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PubMed1996

Hormonal, water balance, and electrolyte changes during sixty-day confinement.

The EXEMSI experiment has made it clear that it is difficult to perform psychological and physiological protocols satisfactorily in the same study. It is, therefore, essential that the objectives of study be defined clearly before the start. While behavioral and psychological studies may be possible and provide valid results for a small group of mixed gender, it is more difficult to conduct valid physiological studies due to large differences between individuals and even in the same individual over time. As stated before, it is unusual in space research on humans and even during space simulation studies to have large and homogeneous groups of subjects. The consequence is that the results remain tentative. For a better understanding of the physiological data collected during the ISEMSI ad EXEMSI experiments, they should be correlated with the results of the psychological studies. One of the conclusions drawn from the ISEMSI experiment was that confinement provides a valuable parallel to other simulations of weightlessness, such as bedrest. The same pattern of changes in parameters like the blood volume regulating hormones renin and aldosterone was observed as in bedrest. After the EXEMSI study we can say that the conditions imposed by confinement, high work load, and stress, potentiate these effects. This implies that in using head-down bedrest as a weightlessness simulation the confinement effects must be identified by setting adequate control conditions for the head-down position, for short-term as well as for long-term simulations. Indeed, we have seen in the two isolation studies that confinement may have its effects at the beginning of the isolation period (EXEMSI) as well as during the entire isolation period (ISEMSI). In planning for EXEMSI we wanted to obtain more insight in some of the phenomena observed during ISEMSI by the introduction of new techniques such as the doubly labeled water method for determination of total body water. However, in some cases the opposite effects of those encountered in ISEMSI were found. This was probably due to the many changes in the experimental scenario, like number of subjects, mixed gender, living space per subject, and workload. Thus, for future isolation studies the operational scenario should be better examined and preferably standardized. Nevertheless, in such studies as well as in long-term sojourns in a space station, the crew size will not be larger than that of the EXEMSI crew. Physiologists will, therefore, have to become familiar with the study of small groups of subjects and to try to overcome the problems of large individual differences and statistical analysis of data from small groups.

Adult↗

PubMed2001

Interrelations between the small isolated groups with homogeneous and heterogeneous composition.

Increase in the heterogeneity of a space crew's composition (cultural and gender differences) is a risk factor that can negatively influence the formation of a cohesive crew, which depends on a common way of perceiving one's social environment, goals and values. Method. Three groups working in isolation from 110 to 240 days, all with different cultural and gender composition were analysed using a modification of Kelly's repertory grid technique during a space simulation at the Institute for Biomedical Problems, Moscow. Subjects assessed themselves and each other monthly. Results. National Russian and international groups failed to create a single cohesive crew. Members of both groups considered people from their group as "us" and their neighbours as "them". Their relations became more negative during the mission, with attitudes changing from neutral to poor. Subjects began to perceive each other as "different and distant". Cultural and language differences prevented national (Russian) and international groups from forming a common understanding of behavioural rules and establishing close emotional contacts. Conclusions. Differences in perception of the interpersonal environment, group goals and values in national and international groups hindered the formation of a joint cohesive crew.

Adaptation, Psychological↗

PubMed1997

An investigation into the placement of force delivery systems and the initial forces applied by clinicians during space closure.

This in vitro investigation was designed to establish not only how clinicians apply forces for space closure when using the straight wire appliance and sliding mechanics, but also to quantify the initial force levels produced. A single typodont, with residual extraction space in each quadrant, was set up to simulate space closure using sliding mechanics. On two occasions, at least 2 months apart, 18 clinicians were asked to apply three force delivery systems to the typodont, in the manner in which they would apply it in a clinical situation. The three types of force delivery system investigated were elastomeric chain, an elastomeric module on a steel ligature, and a nickel-titanium closed coil spring. A choice of spaced or unspaced elastomeric chain produced by a single manufacturer was provided. The amount of stretch which was placed on each type of system was measured and, using an Instron Universal Testing Machine, the initial force which would be generated by each force delivery system was established. Clinicians were assessed to examine their consistency in the amount of stretch which each placed on the force delivery systems, their initial force application and their ability to apply equivalent forces with the different types of force delivery system. The clinicians were found to be consistent in their method of application of the force delivery systems and, therefore, their force application, as individuals, but there was a wide range of forces applied as a group. However, most clinicians applied very different forces when using different force delivery systems. When using the module on a ligature the greatest force was applied, whilst the nickel titanium coil springs provided the least force.

Dental Alloys↗

PubMedDate not supplied

[Biological value of proteins in food rations of crews on Saliut orbital stations].

The biological value of the protein component of three modifications of the Salyut space diet was measured in laboratory studies and in simulated space flights. Three experimental runs of up to 68 days in duration were carried out on 20 volunteers. During the study the following parameters of protein metabolism were measured: total protein and protein fractions in serum; urea, uric acid and creatinine in blood; total nitrogen, urea, ammonia, uric acid and creatinine in urine. The results obtained showed that the diet modifications provided an adequate nutritional status and a normal level of the above parameters of protein metabolism.

Amino Acids↗

PubMed1996

Fundamental studies concerning planetary quarantine in space.

If there is a possibility that the organisms carried from Earth to space can live for a significant period on planets, the contamination of planets should be prevented for the purpose of future life-detection experiments. In connection with quarantine for interplanetary missions, we have examined the survivabilities of terrestrial microorganisms under simulated space conditions. In this study, examined the survivabilities of terrestrial organisms under simulated Mars conditions. The Mars conditions were simulated by ultraviolet (UV) and proton irradiation under low temperature, high vacuum, and simulated gaseous conditions. After exposure to the simulated Mars condition, the survivabilities of the organisms were examined. The spores of Bacillus subtilis and Aspergillus niger, some anaerobic bacterias and algaes, showed considerably high survivabilities even after UV and proton irradiation corresponding to 200 years on Mars. This subject is not restricted to academic curiosity but concerns problems involving the contamination of Mars with terrestrial organisms carried by space-probes.

Bacteria↗

PubMedDate not supplied

Rational combinatorial library design. 1. Focus-2D: a new approach to the design of targeted combinatorial chemical libraries.

We describe a new computational approach, called Focus-2D, to the rational design of targeted combinatorial chemical libraries. This approach is based on the hypothesis that structurally similar compounds display similar biological activity profiles. Building blocks that are used in a combinatorial chemical synthesis are randomly assembled to produce virtual library compounds. Individual library compounds are represented by Kier-Hall topological descriptors. Molecular similarities between compounds are evaluated quantitatively by modified pairwise Euclidean distances in multidimensional descriptor space. Simulated annealing is used to search the potentially large structural space of virtual chemical libraries to identify compounds similar to lead molecules. Frequency analysis of building block composition of selected virtual compounds identifies building blocks that can be used in combinatorial synthesis of chemical libraries with high similarity to the lead molecules. We show that this method correctly identifies building found in active peptoids with adrenergic or opioid activities.

Drug Design↗

PubMed1994

Intrapleural omentum simulating pleural effusion.

We report herein a case of Morgagni hernia of omentum into the pleural space, simulating a pleural effusion on a routine chest radiograph. A 62-year-old man was referred to our clinic for close examination of a pleural effusion-like shadow at the right costophrenic region. He had no history of trauma and no symptoms. Chest computed tomographic scan showed a pleural effusion-like shadow with a fat density. Thoracoscopy revealed a movable omentum-like mass and no significant fluid in the right pleural space. Magnetic resonance imaging and celiac angiography confirmed the herniation of omentum into the right pleural space. This case suggests that a Morgagni hernia must be excluded in a patient with a fat density effusion-like shadow in the pleural space.

Diagnosis, Differential↗

PubMed1987

Psychological and interpersonal issues in space.

As future manned space missions become longer, and as crews become more heterogeneous, psychological and interpersonal factors will take on increasing importance in assuring mission success. On the basis of a review of more than 60 American and Soviet space simulation studies on Earth, along with reports from U.S. and Soviet space missions, the author identifies nine psychological and seven interpersonal issues, which are discussed along with pertinent research findings and examples from manned spaceflights. He concludes that more psychological and interpersonal research should be done under actual spaceflight conditions and offers suggestions.

Adaptation, Psychological↗

PubMed1978

Radiobiological experiment aboard the biosatellite Cosmos-690.

In 1974, the USSR launched the biosatellite Cosmos-690 equipped with a gamma-irradiation unit that carried 35 rats. On the 10th flight day, the rats were exposed to radiation at doses of 220 or 800 rads. During the subsequent 10 d, radiation injury developed in a space environment. Similar ground-based experiments were carried out to simulate space flight environment effects. The results obtained were studied on a comparative basis. The conclusion is made that effects of a short-term space flight, as long as 20 d, do not essentially modify the radiobiological effect.

Animals↗

PubMed1998

[The study of biocide effectiveness of ultraviolet treatment in media stimulating space station environment].

An experiment was performed to study the biocide effect of ultraviolet treatment of simulated space station milieu. UV generated by low and moderately power-intensive sources (from 10 W to 1 kW) showed a good promise for decontaminating, within the reach, solid structural materials, and the air and water in the cabin. For instance, within 10 minutes of the UV-treatment aerial bacteria in 20 m3 were reduced in 12 to 30 times while fungal microflora was fully suppressed. Water containing spores and vegetative cells of both pathogenic and nonpathogenic microorganisms became essentially sterile after 4 to 10 minutes of treatment with low UV (in the order of 0.01 W/cm2). Different UV modalities can lay the basis for development of specific technologies of microbial decontamination of various spacecraft.

Decontamination↗

PubMed1986

Animal studies of life shortening and cancer risk from space radiation.

The U.S. Air Force study of the delayed effects of single, total body exposures to simulated space radiation in rhesus monkeys is now in its 21st year. Observations on 301 irradiated and 57 age-matched control animals indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events can be expressed as a logarithmic function of the dose. The primary causes of life shortening are cancer and endometriosis (an abnormal proliferation of the lining of the uterus in females). Life shortening estimates permit comparison of the risk associated with space radiation exposures to be compared with that of other occupational and environmental hazards, thereby facilitating risk/benefit decisions in the planning and operational phases of manned space missions. Calculations of the relative risk of fatal cancers in the irradiated subjects reveal that the total body surface dose required to double the risk of death from cancer over a 20-year post exposure period varies with the linear energy transfer (LET) of the radiation. The ability to determine the integrated dose and LET spectrum in space radiation exposures of humans is, therefore, critical to the assessment of lifetime cancer risk.

Animals↗

PubMed2001

Permanent depression of plasma cGMP during long-term space flight.

The purpose of this study was to investigate plasma concentrations of cyclic guanosine monophosphate (cGMP) and atrial natriuretic peptide (ANP) during and after real and simulated space flight. Venous blood was obtained 3 min after the beginning and 2 min after the lower body negative pressure maneuver in two cosmonauts preflight (supine), inflight, and postflight (supine) and in five other subjects before, at the end, and 4 days after a 5-day head-down tilt (-6 degrees) bed rest. In cosmonaut 1 (10 days in space), plasma cGMP fell from preflight 4.3 to 1.4 nM on flight day 6, and was 3.0 nM on the fourth day after landing. In cosmonaut 2 (438 days in space), it fell from preflight 4.9 to 0.5 nM on on flight day 3, and stayed <0.1 nM with 5, 9, and 14 months in space, as well as on the fourth day after landing. Three months after the flight his plasma cGMP was back to normal (6.3 nM). Cosmonaut 2 also displayed relatively low inflight ANP values but returned to preflight level immediately after landing. In a ground-based simulation on five other persons, supine plasma cGMP was reduced by an average of 30% within 5 days of 6 degrees head-down tilt bed rest. The data consistently demonstrate lowered plasma cGMP with real and simulated weightlessness, and a complete disappearance of cGMP from plasma during, and shortly after long-duration space flight.

Adult↗

PubMed1979

An exploration of perception of body boundary, personal space, and body size in elderly persons.

A study of 108 elderly persons using the Body Distortion Questionnaire and the personal space simulation technique test did not support hypotheses that elderly persons with a large personal space will have a larger distortion of body boundary, a larger perception of large body size, a smaller perception of small body size, a larger distortion of body size, and a larger body distortion than elderly persons with a small personal space. The analyses with one-tail t tests showed elderly persons with a small personal space have a larger perception of large body size and a larger distortion of body size than elderly persons with a large personal space. When the extremes of personal space were used the results were the same. Males have a larger personal space and greater distortion of skin perceptions than females.

Aged↗

PubMedDate not supplied

Bone and body mass changes during space flight.

Body mass, calcium and skeletal changes occur in humans who have worked in microgravity. Physiologic changes are seen as early as one week and are still occurring 312 days into space flight. The physiologic changes in bone and mineral metabolism may be among those which limits long duration space flight if an adequate countermeasure is not developed. The purpose of this paper is to summarize what is known about calcium dynamics and bone mineral changes as well as associated changes of body mass induced by space flight. The data reported is from a variety of studies conducted in both actual and simulated space flight.

Aerospace Medicine↗

PubMedDate not supplied

[Effect of actoprotectors on the work capacity of operators during modeling of various factors of space flight].

This paper presents experimental findings indicating that bemithyl, an actoprotective agent, has a beneficial effect on the health status and work capacity of operators during simulated space flight and 56-hour continuous work. The drug enhanced psychophysiological tolerance of the operators and improved the quality of their work: the quality of their compensatory tracking was on the average 10% higher, the number of errors of their porsuit tracking was 1.8 times lower, and the time of visual signal detection was 2.4 times shorter as compared to the placebo controls.

Adaptation, Physiological↗

PubMedDate not supplied

Development and use of an animal model for investigations on rotator cuff disease.

Although both intrinsic and extrinsic factors have been implicated in the cause of rotator cuff disease, previous studies have not been designed to test hypotheses of this disease, partly because of the lack of an appropriate animal model. Thirty-three animals were evaluated according to a 34 item checklist of criteria to determine their appropriateness as an animal model for investigations on the rotator cuff. Only the rat shoulder satisfactorily fulfilled all criteria, with a prominent supraspinatus tendon passing under an enclosed arch. Once the rat was identified, 36 rats were randomized to three experimental groups. One group (n = 12) was treated with an intratendinous injection of bacterial collagenase simulating an acute intrinsic injury, another group (n = 12) was treated with an acromial alteration to reduce the subacromial space simulating an external compression, and the third group (n = 12) was treated with a combination of both modifications. Significant increases in cellularity, number of fibroblasts, and collagen disorganization were seen in all experimental tendons compared with a contralateral control group. Semiquantitative grading of histologic sections revealed marked changes in all groups at 4 and 8 weeks. Injuries appeared to be healing at 12 weeks except in the combination group, which seemed to demonstrate persistent alterations. This study supports the rat as an appropriate model for investigating rotator cuff disease. In addition, this study demonstrates that both intrinsic and extrinsic alterations can induce changes in the supraspinatus tendon, which may have similarities to human tendon disease.

Animals↗

PubMed1990

Reproduction in the space environment: Part I. Animal reproductive studies.

Mankind's exploration and colonization of the frontier of space will ultimately depend on men's and women's ability to live, work, and reproduce in the space environment. This paper reviews animal studies, from microorganisms to mammals, done in space or under space-simulated conditions, which identify some of the key areas which might interfere with human reproductive physiology and/or embryonic development. Those space environmental factors which impacted almost all species included: microgravity, artificial gravity, radiation, and closed life support systems. These factors may act independently and in combination to produce their effects. To date, there have been no studies which have looked at the entire process of reproduction in any animal species. This type of investigation will be critical in understanding and preventing the problems which will affect human reproduction. Part II will discuss these problems directly as they relate to human physiology.

Animals↗

PubMed2001

Quantification of solute entry into cochlear perilymph through the round window membrane.

The administration of drugs to the inner ear via the round window membrane is becoming more widely used for both clinical and experimental purposes. The actual drug levels achieved in different regions of the inner ear by this method have not been established. The present study has made use of simulations of solute movements in the cochlear fluids to describe the distribution of a marker solute in the guinea pig cochlear fluid spaces. Simulation parameters were derived from experimental measurements using a marker ion, trimethylphenylammonium (TMPA). The distribution of this ion in the cochlea was monitored without volume disturbance using TMPA-selective microelectrodes sealed into the first and second turns of scala tympani (ST). TMPA was applied to perilymph by irrigation of the intact round window membrane with 2 mM solution. At the end of a 90 min application period, TMPA in the first turn, 1.4 mm from the base of ST, reached an average concentration of 330 microM (standard deviation (S.D.) 147 microM, n = 8). TMPA in the second turn, 7.5 mm from the base of ST reached a concentration of 15 microM (S.D. 33 microM, n = 5). The measured time courses of TMPA concentration change were interpreted using the Washington University Cochlear Fluids Simulator (V 1.4), a public-domain program available on the internet at http ://oto.wustl.edu/cochlea/. Simulations with parameters producing concentration time courses comparable to those measured were: (1) round window permeability: 1.9 x 10(-80 cm/s; (2) ST clearance half-time: 60 min; (3) longitudinal perilymph flow rate: 4.4 nl/min, directed from base to apex. Solute concentrations in apical regions of the cochlea were found to be determined primarily by the rate at which the solute diffuses, balanced by the rate of clearance of the solute from perilymph. Longitudinal perilymph flow was not an important factor in solute distribution unless the bony otic capsule was perforated, which rapidly caused substantial changes to solute distribution. This study demonstrates the basic processes by which substances are distributed in the cochlea and provides a foundation to understand how other applied substances will be distributed in the ear.

Animals↗