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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Lin28b stimulates the reprogramming of rat Müller glia to retinal progenitors

In lower-order vertebrates, Müller glia exhibit characteristics of retinal progenitor cells, while in higher vertebrates, such as mammals, the regenerative capacity of Müller glia is limited. Recently, we reported that Lin28b promoted the trans-differentiation of Müller cells to rod photoreceptor and bipolar cells in the retina of retinitis pigmentosa rat model, whereas it is unclear whether Lin28b can stimulate the reprogramming of Müller glia in vitro for transplantation into a damaged retina. In the present study, Long-Evens rat Müller glia were infected with Adeno-Lin28b or Adeno-GFP. Over-expression of Lin28b in isolated rat Müller glia resulted in the suppression of GFAP expression, enhancement of cell proliferation and a significant increase of the expression of retinal progenitor markers 5 days after infection. Moreover, Lin28b caused a significant reduction of the Let-7 family of microRNAs. Following sub-retinal space transplantation, Müller glia-derived retinal progenitors improved b-wave amplification of 30d Royal College of Surgeons retinitis pigmentosa model (RCS-P+) rats, as detected by electroretinography (ERG) recordings. Taken together, these data suggest that the up-regulation of Lin28b expression facilitated the reprogramming of Müller cells toward characteristics of retinal progenitors. - Highlights: • Lin28b reprograms Müller glia to retinal progenitors. • Let-7 micrRNAs are suppressed by Lin28b. • Transplantation of reprogrammed Müller glia restores retinal function.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

FPR1 gene silencing suppresses cardiomyocyte apoptosis and ventricular remodeling in rats with ischemia/reperfusion injury through the inhibition of MAPK signaling pathway

Ischemia/reperfusion (I/R) injury, one of the leading health problems in the world, is defined as a cause of cardiomyocytes death. In the present study, we investigate the role of formyl peptide receptor 1 (FPR1) in cardiomyocyte apoptosis and ventricular remodeling of I/R injury rats and the underlying mechanism involving mitogen-activated protein kinase (MAPK) signaling pathway. The important differentially expressed genes (DEGs) in I/R injury were screened out and downstream pathways affected by DEGs were predicted. We grouped 90 rats into sham, I/R, NC siRNA, FRP1 siRNA, empty vector, and FRP1 vector groups and established a model of I/R injury in rats. CVF value, myocardial infarct areas and positive expression rate of FPR1 and MAPK were detected. Levels of FPR1 and MAPK pathway-related genes were determined by RT-qPCR and western blot analysis. MTT assay was performed to evaluate cell proliferation and flow cytometry to evaluate cell cycle progression and apoptosis. GSE19804 and GSE27262 were screened from Gene Expression Omnibus database. FPR1 was higher in patients with I/R injury and activate the MAPK signaling pathway. FRP1 gene silencing decreased CVF value, infarct area, apoptotic index, positive expression rates of FPR1 and MAPK, decreased FPR1, p38, ERK, JNK, MMP-2, TIMP-2, NF-kB, Bax, p-p38, p-ERK, and p-JNK levels, increased Bcl-2 level, promoted cell proliferation and cell cycle progression, and inhibited cell apoptosis rate. Overall, our study demonstrates that the silencing of FPR1 gene depresses inflammation, cardiomyocyte apoptosis and ventricular remodeling in rats with I/R injury through the suppressing the activation of the MAPK signaling pathway.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1998

Hindlimb unloading of growing rats: a model for predicting skeletal changes during space flight

A model that uses hindlimb unloading of rats was developed to study the consequences of skeletal unloading and reloading as occurs during and following space flight. Studies using the model were initiated two decades ago and further developed at National Aeronautics and Space Administration (NASA)-Ames Research Center. The model mimics some aspects of exposure to microgravity by removing weightbearing loads from the hindquarters and producing a cephalic fluid shift. Unlike space flight, the forelimbs remain loaded in the model, providing a useful internal control to distinguish between the local and systemic effects of hindlimb unloading. Rats that are hindlimb unloaded by tail traction gain weight at the same rate as pairfed controls, and glucocorticoid levels are not different from controls, suggesting that systemic stress is minimal. Unloaded bones display reductions in cancellous osteoblast number, cancellous mineral apposition rate, trabecular bone volume, cortical periosteal mineralization rate, total bone mass, calcium content, and maturation of bone mineral relative to controls. Subsequent studies reveal that these changes also occur in rats exposed to space flight. In hindlimb unloaded rats, bone formation rates and masses of unloaded bones decline relative to controls, while loaded bones do not change despite a transient reduction in serum 1,25-dihydroxyvitamin D (1,25D) concentrations. Studies using the model to evaluate potential countermeasures show that 1,25D, growth hormone, dietary calcium, alendronate, and muscle stimulation modify, but do not completely correct, the suppression of bone growth caused by unloading, whereas continuous infusion of transforming growth factor-beta2 or insulin-like growth factor-1 appears to protect against some of the bone changes caused by unloading. These results emphasize the importance of local as opposed to systemic factors in the skeletal response to unloading, and reveal the pivotal role that osteoblasts play in the response to gravitational loading. The hindlimb unloading model provides a unique opportunity to evaluate in detail the physiological and cellular mechanisms of the skeletal response to weightbearing loads, and has proven to be an effective model for space flight.

Non-NASA Center↗
NASA NTRS1998

Skeletal muscle afferent regulation of bioassayable growth hormone in the rat pituitary

There are forms of growth hormone (GH) in the plasma and pituitary of the rat and in the plasma of humans that are undetected by presently available immunoassays (iGH) but can be measured by bioassay (bGH). Although the regulation of iGH release is well documented, the mechanism(s) of bGH release is unclear. On the basis of changes in bGH and iGH secretion in rats that had been exposed to microgravity conditions, we hypothesized that neural afferents play a role in regulating the release of these hormones. To examine whether bGH secretion can be modulated by afferent input from skeletal muscle, the proximal or distal ends of severed hindlimb fast muscle nerves were stimulated ( approximately 2 times threshold) in anesthetized rats. Plasma bGH increased approximately 250%, and pituitary bGH decreased approximately 60% after proximal nerve trunk stimulation. The bGH response was independent of muscle mass or whether the muscles were flexors or extensors. Distal nerve stimulation had little or no effect on plasma or pituitary bGH. Plasma iGH concentrations were unchanged after proximal nerve stimulation. Although there may be multiple regulatory mechanisms of bGH, the present results demonstrate that the activation of low-threshold afferents from fast skeletal muscles can play a regulatory role in the release of bGH, but not iGH, from the pituitary in anesthetized rats.

Non-NASA Center↗
NASA NTRS2004

Environmental impacts on the developing CNS: CD15, NCAM-L1, and GFAP expression in rat neonates exposed to hypergravity

We have previously reported that the developing rat cerebellum is affected by hypergravity exposure. The effect is observed during a period of both granule and glial cell proliferation and neuronal migration in the cerebellum and coincides with changes in thyroid hormone levels. The present study begins to address the molecular mechanisms involved in the cerebellar response to hypergravity. Specifically, the study focuses on the expression of cerebellar proteins that are known to be directly involved in cell-cell interactions [protein expressing 3-fucosyl-N-acetyl-lactosamine antigen (CD15), neuronal cell adhesion molecule (NCAM-L1)] and those that affect cell-cell interactions indirectly [glial fibrillary acidic protein (GFAP)] in rat neonates exposed to centrifuge-produced hypergravity. Cerebellar mass and protein expression in rat neonates exposed to hypergravity (1.5 G) from gestational day (G) 11 to postnatal day (P) 30 were compared at one of six time points between P6 and P30 against rat neonates developing under normal gravity. Proteins were analyzed by quantitative western blots of cerebellar homogenates prepared from male or female neonates. Cerebellar size was most clearly reduced in male neonates on P6 and in female neonates on P9, with a significant gender difference; differences in cerebellar mass remained significant even when change in total body mass was factored in. Densitometric analysis of western blots revealed both quantitative and temporal changes in the expression of selected cerebellar proteins that coincided with changes in cerebellar mass and were gender-specific. In fact, our data indicated certain significant differences even between male and female control animals. A maximal decrease in expression of CD15 was observed in HG females on P9, coinciding with maximal change in their cerebellar mass. A shift in the time-course of NCAM-L1 expression resulted in a significant increase in NCAM-L1 in HG males on P18, an isolated time at which cerebellar mass does not significantly differ between HG and SC neonates. A maximal decrease in expression of GFAP was observed in HG males on P6, coinciding with maximal change in their cerebellar mass. Altered expression of cerebellar proteins is likely to affect a number of developmental processes and contribute to the structural and functional alterations seen in the CNS developing under altered gravity. Our data suggest that both cerebellar development and its response to gravitational manipulations differ in males and females. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Program Fundamental Space Biology↗
DOE OSTI2010

PhyloChip microarray analysis reveals altered gastrointestinal microbial communities in a rat model of colonic hypersensitivity

Irritable bowel syndrome (IBS) is a chronic, episodic gastrointestinal disorder that is prevalent in a significant fraction of western human populations; and changes in the microbiota of the large bowel have been implicated in the pathology of the disease. Using a novel comprehensive, high-density DNA microarray (PhyloChip) we performed a phylogenetic analysis of the microbial community of the large bowel in a rat model in which intracolonic acetic acid in neonates was used to induce long lasting colonic hypersensitivity and decreased stool water content and frequency, representing the equivalent of human constipation-predominant IBS. Our results revealed a significantly increased compositional difference in the microbial communities in rats with neonatal irritation as compared with controls. Even more striking was the dramatic change in the ratio of Firmicutes relative to Bacteroidetes, where neonatally irritated rats were enriched more with Bacteroidetes and also contained a different composition of species within this phylum. Our study also revealed differences at the level of bacterial families and species. The PhyloChip is a useful and convenient method to study enteric microflora. Further, this rat model system may be a useful experimental platform to study the causes and consequences of changes in microbial community composition associated with IBS.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2010

Divergent actions of the pyrethroid insecticides S-bioallethrin, tefluthrin, and deltamethrin on rat Na{sub v}1.6 sodium channels

We expressed rat Na{sub v}1.6 sodium channels in combination with the rat {beta}{sub 1} and {beta}{sub 2} auxiliary subunits in Xenopus laevis oocytes and evaluated the effects of the pyrethroid insecticides S-bioallethrin, deltamethrin, and tefluthrin on expressed sodium currents using the two-electrode voltage clamp technique. S-Bioallethrin, a type I structure, produced transient modification evident in the induction of rapidly decaying sodium tail currents, weak resting modification (5.7% modification at 100 {mu}M), and no further enhancement of modification upon repetitive activation by high-frequency trains of depolarizing pulses. By contrast deltamethrin, a type II structure, produced sodium tail currents that were {approx} 9-fold more persistent than those caused by S-bioallethrin, barely detectable resting modification (2.5% modification at 100 {mu}M), and 3.7-fold enhancement of modification upon repetitive activation. Tefluthrin, a type I structure with high mammalian toxicity, exhibited properties intermediate between S-bioallethrin and deltamethrin: intermediate tail current decay kinetics, much greater resting modification (14.1% at 100 {mu}M), and 2.8-fold enhancement of resting modification upon repetitive activation. Comparison of concentration-effect data showed that repetitive depolarization increased the potency of tefluthrin {approx} 15-fold and that tefluthrin was {approx} 10-fold more potent than deltamethrin as a use-dependent modifier of Na{sub v}1.6 sodium channels. Concentration-effect data from parallel experiments with the rat Na{sub v}1.2 sodium channel coexpressed with the rat {beta}{sub 1} and {beta}{sub 2} subunits in oocytes showed that the Na{sub v}1.6 isoform was at least 15-fold more sensitive to tefluthrin and deltamethrin than the Na{sub v}1.2 isoform. These results implicate sodium channels containing the Na{sub v}1.6 isoform as potential targets for the central neurotoxic effects of pyrethroids.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

NMR-based metabonomic analysis of the hepatotoxicity induced by combined exposure to PCBs and TCDD in rats

A metabonomic approach using {sup 1}H NMR spectroscopy was adopted to investigate the metabonomic pattern of rat urine after oral administration of environmental endocrine disruptors (EDs) polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) alone or in combination and to explore the possible hepatotoxic mechanisms of combined exposure to PCBs and TCDD. {sup 1}H NMR spectra of urines collected 24 h before and after exposure were analyzed via pattern recognition by using principal component analysis (PCA). Serum biochemistry and liver histopathology indicated significant hepatotoxicity in the rats of the combined group. The PCA scores plots of urinary {sup 1}H NMR data showed that all the treatment groups could be easily distinguished from the control group, so could the PCBs or TCDD group and the combined group. The loadings plots of the PCA revealed remarkable increases in the levels of lactate, glucose, taurine, creatine, and 2-hydroxy-isovaleric acid and reductions in the levels of 2-oxoglutarate, citrate, succinate, hippurate, and trimethylamine-N-oxide in rat urine after exposure. These changes were more striking in the combined group. The changed metabolites may be considered possible biomarker for the hepatotoxicity. The present study demonstrates that combined exposure to PCBs and TCDD induced significant hepatotoxicity in rats, and mitochondrial dysfunction and fatty acid metabolism perturbations might contribute to the hepatotoxicity. There was good conformity between changes in the urine metabonomic pattern and those in serum biochemistry and liver histopathology. These results showed that the NMR-based metabonomic approach may provide a promising technique for the evaluation of the combined toxicity of EDs.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2002

Body mass, energy intake, and water consumption of rats and humans during space flight

Alteration of metabolism has been suggested as a major limiting factor to long-term space flight. In humans and primates, a negative energy balance has been reported. The metabolic response of rats to space flight has been suggested to result in a negative energy balance. We hypothesized that rats flown in space would maintain energy balance as indicated by maintenance of caloric intake and body mass gain. Further, the metabolism of the rat would be similar to that of laboratory-reared animals. We studied the results from 15 space flights lasting 4 to 19 d. There was no difference in average body weight (206 +/- 13.9 versus 206 +/- 14.8 g), body weight gain (5.8 +/- 0.48 versus 5.9 +/- 0.56 g/d), caloric intake (309 +/- 21.0 versus 309 +/- 20.1 kcal/kg of body mass per day), or water intake (200 +/- 8.6 versus 199 +/- 9.3 mL/kg of body mass per day) between flight and ground control animals. Compared with standard laboratory animals of similar body mass, no differences were noted. The observations suggested that the negative balance observed in humans and non-human primates may be due to other factors in the space-flight environment.

Non-NASA Center↗
NASA NTRS2002

Growth and maturational changes in dense fibrous connective tissue following 14 days of rhGH supplementation in the dwarf rat

The purpose of this study was to investigate the impact of recombinant human growth hormone (rhGH) on patella tendon (PT), medial collateral ligament (MCL), and lateral collateral ligament (LCL) on collagen growth and maturational changes in dwarf GH-deficient rats. Twenty male Lewis mutant dwarf rats, 37 days of age, were randomly assigned to Dwarf + rhGH (n = 10) and Dwarf + vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt twice daily for 14 days. rhGH administration stimulated dense fibrous connective tissue growth, as demonstrated by significant increases in hydroxyproline specific activity and significant decreases in the non-reducible hydroxylysylpyridinoline (HP) collagen cross-link contents. The increase in the accumulation of newly accreted collagen was 114, 67, and 117% for PT, MCL, and LCL, respectively, in 72 h. These findings suggest that a short course rhGH treatment can affect the rate of new collagen production. However, the maturation of the tendon and ligament tissues decreased 18-25% during the rapid accumulation of de novo collagen. We conclude that acute rhGH administration in a dwarf rat can up-regulate new collagen accretion in dense fibrous connective tissues, while causing a reduction in collagen maturation. Copyright 2002 Elsevier Science Ltd.

NASA Discipline Musculoskeletal↗
DOE OSTI2018

Aerobic exercise training decreases cereblon and increases AMPK signaling in the skeletal muscle of STZ-induced diabetic rats

Highlights: • STZ-induced diabetes increased levels of CRBN protein in the skeletal muscle. • Aerobic exercise training attenuates level of CRBN protein and increases AMPK signaling in skeletal muscle. • CRBN is a regulator of exercise-mediated anti-diabetic effect. Cereblon (CRBN) has been reported as a negative regulator of adenosine monophosphate-activated protein kinase (AMPK). Aerobic exercise training has been shown to increase AMPK, which resulted in glucose regulation in skeletal muscle. However, the expression level of CRBN and its association with the physiological modulation of glucose are still unclear. Male Sprague-Dawley rats (5-week-old, n = 18) were assigned to control, streptozotocin (STZ, 65 mg/kg)-induced diabetic group, and STZ + exercise (STZ + EXE) group with six rats in each group. Rats in the STZ + EXE group exercised by treadmill running (20 m/min, 60 min, 4 times/week) for 8 weeks. Compared with the STZ group, blood glucose was significantly decreased in the STZ + EXE group. The skeletal muscle of rats in the STZ + EXE group showed a significant decrease in CRBN levels and an increase in AMPK, protein kinase B, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, fibronectin type III domain-containing protein 5, glucose transporter type 4, superoxide dismutase 1, and uncoupling protein 3 levels. These results suggest that CRBN is a potential regulator of glucose homeostasis in the skeletal muscle. Moreover, our results suggest that aerobic exercise training may provide an important physiological treatment for type 1 diabetes by decreasing CRBN and increasing AMPK signaling in skeletal muscle.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Ramalin, an antioxidant compound derived from Antarctic lichen, prevents progression of liver fibrosis induced by dimethylnitrosamine (DNM) in rats

Highlights: • New chemical substance, “Ramalin”, derived from Antarctic lichen, acts as a powerful antioxidant and ROS scavenger. • Ramalin significantly reduces hepatic stellet cell activation, while also reducing malondialdehyde (MDA), and hydroxyproline (HP). • Ramalin offers hepatoprotection effect by ameliorating DMN-induced oxidative stress and hepatotoxicity. Hepatic fibrosis is characterized by the excessive accumulation of extracellular matrix (ECM), primarily collagen, within the liver. Because reactive oxygen species (ROS) has been implicated in its pathogenesis, the use of antioxidants as a potential treatment has been broadly explored. Here, we investigated the hepatoprotective properties of ramalin (RM), a compound extracted from the Antarctic lichen Ramalina terebrata, against hepatic fibrosis in vitro and in vivo. RM suppressed hepatic stellate cell (HSC) activation in vitro without any significant signs of adverse effects on the cells tested, and the accumulation of ECM was dramatically reduced in the liver tissue. Oral administration of RM in rats noticeably improved the gross appearance of the liver with increased body and liver weight relative to the DMN injected rats, and all of the serum biochemical markers returned to the normal range. RM treatment have ameliorated hepatic fibrosis in rats induced by DMN by repressing α-smooth muscle actin (α-SMA) and upregulating heme oxygenase-1 (HO-1). In addition, RM significantly reduced collagen accumulation, and levels of malondialdehyde (MDA) and hydroxyproline (HP) in the liver tissue of DMN injected rats. The efficacy exerted by RM was through erythroid 2–related factor 2 (Nrf2) mediated antioxidant response proteins such as HO-1 and NAD(P)H quinone dehydrogenase 1 (NQO-1). Our results show the beneficial effect of RM against the progression of hepatic fibrosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Modeling of inertial deposition in scaled models of rat and human nasal airways: Towards in vitro regional dosimetry in small animals

Rodents are routinely used in inhalation toxicology tests as human surrogates. However, in vitro dosimetry tests in rodent casts are still scarce due to small rodent airways and in vitro tests to quantify sub-regional dosimetry are still impractical. We hypothesized that for inertial particles whose deposition is dominated by airflow convection (Reynolds number) and particle inertia (Stokes number), the deposition should be similar among airway replicas of different scales if their Reynolds and Stokes numbers are kept the same. In this study, we aimed to (1) numerically test the hypothesis in three airway geometries: a USP induction port, a human nose model, and a Sprague-Dawley rat nose model, and (2) find the range of applicability of this hypothesis. Five variants of the USP and human nose models and three variants of the rat nose model were tested. Inhalation rates and particle sizes were scaled to match the Reynolds number and Stokes numbers. A low-Reynolds-number k–ω model was used to resolve the airflow and a Lagrangian tracking algorithm was used to simulate the particle transport and deposition. Statistical analysis of predicted doses was conducted using ANOVA. For normal inhalation rates and particle dia- meters ranging from 0.5 to 24 mm, the deposition differences between the life-size and scaled models are insignificant for all airway geometries considered (i.e., human nose, USP, and rat nose). Furthermore, the deposition patterns and exit particle profiles also look similar among scaled models. However, deposition rates and patterns start to deviate if inhalation rates are too low, or particle sizes are too large. For the rat nose, the threshold velocity was found to be 0.71 m/s and the threshold Froude number to be 50. Results of this study provide a theoretical foundation for sub-regional in vitro dosimetry tests in small animals and for interpretation of data from inter-species or intra-species with varying body sizes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

X-ray intravital microscopy for functional imaging in rat hearts using synchrotron radiation coronary microangiography

An X-ray intravital microscopy technique was developed to enable in vivo visualization of the coronary, cerebral, and pulmonary arteries in rats without exposure of organs and with spatial resolution in the micrometer range and temporal resolution in the millisecond range. We have refined the system continually in terms of the spatial resolution and exposure time. X-rays transmitted through an object are detected by an X-ray direct-conversion type detector, which incorporates an X-ray SATICON pickup tube. The spatial resolution has been improved to 6 {mu}m, yielding sharp images of small arteries. The exposure time has been shortened to around 2 ms using a new rotating-disk X-ray shutter, enabling imaging of beating rat hearts. Quantitative evaluations of the X-ray intravital microscopy technique were extracted from measurements of the smallest-detectable vessel size and detection of the vessel function. The smallest-diameter vessel viewed for measurements is determined primarily by the concentration of iodinated contrast material. The iodine concentration depends on the injection technique. We used ex vivo rat hearts under Langendorff perfusion for accurate evaluation. After the contrast agent is injected into the origin of the aorta in an isolated perfused rat heart, the contrast agent is delivered directly into the coronary arteries with minimum dilution. The vascular internal diameter response of coronary arterial circulation is analyzed to evaluate the vessel function. Small blood vessels of more than about 50 {mu}m diameters were visualized clearly at heart rates of around 300 beats/min. Vasodilation compared to the control was observed quantitatively using drug manipulation. Furthermore, the apparent increase in the number of small vessels with diameters of less than about 50 {mu}m was observed after the vasoactive agents increased the diameters of invisible small blood vessels to visible sizes. This technique is expected to offer the potential for direct investigation of mechanisms of vascular dysfunctions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

CarcSeq Measurement of Rat Mammary Cancer Driver Mutations and Relation to Spontaneous Mammary Neoplasia

Abstract The ability to deduce carcinogenic potential from subchronic, repeat dose rodent studies would constitute a major advance in chemical safety assessment and drug development. This study investigated an error-corrected NGS method (CarcSeq) for quantifying cancer driver mutations (CDMs) and deriving a metric of clonal expansion predictive of future neoplastic potential. CarcSeq was designed to interrogate subsets of amplicons encompassing hotspot CDMs applicable to a variety of cancers. Previously, normal human breast DNA was analyzed by CarcSeq and metrics based on mammary-specific CDMs were correlated with tissue donor age, a surrogate of breast cancer risk. Here we report development of parallel methodologies for rat. The utility of the rat CarcSeq method for predicting neoplastic potential was investigated by analyzing mammary tissue of 16-week-old untreated rats with known differences in spontaneous mammary neoplasia (Fischer 344, Wistar Han, and Sprague Dawley). Hundreds of mutants with mutant fractions ≥ 10−4 were quantified in each strain, most were recurrent mutations, and 42.5% of the nonsynonymous mutations have human homologs. Mutants in the mammary-specific target of the most tumor-sensitive strain (Sprague Dawley) showed the greatest nonsynonymous/synonymous mutation ratio, indicative of positive selection consistent with clonal expansion. For the mammary-specific target (Hras, Pik3ca, and Tp53 amplicons), median absolute deviation correlated with percentages of rats that develop spontaneous mammary neoplasia at 104 weeks (Pearson r = 1.0000, 1-tailed p = .0010). Therefore, this study produced evidence CarcSeq analysis of spontaneously occurring CDMs can be used to derive an early metric of clonal expansion relatable to long-term neoplastic outcome.

McKim, Karen L.↗
DOE OSTI2012

COMPARATIVE COMPUTATIONAL MODELING OF AIRFLOWS AND VAPOR DOSIMETY IN THE RESPIRATORY TRACTS OF RAT, MONKEY, AND HUMAN

Coupling computational fluid dynamics (CFD) with physiologically based pharmacokinetic (PBPK) models is useful for predicting site-specific dosimetry of airborne materials in the respiratory tract and elucidating the importance of species differences in anatomy, physiology, and breathing patterns. Historically, these models were limited to discrete regions of the respiratory system. CFD/PBPK models have now been developed for the rat, monkey, and human that encompass airways from the nose or mouth to the lung. A PBPK model previously developed to describe acrolein uptake in nasal tissues was adapted to the extended airway models as an example application. Model parameters for each anatomic region were obtained from the literature, measured directly, or estimated from published data. Airflow and site-specific acrolein uptake patterns were determined under steadystate inhalation conditions to provide direct comparisons with prior data and nasalonly simulations. Results confirmed that regional uptake was dependent upon airflow rates and acrolein concentrations with nasal extraction efficiencies predicted to be greatest in the rat, followed by the monkey, then the human. For human oral-breathing simulations, acrolein uptake rates in oropharyngeal and laryngeal tissues were comparable to nasal tissues following nasal breathing under the same exposure conditions. For both breathing modes, higher uptake rates were predicted for lower tracheo-bronchial tissues of humans than either the rat or monkey. These extended airway models provide a unique foundation for comparing dosimetry across a significantly more extensive range of conducting airways in the rat, monkey, and human than prior CFD models.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Anticonvulsant drug polytherapy stops status epilepticus and prevents neuronal loss in soman‐exposed rats

Introduction When treatment of status epilepticus (SE) is delayed, seizures become self‐sustaining and refractory to benzodiazepine therapy. Chemical warfare nerve agents (CWNAs), such as soman(GD), increase acetylcholine through inhibition of acetylcholine sterase and can lead to SE if seizures are not treated quickly and controlled. Prolonged seizures may lead to extensive neuropathology, spontaneous recurrent seizures and long‐term performance deficits. To identify a better treatment against pharmacoresistant seizures caused by GD exposure, we are using combinations of drugs aimed at reversing the effects of maladaptive receptor trafficking that follows CWNA exposure. Methods Rats were implanted with telemetry transmitters for continuous monitoring of EEG, body temperature and activity. After surgical recovery, rats were exposed to 1.2 LD 50 GD and treated 1 min later with atropine sulfate and the oxime HI‐6 and then 40 min after seizure onset with the anticonvulsant phenobarbital with or without the NMDA antagonist ketamine (PHE/KET), the benzodiazepine midazolam (PHE/MDZ) or a combination of all three drugs (PHE/KET/MDZ).Two weeks after exposure, rat brains were sectioned and stained for neuropathology assessments. Results Triple therapy with PHE/KET/MDZ reduced total time spent in seizures (SE +early recurrent seizures) in the first 72 h and reduced the number of spontaneous recurrent seizures compared to midazolam monotherapy. Tripletherapy also reduced the duration of toxic signs in the hours following GD‐exposure and prevented the development of hyperactivity that occurs in the weeks following exposure compared to GD/MDZ monotherapy. In addition, tripletherapy reduced loss of neurons in the piriform cortex and thalamus compared to GD/MDZ monotherapy. Conclusion Triple therapy with PHE/KET/MDZ hadanticonvulsant, antiepileptic, and neuroprotective effects compared with midazolammonotherapy in GD‐exposed rats. Triple therapy may be a highly effective approach against pharmacoresistant seizures, such as those caused by GD exposure, and may allow for administration of lower doses, resulting in fewer side effects than are often seen with large doses of individual drug therapies. Disclaimer: The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of the Army, Department of Defense, or the U.S. Government. The experimental protocol was approved by the Animal Care and Use Committee at the United States Army Medical Research Institute of Chemical Defense and all procedures were conducted in accordance with the principles stated in the Guide for the Care and Use of Laboratory Animals and the Animal Welfare Act of 1966 (P.L. 89‐544), as amended. Support or Funding Information KatieWalker, Erica Kundrick and Sean O'Brien were supported in part by an appointment to the Research Participation Program for the U.S. Army Medical Research and Materiel Command administered by the Oak Ridge Institute for Science and Education through an agreement between the U.S. Department of Energy and U.S. Army Medical Research and Materiel Command. This research was supported by the NIH U01 to Dr. Claude Wasterlain.

Stone, Michael↗
DOE OSTI2020

Muscone suppresses inflammatory responses and neuronal damage in a rat model of cervical spondylotic myelopathy by regulating Drp1‐dependent mitochondrial fission

Abstract Cervical spondylotic myelopathy (CSM) is a common cause of disability with few treatments. Aberrant mitochondrial dynamics play a crucial role in the pathogenesis of various neurodegenerative diseases. Thus, regulation of mitochondrial dynamics may offer therapeutic benefit for the treatment of CSM. Muscone, the active ingredient of an odoriferous animal product, exhibits anti‐inflammatory and neuroprotective effects for which the underlying mechanisms remain obscure. We hypothesized that muscone might ameliorate inflammatory responses and neuronal damage by regulating mitochondrial dynamics. To this end, the effects of muscone on a rat model of chronic cervical cord compression, as well as activated BV2 cells and injured neurons, were assessed. The results showed that muscone intervention improved motor function compared with vehicle‐treated rats. Indeed, muscone attenuated pro‐inflammatory cytokine expression, neuronal‐apoptosis indicators in the lesion area, and activation of the nod‐like receptor family pyrin domain‐containing 3 inflammasome, nuclear transcription factor‐κB, and dynamin‐related protein 1 in Iba1‐ and βIII‐tubulin‐labeled cells. Compared with vehicle‐treated rats, compression sites of muscone‐treated animals exhibited elongated mitochondrial morphologies in individual cell types and reduced reactive oxygen species. In vitro results indicated that muscone suppressed microglial activation and neuronal damage by regulating related‐inflammatory or apoptotic molecules. Moreover, muscone inhibited dynamin‐related protein 1 activation in activated BV2 cells and injured neurons, whereby it rescued mitochondrial fragmentation and reactive oxygen species production, which regulate a wide range of inflammatory and apoptotic molecules. Our findings reveal that muscone attenuates neuroinflammation and neuronal damage in rats with chronic cervical cord compression by regulating mitochondrial fission events, suggesting its promise for CSM therapy. image

Zhou, Long‐yun↗