Aerospace medicine and biology: A continuing bibliography with indexes (supplement 339)

This bibliography lists 105 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during July 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Dissecting flux balances to measure energetic costs in cell biology: techniques and challenges

Life is a nonequilibrium phenomenon: metabolism provides a continuous supply of energy that drives nearly all cellular processes. However, very little is known about how much energy different cellular processes use, i.e. their energetic costs. The most direct experimental measurements of these costs involve modulating the activity of cellular processes and determining the resulting changes in energetic fluxes. In this review, we present a flux balance framework to aid in the design and interpretation of such experiments, and discuss the challenges associated with measuring the relevant metabolic fluxes. We then describe selected techniques that enable measurement of these fluxes. Finally, we review prior experimental and theoretical work that has employed techniques from biochemistry and nonequilibrium physics to determine the energetic costs of cellular processes.Comment: 27 pages, 3 figure

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 184

This bibliography lists 139 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1978

Essence of Reducing Equivalent Transfer Powering Neutrophil Oxidative Microbicidal Action and Chemiluminescence

Neutrophil leukocytes provide first-line phagocytic defense against infection. Phagocyte locomotion to the site of infection, identification, and phagocytosis of the infecting microbe results in metabolically driven O2-dependent combustive microbicidal action. NADPH oxidase activity controls this respiratory burst metabolism. Its flavoenzyme character allows semiquinone-mediated crossover from two reducing equivalents (2RE) to 1RE transfer, as is necessary for univalent reduction of O2 to the acid hydroperoxyl radical (HO2) and its conjugate base, superoxide anion (O2−). RE transfer dynamics is considered from the perspectives of quantum and particle physics, as well as frontier orbital interactions. Direct disproportionation of HO2-O2− yields electronically excited singlet molecular oxygen (1O2*) and hydrogen peroxide (H2O2). Myeloperoxidase catalyzes H2O2-dependent 2RE oxidation of chloride (Cl−) to hypochlorite (OCl−). Direct nonenzymatic reaction of OCl− with an additional H2O2 yields Cl−, H2O, and 1O2*. Thus, for two 2RE metabolized through NADPH oxidase, a total of three 1O2* are possible. H2O2, OCl−, and 1O2* generated are all singlet multiplicity reactants and can participate in spin-allowed combustive oxygenations yielding light emission, that is, luminescence or chemiluminescence. The sensitivity of luminescence for measuring neutrophil redox activities is increased several orders of magnitude by introducing chemiluminigenic probes. Probes can be selected to differentiate oxidase from haloperoxidase activities

Potential for Development of an Escherichia coli—Based Biosensor for Assessing Bioavailable Methionine: A Review

Methionine is an essential amino acid for animals and is typically considered one of the first limiting amino acids in animal feed formulations. Methionine deficiency or excess in animal diets can lead to sub-optimal animal performance and increased environmental pollution, which necessitates its accurate quantification and proper dosage in animal rations. Animal bioassays are the current industry standard to quantify methionine bioavailability. However, animal-based assays are not only time consuming, but expensive and are becoming more scrutinized by governmental regulations. In addition, a variety of artifacts can hinder the variability and time efficacy of these assays. Microbiological assays, which are based on a microbial response to external supplementation of a particular nutrient such as methionine, appear to be attractive potential alternatives to the already established standards. They are rapid and inexpensive in vitro assays which are characterized with relatively accurate and consistent estimation of digestible methionine in feeds and feed ingredients. The current review discusses the potential to develop Escherichia coli-based microbial biosensors for methionine bioavailability quantification. Methionine biosynthesis and regulation pathways are overviewed in relation to genetic manipulation required for the generation of a respective methionine auxotroph that could be practical for a routine bioassay. A prospective utilization of Escherichia coli methionine biosensor would allow for inexpensive and rapid methionine quantification and ultimately enable timely assessment of nutritional profiles of feedstuffs

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 212

A bibliography listing 146 reports, articles, and other documents introduced into the NASA scientific and technical information system is presented. The subject coverage concentrates on the biological, psychological, and environmental factors involved in atmospheric and interplanetary flight. Related topics such as sanitary problems, pharmacology, toxicology, safety and survival, life support systems, and exobiology are also given attention

The influence of the Ukrainian phytocomposition "Balm Truskavets'" on parameters of neuro-endocrine-immune complex and biophotonics in humans with maladaptation

Background. Earlier we showed that the Ukrainian phytocomposition “Balm Truskavets’” exerts immediate modulating effects on parameters of EEG and HRV as well as biophotonics. In a pilot study on 10 volunteers, we found that the use of the phytocomposition for 11 days causes changes in EEGs parameters accompanied by a sympatho(adreno)mimetic effect. The modulating effects on the EEG&HRV parameters are combined with the changes in biophotonics parameters. This study was conducted on a four times larger cohort and with a wider range of methods. Materials and Methods. The object of observation were 16 women 46±15 ys and 24 men 50±11 ys. The volunteers were practically healthy, but the initial testing revealed deviations from the norm in a number of parameters of the neuro-endocrine-immune complex as a manifestation of maladaptation. The adaptation hormones levels, Popovych’s leukocytary adaptation and strain indices, parameters of phagocytosis, biophotonics, acupuncture points, EEG and HRV, before and after a 9-day course of use of phytocomposition registered. Results. A noticeable effect of the phytocomposition on 38 parameters was revealed, grouped into 6 clusters, of which 4 are enhancing and 2 are reducing. In particular, the reduced levels of the adaptation index and phagocytosis parameters increase significantly, instead, the increased levels of the strain index, testosterone, triiodothyronine, LF band HRV as well as two biophotonics parameters decrease, that is, there is a normalizing/beneficial effect. At the same time, normal levels of HRV-markers of vagal tone decrease, and cortisol and circulating catecholamines as well as the activity of β- and α-rhythm generating neurons increase, but within the normal range. Finally, there is a further increase in the upper limit levels of activity of δ-rhythm generating neurons. Conclusion. Ukrainian phytocomposition “Balm Truskavets’” exerts classical adaptogenic effects on parameters of neuro-endocrine-immune complex as well as biophotonics and acupuncture in humans with maladaptation

On the reactivity of nanoparticulate elemental sulfur : experimentation and field observations

Indiana University-Purdue University Indianapolis (IUPUI)The reaction between elemental sulfur and sulfide is a lynchpin in the biotic and abiotic cycling of sulfur. This dissertation is focused on the reactivity of elemental sulfur nanoparticles (S8weimarn, S8raffo) among other forms of elemental sulfur (S8aq, S8aq-surfactant, α-S8), and how the variation of their surface area, character and coatings reflect on the analytical, physical-chemical and geochemical processes involving sulfur cycling. A comprehensive electrochemical investigation utilizing mercury-surface electrodes showed that elemental sulfur compounds are represented by three main voltammetric signals, corresponding to potentials at -1.2V, -0.8V, and -0.6V in the absence of organics at circumneutral pH. Dissolved S8aq-surfactant signals can be found from -0.3V up to -1.0V, depending on the surfactant in the system. Variations in current response resulted from differences in electron transfer efficiency among the forms of S8, due to their molecular structural variability. Based on this observation a new reaction pathway between S8 and Hg-surface electrodes is proposed, involving an amalgam-forming intermediate step. The kinetics of the nucleophilic dissolution of S8nano by sulfide, forming polysulfides, were investigated under varying surface area, surface character and presence or absence of surfactant coatings on S8nano. Hydrophobic S8weimarn and hydrophilic S8raffo show kinetic rate laws of 8 = 10−11.33 ( −700.65 ) (Molar(S8)/second/dm-1) and8 = 10−4.11 −0.35 ( −615.77 ) (Molar(S8)/second), respectively. The presence of surfactant molecules can influence the reaction pathways by dissolving S8nano and releasing S8aqsurfactant, evolving the rate-limiting step as a function of the degree of the solubilization of S8nano. The reaction rate of S8biological can be compared with those of S8raffo and S8weimarn in circumneutral pH values and T=50oC, making the forms of S8nano successful abiotic analogue models of microbially produced S8biological. Field observations and geochemical kinetic modeling in the geothermal features of Yellowstone indicate that the nucleophilic dissolution reaction appears to be a key abiotic pathway for the cycling of sulfur species and the enhancement of elemental sulfur bioavailability. Furthermore, in situ and ex situ voltammetry in the same geothermal waters disclosed chaotic variability in chemical gradients of sulfide (observed over small temporal and spatial scales) which can be considered as an ecological stressor capable of influencing single cell physiology and microbial community adaptation

Faunal response to benthic and hyporheic sedimentation varies with direction of vertical hydrological exchange

1. Sedimentation and clogging of benthic and hyporheic zone substrates is increasingly being recognised as one of the greatest threats to the ecological integrity of riverine ecosystems globally. This ex-situ study examined the influence of sedimentation (benthic and hyporheic) and pattern of hydrological exchange on the vertical distribution of the freshwater shrimp Gammarus pulex within the experimental substrates of running water mesocosms. 2. Six sediment treatments representing a continuum from a clean gravel substratum through to heavy sediment loading of both benthic and hyporheic substrates were used to examine the distribution of G. pulex in relation to the direction of hydrological exchange (downwelling, upwelling and no exchange). 3. The vertical distribution of fauna varied significantly for both sediment treatment and pattern of hydrological exchange. There was a significant interaction between the two effects indicating that the effect of sedimentation varied depending on the pattern of vertical hydrological exchange