Urolithiasis in HIV-positive patients treated with atazanavir.

Among protease inhibitors, atazanavir has not been associated with urolithiasis in clinical studies. We describe 11 cases of atazanavir-associated urolithiasis in patients with human immunodeficiency virus (HIV) infection. Patients with low water intake, high urinary pH, and a prior history of urinary stones may have a higher risk of atazanavir-associated urine crystallization.     

Liver phospholipidosis induced by parenteral nutrition: histologic, histochemical, and ultrastructural investigations

Histochemical and electron microscopic examinations of the liver were performed in 5 adults receiving parenteral nutrition for greater than 18 mo and in 4 adults receiving parenteral nutrition for less than 5 mo. Phospholipidosis, reflected by the presence of cytoplasmic phospholipid deposits at histochemical examination and the presence of multilamellar lysosomes at electron microscopy, was marked and present in hepatocytes, Kupffer cells, and portal macrophages in all 5 patients receiving parenteral nutrition for greater than 18 mo. Mild phospholipidosis, affecting only hepatocytes, was demonstrated in 3 of the 4 patients receiving parenteral nutrition for less than 5 mo. These findings indicate that liver phospholipidosis is relatively common in patients receiving parenteral nutrition and that the degree of liver phospholipidosis depends on the duration of parenteral nutrition. Liver phospholipidosis might be due to intrahepatic accumulation of intravenous phospholipids provided by fat-emulsion sources.     

Role of beta-adrenoreceptor antagonism in the prevention of reperfusion ventricular arrhythmias: effects of acebutolol, atenolol, and d-propranolol on isolated working rat hearts subject to myocardial ischemia and reperfusion

The role of catecholamines in the genesis of ventricular arrhythmias during the reperfusion period following coronary occlusion remains incompletely understood. An isolated rat heart preparation, free from the influence of autonomic innervation or of circulating catecholamines, was used to assess the effects of beta-adrenoceptor blockade. The hearts were prelabeled with tritiated norepinephrine ( NE3H ), and the total radioactivity and that in NE3H were measured in the effluent coronary flow. The left main coronary artery was ligated for 10 minutes after which reperfusion followed. The liberation of NE3H and the development of ventricular tachycardia and fibrillation were monitored throughout. The cardioselective beta-antagonist agent, acebutolol, in a high concentration (1.1 X 10(-4)M), had good beta-antagonist effect in response to the added isoproterenol (10(-6)M); this concentration of acebutolol also suppressed sustained reperfusion ventricular arrhythmias but unexpectedly increased the release of NE3H . Atenolol, another cardioselective agent, did not prevent reperfusion ventricular arrhythmias even in a high concentration of 40 mg/L (1.5 X 10(-4)M). The d-isomer of propranolol, with poorer beta-antagonist properties than the l-isomer, prevented such ventricular arrhythmias in a concentration of 1.3 X 10(-5)M, which was low when compared to that of atenolol. It is proposed that the beta-antagonist activity of the compounds tested could not explain the inhibition of reperfusion ventricular arrhythmias and that another quality such as membrane-stabilizing activity may be involved.     

Imaging microdomain Ca2+ in muscle cells

Ca2+ ions passing through a single or a cluster of Ca2+-permeable channels create microscopic, short-lived Ca2+ gradients that constitute the building blocks of cellular Ca2+ signaling. Over the last decade, imaging microdomain Ca2+ in muscle cells has unveiled the exquisite spatial and temporal architecture of intracellular Ca2+ dynamics and has reshaped our understanding of Ca2+ signaling mechanisms. Major advances include the visualization of "Ca2+ sparks" as the elementary events of Ca2+ release from the sarcoplasmic reticulum (SR), "Ca2+ sparklets" produced by openings of single Ca2+-permeable channels, miniature Ca2+ transients in single mitochondria ("marks"), and SR luminal Ca2+ depletion transients ("scraps"). As a model system, a cardiac myocyte contains a 3-dimensional grid of 104 spark ignition sites, stochastic activation of which summates into global Ca2+ transients. Tracking intermolecular coupling between single L-type Ca2+ channels and Ca2+ sparks has provided direct evidence validating the local control theory of Ca2+-induced Ca2+ release in the heart. In vascular smooth muscle myocytes, Ca2+ can paradoxically signal both vessel constriction (by global Ca2+ transients) and relaxation (by subsurface Ca2+ sparks). These findings shed new light on the origin of Ca2+ signaling efficiency, specificity, and versatility. In addition, microdomain Ca2+ imaging offers a novel modality that complements electrophysiological approaches in characterizing Ca2+ channels in intact cells.     

Occipital infarction revealed by quadranopsia following snakebite by Bothrops lanceolatus

We report a case of snakebite in which envenomation was manifested through impairment of the visual field. The patient, a 46-year-old man, was bitten on the right thumb by Bothrops lanceolatus. Treatment with a specific equine antivenom (Bothrofav) was administered one hour after the bite. With the exception of fang marks, the results of a clinical examination, particularly the neurologic component, were normal. The day after the bite, the patient developed an inferior left lateral homonymous quadranopsia with macular epargne. T2 magnetic resonance imaging showed a right occipital infarction. His condition improved clinically and biologically. This observation of snakebite is the first in which envenomation was accompanied exclusively by an impairment of the visual field. Envenomation by B. lanceolatus is distinct in its incidence of significant thrombotic complications at a distance from the site of the bite.     

Early epileptic seizures in ischaemic stroke treated by mechanical thrombectomy: influence of rt-PA

Journal of Neurology - The epileptogenicity of recombinant tissue-plasminogen activator (rt-PA) has been suggested, but seizures were not evaluated in randomised controlled trials. To evaluate...