Depressed expression of calcium receptor in parathyroid gland tissue of patients with hyperparathyroidism.

The factors involved in abnormal parathyroid cell secretory function and growth in patients with primary (I degree) and secondary (II degree) hyperparathyroidism are still incompletely understood. We compared the expression of the calcium-sensing receptor (CaR) at the gene message and the protein level in parathyroid tissue obtained from patients with I degree non-uremic or II degree uremic hyperparathyroidism with that in normal parathyroid tissue, using in situ hybridization and immunohistochemistry techniques. The expression of the CaR mRNA and protein was reduced in most cases of I degree adenoma and II degree hyperplasia, compared with strong expression normal parathyroid tissue. In II degree hyperparathyroidism, expression of both receptor mRNA message and protein was often particularly depressed in nodular areas, compared with adjacent non-nodular hyperplasia. Decreased Ca-R expression in adenomatous and hyperplastic parathyroid glands would be compatible with a less efficient control of PTH synthesis and secretion by plasma calcium than in normal parathyroid tissue.

Evaluation of plasma sodium concentration during hemodialysis by computerization of dialysate conductivity.

Kinetics modeling based on sodium mass balance and changes in conductivity at the dialysate outlet compared to that at the dialysate inlet, led to predicting the plasma water conductivity of the blood inlet. Conductivity transducers, with temperature compensation, located at the dialysate inlet and outlet ports of the dialyzer and connected to a conductimeter, were interfaced with a portable computer for data acquisition. In 38 dialysis sessions, a close relationship was found between estimated plasma water conductivity (CdBi) and measured plasma sodium concentration [Na]Bi, according to the formula: CdBi = 0.101[Na]Bi + 0.37 (n = 38; r = 0.922). The study shows that plasma sodium concentration at the dialyzer inlet could be evaluated, with a standard error of +/- 1.5 mEq/L, by continuous measurement of conductivity gradient between dialysate inlet and outlet.

Determination of cerebrospinal fluid production rate using a push-pull perfusion procedure in the conscious rat.

The inulin dilution technique was used to determine the cerebrospinal fluid (CSF) production rate by means of a push-pull cannula implanted into a lateral ventricle. Artificial CSF containing trace amount of 3H-inulin was perfused for 2 h in conscious rats. 3H-inulin in the effluent reached a plateau level depending on the CSF production rate. The control lateroventricular CSF production was 0.98 microliters/min. Production was reduced to 0.34 microliters/min during a perfusion with acetazolamide (1 mM), a carbonic anhydrase inhibitor.

Utilization of erythropoietin in the treatment of the anemia due to chronic renal failure.

Administration of recombinant erythropoietin constitutes a revolution in treatment of the anemia of chronic dialysis patients. Such treatment has been anxiously awaited. Its realization has been possible thanks to the spectacular progress allowed by the newly developed techniques of recombinant genetics. Correction of this type of anemia can be obtained rapidly and permanently if treatment is continued without interruption. It is followed by a remarkable transformation of the patient's physical and psychic status. The occurrence of certain side effects (e.g., elevation of blood pressure and an increased tendency toward vascular thrombosis), however, requires increased awareness in the follow-up of patients at risk and adaptation of erythropoietin administration to individual needs.