The renin-angiotensin-aldosterone system in mother and fetus at term

Plasma renin activity, renin substrate, angiotensin II, aldosterone and cortisol were measured concurrently and renin concentration calculated in plasma from mothers during labor and delivery, from cord and from newborn infants. The renin-angiotensin-aldosterone system was found strongly stimulated in both mother and fetus. The high values of plasma renin activity in fetus were due exclusively to the high renin concentrations the substrate concentration being normal. In the mother, however, the markedly elevated renin substrate resulted in a doubling of relative values of renin activity compared to renin concentration. Therefore gradients of renin and renin substrate across the placenta are established, but the resulting renin activity is similar on both sides and the levels of generated angiotensin II are also nearly indentical with a good correlation between these last parameters. Aldosterone is as elevated in mother as in fetus whereas cortisol, due to its binding to transcortin, is twice as high in mother as in fetus. No correlation was found between renin activity or concentration of angiotensin II and aldosterone or cortisol indicating that other factors controlling aldosterone are involved.     

Friction and Wear of Self‐Lubricating Polyimides in Vacuum and Air to High Temperatures

In an increasing number of tribosystems, liquid lubrication cannot be applied or its application has to be avoided for environmental reasons. Examples include both plain bearings and linear guides used in space applications and in industrial vacuum production devices, e.g., for flat screens. Demand has also grown to raise the upper working temperatures of tribosystems and vacuum tribometers to around 300°C. For these reasons, a new formulation of polyimide (P84‐HT) for higher temperatures has been developed. Composites (Sintimid) with selected fillers (MoS₂, graphite, polytetrafluoroethylene, carbon fibres) were previously tested as to their general properties (physical, thermal, mechanical, vacuum stability) in temperatures up to 300°C and as regards the ECSS requirements for materials for operation in space (vacuum). The Sintimid compounds were successfully qualified according to these considerations. This paper reports a study of their mechanical properties and friction and wear behaviour. In particular. the influence of environmental parameters ‐ atmosphere and temperature ‐ and load are discussed and compared to other known materials, e.g., Vespel SP3. The tribological results are discussed in terms of the different filler types and their combinations.     

Intercalated carbon nanotubes as a template for the preparation of supported heteroatomic nanoparticles

Chemistry in confined conditions is explored at the level of the interlayer space of multiwall carbon nanotubes. Starting from preliminary intercalated tubes, a ligand exchange reaction has been successfully conducted within the former Van der Waals gap, resulting in a final dispersion of heteroatomic particles, around 2 nm large and nearly homogeneous in size, on the outer surface of the tubes. Intercalated tubular carbon architectures thus prove to be interesting templates for a bottom-up preparation of chemically complex supported nanoparticles, with potential activities for versatile applications.     

Validation of an overall model describing the effect of three environmental factors on the apparent D-value of Bacillus cereus spores

Several factorial models extending the famous Bigelow model to describe the influence of the heating and recovery pH and a_w conditions on bacterial heat resistance have been developed. These models can be associated in an overall multifactorial model describing the influences of heating and recovery conditions on D values. For Bacillus cereus strain ADQP 407 the model parameters characterising the environmental factor influences (pH, Temperature, a_w) were evaluated. Determination of bacterial heat resistance in cream chocolate have been realised to validate these parameter values and to evaluate the level of the influence of food texture or different compounds not taken account of in the model.     

Determination of five tetracyclines and their epimers by LC-MS/MS based on a liquid-liquid extraction with low temperature partitioning

An LC-MS/MS method is presented for screening five tetracyclines and their epimers in a broad range of food products. The scope of matrices includes meat-, fish-, seafood-based products, various dairy ingredients, infant formulae and fats. The method principle is based on a liquid–liquid extraction with aqueous ethylenediaminetetraacetic acid (EDTA) and acetonitrile followed by a freezing step to promote phase separation at low temperature. After defatting with hexane, sample extracts were evaporated and reconstituted before injection onto the LC-MS/MS system. The addition of oxalic acid in the aqueous mobile phase was mandatory to maintain good peak shape and sensitivity over the run. The screening is based upon a double preparation of each sample, one ‘as such’ and a second one with the analytes spiked in the sample, in order to mitigate the risk of false negative response. The method was validated according to the European Community Reference Laboratories Residues Guidelines. A total of 93 samples were included in the validation by two independent laboratories giving both false-negative and false-positive rates at 0% for all compounds. Over the last two years, 2600 samples were analysed routinely and only one chicken sample was found above the regulatory limit.     

Determination of 105 antibiotic,anti-inflammatory,antiparasitic agents and tranquilizers by LC-MS/MS based on an acidic QuEChERS-like extraction

A procedure for screening 105 veterinary drugs in foods by liquid chromatography tandem mass-spectrometry (LC-MS/MS) is presented. Its scope encompasses raw materials of animal origin (milk, meat, fish, egg and fat) but also related processed ingredients and finished products commonly used and manufactured by food business operators. Due to the complexity of the matrices considered and to efficiently deal with losses during extraction and matrix effects during MS source ionisation, each sample was analysed twice, that is ‘unspiked’ and ‘spiked at the screening target concentration’ using a QuEChERS-like extraction. The entire procedure was validated according to the European Community Reference Laboratories Residues Guidelines. False-negative and false-positive rates were below 5% for all veterinary drugs whatever the food matrix. Effectiveness of the procedure was further demonstrated through participation to five proficiency tests and its ruggedness demonstrated in quality control operations by a second laboratory.     

Functional interaction of the gp80 and gp130 IL-6 receptors in human B cell malignancies

This study investigated the psychological impact of HIV infection through assessment of posttraumatic stress disorder in response to HIV infection. Sixty-one HIV-positive homosexual/bisexual men were assessed for posttraumatic stress disorder in response to HIV infection (PTSD-HIV) using a modified PTSD module of the DIS-III-R. Thirty percent met criteria for a syndrome of posttraumatic stress disorder in response to HIV diagnosis (PTSD-HIV). In over one-third of the PTSD cases, the disorder had an onset greater than 6 months after initial HIV infection diagnosis. PTSD-HIV was associated with other psychiatric diagnoses, particularly the development of first episodes of major depression after HIV infection diagnosis. PTSD-HIV was significantly associated with a pre-HIV history of PTSD from other causes, and other pre-HIV psychiatric disorders and neuroticism scores, indicating a similarity with findings in studies of PTSD from other causes. The findings from this preliminary study suggest that a PTSD response to HIV diagnosis has clinical validity and requires further investigation in this population and other medically ill groups. The results support the inclusion of the diagnosis of life-threatening illness as a traumatic incident that may lead to a posttraumatic stress disorder, which is consistent with the DSM-IV criteria.     

Differential expression of adenosine A1 and A2 receptors in preadipocytes and adipocytes

Multiple physiological functions have been described to be affected by adenosine in numerous cell types. A comparative study of the expression of adenosine receptors has been performed in preadipocytes and adipocytes from rat epididymal fat pad. The results show that, in agreement with its well known antilipolytic effect, adenosine induces a negative modulation of adenylate cyclase via the A1 receptor present in adipocytes. By contrast, the A2 receptor subtype, which is positively coupled to adenylate cyclase, is herein demonstrated to be only expressed in adipose precursor cells. This expression allows, in chemically defined medium, the adenosine analogue NECA, by means of its ability to elevate cAMP concentration, to potentiate differentiation. These findings emphasize the role that adenosine might play as a bimodal regulatory extracellular signal in adipose tissue development.     

Western blot analysis of antibody response to pneumococcal protein antigens in a murine model of pneumonia

Adhesion mechanisms mediated by cytokines have been recognized to play a crucial role in ischaemia-reperfusion mechanisms. Although this phenomenon has been well investigated in organ transplantation, little data is available from upper extremity surgery. Profiles of adhesion molecules (CD11/CD18), key cytokines (TNF-alpha and IL-1), CD4+ and CD8+ lymphocytes, and polymorphonuclear neutrophils were investigated following controlled tourniquet ischaemia of the upper extremity for elective hand surgery. Data suggest that relatively short periods of ischaemia activate a mediator cascade and cell-cell interactions that may be associated with adverse pathopyhsiological effects on peripheral tissues after prolonged ischaemia.