Effects of acute psychological stress on serum lipid levels, hemoconcentration, and blood viscosity.

BACKGROUND: While there is substantial evidence that psychological stress enhances risk for coronary artery disease, the mechanisms underlying such an influence remain unclear. We examined the effects of short-term psychological stress on serum lipid levels, hemoconcentration, fibrinogen level, and plasma viscosity. METHODS: Forty-four healthy young adults were randomly assigned to perform a distinctly frustrating cognitive task for 20 minutes (stress condition) or to rest quietly for the same period (control condition). RESULTS: Relative to controls, stressed subjects showed significant increases in blood pressure and heart rate; total, low-density, and high-density lipoprotein cholesterol levels; hematocrit; hemoglobin level; and total protein concentration. Stressed subjects also showed significant reductions in plasma volume and increased plasma viscosity and estimated whole-blood viscosity compared with controls. A similar trend in fibrinogen level was not statistically significant. Individual differences in blood pressure and heart rate response to stress correlated highly with changes in total cholesterol levels and hematocrit. CONCLUSIONS: Our investigation provides further evidence that exposure to short-term mental stress elicits hemoconcentration with associated increases in serum lipid concentrations, hemostatic factors, and blood viscosity.

[Therapeutic bilateral renal artery embolization in the nephrotic syndrome]. / Therapeutische bilaterale Nierenarterienembolisation bei nephrotischem Syndrom.

Amyloidosis with renal involvement was diagnosed in a 52-year-old man with Crohn's disease for 15 years. A severe nephrotic syndrome developed (proteinuria 40 g daily) with oedema and arterial hypotension (80/60 mm Hg). As adequate substitution treatment was not possible an attempt at medical renal ablation was made with a combination of captopril (25 mg daily), frusemide (80 mg daily) and indomethacin (200 mg daily). The proteinuria decreased to 18 g daily, but serum creatinine concentration rose to 5.8 mg/dl so that chronic haemodialysis had to be undertaken. Yet the patient's clinical state hardly improved and, because of his poor general condition, bilateral nephrectomy was contraindicated. In consequence bilateral catheter embolization of the renal arteries was performed. The urinary protein loss fell at once to 0.5 g daily. Serum protein rose from 3.1 g/dl under substitution to 5.7 g/dl without. During the following six months, while on chronic haemodialysis, the nephrotic syndrome did not recur. However, cardiac involvement in the amyloidosis was demonstrated so that the prognosis is poor. Permanent bilateral embolization of the renal arteries is a feasible method of managing a treatment-resistant nephrotic syndrome in selected patients.

Adrenergic blockade ameliorates cellular immune responses to mental stress in humans.

This study evaluated the sympathoadrenal modulation of behaviorally evoked immune responses by administration of a nonselective adrenoceptor antagonist (labetalol) to subjects exposed to mental stress. In a 2 x 2 factorial design, subjects were assigned to a labetalol or saline condition and, within each condition, were exposed either to acute laboratory stress or no stress (control). Lymphocyte subsets, natural killer (NK) cell cytotoxicity, and T cell proliferation to phytohemagglutinin and concanavalin A were assessed pre-experimentally, at baseline after infusion and after 18 minutes of mental stress (or rest). By comparison with the other three conditions, the saline-stress group showed a greater peripheral NK cell number and cytotoxicity, lower mitogenic response to phytohemagglutinin and concanavalin A, and diminished ratio of CD4:CD8 cells after the stressor. As predicted, immune responses did not differ among the remaining groups (labetalol-stress, saline-rest, labetalol-rest). Group differences in NK cell cytotoxicity were not significant after controlling for differences in NK cell numbers. These findings demonstrate that the occurrence of certain immunologic responses to acute psychological stress are dependent on concomitant activation of the sympathetic nervous system.

Endovascular creation of an in vivo bifurcation aneurysm model in rabbits.

PURPOSE: To develop a rabbit model of an intracranial bifurcation aneurysm to test new endovascular therapies. MATERIALS AND METHODS: An experimental aneurysm model was created in rabbits by means of endovascular balloon occlusion of the left common carotid artery, which created an aneurysm at the bifurcation formed by the aortic arch and the brachiocephalic trunk. A total of 18 aneurysms were created. In eight rabbits, the aneurysms were incubated with intraluminal elastase to induce degeneration of the elastic laminae. The animals were followed up with angiography for as long as 3 months. The animals were sacrificed at various times, and histologic evaluation of the aneurysm was performed. RESULTS: Ten aneurysms created without elastase infusion were all very small or completely closed at 1-3 months. Six aneurysms created with elastase infusion had long-term patency (two were patent at 1 month and four, at 3 months). The elastase aneurysms had a mean width of 3 mm (range, 2-3.5 mm) and a mean length of 5 mm (range, 3-7 mm). Histologic evaluation revealed destruction of the normal elastin layers, which allowed the artery to become aneurysmal. CONCLUSION: This aneurysm model re-created the hemodynamic forces and size of human cerebral bifurcation aneurysms and maintained the integrity of the endothelium. The creation of the aneurysms was rapid, reliable, and reproducible.