Semisynthetic resorbable materials from hyaluronan esterification

In recent years, research on new, biocompatible, degradable materials has seen the development of a series of modified natural polymers. Among these, a new class of materials consisting of different hyaluronan derivatives promises to be useful in a whole range of clinical applications thanks to their varied biological properties. These new materials are obtained by chemical modification of purified hyaluronan consisting of the partial or total esterification of the carboxyl groups of this natural polymer. This review on the properties of the new materials reports some of their biocompatibility and characterization aspects based on findings from studies conducted on the ethyl and benzyl hyaluronan esters, two representative members of this new class of compounds, and is intended to arouse interest in the potential of other, as yet unexplored derivatives. From the results of a number of investigations, the various derivatives appear to possess different physico-chemical properties, especially as far as the degree of hydration and polymer stability are concerned. In addition, the type of esterification and extent of chemical esterification of hyaluronan considerably affects the biological properties of these materials, offering a range of polymers either favouring or, conversely, inhibiting the adhesion of certain types of cell.     

Preparation for dialysis treatment using the psychologist

For a long time I have asserted that psychologists should be used in different and wider avenues than they are currently, which limit the tasks and potentialities of psychologists. Psychology is a ductile tool, that besides psychotherapy, sociological and statistical analysis can give answers and solutions in several areas. The Community Psychology approach is one of the innovative models available according to which the psychologist is untied from psychotherapeutic concepts.     

The coefficient of intrinsic dependence (feature selection using el CID)

Measuring the strength of dependence between two sets of random variables lies at the heart of many statistical problems, in particular, feature selection for pattern recognition. We believe that there are some basic desirable criteria for a measure of dependence not satisfied by many commonly employed measures, such as the correlation coefficient, Briefly stated, a measure of dependence should: (1) be model-free and invariant under monotone transformations of the marginals; (2) fully differentiate different levels of dependence; (3) be applicable to both continuous and categorical distributions; (4) should not have the dependence of X on Y be necessarily the same as the dependence of Y on X; (5) be readily estimated from data; and (6) be straightforwardly extended to multivariate distributions. The new measure of dependence introduced in this paper, called the coefficient of intrinsic dependence(CID), satisfies these criteria. The main motivating idea is that Y is strongly (weakly, resp.) dependent on X if and only if the conditional distribution of Y given X is significantly (mildly, resp.) different from the marginal distribution of Y. We measure the difference by the normalized integrated square difference distance so that the full range of dependence can be adequately reflected in the interval [0, 1]. The paper treats estimation of the CID, provides simulations and comparisons, and applies the CID to gene prediction and cancer classification based on gene-expression measurements from microarrays.     

Fibrinogen is negatively correlated with aerobic working capacity in football players

Subjective quality of life in a group of chronic schizophrenia outpatients was assessed within 1 1/2 years (n = 50) and 4-6 weeks (n = 47) using the Berliner Lebensqualit?tsprofil (German version of the Lancashire Quality of Life Profile). There had been no systematic therapeutic interventions meanwhile. Stability and constancy for the longer interval was similar to results in the general population. The statistics for the shorter interval justify in particular use of the profile's total score and general well-being for the measurement of change. In contrast to cross-sectional data and the longer observation period, no significant common variation between psychopathological symptoms and subjective quality of life could be found for the shorter period.     

Increased blood viscosity in iron-depleted elite athletes

The vascular effects of angiotensin converting enzyme inhibitors are mediated by the inhibition of the dual action of angiotensin converting enzyme (ACE): production of angiotensin II and degradation of bradykinin. The deleterious effect of converting enzyme inhibitors (CEI) on neonatal renal function have been ascribed to the elevated activity of the renin-angiotensin system. In order to clarify the role of bradykinin in the CEI-induced renal dysfunction of the newborn, the effect of perindoprilat was investigated in anesthetized newborn rabbits with intact or inhibited bradykinin B2 receptors. Inulin and PAH clearances were used as indices of GFR and renal plasma flow, respectively. Perindoprilat (20 microg/kg i.v.) caused marked systemic and renal vasodilation, reflected by a fall in blood pressure and renal vascular resistance. GFR decreased, while urine flow rate did not change. Prior inhibition of the B2 receptors by Hoe 140 (300 microg/kg s.c.) did not prevent any of the hemodynamic changes caused by perindoprilat, indicating that bradykinin accumulation does not contribute to the CEI-induced neonatal renal effects. A control group receiving only Hoe 140 revealed that BK maintains postglomerular vasodilation via B2 receptors in basal conditions. Thus, the absence of functional B2 receptors in the newborn was not responsible for the failure of Hoe 140 to prevent the perindoprilat-induced changes. Species- and/or age-related differences in the kinin-metabolism could explain these results, suggesting that in the newborn rabbit other kininases than ACE are mainly responsible for the degradation of bradykinin.     

Etude du systeme PbTeTl2Te. Mise en evidence des phases derivées de Tl5Te3

Thallium-lead tellurium system has been investigated by thermal analysis an X-Ray diffraction methods. The cross-section PbTe-Tl₂Te seems to be a quasibinary one. An intermediate phase of stoechiometry Tl₄PbTe₃ has been evidenced. This phase, which decomposes peritectically at 594°C, and his stannous homologous, have been studied by comparison with Tl₅Te₃.     

Increase in the vascular residence time of propranolol-loaded nanoparticles coated with heparin

Propranolol-HCI incorporated nanoparticles prepared with a blend of a polyester and a polycationic polymer and coated or not with a low molecular weight heparin by electrostatic interactions were prepared by emulsification followed by solvent evaporation. The mean diameter was 388 and 357 nm for coated and uncoated nanoparticles, respectively, and the entrapment efficiency ranged from 20 to 32%. Coated nanoparticles were negatively-charged, whereas uncoated nanoparticles displayed a positive zeta potential (+30 mV). After intravenous administration to rabbits of propranolol-HCI solution and propranolol-loaded nanoparticles coated or not with heparin, pharmacokinetic data revealed that coated nanoparticles exhibited a prolonged blood residence time. It can be concluded that the hydrophilic layer of heparin at the surface of nanoparticles conferred stealth properties which probably reduce the phagocytosis process and avoid immediate uptake by the mononuclear phagocytic system.