Hypoxic pulmonary vasoconstriction, carotid body function and erythropoietin production in adult rats perinatally exposed to hyperoxia

Adult mammalians possess three cell systems that are activated by acute bodily hypoxia: pulmonary artery smooth muscle cells (PASMC), carotid body chemoreceptor cells (CBCC) and erythropoietin (EPO)-producing cells. In rats, chronic perinatal hyperoxia causes permanent carotid body (CB) atrophy and functional alterations of surviving CBCC. There are no studies on PASMC or EPO-producing cells. Our aim is to define possible long-lasting functional changes in PASMC or EPO-producing cells (measured as EPO plasma levels) and, further, to analyse CBCC functional alterations. We used 3- to 4-month-old rats born and reared in a normal atmosphere or exposed to perinatal hyperoxia (55–60% O2 for the last 5–6 days of pregnancy and 4 weeks after birth). Perinatal hyperoxia causes an almost complete loss of hypoxic pulmonary vasoconstriction (HPV), which was correlated with lung oxidative status in early postnatal life and prevented by antioxidant supplementation in the diet. O2-sensitivity of K+ currents in the PASMC of hyperoxic animals is normal, indicating that their inhibition is not sufficient to trigger HPV. Perinatal hyperoxia also abrogated responses elicited by hypoxia on catecholamine and cAMP metabolism in the CB. An increase in EPO plasma levels elicited by hypoxia was identical in hyperoxic and control animals, implying a normal functioning of EPO-producing cells. The loss of HPV observed in adult rats and caused by perinatal hyperoxia, comparable to oxygen therapy in premature infants, might represent a previously unrecognized complication of such a medical intervention capable of aggravating medical conditions such as regional pneumonias, atelectases or general anaesthesia in adult life.This work was supported by Grants BFU2012-37459 from the Ministry of Economy and Competitiveness (Spain) and Grant CIBER CB06/06/0050 from the Institute of Health Carlos III (Spain) to C. G. Also supported by Grants SAF2011-28150 to F.P-V and SAF2010-22066-C02-02 to AC from the Ministry of Economy and Competitiveness (Spain).Peer Reviewe

Analysis of Bone Histomorphometry in Rat and Guinea Pig Animal Models Subject to Hypoxia

Hypoxia may be associated with alterations in bone remodeling, but the published results are contradictory. The aim of this study was to characterize the bone morphometry changes subject to hypoxia for a better understanding of the bone response to hypoxia and its possible clinical consequences on the bone metabolism. This study analyzed the bone morphometry parameters by micro-computed tomography (?CT) in rat and guinea pig normobaric hypoxia models. Adult male and female Wistar rats were exposed to chronic hypoxia for 7 and 15 days. Additionally, adult male guinea pigs were exposed to chronic hypoxia for 15 days. The results showed that rats exposed to chronic constant and intermittent hypoxic conditions had a worse trabecular and cortical bone health than control rats (under a normoxic condition). Rats under chronic constant hypoxia were associated with a more deteriorated cortical tibia thickness, trabecular femur and tibia bone volume over the total volume (BV/TV), tibia trabecular number (Tb.N), and trabecular femur and tibia bone mineral density (BMD). In the case of chronic intermittent hypoxia, rats subjected to intermittent hypoxia had a lower cortical femur tissue mineral density (TMD), lower trabecular tibia BV/TV, and lower trabecular thickness (Tb.Th) of the tibia and lower tibia Tb.N. The results also showed that obese rats under a hypoxic condition had worse values for the femur and tibia BV/TV, tibia trabecular separation (Tb.Sp), femur and tibia Tb.N, and BMD for the femur and tibia than normoweight rats under a hypoxic condition. In conclusion, hypoxia and obesity may modify bone remodeling, and thus bone microarchitecture, and they might lead to reductions in the bone strength and therefore increase the risk of fragility fracture.Funding: The present study was supported by grant reference BFU2015-70616-R from MINECOFEDER (Spain Government) and Programa Estratégico IBGM, Escalera de Excelencia, Ref. CCVC8485, Consejería de Educacion, JCyL (Spain)

Análisis de la morfometría ósea en ratas sometidas a diferentes situaciones de hipoxia

El hueso es uno de los tejidos metabólicamente más activos, metabolismo que requiere de un aporte suficiente de oxígeno. En este sentido, se han publicado resultados contradictorios de cómo la hipoxia podría modificar el remodelado óseo y con ello la estructura del hueso. El objetivo del estudio fue valorar el efecto de la hipoxia sobre la morfometría ósea y la densidad mineral ósea medidas por tomografía axil computarizada de alta resolución (HR-pQTc ). Se analizaron 61 ratas wistar a las que se les sometió a diferentes condiciones experimentales: ratas control (sometidas a condiciones de normoxia), ratas sometidas a hipoxia crónica constante y ratas sometidas a hipoxia crónica intermitente. Los animales se sacrificaron por una sobredosis cardiaca de fenobarbital. A continuación, se procedió a la extracción de los huesos, fémur y tibia. Posteriormente se fijaron en etanol al 70% para su posterior análisis. Se utilizó un micro-TAC modelo escáner SKYSCAN 1172 de la marca BRUKER y un software de captación de datos skyscan1172 µCT. La reconstrucción de las imágenes se realizó mediante un software Nrecon utilizándose posterio mente el software de análisis de imagen "CTAN". Se utilizó el SPSS v22 para el análisis estadístico. Nuestros resultados mostraron que las ratas sometidas a condiciones de hipoxia tenían una menor densidad mineral de tejido (TMD) en fémur cortical y un menor grosor trabecular de la tibia. Por otra parte, analizando las ratas sometidas a hipoxia crónica permanente en referencia a las ratas control, se observó que la hipoxia se asoció con un menor espesor cortical de la tibia, menor densidad mineral ósea (BMD) en fémur trabecular y con menor volumen óseo porcentual (BV/TV) del fémur trabecular. Diferenciando por sexos, las ratas hembras sometidas a hipoxia crónica permanente presentaron un menor espesor de la tibia cortical, menor grosor de las trabéculas de la tibia y el fémur y menores valores de BMD en las trabéculas de la tibia y el fémur. Las ratas macho sometidas a hipoxia crónica permanente, tenían un menor número de trabéculas en la tibia. También se observó como las ratas sometidas a hipoxia permanente intermitente, tenían un menor TMD que las ratas control. Nuestros resultados mostraron que en diferentes condiciones de hipoxia se observó un deterioro de la morfometría ósea, probablemente debido a que se produce una alteración del remodelado óseo promovido por la hipoxia tisular

Centralised and Distributed Optimization for Aggregated Flexibility Services Provision

The recent deployment of distributed battery units in prosumer premises offer new opportunities for providing aggregated flexibility services to both distribution system operators and balance responsible parties. The optimization problem presented in this paper is formulated with an objective of cost minimization which includes energy and battery degradation cost to provide flexibility services. A decomposed solution approach with the alternating direction method of multipliers (ADMM) is used instead of commonly adopted centralised optimization to reduce the computational burden and time, and then reduce scalability limitations. In this work we apply a modified version of ADMM that includes two new features with respect to the original algorithm: first, the primal variables are updated concurrently, which reduces significantly the computational cost when we have a large number of involved prosumers; second, it includes a regularization term named Proximal Jacobian (PJ) that ensures the stability of the solution. A case study is presented for optimal battery operation of 100 prosumer sites with real-life data. The proposed method finds a solution which is equivalent to the centralised optimization problem and is computed between 5 and 12 times faster. Thus, aggregators or large-scale energy communities can use this scalable algorithm to provide flexibility services.Comment: 10 pages, 7 figure

The response of plant community diversity to alien invasion: evidence from a sand dune time series

This study examines the process of invasion of coastal dunes in north-eastern Italy along a 60-year time series considering alien attributes (origin, residence time, invasive status, and growth form strategy) and habitat properties (species richness, diversity and evenness, proportion of aliens, and proportion of focal species). Vegetation changes through time were investigated in four sandy coastal habitats, using a fine-scale diachronic approach that compared vegetation data collected by use of the same procedure, in four time periods, from the 1950s to 2011. Our analysis revealed an overall significant decline of species richness over the last six decades. Further, both the average number of species per plot and the mean focal species proportion were proved to be negatively affected by the increasing proportion of alien species at plot level. The severity of the impact, however, was found to be determined by a combination of species attributes, habitat properties, and human disturbance suggesting that alien species should be referred to as ‘‘passengers’’ and not as ‘‘drivers’’ of ecosystem change. Passenger alien species are those which take advantage of disturbances or other changes to which they are adapted but that lead to a decline in native biodiversity. Their spread is facilitated by widespread anthropogenic environmental alterations, which create new, suitable habitats, and ensure human-assisted dispersal, reducing the distinctiveness of plant communities and inducing a process of biotic homogenization

Effect of alirocumab on mortality after acute coronary syndromes. An analysis of the ODYSSEY OUTCOMES randomized clinical trial

Background: Previous trials of PCSK9 (proprotein convertase subtilisin-kexin type 9) inhibitors demonstrated reductions in major adverse cardiovascular events, but not death. We assessed the effects of alirocumab on death after index acute coronary syndrome. Methods: ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) was a double-blind, randomized comparison of alirocumab or placebo in 18 924 patients who had an ACS 1 to 12 months previously and elevated atherogenic lipoproteins despite intensive statin therapy. Alirocumab dose was blindly titrated to target achieved low-density lipoprotein cholesterol (LDL-C) between 25 and 50 mg/dL. We examined the effects of treatment on all-cause death and its components, cardiovascular and noncardiovascular death, with log-rank testing. Joint semiparametric models tested associations between nonfatal cardiovascular events and cardiovascular or noncardiovascular death. Results: Median follow-up was 2.8 years. Death occurred in 334 (3.5%) and 392 (4.1%) patients, respectively, in the alirocumab and placebo groups (hazard ratio [HR], 0.85; 95% CI, 0.73 to 0.98; P=0.03, nominal P value). This resulted from nonsignificantly fewer cardiovascular (240 [2.5%] vs 271 [2.9%]; HR, 0.88; 95% CI, 0.74 to 1.05; P=0.15) and noncardiovascular (94 [1.0%] vs 121 [1.3%]; HR, 0.77; 95% CI, 0.59 to 1.01; P=0.06) deaths with alirocumab. In a prespecified analysis of 8242 patients eligible for ≥3 years follow-up, alirocumab reduced death (HR, 0.78; 95% CI, 0.65 to 0.94; P=0.01). Patients with nonfatal cardiovascular events were at increased risk for cardiovascular and noncardiovascular deaths (P<0.0001 for the associations). Alirocumab reduced total nonfatal cardiovascular events (P<0.001) and thereby may have attenuated the number of cardiovascular and noncardiovascular deaths. A post hoc analysis found that, compared to patients with lower LDL-C, patients with baseline LDL-C ≥100 mg/dL (2.59 mmol/L) had a greater absolute risk of death and a larger mortality benefit from alirocumab (HR, 0.71; 95% CI, 0.56 to 0.90; Pinteraction=0.007). In the alirocumab group, all-cause death declined wit h achieved LDL-C at 4 months of treatment, to a level of approximately 30 mg/dL (adjusted P=0.017 for linear trend). Conclusions: Alirocumab added to intensive statin therapy has the potential to reduce death after acute coronary syndrome, particularly if treatment is maintained for ≥3 years, if baseline LDL-C is ≥100 mg/dL, or if achieved LDL-C is low. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01663402

Chemoreceptor activity is normal in mice lacking the NK1 receptor

Substance P has been proposed to be an important neurotransmitter in the carotid body with the neurokinin 1 (NK1) receptor, mediating excitation between the glomus cells and afferent nerve endings. In order to better understand the role of substance P, this study examined chemoreceptor afferent activity, in vitro, and tissue catecholamine levels and release in adult, wild-type mice and mice lacking the gene for the NK1 receptor (NK1-KO). Groups did not differ significantly in body weight, carotid body dopamine content or carotid body norepinephrine content. In wild-type mice, single unit activity increased from 0.59 ± 0.14 Hz to 19.78 ± 2.27 Hz during superfusion with strong hypoxia (PO2 ≈ 25 Torr). Chemoreceptor activity in NK1-KO mice, increased from 0.71 ± 0.23 to 21.50 ± 3.62 Hz, and neither baseline or peak frequencies were significantly different from the wild-type group. Less severe hypoxia (PO2 ≈ 45 torr), evoked peak activities of 12.50 ± 1.88 and 10.64 ± 3.72 Hz in wild-type and NK1-KO mice, which were also not significantly different. In response to severe hypoxia, free-tissue catecholamine increased to 4.92 ± 0.85 μM in wild-type mice and 4.26 ± 0.63 μM in NK1-KO mice, which were also not significantly different. It may therefore be concluded that loss of NK1 receptors has little effect on chemoreceptor function in the mouse, and thus they play, at best, a minor role in the hypoxic chemoreception process.Financial support from Fondo de Investigaciones Sanitarias (01/0728) and Junta de Castilla y León (VA46/00B) to R. Rigual and from DGICYT (BFI2001-1713) to C. Gonzalez is gratefully acknowledged.Peer Reviewe

Hypoxia transduction by carotid body chemoreceptors in mice lacking dopamine D2 receptors

Hypoxia-induced dopamine (DA) release from carotid body (CB) glomus cells and activation of postsynaptic D2 receptors have been proposed to play an important role in the neurotransmission process between the glomus cells and afferent nerve endings. To better resolve the role of D2 receptors, we examined afferent nerve activity, catecholamine content and release, and ventilation of genetically engineered mice lacking D2 receptors (D2 -/- mice). Single-unit afferent nerve activities of D2 -/- mice in vitro were significantly reduced by 45% and 25% compared with wild-type (WT) mice during superfusion with saline equilibrated with mild hypoxia (PO2 ∼50 Torr) or severe hypoxia (PO2 ∼20 Torr), respectively. Catecholamine release in D2 -/- mice was enhanced by 125% in mild hypoxia and 75% in severe hypoxia compared with WT mice, and the rate of rise was increased in D2 -/- mice. We conclude that CB transduction of hypoxia is still present in D2 -/- mice, but the response magnitude is reduced. However, the ventilatory response to acute hypoxia is maintained, perhaps because of an enhanced processing of chemoreceptor input by brain stem respiratory nuclei. Copyright © 2007 the American Physiological Society.This work was supported by Spanish Dirección General de Investigación Científico Técnica (DGICYT) Grant BFI 2003-1627 and SAF 2006-00416 (to R. J. Rigual), National Heart, Lung, and Blood Institute Grant HL-073500 (to D. F. Donnelly), and Spanish DGICYT Grants BFU 2004-06394, FIS PI042462, CIBER CB06/06/0050, and JCyL VA011C05 (to C. González).Peer Reviewe

Acetoaminophen potentiates staurosporine-induced death in a human neuroblastoma cell line

Background and purpose: Neuroblastoma is the most common solid tumour in infants characterized by a high resistance to apoptosis. Recently, the cyclo-oxygenase pathway has been considered a potential target in the treatment of different kinds of tumours. The aim of the present work was to investigate a possible relationship between cyclo-oxygenase pathway and stauroporine-induced apoptosis in the neuroblastoma cell line SH-SY5Y. Experimental approach: Cellular viability was measured by release of LDH. DNA fragmentation was visualized by electrophoresis on agarose gel containing ethidium bromide. Cyclo-oxygenase activity was measured in microsomal fractions obtained from cells by quantification of its final product PGE(2) by RIA. Caspase-3 activity was measured fluorimetrically and Western blot analysis was performed to assess cytochrome c expression. Key results: We have found that staurosporine (500 nM) induced cellular death in a time-dependent manner in SH-SY5Y human neuroblastoma cells. Cyclo-oxygenase enzymatic activity was present in SH-SY5Y human neuroblastoma cells under basal conditions and pharmacological experiments using COX inhibitors indicate that cyclo-oxygenase-1 and cyclo-oxygenase-3 are the active isoforms in these cells. Co-incubation of SH-SY5Y cells with staurosporine (500 nM) and acetaminophen for 24 h potentiated staurosporine-mediated cellular death in a concentration-dependent manner. This process is mediated by an increase in cytochrome c release and caspase 3 activation and is prevented by N-acetylcysteine or the superoxide dismutase mimetic, MnTBAP. Conclusions and implications: Acetaminophen potentiates staurosporine-mediated neuroblastoma cell death. The mechanism of action of acetaminophen seems to be related to production of reactive oxygen species and decreased intracellular glutathione levels

Hypoxic pulmonary vasoconstriction in the absence of pretone:essential role forintracellular Ca2+ release

Hypoxic pulmonary vasoconstriction (HPV) maintains blood oxygenation during acute hypoxia but contributes to pulmonary hypertension during chronic hypoxia. The mechanisms of HPV remain controversial, in part because HPV is usually studied in the presence of agonist-induced preconstriction (‘pretone’). This potentiates HPV but may obscure and distort its underlying mechanisms. We therefore carried out an extensive assessment of proposed mechanisms contributing to HPV in isolated intrapulmonary arteries (IPAs) in the absence of pretone by using a conventional small vessel myograph. Hypoxia elicited a biphasic constriction consisting of a small transient (phase 1) superimposed upon a sustained (phase 2) component. Neither phase was affected by the L-type Ca(2+) channel antagonists diltiazem (10 and 30 μm) or nifedipine (3 μm). Application of the store-operated Ca(2+) entry (SOCE) blockers BTP2 (10 μm) or SKF96365 (50 μm) attenuated phase 2 but not phase 1, whereas a lengthy (30 min) incubation in Ca(2+)-free physiological saline solution similarly reduced phase 2 but abolished phase 1. No further effect of inhibition of HPV was observed if the sarco/endoplasmic reticulum Ca(2+)-ATPase inhibitor cyclopiazonic acid (30 μm) was also applied during the 30 min incubation in Ca(2+)-free physiological saline solution. Pretreatment with 10 μm ryanodine and 15 mm caffeine abolished both phases, whereas treatment with 100 μm ryanodine attenuated both phases. The two-pore channel blocker NED-19 (1 μm) and the nicotinic acid adenine dinucleotide phosphate (NAADP) antagonist BZ194 (200 μm) had no effect on either phase of HPV. The lysosomal Ca(2+)-depleting agent concanamycin (1 μm) enhanced HPV if applied during hypoxia, but had no effect on HPV during a subsequent hypoxic challenge. The cyclic ADP ribose antagonist 8-bromo-cyclic ADP ribose (30 μm) had no effect on either phase of HPV. Neither the Ca(2+)-sensing receptor (CaSR) blocker NPS2390 (0.1 and 10 μm) nor FK506 (10 μm), a drug which displaces FKBP12.6 from ryanodine receptor 2 (RyR2), had any effect on HPV. HPV was virtually abolished by the rho kinase blocker Y-27632 (1 μm) and attenuated by the protein kinase C inhibitor Gö6983 (3 μm). Hypoxia for 45 min caused a significant increase in the ratio of oxidised to reduced glutathione (GSSG/GSH). HPV was unaffected by the NADPH oxidase inhibitor VAS2870 (10 μm), whereas phase 2 was inhibited but phase 1 was unaffected by the antioxidants ebselen (100 μm) and TEMPOL (3 mm). We conclude that both phases of HPV in this model are mainly dependent on [Ca(2+)](i) release from the sarcoplasmic reticulum. Neither phase of HPV requires voltage-gated Ca(2+) entry, but SOCE contributes to phase 2. We can detect no requirement for cyclic ADP ribose, NAADP-dependent lysosomal Ca(2+) release, activation of the CaSR, or displacement of FKBP12.6 from RyR2 for either phase of HPV. Sustained HPV is associated with an oxidising shift in the GSSG/GSH redox potential and is inhibited by the antioxidants ebselen and TEMPOL, consistent with the concept that it requires an oxidising shift in the cell redox state or the generation of reactive oxygen species