g.

inductive reasoning) might also be compromised in non-clinical schizotypy. (C) 2007 Elsevier Ireland Ltd. All rights reserved.”
“Background: A novel self-expanding drug-eluting stent was designed to slowly release everolimus to prevent restenosis following peripheral arterial intervention. The purpose of the first-in-human Superficial Femoral AZD1208 datasheet Artery Treatment with Drug-Eluting Stents (STRIDES) trial was to evaluate the safety and efficacy of this device for the treatment of symptomatic superficial femoral and proximal popliteal arterial occlusive disease.

Methods and Results: One hundred four patients were enrolled at 11 European investigative centers in a prospective, nonrandomized,

single-arm trial. check details The patients had severe symptomatic vascular disease, including a significant proportion of patients with critical limb ischemia (17%), diabetes (39%), and single-vessel outflow (26%). The mean lesion length was 9.0 +/- 4.3 cm. Ninety-nine percent of patients were available for 12-month follow-up, including duplex imaging in 90% and arteriography in 83%. Clinical improvement, defined as a sustained decrease in Rutherford-Becker clinical category, was achieved in 80% of patients. Primary patency (freedom from >= 50% in-stent restenosis) was 94 +/- 2.3% and 68 +/- 4.6% at 6 and 12 months, respectively. Plain radiographic examination of 122 implanted devices at 12 months revealed no evidence for stent fracture.

Conclusions: The everolimus-eluting Entinostat cost self-expanding nitinol stent can be successfully implanted in patients with severe peripheral arterial disease with favorable outcomes and clinical improvements observed in the majority of patients. (J Vase Surg 2011;54:394-401.)”
“Selective heart rate (HR) reduction by I-f-channel inhibition is a recently developed pharmacological

principle in cardiovascular therapy. Among these newly identified HR-lowering drugs, only ivabradine has now become approved for clinical use. I-f-channel inhibition mainly reduces HR, thereby improving myocardial oxygen supply, energy balance, and cardiac function. Ivabradine was well tolerated and revealed a good safety profile in the investigated study populations. The guiding experimental and clinical results of I-f-channel inhibition were compared to those of beta-blockade as a HR reducing principle as well as cornerstone of heart failure standard therapy. Beside its use in therapy of coronary artery disease, I-f-channel inhibition potentially exhibits beneficial effects in systolic and diastolic heart failure as well. Therefore, hemodynamic effects of ivabradine and its limitations in heart failure together with the biological impact of HR reduction will be considered in this context.

These findings suggest that prism adaptation may primarily affect motor-intentional ‘aiming’ bias in poststroke spatial neglect patients. NeuroReport 22:700-705 (C) 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.”
“Ebola virus (EBOV) causes severe hemorrhagic fever, for which

therapeutic options are not available. Preventing the entry of EBOV into host cells is an attractive antiviral strategy, which has been validated for HIV by the FDA approval of the anti-HIV drug enfuvirtide. To LXH254 order identify inhibitors of EBOV entry, the EBOV envelope glycoprotein (EBOV-GP) gene was used to generate pseudotype viruses for screening of chemical libraries. A benzodiazepine derivative (compound 7) was identified from a high-throughput screen (HTS) of small-molecule compound libraries utilizing the pseudotype virus. Compound

7 was validated as an inhibitor of infectious EBOV and Marburg virus (MARV) in cell-based assays, with 50% inhibitory concentrations (IC(50)s) of 10 mu M and 12 mu M, respectively. Time-of-addition and binding studies suggested that compound 7 binds to EBOV-GP at an early stage during EBOV infection. Preliminary Schrodinger SiteMap calculations, using a published EBOV-GP crystal structure in its prefusion conformation, suggested a hydrophobic pocket at or near the GP1 and GP2 interface as a suitable site for compound 7 binding. This prediction was supported by mutational analysis implying that residues Asn69, Leu70, Leu184, Ile185, Leu186, Lys190, and Lys191 are critical for the binding of compound 7 and its analogs with EBOV-GP. We hypothesize BAY 63-2521 in vivo that compound 7 binds to this hydrophobic pocket and as a consequence inhibits EBOV infection of cells, but the details of the mechanism remain to be determined. In summary, we have identified a novel series of benzodiazepine compounds that are suitable for optimization as potential inhibitors of filoviral infection.”
“Attractive faces have a special status, possibly because of evolutionary

reasons. We assessed the automaticity of facial attractiveness processing in a dual-task SBI-0206965 mouse paradigm manipulating the availability of cognitive resources to face processing by a primary tone task presented at varying stimulus onset asynchrony (SOA). In event-related brain potentials, attractive relative to neutral faces induced an increased posterior negativity from 260 ms onwards indicating enhanced stimulus encoding at the cortical level. Interestingly, effects of attractive faces on event-related brain potentials were most pronounced at high temporal overlap with the primary task (short stimulus onset asynchrony). This indicates that a shortage of cognitive resources may enhance the processing of attractive faces, revealing hard-wired processing biases of the human information processing system for evolutionarily prepared stimuli.

In vivo microdialysis was used to determine whether U50,488 (5 mg/kg) attenuates cocaine-induced dopamine overflow in the dorsal CPu on postnatal day (PD) 17 and PD 85. In the microinjection experiment, cocaine-induced stereotyped behaviors were assessed in adult and preweanling rats after bilateral infusions of vehicle or U50,488 (1.6 or 6.4 mu g per side) into the CPu. Results showed that U50,488 attenuated the cocaine-induced increases in CPu dopamine overflow on PD 85, while the same dose of U50,488 did not alter dopamine dialysate levels

on PD 17. Cocaine also increased stereotyped behaviors (repetitive motor movements, behavioral intensity scores, and discrete behaviors) at both ages, but learn more adult rats appeared to exhibit more intense stereotypic responses than the younger animals. Consistent with the microdialysis Entrectinib purchase findings, bilateral infusions of U50,488 into the dorsal CPu decreased the cocaine-induced stereotypies of adult rats, while

leaving the behaviors of preweanling rats unaffected. These results suggest that the neural mechanisms underlying kappa-opioid/dopamine interactions in the CPu are not fully mature during the preweanling period. This lack of functional maturity may explain why kappa-opioid receptor agonists frequently induce different behavioral effects in young and adult rats. (C) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.”
“Post weaning isolation-reared rats show deficits in learning and memory, which are also seen in many psychiatric disorders like schizophrenia. The present study utilized behavioral and electrophysiological tests 3-Methyladenine clinical trial to further characterize cognitive disorders in this rat model, and to explore possible neurobiological mechanisms associated with them. Isolation rearing was performed in male Wistar

rats from weaning for 8 weeks. Spatial memory and reversal learning were assessed using Morris water maze (MWM); synaptic plasticity was assessed by recording long-term potentiation (LTP) from thalamus to prefrontal cortex; and potassium ion channel currents were tested using the cerebrospinal fluid (CSF) of different groups in hippocampal slices by patch clamp. The results of MWM showed that isolation-reared rats performed worse in probe trials and memory retention tests. The LTP tests showed that the prefrontal cortical postsynaptic potential slopes were significantly lower in isolated rats than group housed ones. The patch clamp recording showed that the amplitudes of hippocampal voltage-dependent transient outward K(+) currents (I(A)) were enhanced, and the steady inactivation curve of I(A) was shifted towards positive potential by CSF of isolated rats.

The observed activities in seal neocortical slices support the notion that mammalian cortical networks intrinsically generate multiple states of activity that include oscillatory activity all the way down to < 0.1 Hz. This intrinsic neocortical excitability is an important contributor not only to sleep but

also to the default awake state of the neocortex. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.”
“A 78-year-old PF-4708671 man with end-stage renal disease and a right brachial-cephalic upper arm direct hemodialysis access presented with symptomatic central venous occlusion. The right brachiocephalic vein occlusion in this patient was refractory to wire traversal. Sharp recanalization of the central venous occlusion was done with an Outback LTD re-entry catheter (Cordis Corporation, a Johnson & Johnson Company, Miami, Fla). The track was balloon dilated and stented. When the conventional management options fail, this technique may be used to salvage a precious dialysis access and to relieve the patient from symptoms of central venous hypertension. (J Vasc Surg 2010;52:1038-40.)”
“Nickel (Ni2+) is a toxic metal that affects the function of several ionic channels. In the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor (NR), it causes activity LDK378 enhancement of the channels containing the NR2B subunit and voltage-independent

inhibition of those containing NR2A. Thus, it may represent a functional marker for the identification of NR native channel subunits. We investigated the effect of Ni2+ on spontaneous NR currents in cortical neurons, dissociated from 18-day rat embryos and maintained in culture for up to similar to 40 days. In whole-cell voltage-clamp at -60 mV, in a Mg2+-free bath containing the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione Ulixertinib (NBQX) (10 mu M), spontaneous currents were blocked by 10 mu M D(-)-2-Amino-5-phosphonopentanoic acid (APV) (10 mu M), and by NR2B antagonists, ifenprodil (10 mu M) or Ro25-6981 (Ro25, 1 mu M), indicating

that they are due to NRs containing predominantly the NR2B subunit. In the presence of Ni2+ (30 mu M) the amplitude and the frequency of spontaneous currents were increased and the decay time decreased. A higher dose (300 mu M) blocked all electrical activity. In current-clamp, Ni2+ (30 mu M) caused a similar to 5 mV reversible depolarization. The effect of Ni2+, as well as that of NR2B antagonists, was almost independent of days in vitro (DIV) in the range from 18 to 33 DIV. The electrical activity of the neuronal networks measured by microelectrode arrays (MEAs) was also affected by Ni2+, which caused a decrease in firing rate, but an increase in burst duration, while Ro25 (1-10 mu M) caused a decrease in both firing rate and burst duration.

Conclusions: Exposure to World Trade Center dust led to large declines in FEV(sub 1) for FDNY rescue workers during the first year. Overall, these declines were persistent, without recovery over the next 6 years,

leaving a substantial proportion of workers with abnormal lung function.

N Engl J Med 2010;362:1263-72.”
“RNA viruses within a host exist as dynamic distributions of closely related mutants and recombinant genomes. These closely related mutants and recombinant genomes, which are subjected to a continuous process of genetic variation, competition, and selection, THZ1 molecular weight act as a unit of selection, termed viral quasispecies. Characterization of mutant spectra within hosts is essential for understanding viral evolution and pathogenesis resulting from the cooperative behavior of viral mutants within viral quasispecies. Furthermore, a detailed analysis of viral variability within hosts is needed to design control strategies, because viral quasispecies are reservoirs of viral

variants that potentially can emerge with increased virulence or Selleck Dibutyryl-cAMP altered tropism. In this work, we report a detailed analysis of within-host viral populations in 13 field isolates of the bipartite Tomato chlorosis virus (ToCV) (genus Crinivirus, family Closteroviridae). The intraisolate genetic structure was analyzed based on sequencing data for 755 molecular clones distributed in four genomic regions within the RNA-dependent RNA polymerase (RNA1) and Hsp70h, CP, and CPm (RNA2) open reading frames. Our results showed that populations of ToCV within a host plant have a heterogeneous and complex genetic structure others similar to that described for animal and plant RNA viral quasispecies. Moreover, the structures of these populations clearly differ depending on the RNA segment considered, being more complex for RNA1 (encoding replication-associated proteins) than for

RNA2 (encoding encapsidation-, systemic-movement-, and insect transmission-relevant proteins). These results support the idea that, in multicomponent RNA viruses, function can generate profound differences in the genetic structures of the different genomic segments.”
“Background: There is no established standard chemotherapy for patients with locally advanced or metastatic biliary tract cancer. We initially conducted a randomized, phase 2 study involving 86 patients to compare cisplatin plus gemcitabine with gemcitabine alone. After we found an improvement in progression-free survival, the trial was extended to the phase 3 trial reported here.

Methods: We randomly assigned 410 patients with locally advanced or metastatic cholangiocarcinoma, gallbladder cancer, or ampullary cancer to receive either cisplatin (25 mg per square meter of body-surface area) followed by gemcitabine (1000 mg per square meter on days 1 and 8, every 3 weeks for eight cycles) or gemcitabine alone (1000 mg per square meter on days 1, 8, and 15, every 4 weeks for six cycles) for up to 24 weeks.

It should Pexidartinib purchase be noted that in the animals that received saline after training and tested following intra-amygdala administration of pilocarpine (0.125, 0.25 and 0.5 mu g/side) and those which received post-training morphine (7.5 mg/kg s.c.) and pre-test intra-amygdala microinjection of the same doses of pilocarpine, no significant change was observed in the step-through

latencies. On the other hand, pre-test intra-amygdala microinjection of a selective muscarinic acetylcholine receptor antagonist scopolamine (0.125 and 0.25 mu g/side) inhibited morphine-induced state-dependent memory retrieval. In addition, no significant changes were seen in memory retrieval of the animals trained before saline treatment and tested following intra-amygdala microinjection of the same doses of scopolamine (0.0625, 0.125 and 0.25 mu g/side). Bilateral microinjection of scopolamine into the amygdala reversed the pilocarpine-induced potentiation of the morphine response. In view of the known actions of the drugs used, the present data point to the involvement of amygdala muscarinic acetylcholine receptors in morphine-induced state-dependent memory retrieval. LY2090314 in vitro (C) 2009 IBRO. Published

by Elsevier Ltd. All rights reserved.”
“The BGLF4 protein kinase of Epstein-Barr virus (EBV) is a member of the conserved family of herpesvirus protein kinases which, to some extent, have a function similar to that of the cellular cyclin-dependent kinase in regulating multiple cellular and viral substrates. In a yeast two-hybrid screening assay, a splicing variant of interferon (IFN)

regulatory factor 3 (IRF3) was found to interact with the BGLF4 protein. This interaction was defined further by coimmunoprecipitation in transfected cells and glutathione Adenosine triphosphate S-transferase (GST) pull-down in vitro. Using reporter assays, we show that BGLF4 effectively suppresses the activities of the poly(I: C)-stimulated IFN-beta promoter and IRF3-responsive element. Moreover, BGLF4 represses the poly(I: C)stimulated expression of endogenous IFN-beta mRNA and the phosphorylation of STAT1 at Tyr701. In searching for a possible mechanism, BGLF4 was shown not to affect the dimerization, nuclear translocation, or CBP recruitment of IRF3 upon poly(I: C) treatment. Notably, BGLF4 reduces the amount of active IRF3 recruited to the IRF3-responsive element containing the IFN-beta promoter region in a chromatin immunoprecipitation assay. BGLF4 phosphorylates GST-IRF3 in vitro, but Ser339-Pro340 phosphorylation-dependent, Pin1-mediated downregulation is not responsible for the repression. Most importantly, we found that three proline-dependent phosphorylation sites at Ser123, Ser173, and Thr180, which cluster in a region between the DNA binding and IRF association domains of IRF3, contribute additively to the BGLF4-mediated repression of IRF3(5D) transactivation activity.

(C) 2011 Elsevier Ltd. All rights reserved.”
“To discriminate between stable and dynamic protein-protein interactions, we propose a strategy in which cells with and without tagged bait are differentially labeled with stable isotope and combined prior to complex purification. Mass-spectrometric analysis of the purified complexes identifies stable and dynamic selleck chemical components as those derived exclusively from

the tagged cells and those from both cells, respectively. We successfully applied this strategy to analyze two yeast protein complexes, eIF2B-eIF2 and cyclin-Cdc28.”
“Psoriasis is strongly associated with streptococcal throat infection, and patients have increased occurrence of such infections. Psoriatic lesional T cells are oligoclonal, and T cells recognizing determinants common to streptococcal M-protein and keratin have been detected in patients’ blood. We propose that CD8(+) T cells in psoriatic epidermis respond mainly to such determinants, whereas CD4(+) T cells in the dermis preferentially recognize determinants on the streptococcal peptidoglycan that might itself act as an adjuvant. The streptococcal association might reflect Selleckchem Liproxstatin 1 the concurrence of superantigen production promoting skin-homing of tonsil T cells, M-protein mimicking keratin determinants, and adjuvant effects of the peptidoglycan. Accordingly, improvement of psoriasis after

tonsillectomy should be associated with fewer T cells that recognize keratin and streptococcal determinants.”
“This

work presents the application of a fading memory model to describe the behavior of contracted Selleckchem SNS-032 airway smooth muscle (ASM) for two biophysical cases: finite duration length steps and longitudinal sinusoidal oscillations. The model parameters were initially determined from literature data on transient step length change response and subsequently the model was applied to the two cases. Results were compared with previously published experimental data on ASM oscillations. The model confirms a trend observed in the experimental data which shows that: (i) the value of tissue length change is the most important factor to determine the degree of cross-bridge detachment and (ii) a strong correlation exists between increasing frequency and declining stiffness until a certain frequency (similar to 25 Hz) beyond which frequency dependence is negligible. Although the model was not intended to simulate biophysical events individually, the data could be explained by cross-bridge cycling rates. As the frequency increases, cross-bridge reattachment becomes less likely, until no further cross-bridge attachment is possible. (C) 2011 Elsevier Ltd. All rights reserved.”
“To analyze the association between fetal brain growth and late gestational blood serum cortisol in normal pregnancy.Blood total cortisol was quantified at delivery in 432 Chinese mother/child pairs.

Extensive miR profiling of the virus-infected and EBNA2-transfected B lymphoma cells revealed that oncomiR miR-21 is positively regulated by this viral protein. Conversely, Burkitt’s lymphoma (BL) cell lines infected with EBNA2 lacking P3HR1 strain did not show any increase in miR-21. EBNA2 increased

phosphorylation Dinaciclib in vitro of AKT and this was directly correlated with increased miR-21. In contrast, miR-146a was downregulated by EBNA2 in B lymphoma cells. Low miR-146a expression correlates with an elevated level of IRAK1 and type I interferon in EBNA2 transfectants. Taken together, the present data suggest that EBNA2 might contribute to EBV-induced B-cell transformation by altering miR expression and in particular by increasing oncomiR-like miR-21 and by affecting the antiviral responses of the innate immune system through downregulation of its key regulator miR-146a.”
“Many common potato tuber defects are difficult to elicidate because of the degree of genetic complexity involved making

systems biology approaches necessary Interaction between chlorogenic https://www.selleckchem.com/products/dorsomorphin-2hcl.html acid and iron is responsible for the darkening of potato tuber tissues upon heating termed after cooking darkening (ACD) To explore mechanisms of darkening severity in tuber tissues we have employed relative quantitative proteomics to discover differentially expressed proteins involved in ACD Tuber tissue samples were collected from a family of diploid clones which possess a highly segregated degree of the darkening Exploiting this segregation as well as the observation that darkening is more prevalent in the stem end of the tuber than the apical end three sample groups were formed (i) stem ends of three high Sitaxentan ACD clones, (ii) stem ends of three low ACD clones and (in) apical ends of three low ACD clones Protein samples were digested and differentially labeled using isotopic reductive methylation allowing for an orthogonal two way comparison of protein profiles of the sample groups

using 2 D LC MS/MS Using a cutoff fold change of 2 between the high and the low ACD sample groups 30 proteins showed a correlation with tissue darkening Overall we observed changes in relative protein abundance that showed an enhanced wound response program in high ACD tissues Among these proteins five proteins were further validated at the transcript level using qRT PCR These proteins may be incorporated into design strategies to create potato cultivars with low levels of ACD”
“In a previous in vitro study, we demonstrated the protective effects of a new drug, 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride (KHG26377), against glutamate-induced excitotoxicity in cultured glial cells. In this study, we explored the possible mechanisms underlying the neuroprotective and anti-inflammatory effects of this compound against glutamate-induced excitotoxicity in rat brain.

Cape-induced reduction of Hes-1 may be attributed to decreased interaction between NICD and RBP-JK whose levels were reduced concurrently. Hes-1 reduction may lead to decreased production of inflammatory cytokines and NO. It is concluded that NF-kappa B can modulate Notch-1 signaling. Both pathways operate synergistically for production of proinflammatory cytokines and NO

in activated microglia. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.”
“Accumulation of connective tissue is a typical feature of chronic liver diseases. Decorin, a small leucine-rich proteoglycan, regulates collagen fibrillogenesis during development, and by directly blocking the bioactivity of transforming growth factor-beta 1 (TGF beta 1), it exerts a protective effect against fibrosis. However, no in vivo investigations on the role selleck chemicals llc of decorin in liver have been performed

before. In this study we used decorin-null (Dcn-/-) mice to establish the role of decorin in experimental liver fibrosis and repair. Not only the extent of experimentally induced liver fibrosis was more severe in Dcn-/- animals, but also the healing process was significantly delayed vis-a-vis wild-type mice. Collagen I, III, and IV mRNA levels in Dcn-/- livers were higher than those of wild-type livers only in the first 2 months, but no difference was observed after 4 months of fibrosis induction, suggesting that the elevation of these proteins reflects a specific impairment of their degradation. Gelatinase assays confirmed this hypothesis as we found decreased MMP-2 and MMP-9 activity and higher expression of TIMP-1 and PAI-1 mRNA selleck selleckchem in Dcn-/- livers. In contrast, at the end of the recovery phase increased production rather than impaired degradation was found to be responsible for the excessive connective tissue deposition in livers of Dcn-/- mice. Higher expression of TGF beta 1-inducible early responsive gene in

decorin-null livers indicated enhanced bioactivity of TGF beta 1 known to upregulate TIMP-1 and PAI-1 as well. Moreover, two main axes of TGF beta 1-evoked signaling pathways were affected by decorin deficiency, namely the Erk1/2 and Smad3 were activated in Dcn-/- samples, whereas no significant difference in phospho-Smad2 was observed between mice with different genotypes. Collectively, our results indicate that the lack of decorin favors the development of hepatic fibrosis and attenuates its subsequent healing process at least in part by affecting the bioactivity of TGF beta 1. Laboratory Investigation (2011) 91, 439-451; doi: 10.1038/labinvest.2010.172; published online 18 October 2010″
“Brain-derived neurotrophic factor (BDNF) promotes synaptic plasticity via an enhancement in expression of specific synaptic proteins. Recent results suggest that the neuronal monocarboxylate transporter MCT2 is a postsynaptic protein critically involved in synaptic plasticity and long-term memory.

(C) 2009 Elsevier Ltd. All rights reserved.”
“The goal of the present study was to demonstrate that declarative and non-declarative knowledge acquired in an incidental sequence learning task contributes differentially to memory retrieval and leads to dissociable ERP signatures in a recognition memory task. For this purpose, participants performed a sequence learning task and were classified as verbalizers, partial verbalizers, or nonverbalizers according to their ability to verbally report the systematic response

sequence. Thereafter, ERPs were recorded in a recognition memory task time-locked to sequence triplets that were either part of the previously learned sequence or not. Although all three groups executed old sequence triplets faster than new triplets in the recognition memory Selleckchem 5-Fluoracil task, qualitatively distinct ERP patterns were found for participants with and AZD9291 supplier without reportable knowledge. Verbalizers and, to a lesser extent, partial verbalizers showed

an ERP correlate of recollection for parts of the incidentally learned sequence. In contrast, nonverbalizers showed a different ERP effect with a reverse polarity that might reflect priming. This indicates that an ensemble of qualitatively different processes is at work when declarative and non-declarative sequence knowledge is retrieved. By this, our findings favor a multiple-systems view postulating that explicit and implicit learning are supported by different and functionally independent systems. (C) 2010 Elsevier Ltd. All rights reserved.”
“Many birds exhibit considerable phenotypic

flexibility in metabolism to maintain thermoregulation or to conserve energy. This flexibility usually includes seasonal variation in metabolic rate. Seasonal changes in physiology and behavior of birds are considered to be a part of their adaptive strategy for survival and reproductive success. House Sparrows (Passer domesticus) are small passerines from Europe that have been successfully introduced to many parts of the world, and thus may be expected to exhibit high phenotypic flexibility in metabolic rate. Mass specific Resting Metabolic Rate (RMR) and Basal Metabolic Rate (BMR) were significantly higher in winter Cytoskeletal Signaling inhibitor compared with summer, although there was no significant difference between body mass in summer and winter. A similar, narrow thermal neutral zone (25-28 degrees C) was observed in both seasons. Winter elevation of metabolic rate in House Sparrows was presumably related to metabolic or morphological adjustments to meet the extra energy demands of cold winters. Overall, House Sparrows showed seasonal metabolic acclimatization similar to other temperate wintering passerines. The improved cold tolerance was associated with a significant increase in VO(2) in winter relative to summer. In addition, some summer birds died at 5 degrees C, whereas winter birds did not, further showing seasonal variation in cold tolerance.