Clinical characteristics of patients with hypertension resistant to antihypertensive drug therapy

Two groups of hypertensive patients: 137 responsive (on one or two drugs) and 162 resistant on antihypertensive treatment in the similar age were compared. Resistant patients (on three or more drugs) characterize by significantly higher body weight and BMI, longer history of hypertension, more frequent hypertension prevalance in family members and lower education. Level of triglycerides in resistant on antihypertensive treatment patients was significantly higher than in responsive patients. Insulin level in blood in 31 patients with essential hypertension was significantly higher than in 36 healthy persons and 20 patients with renovascular hypertension and resistant on antihypertensive therapy. In 14 patients with essential hypertension resistant to treatment insulin level one hour after oral glucose load was significantly (p < 0.01) higher than in 16 patients with essential hypertension responsive to antihypertensive treatment.     

A high shear rate, high pressure microviscometer

The development of a high shear rate, high pressure microviscometer is described. This viscometer was developed specifically to examine a highly loaded, dynamic contact generated in a small volume of fluid. The viscometer was used to examine the fluid film formed by the mechanism of elastohydrodynamic lubrication in the presence of an SAE 50 oil. A complete numerical analysis of the resulting elastohydrodynamic contact was performed.     

The Growth of Thin Lubricating Films of Plant Oils

The extreme conditions of high pressure and shear imposed in a lubricated sliding contact could influence tribochemical reactions that could occur over long sliding distances and time scales, possibly leading to changes in both friction and film thickness. Experiments conducted with 12 plant oils reveal for the first time, that thin lubricating films of some plant oils can grow to thicknesses much greater than what is predicted from either elastohydrodyamic theory or their adsorbed molecular heights. Some films grew as much as 25 times in thickness (unrefined canola oil), while others remained roughly unchanged (flaxseed and olive oil), or grew slightly and then collapsed during the test (safflower oil). The absence of a loss in film thickness and the viscoelastic-like behavior of the film when speeds are reduced to zero, support the view that polymerization could be the main mechanism of film growth. However, the lack of correlation between the degree of unsaturation and the film growth rate suggests that other mechanisms could also be at work.     

Mitochondrial creatine kinase is a prime target of peroxynitrite-induced modification and inactivation

The reaction of peroxynitrite (PN) with sarcomeric mitochondrial creatine kinase (Mib-CK; EC 2.7.3.2) was observed at different stages of complexity (i) with purified Mi-CK, (ii) with enzyme bound on isolated mitoplasts, and (iii) within intact respiring mitochondria. Creatine-stimulated respiration was abolished by PN concentrations likely to be physiological and far before the respiratory chain itself was affected, thus demonstrating that Mi-CK is a prime target for inactivation by PN in intact mitochondria. The inactivation by PN of Mi-CK was reversed by 22% with 2-mercaptoethanol. More remarkable protective effects were noticed with the full set of CK substrates, e.g. 30 and 50% protection with MgATP plus creatine and MgADP plus phosphocreatine, respectively, but not with each substrate alone. These data indicate an involvement of the active-site Cys-278 residue of Mi-CK in this process. Furthermore, changes in endogenous tryptophan fluorescence intensity and spectral changes after reaction of Mi-CK with PN suggest additional modifications of Trp and Tyr residues. PN-inactivated Mi-CK can no longer be efficiently converted into dimers by incubation with reagents inducing a transition state analog complex at the active site. Thus, obviously, upon reaction of octameric Mi-CK with PN, the octamer-dimer equilibrium of Mi-CK is also affected. The consequences for cellular energy homeostasis and calcium handling are discussed.     

Thermal Conductivity of O2- and N2-Doped Solid CH4

Thermal conductivity investigations in phase II of solid methane with oxygen and nitrogen impurities were carried out in the temperature range from 1.4 to 20 K. The concentration of impurity molecules did not exceed 1%. A significant reduction of thermal conductivity of doped crystals as compared to pure methane has been discovered. Analysis shows that the reduction of thermal conductivity is connected with the deformation of the spectrum of methane molecules due to a crystal field of symmetry O_h. The results obtained for different impurities are discussed in connection with the intrinsic properties of the molecules involved.     

Multifunctional Transmembrane Protein Ligands for Cell‐Specific Targeting of Plasma Membrane‐Derived Vesicles

Liposomes and nanoparticles that bind selectively to cell‐surface receptors can target specific populations of cells. However, chemical conjugation of ligands to these particles is difficult to control, frequently limiting ligand uniformity and complexity. In contrast, the surfaces of living cells are decorated with highly uniform populations of sophisticated transmembrane proteins. Toward harnessing cellular capabilities, here it is demonstrated that plasma membrane vesicles (PMVs) derived from donor cells can display engineered transmembrane protein ligands that precisely target cells on the basis of receptor expression. These multifunctional targeting proteins incorporate (i) a protein ligand, (ii) an intrinsically disordered protein spacer to make the ligand sterically accessible, and (iii) a fluorescent protein domain that enables quantification of the ligand density on the PMV surface. PMVs that display targeting proteins with affinity for the epidermal growth factor receptor (EGFR) bind at increasing concentrations to breast cancer cells that express increasing levels of EGFR. Further, as an example of the generality of this approach, PMVs expressing a single‐domain antibody against green fluorescence protein (eGFP) bind to cells expressing eGFP‐tagged receptors with a selectivity of ≈50:1. The results demonstrate the versatility of PMVs as cell targeting systems, suggesting diverse applications from drug delivery to tissue engineering.     

Evaluation of Discretisation and Integration Methods for the Analysis of Hydrodynamic Bearings With and Without Surface Texturing

Surface texturing has been demonstrated to improve tribological performance of hydrodynamic bearings. Because the texturing increases complexity of a surface, numerical methods are required. However, no comparison study has so far been conducted to determine which methods are most accurate with the least number of grid/mesh points. Knowing this would allow for the analysis and optimisation of bearings with complex geometries. In this work, performance of four discretisation methods (finite difference, finite element, finite volume and spectral element (SE)) in approximating the pressure function and three integration methods (Newton–Cotes formulas and Gauss quadrature) in approximating the load capacity, coefficient of friction and film height was evaluated in a systematic manner. Three slider bearing geometries were used: inclined surface without texturing and two parallel surfaces textured with trapezoidal and quadratic dimples. For the evaluation, pressure function, load capacity, coefficient of friction were calculated analytically using the Reynolds equation. Differences between the analytical values and their approximations produced by the numerical methods were calculated versus the number of grid/mesh points. The numbers of points were determined for the differences below 5, 1 and 0.1 %. Results showed that the SE method and the Gauss quadrature were most accurate regardless of the bearing geometry and used up to 28 times fewer points as compared to other methods.