Intestinal epithelia are critical for maintaining gastrointestinal homeostasis. Epithelial barrier injury, causing inflammation and vascular damage, results in inflammatory hypoxia, and thus, healing ...occurs in an oxygen-restricted environment. The transcription factor hypoxia-inducible factor (HIF)-1 regulates genes important for cell survival and repair, including the cell adhesion protein β1-integrin. Integrins function as αβ-dimers, and α-integrin-matrix binding is critical for cell migration. We hypothesized that HIF-1 stabilization accelerates epithelial migration through integrin-dependent pathways. We aimed to examine functional and posttranslational activity of α-integrins during HIF-1-mediated intestinal epithelial healing. Wound healing was assessed in T84 monolayers over 24 h with/without prolyl-hydroxylase inhibitor (PHDi) (GB-004), which stabilizes HIF-1. Gene and protein expression were measured by RT-PCR and immunoblot, and α-integrin localization was assessed by immunofluorescence. α-integrin function was assessed by antibody-mediated blockade, and integrin α6 regulation was determined by HIF-1α chromatin immunoprecipitation. Models of mucosal wounding and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were used to examine integrin expression and localization in vivo. PHDi treatment accelerated wound closure and migration within 12 h, associated with increased integrin α2 and α6 protein, but not α3. Functional blockade of integrins α2 and α6 inhibited PHDi-mediated accelerated wound closure. HIF-1 bound directly to the integrin α6 promoter. PHDi treatment accelerated mucosal healing, which was associated with increased α6 immunohistochemical staining in wound-associated epithelium and wound-adjacent tissue. PHDi treatment increased α6 protein levels in colonocytes of TNBS mice and induced α6 staining in regenerating crypts and reepithelialized inflammatory lesions. Together, these data demonstrate a role for HIF-1 in regulating both integrin α2 and α6 responses during intestinal epithelial healing.
HIF-1 plays an important role in epithelial restitution, selectively inducing integrins α6 and α2 to promote migration and proliferation, respectively. HIF-stabilizing prolyl-hydroxylase inhibitors accelerate intestinal mucosal healing by inducing epithelial integrin expression.
Male Fischer-344 rats were exposed by inhalation to 1200 ppm toluene (14 hr/day, 7 days/week for 5 weeks) beginning just after weaning or as young adults. During the fifth week of exposure, they were ...trained to perform a multisensory conditioned pole-climb avoidance response (CAR) task using a 4-kHz tone, a change in the intensity of the test chamber light, or a nonaversive current on the grill floor as the stimuli. When tested the week after the exposures ended, both groups of toluene-exposed rats were deficient in their performance of the CAR to a 20-kHz tone. This effect was significantly greater for the rats exposed beginning just after weaning than it was for the young adult rats. Subsequent behavioral and electrophysiologic audiometry confirmed the presence of a toluene-induced high-frequency hearing loss in both groups of rats with the more severe deficits occurring in the younger rats. Preliminary morphologic examinations revealed loss of, and/or damage to, hair cells in the basal turn of the cochlea of the younger toluene-exposed rats. These results confirm our earlier discovery that inhalation exposure to toluene causes hearing deficits in rats, and they indicate that young, prepubertal rats are more severely affected than older rats.
Technological advances in imaging and data acquisition are leading to the development of petabyte-scale neuroscience image datasets. These large-scale volumetric datasets pose unique challenges since ...analyses often span the entire volume, requiring a unified platform to access it. In this paper, we describe the Brain Observatory Storage Service and Database (BossDB), a cloud-based solution for storing and accessing petascale image datasets. BossDB provides support for data ingest, storage, visualization, and sharing through a RESTful Application Programming Interface (API). A key feature is the scalable indexing of spatial data and automatic and manual annotations to facilitate data discovery. Our project is open source and can be easily and cost effectively used for a variety of modalities and applications, and has effectively worked with datasets over a petabyte in size.
Embryo culture and assisted reproductive technologies have been associated with a disproportionately high number of epigenetic abnormalities in the resulting offspring. However, the mechanisms by ...which these techniques influence the epigenome remain poorly defined. In this study, we evaluated the capacity of oxygen concentration to influence the transcriptional control of a selection of key enzymes regulating chromatin structure. In mouse embryonic stem cells, oxygen concentrations modulated the transcriptional regulation of the TET family of enzymes, as well as the de novo methyltransferase Dnmt3a. These transcriptional changes were associated with alterations in the control of multiple imprinted genes, including H19, Igf2, Igf2r, and Peg3. Similarly, exposure of in vitro produced bovine embryos to atmospheric oxygen concentrations was associated with disruptions in the transcriptional regulation of TET1, TET3, and DNMT3a, along with the DNA methyltransferase co-factor HELLS. In addition, exposure to high oxygen was associated with alterations in the abundance of transcripts encoding members of the Polycomb repressor complex (EED and EZH2), the histone methyltransferase SETDB1 and multiple histone demethylases (KDM1A, KDM4B, and KDM4C). These disruptions were accompanied by a reduction in embryo viability and suppression of the pluripotency genes NANOG and SOX2. These experiments demonstrate that oxygen has the capacity to modulate the transcriptional control of chromatin modifying genes involved in the establishment and maintenance of both pluripotency and genomic imprinting.
Sampling distortion product otoacoustic emissions (DPOAEs) at multiple f
2
/f
1
ratios and f
2
frequency values produces a DPOAE "map." This study examined the efficacy of DPOAE mapping compared with ...pure tone audiometry and standard DPOAEs for detecting noise effects in subjects exposed to loud sound.
A map significance score was developed as a single measure of map change. Significance scores were evaluated before and after exposure to: loud music (LM), controlled noise (CN), and firing range noise (FR) in three separate sets of subjects. Scores were compared to audiometry and standard DPOAE results in the LM study.
The LM and CN exposure studies involved 22, and 20 healthy young subjects respectively with normal hearing. Eight Marines were studied before and after FR exposure.
After LM exposure, audiometry showed significant changes at 1, 2, 4, and 6 kHz. Standard DPOAE measures were also significantly different at several frequencies. Map significance scores detected changes more effectively and showed the distribution of DPOAE alterations.
Map significance scores detected changes after noise exposure more reliably than audiometry and standard DPOAEs. Additionally, maps showed a diffuse response to sound exposure perhaps explaining why individual DP-grams appear less sensitive.
•Modeling of different initial spatial profile and velocity distribution shows how physical processes affect exospheric distribution.•We have detailed that the inventory from infalling ...micrometeoroids is not the prime contributor to H2 in the lunar exosphere.•The solar wind is a sufficient source of hydrogen that can supply the observed H2 exosphere by chemical sputtering of implant solar wind H.•To produce H2 density of 1200cm−3, 10% of the solar wind would need to be converted to H2.
We investigate the density and spatial distribution of the H2 exosphere of the Moon assuming various source mechanisms. Owing to its low mass, escape is non-negligible for H2. For high-energy source mechanisms, a high percentage of the released molecules escape lunar gravity. Thus, the H2 spatial distribution for high-energy release processes reflects the spatial distribution of the source. For low energy release mechanisms, the escape rate decreases and the H2 redistributes itself predominantly to reflect a thermally accommodated exosphere. However, a small dependence on the spatial distribution of the source is superimposed on the thermally accommodated distribution in model simulations, where density is locally enhanced near regions of higher source rate. For an exosphere accommodated to the local surface temperature, a source rate of 2.2gs−1 is required to produce a steady state density at high latitude of 1200cm−3. Greater source rates are required to produce the same density for more energetic release mechanisms. Physical sputtering by solar wind and direct delivery of H2 through micrometeoroid bombardment can be ruled out as mechanisms for producing and liberating H2 into the lunar exosphere. Chemical sputtering by the solar wind is the most plausible as a source mechanism and would require 10–50% of the solar wind H+ inventory to be converted to H2 to account for the observations.
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