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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Investigation of electrolyte measurement in diluted whole blood using spectroscopic and chemometric methods

The feasibility of using near-infrared (NIR) spectroscopy in combination with partial least-squares (PLS) regression was explored to measure electrolyte concentration in whole blood samples. Spectra were collected from diluted blood samples containing randomized, clinically relevant concentrations of Na+, K+, and Ca2+. Sodium was also studied in lysed blood. Reference measurements were made from the same samples using a standard clinical chemistry instrument. Partial least squares (PLS) was used to develop calibration models for each ion with acceptable results (Na+, R2 = 0.86, CVSEP = 9.5 mmol/L; K+, R2 = 0.54, CVSEP = 1.4 mmol/L; Ca2+, R2 = 0.56, CVSEP = 0.18 mmol/L). Slightly improved results were obtained using a narrower wavelength region (470-925 nm) where hemoglobin, but not water, absorbed indicating that ionic interaction with hemoglobin is as effective as water in causing measurable spectral variation. Good models were also achieved for sodium in lysed blood, illustrating that cell swelling, which is correlated with sodium concentration, is not required for calibration model development.

Non-NASA Center↗
NASA NTRS2003

Factors affecting the accuracy of near-infrared spectroscopy concentration calculations for focal changes in oxygenation parameters

Near-infrared spectroscopy (NIRS) can be used to noninvasively measure changes in the concentrations of oxy- and deoxyhemoglobin in tissue. We have previously shown that while global changes can be reliably measured, focal changes can produce erroneous estimates of concentration changes (NeuroImage 13 (2001), 76). Here, we describe four separate sources for systematic error in the calculation of focal hemoglobin changes from NIRS data and use experimental methods and Monte Carlo simulations to examine the importance and mitigation methods of each. The sources of error are: (1). the absolute magnitudes and relative differences in pathlength factors as a function of wavelength, (2). the location and spatial extent of the absorption change with respect to the optical probe, (3). possible differences in the spatial distribution of hemoglobin species, and (4). the potential for simultaneous monitoring of multiple regions of activation. We found wavelength selection and optode placement to be important variables in minimizing such errors, and our findings indicate that appropriate experimental procedures could reduce each of these errors to a small fraction (<10%) of the observed concentration changes.

Non-NASA Center↗
NASA NTRS1990

Mechanism of transport and distribution of organic solvents in blood

Little is known about the mechanism of transport and distribution of volatile organic compounds in blood. Studies were conducted on five typical organic solvents to investigate how these compounds are transported and distributed in blood. Groups of four to five rats were exposed for 2 hr to 500 ppm of n-hexane, toluene, chloroform, methyl isobutyl ketone (MIBK), or diethyl ether vapor; 94, 66, 90, 51, or 49%, respectively, of these solvents in the blood were found in the red blood cells (RBCs). Very similar results were obtained in vitro when aqueous solutions of these solvents were added to rat blood. In vitro studies were also conducted on human blood with these solvents; 66, 43, 65, 49, or 46%, respectively, of the added solvent was taken up by the RBCs. These results indicate that RBCs from humans and rats exhibited substantial differences in affinity for the three more hydrophobic solvents studied. When solutions of these solvents were added to human plasma and RBC samples, large fractions (51-96%) of the solvents were recovered from ammonium sulfate-precipitated plasma proteins and hemoglobin. Smaller fractions were recovered from plasma water and red cell water. Less than 10% of each of the added solvents in RBC samples was found in the red cell membrane ghosts. These results indicate that RBCs play an important role in the uptake and transport of these solvents. Proteins, chiefly hemoglobin, are the major carriers of these compounds in blood. It can be inferred from the results of the present study that volatile lipophilic organic solvents are probably taken up by the hydrophobic sites of blood proteins.

Solvents/administration & dosage/metabolism/pharma↗
NASA NTRS2012

Functional Near Infrared Spectroscopy: Watching the Brain in Flight

Functional Near Infrared Spectroscopy (fNIRS) is an emerging neurological sensing technique applicable to optimizing human performance in transportation operations, such as commercial aviation. Cognitive state can be determined via pattern classification of functional activations measured with fNIRS. Operational application calls for further development of algorithms and filters for dynamic artifact removal. The concept of using the frequency domain phase shift signal to tune a Kalman filter is introduced to improve the quality of fNIRS signals in realtime. Hemoglobin concentration and phase shift traces were simulated for four different types of motion artifact to demonstrate the filter. Unwanted signal was reduced by at least 43%, and the contrast of the filtered oxygenated hemoglobin signal was increased by more than 100% overall. This filtering method is a good candidate for qualifying fNIRS signals in real time without auxiliary sensors

Harrivel, Angela↗
NASA NTRS2012

Functional Near Infrared Spectroscopy: Watching the Brain in Flight

Functional Near Infrared Spectroscopy (fNIRS) is an emerging neurological sensing technique applicable to optimizing human performance in transportation operations, such as commercial aviation. Cognitive state can be determined via pattern classification of functional activations measured with fNIRS. Operational application calls for further development of algorithms and filters for dynamic artifact removal. The concept of using the frequency domain phase shift signal to tune a Kalman filter is introduced to improve the quality of fNIRS signals in real-time. Hemoglobin concentration and phase shift traces were simulated for four different types of motion artifact to demonstrate the filter. Unwanted signal was reduced by at least 43%, and the contrast of the filtered oxygenated hemoglobin signal was increased by more than 100% overall. This filtering method is a good candidate for qualifying fNIRS signals in real time without auxiliary sensors.

Harrivel, Angela↗
NASA NTRS2016

Carbon Monoxide Accumulation in the Extravehicular Mobility Unit

Introduction: Life support technology in large closed systems like submarines and space stations catalyzes carbon monoxide (CO) to carbon dioxide, which is easily removed. However, in a small system like the Extravehicular Mobility Unit (EMU), spacesuit, CO from exogenous (contaminated oxygen (O (sub 2) supply) and endogenous (human metabolism) sources will accumulate in the free suit volume. The free volume becomes a sink for CO that is rebreathed by the astronaut. The accumulation through time depends on many variables: the amount absorbed by the astronaut, the amount produced by the astronaut (between 0.28 and 0.34 moles per hour per kilogram)[1], the amount that enters the suit from contaminated O (sub 2), the amount removed through suit leak, the free volume of the suit, and the O (sub 2) partial pressure[2], just to list a few. Contamination of the EMU O (sub 2) supply with no greater than 1 part per million CO was the motivation for empirical measurements from CO pulse oximetry (SpCO) as well as mathematical modeling of the EMU as a rebreather for CO. Methods: We developed a first-order differential mixing equation as well as an iterative method to compute CO accumulation in the EMU. Pre-post measurements of SpCO (Rad-57, Masimo Corporation) from EMU ground training and on-orbit extravehicular activities (EVAs) were collected. Results: Initial modeling without consideration of the astronaut as a sink but only the source of CO showed that after 8 hours breathing 100 percent O (sub 2) with a 10 milliliter per minute (760 millimeters Hg at 21 degrees Centigrade standard) suit leak, an endogenous production rate of 0.23 moles per hour per kilogram for a 70 kilogram person with 42 liters (1.5 cubic feet) free suit volume resulted in a peak CO partial pressure (pCO) of 0.047 millimeters Hg at 4.3 pounds per square inch absolute (222 millimeters Hg). Preliminary results based on a 2008 model[3] with consideration of the astronaut as a sink and source of CO suggests that most of the rebreathed CO stays bound to hemoglobin and myoglobin and; therefore, pCO only increased to 0.002 millimeters Hg in the EMU. Hemoglobin saturation after 8 hours was an insignificant 0.4 percent compared to about 4 percent for cigarette smokers in the general population. This preliminary modeling result supplements 11 pre-post index finger SpCO measurements from EMU ground training (mean 0.5 percent versus 1 percent, probability equal to 0.41 from paired t-test) and 10 on-orbit pre-post EVAs (mean 1.5 percent versus 1.1 percent, probability equal to 0.17 from paired t-test) that showed no consistent increase, at least no increase outside the accuracy of the oximeter (1 percent display resolution with plus or minus 3 percent Standard Deviation). Discussion: Simulations continue, but a preliminary conclusion is that rebreathing endogenous CO accumulating in the EMU is not a serious medical issue during EVA. The absence of CO poisoning signs or symptoms following hundreds of EVAs is also good empirical evidence that corroborates the limited SpCO measurements and preliminary modeling results.

Conkin, J.↗
DOE OSTI2025

Optimal production of Phanerochaete chrysosporium manganese peroxidases and Trametes sp. C30 laccase hybrid Lac131 in Aspergillus niger for lignin bioconversion

Background Incorporating the production of related ligninolytic enzymes into industrial filamentous fungus Aspergillus niger will enhance the bioconversion of lignocelluloses to various chemical products. Results In this study, transgenic expression of Phanerochaete chrysosporium manganese peroxidases (mnps) and Trametes sp. C30 laccase hybrid Lac131 (lac131) were examined and optimized in A. niger 11414 prtT∆ strain. Five mnps (mnp1, mnp2, mnp3, mnp4, and mnp5) and lac131 genes were expressed separately or in combination. The transgenic strain containing the entire mnp2 genomic coding sequence (gmnp2) exhibited the highest mnP activity among the five mnp over-expression strains in the modified minimal medium (mMM) with addition of 5 g/L bovine hemoglobin (bHg). We examined the effects of hemin and bHg on mnP production in the gmnp2 strain cultures and found that at least 1 g/L bHg was required, while hemin was not. Culture conditions for mnP production were further optimized for the gmnp2 strain and the highest mnP activities were detected in the cultures grown at 25 °C and 200 rpm with an initial pH of 4.5. Effects of soy protein, skim milk, and bovine serum albumin on mnP production were investigated; 5 g/L of soy proteins or skim milk had comparable effects to 2.5 g/L bHg, while cultures with bovine serum albumin had diminished mnP activity. Disruption of both prtT and vsm1 substantially augmented the mnP production and its activity reached 575 U/L. Trametes sp. C30 laccase hybrid lac131 was strongly expressed in either A. niger gmnp2 (1975 U/L) or 11414prtT∆ (3895 U/L) strain. Both mnP and laccase in the culture supernatants effectively decolorized selected phenolic compounds (dyes) and cleaved tagged model lignin dimers. Conclusion The mnP was successfully produced in A. niger by optimizing the culture conditions and host strain. Co-expression of all four mnp genes in the same expression host by multiplex CRISPR will lead to the mnP production reaching levels comparable to P. chrysosporium, while only requiring 36 h at 25 °C. The Lac131 activity in transgenic A. niger strain is 4- to 7-times higher than that in previous studies. Co-production of mnP and laccase in A. niger will enhance the lignin bioconversion efficiency.

Aspergillus niger↗
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 NTRS1997

NMR of laser-polarized 129Xe in blood foam

Laser-polarized 129Xe dissolved in a foam preparation of fresh human blood was investigated. The NMR signal of 129Xe dissolved in blood was enhanced by creating a foam in which the dissolved 129Xe exchanged with a large reservoir of gaseous laser-polarized 129Xe. The dissolved 129Xe T1 in this system was found to be significantly shorter in oxygenated blood than in deoxygenated blood. The T1 of 129Xe dissolved in oxygenated blood foam was found to be approximately 21 (+/-5) s, and in deoxygenated blood foam to be greater than 40 s. To understand the oxygenation trend, T1 measurements were also made on plasma and hemoglobin foam preparations. The measurement technique using a foam gas-liquid exchange interface may also be useful for studying foam coarsening and other liquid physical properties.

Non-NASA Center↗
DOE OSTI2025

Structural basis of heme scavenging by the ChtA and HtaA hemophores in Corynebacterium diphtheriae

Corynebacterium diphtheriae causes diphtheria, a potentially fatal infectious disease that damages tissues in the upper respiratory tract. In order to proliferate, this pathogen acquires the essential nutrient iron from heme (iron-protoporphyrin IX) primarily found in human hemoglobin (Hb). C. diphtheriae secretes ChtA and HtaA hemophore proteins that bind ferric heme (hemin) via conserved region (CR) domains. Here, we demonstrate that their CR domains scavenge hemin after it is spontaneously released from Hb, and define the structural basis of hemin binding to ChtA and the N-terminal CR domain from HtaA by determining X-ray crystal structures of their protein-hemin complexes. Resonance Raman and electron paramagnetic resonance experiments demonstrate that the CR domains from ChtA and HtaA engage in pentacoordinate hemin binding through a conserved iron-tyrosyl linkage, though variations in their hemin pockets alter the way they stabilize the axial tyrosine and mask hemin’s metal. The importance of these interactions is probed using isothermal titration calorimetry experiments, which represent the first quantitative assessment of CR-hemin affinity and reveal that ChtA binds hemin via an enthalpically driven process. Hemin partitioning experiments using native mass spectrometry demonstrate that the cohort of CR domains within C. diphtheriae ’s hemin-uptake system have dissociation constants for hemin between 0.8 and 22 nM, raising the possibility that affinity differences contribute to the directional flow of hemin into the cell. Collectively, the results of this work provide insight into how C. diphtheriae and other pathogenic and commensal corynebacterium species utilize CR domains to scavenge iron rich hemin from their environment.

Corynebacterium diphtheriae↗
DOE OSTI2025

Spatial top-down proteomics for the functional characterization of human kidney

Background: The Human Proteome Project has credibly detected nearly 93% of the roughly 20,000 proteins which are predicted by the human genome. However, the proteome is enigmatic, where alterations in amino acid sequences from polymorphisms and alternative splicing, errors in translation, and post-translational modifications result in a proteome depth estimated at several million unique proteoforms. Recently mass spectrometry has been demonstrated in several landmark efforts mapping the human proteoform landscape in bulk analyses. Herein, we developed an integrated workflow for characterizing proteoforms from human tissue in a spatially resolved manner by coupling laser capture microdissection, nanoliter-scale sample preparation, and mass spectrometry imaging. Results: Using healthy human kidney sections as the case study, we focused our analyses on the major functional tissue units including glomeruli, tubules, and medullary rays. After laser capture microdissection, these isolated functional tissue units were processed with microPOTS (microdroplet processing in one-pot for trace samples) for sensitive top-down proteomics measurement. This provided a quantitative database of 616 proteoforms that was further leveraged as a library for mass spectrometry imaging with near-cellular spatial resolution over the entire section. Notably, several mitochondrial proteoforms were found to be differentially abundant between glomeruli and convoluted tubules, and further spatial contextualization was provided by mass spectrometry imaging confirming unique differences identified by microPOTS, and further expanding the field-of-view for unique distributions such as enhanced abundance of a truncated form (1-74) of ubiquitin within cortical regions. Conclusions: We developed an integrated workflow to directly identify proteoforms and reveal their spatial distributions. Where of the 20 differentially abundant proteoforms identified as discriminate between tubules and glomeruli by microPOTS, the vast majority of tubular proteoforms were of mitochondrial origin (8 of 10) where discriminate proteoforms in glomeruli were primarily hemoglobin subunits (9 of 10). These trends were also identified within ion images demonstrating spatially resolved characterization of proteoforms that has the potential to reshape discovery-based proteomics because the proteoforms are the ultimate effector of cellular functions. Applications of this technology have the potential to unravel etiology and pathophysiology of disease states, informing on biologically active proteoforms, which remodel the proteomic landscape in chronic and acute disorders.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Diabetes-specific formula with standard of care improves glycemic control, body composition, and cardiometabolic risk factors in overweight and obese adults with type 2 diabetes: results from a randomized controlled trial

Background and aims Medical nutrition therapy is important for diabetes management. This randomized controlled trial investigated the effects of a diabetes-specific formula (DSF) on glycemic control and cardiometabolic risk factors in adults with type 2 diabetes (T2D). Methods Participants ( n = 235) were randomized to either DSF with standard of care (SOC) (DSF group; n = 117) or SOC only (control group; n = 118). The DSF group consumed one or two DSF servings daily as meal replacement or partial meal replacement. The assessments were done at baseline, on day 45, and on day 90. Results There were significant reductions in glycated hemoglobin (−0.44% vs. –0.26%, p = 0.015, at day 45; −0.50% vs. −0.21%, p = 0.002, at day 90) and fasting blood glucose (−0.14 mmol/L vs. +0.32 mmol/L, p = 0.036, at day 90), as well as twofold greater weight loss (−1.30 kg vs. –0.61 kg, p < 0.001, at day 45; −1.74 kg vs. –0.76 kg, p < 0.001, at day 90) in the DSF group compared with the control group. The decrease in percent body fat and increase in percent fat-free mass at day 90 in the DSF group were almost twice that of the control group (1.44% vs. 0.79%, p = 0.047). In addition, the percent change in visceral adipose tissue at day 90 in the DSF group was several-fold lower than in the control group (−6.52% vs. –0.95%, p < 0.001). The DSF group also showed smaller waist and hip circumferences, and lower diastolic blood pressure than the control group (all overall p ≤ 0.045). Conclusion DSF with SOC yielded significantly greater improvements than only SOC in glycemic control, body composition, and cardiometabolic risk factors in adults with T2D.

Tey, Siew Ling↗