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PubMed1998

Abiotic formation of bioorganic compounds in space--preliminary experiments on ground and future exobiology experiments in space.

Simulation experiments on ground have shown that "amino acid precursors", which give amino acids after acid-hydrolysis, can be formed when an ice mixture simulating ice mantles of interstellar dust particles (lSDs) is irradiated with high energy particles or UV light. It is strongly suggested that such bioorganic compounds were delivered by comets for the first biosphere on the Earth. It is of great interest to confirm this hypothesis in actual space conditions, such as in an exposed facility of JEM. Fundamental designs for such exobiology experiments in earth orbit (EEEO) will be discussed.

Amino Acids↗
PubMed1992

Emergency medical operations at Kennedy Space Center in support of space shuttle.

The unique environment of the Kennedy Space Center includes a wide variety of industrial processes culminating in launch and spaceflight. Many are potentially hazardous to the work force and the astronauts. Technology, planning, training, and quality control are utilized to prevent contingencies and expedite response should a contingency occur.

Aerospace Medicine↗
PubMed2005

Space life sciences: closed ecological systems: earth and space applications.

This issue contains peer-reviewed papers from a workshop on Closed Ecological Systems: Earth and Space Applications at the 35th COSPAR General Assembly in Paris, France, convened in July 2004. The contributions reflected the wide range of international work in the field, especially Europe, Russia, Japan, and the United States. The papers are arranged according to four main themes: 1) Methods of evaluation and theory of closed ecological systems; 2) Reports from recent experiments in closed ecological system facilities; 3) Bioregenerative technologies to advance degree of closure and cycling; and 4) Laboratory studies of small closed ecological systems.

Aquaculture↗
PubMed1991

[Invariance in relation to transformations: a comparison of space perception and imagined space].

The present paper is based on the assumption of a functional equivalence between the processes of perception and imagination and a functional isomorphism between physical and phenomenal relations. The intention is to look for systematic deviations between 'measured', 'perceived' and 'imagined' space. Therefore a room was equipped with 32 pieces of furniture, giving it the appearance of a combined library and study room. A miniature model (1:10) of the room was constructed. In a two-factorial design with 10 experimental conditions, subjects performed model-reconstructions. The first factor refers to cognitive modality and represents different amounts of information of the physical layout, the endpoints of the continuum being 'complete insight' and 'no insight'. The second factor is a rotation of the model during the reconstruction (0 degrees vs. 180 degrees). Data analysis is based on location and orientation measures of the objects and distinguishes between 'semantic' and 'geometric' errors. The main results are: Even under conditions of only partial insight the spatial relations of the missing objects can be consensually reconstructed. While the absolute amount of the reconstruction errors largely depends on the two factors (modality and rotation), substantial relations of the original room are preserved under the different experimental conditions. The results are in good accordance with the assumption of functional equivalence and are critically discussed with respect to the concept of functional isomorphism.

Adult↗
PubMed1989

Space vehicle approach velocity judgments under simulated visual space conditions.

There were 35 volunteers who responded when they first perceived an increase in apparent size of a collimated, two-dimensional perspective image of an Orbiter vehicle. The variables of interest included the presence (or absence) of a fixed reticle within the field of view (FOV), background starfield velocity, initial range to the vehicle and vehicle closure velocity. It was found that: 1) increasing vehicle approach velocity yielded a very small (but significant) effect of faster detection of vehicle movement, nevertheless, response variability was relatively large; 2) including the fixed reticle in the FOV produced significantly slower detection of vehicle radial movement, however this occurred only at the largest range and the magnitude of the effect was only about 15% of the one sigma value; and 3) increasing background star velocity during this judgment led to slower detection of vehicle movement. While statistically significant, this effect was small and occurred primarily at the largest range. A possible explanation for the last two findings is that other static and dynamic objects within the visual field may compete for available attention which otherwise would be available for judging image expansion; thus, the target's retinal image has to expand more than otherwise for its movement to be detected. This study also showed that the Proximity Operations Research Mockup at NASA/Ames can be used effectively to investigate a variety of visual judgment questions related to future space operations. These findings are discussed in relation to previous research and possible underlying mechanisms.

Adult↗
PubMedDate not supplied

[Body fluid and electrolyte content in rat tissues after space flight in the "Space-2044" spacecraft].

Contents of water, sodium, calcium and magnesium in different tissues of the rats stayed in space for 2 weeks in healing period of bone fracture following graded trauma of calf-bones as well as in the rats exposed to a head-down suspension (HDS) have been studied. In microgravity-exposed animals there were no significant changes in fluid-electrolyte composition of the liver, kidney, myocardium, skin, bone (calf bone). Specific "functional load" on the system of fluid-electrolyte homeostasis in the form of operation and subsequent healing of bone fracture did not result in additional changes in fluid and electrolyte contents of body tissues. In the HDS animals there was a significant change in fluid-electrolyte composition of skin, kidney and bone tissue.

Animals↗
PubMed1988

Effects of perfusate flow rate on measured blood volume, disse space, intracellular water space, and drug extraction in the perfused rat liver preparation: characterization by the multiple indicator dilution technique.

The effect of hepatic blood flow on the elimination of several highly cleared substrates was studied in the once-through perfused rat liver preparation. A constant and low input concentration of ethanol (2.0 mM), [14C]-phenacetin and [3H]-acetaminophen (0.36 and 0.14 microM, respectively), or meperidine (8.1 microM) was delivered once-through the rat liver preparation in five flow periods (greater than 35 min each); control flow periods at 12 ml/min were interrupted by flow changes to 8 or 16 ml/min. The steady-state hepatic availabilities (F or outflow survivals) at 12 ml/min were ethanol, 0.075 +/- 0.038; [14C]-phenacetin, 0.15 +/- 0.059; [3H]-acetaminophen, 0.34 +/- 0.051; meperidine, 0.047 +/- 0.017. Flow-induced changes were different among the compounds: with reduced flow (8 ml/min), F was decreased for ethanol (0.061 +/- 0.032) and [3H]-acetaminophen (0.28 +/- 0.051), as expected, but was increased for [14C]-phenacetin (0.20 +/- 0.068) and meperidine (0.05 +/- 0.03); with an elevation of flow (to 16 ml/min), F was increased for all compounds, as expected of shorter sojourn times: ethanol, 0.13 +/- 0.065; [14C]-phenacetin, 0.22 +/- 0.062; [3H]-acetaminophen, 0.43 +/- 0.063; meperidine, 0.055 +/- 0.022. A marked increase in F for ethanol had occurred when flow changed from 12 to 16 ml/min due to nonlinear metabolism; the latter was confirmed by a reduction in the extraction ratios at increasing concentrations (1.8 to 11.4 mM); this condition was not present for the other compounds. In order to explain the observations, we used the multiple indicator dilution technique to investigate the flow-induced behaviors of tissue distribution spaces of vascular and intracellular references in the perfused rat liver preparation.

Acetaminophen↗
PubMed1992

The ionic strength of the intermembrane space of intact mitochondria is not affected by the pH or volume of the intermembrane space.

Ionic strength affects the electron transport activity of cytochrome c through its electrostatic interactions with redox partners and membrane lipids. We previously reported (Cortese, J.D., Voglino, A.L. and Hackenbrock, C.R. (1991) J. Cell Biol. 113, 1331-1340) that the ionic strength (I) of the intermembrane space (IMS-I) in isolated, intact condensed mitochondria is similar to the external, bulk I, over a wide range of bulk I. We now consider the possible effects of IMS-pH and IMS-volume, both variable parameters of mitochondrial function in situ, on IMS-I. IMS-pH and IMS-I were measured with pH- and I-sensitive fluorescent probes (highly fluorescent FITC-dextran for IMS-pH and FITC-BSA for IMS-I). These probes were delivered into the IMS of intact mitochondria via probe encapsulation into asolectin vesicles, followed by low pH-induced fusion of the vesicles with the outer membranes of intact mitochondria. IMS-pH was found to be 0.4-0.5 units lower than bulk pH over the pH range 6.0-8.5 for mitochondria with a large IMS-volume separating the two mitochondrial membranes (condensed configuration), and 0-0.2 units lower for mitochondria with a small IMS-volume and membranes closely opposed (orthodox configuration). This small pH difference between IMS-pM and bulk pH did not influence the similarity between IMS-I and bulk I. When the IMS-volume was osmotically decreased, bringing the two mitochondrial membranes in close proximity as in the orthodox configuration, IMS-I followed the bulk I above 10 mM but did not respond to changes in bulk I below 10 mM. The lack of response of the IMS-I below 10 mM indicates that the close proximity of the two mitochondrial membranes excludes ions only at low, nonphysiological I. Since the similarity of IMS-I and bulk I is unaffected by either IMS-pH or IMS-volume above a bulk I of 10 mM, at cytosolic physiological I (i.e., 100-150 mM) cytochrome c can be expected to be a free, three-dimensional diffusant in the IMS irrespective of the pH or volume of the IMS.

Animals↗
PubMedDate not supplied

New results for the space radiation environment of MIR space station obtained by Liulin dosimeter-radiometer. Comparison with LET spectrometer NAUSICAA.

Since 1988 high sensitivity semiconductor dosimeter-radiometer "Liulin" worked on board of MIR space station. Device measured the absorbed dose rate and the flux of penetrating particles. The analysis of the data shows the following new results: In October 1989 and after March 24, 1991, two additional stable maximums in flux channel were observed in the southern-eastern part of South Atlantic Anomaly (SAA). These two maximums existed at least several months and seem to be due to trapped high energy electron and proton fluxes. In April 1991 additional maximums were localized in the following geographical coordinates regions: latitude = (-35 degrees)-(-50 degrees) longitude = 332 degrees-l6 degrees and lat.(-46 degrees)-(-52 degrees) long. 360 degrees-60 degrees. Additional maximums diffusion occurs inside radiation belt. Appearance of these maximums seems to be closely connected with preceding powerful solar proton events and associated geomagnetic dynamics of new belt disturbances. Alter the series of solar proton events in June 1991 we observed significant enhancement of this new radiation belt formation. To achieve sufficient accuracy of dose rate predictions in low Earth orbits the structure and dynamics of new belt should be carefully analyzed to be included in a new environment model. From the inter comparison of the data from "Liulin" and French developed tissue equivalent LET spectrometer NAUSICAA in the time period August-November 1992 we come to the following conclusions: Mainly there is good agreement between both data sets for absorbed dose in the region of SAA; Different situation of the instruments on the station can explain the cases when differences up to 2 times are observed; At high latitudes usually the tissue equivalent absorbed dose observations are 2 times larger than "Liulin" doses.

Atlantic Ocean↗
PubMed1993

The effect of the lattice spacing change on cross-bridge kinetics in chemically skinned rabbit psoas muscle fibers. II. Elementary steps affected by the spacing change.

The actin-myosin lattice spacing of rabbit psoas fibers was osmotically compressed with a dextran T-500, and its effect on the elementary steps of the cross-bridge cycle was investigated. Experiments were performed at the saturating Ca (pCa 4.5-4.9), 200 mM ionic strength, pH 7.0, and at 20 degrees C, and the results were analyzed by the following cross-bridge scheme: [formula: see text] where A = actin, M = myosin head, S = MgATP, D = MgADP, and P = Pi = phosphate. From MgATP and MgADP studies on exponential process (C) and (D), the association constants of cross-bridges to MgADP (K0), MgATP (K1a), the rate constants of the isomerization of the AM S state (k1b and k-1b), and the rate constants of the cross-bridge detachment step (k2 and k-2) were deduced. From Pi study on process (B), the rate constants of the cross-bridge attachment (power stroke) step (k4- and k-4) and the association constant of Pi ions to cross-bridges (K5) were deduced. From ATP hydrolysis measurement, the rate constant of ADP-isomerization (rate-limiting) step (k6) was deduced. These kinetic constants were studied as functions of dextran concentrations. Our results show that nucleotide binding, the ATP-isomerization, and the cross-bridge detachment steps are minimally affected by the compression. The rate constant of the reverse power stroke step (k-4) decreases with mild compression (0-6.3% dextran), presumably because of the stabilization of the attached cross-bridges in the AM*DP state. The rate constant of the power stroke step (k4) does not change with mild compression, but it decreases with higher compression (> 6.3% dextran), presumably because of an increased difficulty in performing the power stroke. These results are consistent with the observation that isometric tension increases with a low level of compression and decreases with a high level of compression. Our results also show that the association constant K5 of Pi with cross-bridge state AM*D is not changed with compression. Our result further show that the ATP hydrolysis rate decreased with compression, and that the rate constants of the ADP-isomerization step (k6) becomes progressively less with compression. The effect of compression on the power stroke step and rate-limiting step implies that a large-scale molecular rearrangement in the myosin head takes place in these two slow reaction steps.

Actins↗
PubMedDate not supplied

Neighborhood behavior of in silico structural spaces with respect to in vitro activity spaces--a benchmark for neighborhood behavior assessment of different in silico similarity metrics.

In a previous work, we have introduced Neighborhood Behavior (NB) criteria for calculated molecular similarity metrics, based on the analysis of in vitro activity spaces that simultaneously monitor the responses of a compound with respect to an entire panel of biologically relevant receptors and enzymes. Now, these novel NB criteria will be used as a benchmark for the comparison of different in silico molecular similarity metrics, addressing the following topics: (1) the relative performance of 2D vs 3D descriptors, (2) the importance of the similarity scoring function for a given descriptor set, and (3) binary or Fuzzy Pharmacophore Fingerprints-can they capture the similarity of the spatial distribution of pharmacophoric groups despite different molecular connectivity? It was found that fuzzy pharmacophore descriptors (FBPA) displayed an optimal NB and, unlike their binary counterparts, were successful in evidencing pharmacophore pattern similarity independently of topological similarity. Topological FBPA, identical to the former except for the use of topological instead of 3D atom pair distances, display a somehow weaker, but significant NB. Metrics based on "classical" global 2D and 3D molecular descriptors and a Dice scoring function also performed well. The choice of the similarity scoring function is therefore as important as the choice of the appropriate molecular descriptors.

Journal Article↗
PubMed2006

Does expanded retrieval produce benefits over equal-interval spacing? Explorations of spacing effects in healthy aging and early stage Alzheimer's disease.

Three experiments explored different schedules of retrieval practice in young adults, older adults, and individuals with dementia of the Alzheimer type. In each experiment, an initial acquisition phase was presented in which participants studied or attempted to retrieve response words to cues, followed by a later cued-recall test. Experiment 1 produced a benefit of expanded retrieval over equal-interval retrieval during acquisition, but this benefit was lost in final cued recall. In Experiments 2 and 3, participants received corrective feedback during acquisition and modified spacing schedules. There was again no evidence of a difference between expanded and equal-interval conditions in final cued recall. Discussion focuses on the potential benefits and costs of expanded retrieval on a theoretical and applied level.

Adolescent↗
PubMed1980

Inner space and outer space identity in contemporary females.

Historically, attempts to achieve experimental confirmation of hypotheses in psychoanalytic theory have been very limited. As Nelson (1976) has pointed out, the psychoanalytic literature is abundantly filled with articles and symposia dealing with the inherent difficulties of psychoanalytic research. This study represents an attempt to translate an area of analytic theory into an experimental paradigm and to use the paradigm in a test of the validity of the theory. The theory being tested in Erikson's (1968) theory of identity formation in females. The findings lead to a suggestion that Erikson's theory is in need of modification as a description of contemporary women. The study is discussed here in the context of Erikson's theory and the analytic writings on the female inner space.

Adolescent↗
PubMed1975

An investigation of space and space-time clustering in a large sample of infants with neural tube defects born in Cardiff.

Altogether 406 infants with neural tube defects born in Cardiff between 1956-71 were investigated for evidence of space-time clustering and 100 similarly affected infants, together with matched controls born in Cardiff between 1964-66 were investigated for evidence of spatial clustering. No evidence of excessive prevalence in either dimension was observed.

Anencephaly↗