Atrial fibrillation in endurance-trained athletes.

BACKGROUND: Endurance exercise training produces multiple cardiac adaptations including changes in electrophysiological function that may make endurance-trained athletes more vulnerable to atrial fibrillation (AF). This possible association is not recognised by many practising cardiologists and sports physicians. Consequently, we performed a literature review to examine the relationship between atrial fibrillation and endurance exercise training among athletes. PubMed was searched from January 1960 through December 2008 to identify articles examining the relationship between endurance exercise training and AF. RESULTS: Evidence suggests that athletes are at increased risk for development of AF. Possible factors increasing AF in this population include increased parasympathetic tone, reduced sympathetic tone, increased atrial size and increased inflammation. DISCUSSION: Suggested management of AF in athletes should follow similar principles to those used to manage AF in the general population.

Botulinum A exotoxin for rejuvenation of the upper third of the face.

Botulinum A exotoxin, derived from the gram-positive anaerobe Clostridium botulinum, has proven to be safe and effective in the temporary treatment of facial rhytides. In order to obtain reproducible results and avoid complications, it is necessary to understand the relevant physiology and anatomic relationships. Technical considerations including injection technique, dilution, storage, and potential complications will be discussed.

Current perspectives on pacing therapy in cardiomyopathies.

Hypertrophic cardiomyopathy (HCM) is a complex disease that is sometimes difficult to control with medical therapy. Surgical treatment is highly effective but can be associated with significant morbidity and mortality. It has been suggested in uncontrolled studies that patients with obstructive HCM may improve symptomatically when treated with dual-chamber pacing. Several hypotheses have been suggested to explain this phenomenon, but the mechanism still remains unclear. Many recent randomized trials showed much less uniform effects on symptoms than previously reported. These results indicate the need for further comprehensive inquiry into the effects of pacing on HCM before it can be recommended for widespread use. The data on the benefit of pacing therapy in dilated cardiomyopathy are much more recent and limited. Initial optimistic reports have been only partially confirmed.

R-R variability detects increases in vagal modulation with phenylephrine infusion.

High-frequency power, measured from power spectral analysis of R-R variability, reflects vagal modulation of the sinus node. Unexpectedly, a recent study reported a decrease in high-frequency power during the infusion of phenylephrine despite a prolongation of R-R intervals, indicating an increase in vagal activity. To better define the limitations of high-frequency power to quantify vagal modulation, we measured high-frequency power during the infusion of phenylephrine (0.4, 0.8, and 1.2 micrograms.kg-1.min-1) into 10 normal subjects. We found increasing doses of phenylephrine produced progressive increases in systolic blood pressure from 118 +/- 4 to 129 +/- 5 mmHg (P < 0.005), R-R intervals from 881 +/- 44 to 1,274 +/- 69 ms (P < 0.0001), and the logarithm of high-frequency power from 5.83 +/- 0.22 to 7.73 +/- 0.24 ln(ms2) (P < 0.0001). The conclusion was high-frequency power increases with increasing doses of phenylephrine. These data strongly support the ability of high-frequency power to detect an increase in vagal modulation during baroreceptor activation from an increase in systolic blood pressure with the infusion of phenylephrine.

Idiosyncratic pacing with a commercial pacing system analyzer.

An idiosyncratic response of the Medtronic AV Pacing System Analyzers (models 5311 [unipolar] and 5311B [bipolar]) during high output AAI pacing is reported. Using the bipolar analyzer with unipolar cables and a 2734 adaptor, ventricular capture was noted during high output AAI pacing when the ground was displaced from the patient. Using the unipolar analyzer with bipolar cables also resulted in ventricular capture with high output AAI pacing. Implanting physicians should be aware of this phenomenon to avoid false conclusions.

Rapid atraumatic nail plate removal using the cordless cautery unit.

This article describes the use of a handy, battery-powered, thermocautery unit to cut through the nail plate when performing dermatologic surgery involving nail tissue. Thermocauterization of keratin is a simple, atraumatic method of removing portions of the nail plate, so that the underlying soft tissue may be biopsied or treated. The units are inexpensive and safe to operate.

Identification and molecular weight characterization of antigens from Candida albicans that are recognized by human sera.

Antigenic components in the cytoplasmic extract of Candida albicans were examined after fractionation by concanavalin A-Sepharose and DEAE-Sephacel ion-exchange chromatography. Fractions from the DEAE column were tested by fused rocket immunoelectrophoresis for their reactivity with antibodies in the sera of 20 patients with disseminated candidiasis. Three groups of fractions (regions A, B, and C) from the DEAE column were defined by their reactivity with these sera. Immunoblot analysis with 20 human sera identified 18 antigenic components in regions A, B, and C. Region A contained nine antigens, region B contained four antigens, and region C contained five antigens. Region A contained an antigen with an apparent molecular weight of 48,000 that was recognized by 7 of 10 sera from patients with disseminated candidiasis. Immunoprecipitation experiments with labeled proteins from region A and 51 human sera also demonstrated the presence of a major antigen whose apparent molecular weight is 48,000 to 52,000. The 48- to 52-kilodalton protein is an abundant protein in region A and is the most frequently recognized protein by antibodies in the sera of patients with disseminated candidiasis. Patients with disseminated candidiasis had significantly higher levels of antibody (immunoglobulin G) (P less than 0.001) directed against the 48- to 52-kilodalton protein than did patients with noninvasive forms of candidiasis, patients with other fungal infections, or normal, healthy persons.

Concanavalin A causes changes in membrane protein synthesis of human thymocytes.

Human thymocytes maintained in culture for 32-51 h synthesize proteins de novo and incorporate [35S]methionine into specific membrane proteins. Radiolabelling patterns of membranes of thymocytes from different donors are comparable. Concanavalin A activation of human thymocytes in culture does not increase the rate of de novo protein synthesis of membrane proteins but causes specific changes in the pattern of synthesis of membrane proteins with time. After 32 h a radiolabelled band. MW 52 000, is apparent and after 51 h two additional radiolabelled bands MW 35 000 and MW 70 000 are detectable; concomitantly two proteins, MW 80 000 and 100 000 are no longer radiolabelled. These findings reflect changes in gene expression and suggest an acceleration in the normal processing of specific groups of membrane proteins.