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Chronic sublethal hypoxia

Daoud Dounia, Battison Andrea, Natalie Lefort, Jordana Lynne Van Geest
In Atlantic Canada and other salmon-growing regions, treatment of sea lice infestations in salmon aquaculture is necessary to protect fish health. The product Salmosan®, which contains the organophosphate azamethiphos as the active ingredient, is a pesticide presently used for treatment against sea lice. It is applied as a bath treatment and then released into the surrounding seawater. The potential for lethality to non-target species following acute and chronic exposures to Salmosan® has been studied over the past decade, however, the potential for sublethal effects on lobsters remains a concern...
September 1, 2016: Ecotoxicology and Environmental Safety
Qi Li, Masayuki Tsuneki, Michael Krauthammer, Rachael Couture, Michael Schwartz, Joseph A Madri
Premature infants are at an increased risk of developing cognitive and motor handicaps due to chronic hypoxia. Although the current therapies have reduced the incidence of these handicaps, untoward side effects abound. Using a murine model of sublethal hypoxia, we demonstrated reduction in several transcription factors that modulate expression of genes known to be involved in several neural functions. We demonstrate the induction of these genes by minocycline, a tetracycline antibiotic with noncanonical functions, in both in vitro and in vivo studies...
September 2015: American Journal of Pathology
C M Couillard, L E Burridge
In the Bay of Fundy, New Brunswick, sea lice outbreaks in caged salmon are treated with pesticides including Salmosan(®), applied as bath treatments and then released into the surrounding seawater. The effect of chronic exposure to low concentrations of this pesticide on neighboring lobster populations is a concern. Adult male lobsters were exposed to 61 ngL(-1) of azamethiphos (a.i. in Salmosan(®) formulation) continuously for 10 days. In addition to the direct effects of pesticide exposure, effects on the ability to cope with shipping conditions and the persistence of the effects after a 24h depuration period in clean seawater were assessed...
May 2015: Ecotoxicology and Environmental Safety
Ying Zhu, Christopher C Wendler, Olivia Shi, Scott A Rivkees
Periventricular white matter injury (PWMI) is the most common cause of brain injury in preterm infants. It is believed that loss of late oligodendrocyte progenitor cells (OPCs) and disrupted maturation of oligodendrocytes contributes to defective myelination in PWMI. At present, no clinically approved drugs are available for treating PWMI. Previously, we found that diazoxide promotes myelination and attenuates brain injury in the chronic sublethal hypoxia model of PWMI. In this study, we investigated the mechanisms by which diazoxide promotes myelination...
October 24, 2014: Brain Research
R N Garcia, K W Chung, P B Key, L E Burnett, L D Coen, M E Delorenzo
Mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. Few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased CO2 (low pH), are less understood. Toxicity was assessed at 4 and 21 days for larval and juvenile stages of the Eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, using two pyrethroids (resmethrin and permethrin), an organophosphate (naled), and a juvenile growth hormone mimic (methoprene)...
April 2014: Archives of Environmental Contamination and Toxicology
Diana Amaral Monteiro, Juliana Montovani Thomaz, Francisco Tadeu Rantin, Ana Lúcia Kalinin
The growing Hg input in aquatic environments results in high accumulation of mercury in fish tissue and their consumers, which poses a serious risk to humans and ecosystems. The aim of this study was to evaluate the effects of the inorganic mercury exposure on cardiorespiratory responses in two species of neotropical fish ecologically distinct, matrinxã (Brycon amazonicus) and traíra (Hoplias malabaricus). Matrinxãs were exposed to a nominal and sublethal concentration of 0.15 mgL(-1) of HgCl2 for 96 h. Traíras were exposed to trophic doses (each 4 days, during 30 days) of inorganic Hg (0...
September 15, 2013: Aquatic Toxicology
David P Basile, Melissa D Anderson, Timothy A Sutton
Acute kidney injury (AKI) is the leading cause of nephrology consultation and is associated with high mortality rates. The primary causes of AKI include ischemia, hypoxia, or nephrotoxicity. An underlying feature is a rapid decline in glomerular filtration rate (GFR) usually associated with decreases in renal blood flow. Inflammation represents an important additional component of AKI leading to the extension phase of injury, which may be associated with insensitivity to vasodilator therapy. It is suggested that targeting the extension phase represents an area potential of treatment with the greatest possible impact...
April 2012: Comprehensive Physiology
Hong Wa Yung, Mathew Cox, Martha Tissot van Patot, Graham J Burton
Pregnancy at high altitude is associated with a reduction in birth weight of ∼100 g/1000 m of ascent. The underlying mechanisms are unclear but may involve alteration in energy-demanding activities, such as protein synthesis. To test this hypothesis, both in vivo and in vitro approaches were used. Placental tissues from pregnant women residing at 3100 m were studied, and placental cells were incubated under hypoxia. In the 3100-m placentas, we observed dilation of endoplasmic reticulum (ER) cisternae, increased phosphorylation of eukaryotic initiation factor 2 subunit α (P-eIF2α), reduced AKT phosphorylation, and reduced P-4E-BP1 but increased 4E-BP1 protein compared to sea level controls...
May 2012: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Pei-Jen Chen, Chih-Hsiang Su, Chi-Yen Tseng, Shih-Wei Tan, Chiung-Hsiang Cheng
Iron-based nanotechnologies are increasingly used for environmental remediation; however, toxicologic impacts of iron nanoparticles on the aquatic ecosystem remain poorly understood. We treated larvae of medaka fish (Oryzias latipes) with thoroughly characterized solutions containing carboxymethyl cellulose (CMC)-stabilized nanoscale zerovalent iron (nZVI), aged nanoscale iron oxides (nFe-oxides) or ferrous ion (Fe[II]) for 12-14 days' aqueous exposure to assess the causal toxic effect(s) of iron NPs on the fish...
2011: Marine Pollution Bulletin
Wen-Chun J Lan, Matthew Priestley, Sonia R Mayoral, Lu Tian, Mehrdad Shamloo, Anna A Penn
Male sex is an independent risk factor for long-term neurologic deficits in human preterm infants. Using a chronic, sublethal hypoxia (CSH) mouse model of preterm brain injury, we recently demonstrated acute brain volume loss with an increased male susceptibility to hippocampal volume loss and hypomyelination. We now characterize the long-term, sex-specific effects of CSH on cognition and brain growth. Neonatal mice were treated with CSH for 8 d, raised in normoxia thereafter and underwent behavioral testing at 6 wk of age...
July 2011: Pediatric Research
Birgit Fogal, Carolyn McClaskey, Sha Yan, Henglin Yan, Scott A Rivkees
BACKGROUND: Several clinical conditions are associated with white matter injury, including periventricular white matter injury (PWMI), which is a form of brain injury sustained by preterm infants. It has been suggested that white matter injury in this condition is due to altered oligodendrocyte (OL) development or death, resulting in OL loss and hypomyelination. At present drugs are not available that stimulate OL proliferation and promote myelination. Evidence suggests that depolarizing stimuli reduces OL proliferation and differentiation, whereas agents that hyperpolarize OLs stimulate OL proliferation and differentiation...
2010: PloS One
Sonia R Mayoral, Ghezal Omar, Anna A Penn
Male sex is a well-established risk factor for poor neurodevelopmental outcome after premature birth. The mechanisms behind this sex-related difference are unknown. The damage associated with prematurity can be mimicked in rodents by prolonged exposure to sublethal postnatal hypoxia. This chronic hypoxia leads to anatomical changes in mice that strongly resemble the loss of volume, decreased myelination, and ventriculomegaly seen in preterm newborns. However, no sex differences have been previously noted in this rodent model...
September 2009: Pediatric Research
Halima Chahboune, Laura R Ment, William B Stewart, Douglas L Rothman, Flora M Vaccarino, Fahmeed Hyder, Michael L Schwartz
Preterm birth results in significant neurodevelopmental disability. A neonatal rodent model of chronic sublethal hypoxia (CSH), which mimics effects of preterm birth, was used to characterize neurodevelopmental consequences of prolonged exposure to hypoxia using tissue anisotropy measurements from diffusion tensor imaging. Corpus callosum, cingulum, and fimbria of the hippocampus revealed subtle, yet significant, hypoxia-induced modifications during maturation (P15-P51). Anisotropy differences between control and CSH mice were greatest at older ages (>P40) in these regions...
December 2009: Cerebral Cortex
Ze D Jiang, Dorothea M Brosi, C Chen, Andrew R Wilkinson
OBJECTIVE: To examine neuronal function of the auditory brainstem in neonatal chronic lung disease (CLD) and detect any differences from perinatal asphyxia. METHODS: Infants with CLD and infants after perinatal asphyxia were studied at term (37-42 weeks postconceptional age). Wave amplitudes of maximum length sequence brainstem auditory evoked response (MLS BAER) were recorded and compared between CLD and asphyxia. RESULTS: The amplitudes of waves I, III and V, and V/I and V/III amplitude ratios in CLD infants did not differ from those in normal term controls at all click rates 21-910/s...
May 2009: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
William E Truog, Dong Xu, Ikechukwu I Ekekezie, Sherry Mabry, Mo Rezaiekhaligh, Stan Svojanovsky, Michael J Soares
It is unclear how sublethal hypoxia affects lung development. To investigate the effects of chronic hypoxia on postnatal lung remodeling, we treated neonatal rats with FIO2 of 0.12 for 10 d and analyzed lung development by morphometry and gene expression by DNA microarray. Our results showed the neonatal rats exposed to hypoxia reduced body weight by 42% and wet lung weight by 32% compared with the neonatal rats exposed to normoxia. In the neonatal rats exposed to hypoxia, the radial alveolar counts were decreased to 5...
July 2008: Pediatric Research
K Yao, J A Gietema, S Shida, M Selvakumaran, X Fonrose, N B Haas, J Testa, P J O'Dwyer
Hypoxia is an important selective force in the clonal evolution of tumours. Through HIF-1 and other transcription factors combined with tumour-specific genetic alterations, hypoxia is a dominant factor in the angiogenic phenotype. Cellular adaptation to hypoxia is an important requirement of tumour progression independent of angiogenesis. The adaptive changes, insofar as they alter hypoxia-induced apoptosis, are likely to determine responsiveness to antiangiogenic strategies. To investigate this adaptation of tumour cells to hypoxia, we recreated in vitro the in vivo situation of chronic intermittent exposure to low-oxygen levels...
December 12, 2005: British Journal of Cancer
K Liber, L Weber, C Lévesque
Lake trout fry (Salvelinus namaycush) were exposed in laboratory experiments to two wastewater treatment polymers, one anionic (MagnaFloc 156) and one cationic (MagnaFloc 368; Ciba Speciality Chemical), to determine if these chemicals which are used and discharged by mining operations in Canada's North pose a significant hazard to juvenile fishes. The cationic polymer was substantially more toxic to lake trout fry than the anionic polymer, with 96-h LC50 estimates of 2.08 and >600 mg/l, respectively. Separate 30-d exposure experiments yielded no observed and lowest observed effect concentrations, respectively, of 0...
December 2005: Chemosphere
Michael L Schwartz, Flora Vaccarino, Monica Chacon, Wei Li Yan, Laura R Ment, William B Stewart
Preterm birth results in significant neurodevelopmental disability. The neonatal rodent model of chronic sublethal hypoxia faithfully mimics the effect of preterm birth on the developing brain. We employed this model to test the hypothesis that the hypoxia that accompanies preterm birth results in inappropriate signaling of apoptotic mechanisms in developing brain. We performed cortical cell counts, determinations of neuronal size and Western analyses of the apoptosis related proteins, Bcl-2 and Bax, in rat pups who were raised in chronic hypoxia (FiO2 9...
December 2004: Seminars in Perinatology
Jared Weiss, Bayan Takizawa, Aaron McGee, William B Stewart, Heping Zhang, Laura Ment, Michael Schwartz, Stephen Strittmatter
Premature human infants frequently suffer from periventricular leukomalacia (PVL) characterized by the loss of central myelinated tracts in the brain [Neuropathology, 22 (2002) 193]. Rodent chronic sublethal hypoxia (CSH) from P3 to 33 (postnatal day 3-33) provides a model for PVL characterized by cerebral ventriculomegaly and reductions in cerebral white matter volume [Brain Res. Dev. Brain Res. 111 (1998) 197; Proc. Natl. Acad. Sci. USA 100 (2003) 11718]. Here, we demonstrate that mice exposed to CSH from P3 to P33 followed by normoxia from P33 to P75 continue to exhibit a locomotor hyperactivity that resembles behavioral changes observed in some human children with very low birth weights...
September 2004: Experimental Neurology
Sheila M Curristin, Anjun Cao, William B Stewart, Heping Zhang, Joseph A Madri, Jon S Morrow, Laura R Ment
Infants born prematurely risk significant life-long cognitive disability, representing a major pediatric health crisis. The neuropathology of this cohort is accurately modeled in mice subjected to sublethal postnatal hypoxia. Massively parallel transcriptome analysis using cDNA microchips (9,262 genes), combined with immunohistochemical and protein assays, reveals that sublethal hypoxia accentuates genes subserving presynaptic function, and it suppresses genes involved with synaptic maturation, postsynaptic function, and neurotransmission...
November 26, 2002: Proceedings of the National Academy of Sciences of the United States of America
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