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Objective Neural cell adhesion molecule L1CAM (L1) is involved in neuroprotection. To investigate a possible neuroprotective effect of L1 during ischemia, we determined whether blocking L1 with an antagonistic antibody would worsen the outcome of focal cerebral ischemia-reperfusion and increase blood-brain barrier (BBB) disruption. Methods Transient middle cerebral artery occlusion (MCAO) was performed in anesthetized rats. Five µg of antagonistic mouse IgG monoclonal L1 antibody 324 or non-immune control mouse IgG was applied on the ischemic-reperfused cortex during one hour of MCAO and two hours of reperfusion. At two hours of reperfusion, BBB permeability, size of infarct using tetrazolium staining, number of TUNEL-labeled apoptotic cells, and immunohistochemistry for expression of PTEN and p53 were studied. Results The antagonistic L1 antibody 324 increased the percentage of cortical infarct area (+36%), but did not affect BBB permeability in the ischemic-reperfused cortex. The antagonistic L1 antibody increased number of apoptotic neurons and p53 expression, but decreased PTEN expression. Conclusion Functional antagonism of L1 increases infarct size by increasing numbers of apoptotic neurons without affecting BBB permeability during the early stage of cerebral ischemia-reperfusion. Our data suggest that L1 affects primarily the brain parenchyma rather than BBB during early stages of cerebral ischemia-reperfusion and that endogenous brain L1 may be neuroprotective.

The remarkable biocompatibility and supreme physical properties of nanostructured TiO2 have promised itself a strong future for biomedical applications. The present study reported a theoretical study on the adsorption of rutile TiO2 (110) nanosheet for DNA nucleobases using first-principles calculations. The calculations of the binding energy and work function demonstrate that the TiO2 nanosheet has remarkable adsorption strength to the DNA nucleobases, being more than 20 times larger than that of graphene and its derivatives. Further electronic band structure and density of state calculations elucidate the interaction mechanisms, which originate from dramatically reduced energy levels and strong hybridization of the 2p orbital of C, N and/or O with 3d orbital of Ti atoms near the Fermi level. The study directs a promising material at applications in DNA sensors and sequencers.

The spinel group is a growing family of materials with general formulation AB2X4 (the X anion typically being a chalcogen like O and S) with many advanced applications for energy. At the time being, the spinel zinc gallate (ZnGa2O4) arguably is the ternary ultra-wide bandgap bipolar oxide semiconductor with the largest bandgap (∼5eV), making this material very promising for implementations in deep UV optoelectronics and ultra-high power electronics. In this work, we further demonstrate that, exploiting the rich cation coordination possibilities of the spinel chemistry, the ZnGa2O4 intrinsic conductivity (and its polarity) can be controlled well over 10 orders of magnitude. p-type and n-type ZnGa2O4 epilayers can be grown by tuning the pressure, oxygen flow and cation precursors ratio during metal-organic chemical vapor deposition. A relatively deep acceptor level can be achieved by promoting antisites (ZnGa) defects, while up to a (n > 1019 cm−3) donor concentration is obtained due to the hybridization of the Zn–O orbitals in the samples grown in Zn-rich conditions. Electrical transport, atomic and optical spectroscopy reveal a free hole conduction (at high temperature) for p-ZnGa2O4 while for n-ZnGa2O4 a (Mott) variable range hopping (VRH) and negative magnetoresistance phenomena take place, originated from “self-impurity” band located at Ev+ ∼3.4 eV. Among arising ultra-wide bandgap semiconductors, spinel ZnGa2O4 exhibit unique self-doping capability thus extending its application at the very frontier of current energy optoelectronics., This study was financially supported by Ministry of Science and Technology, Taiwan (MOST 109-2622-E-009-033, 108-2618-E-009-031, 109-2224-E-009-002, 109-2634-F-009-028, 109-2221-E-009-143-MY3, 108-2628-E-002-010-MY3) and the Higher Education SPROUT Project-Center for Emergent Functional Matter Science of National Yang Ming Chiao Tung University.

To address concerns among members of the Canadian Society of Soil Science (CSSS) regarding the discipline’s capacity to train new soil professionals, specifically in pedology and field skills, members of the CSSS’s soil education and pedology committees have proposed to develop a pedology field school. To aid in the selection of learning outcomes that are relevant to professional practice, an online survey was sent to Canadian soil professionals within private industry and governmental organizations. Professional feedback was also requested regarding the creation of a web-based national soil education resource and the certification of soil pedological skills. According to the survey results, the quality of new graduates’ pedology and field skills was perceived as poor. Certain soil field skills and knowledge were thought to be either completely absent from the current Canadian curriculum (e.g., spatial variability of soil processes), or not well mastered by graduates (e.g., interpreting soil survey reports). Important learning outcomes were identified, such as interpreting soil survey information, soil mapping, and soil-landscape classification with soil description–classification and soil genesis content needed as a refresher. Taking into consideration existing regional field schools, we recommend that the CSSS co-create, where needed, and coordinate, where they already exist, regional pedology field schools throughout Canada. We also propose that the CSSS develop a national pedology certification and a web-based soil education resource. Also, further study is necessary to shed light on the contribution of non-disciplinary graduates to the professional practice and the impact this has on the perception of soil education in Canada.

Introduction Mir-146a-5p has been widely recognized as a critical regulatory element in the immune response. However, recent studies have shown that miR-146a-5p may also be involved in the development of Alzheimer disease (AD). Regrettably, the related mechanisms are poorly understood. Here, we investigated the effects of miR-146a in mice models and SH-SY5Y cells treated with amyloid β (Aβ)1–42. Methods To create a model of AD, SH-SY5Y cells were treated with Aβ1–42 and mice received intracerebroventricular injections of Aβ1–42. Then, the transcriptional levels of miR-146a were estimated by real-time PCR. We transiently transfected the miR-146a-5p mimic/inhibitor into cells and mice to study the role of miR-146a. The role of signaling pathways including p38 and reactive oxygen species (ROS) was studied by using specific inhibitors. Aβ and amyloid-beta precursor protein (APP)levels were measured by immunoblotting. Furthermore, Aβ expression was analyzed by immunofluorescence and histochemical examinations. Results Aβ1–42-stimulated SH-SY5Y cells displayed increased transcriptional levels of miR-146a and APP. Moreover, the p38 MAPK signaling pathway and ROS production were activated upon stimulation with a miR-146a-5p mimic. However, treatment with a miR-146a-5p inhibitor decreased the levels of APP, ROS, and p-p38 MAPK. A similar phenomenon was also observed in the animals treated with Aβ1–42, in which miR-146a upregulation increased the expression of Aβ, p-p38, and ROS, while the inhibition of miR-146a had the opposite effect. This suggests that miR-146a increases Aβ deposition and ROS accumulation via the p-p38 signaling pathway. Conclusions Our research demonstrates that miR-146a-5pa increases Aβ deposition by triggering oxidative stress through activation of MAPK signaling.

Throughout this paper, all groups are finite. $${\sigma =\{\sigma_{i}\mid i\in I \}}$$ is some partition of the set of all primes $${\mathbb{P}}$$ , and $${\sigma (n)= \{\sigma _{i}\mid \sigma _{i}\cap \pi (n)\ne \emptyset \}}$$ for any $${n\in \mathbb{N}}$$ . The natural numbers n and m are called $${\sigma}$$ -coprime if $${\sigma (n)\cap \sigma (m)=\emptyset}$$ . Let t > 1 be a natural number and let $${\mathfrak{F}}$$ be a class of groups. Then we say that $${\mathfrak{F}}$$ is $${\Gamma_{t}^{\sigma}}$$ -closed (respectively weakly $${\Gamma_{t}^{\sigma}}$$ -closed) provided $${\mathfrak{F}}$$ contains each finite group G which satisfies the following conditions: We study properties and some applications of (weakly) $${\Gamma_{t}^{\sigma}}$$ -closed classes of finite groups.

Background We investigated whether exogenous lysophosphatidic acid (LPA), a phospholipid extracellular signaling molecule, would increase infarct size and blood-brain barrier (BBB) disruption during the early stage of cerebral ischemia-reperfusion, and whether it works through Akt-mTOR-S6K1 intracellular signaling. Material and methods Rats were given either vehicle or LPA 1 mg/kg iv three times during reperfusion after one hour of middle cerebral artery (MCA) occlusion. In another group, prior to administration of LPA, 30 mg/kg of PF-4708671, an S6K1 inhibitor, was injected. After one hour of MCA occlusion and two hours of reperfusion the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid and the volume of 3H-dextran distribution were determined to measure the degree of BBB disruption. At the same time, the size of infarct was determined and western blot analysis was performed to determine the levels of phosphorylated Akt (p-Akt) and phosphorylated S6 (pS6). Results LPA increased the Ki in the ischemic-reperfused cortex (+43%) when compared with Control rats and PF-4708671 pretreatment prevented the increase of Ki by LPA. LPA increased the percentage of cortical infarct out of total cortical area (+36%) and PF-4708671 pretreatment prevented the increase of the infarct size. Exogenous LPA did not significantly change the levels of p-Akt as well as pS6 in the ischemic-reperfused cortex. Conclusion Our data demonstrate that the increase in BBB disruption could be one of the reasons of the increased infarct size by LPA. S6K1 may not be the major target of LPA. A decrease of LPA during early cerebral ischemia-reperfusion might be beneficial for neuronal survival.

There have been reports that activation of Akt may provide neuroprotection after cerebral ischemia-reperfusion. We tested the hypothesis that activation of Akt would decrease infarct size and improve microregional O2 supply/consumption balance after cerebral ischemia-reperfusion. This hypothesis was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without SC-79 (Akt activator, 0.05 mg/kg, three doses). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small vessel (20-60 μm diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. Akt phosphorylation was determined by Western blot. There were no significant hemodynamic or blood gas differences between groups. The control ischemic-reperfused cortex had a similar O2 consumption, but lower blood flow and higher O2 extraction compared to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O2 saturation (42 of 80 veins with O2 saturation below 50%). SC-79 did not significantly affect cerebral O2 consumption, but significantly improved O2 supply/consumption balance in the reperfused area (18 of 80 veins with O2 saturation below 50%). This was associated with a reduced cortical infarct size (13.3 ± 0.5% control vs 6.7 ± 0.3% SC-79). In control, Akt phosphorylation was elevated at 2 h after ischemia. With SC-79, Akt was activated at 15 min but not at 2 h in the ischemic reperfused area. These results suggest that early Akt activation is important for not only cell survival, but also for the control of local oxygen balance after cerebral ischemia-reperfusion.

Blood-brain barrier (BBB) disruption is one of the most important pathological changes following cerebral ischemia-reperfusion. We tested whether inhibition of the serum and glucocorticoid regulated kinase 1 (SGK1) would decrease BBB disruption and contribute to decreasing infarct size in the first few hours of cerebral ischemia-reperfusion within the thrombolysis therapy time window. After transient middle cerebral artery occlusion (MCAO), an SGK1 inhibitor GSK650394, or vehicle was administered into the lateral ventricle of rats. After one hour of MCAO and two hours of reperfusion, we determined BBB disruption using the transfer coefficient (K(i)) of (14)C-α-aminoisobutyric acid, and also determined infarct size, phosphorylation of NDRG1, and MMP2 protein level. Ischemia-reperfusion increased (+34%, p < 0.05) and GSK650394 decreased (−25%, p < 0.05) the K(i) in the ischemic-reperfused cortex. GSK650394 decreased the percentage of cortical infarct (−31%, p < 0.001). At the same time GSK650394 reduced NDRG1 phosphorylation and MMP2 protein level in the ischemic-reperfused cortex suggesting that SGK1 was inhibited by GSK650394 and that lower MMP2 could be one of the mechanisms of decreased BBB disruption. Collectively our data suggest that GSK650394 could be neuroprotective and one of the mechanisms of the neuroprotection could be decreased BBB disruption. SGK1 inhibition within the thrombolysis therapy time window might reduce cerebral ischemia-reperfusion injury.

Which the actual critical electrical field of the ultra-wide bandgap semiconductor β-Ga2O3 is? Even that it is usual to find in the literature a given value for the critical field of wide and ultra-wide semiconductors such as SiC (3 MV/cm), GaN (3.3 MV/cm), β-Ga2O3 (~8 MV/cm) and diamond (10 MV/cm), this value actually depends on intrinsic and extrinsic factors such as the bandgap energy, material residual impurities or introduced dopants. Indeed, it is well known from 1950's that reducing the residual doping (NB) of the semiconductor layer increases the breakdown voltage capability of a semiconductor media (e.g. as 𝑁𝑁𝐵𝐵 −3⁄4 by using the Fulop's approximation for an abrupt junction). A key limitation is, therefore, the residual donor/acceptor concentration generally found in these materials. Here, we report that doping with amphoteric Zinc a p-type β-Ga2O3 thin films shortens free carrier mean free path (0.37 nm), resulting in the ultra-high critical electrical field of 13.2 MV/cm. Therefore, the critical breakdown field can be, at least, four times larger for the emerging Ga2O3 power semiconductor as compared to SiC and GaN. We further explain these wide-reaching experimental facts by using theoretical approaches based on the impact ionization microscopic theory and thermodynamic calculations., Hagar Mohammed would like to acknowledge Cultural Affairs and Massion Sector, Egyptian Ministry for Higher Education for her fellowship giving possibility work in France. APT acknowledges Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under contract ENE2015-74275-JIN. The ICN2 is funded by the CERCA programme/Generalitat de Catalunya and by the Severo Ochoa programme of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grant no. SEV-2017-0706).

Background: Lysophosphatidic acid (LPA) is a small phospholipid-signaling molecule, which can alter responses to stress in the central nervous system. Objective: We hypothesized that exogenous LPA would increase the size of infarct and reduce microregional O2 supply/consumption balance after cerebral ischemia-reperfusion. Methods: This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without LPA (1 mg/kg, at 30, 60, and 90 min after reperfusion). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small-vessel (20–60 µm in diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. Results: There were no significant hemodynamic or arterial blood gas differences between groups. The control ischemic-reperfused cortex had a similar O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O2 saturation (43 of 80 veins with O2 saturation below 50%). LPA did not significantly alter cerebral blood flow, but it did significantly increase O2 extraction and consumption of the ischemic-reperfused region. It also significantly increased the number of small veins with low O2 saturations in the reperfused region (76 of 80 veins with O2 saturation below 50%). This was associated with a significantly increased cortical infarct size after LPA administration (11.4 ± 0.5% control vs. 16.4 ± 0.6% LPA). Conclusion: This suggests that LPA reduces cell survival and that it is associated with an increase in the number of small microregions with reduced local oxygen balance after cerebral ischemia-reperfusion.

Renal cell carcinoma (RCC) is the most common malignant tumor of the kidney. In this study, we investigated the role of miR-346 in RCC cells under hypoxia. OS-RC-2 and 786-O cells were cultured in 1% O2 or normal oxygen. Cell proliferation, migration, and invasion abilities were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, transwell migration, and invasion assays, respectively. Quantitative real-time PCR (qRT-PCR) was performed to detect the expression of miR-346 and N-myc downstream-regulated gene 2 (NDRG2). Then bioinformatics analysis, dual-luciferase reporter assay, and RNA immunoprecipitation were carried out to determine the relationship between miR-346 and NDRG2. The protein expression of NDRG2 was detected by western blot assay. Hypoxia promoted cell proliferation, migration, and invasion in OS-RC-2 and 786-O cells. Meanwhile, we found that miR-346 was upregulated in RCC cells under hypoxia as relative to normoxia. miR-346 deletion could decrease the viability, migration, and invasion abilities of RCC cells under hypoxia. Besides, our data demonstrated that NDRG2 was a target gene of miR-346. The expression of NDRG2 in OS-RC-2 and 786-O cells was lower under hypoxia than under normal oxygen conditions. Moreover, NDRG2 overexpression could inhibit cell proliferation, migration, and invasion in RCC cells under hypoxia. And NDRG2 silencing reversed the inhibitory effects of the miR-346 inhibitor on the viability, migration, and invasion abilities of RCC cells in hypoxia conditions. miR-346 promoted the viability, migration, and invasion of RCC cells under hypoxia by targeting NDRG2.

—Activation of the mammalian target of rapamycin (mTOR) leads to cell growth and survival. We tested the hypothesis that inhibition of mTOR would increase infarct size and decrease microregional O2 supply/consumption balance after cerebral ischemia–reperfusion. This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with and without rapamycin (20 mg/kg once daily for two days prior to ischemia). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small-vessel arterial and venous oxygen saturations were determined microspectrophotometrically. The control ischemic-reperfused cortex had a similar blood flow and O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex. Rapamycin significantly increased cerebral O2 consumption and further reduced O2 supply/consumption balance in the reperfused area. This was associated with an increased cortical infarct size (13.5 ± 0.8% control vs. 21.5 ± 0.9% rapamycin). We also found that ischemia–reperfusion increased AKT and S6K1 phosphorylation, while rapamycin decreased this phosphorylation in both the control and ischemic-reperfused cortex. This suggests that mTOR is important for not only cell survival, but also for the control of oxygen balance after cerebral ischemia–reperfusion.

The steel arches with weld H-shaped sections are frequently used in various engineering structures. The welding procedure will produce residual stress, which affects the stability of the arches. This paper presented a numerical model to explore the influence of welding residual stress on the stability behavior of the steel arch. Then, the buckling load and structural deformation of the steel arch under uniform load were obtained through the static analysis, and the stability performance of entire structure was discussed. Furthermore, in order to compare the mechanical properties of the arch simulated by different elements, the shell element and beam element were used respectively in the finite element modal to obtain ultimate bulking load of the structure with the same section. It is concluded that the existence of welding residual stress reduced the ultimate bearing capacity of steel arch under uniform load.

Background: We tested the hypothesis that inhibition of p70 ribosomal S6 kinase (S6K1) would decrease infarct size and improve microregional O2 supply/consumption balance after cerebral ischemia-reperfusion. Methods: This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 hour and reperfusion for 2 hours with or without PF-4708671 (S6K1 inhibitor, 75 mg/kg, 15 minutes after blockade). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small vessel (20-60 μm diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. Results: There were no significant hemodynamic or arterial blood gas differences between groups. The control ischemic-reperfused cortex had a similar O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O2 saturation (23 of 80 veins with O2 saturation below 45%). PF-4708671 did not significantly alter cerebral blood flow or O2 consumption. However, it significantly reduced the number of small veins with low O2 saturations in the reperfused region (6 of 80 veins with O2 saturation below 45%). This was associated with a significantly reduced cortical infarct size after S6K1 inhibition (12.9 ± .8% control versus 6.6 ± .3% PF-4708671). Conclusion: This suggests that S6K1 inhibition is important for cell survival and that it reduces the number of small microregions with reduced local oxygen balance after cerebral ischemia-reperfusion.

It is not clear whether inhibition of p70 ribosomal S6 kinase 1 (S6K1) is neuroprotective in cerebral ischemia-reperfusion. Decreasing blood-brain barrier (BBB) disruption has been associated with a better neuronal outcome in cerebral ischemia. We hypothesized that inhibition of S6K1 would decrease BBB disruption and infarct size in the early stage of cerebral ischemia-reperfusion. Middle cerebral artery occlusion (MCAO) was performed in rats under isoflurane anesthesia with controlled ventilation. 75 mg/kg of PF-4708671, an S6K1 inhibitor, was administered intraperitoneally 15 min after MCAO. After 1 h of MCAO and 2 h of reperfusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid and the volume of 3H-dextran distribution were determined to assess the degree of BBB disruption. At the same time point, phosphorylated Rictor (pT1135) and the infarct size were measured to evaluate S6K1 activity. In the PF-4708671 treated rats, the Ki of the ischemic-reperfused cortex was lower than the untreated rats (−22%, P Our data demonstrate that PF-4708671 decreased the size of the cortical infarct in the ischemic-reperfused cortex with a decrease in BBB disruption suggesting that inhibition of S6K1 may induce neuronal survival in early cerebral ischemia-reperfusion and that a decrease of BBB disruption could be one of the contributing factors.

As a key instrument for resistance metrology, cryogenic current comparator (CCC) is now widely used in national labs. In order to further improve the performances of CCC and make it easy operate, NIM has made some improvements, which are developing digital controller to replace conventional analog circuit and designing a zero boil-off cryogenic container specially served for CCC. Pre-experiments show that the new digital controller performs a better operability and the zero boil-off cryogenic container has a significant convenience for CCC cryo maintenance.

Activation of Akt has been suggested to produce neuronal protection in cerebral ischemia. Decreasing blood-brain barrier (BBB) disruption has been associated with a better neuronal outcome in cerebral ischemia. We hypothesized that activation of Akt would decrease BBB disruption and contribute to decreasing the size of infarct in the early stage of cerebral ischemia-reperfusion within the therapeutic window. Transient middle cerebral artery occlusion (MCAO) was performed in rats under isoflurane anesthesia with controlled ventilation. Rats were treated with SC79 (a selective Akt activator which is cell and BBB permeable) 0.05 mg/kg × 3 i.p. or vehicle i.p. perioperatively. After one hour of MCAO and two hours of reperfusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid (14C-AIB, molecular weight 104 Da) and the volume of 3H-dextran (molecular weight 70,000 Da) distribution were determined to measure the degree of BBB disruption. At the same time point, the size of infarction was determined using tetrazolium staining. In an additional group of rats, a higher dose of SC79 (0.5 mg/kg × 3) was administered to determine the size of infarct. Administration of SC79 increased the Ki in the ischemic-reperfused cortex (IR-C, +32%, p < 0.05) as well as in the contralateral cortex (CC, +35%, p < 0.05) when compared with the untreated animals with MCAO/reperfusion. The volume of dextran distribution was not significantly changed by SC79. SC79 treatment significantly produced a decrease in the percentage of cortical infarct out of total cortical area (12.7 ± 1.7% vs 6.9 ± 0.9%, p < 0.001). Increasing the dose of SC79 by ten times did not significantly affect the size of cortical infarct. Contrary to our hypothesis, our data demonstrated that SC79 decreased the size of the infarct in the ischemic-reperfused cortex despite an increase in BBB disruption. Our data suggest the importance of activation of Akt for neuronal survival in the early stage of cerebral ischemia-reperfusion within the therapeutic window and that the mechanism of neuroprotection may not be related to the BBB effects of SC79.

Tuberous sclerosis (TSC) is associated with autism spectrum disorders and has been linked to metabolic dysfunction and unrestrained signaling of the mammalian target of rapamycin (mTOR). Inhibition of mTOR by rapamycin can mitigate some of the phenotypic abnormalities associated with TSC and autism, but whether this is due to the mTOR-related function in energy metabolism remains to be elucidated. In young Eker rats, an animal model of TSC and autism, which harbors a germ line heterozygous Tsc2 mutation, we previously reported that cerebral oxygen consumption was pronouncedly elevated. Young (4 weeks) male control Long-Evans and Eker rats were divided into control and rapamycin-treated (20 mg/kg once daily for 2 days) animals. Cerebral regional blood flow ((14)C-iodoantipyrine) and O2 consumption (cryomicrospectrophotometry) were determined in isoflurane-anesthetized rats. We found significantly increased basal O2 consumption in the cortex (8.7 ± 1.5 ml O2/min/100 g Eker vs. 2.7 ± 0.2 control), hippocampus, pons and cerebellum. Regional cerebral blood flow and cerebral O2 extractions were also elevated in all brain regions. Rapamycin had no significant effect on O2 consumption in any brain region of the control rats, but significantly reduced consumption in the cortex (4.1 ± 0.3) and all other examined regions of the Eker rats. Phosphorylation of mTOR and S6K1 was similar in the two groups and equally reduced by rapamycin. Thus, a rapamycin-sensitive, mTOR-dependent but S6K1-independent, signal led to enhanced oxidative metabolism in the Eker brain. We found decreased Akt phosphorylation in Eker but not Long-Evans rat brains, suggesting that this may be related to the increased cerebral O2 consumption in the Eker rat. Our findings suggest that rapamycin targeting of Akt to restore normal cerebral metabolism could have therapeutic potential in tuberous sclerosis and autism.

Most anesthetics affect cerebral blood flow and metabolism. We compared microregional O2 balance in cerebral ischemia-reperfusion during pentobarbital and isoflurane anesthesia.After 1 hour of middle cerebral artery occlusion and a 2-hour reperfusion under isoflurane (1.4%, n = 14) or pentobarbital (50 mg/kg, n = 14) anesthesia in rats, regional cerebral blood flow using (14)C-iodoantipyrine autoradiography, microregional arterial and venous O2 saturation (20-60 μm in diameter) using cryomicrospectrophotometry, and the size of cortical infarct were determined.Ischemia-reperfusion decreased the average cortical venous O2 saturation in both pentobarbital and isoflurane groups (P .0001), which was higher (P .05) with pentobarbital despite a similar average regional cerebral blood flow and O2 consumption. The heterogeneity of venous O2 saturation reported as a coefficient of variation (100 × standard deviation/mean) was smaller (P .005) with pentobarbital than that with isoflurane (7.5 versus 16.1). The number of veins with low venous O2 saturation (50%) was smaller (P .005) with pentobarbital (5 of 80 versus 24 of 80). The percentage of cortical infarct in total cortex was smaller with pentobarbital (5.2 ± 2.5% versus 12.3 ± 2.6%, P .001).In the cerebral ischemic-reperfused cortex, the average venous O2 saturation was higher, and its heterogeneity and the number of veins with low O2 saturation were smaller under pentobarbital than isoflurane anesthesia. This improvement in microregional O2 balance with pentobarbital was accompanied by the reduced cortical infarct. Our data suggest that the neurologic outcome could vary during cerebral ischemia-reperfusion depending on the anesthetics used.

Diabetes causes functional and structural changes in blood-brain barrier (BBB). The mammalian target of rapamycin (mTOR) has been associated with glucose metabolism, diabetes, and altering BBB permeability. Since there is only a narrow therapeutic window (3h) for stroke victims, it is important to investigate BBB disruption in the early stage of cerebral ischemia. We compared the degree of BBB disruption in diabetic and in control rats at two hours of reperfusion after one hour of middle cerebral artery (MCA) occlusion with or without inhibition of mTOR. Two weeks after streptozotocin ip to induce diabetes, MCA occlusion was performed. In half of the rats, an mTOR inhibitor, rapamycin was given for 2days before MCA occlusion. After one hour of MCA occlusion and two hours of the reperfusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid was determined to quantify degree of BBB disruption. Ischemia-reperfusion increased the Ki in the control animals. Streptozotocin increased the Ki in the ischemic-reperfused (IR-C, +22%) as well as in the contralateral cortex (CC, +40%). Rapamycin decreased the Ki in the IR-C (-32%) as well as in the CC (-26%) in the control rats. However, rapamycin did not affect Ki in the IR-C or in the CC in the diabetic rats. Our data demonstrated a greater BBB disruption in diabetes in the ischemic as well as non-ischemic cortex even in the early stage of cerebral ischemia-reperfusion and that acute administration of rapamycin did not significantly affect BBB permeability in diabetes. From our quantitative analysis of BBB disruption, the vulnerability of BBB in diabetes has been emphasized in the early stage of cerebral ischemia-reperfusion and a less important role of the mTOR pathway is suggested in altering BBB permeability in diabetes.

Understanding changes in soil N cycling with stand development is critical for forest management as tree growth is affected by soil N availability. The aim of this study was to evaluate the changes in soil N availability and loss with stand development in trembling aspen (Populus tremuloides Michx.) and jack pine (Pinus banksiana Lamb.) in northeastern Alberta, Canada. Soil inorganic N availability (measured as N supply rate) and foliar N chemistry (N concentration and δ15N) in trembling aspen stands ranged from 52 to 70 years old (n = 7) and jack pine stands 43 to 78 years old (n = 8) were investigated in 2008 and 2009. The relationships among the ratios of NO3 --N to total inorganic N (NO3 --N/TIN), foliar N concentration, and foliar δ15N with stand age were also explored by regression analyses. Total inorganic N supply rates did not systematically change with stand age across stand types, soil layers and measurement periods; whereas NO3 --N/TIN showed a decreasing tendency with stand age, suggesting that nitrification and associated N loss potential became smaller in older stands with greater limitation in soil N availability. Foliar δ15N decreased with stand age from −1.7 to −4.7‰ for aspen and from −4.1 to −7.1‰ for jack pine, and there were positive correlations between foliar δ15N and soil NO3 --N/TIN, suggesting that decreased soil N loss led to less 15N-depletion in the inorganic N available for tree uptake in older stands. However, foliar N concentration did not significantly change with stand age, suggesting that there were other N sources such as organic N in the forest floor, in addition to the inorganic N, available for plant uptake. Our results suggest that soil inorganic N availability became more limited as stand age increased. In addition, the ratio of NO3 --N/TIN and its relationship with foliar δ15N indicated decreased soil N loss potential and shifted N sources with stand age in boreal forests that are typically N-limited. Our study demonstrated that declining nitrification with increasing stand age might be one of the mechanisms mediating N-limitation in the studied boreal forests.

Soil pH is among the major environmental factors affecting plant growth. Although the optimum range of soil pH for growth and the tolerance of pH extremes widely vary among plant species, the pH tolerance mechanisms in plants are still poorly understood. In this study, possible mechanisms were examined to explain the differences in tolerance of boreal plants to root zone pH. In the controlled-environment solution culture experiments, we compared growth, physiological parameters and tissue nutrient concentrations in aspen, white spruce and tamarack seedlings that were subjected to 8 weeks of root zone pH treatments ranging from 5.0 to 9.0. The pH treatments had little effect on dry weights and net photosynthesis in white spruce seedlings despite reductions in transpiration rates at higher pH levels. In aspen and tamarack, both the growth and physiological parameters significantly decreased at pH higher than 6.0. The chlorosis of young tissues in aspen and tamarack was associated with the reductions in foliar concentrations of several of the examined essential nutrients including Fe and Mn. Although the plants varied in their ability to deliver essential nutrients to growing leaves, there was no direct correlation between tissue nutrient concentrations, chlorophyll concentrations and plant growth. The results also demonstrated strong inhibition of transpiration rates by high pH. The results suggest that high root zone pH can upset water balance in pH sensitive species including aspen. Although the uptake and assimilation of essential elements such as Fe and Mn contribute to plant tolerance of high soil pH, we did not observe a direct relationship between growth and foliar nutrient concentrations to account for the observed differences in growth.

Hyperosmolar blood-brain barrier (BBB) disruption has been reported to increase cerebral O2 consumption. This study was performed to test whether blockade of N-methyl-d-aspartate (NMDA) receptor would affect cerebral O2 consumption during hyperosmolar BBB disruption. A competitive NMDA receptor antagonist CGS-19755 10mg/kg was injected iv 15min before intracarotid infusion of 25% mannitol. Twelve min after BBB disruption, the BBB transfer coefficient (Ki) of (14)C-α-aminoisobutyric acid ((14)C-AIB) was measured. Regional cerebral blood flow (rCBF), regional arteriolar and venular O2 saturation (SaO2 and SvO2 respectively), and O2 consumption were determined using (14)C-iodoantipyrine autoradiography and cryomicrospectrophotometry in alternate slices of the brain tissue. The Ki of (14)C-AIB was markedly increased with hyperosmolar mannitol in both the control (5.8×) and the CGS treated rats (5.2×). With BBB disruption, the O2 consumption was significantly increased (+39%) only in the control but not in the CGS treated rats and was significantly lower (-29%) in the CGS treated than the control rats. The distribution of SvO2 was significantly shifted to the higher concentrations with CGS treatment. Our data demonstrated an increase of O2 consumption by hyperosmolar BBB disruption and attenuation of the increase with NMDA blockade without affecting the degree of BBB disruption.

Background/Aims: Since a thioredoxin-1 (Trx-1) inhibitor, 1-methylpropyl-2-imidazolyl disulfide (PX-12) which is an antitumor agent, significantly decreased vascular permeability in tumor xenografts within a few hours of treatment, we tested whether PX-12 would attenuate blood-brain barrier (BBB) disruption in the early stage of focal cerebral ischemia and whether its action could be affected by vascular endothelial growth factor (VEGF) which interacts with the Trx-1 system. Methods: In rats, 40 min after intravenous infusion of either 25 mg/kg of PX-12 (PX-12 group) or normal saline (control group), a middle cerebral artery (MCA) was occluded. In half of each group, VEGF (10-10 mol/l) was applied topically in the ischemic cortex (IC). Ninety minutes after MCA occlusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid and the volume of 3H-dextran distribution were determined to measure the degree of BBB disruption. VEGF protein levels were determined using Western blot analysis. Results: MCA occlusion increased the Ki in the control (+196%) as well as in the PX-12-treated rats (+90%), but the Ki of the IC of the PX-12 group was lower (-42%) than that of the control rats. VEGF protein levels were decreased in both the IC (-9.5%) and the contralateral cortex (CC; -10.2%) with PX-12 treatment. In the VEGF-treated rats, PX-12 also attenuated (-41%) the Ki of the IC. The difference in the volume of dextran distribution between the IC and the CC became insignificant with PX-12 treatment with or without VEGF application. Conclusion: Our data demonstrated that PX-12 was effective in decreasing BBB disruption in the early stage of focal cerebral ischemia and that VEGF is not an important factor involved in the action of PX-12 on BBB permeability.

One of the important factors altering the degree of blood-brain barrier (BBB) disruption in cerebral ischemia is the anesthetic used. The phosphoinositide 3-kinase (PI3K)/Akt signaling pathway has been reported to be involved in modulating BBB permeability and in isoflurane induced neuroprotection. This study was performed to compare the degree of BBB disruption in focal cerebral ischemia under isoflurane vs pentobarbital anesthesia and to determine whether inhibition of PI3K/Akt would affect the disruption in the early stage of focal cerebral ischemia. Permanent middle cerebral artery (MCA) occlusion was performed in rats under 1.4% isoflurane or pentobarbital (50mg/kg i.p.) anesthesia with controlled ventilation. In half of each group LY294002, which is a PI3K/Akt inhibitor, was applied on the ischemic cortex immediately after MCA occlusion. After one hour of MCA occlusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid (14C-AIB) was determined to quantify the degree of BBB disruption. MCA occlusion increased the Ki both in the isoflurane and pentobarbital anesthetized rats. However, the value of Ki was lower under isoflurane (11.5±6.0μL/g/min) than under pentobarbital (18.3±7.1μL/g/min) anesthesia. The Ki of the contralateral cortex of the pentobarbital group was higher (+74%) than that of the isoflurane group. Application of LY294002 on the ischemic cortex increased the Ki (+99%) only in the isoflurane group. The degree of BBB disruption by MCA occlusion was significantly lower under isoflurane than pentobarbital anesthesia in the early stage of cerebral ischemia. Our data demonstrated the importance of choice of anesthetics and suggest that PI3K/Akt signaling pathway plays a significant role in altering BBB disruption in cerebral ischemia during isoflurane but not during pentobarbital anesthesia.

Even though hypoxic preconditioning has been reported to produce neuroprotection, its effect on blood-brain barrier (BBB) disruption in the early stages of cerebral ischemia within the therapeutic window is not clear. Since hypoxic preconditioning increases expression of vascular endothelial growth factor (VEGF) that modulates vascular permeability, the effects of hypoxic preconditioning and VEGF on BBB permeability were investigated after one hour of focal cerebral ischemia. Rats were exposed to 8% of oxygen for two hours or room air and then 24 hours later, permanent middle cerebral artery (MCA) occlusion was performed. In some of the hypoxic preconditioned rats, a VEGF-A antibody was applied to the ischemic cortex one hour before MCA occlusion. One hour after MCA occlusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid was determined to measure the degree of BBB disruption. MCA occlusion increased the Ki when compared with the contralateral cortex (14.1 ± 4.0 vs 4.2 ± 1.9 μL/g/min, p < 0.0001). Hypoxic preconditioning further increased the Ki in the ischemic cortex when compared with the control rats (25.1 ± 8.7 μL/g/min, p < 0.01). Application of VEGF antibody to the ischemic cortex of the hypoxic preconditioned animals reduced the Ki to the level of the control rats (13.6 ± 5.1 μL/g/min, p < 0.01). Our data demonstrated that hypoxic preconditioning increased BBB disruption through a VEGF related pathway and suggest the possibility of aggravation of brain edema by hypoxic preconditioning in the early stages of cerebral ischemia.

Previous work demonstrated that basal alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor activity did not contribute to the elevated regional cerebral O 2 consumption in the brains of Eker rat (an autism-tuberous sclerosis model). We tested the hypothesis that increased stimulation of AMPA receptors also would not augment cerebral O 2 consumption in the Eker rat. Three cortical sites were prepared for administration of saline, 10 −4 and 10 −3 M AMPA in young (4 weeks) male control Long Evans and Eker rats (70–100 g). Cerebral blood flow ( 14 C-iodoantipyrine) and O 2 consumption (cryomicrospectrophotometry) were determined in isoflurane anesthetized rats. Receptor levels were studied through Western analysis of the GLuR1 subunit of the AMPA receptor. We found significantly increased cortical O 2 consumption (+33%) after 10 −4 M AMPA in control rats. The higher dose of AMPA did not further increase consumption. In the Eker rats, neither dose led to a significant increase in cortical O 2 consumption. Regional blood flow followed a similar pattern to oxygen consumption but cortical O 2 extraction did not differ. Cortical AMPA receptor protein levels were significantly reduced (−21%) in the Eker compared to control rats. Both O 2 consumption and blood flow were significantly elevated in the pons of the Eker rats compared to control. These data demonstrate a reduced importance of AMPA receptors in the control of cortical metabolism, related to reduced AMPA receptor protein, in the Eker rat. This suggests that increasing AMPA receptor activity may not be an effective treatment for children with autism spectrum disorders as they also have reduced AMPA receptor number.

Background and aims Quantitative relationships between soil N availability indices and tree growth are lacking in the oil sands region of Alberta and this can hinder the development of guidelines for the reclamationof the disturbed landscape after oil sands extraction. The aim of this paper was to establish quantitative relationships between soilN availability indices and tree growth in the oil sands region of Alberta. Methods In situ N mineralization rates, in situ N availabilitymeasuredinthefieldusingPlant RootSimulators (PRS™probes),laboratoryaerobicandanaerobicsoilN mineralization rates, and soil C/N and N content were determined for both the forest floor and the 0–20 cm mineral soil in eight jack pine (Pinus banksiana Lamb.) stands in the oil sands region in northern Alberta. Tree growth rates were determined based on changes in tree ring width in the last 6 years and as mean annual aboveground biomass increment. Results Soil N availability indices across those forest stands varied and for each stand it was several times higher in the forest floor than in the mineral soil. The in situ and laboratory aerobic and anaerobic soil N mineralization rates, soil mineralized N, in situ N availability measured using PRS probes, soil C/N ratio and N content in both the forest floor and mineral soil