Value of electrocardiographic leads MCL1, MCL6 and other selected leads in the diagnosis of wide QRS complex tachycardia

To compare the modified precordial leads MCL1 and MCL6 with the conventional precordial leads V1 and V6 and assess the diagnostic accuracy of selected leads for continuous bedside electrocardiographic (ECG) monitoring, 121 wide QRS complex tachycardias were recorded from 92 patients during cardiac electrophysiologic study. As ascertained from intracardiac recordings, 86 tachycardias were ventricular and 35 were supraventricular with aberrant conduction. Early or late peaking of the predominant QRS deflection in lead MCL6 or V6 proved valuable in diagnosing wide complex tachycardia. An interval of less than or equal to 50 ms from the onset of the QRS complex to the predominant peak (or nadir) indicated supraventricular tachycardia; an interval of greater than or equal to 70 ms indicated ventricular tachycardia. The QRS complexes in leads MCL1 and MCL6 were comparable to those in leads V1 and V6 during sinus rhythm. Significant discrepancies in QRS configuration occurred between the modified and conventional precordial leads during ventricular tachycardia, especially between leads MCL1 and V1; however. these differences did not affect diagnostic accuracy. A single MCL1, V1, MCL6 or V6 lead was equally valuable in the diagnosis of wide complex tachycardia and far superior to a single lead II. A combination of leads (MCL1 + MCL6), (V1 + V6), (V1 + I + aVF) or (V1 + V6 + I + aVF) was superior to a single lead or the routinely monitored lead V1 + II combination.     

A Review of the Evidence of Harm from Self-Tests

Although HIV self-testing may overcome some barriers to HIV testing, various stakeholders have expressed concerns that HIV self-testing may lead to unintended harm, including psychological, social and medical harm. Recognizing that similar concerns were raised in the past for some other self-tests, we conduct a review of the literature on a set of self-tests that share some characteristics with HIV self-tests to determine whether there is any evidence of harm. We find that although the potential for harm is discussed in the literature on self-tests, there is very little evidence that such harm occurs.     

Asymmetric Dimethylarginine,Race, and Mortality in Hemodialysis Patients

Background and objectives

Levels of asymmetric dimethylarginine, an inhibitor of nitric oxide synthase, are elevated in kidney disease and associated with mortality in white European hemodialysis populations. Nitric oxide production and degradation are partially genetically determined and differ by racial background. No studies have measured asymmetric dimethylarginine in African Americans on dialysis and assessed whether differences exist in its association with mortality by race.

Design, setting, participants, & measurements

Asymmetric dimethylarginine was measured in 259 patients on maintenance hemodialysis assembled from 2004 to 2012 in Boston area outpatient centers. Cox proportional hazards models were used to determine the association between asymmetric dimethylarginine and all-cause mortality, and an interaction with race was tested.

Results

Mean (SD) age was 63 (17) years, 46% were women, and 22% were African American. Mean asymmetric dimethylarginine in non–African Americans was 0.79 µmol/L (0.16) versus 0.70 µmol/L (0.11) in African Americans (P<0.001); 130 patients died over a median follow-up of 2.3 years. African Americans had lower mortality risk than non–African Americans (hazard ratio, 0.27; 95% confidence interval, 0.15 to 0.50) that was robust to adjustment for age, comorbidity, and asymmetric dimethylarginine (hazard ratio, 0.35; 95% confidence interval, 0.17 to 0.69). An interaction was noted between race and asymmetric dimethylarginine (P=0.03), such that asymmetric dimethylarginine was associated with higher mortality in non–African Americans (adjusted hazard ratio, 1.29; 95% confidence interval, 1.06 to 1.57 per 1 SD higher asymmetric dimethylarginine) but not in African Americans (adjusted hazard ratio, 0.57; 95% confidence interval, 0.28 to 1.18). Additional adjustment for fibroblast growth factor 23 partially attenuated the association for non–African Americans (adjusted hazard ratio, 1.22; 95% confidence interval, 0.98 to 1.50).

Conclusions

African Americans have lower asymmetric dimethylarginine levels and lower hazard for mortality compared with non–African Americans. Levels of asymmetric dimethylarginine did not explain lower hazard for mortality in non–African American patients. High asymmetric dimethylarginine was a risk factor for mortality exclusively in non–African Americans. Mechanisms explaining these relationships need to be evaluated.     

Stabilization of two conformers via intra- or inter-molecular hydrogen bonds in a dinuclear vanadium(v) complex with a pendant Schiff base: theoretical insight

A dinuclear vanadium(v) complex, (μ-O)₂[V(O)(L)]₂, [where HL = 2-methoxy-6-((2-(2-hydroxyethylamino)ethylimino)methyl)phenol] has been synthesized and characterized by spectral and elemental analysis. A single crystal X-ray diffraction study confirms it structure. Two different conformations, stabilized via either intra- or inter-dinuclear hydrogen bonding interactions, co-exist in the solid-state structure. The energies of these intra- or inter-dinuclear hydrogen bonding interactions have been estimated by Density functional theory (DFT) calculations. A ‘Non-covalent interaction’ (NCI) plot has also been used to characterize these interactions.

Two different hydrogen bonded conformers coexist in a synthesized dinuclear oxovanadium(v) Schiff base. Density functional theory (DFT) calculations were utilized to calculate the energies involved in two different conformers.