Temporal profile of serum-induced S-phase entry and retinoblastoma protein phosphorylation in human skin fibroblasts.

Cultured skin fibroblasts from type 1 diabetic patients with nephropathy have a hyperplastic growth phenotype in comparison with diabetics without nephropathy and controls. We studied the G1 phase cyclins in skin fibroblasts from control subjects to define the temporal profile of serum-induced pRB phosphorylation, cyclin D1 protein expression, and cyclin D1/CDK4(6) kinase activity as well as S-phase entry by FACS analysis. Our preliminary studies indicate that cultured skin fibroblasts from type 1 diabetic patients with nephropathy have an enhanced pRB phosphorylation, cyclin D1 protein expression, and cyclin D1/CDK4(6) kinase activity. This finding may become useful to identify patients at risk for the development of nephropathy.

A subdepressor low dose of ramipril lowers urinary protein excretion without increasing plasma potassium.

Angiotensin-converting enzyme (ACE) inhibitors are increasingly administered to patients with chronic renal disease. One issue of concern with the use of ACE inhibitors in patients with impaired renal function is the possible development of hyperkalemia. We reasoned that the impact of ACE inhibitors on plasma potassium could be minimized by administering these agents at very low doses. To examine this issue, we investigated the effect of a low dose of ramipril (1.25 mg orally once daily) and an eight-fold higher dose (10 mg orally once daily) on plasma potassium in 13 patients with proteinuria and mild chronic renal insufficiency. The study was divided into four phases: placebo (4 weeks), low-dose ramipril (8 weeks), high-dose ramipril (8 weeks), and washout phase (4 weeks). With the low dose of ramipril, urinary protein excretion decreased significantly as early as after 1 week of administration (from 4.4 +/- 0.5 to 3.7 +/- 0.4 g/24 h; P < 0.025) and did not decrease any further thereafter even when the dose was increased eight-fold. Mean arterial blood pressure and plasma potassium did not change significantly with the low dose of ramipril, whereas with the higher dose, mean arterial blood pressure decreased significantly (from 107 +/- 2.0 to 100 +/- 2.0 mm Hg, P < 0.005), and plasma potassium increased significantly (from 4.53 to 4.78 mEq/L, P < 0.05). We conclude that a low dose of ramipril can reduce proteinuria to the same extent as an eight-fold higher dose without significantly lowering blood pressure or increasing plasma potassium. This latter feature may be advantageous for the treatment of patients at risk for hyperkalemia who require ACE inhibitors.

Fatal cervical spondyloarthropathy in a hemodialysis patient with systemic deposition of beta2-microglobulin amyloid.

Destructive spondyloarthropathy is a serious complication in patients with end-stage renal disease. We report a case of fatal cervical spondyloarthropathy in a patient on hemodialysis who presented with severe pain in the cervical area. Magnetic resonance imaging (MRI) of the cervical spine showed a soft tissue mass at the cervico-occipital hinge with spinal cord compression and destructive lesions of the cervical vertebrae. The patient became quadriplegic during the MRI procedure and died a few days later. Postmortem examination showed deposition of beta2-microglobulin in the cervico-occipital hinge. A unique feature of this case was the documented presence of systemic beta2-microglobulin amyloid deposits involving the spleen that to our knowledge has not been reported previously. Clinical suspicion and early detection of lesions caused by dialysis-related amyloidosis (DRA) may help to prevent significant morbidity and mortality in long-term dialysis patients.