The association of depression and all-cause mortality: Explanatory factors and the influence of gender.

BACKGROUND: The association of depression with mortality and the significance of explanatory factors, in particularly gender, have remained an issue of debate. We therefore aimed to estimate the effect of depression on all-cause mortality, to examine potential explanatory factors and to assess effect modification by gender. METHODS: We used Cox regression models to estimate the effect of depression on mortality based on data from the Gutenberg Health Study, which is a prospective cohort study of the adult population in the districts of Mainz and Mainz-Bingen, Germany. Baseline assessment was between 2007 and 2012. Effect modification by gender was measured on both additive and multiplicative scales. RESULTS: Out of 14,653 participants, 7.7% were depressed according to Patient Health Questionnaire 9 (PHQ-9), and 1,059 (7.2%) died during a median follow-up of 10.7 years. Depression elevated the risk of mortality in men and women in age-adjusted models (HR: 1.41, 95%-CI: 1.03-1.92; resp. HR: 1.96, 95%-CI: 1.43-2.69). Adjustment for social status, physical health and lifestyle covariates attenuated the effect and in the fully-adjusted model the hazard ratio was 0.96 (95%-CI: 0.69-1.33) in men and 1.53 (95%-CI: 1.10-2.12) in women. For effect modification by gender, the measure on multiplicative interaction was 0.68 (95%-CI 0.44-1.07) and on additive interaction was RERI=-0.47 (95%-CI -1.24-0.30). LIMITATIONS: The PHQ-9 is a single self-report measure of depression reflecting symptoms of the past two weeks, limiting a more detailed assessment of depression and course of symptoms, which likely affects the association with mortality. CONCLUSIONS: Depression elevates mortality by multifactorial pathways, which should be taken into account in the biopsychosocially informed treatment of depression. Effect modification by gender was not statistically significant.

Cryosurgical monitoring using bioimpedance measurements--a feasibility study for electrical impedance tomography.

The effectiveness of cryosurgery in treating tumors is highly dependent on knowledge of freezing extent, and therefore relies heavily on real-time imaging techniques for monitoring. Electrical impedance tomography (EIT), which utilizes tissue impedance variation to construct an image, is very well suited to cryosurgery since frozen tissue impedance is much higher than that of unfrozen tissue. In this study, we explore cryosurgical monitoring as a previously uninvestigated application for EIT. The feasibility of bio-impedance measurements to detect ice front propagation is demonstrated by freezing planar tissue samples one-dimensionally while measuring impedance along a linear array. The experimental results compare favorably to a simple finite element model designed to provide an electrical field visualization tool.

Composite membrane deformation on the mesoscopic length scale.

The physics of soft materials can be investigated using nuclear spin-lattice relaxation, which depends on the spectral densities of motion in the MHz range. For the first time, NMR relaxation has been used to study influences of the acyl length, polar head groups, a cosurfactant, and cholesterol on the viscoelastic properties of membrane lipids. The results imply the concept of elastic deformation is relevant on lengths approximately equal to the bilayer thickness and less, involving a broad spectrum of collective modes which contribute to the forces between lipid bilayers.

Analysis of cardiolipin molecular species by high-performance liquid chromatography of its derivative 1,3-bisphosphatidyl-2-benzoyl-sn-glycerol dimethyl ester.

Cardiolipin (CL, 1,3-bisphosphatidyl-sn-glycerol) is a four-acyl-chain phospholipid whose molecular species composition cannot be analyzed by standard procedures. Here we report a method to resolve the molecular species of CL by high-performance liquid chromatography of its derivative 1,3-bisphosphatidyl-2-benzoyl-sn-glycerol dimethyl ester. The CL derivative was characterized by 1H nuclear magnetic resonance spectroscopy, ultraviolet (uv) spectroscopy, thin-layer chromatography, and fatty acid analysis. The derivatization procedure did not change the fatty acid profile and provided a virtually complete conversion to the highly apolar, uv-visible product. In HPLC separations, recorded by 228 nm absorbance, a linear correlation was found between the area of individual peaks and their amount of lipid phosphorus. Bovine heart CL was resolved into 11 molecular species of which 6 (together accounting for 97 mol%) could be identified. The molecular species of bovine heart CL feature a linear relationship between their logarithmic retention time and their double bond number.

Stages of the bilayer-micelle transition in the system phosphatidylcholine-C12E8 as studied by deuterium- and phosphorous-NMR, light scattering, and calorimetry.

The perturbation of phospholipid bilayer membranes by a nonionic detergent, octaethyleneglycol mono-n-dodecylether (C12E8), was investigated by 2H- and 31P-NMR, static and dynamic light scattering, and differential scanning calorimetry. Preequilibrated mixtures of the saturated phospholipids 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC), and 1,2-dilauroyl-sn-glycero-3-phosphorylcholine (DLPC) with the detergent were studied over a broad temperature range including the temperature of the main thermotropic phase transition of the pure phospholipids. Above this temperature, at a phospholipid/detergent molar ratio 2:1, the membranes were oriented in the magnetic field. Cooling of the mixtures below the thermotropic phase transition temperatures of the pure phospholipids led to micelle formation. In mixtures of DPPC and DMPC with C12E8, a narrow calorimetric signal at the onset temperature of the solubilization suggested that micelle formation was related to the disorder-order transition in the phospholipid acyl chains. The particle size changed from 150 nm to approximately 7 nm over the temperature range of the bilayer-micelle transition. The spontaneous orientation of the membranes at high temperatures enabled the direct determination of segmental order parameters from the deuterium spectra. The order parameter profiles of the phospholipid acyl chains could be attributed to slow fluctuations of the whole membrane and to detergent-induced local perturbations of the bilayer order. The packing constraints in the mixed bilayers that eventually lead to bilayer solubilization were reflected by the order parameters of the interfacial phospholipid acyl chain segments and of the phospholipid headgroup. These results are interpreted in terms of the changing average shape of the component molecules. Considering the decreasing cross sectional areas in the acyl chain region and the increasing hydration of the detergent headgroups, the bilayer-micelle transition is the result of an imbalance in the chain and headgroup repulsion. A neutral or pivotal plane can be defined on the basis of the temperature dependence of the interfacial quadrupolar splittings.

Ice-Front Propagation Monitoring in Tissue by the use of Visible-Light Spectroscopy.

For demonstrating that visible-light spectroscopy can be used for ice-front detection within freezing tissue, proton magnetic resonance images were correlated to time-evolving transmittance spectra as an ice front progressed across a tissue sample. The experimental apparatus was designed to be compatible with magnetic resonance imaging, to produce one-dimensional freezing, and to allow both reflectance and transillumination emitter-detector configurations about a normally progressing planar ice front in chicken muscle. This demonstration has potentially important medical applications in cryopreservation (freezing of biological materials for preservation) and cryosurgery (destruction of tissue by freezing).

A randomized trial comparing povidone-iodine to a chlorhexidine gluconate-impregnated dressing for prevention of central venous catheter infections in neonates.

UNLABELLED: Neonates who require a central venous catheter (CVC) for prolonged vascular access experience high rates of catheter-related bloodstream infection (CRBSI). PURPOSE: A multicenter randomized clinical trial was undertaken to ascertain the efficacy of a novel chlorhexidine-impregnated dressing (Biopatch Antimicrobial Dressing) on the CVC sites of neonates for the prevention of catheter tip colonization, CRBSI, and bloodstream infection (BSI) without a source. Setting. Six level III neonatal intensive care units. Patients Studied. Neonates admitted to study units who would require a CVC for at least 48 hours. METHODS: Eligible infants were randomized before catheter placement to 1 of the 2 catheter site antisepsis regimens: 1) 10% povidone-iodine (PI) skin scrub, or 2) a 70% alcohol scrub followed by placement of a chlorhexidine-impregnated disk over the catheter insertion site. A transparent polyurethane dressing (Bioclusive Transparent Dressing) was used to cover the insertion site in both study groups. Primary study outcomes evaluated were catheter tip colonization, CRBSI, and BSI without an identified source. RESULTS: Seven hundred five neonates were enrolled in the trial, 335 randomized to receive the chlorhexidine dressing and 370 to skin disinfection with PI (controls). Neonates randomized to the antimicrobial dressing group were less likely to have colonized CVC tips than control neonates (15.0% vs 24.0%, relative risk [RR]: 0.6 95% confidence interval [CI]: 0.5-0.9). Rates of CRBSI (3.8% vs 3.2%, RR: 1.2, CI: 0.5-2.7) and BSI without a source (15.2% vs 14.3%, RR: 1.1, CI: 0.8-1.5) did not differ between the 2 groups. Localized contact dermatitis from the antimicrobial dressing, requiring crossover into the PI treatment group, occurred in 15 (15.3%) of 98 exposed neonates weighing