SEARCH · Engineering Papers

Results for “lipopolysaccharide”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

86 records · Page 5

All sources NASA NTRS DOE OSTI

NASA NTRS2002

Microarray analysis identifies Salmonella genes belonging to the low-shear modeled microgravity regulon

The low-shear environment of optimized rotation suspension culture allows both eukaryotic and prokaryotic cells to assume physiologically relevant phenotypes that have led to significant advances in fundamental investigations of medical and biological importance. This culture environment has also been used to model microgravity for ground-based studies regarding the impact of space flight on eukaryotic and prokaryotic physiology. We have previously demonstrated that low-shear modeled microgravity (LSMMG) under optimized rotation suspension culture is a novel environmental signal that regulates the virulence, stress resistance, and protein expression levels of Salmonella enterica serovar Typhimurium. However, the mechanisms used by the cells of any species, including Salmonella, to sense and respond to LSMMG and identities of the genes involved are unknown. In this study, we used DNA microarrays to elucidate the global transcriptional response of Salmonella to LSMMG. When compared with identical growth conditions under normal gravity (1 x g), LSMMG differentially regulated the expression of 163 genes distributed throughout the chromosome, representing functionally diverse groups including transcriptional regulators, virulence factors, lipopolysaccharide biosynthetic enzymes, iron-utilization enzymes, and proteins of unknown function. Many of the LSMMG-regulated genes were organized in clusters or operons. The microarray results were further validated by RT-PCR and phenotypic analyses, and they indicate that the ferric uptake regulator is involved in the LSMMG response. The results provide important insight about the Salmonella LSMMG response and could provide clues for the functioning of known Salmonella virulence systems or the identification of uncharacterized bacterial virulence strategies.

Non-NASA Center↗

NASA NTRS2001

Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

NASA Discipline Radiation Health↗

NASA NTRS1984

Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Ribitol/analogs & derivatives↗

NASA NTRS1999

Immunocytochemical localization of latent transforming growth factor-beta1 activation by stimulated macrophages

Transforming growth factor-beta1 (TGF-beta) is secreted in a latent form consisting of mature TGF-beta noncovalently associated with its amino-terminal propeptide, which is called latency associated peptide (LAP). Biological activity depends upon the release of TGF-beta from the latent complex following extracellular activation, which appears to be the key regulatory mechanism controlling TGF-beta action. We have identified two events associated with latent TGF-beta (LTGF-beta) activation in vivo: increased immunoreactivity of certain antibodies that specifically detect TGF-beta concomitant with decreased immunoreactivity of antibodies to LAP. Macrophages stimulated in vitro with interferon-gamma and lipopolysaccharide reportedly activate LTGF-beta via cell membrane-bound protease activity. We show through dual immunostaining of paraformaldehyde-fixed macrophages that such physiological TGF-beta activation is accompanied by a loss of LAP immunoreactivity with concomitant revelation of TGF-beta epitopes. The induction of TGF-beta immunoreactivity colocalized with immunoreactive betaglycan/RIII in activated macrophages, suggesting that LTGF-beta activation occurs on the cell surface. Confocal microscopy of metabolically active macrophages incubated with antibodies to TGF-beta and betaglycan/RIII prior to fixation supported the localization of activation to the cell surface. The ability to specifically detect and localize LTGF-beta activation provides an important tool for studies of its regulation.

NASA Discipline Radiation Health↗

NASA NTRS1998

Effects of 2-deoxy-D-glucose administration on immune parameters in mice

Physical exercise and diet alterations have been shown to affect immune parameters. Similar effects are also induced by the administration of the non-metabolizable glucose analog, 2-deoxy-D-glucose (2-DG). The current study was designed to characterize the effects of glucoprivation induced by 2-DG administration on leukocyte subset distribution and function. BDF1 mice (n = 8 per group) were injected intraperitoneally one or three times with 0, 500, 750, 1000 or 1500 mg/kg of 2-DG. Two hours after the last injection of 2-DG, immunological parameters were analyzed. A dose-dependent increase in plasma glucose concentrations of mice injected once with up to 1500 mg/kg of 2-DG was observed (p < 0.001). After either one or three injections of up to 1500 mg/kg of 2-DG, corticosterone levels, leukocyte counts in the spleen, and CD3+ cells in the thymus increased. In vitro proliferation of partially purified lymphocytes from the spleen in the presence of both concanavalin-A and lipopolysaccharide decreased in a dose dependent manner (p < 0.05). In addition, after three injections, the proportion of both thymocytes and splenocytes bearing alphabeta-TCR increased as the concentration of 2-DG increased (p < 0.01). These results demonstrate that 2-DG administration induced dose-dependent changes in both thymus and spleen cell distribution and function.

NASA Discipline Regulatory Physiology↗

NASA NTRS1998

Salmonella infections in the absence of the major histocompatibility complex II

We examined the pathogenesis of the facultative intracellular bacterium, Salmonella typhimurium in MHCII-/-, C2D knock-out mice, and wild-type C57BL/6J mice. The MHCII knock-out shortened the kinetics of animal death and reduced the dose of S. typhimurium needed to kill mice. We measured the physiological and cytokine responses of both mouse strains after S. typhimurium injection. Animal weight loss, spleen weights, liver weights, thymus weights, and serum corticosterone concentrations were comparable after injection with several doses of bacteria. The only physiological differences observed between the two strains were observed 3 days after injection of the highest dose of bacteria tested. Serum concentrations of tumor necrosis factor alpha, interleukin-2, and interleukin-6 increased in a dose-dependent fashion irrespective of mouse MHCII expression. Therefore, even in the absence of MHCII, mice are able to mount relatively normal physiological and immunological responses. Consistent with these normal responses, an increased percentage of MHCII-/- mice, primed with a low dose of bacteria 13 days earlier, were able to survive a lethal challenge of Salmonella compared with unprimed controls. Lastly, C2D mice had significantly higher serum interleukin-10 concentrations than C57BL/6J mice 48 h after infection with all doses of S. typhimurium. C2D macrophages also secreted significantly more IL-10 and less NO and O2- after lipopolysaccharide or phorbol ester stimulation in vitro than wild-type macrophages.

Non-NASA Center↗

NASA NTRS1992

Potentiation of lymphocyte proliferative responses by nickel sulfide

Crystalline nickel sulfide (NiS) induced a spleen cell proliferation that resembles a mixed lymphocyte reaction (MLR). It depended on cell-cell interaction, induced high levels of interleukin-1 (IL-1) and interleukin-2 (IL-2) and the responding cell subpopulation was composed of CD4+ T lymphocytes. Furthermore, the proliferation was inhibited in a dose-dependent manner by magnesium. Crystalline NiS also increased significantly the spleen cell proliferative response to concanavalin A (Con A) and lipopolysaccharide (LPS) with magnesium potentiating the combined effects of crystalline NiS and mitogens. Interestingly, crystalline NiS did not show any effect on the induction of IL-2 by Con A. The results described herein suggest that crystalline NiS can potentiate both antigenic (MLR) and mitogenic (Con A and LPS) proliferative responses in vitro. Crystalline NiS appears to potentiate these responses by acting in the form of ionic nickel on several intracellular targets for which magnesium ions have different noncompetitive interactions. The effects of magnesium on the potentiating action of crystalline NiS are different depending upon the type of primary stimulatory signal for proliferation (mitogenic or antigenic).

NASA Discipline Cell Biology↗

NASA NTRS2006

In vitro Catecholamine Exposure Produces Variable Effects on the B7 Costimulatory Pathway in Human Monocytic Cells

Catecholamines have been associated with immunomodulation of the adaptive immune system towards a Th2 response in vitro. We therefore examined the role of in vitro epinephrine (EPI) and norepinephrine (NE) exposure on the B7 costimulatory expression of antigen presenting cells (APC) from human monocytic cell lines and human peripheral blood mononuclear cells (PBMC). THP1 monocytic cells and CD14+ cells from normal human PBMC were stimulated with lipopolysaccharide (LPS) and incubated with physiologic stress levels (10(exp -6) - 10(exp -8)M) of EPI or NE for 24 hours. Cells were subsequently stained with CD80 FITC, CD86 PE, and CD14 PC5 antibodies and analyzed by flow cytometry for changes in fluorescence and mean fluorescence intensity (MFI). Exposure of THP1 to EPI in vitro at concentrations of 10(exp -6), 10(exp -7) and 10(exp -8)M significantly decreased mean CD80 from 42 plus or minus 0.7% to 11 plus or minus 0.44%, 19.1 plus or minus 2.0%, and 30.7 plus or minus 2.1% expression, respectively (p less than 0.01). In addition, CD86 expression increased with EPI at 10(exp -6), 10(exp -7) and 10(exp -8) M from 9.2 plus or minus 0.52% to 41 plus or minus 3.8%, 26.4 plus or minus 1.9%, and 15.74 plus or minus 1.8% expression, respectively (p less than 0.01). Similar results for mean CD80 and CD86 percent expression were observed for CD14+ cells from PBMC with a sample size of N = 6 and for NE when substituted for EPI. The data show that in vitro exposure to catecholamines significantly decreases %CD86 expression and significantly increases %CD86 expression in THP1 cells and human CD14+ APC. Previous studies have suggested an association between increased CD86 expression and TH2 activity. Thus, these data suggest that immunomodulation by catecholamines results in part by the variable effects of the B7 costimulatory pathway in APC.

Salicru, A. N.↗

NASA NTRS2010

Enhanced Microbial Detection Capabilities by a Rapid Portable Instrument

We present data describing a progression of continuing technology development - from expanding the detection capabilities of the current PTS unit to re-outfitting the instrument with a protein microarray increasing the number of detectable compounds. To illustrate the adaptability of the cartridge format, on-orbit operations data from the ISS demonstrate the detection of the fungal cell wall compound beta-glucan using applicable LOCAD-PTS cartridges. LOCAD-PTS is a handheld device consisting of a spectrophotometer, an onboard pumping mechanism, and data storage capabilities. A suite of interchangeable cartridges lined with four distinct capillaries allow a hydrated sample to mix with necessary reagents in the channels before being pumped to the optical well for spectrophotometric analysis. The reagents housed in one type of cartridge trigger a reaction based on the Limulus Amebocyte Lysate (LAL) assay, which results in the release of paranitroaniline dye. The dye is measured using a 395 nm filter. The LAL assay detects the Gram-negative bacterial cell wall molecule, endotoxin or lipopolysaccharide (LPS). The more dye released, the greater the concentration of endotoxin in the sample. Sampling, quantitative analysis, and data retrieval require less than 20 minutes. This is significantly faster than standard culture-based methods, which require at least a 24 hour incubation period.Using modified cartridges, we demonstrate the detection of Gram negative bacteria with protein microarray technology. Additionally, we provide data from multiple field tests where both standard and advanced PTS technologies were used. These tests investigate the transfer of target microbial molecules from one surface to another. Collectively, these data demonstrate that the new cartridges expand the number of compounds detected by LOCAD-PTS, while maintaining the rapid, in situ analysis characteristic of the instrument. The unit provides relevant data for verifying sterile sample collection protocols, which are critical for conducting accurate scientific experiments during future missions to the Moon and Mars.

Morris, Heather↗

NASA NTRS2001

Altered TNF-Alpha, Glucose, Insulin and Amino Acids in Islets Langerhans Cultured in a Microgravity Model System

The present studies were designed to determine effects of a microgravity model system upon lipopolysaccharide (LPS) stimulated tumor necrosis factor alpha (TNF-alpha) activity and indices of insulin and fuel homeostasis of pancreatic islets of Langerhans. Islets (1726+/-1 17,150 u IEU) from Wistar Furth rats were treated as: 1) HARV (High Aspect Ratio Vessel cell culture) , 2) HARV plus LPS, 3) static culture, 4) static culture plus LPS. TNF-alpha (L929 cytotoxicity assay) was significantly increased in LPS-induced HARV and static cultures, yet the increase was more pronounced in the static culture group (p<0.05). A decrease in insulin concentration was demonstrated in the LPS stimulated HARV culture (p<0.05). We observed a greater glucose concentration and increased disappearance of arginine in islets cultured in HARVs. While nitrogenous compound analysis indicated a ubiquitous reliance upon glutamine in all experimental groups, arginine was converted to ornithine at a two-fold greater rate in the islets cultured in the HARV microgravity model system (p<0.05). These studies demonstrate alterations in LPS induced TNF-alpha production of pancreatic islets of Langerhans, favoring a lesser TNF activity in the HARV. These alterations in fuel homeostasis may be promulgated by gravity averaged cell culture methods or by three dimensional cell assembly.

Tobin, Brian W.↗

NASA NTRS2018

MPLA as an Innovative Immune Countermeasure

Spaceflight perturbs the human immune system. Among other manifestations, crewmembers may experience latent herpes viruses reactivation due to impaired lymphocyte function, as well as allergic/hypersensitivity reactions. Considering future space travel will be of longer duration (thereby increasing stress, exposure to radiation, etc…) with no rapid return option, it is of paramount importance to develop a countermeasure(s) to immune dysregulation. Monophosphoryl lipid A (MPLA) is a derivative of lipopolysaccharide (LPS), a potent inflammatory agent that can cause septic shock. MPLA possesses the immune-stimulatory effects of LPS without the adverse inflammatory effects. We hypothesize that treating immune cells with MPLA will boost their function enough to overcome the inhibitory effects of microgravity. While MPLA has been tested as an adjuvant extensively in mice and preliminarily for human vaccines, it has never been assessed for efficacy in microgravity.

Makedonas, George↗

DOE OSTI2021

Role of NLR family pyrin domain-containing 3 inflammasome in the activation of pancreatic stellate cells

Highlights: • NLRP3 inflammasome was activated with the extension of activation time of PSCs. • LPS triggered PSCs activation through activating NLRP3 Inflammasome. • Inhibition of NLRP3 inflammasome mitigates the activation of PSCs. • NLRP3 inflammasome activates the TGF-β1/Smad3 signaling pathway in PSCs. NLRP3 inflammasome activation plays an important role in the development of pancreatic fibrosis. However, it is unclear whether the activation of the NLRP3 inflammasome is directly involved in the activation of Pancreatic stellate cells (PSCs). The aim of this study was to investigate the role and mechanism of the NLRP3 inflammasome in the activation of PSCs. In vivo, a rat model of chronic pancreatitis (CP) was induced by intravenous injection of dibutyltin dichloride (DBTC). In vitro, rat primary PSCs were isolated from pancreatic tissues and incubated with the NLRP3 inflammasome activator LPS, the NLRP3 inhibitor MCC950, or NLRP3 siRNA. The results showed that the expression of NLRP3, pro-Caspase-1, Caspase-1 and IL-18 was increased in the rat model of CP and during PSCs activation. LPS increased the protein levels of NLRP3, ASC, Caspase-1, IL-1β and IL-18 accompanied by the upregulation of α-SMA, Col I and FN expression. Moreover, MCC950 or NLPR3 siRNA decreased the expression of α-SMA, Col I, FN, TGF-β1 and p-Smad3. Furthermore, MCC950 reversed the LPS-induced upregulation of α-SMA, FN and Col Ⅰ expression in PSCs. This study revealed that the NLRP3 inflammasome is directly involved in the activation of PSCs in vivo and in vitro. Inhibiting NLRP3 suppresses the activation of PSCs through the TGF-β1/Smad3 pathway.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2021

Necrosulfonamide reverses pyroptosis-induced inhibition of proliferation and differentiation of osteoblasts through the NLRP3/caspase-1/GSDMD pathway

The acute inflammatory stimulation occurring after a bone fracture regulates the repair and healing of local bone injury; however, under certain conditions, pyroptosis may occur in osteoblasts, which affects osteoblast proliferation and differentiation, thereby affecting the growth, development and morphological changes of bone tissue. The aim of the present study was to examine the effect of the pyroptosis inhibitor necrosulfonamide (NSA) on the proliferation and differentiation of osteoblasts and elucidate the underlying mechanism. The results revealed that NSA reversed the effects of ATP/lipopolysaccharide (LPS) on cell viability and pyroptosis, and on the mRNA and protein expression of pyroptosis-related genes. It also suppressed the secretion of IL-6, TNF-α and IL-1β and reversed the effects of ATP/LPS on the activity of ALP and the mRNA expression of differentiation-related genes in osteoblasts. The fact that overexpression of caspase-1, gasdermin D (GSDMD) and NLRP3 abolished the effects of NSA on the viability and pyroptosis of osteoblasts, as well as the mRNA expression of differentiation-related genes and the activity of ALP in osteoblasts, indicated that NSA promoted the proliferation and differentiation of osteoblasts by inhibiting the NLRP3/caspase-1/GSDMD pyroptosis pathway. The present study provides proof supporting the potential application of NSA for improving the function of osteoblasts in fracture repair and indicates the value of the NLRP3/caspase-1/GSDMD pyroptosis pathway as a pharmaceutical target.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2025

Evaluating the factors influencing accuracy, interpretability, and reproducibility in the use of machine learning classifiers in biology to enable standardization

The complexity and variability of biological data has promoted the increased use of machine learning methods to understand processes and predict outcomes. These same features complicate reliable, reproducible, interpretable, and responsible use of such methods, resulting in questionable relevance of the derived. outcomes. Here we systematically explore challenges associated with applying machine learning to predict and understand biological processes using a well- characterized in vitro experimental system. We evaluated factors that vary while applying machine learning classifers: (1) type of biochemical signature (transcripts vs. proteins), (2) data curation methods (pre- and post-processing), and (3) choice of machine learning classifier. Using accuracy, generalizability, interpretability, and reproducibility as metrics, we found that the above factors significantly mod- ulate outcomes even within a simple model system. Our results caution against the unregulated use of machine learning methods in the biological sciences, and strongly advocate the need for data standards and validation tool-kits for such studies.

59 BASIC BIOLOGICAL SCIENCES↗