Acute toxic effects of sustained-release verapamil in chronic renal failure.

Four hypertensive patients with chronic renal insufficiency or end-stage renal disease who were treated with sustained-release verapamil hydrochloride subsequently developed acute toxic effects. All four patients developed varying degrees of atrioventricular heart block, hypotension, hyperkalemia, metabolic acidosis, and hepatic dysfunction. Supportive treatment consisted of intravenous catecholamines, sodium polystyrene sulfonate, and dialysis, and all patients recovered completely without any residual hepatic or cardiac disease. Patients with renal impairment who are treated with sustained-release verapamil may accumulate verapamil or its metabolites and develop toxic side effects. We conclude that sustained-release verapamil should be used with caution in this patient population and that patients should be closely monitored for adverse cardiovascular, metabolic, and hepatic side effects.

Clopidogrel-associated thrombotic thrombocytopenic purpura/hemolytic uremic syndrome in a kidney/pancreas transplant recipient.

BACKGROUND: We present a case report of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) developing in a kidney/pancreas transplant recipient after the initiation of treatment with clopidogrel for symptomatic coronary artery disease. METHODS: A 35-year-old male kidney/pancreas recipient developed unstable angina 5 years after transplantation. The patient was treated with clopidogrel as adjunct therapy. A TTP/HUS condition developed, was diagnosed early, and successfully reversed with the implementation of plasmapheresis and cessation of clopidogrel and cyclosporine A. RESULTS: The patient continues taking cyclosporine A with good renal function 6 months after the incident, and successfully underwent coronary artery by-pass grafting 3 months after the event. DISCUSSION: This case demonstrates that early identification and treatment can reverse the TTP/HUS process associated with thienopyridine-derived agents. We strongly recommend that drugs of the thienopyridine class be used cautiously in transplant recipients, especially those taking calcineurin-inhibitors.

Cytology of peritoneal fluid from patients on continuous ambulatory peritoneal dialysis.

Peritoneal fluids from 41 patients on continuous ambulatory peritoneal dialysis (CAPD) were examined. The patients were divided into a short-term group (18 patients with CAPD up to one year) and a long-term group (23 patients with CAPD for one to seven years). Peritoneal fluids from a control group, consisting of ten nondialysis patients with ascites, were also examined. The cellular background of the peritoneal fluids and, in particular, the morphology of the mesothelial cells were studied. The following were found to be significantly increased in the CAPD groups: background lymphocytes, mesothelial exfoliation in three-dimensional clusters, mesothelial nuclear size and the number of mesothelial nucleoli. All of these features increased slightly with an increased duration of the dialysis. These findings emphasize that peritoneal dialysis of any duration can induce significantly atypical changes in mesothelial cells.

Transverse myelitis and optic neuritis in systemic lupus erythematosus: a case report with magnetic resonance imaging findings.

We describe a patient with systemic lupus erythematosus who developed transverse myelitis and optic neuritis. Magnetic resonance imaging showed the presence of an abnormal signal in a normal-sized spinal cord which corresponded to the patient's neurologic deficit. No abnormality was recognized in either optic nerve. Magnetic resonance may prove to be a useful imaging modality for the diagnosis of a transverse myelopathy in systemic lupus erythematosus.

Experimental study of chronic ambulatory peritoneal dialysis. I. Inhibition of protein and amino acid losses by single amino acids.

A successful dog model of the continuous ambulatory peritoneal dialysis patient was developed. These preparations were employed in initial studies of the effects of single amino acid-containing dialysis solutions on the losses of protein and amino acids into the dialysate. A decrease of about 40% in the loss of total amino acids into the dialysate was observed when DL-serine-containing dialysis solutions were employed. The addition of DL-serine, L-lysine, or DL-alanine to the dialysis solutions diminished protein loss into the dialysate by 27-55%. DL-Glutamic acid and DL-aspartic acid were ineffective in this regard.

Collecting duct hydrogen ion secretion in the rabbit: role of potassium.

The purpose of this study was to investigate distal nephron hydrogen ion secretion in the intact animal. The rabbit was chosen as the experimental model because it produces acid urine containing little ammonium. Upon replacement of the usual rabbit diet with milk, plus administration of an acid load (10 mEq/kg), the urine pH fell consistently from very alkaline values (PH greater than 7.4) to 4.8 +/- 0.2. Despite the ability to achieve high urine-to-blood hydrogen ion concentration gradients, the U-B PCO2, an index of collecting duct hydrogen ion secretion, was virtually zero. In these studies, the urine bicarbonate and buffer concentration were comparable to those observed in dog, rat, and man in which a high U-B PCO2 gradient was achieved. The rabbits studied had low plasma potassium concentrations (less than 3 mEq/L). Since potassium deficiency has been implicated in impaired urine acidification, potassium was administered, and it resulted in an increase in collecting duct hydrogen ion secretion as evidenced by a further fall in minimum urine pH during acidemia and a prompt rise in the U-B PCO2 during alkali administration. In summary, rabbits had a very low but not absent rate of collecting duct hydrogen ion secretion. Potassium administration increased the rate of hydrogen ion secretion in a segment of the collecting duct in which hydrogen ion secretion is reflected by an increase U-B PCO2.