Nox2 and p47phox modulate compensatory growth of primary collateral arteries

The role of NADPH oxidase (Nox) in both the promotion and impairment of compensatory collateral growth remains controversial because the specific Nox and reactive oxygen species involved are unclear. The aim of this study was to identify the primary Nox and reactive oxygen species associated with early stage compensatory collateral growth in young, healthy animals. Ligation of the feed arteries that form primary collateral pathways in rat mesentery and mouse hindlimb was used to assess the role of Nox during collateral growth. Changes in mesenteric collateral artery Nox mRNA expression determined by real-time PCR at 1, 3, and 7 days relative to same-animal control arteries suggested a role for Nox subunits Nox2 and p47phox. Administration of apocynin or Nox2ds-tat suppressed collateral growth in both rat and mouse models, suggesting the Nox2/p47phox interaction was involved. Functional significance of p47phox expression was assessed by evaluation of collateral growth in rats administered p47phox small interfering RNA and in p47phox−/− mice. Diameter measurements of collateral mesenteric and gracilis arteries at 7 and 14 days, respectively, indicated no significant collateral growth compared with control rats or C57BL/6 mice. Chronic polyethylene glycol-conjugated catalase administration significantly suppressed collateral development in rats and mice, implying a requirement for H2O2. Taken together, these results suggest that Nox2, modulated at least in part by p47phox, mediates early stage compensatory collateral development via a process dependent upon peroxide generation. These results have important implications for the use of antioxidants and the development of therapies for peripheral arterial disease

Delayed effects of acute radiation exposure (DEARE) in a murine model of the hematopoietic acute radiation syndrome: Multiple-organ injury consequent to total body irradiation

Introduction. Victims of radiation exposure from terrorist activity, radiation accidents or radiologic warfare will face a variety of acute and chronic organ injuries requiring multi-faceted approaches to treatment. The hematopoietic system is the most sensitive tissue to radiation damage, resulting in the hematopoietic acute radiation syndrome (H-ARS) after exposures of 2-10 Gy in mice. If untreated, H-ARS results in death within weeks from opportunistic infection and/or hemorrhage due to loss of neutrophils and platelets, respectively. However, survivors of ARS are plagued months to years later in life by delayed effects of acute radiation exposure (DEARE), a myriad of chronic illnesses affecting multiple organ systems believed to be due to persistent systemic oxidative stress, inflammation, fibrosis and loss of stem cell self-renewal. Fibrosis and collagen deposition disrupt both normal tissue structure and function and are common to organs with late radiation injury including the kidney and heart after radiation doses >15Gy, but have not been shown to exist after doses as low as those used in the H-ARS model (8Gy). The goal of this study was to determine the extent, if any, of heart and kidney DEARE in survivors of H-ARS. Methods. Mice (male and female C57BL/6) received total body irradiation (TBI; LD50/30 to LD70/30) and kidney and heart were harvested at 9 and 21 months from the H-ARS survivor mice. Tissues were fixed in neutral buffered formalin, paraffin embedded and sectioned, then stained with hematoxylin/eosin (H&E), trichrome, or picosirius red. Serum was collected at 4.3, 9, and 21 months post-TBI and analyzed for blood urea nitrogen (BUN) as an indicator of kidney function. Total RNA was purified from heart and relative changes in NADPH oxidase 2 (Nox2) mRNA expression were assessed by quantitative real-time PCR. Results/Significance. Compared to age-matched non-irradiated controls (NI), renal pathology at 9 months post-TBI was manifest primarily as enlargement of Bowman’s capsule and glomerosclerosis along with limited interstitial fibrosis. By 21 months there was progression of these pathologies as well as extensive interstitial fibrosis, tubular atrophy, cysts, and atubular glomeruli, all of which were more pronounced in TBI mice compared to NI. Consistent with the renal pathology, BUN in TBI mice was significantly increased at 9 and 21 months post-TBI vs. 4.3 months, but normal in NI mice at all time points. In the heart, pericardial, perivascular and interstitial fibrosis were observed at 9 months with increased severity at 21 months post-TBI compared to NI. The perivascular fibrosis was associated with increased medial layer collagen and apparent loss of vascular smooth muscle cells. Nox2 mRNA in heart was increased at 9 and 21 months post-TBI, indicating an increase in oxidant stress. To our knowledge, such striking heart and kidney damage has not been documented after radiation doses as low as those in our H-ARS model (~8Gy) and indicate that DEARE is a concern for individuals exposed to radiation doses previously thought to not elicit late effects

Delayed effects of acute radiation exposure on the cardiovascular system using a murine model of the hematopoietic acute radiation syndrome

poster abstractIntroduction. Exposure to high level radiation from accidents or belligerent activities results in acute and chronic organ damage. The hematopoietic system is the most sensitive organ to radiation damage (2-10 Gy) and results in the hematopoietic acute radiation syndrome (H-ARS). Survivors of H-ARS are plagued months to years later with delayed effects of acute radiation exposure (DEARE), characterized by chronic illnesses affecting multiple organ systems. Previous results using the murine H-ARS model showed numerous kidney and heart DEARErelated pathologies similar to humans, including tissue fibrosis and elevated blood urea nitrogen. The goal of this study was to utilize the murine H-ARS model to determine possible roles for abnormal iron metabolism, inflammation, oxidant stress, and senescence in the development of cardiac DEARE. Methods. Mice (C57BL/6; 12 week-old) received total body irradiation (TBI: ~8.5-8.7 Gy, 137Cs, LD50to LD70) and hearts were harvested at various times post-TBI from H-ARS survivors. Paraffin tissue sections were stained with hematoxylin/eosin or Perls Prussian Blue, or reacted with a macrophage-specific antibody (F4/80). Total RNA was purified from fresh tissue and changes in mRNA expression were assessed by real-time PCR for the senescence marker p16 and NADPH oxidase subunits Nox2, Nox4, or p47phox. Results/Significance. Compared to age-matched non-irradiated controls (NI), tissue iron deposits were increased in irradiated (IR) hearts at 4 months, and progressively declined with time post-TBI. Numbers of macrophages were greater in IR vs. NI sections at all time points and decreased with time post-TBI. Nox2 and Nox4 mRNA expression was increased at both 9 and 21 months post-TBI, but p47phox increased only at 21 months. Expression of p16 in IR heart was increased at 7, but not at 22 months post-TBI. Taken together, the results indicate abnormal iron metabolism, inflammation, oxidant stress, and early senescence may contribute to development of cardiac DEARE

Amino-diol borate complexation for controlling transport phenomena of penetrant molecules into polymeric matrices

The development of new high performance materials, coatings, composites and adhesives relies on insight into the origin of material performance on a molecular level. This paper explores a new type of epoxy-amine-borate (EAB) hybrid material for control of penetrant solvent molecules into cross-linked thermoset polymer networks

Novel Method to Assess Arterial Insufficiency in Rodent Hindlimb

BACKGROUND: Lack of techniques to assess maximal blood flow capacity thwarts the use of rodent models of arterial insufficiency to evaluate therapies for intermittent claudication. We evaluated femoral vein outflow (VO) in combination with stimulated muscle contraction as a potential method to assess functional hind limb arterial reserve and therapeutic efficacy in a rodent model of subcritical limb ischemia. MATERIALS AND METHODS: VO was measured with perivascular flow probes at rest and during stimulated calf muscle contraction in young, healthy rats (Wistar Kyoto, WKY; lean Zucker rats, LZR) and rats with cardiovascular risk factors (spontaneously hypertensive [SHR]; obese Zucker rats [OZR]) with acute and/or chronic femoral arterial occlusion. Therapeutic efficacy was assessed by administration of Ramipril or Losartan to SHR after femoral artery excision. RESULTS: VO measurement in WKY demonstrated the utility of this method to assess hind limb perfusion at rest and during calf muscle contraction. Although application to diseased models (OZR and SHR) demonstrated normal resting perfusion compared with contralateral limbs, a significant reduction in reserve capacity was uncovered with muscle stimulation. Administration of Ramipril and Losartan demonstrated significant improvement in functional arterial reserve. CONCLUSIONS: The results demonstrate that this novel method to assess distal limb perfusion in small rodents with subcritical limb ischemia is sufficient to unmask perfusion deficits not apparent at rest, detect impaired compensation in diseased animal models with risk factors, and assess therapeutic efficacy. The approach provides a significant advance in methods to investigate potential mechanisms and novel therapies for subcritical limb ischemia in preclinical rodent models

Design and Optimisation of a Microwave Reactor for Kilo-Scale Polymer Synthesis

Current industrial production of polymer resins is generally undertaken in large multi-tonne stirred tank reactors. These are characterised by relatively slow heating and cooling cycles, resulting in long vessel cycle times and extended production campaigns. In this work we present a design for a hybrid microwave/oil jacket proof of concept system capable of producing up to 4.1 kg of polymer resin per batch. By exploiting rapid volumetric heating effects of microwave energy at 2.45GHz, we have optimised the synthetic regime, such that a 3.7 kg batch of polyester resin pre-polymer can be made in only 8 hours 20 minutes, with higher molecular weight (Mn 2,100) compared to the conventional process taking 22 hours 15 minutes (Mn 1,200), yielding an increase in synthesis rate of at least 265. The increase in polymer molecular weight also suggests a higher conversion was achieved over a shorter time scale

Design and optimisation of a microwave reactor for kilo-scale polymer synthesis

Current industrial production of polymer resins is generally undertaken in large multi-tonne stirred tank reactors. These are characterised by relatively slow heating and cooling cycles, resulting in long vessel cycle times and extended production campaigns. In this work we present a design for a hybrid microwave/oil jacket proof of concept system capable of producing up to 4.1?kg of polymer resin per batch. By exploiting rapid volumetric heating effects of microwave energy at 2.45?GHz, we have optimised the synthetic regime, such that a 3.7?kg batch of polyester resin pre-polymer can be made in only 8?h 20?min, with higher molecular weight (Mn 2100) compared to the conventional process taking 22?h 15?min (Mn 1200), yielding an increase in synthesis rate of at least 265%. The increase in polymer molecular weight also suggests a higher conversion was achieved over a shorter time scale

A Potential Role for Excess Tissue Iron in Development of Cardiovascular Delayed Effects of Acute Radiation Exposure

Murine hematopoietic-acute radiation syndrome (H-ARS) survivors of total body radiation (TBI) have a significant loss of heart vessel endothelial cells, along with increased tissue iron, as early as 4 months post-TBI. The goal of the current study was to determine the possible role for excess tissue iron in the loss of coronary artery endothelial cells. Experiments utilized the H-ARS mouse model with gamma radiation exposure of 853 cGy (LD50/30) and time points from 1 to 12 weeks post-TBI. Serum iron was elevated at 1 week post-TBI, peaked at 2 weeks, and returned to non-irradiated control values by 4 weeks post-TBI. A similar trend was seen for transferrin saturation, and both results correlated inversely with red blood cell number. Perls’ Prussian Blue staining used to detect iron deposition in heart tissue sections showed myocardial iron was present as early as 2 weeks following irradiation. Pretreatment of mice with the iron chelator deferiprone decreased tissue iron, but not serum iron, at 2 weeks. Coronary artery endothelial cell density was significantly decreased as early as two weeks vs. non-irradiated controls (P<0.05), and the reduced density persisted to 12 weeks after irradiation. Deferiprone treatment of irradiated mice prevented the decrease in endothelial cell density at 2 and 4 weeks post-TBI compared to irradiated, non-treated mice (P<0.03). Taken together, the results suggest excess tissue iron contributes to endothelial cell loss early following TBI and may be a significant event impacting the development of delayed effects of acute radiation exposure

Cardiac and Renal Delayed Effects of Acute Radiation Exposure: Organ Differences in Vasculopathy, Inflammation, Senescence and Oxidative Balance

We have previously shown significant pathology in the heart and kidney of murine hematopoietic-acute radiation syndrome (H-ARS) survivors of 8.7-9.0 Gy total-body irradiation (TBI). The goal of this study was to determine temporal relationships in the development of vasculopathy and the progression of renal and cardiovascular delayed effects of acute radiation exposure (DEARE) at TBI doses less than 9 Gy and to elucidate the potential roles of senescence, inflammation and oxidative stress. Our results show significant loss of endothelial cells in coronary arteries by 4 months post-TBI (8.53 or 8.72 Gy of gamma radiation). This loss precedes renal dysfunction and interstitial fibrosis and progresses to abnormalities in the arterial media and adventitia and loss of coronary arterioles. Major differences in radiation-induced pathobiology exist between the heart and kidney in terms of vasculopathy progression and also in indices of inflammation, senescence and oxidative imbalance. The results of this work suggest a need for different medical countermeasures for multiple targets in different organs and at various times after acute radiation injury to prevent the progression of DEARE

Delayed Effects of Acute Radiation Exposure in a Murine Model of the H-ARS: Multiple-Organ Injury Consequent to <10 Gy Total Body Irradiation

The threat of radiation exposure from warfare or radiation accidents raises the need for appropriate animal models to study the acute and chronic effects of high dose rate radiation exposure. The goal of this study was to assess the late development of fibrosis in multiple organs (kidney, heart, and lung) in survivors of the C57BL/6 mouse model of the hematopoietic-acute radiation syndrome (H-ARS). Separate groups of mice for histological and functional studies were exposed to a single uniform total body dose between 8.53 and 8.72 Gy of gamma radiation from a Cs radiation source and studied 1-21 mo later. Blood urea nitrogen levels were elevated significantly in the irradiated mice at 9 and 21 mo (from ∼22 to 34 ± 3.8 and 69 ± 6.0 mg dL, p < 0.01 vs. non-irradiated controls) and correlated with glomerosclerosis (29 ± 1.8% vs. 64 ± 9.7% of total glomeruli, p < 0.01 vs. non-irradiated controls). Glomerular tubularization and hypertrophy and tubular atrophy were also observed at 21 mo post-total body irradiation (TBI). An increase in interstitial, perivascular, pericardial and peribronchial fibrosis/collagen deposition was observed from ∼9-21 mo post-TBI in kidney, heart, and lung of irradiated mice relative to age-matched controls. Echocardiography suggested decreased ventricular volumes with a compensatory increase in the left ventricular ejection fraction. The results indicate that significant delayed effects of acute radiation exposure occur in kidney, heart, and lung in survivors of the murine H-ARS TBI model, which mirrors pathology detected in larger species and humans at higher radiation doses focused on specific organs