SUMMARY In vitamin D deficient rats the influence of diphenylhydantoin (DPH) and phénobarbital (PB) pretreatment on intestinal uptake of 45calcium and on the activity of CaBP was studied. The DPH rats show in contrast to the PB and control rats a significantly reduced intestinal uptake of 45calcium. However, the activity of CaBP was similar in all investigated groups. These results suggest a possibly special effect of DPH on the development of the calcium and bone disorders that have been observed in patients treated with anticonvulsant drugs. RÉSUMÉ On a étudié chez des rats qui manquaient de vitamine D, l'effet d'un pré‐traitement avec de la diphénylhydantoïne (DPH) et du phénobarbital (PB) sur l'absorption intestinale de calcium 45 et sur l'activité du CaPB. Les rats qui avaient du DPH, en opposition aux rats de contrôle et aux rats avec PB, avaient une absorption intestinale de calcium 45 significativement réduite. L'activité du CaPB était cependant semblable chez tous les groupes. Ces résultats suggèrent un effet possible particulier de la DPH sur l'origine des troubles du calcium et du métabolisme des os, qui ont été observés chez des patients en traitement avec des produits anticonvulsivants.

A comparative study of long-term haemodialysis patients investigated the effects of calcium acetate and calcium carbonate on concentrations of serum phosphate, calcium, and parathyroid hormone. It was demonstrated that both substances led to a significant decrease in phosphate and serum parathyroid hormone. Administration of calcium acetate reduced the serum phosphate concentration in 7 weeks from an initial value of 2.08 +/- 0.53 mmol/l to 1.51 +/- 0.39 mmol/l (P less than 0.01). Following a 1-week wash-out period, calcium carbonate reduced the serum phosphate concentration in the same patients from 1.99 +/- 0.62 mmol/l to 1.34 +/- 0.40 mmol/l (P less than 0.01). Of particular significance, however, is the fact that in relation to daily elementary calcium intake, calcium acetate was a considerably more effective binder of intestinal phosphate than calcium carbonate. During administration of calcium acetate only 1.02 g of elementary calcium were required daily in order to reduce the serum phosphate concentration. The same patients, however, required 1.88 g of elementary calcium during calcium carbonate therapy. Complementary studies investigated the influence of an accompanying calcitriol medication. In this instance, too, calcium acetate was shown to be more effective; although the patients developed hypercalcaemia with calcium acetate, this happened more often with calcium carbonate. In summary it can be said that daily calcium loading of the uraemic organism under calcium acetate therapy is reduced by nearly half as compared to calcium carbonate therapy, and that this can be achieved with the same effective decrease of the serum phosphate concentration.

It has recently been reported that patients with acute renal failure requiring hemodialysis have an improved recovery of renal function and a higher survival rate when the dialysis treatments are performed with a biocompatible membrane rather than a bioincompatible membrane. Our data, obtained in 57 patients with acute renal failure, do not support these findings since neither the mortality nor the required number of dialysis sessions could be influenced by using a biocompatible membrane. The survival rate was similar in both groups (64 versus 72%), and renal function was regained in both groups after 6 dialysis sessions. We conclude that when reviewing the literature as well as other factors, the underlying clinical condition or the skill of the physicians is probably more important than the theoretical superiority of biocompatible membranes.

No abstract

Very recently it was reported that the amyloid associated with chronic hemodialysis contains, as a major component, a new form of amyloid fibril protein which is homologous to β₂-microglobulin. As β₂-microglobulin has a molecular weight of 11,600 daltons, investigations were carried out to see whether or not this protein would be handled differently by hemodialysis and hemofiltration, because the latter method especially is capable of eliminating solutes with such a high molecular weight. The results clearly indicate that hemofiltration removes substantial amounts of β₂-microglobulin (about 190 mg per treatment, which represents 80% of daily production). It remains to be clarified whether or not hemofiltration is therefore superior to hemodialysis with regard to amyloid deposit formation.