between the so-called absorptives and renals in terms of the pathophysiologic mechanism.

Pefloxacin versus chloramphenicol in the therapy of typhoid fever.

An open, randomized clinical study was carried out to compare the clinical efficacy and safety of pefloxacin with that of chloramphenicol in the treatment of typhoid fever. Sixty hospitalized patients (40 men and 20 women, aged from 17 to 64 years), affected by severe proven typhoid sepsis, were randomly assigned to treatment with pefloxacin at a daily dose of 1,200 mg for 15 days (Group A) or with chloramphenicol at a daily dose of 2 g for 15 days (Group B). The two groups of patients were statistically homogeneous regarding both age and sex and all patients were followed for 30 days after the end of therapy. In Group A all the patients completely recovered from infection and all the isolated strains of Salmonella typhi were eradicated by pefloxacin treatment. In Group B two patients had a relapse, two patients became chronic enteric carriers of S. typhi and only 26 patients recovered from infection with complete eradication of the pathogen. The results indicate that pefloxacin is as active as chloramphenicol in the therapy of typhoid fever and that pefloxacin could be a valid antibacterial agent to be used together with appropriate hygienic measures for an eradication program of typhoid fever in the endemic countries.