Parathyroid hormone transport effects and hormonal processing in primary cultured rat proximal tubular cells.

The development of satisfactory cell culture models for the study of parathyroid hormone (PTH)-induced inhibition of Pi transport has proven difficult. Using subcellular fractionation techniques we investigated the response of primary cultures of rat proximal tubular cells to PTH-(1-34). Specific binding of 125I-bPTH-(1-34) occurred at 2 degrees C. After 5 min of rewarming, trypsin-releasable radioactivity decreased from 90 to 50%, indicating internalization of the ligand. Cell disruption, followed by density centrifugation with 17% Percoll either directly after binding at 2 degrees C or post-rewarming for 20 min, showed a shift of 125I label from the plasma membrane (5'-nucleotidase) to lysosomal fractions (beta-D-glucosaminidase), confirming the sequential occurrence of cell surface binding, internalization and transport to lysosomes of 125I-bPTH-(1-34). Reculture at 37 degrees C revealed steady accumulation of trichloroacetic acid-soluble radioactivity in the medium, indicating degradation of 125I-bPTH-(1-34). Phosphate transport in the absence of sodium was minimal. Incubation of the cells with bPTH-(1-34) resulted in up to 50% inhibition of sodium-dependent phosphate transport. Prior phosphate depletion abrogated the response to PTH.

Renal transplantation in patients 65 years old or older.

Between January 1982 and August 1989, cadaveric renal transplantation was performed in 22 patients 65 years old or older. Mean recipient age was 68 years (range 65 to 73 years). There were 17 men and 5 women. Additional risk factors included retransplantation (3 patients), high (greater than 30%) panel reactive antibody (4) and diabetes (1). All patients received cyclosporine as part of the immunosuppressive regimen. The 3-year actuarial patient and allograft survival rates were 89% and 71%, respectively. There were 6 graft losses due to chronic rejection (2 patients), renal vein thrombosis (1), myocardial infarction (1), withdrawal of immunosuppression because of sepsis (1) and primary nonfunction (1). Of the 16 patients with a functioning graft 12 currently have a serum creatinine of less than 2.0 mg./dl. These results suggest that cadaveric renal transplantation is an acceptable form of treatment for patients older than 65 years with end stage renal disease.

Preservation of renal function by percutaneous renal angioplasty in high-risk elderly patients: short-term outcome.

In 17 elderly patients, 19 angioplasties (17 nonostial, 2 ostial) were performed to treat acute decreases in renal function caused by high-grade renal artery stenosis in patients considered to be high-risk surgical candidates. Seventeen angioplasties (percutaneous transluminal renal angioplasty, PTRA) were technically successful and 7 patients showed improved renal function, as reflected by a fall in mean serum creatinine from 566 to 180 mumol/l (6.4 to 2.1 mg/dl). Four others had stabilization of function and 3 out of 4 with acute oliguria improved. Complications included femoral hematoma (4), minor peripheral embolism (3), renal artery thrombosis (1) renal artery dissection (1). One fatal complication was thrombosis of the aortic bifurcation due to catheterization. Four other patients died of cardiovascular causes unrelated to PTRA. Eleven patients experienced stabilization or improvement in renal function, but five out of six PTRA failures required maintenance hemodialysis and died in the hospital. Percutaneous transluminal angioplasty may offer the best change of favorable outcome in selected severely ill elderly patients with uremia, hypertension and renal artery stenosis.

Arteriovenous haemofiltration: a recent advance in the management of renal failure.

Twenty five patients with oliguric renal failure were treated by a combination of continuous arteriovenous haemofiltration and intermittent haemodialysis over 18 months. Haemofiltration was given for a mean of 6.6 days and the mean filtration volume was 6.0 1/day. Fourteen of the 25 patients survived beyond two months after the period of oliguria. Haemofiltration proved to be a simple and effective method of fluid removal; it allowed maintenance of stable fluid balance and permitted optimum nutrition during prolonged oliguria.