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Blends of two elastomeric ethylene–octene copolymers with similar octene contents having a random (ORC) and a blocky architecture (OBC) are prepared by melt mixing. The thermal and mechanical properties of ORC, OBC and their blends are investigated by DSC, dynamic mechanical analysis and tensile tests. The morphology of the semi-crystalline samples is studied by AFM and WAXS. Two types of crystals have been observed: (i) Orthorhombic crystals forming lamellae with an estimated thickness of about 13 nm composed mainly of long polyethylene-like sequences of OBC that melt a temperature of about 120 °C and (ii) fringed micellar crystals with a thickness of 2–4 nm formed basically by short polyethylene-like sequences of ORC that have melting temperatures between 30 and 80 °C. The amorphous phase contains a relatively homogeneous mixture of segments of both components indicated by the relatively uniform shape of the loss modulus peaks from dymamic-mechanical measurements for all investigated copolymers and blends. ORC crystallization is hindered in blends as indicated by lower melting enthalpies. This might be related to the high octene content of the amorphous phase at the relevant crystallization temperature as well as geometrical constraints since ORC crystallization occurs in an already semi-crystalline polymer. The results of tensile tests show that the mechanical behavior can be tailored via blend composition and morphology of the semi-crystalline material. The findings clearly indicate that blending is a powerful strategy to optimize the properties of polyolefin-based copolymers. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the study was to investigate whether provoked changes of cerebral perfusion pressure and arterial carbon dioxide tension are able to influence the cerebral metabolism of endothelin-1 (ET-1) in a porcine model. Brain tissue oxygen tension, regional cerebral blood flow and mean arterial blood pressure were monitored in 10 healthy pigs during induced hyperventilation (HV), hypertension (HrT) and hypotension (HoT). ET-1 was determined in the arterial and cerebrovenous blood. Microdialysis samples (lactate, glucose and pyruvate) were taken from brain and subcutaneous tissue. A significant decrease (p <0.05) of the arterial ET-1 (1.46±0.33fmol/mL) compared to the baseline (2.18±0.36fmol/mL) was observed after the HoT-period. We detected a positive correlation between cerebrovenous ET-1 and extracellular cerebral glucose (0.68; p <0.05) after the baseline as well as a negative correlation of −0.81 (p <0.005) between the cerebrovenous ET-1 level and the extracellular cerebral lactate after the HoT-period. These data imply that with increasingly pathological changes of the cerebral metabolism endothelin becomes progressively more important in the regulation of cerebral vascular tone. [Copyright &y& Elsevier]

Resveratrol produced by several plants, berries and fruits, including grapes, is one of the best known natural food microcomponents with potent chemopreventive properties towards the most severe contemporary human diseases: cardiovascular sickness, cancer and neurodegenerative pathologies. Demonstration of its mechanism of action also implies the elucidation of the steps of bioavailability and bioabsorption in cells and tissues. In order to estimate the relationships between the amounts of resveratrol taken up by food or drink intake, and the several possible benefits illustrated from in vitro/in vivo experiments and from epidemiological studies, it is essential to demonstrate step by step the route of resveratrol from plasma to the cell active site. In plasma, resveratrol was shown to interact with lipoproteins. This commentary also contains previously unpublished results about interactions between resveratrol and albumin and the enhancement of this binding in presence of fatty acids. We have previously described that resveratrol uptake by hepatic cells involves two processes – a passive one and a carrier-mediated one. Thanks to this last process, resveratrol, while tightly bound to blood proteins, could be largely delivered to body tissues. The intracellular proteic targets of resveratrol remain to be identified. [Copyright &y& Elsevier]

Objective: The aim of the present study was to examine the impact of moderate and profound hyperventilation on regional cerebral blood flow (rCBF), oxygenation and metabolism. Materials and methods: Twelve anesthetized pigs were subjected to moderate (mHV) and profound (pHV) hyperventilation (target arterial pO2: 30 and 20 mmHg, respectively) for 30 min each, after baseline normoventilation (BL) for 1 h. Local cerebral extracellular fluid (ECF) concentrations of glucose, lactate, pyruvate and glutamate as well as brain tissue oxygenation (ptiO2) were monitored using microdialysis and a Licox oxygen sensor, respectively. In nine pigs, regional cerebral blood flow (rCBF) was also continuously measured via a thermal diffusion system. Results: Both moderate and profound hyperventilation resulted in a significant decrease in rCBF (BL: 37.9±4.3 ml/100 g/min; mHV: 29.4±3.6 ml/100 g/min; pHV: 23.6±4.7 ml/100 g/min; p<0.05) and ptiO2 (BL: 22.7±4.1 mmHg; mHV: 18.9±4.9 mmHg; pHV: 13.0±2.2 mmHg; p<0.05). A ptiO2 decrease below the critical threshold of 10 mmHg was induced in three animals by moderate hyperventilation and in five animals by profound hyperventilation. Furthermore, significant increases in lactate (BL: 1.06±0.18 mmol/l; mHV: 1.36±0.20 mmol/l; pHV: 1.67±0.17 mmol/l; p<0.005), pyruvate (BL: 46.4±7.8 μmol/l; mHV: 58.0±10.3 μmol/l; pHV: 66.1±12.7 μmol/l; p<0.05), and lactate/glucose ratio were observed during hyperventilation. (Data are presented as mean±S.E.M.) Conclusions: Both moderate and profound hyperventilation may result in insufficient regional oxygen supply and anaerobic metabolism, even in the uninjured brain. Therefore, the use of hyperventilation cannot be considered as a safe procedure and should either be avoided or used with extreme caution. [Copyright &y& Elsevier]

Neuropathic pain is a major problem in the treatment of cancer pain. We performed a retrospective analysis of 213 cancer patients with neuropathic pain treated by a pain service following the World Health Organization guidelines for relief of cancer pain. Of these, 79% presented with nerve compression pain, 16% with nerve injury pain, and 5% with sympathetically-maintained pain. Whereas nerve compression and nerve injury pain were caused most frequently by cancer growth, sympathetically-maintained pain was caused most frequently by cancer treatment. There were no significant differences in the use of analgesics, the mean pain intensity, or the efficacy of analgesic treatment among the three groups. Nerve injury pain and sympathetically-maintained pain were treated more frequently with adjuvant analgesics, especially antidepressants and anticonvulsants. The variety of different neuropathic pain syndromes should be separated in future studies of the efficacy of different treatment approaches. [Copyright &y& Elsevier]

• The limitations and preparation efforts of different microanalytical methods are discussed. • SEM on wet-etched blend film is sufficient to evaluate the bulk morphology. • ToF-SIMS imaging is a valuable method for the surface analysis of the polymer blend. • PP and HDPE distributions vary between the surface and bulk of HDPE/PP blend film. In this study, the morphology of an immiscible polymer blend system at various regions of interests was analyzed using different microanalytical methods with varying surface sensitivities. As a model immiscible polymer blend, a HDPE/PP (80/20 wt%) polymer film was used. The blend film was subjected to polarized light microscopy (PLM), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and time of flight secondary ion mass spectrometry (ToF-SIMS). The obtained results were compared regarding the sensitivities, informational values and overall applicability of the analytical methods. It was evaluated which methods can be applied for a fast analysis of the morphology (surface and bulk) of the immiscible polymer blend with low preparation efforts, which is especially important for the analysis of new materials, for example materials manufactured via recycling. It was demonstrated that PLM, as well as SEM on wet-etched material, provide sufficient information to evaluate the bulk morphology. Additionally, the presented study shows the advantage of applying ToF-SIMS imaging for the characterization of the surface of immiscible polymer blend. As expected, the domain distribution of HDPE and PP varied between the bulk and the surface of the films. The proposed procedures can be taken as a guideline for other investigations concerning the morphology of heterogeneous polyolefin systems. [ABSTRACT FROM AUTHOR]