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

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