Examining the Effects of 4He Exposure on the Gut-Brain Axis

Beyond low-Earth orbit, space radiation poses significant risks to astronaut health. Previous studies have shown that the microbial composition of the gastrointestinal (GI) microbiome changes upon exposure to high-linear energy transfer radiation. Interestingly, radiation-induced shifts in GI microbiota composition are linked to various neuropsychological disorders. Herein, we aimed to study changes in GI microbiota and behaviors of rats exposed to whole-body radiation (0, 5 or 25 cGy 4He, 250 MeV/n) at approximately 6 months of age. Fecal samples were collected 24 h prior to 4He irradiation and 24 h and 7 days postirradiation for quantitative PCR analyses to assess fecal levels of spore-forming bacteria (SFB), Bifidobacterium, Lactobacillus and Akkermansia. Rats were also tested in the social odor recognition memory (SORM) test at day 7 after 4He exposure. A subset of rats was euthanized 90 min after completion of the SORM test, and GI tissue from small intestine to colon were prepared for examining overall histological changes and immunohistochemical staining for serotonin (5-HT). No notable pathological changes were observed in GI tissues. Akkermansia spp. and SFB were significantly decreased in the 25 cGy group at 24 h and 7 days postirradiation compared to pre-exposure, respectively. Bifidobacterium and Lactobacillus spp. showed no significant changes. 5-HT production was significantly higher in the proximal small intestine and the cecum in the 25 cGy group compared to the sham group. The 25 cGy group exhibited deficits in recognition in SORM testing at day 7 postirradiation. Taken together, these results suggest a connection between GI microbiome composition, serotonin production, and neurobehavioral performance, and that this connection may be disrupted upon exposure to 25 cGy of 4He ions.

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Splanchnic tissues undergo hypoxic stress during whole body hyperthermia

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1999.276.5.g1195 ◽

1999 ◽

Vol 276 (5) ◽

pp. G1195-G1203 ◽

Cited By ~ 34

Author(s):

David M. Hall ◽

Kirk R. Baumgardner ◽

Terry D. Oberley ◽

Carl V. Gisolfi

Keyword(s):

Small Intestine ◽

Heat Stress ◽

Heat Exposure ◽

Metabolic Stress ◽

Liver Glycogen ◽

Whole Body ◽

Hypoxic Cell ◽

Hypoxic Stress ◽

Proximal Small Intestine ◽

Radical Content

Exposure of conscious animals to environmental heat stress increases portal venous radical content. The nature of the observed heat stress-inducible radical molecules suggests that hyperthermia produces cellular hypoxic stress in liver and intestine. To investigate this hypothesis, conscious rats bearing in-dwelling portal venous and femoral artery catheters were exposed to normothermic or hyperthermic conditions. Blood gas levels were monitored during heat stress and for 24 h following heat exposure. Hyperthermia significantly increased arterial O2saturation, splanchnic arterial-venous O2difference, and venous[Formula: see text], while decreasing venous O2saturation and venous pH. One hour after heat exposure, liver glycogen levels were decreased ∼20%. Two hours after heat exposure, the splanchnic arterial-venous O2difference remained elevated in heat-stressed animals despite normal Tc. A second group of rats was exposed to similar conditions while receiving intra-arterial injections of the hypoxic cell marker [3H]misonidazole. Liver and intestine were biopsied, and [3H]misonidazole content was quantified. Heat stress increased tissue [3H]misonidazole retention 80% in the liver and 29% in the small intestine. Cellular [3H]misonidazole levels were significantly elevated in intestinal epithelial cells and liver zone 2 and 3 hepatocytes and Kupffer cells. This effect was most prominent in the proximal small intestine and small liver lobi. These data provide evidence that hyperthermia produces cellular hypoxia and metabolic stress in splanchnic tissues and suggest that cellular metabolic stress may contribute to radical generation during heat stress.

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Endogenous Small Intestinal Microbiome Determinants of Transient Colonization Efficiency by Bacteria from Fermented Dairy Products; A Randomized Controlled Trial

10.21203/rs.3.rs-1196536/v1 ◽

2021 ◽

Author(s):

Edoardo Zaccaria ◽

Tim Klaassen ◽

Annick M.E. Alleleyn ◽

Jos Boekhorst ◽

Tamara Smokvina ◽

...

Keyword(s):

Small Intestine ◽

Energy Metabolism ◽

Intestinal Microbiota ◽

Lactobacillus Delbrueckii ◽

Intestinal Microbiome ◽

Microbial Composition ◽

Microbiome Composition ◽

Mucosal Barrier Function ◽

Small Intestinal ◽

Intestine Microbiome

Abstract BackgroundThe effects of fermented food consumption on the small intestine microbiome and its role on host homeostasis are largely uncharacterized as our knowledge on intestinal microbiota relies mainly on faecal samples analysis. We investigated changes in the small intestinal microbial composition and functionality, short chain fatty acid (SCFA) profiles, and on the gastro-intestinal (GI) permeability in ileostomy subjects upon the consumption of fermented milk products.ResultsWe report the results from a randomized, cross-over, explorative study where 16ileostomy subjects underwent 3, 2-week interventions periodsin which they daily consumed either milk fermented by Lacticaseibacillus rhamnosus CNCM I-3690, or milk fermented by Streptococcus thermophilus CNCM I-1630 and Lactobacillus delbrueckii subsp. bulgaricus CNCM I-1519, or a chemically acidified milk (placebo). Weperformed metataxonomic, metatranscriptomic analysis and SCFA profiling of ileostomy effluents as well as a sugar permeability test andto investigate the microbiome impact of these interventions and their potential effect on mucosal barrier function. Consumption of the intervention products significantly impacted the small intestinal microbiome composition and functionality but did not affect the SCFA levels in ileostoma effluent, or the gastro-intestinal permeability. Theimpact on microbiome composition was highly personalized,andwe identified the poorly characterized bacterial family, Peptostreptococcaceae, to be positively associated with low abundance of the ingested bacteria. Activity profiling of the microbiota revealed that carbon- versus amino acid-derived energy metabolism of the endogenous microbiome could be responsible for the individual-specific intervention effects on the small intestine microbiome composition and function.ConclusionsThe ingested bacteria are the main drivers of the intervention effect on the small intestinal microbiota composition. Their transient abundance level is highly personalized and influenced by the energy metabolism of the ecosystem that is reflected by its microbial composition (http://www.clinicaltrials.gov, ID NCT NCT02920294).

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The Patterns of Simultaneous Intraluminal Pressure Changes in the Human Proximal Small Intestine

Gastroenterology ◽

10.1016/s0016-5085(19)34739-0 ◽

1964 ◽

Vol 47 (3) ◽

pp. 258-268 ◽

Cited By ~ 16

Author(s):

Gerald Friedman ◽

Jerome D. Waye ◽

Leonard A. Weingarten ◽

Henry D. Janowitz

Keyword(s):

Small Intestine ◽

Intraluminal Pressure ◽

Proximal Small Intestine ◽

Pressure Changes

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Electromagnetic-launch-based method for cost-efficient space debris removal

Open Astronomy ◽

10.1515/astro-2020-0016 ◽

2020 ◽

Vol 29 (1) ◽

pp. 94-106

Author(s):

Chongyuan Hou ◽

Yuan Yang ◽

Yikang Yang ◽

Kaizhong Yang ◽

Xiao Zhang ◽

...

Keyword(s):

Space Debris ◽

Orbit Space ◽

Low Earth Orbit ◽

Research Progress ◽

Area Of Interest ◽

Electromagnetic Launch ◽

Debris Removal ◽

Significant Research ◽

Electromagnetic Launcher ◽

Cost Efficient

AbstractThe increase in space debris orbiting Earth is a critical problem for future space missions. Space debris removal has thus become an area of interest, and significant research progress is being made in this field. However, the exorbitant cost of space debris removal missions is a major concern for commercial space companies. We therefore propose the debris removal using electromagnetic launcher (DREL) system, a ground-based electromagnetic launch system (railgun), for space debris removal missions. The DREL system has three components: a ground-based electromagnetic launcher (GEML), suborbital vehicle (SOV), and mass of micrometer-scale dust (MSD) particles. The average cost of removing a piece of low-earth orbit space debris using DREL was found to be approximately USD 160,000. The DREL method is thus shown to be economical; the total cost to remove more than 2,000 pieces of debris in a cluster was only approximately USD 400 million, compared to the millions of dollars required to remove just one or two pieces of debris using a conventional space debris removal mission. By using DREL, the cost of entering space is negligible, thereby enabling countries to remove their space debris in an affordable manner.

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Measurement of protein turnover in the small intestine of lambs. 2. Effects of feed intake

The Journal of Agricultural Science ◽

10.1017/s0021859696004091 ◽

1997 ◽

Vol 128 (2) ◽

pp. 233-246 ◽

Cited By ~ 6

Author(s):

S. A. NEUTZE ◽

J. M. GOODEN ◽

V. H. ODDY

Keyword(s):

Amino Acids ◽

Protein Synthesis ◽

Small Intestine ◽

Experimental Model ◽

Feed Intake ◽

Protein Turnover ◽

Jugular Vein ◽

Specific Radioactivity ◽

Whole Body ◽

Body Protein

This study used an experimental model, described in a companion paper, to examine the effects of feed intake on protein turnover in the small intestine of lambs. Ten male castrate lambs (∼ 10 months old) were offered, via continuous feeders, either 400 (n = 5) or 1200 (n = 5) g/day lucerne chaff, and mean experimental liveweights were 28 and 33 kg respectively. All lambs were prepared with catheters in the cranial mesenteric vein (CMV), femoral artery (FA), jugular vein and abomasum, and a blood flow probe around the CMV. Cr-EDTA (0·139 mg Cr/ml, ∼ 0·2 ml/min) was infused abomasally for 24 h and L-[2,6-3H]phenylalanine (Phe) (420±9·35 μCi into the abomasum) and L-[U-14C]phenylalanine (49·6±3·59 μCi into the jugular vein) were also infused during the last 8 h. Blood from the CMV and FA was sampled during the isotope infusions. At the end of infusions, lambs were killed and tissue (n = 4) and digesta (n = 2) samples removed from the small intestine (SI) of each animal. Transfers of labelled and unlabelled Phe were measured between SI tissue, its lumen and blood, enabling both fractional and absolute rates of protein synthesis and gain to be estimated.Total SI mass increased significantly with feed intake (P < 0·05), although not on a liveweight basis. Fractional rates of protein gain in the SI tended to increase (P = 0·12) with feed intake; these rates were −16·2 (±13·7) and 23·3 (±15·2) % per day in lambs offered 400 and 1200 g/day respectively. Mean protein synthesis and fractional synthesis rates (FSR), calculated from the mean retention of 14C and 3H in SI tissue, were both positively affected by feed intake (0·01 < P < 0·05). The choice of free Phe pool for estimating precursor specific radioactivity (SRA) for protein synthesis had a major effect on FSR. Assuming that tissue free Phe SRA represented precursor SRA, mean FSR were 81 (±15) and 145 (±24) % per day in lambs offered 400 and 1200 g/day respectively. Corresponding estimates for free Phe SRA in the FA and CMV were 28 (±2·9) and 42 (±3·5) % per day on 400 g/day, and 61 (±2·9) and 94 (±6·0) on 1200 g/day. The correct value for protein synthesis was therefore in doubt, although indirect evidence suggested that blood SRA (either FA or CMV) may be closest to true precursor SRA. This evidence included (i) comparison with flooding dose estimates of FSR, (ii) comparison of 3H[ratio ]14C Phe SRA in free Phe pools with this ratio in SI protein, and (iii) the proportion of SI energy use associated with protein synthesis.Using the experimental model, the proportion of small intestinal protein synthesis exported was estimated as 0·13–0·27 (depending on the choice of precursor) and was unaffected by feed intake. The contribution of the small intestine to whole body protein synthesis tended to be higher in lambs offered 1200 g/day (0·21) than in those offered 400 g/day (0·13). The data obtained in this study suggested a role for the small intestine in modulating amino acid supply with changes in feed intake. At high intake (1200 g/day), the small intestine increases in mass and CMV uptake of amino acids is less than absorption from the lumen, while at low intake (400 g/day), this organ loses mass and CMV uptake of amino acids exceeds that absorbed. The implications of these findings are discussed.

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Atomic Oxygen Resistant Polysiloxane Coatings for Low Earth Orbit Space Structures

Materials Science Forum ◽

10.4028/www.scientific.net/msf.830-831.699 ◽

2015 ◽

Vol 830-831 ◽

pp. 699-702 ◽

Cited By ~ 5

Author(s):

G.N. Arjun ◽

T.L. Lincy ◽

T.S. Sajitha ◽

S. Bhuvaneshwari ◽

Thomas Deepthi ◽

...

Keyword(s):

Reaction Time ◽

Surface Morphology ◽

Mass Loss ◽

Atomic Oxygen ◽

Thermo Gravimetric Analysis ◽

Orbit Space ◽

Solid Content ◽

Low Earth Orbit ◽

Gravimetric Analysis ◽

Coating Materials

Polysiloxane resin copolymer was synthesized through acid catalyzed hydrolysis of methyl triethoxysilane (MTEOS) and diethoxytetramethyldisiloxane (DEOTMDS). The effect of reaction time on the properties of the polymer was studied and this copolymer was characterized by GPC, 29Si NMR, IR, TGA, viscosity, refractive index, specific gravity and solid content. 29Si NMR and IR showed characteristic signals of Si-O-Si linkage which confirmed the formation of the polymer. GPC and solid content analysis showed an increasing trend in molecular weight with reaction time. Thermo gravimetric analysis showed that the polymer was thermally stable upto ≈ 260°C and all the polymers gave a ceramic residue in the range of 77-80% at 900°C. Siloxane prepared inhouse and methyl phenyl silsequioxane (control) were used as coating materials and atomic oxygen (AO) resistance was evaluated on Al-Kapton, carbon polyimide composite and glass polyimide composite. The mass loss and surface morphology of the coated samples were measured at different time intervals. It is observed that mass loss of polysiloxane coated samples was very less, compared to coated control samples. The morphology of all the samples were studied using FESEM. Erosion kinetics and surface morphology investigation indicate that the polysiloxane coating possesses excellent AO resistance, and displays better cracking resistance on AO exposure.

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Absorption and metabolism of glucose by the mesenteric-drained viscera of sheep fed on dried-grass or ground, maize-based diets

British Journal Of Nutrition ◽

10.1079/bjn19850130 ◽

1985 ◽

Vol 54 (2) ◽

pp. 449-458 ◽

Cited By ~ 31

Author(s):

A. N. Janes ◽

T. E. C. Weekes ◽

D. G. Armstrong

Keyword(s):

Small Intestine ◽

Turnover Rate ◽

Glucose Utilization ◽

Venous Blood ◽

Glucose Production ◽

Glucose Absorption ◽

Endogenous Glucose Production ◽

Whole Body ◽

Glucose Turnover ◽

Total Glucose

1. Sheep fitted with re-entrant canulas in the proximal duodenum and terminal ileum were used to determine the amount of α-glucoside entering, and apparently disappearing from, the small intestine when either dried-grass or ground maize-based diets were fed. The fate of any α-glucoside entering the small intestine was studied by comparing the net disappearance of such a-glucoside from the small intestine with the absorption of glucose into the mesenteric venous blood.2. Glucose absorption from the small intestine was measured in sheep equipped with catheters in the mesenteric vein and carotid artery. A continuous infusion of [6-3H]glucose was used to determine glucose utilization by the mesenteric-drained viscera and the whole-body glucose turnover rate (GTR).3. The amounts of α-glucoside entering the small intestine when the dried-grass and maize-based diets were given were 13.9 (SE 1.5) and 95.4 (SE 16.2) g/24 h respectively; apparent digestibilities of such α-glucoside in the small intestine were 60 and 90% respectively.4. The net absorption of glucose into the mesenteric venous blood was —2.03 (SE 1.20) and 19.28 (SE 0.75) mmol/h for the dried-grass and maize-based diets respectively. Similarly, total glucose absorption amounted to 1.52 (SE 1.35) and 23.33 (SE 1.86) mmol/h (equivalent to 7 and 101 g/24 h respectively). These values represented 83 and 11 1% of the a-glucoside apparently disappearing from the small intestine, determined using the re-entrant cannulated sheep.5. Total glucose absorption represented 8 and 61% of the whole-body GTR for the dried-grass and maize-based diets respectively. Endogenous glucose production was significantly lower when the sheep were fed on the maize-based diet compared with the dried-grass diet.6. The mesenteric-drained viscera metabolized a small amount of glucose, equivalent to 234 and 17% of the total glucose absorbed for the dried-grass and maize-based diets respectively.7. It is concluded that a large proportion of the starch entering the small intestine of sheep given a maize-based diet is digested and absorbed as glucose, and thus contributes to the whole-body GTR.

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