Can P Wave Wavelet Analysis Predict Atrial Fibrillation After Coronary Artery Bypass Grafting?

VASSILIKOS V., et al. : Can P Wave Wavelet Analysis Predict Atrial Fibrillation After Coronary Artery Bypass Grafting? The purpose of this study was the evaluation of Morlet wavelet analysis of the P wave as a means of predicting the development of atrial fibrillation (AF) in patients who undergo coronary artery bypass grafting (CABG). The P wave was analyzed using the Morlet wavelet in 50 patients who underwent successful CABG. Group A consisted of 17 patients, 12 men and 5 women, of mean age   66.9 ± 5.9 years   , who developed AF postoperatively. Group B consisted of 33 patients, 29 men and 4 women, mean age   62.4 ± 7.8 years   , who remained arrhythmia-free. Using custom-designed software, P wave duration and wavelet parameters expressing the mean and maximum energy of the P wave were calculated from 3-channel digital recordings derived from orthogonal ECG leads (X, Y, and Z), and the vector magnitude (VM) was determined in each of 3 frequency bands (200–160 Hz, 150–100 Hz and 90–50 Hz). Univariate logistic-regression analysis identified a history of hypertension, the mean and maximum energies in all frequency bands along the Z axis, the mean and maximum energies (expressed by the VM) in the 200–160 Hz frequency band, and the mean energy in the 150–100 Hz frequency band along the Y axis as predictors for post-CABG AF. Multivariate analysis identified hypertension, ejection fraction, and the maximum energies in the 90–50 Hz frequency band along the Z and composite-vector axes as independent predictors. This multivariate model had a sensitivity of 91% and a specificity of 65%. We conclude that the Morlet wavelet analysis of the P wave is a very sensitive method of identifying patients who are likely to develop AF after CABG. The occurrence of post-CABG AF can be explained by a different activation pattern along the Z axis. (PACE 2003; 26[Pt. II]:305–309)     

A possible role for mono(ADP-ribosyl)transferase in the signalling pathway mediating neutrophil chemotaxis

1 Mono(ADP-ribosyl)transferase activity has been identified on the external surface of human polymorphonuclear neutrophil leucocytes (PMNs). The enzyme is released from the plasma membrane by phosphoinositide-specific phospholipase C, suggesting a glycosylphosphatidylinositol (GPI) linkage of the enzyme to the plasma membrane. Partial sequence of cDNA encoding the enzyme suggests that it is identical to the GPI-linked mono(ADP-ribosyl)transferase identified previously on human skeletal muscle.
2 A panel of inhibitors of mono(ADP-ribosyl)transferase (including vitamins K₁ and K₃, novobiocin and nicotinamide) showed a rank order of inhibitory potency similar to that described for other mono(ADP-ribosyl)transferases. Furthermore, the mono(ADP-ribosyl)ation of agmatine was inhibited also by diethylamino(benzylidineamino)guanidine (DEA-BAG), another substrate of the enzyme related structurally to arginine.
3 There was a close linear correlation between the I C ₅₀ values for inhibition of mono(ADP-ribosyl)ation of agmatine by DEA-BAG or the enzyme inhibitors and their I C ₅₀ values for inhibition of receptor-dependent polymerization of cytoskeletal actin and chemotaxis.
4 These results suggest a role for mono(ADP-ribosyl)transferase in the transduction pathway involved in receptor-dependent re-alignment of the cytoskeleton during neutrophil chemotaxis.     

EFFECTS OF SOFTFNFD AND UNSOFTFNED FABRICS ON INFANT SKIN

Background. The effects of softened and unsoftened fabrics on the skin of infants of 1–12 months of age were evaluated under real life conditions of skin contact with fabrics. Methods. During 4 weeks, 24 infants wore cotton fabrics washed with a granular detergent on one side of their lower back, and on the other side, cotton fabrics washed with the same detergent and softened with a liquid fabric softener. Skin effects were evaluated by visual grading for redness, dryness, and smoothness, by skin stripping and measuring of Chroma C* (squamometry), by measurements of elasticity and bioelastic ratio, and by instrumental measurements of skin parameters (pH, capacitance, transepidermal water loss (TEWL), and erythema by colorimetry). Results. No deleterious effects were observed in any infant. A decrease in squamometry (Chroma C*) and an increase in capacitance were detected in skin exposed to softened fabrics relative to unsoftened ones. Values of pH tended to be higher in the sites treated with softened versus unsoftened fabrics (pH 6.06 and 5.87, respectively, at end of study). All other parameters showed no significant differences in the two treatment groups. Conclusions. Neither softened nor unsoftened fabrics produced any adverse effects on the skin of infants after continuous wearing during 29 days. A slight beneficial effect on the infants' skin was observed with softened relative to unsoftened fabrics. Methods measuring the structure and function of the stratum corneum were more sensitive discriminators of the effects of fabrics on the skin than traditional methods of visual clinical evaluation.     

REGULATION OF VITAMIN D: AN EVOLUTIONARY VIEW

The regulation of vitamin D metabolism by the kidney is now known to be multifactorial. Three regulatory factors are discussed: 1,25(OH)₂D₃ itself; parathyroid hormone, and phospate. The influence of 1,25(OH)₂D₃ probably depends on new protein synthesis, while the mode of action of phosphate is unknown. Parathyroid hormone is not essential for regulation but may have an important biological role. The direction of its effect varies, perhaps due to a complex inter-relation of changes in calcium and phosphorus metabolism and the level of kidney adenyl cyclase activity.     

Preferred QT Correction Formula for the Assessment of Drug‐Induced QT Interval Prolongation

Drug‐Induced QTc Interval Assessment. Introduction: There is debate on the optimal QT correction method to determine the degree of the drug‐induced QT interval prolongation in relation to heart rate (ΔQTc). Methods: Forty‐one patients (71 ± 10 years) without significant heart disease who had baseline normal QT interval with narrow QRS complexes and had been implanted with dual‐chamber pacemakers were subsequently started on antiarrhythmic drug therapy. The QTc formulas of Bazett, Fridericia, Framingham, Hodges, and Nomogram were applied to assess the effect of heart rate (baseline, atrial pacing at 60 beats/min, 80 beats/min, and 100 beats/min) on the derived ΔQTc (QTc before and during antiarrhythmic therapy). Results: Drug treatment reduced the heart rate (P < 0.001) and increased the QT interval (P < 0.001). The heart rate increase shortened the QT interval (P < 0.001) and prolonged the QTc interval (P < 0.001) by the use of all correction formulas before and during antiarrhythmic therapy. All formulas gave at 60 beats/min similar ΔQTc of 43 ± 28 ms. At heart rates slower than 60 beats/min, the Bazett and Framingham methods provided the most underestimated ΔQTc values (14 ± 32 ms and 18 ± 34 ms, respectively). At heart rates faster than 60 beats/min, the Bazett and Fridericia methods yielded the most overestimated ΔQTc values, whereas the other 3 formulas gave similar ΔQTc increases of 32 ± 28 ms. Conclusions: Bazett's formula should be avoided to assess ΔQTc at heart rates distant from 60 beats/min. The Hodges formula followed by the Nomogram method seem most appropriate in assessing ΔQTc. (J Cardiovasc Electrophysiol, Vol. 21, pp. 905‐913, August 2010)