Diffusive and convective transfer of cytokine-inducing bacterial products across hemodialysis membranes.

The widespread use of bicarbonate dialysate, and high-flux and high-efficiency dialyzers have raised concerns regarding the transmembrane passage of bacterial products from the dialysate into the blood compartment. To study the mechanisms as well as magnitude of the transmembrane transfer of bacterial products from the dialysate, we developed a computerized in vitro dialysis model which provides continuous pressure recording from the arterial, venous, dialysate inflow and outflow ports. By virtue of a computer controlled on-line infusion pump, this model permits control of ultrafiltration/backfiltration. Heparinized (10 U/ml) whole blood (150 ml) was circulated through the blood compartment for 120 minutes at 100 ml/min. Bicarbonate dialysate contaminated with Pseudomonas maltophilia filtrate was circulated through the dialysate compartment at 100 ml/min. A two-point pressure of -10 mm of Hg (ultrafiltration) was maintained for the first 60 minutes and -10 mm of Hg (backfiltration) for the next 60 minutes. Whole blood samples (10 ml) were drawn from the blood at 0, 60 and 120 minutes. Peripheral blood mononuclear cells (PBMC) harvested from these samples were incubated for 24 hours in tissue culture medium. In addition, 0.5 ml samples of dialysate were collected at 0, 60 and 120 minutes and incubated with PBMC from the same donor for 24 hours. After 24 hour incubation, total cell-associated IL-1Ra and IL-1 beta were measured by specific radioimmunoassay. Paired experiments were performed with eight high-flux synthetic membranes (polyamide) and eight low-flux cellulose membranes (hemophan). Cytokine production is expressed as pg/2.5 million PBMC.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac sarcoidosis. An unusual form of acute congestive cardiomyopathy.

We report the case of a previously healthy 45-year-old white man in whom sustained ventricular tachycardia and severe myocardial dysfunction were the only signs of cardiac sarcoidosis. Diagnosis was confirmed by endomyocardial biopsy, and the patient responded well to treatment with amiodarone and prednisone.

The development of laser angioplasty.

Recent developments in technology have stimulated interest in the use of catheter-directed laser energy for removal of atherosclerotic plaques. Over the past three years, intensive research efforts by a number of investigators have defined the potential therapeutic benefit of laser angioplasty, as well as its limitations. Unlike balloon angioplasty, the laser has the capacity to remove totally atheromatous plaque or thrombus by photovaporization. Unique properties of the laser allow light energy to be concentrated for plaque removal. Arterial damage adjacent to the plaque is prevented by certain lasers, while others produce thermal injury to the arterial wall. Chemical pretreatment with vital dyes or drugs has been shown to enhance absorption of laser radiation by plaque and may enable selective destruction of the arterial plaque. Fiberoptic catheters have been designed to transmit laser energy to remote intravascular targets; however, precise guidance systems for catheter delivery have not been developed sufficiently for safe intracoronary application. Complete arterial healing by endothelial cell migration has been demonstrated after laser ablation of plaque in animal studies. Among the first four clinical trials of laser angioplasty, relief of atherosclerotic obstruction was successful using argon, neodymium-YAG, and carbon dioxide lasers. Despite the satisfactory initial appearance of laser-treated arteries, the long-term effects and risk of atherogenesis are undetermined. A potential risk of thrombosis has been identified after laser application, especially with the argon and NdYAG lasers. Further basic and clinical research are needed to establish the role of this promising new technology in the treatment of cardiovascular disease.

Neurologic complications of lymphomatoid granulomatosis.

Lymphomatoid granulomatosis is a malignant form of pulmonary angiitis that has characteristics in common with Wegener granulomatosis and lymphoma. Neurologic symptoms occur in up to 30% of the cases and are the presenting complaints in up to 21%. CNS, cranial nerve, and peripheral nerve involvement occur singly or in combination. In the CNS there is a pathologic triad of angiitis, lymphoreticular infiltration, and necrosis. In the involved peripheral nerves there is demyelination and lymphoid cell infiltration. Neurologic involvement tends to indicate a worse prognosis. Treatment has been based on steroids and cytotoxic agents and may improve symptoms but does not seem to alter the disease process.