Second asymptomatic carotid surgery trial (ACST-2): a randomised comparison of carotid artery stenting versus carotid endarterectomy

Background: Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence. Methods: ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362. Findings: Between Jan 15, 2008, and Dec 31, 2020, 3625 patients in 130 centres were randomly allocated, 1811 to CAS and 1814 to CEA, with good compliance, good medical therapy and a mean 5 years of follow-up. Overall, 1% had disabling stroke or death procedurally (15 allocated to CAS and 18 to CEA) and 2% had non-disabling procedural stroke (48 allocated to CAS and 29 to CEA). Kaplan-Meier estimates of 5-year non-procedural stroke were 2·5% in each group for fatal or disabling stroke, and 5·3% with CAS versus 4·5% with CEA for any stroke (rate ratio [RR] 1·16, 95% CI 0·86–1·57; p=0·33). Combining RRs for any non-procedural stroke in all CAS versus CEA trials, the RR was similar in symptomatic and asymptomatic patients (overall RR 1·11, 95% CI 0·91–1·32; p=0·21). Interpretation: Serious complications are similarly uncommon after competent CAS and CEA, and the long-term effects of these two carotid artery procedures on fatal or disabling stroke are comparable. Funding: UK Medical Research Council and Health Technology Assessment Programme

Environmental pollution changes in membrane lipids, antioxidants and vitality of Scots pine [Pinus sylvestris L.] pollen

Investigations were carried out on pollen grains of Scots pine (Pinus sylvestris L.) collected from trees at 1.5, 3, 4 km and control, 20 km from the Luboń factory producing mineral fertilisers. The percentage of germination of pollen formed close to the pollution source was ca 20% lower compared to the control pollen. Lowered vitality of the pollen was effected in changes of the structure of cytoplasmic membranes. Pollen from the polluted area contained ca 15% less total phospholipids, mainly phosphatidylcholine and phosphatytidylinositol and had a lower content of soluble proteins and less of low molecular antioxidants, such as thiols and ascorbic acid. Composition of total fatty acid in phospholipids fractions showed a significant reduction in the degree of unsaturation of fatty acids. Pollen originating from the polluted area and stored at -30°C showed considerably stronger degradation of cytoplasmic membranes than control

Extended and localized states, polarons, excitons and solitons in irradiated N-methyl derivatives of pyridinium with TCNQ

N-methyl derivatives of pyridinium with TCNQ are 1 : 2 charge transfer salts of tetracyanoquinodimethane. Despite the fact that the TCNQ chains should be a priori quarter filled bands, these systems are insulators with a gap of approximately 0.6 eV. Disordering these systems by irradiation slows down the charge carriers and changes their density. It creates a large variety of new experimental situations where the current carrying, heat carrying and magnetic excitations can be examined and compared. Conductivity and thermopower data concerning 22 nominally pure and irradiated samples of 3 different compounds are presented and discussed together with a preliminary electron spin resonance experiment, and compared to the most current models in the field. In nominally pure samples and at low irradiation doses, a single-electron, extended state semiconducting picture explains surprisingly well the main features of the transport properties. But the success of this phenomenology is only superficial and cannot explain the whole set of results, even when localized states near the band edges are introduced for the purpose of describing the high-disorder limit. The mobilities deduced from the above model are very low (∼ 1 cm2/V . s), even in the non-irradiated samples, and suggest the possible presence of polaronic states. The low disorder to high disorder crossover observed in the transport properties could be viewed as a large polaron to small polaron transition. However, turning on the electron-phonon interaction is, by no means, enough for understanding the insulating character of these compounds. One also needs substantial electron-electron interactions. N-methyl derivatives of pyridinium with TCNQ are either Mott insulators, or spinless fermion half-filled band Peierls insulators. The main current carrying excitations are excitons in the former case and soliton-antisoliton pairs in the latter. Both excitations exhibit the electron-hole symmetry suggested by the experimental results. Possibly pure and irradiated N-methyl derivatives of pyridinium with TCNQ provide an experimental indication of the presence of solitons with charge ± e/2 predicted by Hubbard and Rice.Les molécules dérivées du pyridinium par addition de groupements méthyl forment avec les molécules de TCNQ (tétracyanoquinodiméthane) des sels à transfert de charge de stoechiométrie 1 : 2. L'empilement des molécules de TCNQ en chaînes devrait conduire à la formation de bandes au quart pleines. Malgré cela, de tels systèmes sont des isolants avec un gap proche de 0,6 eV. En désordonnant ces composés, l'irradiation ralentit les porteurs de charge et en modifie le nombre. Elle crée donc une large variété de situations nouvelles permettant de tester la nature des excitations magnétiques et de celles qui transportent du courant ou de l'énergie. Nous avons pour cela mesuré la conductivité électrique et le pouvoir thermoélectrique de 22 échantillons « purs » et irradiés de 3 différents dérivés de la pyridine (avec TCNQ). Nous présentons aussi une expérience préliminaire de résonance paramagnétique électronique et discutons l'ensemble de ces résultats à la lumière des modèles les plus courants. Dans les échantillons nominalement purs ainsi que ceux faiblement désordonnés, un modèle d'électrons indépendants occupant des états étendus (semi-conducteur de bande) rend compte de façon surprenante des traits essentiels du transport. Mais le succès de ces explications phénoménologiques n'est que superficiel et ne peut rendre compte de l'ensemble des propriétés même quand des états localisés sont introduits au bord des bandes pour mieux décrire les comportements électroniques dans les échantillons les plus désordonnés. Les mobilités déduites d'un modèle à un électron sont faibles ( ∼ 1 cm2/V.s) même dans les échantillons dits purs. Elles suggèrent donc la présence très probable d'états polaroniques. La transition entre le comportement à faibles désordres et le comportement à forts désordres peut être considérée comme une transition entre grands et petits polarons. De toutes les façons, l'introduction de l'interaction électron-phonon ne suffit pas à expliquer le caractère isolant de ces composés. Il faut encore introduire de fortes interactions électroniques qui font des dérivés de la pyridine associés à TCNQ soit des isolants de Mott, soit des isolants de Peierls formés à partir d'une bande à demi-pleine de fermions sans spin. Dans le premier cas, c'est l'exciton qui est l'excitation susceptible de créer des porteurs de charge alors que dans le second cas c'est la paire soliton-antisoliton. Toutes deux présentent la symétrie électrontrou que suggère l'expérience. Il est bien possible qu'il s'agisse ici d'une mise en évidence des solitons de charge ± 1/2 prédits par Hubbard et Rice

Characterization of cryoprotective activity of thermal hysteresis protein in evergreen plants

Thermal hysteresis proteins (THPs) inhibit the growth of ice by binding to the surface of ice crystals, preventing the addition of water molecules to cause a local depression of the freezing point. Recent findings demonstrate that apoplastic THPs from Norway spruce show a cryoprotective and also anti-ice nucleation activity (Jarz¹bek et al. 2008). Here, we have focused on the most active THPs from five frost-hardy conifers of North American and Eurasian boreal forest: Abies grandis (Douglas ex D.Don)Lindl., Picea pungens Engelm., Pinus nigra J.F.Arnold, Pinus sylvestris (L.), and Tsuga canadensis (L.) Carriere, and additionally from one alpine (2100 m a.s.l.) evergreen shrub Loiseleuria procumbens (L.). The objective of this study was to determine whether these thermal hysteresis proteins of frost-hardy plants (THPs) influence survival at subzero temperatures by modifying the freezing process and/or by acting as cryoprotectants. Apoplastic extracts were obtained by vacuum infiltration of leaves with 5 mM ascorbic acid, and the extracts were concentrated by using a 10 kDa cutoff Ultrafree centrifugal filter device (Millipore). Proteins were separated by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) (Leammli 1970). Cryoprotective activity of apoplastic proteins was determined with the use of the freeze/thaw inactivation, by four cycles in liquid nitrogen (-196oC) and room temperature while the assay of lactate dehydrogenase (LDH) was performed as described by Wisniewski et al. (1999). Antifreeze activity was determined by using the droplet freezing assay (Vali 1971).vokMyynti MTT, Tietopalvelut 31600 Jokioine