Effect of Hyperbaric oxygen on myelin injury and repair after hypoxic-ischemic brain damage in adult rat.

INTRODUCTION: Hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of death and neurological disability with limited options for treatment in neonates, children and adults worldwide. The pathogenesis and treatment of white matter (WM) injury in adult patients with HIE remains largely elusive. METHODS: Sixty male Sprague-Dawley rats were randomly divided into control group, sham-operated group (HBO treatment 6 days after sham operation), and Hypoxia-ischemia (HI) induced brain damage group (receiving left carotid arteries ligation + hypoxia treatment), 1.5ATA hyperbaric oxygen group (HI + 1.5ATA HBOT) and 2.5ATA HBOT group (HI + 2.5ATA HBOT). All the rats were evaluated by water maze before operation, and 6 days after operation, and the function of learning and memory was evaluated; Demyelination in the hippocampus and prefrontal cortex was observed by Luxol fast blue staining (LFB) and MBP immunostaining; the number of Myelin Oligodendrocyte Glycoprotein (MOG),glial fibrillary acidic protein (GFAP), ionic calcium-binding adaptor (Iba-1) and NG2 positive cells in the hippocampus and prefrontal cortex were determined by immunofluorescence staining. The expression of interleukin-1ß (IL-1ß), IL-6 and tumor necrosis factor (TNF-α), Hypoxia Inducible Factor 1 Subunit Alpha (HIF1-α) and Superoxide dismutase (SOD) in brain and serum of rats were measured by Western Blot method and Enzyme linked immunosorbent assay (ELISA). RESULTS: Compared with those in the normal control group and sham-operated group, in the HI group, the learning and memory abilities of rats were significantly decreased (P < 0.05), the intensity of LFB and MBP immunostaining in hippocampus and prefrontal cortex was significantly decreased (P < 0.05); the number of MOG positive oligodendrocytes (OLs) significantly decreased (P < 0.05), whereas the number of Iba-1, GFAP, NG2 positive microglias, astrocytes and oligodendrocyte precursors (OPCs) was increased (P < 0.05); the level of IL-1ß, IL-6, TNF-α and HIF-1a in brain and serum were significantly increased (P < 0.05), whereas SOD was significantly decreased in brain and increased in serum. Compared with those in the HI group, in both 1.5ATA and 2.5ATA HBOT group, the learning and memory abilities were significantly increased (P < 0.05); the intensity of LFB and MBP immunostaining in the hippocampus and prefrontal cortex was significantly increased (P < 0.05); the number of MOG positive OLs significantly increased (P < 0.05); the number of Iba-1, GFAP, NG2 positive microglias, astrocytes and OPCs was decreased (P < 0.05); the level of IL-1ß, IL-6, TNF-α and HIF-1a in brain and serum were significantly decreased (P < 0.05); the level of SOD was significantly increased in brain and decreased in serum. Morever, compared with those in the 1.5ATA group, 2.5ATA provided better treatment results (P < 0.05). CONCLUSION: In the present study, we demonstrated the mechanism of different pressure HBOT on HI induced brain injury from three levels: (1) On a tissue level, HBOT protects against HI induced myelin injury; (2) On a cellular level, HBOT attenuates HI-induced OL loss, suppresss the reactive activation of astrocyte and microglia, and may promote OPC to differentiate into OL; (3) On a molecular level, HBOT inhibites neuroinflammation, and balances oxidative damage and antioxidant capacity. Among the above effects, 2.5ATA HBOT is better than 1.5ATA HBOT. Ongoing research will continue to seek out the signalling pathways and molecules mechanisms on different pressure of HBOT-related myelin protection, and possibly expand suitable HBOT use in adult HIE clinically.

[Shenfu Injection alleviates sepsis-associated lung injury by regulating HIF-1α].

Shenfu Injection(SFI) is praised for the high efficacy in the treatment of septic shock. However, the precise role of SFI in the treatment of sepsis-associated lung injury is not fully understood. This study investigated the protective effect of SFI on sepsis-associated lung injury by a clinical trial and an animal experiment focusing on the hypoxia-inducing factor-1α(HIF-1α)-mediated mitochondrial autophagy. For the clinical trial, 70 patients with sepsis-associated lung injury treated in the emergency intensive care unit of the First Affiliated Hospital of Zhengzhou University were included. The levels of interleukin(IL)-6 and tumor necrosis factor(TNF)-α were measured on days 1 and 5 for every patient. Real-time quantitative polymerase chain reaction(RT-qPCR) was performed to determine the mRNA level of hypoxia inducible factor-1α(HIF-1α) in the peripheral blood mononuclear cells(PBMCs). For the animal experiment, 32 SPF-grade male C57BL/6J mice(5-6 weeks old) were randomized into 4 groups: sham group(n=6), SFI+sham group(n=10), SFI+cecal ligation and puncture(CLP) group(n=10), and CLP group(n=6). The body weight, body temperature, wet/dry weight(W/D) ratio of the lung tissue, and the pathological injury score of the lung tissue were recorded for each mouse. RT-qPCR and Western blot were conducted to determine the expression of HIF-1α, mitochondrial DNA(mt-DNA), and autophagy-related proteins in the lung tissue. The results of the clinical trial revealed that the SFI group had lowered levels of inflammatory markers in the blood and alveolar lavage fluid and elevated level of HIF-1α in the PBMCs. The mice in the SFI group showed recovered body temperature and body weight. lowered TNF-α level in the serum, and decreased W/D ratio of the lung tissue. SFI reduced the inflammatory exudation and improved the alveolar integrity in the lung tissue. Moreover, SFI down-regulated the mtDNA expression and up-regulated the protein levels of mitochondrial transcription factor A(mt-TFA), cytochrome c oxidase Ⅳ(COXⅣ), HIF-1α, and autophagy-related proteins in the lung tissue of the model mice. The findings confirmed that SFI could promote mitophagy to improve mitochondrial function by regulating the expression of HIF-1α.

A critical review of Astragalus polysaccharides: From therapeutic mechanisms to pharmaceutics.

As the important active ingredients of Astragali Radix (AR), Astragalus polysaccharides (APs) have therapeutic potential for multiple diseases including nervous system diseases, cardiovascular diseases, diabetes mellitus, and cancer. A large number of cell experiments combined with animal experiments have shed light on the therapeutic mechanisms and therapeutic effects of APs on a variety of diseases. However, the clinical application of APs is not widespread, except for the use of injected APs in the clinical adjuvant therapy of cancer. Due to the excessive molecular weight, bulky, low solubility and negatively charged characteristics, APs have low bioavailability which limits their clinical application. With the deepening of researches on the pharmaceutics of APs, the nanocrystals and moderate structural modification enormously boost the bioavailability, which may expand the application of APs. This review summarizes the studies in pharmacodynamic properties and pharmaceutics of APs, with the purpose of providing experimental researches and clinical application data for expanding the clinical development through expounding the therapeutic mechanisms and pharmaceutical researches of APs.

Iodinated cyanine dye-based nanosystem for synergistic phototherapy and hypoxia-activated bioreductive therapy.

Photodynamic therapy (PDT) has been applied in cancer treatment by utilizing reactive oxygen species (ROS) to kill cancer cells. However, the effectiveness of PDT is greatly reduced due to local hypoxia. Hypoxic activated chemotherapy combined with PDT is expected to be a novel strategy to enhance anti-cancer therapy. Herein, a novel liposome (LCT) incorporated with photosensitizer (PS) and bioreductive prodrugs was developed for PDT-activated chemotherapy. In the design, CyI, an iodinated cyanine dye, which could simultaneously generate enhanced ROS and heat than other commonly used cyanine dyes, was loaded into the lipid bilayer; while tirapazamine (TPZ), a hypoxia-activated prodrug was encapsulated in the hydrophilic nucleus. Upon appropriate near-infrared (NIR) irradiation, CyI could simultaneously produce ROS and heat for synergistic PDT and photothermal therapy (PTT), as well as provide fluorescence signals for precise real-time imaging. Meanwhile, the continuous consumption of oxygen would result in a hypoxia microenvironment, further activating TPZ free radicals for chemotherapy, which could induce DNA double-strand breakage and chromosome aberration. Moreover, the prepared LCT could stimulate acute immune response through PDT activation, leading to synergistic PDT/PTT/chemo/immunotherapy to kill cancer cells and reduce tumor metastasis. Both in vitro and in vivo results demonstrated improved anticancer efficacy of LCT compared with traditional PDT or chemotherapy. It is expected that these iodinated cyanine dyes-based liposomes will provide a powerful and versatile theranostic strategy for tumor target phototherapy and PDT-induced chemotherapy.

Hypoxia, Metabolic Reprogramming, and Drug Resistance in Liver Cancer.

Hypoxia, low oxygen (O2) level, is a hallmark of solid cancers, especially hepatocellular carcinoma (HCC), one of the most common and fatal cancers worldwide. Hypoxia contributes to drug resistance in cancer through various molecular mechanisms. In this review, we particularly focus on the roles of hypoxia-inducible factor (HIF)-mediated metabolic reprogramming in drug resistance in HCC. Combination therapies targeting hypoxia-induced metabolic enzymes to overcome drug resistance will also be summarized. Acquisition of drug resistance is the major cause of unsatisfactory clinical outcomes of existing HCC treatments. Extra efforts to identify novel mechanisms to combat refractory hypoxic HCC are warranted for the development of more effective treatment regimens for HCC patients.

Establishing a high throughput drug screening system for cerebral ischemia using zebrafish larvae.

We previously generated an ischemic stroke in a zebrafish model using N2 gas perfusion; however, this model was an unsuitable drug screening system due to low throughput. In this study, we examined a zebrafish ischemic stroke model using an oxygen absorber to assess drug effects. Hypoxic exposure more than 2 h using the oxygen absorber significantly induced cell death in the brain and damage to the neuronal cells. To confirm the utility of the ischemic model induced by the oxygen absorber, we treated zebrafish with neuroprotective agents. MK-801, an N-methyl-d-aspartate (NMDA) receptor antagonist, significantly suppressed cell death in the brain, and edaravone, a free radical scavenger, significantly reduced the number of dead cells. These results suggest that the activation of NMDA receptors and the production of reactive oxygen species induce neuronal cell damage in accordance with previous mammalian reports. We demonstrate the suitability of an ischemic stroke model in zebrafish larvae using the oxygen absorber, enabling a high throughput drug screening.

Comparison of coenzyme Q10 or fish oil for prevention of intermittent hypoxia-induced oxidative injury in neonatal rat lungs.

BACKGROUND: Neonatal intermittent hypoxia (IH) results in oxidative distress in preterm infants with immature antioxidant systems, contributing to lung injury. Coenzyme Q10 (CoQ10) and fish oil protect against oxidative injury. We tested the hypothesis that CoQ10 is more effective than fish oil for prevention of IH-induced lung injury in neonatal rats. METHODS: Newborn rats were exposed to two clinically relevant IH paradigms at birth (P0): (1) 50% O2 with brief hypoxia (12% O2); or (2) room air (RA) with brief hypoxia (12% O2), until P14 during which they were supplemented with daily oral CoQ10, fish oil, or olive oil from P0 to P14. Pups were studied at P14 or placed in RA until P21 with no further treatment. Lungs were assessed for histopathology and morphometry; biomarkers of oxidative stress and lipid peroxidation; and antioxidants. RESULTS: Of the two neonatal IH paradigms 21%/12% O2 IH resulted in the most severe outcomes, evidenced by histopathology and morphometry. CoQ10 was effective for preserving lung architecture and reduction of IH-induced oxidative stress biomarkers. In contrast, fish oil resulted in significant adverse outcomes including oversimplified alveoli, hemorrhage, reduced secondary crest formation and thickened septae. This was associated with elevated oxidants and antioxidants activities. CONCLUSIONS: Data suggest that higher FiO2 may be needed between IH episodes to curtail the damaging effects of IH, and to provide the lungs with necessary respite. The negative outcomes with fish oil supplementation suggest oxidative stress-induced lipid peroxidation.

Is carbonic anhydrase inhibition useful as a complementary therapy of Covid-19 infection?

The ongoing Covid-19 is a contagious disease, and it is characterised by different symptoms such as fever, cough, and shortness of breath. Rising concerns about Covid-19 have severely affected the healthcare system in all countries as the Covid-19 outbreak has developed at a rapid rate all around the globe. Intriguing, a clinically used drug, acetazolamide (a specific inhibitor of carbonic anhydrase, CA, EC 4.2.1.1), is used to treat high-altitude pulmonary oedema (HAPE), showing a high degree of clinical similarities with the pulmonary disease caused by Covid-19. In this context, this preliminary study aims to provide insights into some factors affecting the Covid-19 patients, such as hypoxaemia, hypoxia as well as the blood CA activity. We hypothesise that patients with Covid-19 problems could show a dysregulated acid-base status influenced by CA activity. These preliminary results suggest that the use of CA inhibitors as a pharmacological treatment for Covid-19 may be beneficial.

Effect of photobiomodulation on cellular migration and survival in diabetic and hypoxic diabetic wounded fibroblast cells.

A disrupted wound repair process often leads to the development of chronic wounds, and pose a major physical, social and economic inconvenience on patients and the public health sector. Chronic wounds are a common complication seen in diabetes mellitus (DM), and often the severity necessitates amputation of the lower limbs. Recently, there has been increasing evidence that photobiomodulation (PBM) initiates wound healing, including increased protein transcription for cell proliferation, viability, migration and tissue reepithelialisation. Here, the hypothesis that PBM at a wavelength of 660 nm and energy density of 5 J/cm2 regulates wound repair in diabetic wounded and hypoxic diabetic wounded fibroblasts by enhancing cell migration and survival was investigated. PBM increased migration and survival in diabetic wounded and hypoxic diabetic wounded fibroblasts. Our findings suggest that PBM enhances migration and survival in diabetic wounded and hypoxic diabetic wounded fibroblasts, indicating that this therapeutic method may be beneficial against chronic wounds in diabetic patients.

Rice Bran and Vitamin B6 Suppress Pathological Neovascularization in a Murine Model of Age-Related Macular Degeneration as Novel HIF Inhibitors.

Pathological neovascularization in the eye is a leading cause of blindness in all age groups from retinopathy of prematurity (ROP) in children to age-related macular degeneration (AMD) in the elderly. Inhibiting neovascularization via antivascular endothelial growth factor (VEGF) drugs has been used for the effective treatment. However, anti-VEGF therapies may cause development of chorioretinal atrophy as they affect a physiological amount of VEGF essential for retinal homeostasis. Furthermore, anti-VEGF therapies are still ineffective in some cases, especially in patients with AMD. Hypoxia-inducible factor (HIF) is a strong regulator of VEGF induction under hypoxic and other stress conditions. Our previous reports have indicated that HIF is associated with pathological retinal neovascularization in murine models of ROP and AMD, and HIF inhibition suppresses neovascularization by reducing an abnormal increase in VEGF expression. Along with this, we attempted to find novel effective HIF inhibitors from natural foods of our daily lives. Food ingredients were screened for prospective HIF inhibitors in ocular cell lines of 661W and ARPE-19, and a murine AMD model was utilized for examining suppressive effects of the ingredients on retinal neovascularization. As a result, rice bran and its component, vitamin B6 showed inhibitory effects on HIF activation and suppressed VEGF mRNA induction under a CoCl2-induced pseudo-hypoxic condition. Dietary supplement of these significantly suppressed retinal neovascularization in the AMD model. These data suggest that rice bran could have promising therapeutic values in the management of pathological ocular neovascularization.

Galectin-3 expression and secretion by tumor-associated macrophages in hypoxia promotes breast cancer progression.

Tumor-associated macrophages (TAMs) have been shown to be associated with poor prognosis of cancer and are predominately localized in the hypoxia regions of tumor. We demonstrated in this study that hypoxia increases the synthesis and secretion of galectin-3 by TAMs. The increased expression of galectin-3 in TAMs was seen to be associated with nucleation of transcription factor NF-κB through generation and activation of ROS and promoted tumor growth and metastasis in vitro and in mice through multiple molecular mechanisms. It was found that the TAMs-mediated promotion of tumor growth and metastasis in hypoxia was inhibited by administration of macrophage-depletion agent clodronate liposomal (CL) or galectin-3 inhibitor modified citric pectin (MCP) in orthotopic syngeneic mammary adenocarcinoma model and metastasis model. Co-administration of anti-angiogenesis agent sorafenib or bevacizumab with CL and MCP showed to cause stronger inhibition of tumor growth and metastasis than administration of each agent alone. These results indicate that hypoxia-induced galectin-3 expression and secretion from TAMs promotes tumor growth and metastasis. Targeting the actions of galectin-3 in hypoxia may be a potential therapeutic strategy for cancer treatment.

Effect of Infrared Low-Intensity Laser Irradiation on Lipid Peroxidation under Conditions of Experimental Circulatory Hypoxia of Visual Analyzer.

The physiological stress modeled by circulatory hypoxia activates LPO processes in various tissues. In posthypoxic period, the infrared low-intensity laser irradiation significantly decreased the chemiluminescence parameters in blood plasma, normalized the retinal levels of diene and triene conjugates, and decreased MDA in the rat brain attesting to the correcting effect of this irradiation during various types of physiological stresses.

Huperzine A, reduces brain iron overload and alleviates cognitive deficit in mice exposed to chronic intermittent hypoxia.

Chronic intermittent hypoxia (CIH) is a consequence of obstructive sleep apnea (OSA), which increases reactive oxygen species (ROS) generation, resulting in oxidative damage and neurocognitive impairment. This study was designed to determine whether abnormal iron metabolism occurs in the brain under conditions of CIH and whether Huperzine A (HuA) could improve abnormal iron metabolism and neurological damage. The mouse model of CIH was established by reducing the percentage of inspired O2 (FiO2) from 21% to 9% 20 times/h for 8 h/day, and Huperzine A (HuA, 0.1 mg/kg, i.p.) was administered during CIH exposure for 21 days. HuA significantly improved cognitive impairment and neuronal damage in the hippocampus of CIH mice via increasing the ratio of Bcl-2/Bax and inhibiting caspase-3 cleavage. HuA considerably decreased ROS levels by downregulating the high levels of NADPH oxidase (NOX 2, NOX 4) mediated by CIH. There was an overload of iron, which was characterized by high levels of ferritin (FTL and FTH) and transferrin receptor 1 (TfR1) and low levels of ferroportin 1 (FPN1) in the hippocampus of CIH mice. Decreased levels of TfR1 and FTL proteins observed in HuA treated CIH group, could reduce iron overload in hippocampus. HuA increased PSD 95 protein expression, CREB activation and BDNF protein expression to protect against synaptic plasticity impairment induced by CIH. HuA acts as an effective iron chelator to attenuate apoptosis, oxidative stress and synaptic plasticity mediated by CIH.

Synaptic Injury in the Thalamus Accompanies White Matter Injury in Hypoxia/Ischemia-Mediated Brain Injury in Neonatal Rats.

The broad spectrum of disabilities caused by white matter injury (WMI) cannot be explained simply by hypomyelination. Synaptic injury in the thalamus may be related to disabilities in WMI survivors. Neuronal injury in the thalamus has been found most commonly in autopsy cases of preterm WMI. We hypothesized that hypoxia/ischemia (HI) in neonatal rats results in synaptic abnormalities in the thalamus that contribute to disabilities in WMI survivors. We examined changes in synapses in a neonatal rat model of HI-induced WMI. Right common carotid artery ligation and hypoxia (8% oxygen for 2.5 hours (h)) were performed in three-day-old Sprague-Dawley rats. We found HI rats performed worse in the Morris water maze test than sham rats, suggesting long-term cognition impairment after HI injury. A loss of synapses in the thalamus accompanied by hypomyelination and oligodendrocytes (OLs) reduction was observed. At the ultrastructural level, reductions in active zone (AZ) length and postsynaptic density (PSD) thickness were detected at 2 weeks after HI exposure. Furthermore, increased expression of synaptophysin and PSD-95 in both groups was observed from 3 days (d) to 21 d after hypoxic/ischemic (HI) injury. PSD-95 expression was significantly lower in HI rats than in sham rats from 14 d to 21 d after HI injury, and synaptophysin expression was significantly lower in HI rats from 7 d to 14 d after HI injury. However, no significant difference in synaptophysin expression was observed between HI rats and sham rats at 21 d after HI injury. The results demonstrated synaptic abnormalities in the thalamus accompanied by hypomyelination in WMI in response to HI exposure, which may contribute to the diverse neurological defects observed in WMI patients. Although synaptic reorganization occurred as a compensatory response to HI injury, the impairments in synaptic transmission were not reversed.

Lycium barbarum polysaccharide alleviates oxygen glucose deprivation-induced PC-12 cells damage by up-regulating miR-24.

Objective: This research was aimed to detect the functions of Lycium barbarum polysaccharides (LBPs) on oxygen and glucose deprivation (OGD) injury and potential mechanisms at PC-12 cells. Methods: CCK-8, flow cytometry and reactive oxygen species (ROS) assays were used to detect OGD, LBPs and miR-24 effects on cell viability, apoptosis, and oxidative stress. MiR-24 was transfected and texted by transfection and qRT-PCR. Moreover, the related-protein levels of apoptosis, autophagy and pathways were tested by Western blotting. Results: LBPs significantly enhanced cell viability , inhibited cell apoptosis, autophagy and ROS level in OGD injury. In addition, miR-24 expression was declined in OGD-treated cells, while it was elevated when added LBPs. The preventive effects of LBPs on PC-12 cell damage induced by OGD were reversed by down-regulating miR-24. Furthermore, miR-24 inhibitor declined LBPs-induced change in Wnt/ß-catenin and JAK1/STAT3 pathways in OGD-injuried cells. Conclusions: LBPs exhibited preventive effects via up-regulating miR-122 and activating Wnt/ß-catenin and JAK1/STAT3 pathways in OGD-induced PC-12 cells.

Mitochondria-targeted Ir@AuNRs as bifunctional therapeutic agents for hypoxia imaging and photothermal therapy.

Ir(iii) complex modified gold nanorods, Ir@AuNRs, were developed as mitochondria-targeted theranostic nanoagents. Their hypoxia imaging and photothermal therapeutic properties were demonstrated in vitro and in vivo.

[The effects of Xiaotan Huayu Liqiao formula on mesenteric artery function in rats exposed to chronic intermittent hypoxia].

OBJECTIVE: To investigate the effects of Xiaotan Huayu Liqiao formula (the Chinese Medicine) on mesenteric artery function in rats exposed to chronic intermittent hypoxia (CIH), and to explore the related mechanism. METHODS: Forty-eight male SD rats were randomly divided into four groups as Normoxia, CIH, Formula+CIH and formula group. Rats were exposed to normoxia in the Normoxia and Formula group, or intermittent hypoxia in CIH or Formula+CIH group. Xiaotan Huayu Liqiao formula was given at 24g/kg by intragastric administration before intermittent hypoxia exposure. The pathological changes of mesenteric artery were determined by HE staining, and the relaxation of mesenteric artery (induced by acetylcholine(ACh) and L-arginine(L-Arg)) was recorded by microvascular ring technique. Serums of all rats were collected (0 d and 21 d) and the content of NO was detected by ELISA. The levels of endothelial nitric oxide synthase (eNOS) and p-eNOS were measured by Western blot. RESULTS: Compared with Normoxia group, the mesenteric arterial endothelial injury and media thickening were observed and the relaxation of mesenteric artery was significantly reduced in rats exposed to CIH. The level of NO in serum and the ratio of p-eNOS/eNOS were also decreased in the CIH group. Xiaotan Huayu Liqiao formula administration improved the pathologic changes and dilatation function of mesenteric artery, increased the levels of NO and p-eNOS. Compared with Normoxia group,all the results were not observed significant difference in Formula group. CONCLUSION: Xiaotan Huayu Liqiao formula increased the bioavailability of NO, and ameliorated the CIH induced mesenteric artery function injury.

The combined effects of salinity, hypoxia, and oil exposure on survival and gene expression in developing sheepshead minnows, Cyprinodon variegatus.

The 2010 Deepwater Horizon oil spill released approximately 780 million liters of crude oil contaminating coastal habitats from Texas to Florida which are important habitats for many fish species during early life stages. These diverse habitats are also prone to rapid fluctuations in water quality, such as dissolved oxygen concentration and salinity. The consequence of combined exposure to crude oil and suboptimal environmental conditions during early life stage development of fish is still largely unknown. The objective of this project was to investigate the impacts of exposure to crude oil in combination with varying environmental stressors on developing Cyprinodon variegatus survival, growth, and gene expression. Three life stages (embryonic, post-hatch, and post-larval) were exposed to four nominal concentrations (6.25%, 12.5%, 50% and 100% with actual polycyclic aromatic hydrocarbon (PAH) concentrations ranging from 0 to 512 µg/L) of high energy water accommodated fractions (HEWAF) under different oxic (2.0 or >5.0 mg/L) and salinity (10 or 30 ppt) regimes at 30 °C for 48 h. We found that the post-larval developmental stage was the most sensitive to oil toxicity. Median lethal concentrations during the post-larval exposures followed a treatment-dependent pattern with the highest mortality observed under hypoxic-high salinity conditions (64.55 µg/L). Real-time PCR analysis identified down regulation of target genes, encoding cytochrome P450-1α (cyp1a1), erythropoietin (epo), and the aryl hydrocarbon receptor nuclear translocator (arnt1) only when oil exposure occurred under hypoxic-high salinity conditions in treatments with PAH concentrations greater than 226 µg/L. The target genes measured in this experiment are involved in the aryl hydrocarbon receptor signaling pathway which modulates metabolism of PAHs (a major component of crude oil), and the hypoxia inducible 1-α signaling pathway which is responsible for resilience to hypoxic stress, and it is known that disruption of these pathways can lead to an array of acute and chronic effects. Our results indicated that sheepshead minnow are most sensitive to oil exposure during the post-larval developmental stage. Survival data from this age-stage also indicate that oil toxicity response is exacerbated in hypoxic and high salinity environments. The increased mortality observed during the post-larval developmental stage might be attributed to the suppression of the aryl hydrocarbon receptor signaling and the hypoxia inducible 1-α signaling pathways which is evident in by the down-regulated expression of cyp1a1, epo, and arnt1. These findings provide more information about interactions between oil and abiotic factors which enable us to make better assumptions of the ecological impacts of DWH on coastal estuaries.

Hypoxia and reduced salinity exacerbate the effects of oil exposure on sheepshead minnow (Cyprinodon variegatus) reproduction.

Estuaries of the northern Gulf of Mexico are dynamic environments, with fluctuations in salinity and dissolved oxygen, including areas of seasonal hypoxia. Fish that reside and reproduce in these estuaries, including sheepshead minnow (Cyprinodon variegatus; SHM), were at significant risk of oil exposure following the Deepwater Horizon oil spill. It is poorly understood how differences in environmental conditions during oil exposure impact its toxicity. The present study investigated the effects of crude oil high-energy water accommodated fraction (HEWAF) on SHM reproduction in three environmental scenarios (normoxic, hypoxic, and hypoxic with low salinity) to determine if differences in salinity (brackish vs low salinity) and dissolved oxygen (normoxia vs hypoxia) could exacerbate the effects of HEWAF-derived polycyclic aromatic hydrocarbons (PAHs). We observed that HEWAF exposure significantly increased liver somatic index of SHM compared to control, but this effect was not exacerbated by hypoxia or low salinity. HEWAF exposure also significantly decreased egg production and egg fertilization rate, but only in the hypoxic and hypoxic with low salinity scenarios. A significant correlation existed between body burdens of PAHs and reproductive endpoints, providing substantial evidence that oil exposure reduced reproductive capacity in SHM, across a range of environmental conditions. These data suggest that oil spill risk assessments that fail to consider other environmental stressors (i.e. hypoxia and salinity) may be underestimating risk.

In Situ Oxygenic Nanopods Targeting Tumor Adaption to Hypoxia Potentiate Image-Guided Photothermal Therapy.

Tumor adaption to hypoxic stress not only plays a crucial role in tumor malignancy but also can protect cancer cells from therapeutic interventions. Hence, therapeutic strategies attenuating tumor hypoxia in conjunction with conventional therapies may be an ideal approach. Here, we report the application of in situ oxygenic carbon nano-onion (CNO)/manganese oxide nanopods (iOCOMs) as novel theranostic photothermal transducers to neutralize the oncogenic influence of the hypoxic tumor microenvironment (TME). The developed onion-ring-shaped carbon nanoparticles or carbon nano-onions (CNOs) and iOCOM nanopods (CNO embedded in MnO2 nanosheets) were biologically stable and nontoxic and showed photothermal activity under near-infrared laser irradiation (808 nm). In addition, iOCOM assisted in the dismutation of hydrogen peroxide (H2O2), a potentially toxic reactive oxygen species that is secreted excessively by cancer cells in the hypoxic TME, resulting in in situ oxygenation and repolarization of the hypoxic TME to normoxia. The manganese ions released from iOCOM during the catalysis of H2O2 assisted in TME-responsive T1 magnetic resonance imaging (MRI). The in situ oxygenation by iOCOM in the hypoxic TME downregulated the secretion of hypoxia-inducible factor 1-α, which subsequently interfered with the cancer cell proliferation, favored tumor angiogenesis, and most importantly prevented metastatic epithelial-to-mesenchymal transition of tumor cells. Collectively, this work presents a new paradigm for antitumor strategies by targeting the tumor adaption to hypoxia in combination with photothermal therapy.