ETHANOL DECREASES BASAL CYTOSOLIC-FREE CALCIUM CONCENTRATION IN CULTURED SKELETAL MUSCLE CELLS

We analysed the effect of ethanol on basal cytosolic-free calciumconcentration ([Ca²⁺]₁) in cultured rat myocytes. Ethanol causeda dose-dependent decrease of the resting [Ca²⁺]₁). Removal ofethanol was followed by a transitory increase of [Ca²⁺]₁ abovethe basal level. In cells chronically exposed to ethanol, [Ca²⁺]₁normalized to the previous level.     

Quantification of the Modifications in the Dominant Frequency of Ventricular Fibrillation under Conditions of Ischemia and Reperfusion: An Experimental Study

The characteristics of ventricular fibrillatory signals vary as a function of the time elapsed from the onset of arrhythmia and the maneuvers used to maintain coronary perfusion. The dominant frequency (FrD) of the power spectrum of ventricular fibrillation (VF) is known to decrease after interrupting coronary perfusion, though the corresponding recovery process upon reestablishing coronary flow has not been quantified to date. With the aim of investigating the recovery of the FrD during reperfusion after a brief ischemic, period, 11 isolated and perfused rabbit heart preparations were used to analyze the signals obtained with three unipolar epicardial electrodes (E1-E3) and a bipolar electrode immersed in the thermostatizfid organ bath (E4), following the electrical induction of VF. Recordings were made under conditions of maintained coronary perfusion (5 min), upon interrupting perfusion (15 mini, and after reperfusion (5 min), FrD was determined using Welch's method. The variations in FrD were quantified during both ischemia and reperfusion, based on an exponential model AFrD = A exp (-t/C). During ischemia ΔFrD is the difference between FrD and the minimum value, while t is the time elapsed from the interruption of coronary perfusion. During reperfusion ΔFrD is the difference between the maximum value and FrD, while t is the time elapsed from the restoration of perfusion, A is one of the constants of the model, and C is the time constant. FrD exhibited respective initial values of 16.20 ± 1.67, 16.03 ± 1.38, and 16.03 ± 1.80 Hz in the epicardial leads, and 15.09 ±1.07 Hz in the bipolar lead within the bath. No significant variations were observed during maintained coronary perfusion. The fit of the FrD variations to the model during ischemia and reperfusion proved significant in nine experiments. The mean time constants C obtained on fitting to the model during ischemia were as follows: El =294.4 ± 75.6, E2 = 225.7 ± 48.5, E3 = 327.4 ± 79.7, and E4 = 298.7 ± 43.9 seconds. The mean values of C obtained during reperfusion, and the significance of the differences with respect to the ischemic period were: El = 57.5 ± 8.4 (P ± 0.01), E2 = 64.5 ± 11.2 (P0.01), E3 = 80.7 ± 13.3 (P < 0.01), and E4 = 74.9 ± 13.6 (P < 0.0001). The time course variations of the FrD of the VF power spectrum fit an exponential model during ischemia and reperfusion. The time constants of the model during reperfusion after a brief ischemic period are significantly shorter than those obtained during ischemia.     

Spanish and African contribution to the genetic pool of the Canary islanders: data from GM and KM haplotypes and RFLPs in the immunoglobulin IGHG loci

Data on the GM and KM haplotypes and RFLPs in the immunoglobulin IGHG loci are reported intending to evaluate the genetic contribution of the different populations (Europeans and Africans) who settled Tenerife Island. The GM and KM allotypic systems reveal an estimated European genetic admixture of 88%. The only possible African contribution is the presence of the GM * 1 , 17 ;..; 5 * haplotype (2.5%), but no other traces of Black African characteristic haplotypes are found. Although new RFLP haplotypes are described, DNA variation is similar to that reported in Caucasoids with a marked absence of restriction fragments characteristic of Black Africans.     

Wide QRS Complex Arrhythmia with Alternating QRS Morphology: What Is the Mechanism?

A 75‐year‐old man was admitted due to an electrical storm with appropriate recurrent implantable cardioverter defibrillator (ICD) discharges. The patient had had an extensive anterolateral myocardial infarction with associated severe left ventricular dysfunction 10 years earlier (left ventricular ejection fraction, 25%), and an ICD was placed 9 years before admission for primary prevention of sudden cardiac death. A first invasive study induced up to five ventricular tachycardias and an extensive endocardial substrate ablation was performed. Despite intravenous β‐blockers, general anesthesia and procainamide infusion, the patient continued to have recurrent episodes of very slow sustained ventricular tachycardia with a right bundle branch block pattern. In a subsequent invasive study, no mid‐diastolic activity was found despite careful mapping during the induced clinical ventricular tachycardia and ablation attempts inside the apical endocardial scar were unsuccessful. A percutaneous epicardial approach with navigation system support (EnSite Precision^TM Cardiac Mapping System v. 2.0, St. Jude Medical, St. Paul, MN, USA) without antiarrhythmic infusion was planned. A wide QRS complex rhythm with alternating QRS morphology was readily induced by epicardial ventricular pacing trains (Fig. 1, top) that elicited both arrhythmia QRS patterns with very long stimulus QRS intervals (Fig. 1, bottom). What is the possible mechanism of this arrhythmia? Do we need further pacing maneuvers during the arrhythmia to localize critical sites at which ablation pulses can predictably be successful?     

CRYOGLOBULINEMIA AND CUTANEOUS LEUKOCYTOCLASTIC VASCULITIS WITH HEPATITIS C VIRUS INFECTION

Background. Mixed cryoglobulinemia (MC) is a systemic disorder, characterized by a typical clinical triad: purpura, weakness, and arthralgias, with visceral complications such as liver and renal involvement. The objective was to study the association between hepatitis C virus (HCV) infection and essential mixed cryoglobulinemia (EMC). Patients and Methods. Markers of HCV infection in 11 patients with cryoglobulinemia were examined and hepatitis C virus (HCV) was detected in eight of them. These patients were included in a clinical and histologic study. Anti-HCV antibodies were determined by a second-generation enzyme-linked immunosorbent assay (ELISA-2) in sera and cryoprecipitates. Studies on HCV-RNA were performed by a two-stage polymerase chain reaction (PCR) in the serum. A control group, consisting of 28 patients with other cutaneous disorders, was studied for HCV infection using ELISA-2 and PCR. Results. All patients had liver dysfunction, arthralgias, and purpura. Three patients had involvement of the peripheral nervous system, two had renal involvement, and one patient had Sjögren's syndrome. Cryocrits ranged from 3% to 20%. Six patients had type III cryoglobulinemia and the remaining two had type II. Markers for hepatitis B virus (HBV) were negative in all serum samples. Anti-HCV antibodies and HCV-RNA were positive in the serum of all the cases with MC. Anti-HCV antibodies were positive in all cases except for one of the cryoprecipitates tested. Four patients received recombinant interferon alfa. In two of them, serum aminotransferases became normal and cryoglobulins disappeared. Conclusions. The results strongly suggest that HCV infection is responsible for the cryoglobulinemia and vasculitis in patients with MC and that treatment with interferon alfa is presently the treatment of choice for such patients.     

PAPULAR-PURPURIC GLOVES-AND-SOCKS SYNDROME

Background and Objective. Papular-purpuric gloves-and-socks syndrome (PPGSS) is a recently described dermatosis in which human parvovirus B19 (HPV B19) has been implicated as etiologic agent; however, it is suspected that PPGSS may be caused by various agents. This study was designed to survey the general characteristics of PPGSS and to determine the role of HPV B19 in its etiology. Methods. We analyzed data from 21 patients and examined serum samples from three new cases for various viruses. Results. The PPGSS displays a striking uniform clinical pattern. Histologic and immunofluorescence findings are nonspecific. Seroconversion of HPV B19 was reported in six cases and confirmed in two of our patients. In only one case was a possible causative role of Coxsackie virus B6 suggested consistently. Conclusions. The PPGSS represents a distinctive dermatosis and a manifestation of HPV B19 infection. Unlike erythema infectiosum, anti-HPV B19 antibodies seem to develop later after onset of the skin eruption and while viremia is still present.