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At least 163 records · Page 9

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NASA NTRS1990

Assessment of internal contamination problems associated with bioregenerative air/water purification systems

The emphasis is to characterize the mechanisms of bioregenerative revitalization of air and water as well as to assess the possible risks associated with such a system in a closed environment. Marsh and aquatic plants are utilized for purposes of wastewater treatment as well as possible desalinization and demineralization. Foliage plants are also being screened for their ability to remove toxic organics from ambient air. Preliminary test results indicate that treated wastewater is typically of potable quality with numbers of pathogens such as Salmonella and Shigella significantly reduced by the artificial marsh system. Microbiological analyses of ambient air indicate the presence of bacilli as well as thermophilic actinomycetes.

Johnson, Anne H.↗

NASA NTRS1990

A study of murine bone marrow cells cultured in bioreactors which create an environment which simulated microgravity

Previous research indicated that mouse bone marrow cells could be grown in conditions of simulated microgravity. This environment was created in rotating bioreactor vessels. On three attempts mouse cells were grown successfully in the vessels. The cells reached a stage where the concentrations were doubling daily. Phenotypic analysis using a panel of monoclonal antibodies indicated that the cell were hematopoietic pluripotent stem cells. One unsuccessful attempt was made to reestablish the immune system in immunocompromised mice using these cells. Since last summer, several unsuccessful attempts were made to duplicate these results. It was determined by electron microscopy that the cells successfully grown in 1989 contained virus particles. It was suggested that these virally parasitized cells had been immortalized. The work of this summer is a continuation of efforts to grow mouse bone marrow in these vessels. A number of variations of the protocol were introduced. Certified pathogen free mice were used in the repeat experiments. In some attempts the medium of last summer was used; in others Dexture Culture Medium containing Iscove's Medium supplemented with 20 percent horse serum and 10-6 M hydrocortisone. Efforts this summer were directed solely to repeating the work of last summer. Plans were made for investigations if stem cells were isolated. Immortalization of the undifferentiated stem cell would be attempted by transfection with an oncogenic vector. Selective differentiation would be induced in the stem cell line by growing it with known growth factors and immune response modulators. Interest is in identifying any surface antigens unique to stem cells that would help in their characterization. Another goal was to search for markers on stem cells that would distinguish them from stem cells committed to a particular lineage. If the undifferentiated hematopoietic stem cell was obtained, the pathways that would terminally convert it to myeloid, lyphoid, erythroid, or other cell lines would be studied. Transfection with a known gene would be attempted and then conversion to a terminally identifiable cell.

Lawless, Brother Desales↗

NASA NTRS1991

Fiber optic-based biosensor

The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

Ligler, Frances S.↗

NASA NTRS1992

Microbiological challenges of space habitation

The effects of space flight on the growth and pathogenicity of microorganisms and on the human immune response are reviewed giving attention to the implications for spacecraft design. The major sources of microbes within space habitats on long-duration missions are listed including food, crewmembers, and payloads. Many of the microorganisms are shown to be airborne suggesting that effective air-filtration techniques are required for the designs of the Space Station and other vehicles. It is shown that microbial growth rates generally increase during space flight, and space flight is thought to attenuate the human immune response. Some beneficial roles for microbes are identified demonstrating the need for careful control, application, and monitoring of microorganisms in the long-duration spaceflight environment.

Pierson, D. L.↗

NASA NTRS1992

Long-term lunar stations: Some ecological considerations

A major factor for long-term success of a lunar station is the ability to keep an agroecosystem functioning at a desirable, stable steady-state with ecological stability and reliability. Design for a long-lived extraterrestrial manned station must take into account interactions among its subsystems to insure that overall functionality is enhanced (or at least not compromised). Physical isolation of feed production, human living areas, recycling, and other systems may be straightforward, however, microbiological isolation will be very difficult. While it is possible to eliminate plant-associated microbiological communities by growing the plants asepticallly, it is not practical to keep plants germ-free on a large scale if humans are working with them. Ecological theory strongly suggests that some kinds of communities or organisms effectively increase the stability of ecosystems and will protect the plants from potential pathogens. A carefully designed and maintained (lunar-derived) soil can provide a variety of habitats for effective microbial buffers while adding structure to the agroecosystem. A soil can also increase ecosystem reliability through buffering otherwise large element and compound fluctuations (of nutrients, wastes, etc.) as well as buffering temperature level and atmosphere composition. We are doing experiments in ecological dynamics and attempting to extend the relevant theories.

Maguire, Bassett, Jr.↗

NASA NTRS1992

Microbiology operations and facilities aboard restructured Space Station Freedom

With the restructure and funding changes for Space Station Freedom, the Environmental Health System (EHS)/Microbiology Subsystem revised its scheduling and operational requirements for component hardware. The function of the Microbiology Subsystem is to monitor the environmental quality of air, water, and internal surfaces and, in part, crew health on board Space Station. Its critical role shall be the identification of microbial contaminants in the environment that may cause system degradation, produce unsanitary or pathogenic conditions, or reduce crew and mission effectiveness. EHS/Microbiology operations and equipment shall be introduced in concert with a phased assembly sequence, from Man Tended Capability (MTC) through Permanently Manned Capability (PMC). Effective Microbiology operations and subsystem components will assure a safe, habitable, and useful spacecraft environment for life sciences research and long-term manned exploration.

Cioletti, Louis A.↗

NASA NTRS1992

Altered immunological response in mice subjected to stress and exposed to fungal spores

Space flight and related factors such as stress appear to have an adverse effect on astronauts' immune systems. The presence of potentially pathogenic microbes including several genera of fungi reported from spacecraft environment may be a cause of concern in such situations. In order to study the role of such organisms in causing opportunistic or allergic diseases in crewmembers, we have tried to develop an animal model. BALB/c mice were suspended upside down for varying periods of time to induce stress, and their lymphocyte functions were evaluated. These studies indicate that the stress resulted in lowered mitogen induced lymphocyte stimulation as represented by 3H-thymidine uptake. We have also studied the ability of these animals to respond to Aspergillus fumigatus spores. The results of the study clearly demonstrate a definite down-regulation in T-cell proliferation and a higher incidence of infection with A. fumigatus.

Kurup, Viswanath P.↗

NASA NTRS1992

Inactivation of a model coliphage virus in water by iodine

Until now, NASA's space water reuse research program has not considered the transport of water-borne infectious enteric viruses; however, viral diseases probably are a signifficant concern in long-duration space missions. To simplify monitoring and prediction of pathogen distribution, model indicator strains historically have been used. In this research, the male specific RNA coliphage MS-2 is used as a model of enteric viruses due to their similar size and biochemical composition. Inactivation of some water-borne enteric viruses by iodine has previously been characterized. In this paper, iodine inactivation of the model coliphage MS-2 in buffered water is compared with earlier bench-scale disinfection survival data and with survival in iodinated simulated shower water used in a test water recycling system.

Brion, Gail M.↗

NASA NTRS1994

Microbial biofilm formation and its consequences for the CELSS program

A major goal of the Controlled Ecology Life Support System (CELSS) program is to provide reliable and efficient life support systems for long-duration space flights. A principal focus of the program is on the growth of higher plants in growth chambers. These crops should be grown without the risk of damage from microbial contamination. While it is unlikely that plant pathogens will pose a risk, there are serious hazards associated with microorganisms carried in the nutrient delivery systems and in the atmosphere of the growth chamber. Our experience in surface microbiology showed that colonization of surfaces with microorganisms is extremely rapid even when the inoculum is small. After initial colonization extensive biofilms accumulate on moist surfaces. These microbial films metabolize actively and slough off continuously to the air and water. During plant growth in the CELSS program, microbial biofilms have the potential to foul sensors and to plug nutrient delivery systems. In addition both metabolic products of microbial growth and degradation products of materials being considered for use as nutrient reservoirs and for delivery are likely sources of chemicals known to adversly affect plant growth.

Mitchell, R.↗

NASA NTRS1994

Continuous monitoring of bacterial attachment

A major concern with the Space Station Freedom (SSF) water supply system is the control of longterm microbial contamination and biofilm development in the water storage and distribution systems. These biofilms have the potential for harboring pathogens as well as microbial strains containing resistance factors that could negatively influence crew health. The proposed means for disinfecting the water system on SSF (iodine) may encourage the selection of resistant strains. In fact, biofilm bacteria were observed in water lines from the Space Shuttle Columbia (OV-102); therefore, an alternative remediation method is required to disinfect spacecraft water lines. A thorough understanding of colonization events and the physiological parameters that will influence bacteria adhesion is required. The limiting factor for development of this technology is the ability to continuously monitor adhesion events and the effects of biocides on sessile bacteria. Methods were developed to allow bacterial adhesion and subsequent biocidal treatment to be monitored continuously. This technique couples automated image analysis with a continuous flow of a bacterial suspension through an optical flow cell. A strain of Pseudomonas cepacia isolated from the water supply of the Space Shuttle Discovery (OV-103) during STS-39 was grown in a nitrogen-limited continuous culture. This culture was challenged continuously with iodine during growth, and the adhesion characteristics of this strain was measure with regard to flow rate. Various biocides (ozone, hypochlorite, and iodine) were added to the flow stream to evaluate how well each chemical removed the bacteria. After biocide treatment, a fresh bacterial suspension was introduced into the flow cell, and the attachment rate was evaluated on the previously treated surface. This secondary fouling was again treated with biocide to determine the efficacy of multiple batch chemical treatments in removing biofilm.

Koeing, D. W.↗

NASA NTRS1994

Extended duration orbiter medical project Microbial Air Sampler (STS-50/USML-1)

The Microbial Air Sampler was used on mission days 1, 7, and 13 in the Spacelab during STS-50/USML-1. Microbial air samples were collected using two types of media strips containing agar (Rose Bengal for yeast and molds, TSA for bacteria). The bacterial level found on day 1 was lower than experienced on previous Spacelab missions. A high level of fungi was present on day 1, however subsequent samples on days 7 and 13 did not indicate fungal growth. Bacterial growth was also minimized in this microgravity environment as the mission progressed. No pathogenic microorganisms were isolated, and the health risk from airborne microbes was minimal throughout the mission.

Pierson, Duane L.↗

NASA NTRS1993

Immune changes in humans concomitant with space flights of up to 10 days duration

The time relation of various classes of in-flight human physiological changes is illustrated. Certain problems, such as neurovestibular, fluid, and electrolyte imbalances tend to occur early in a flight, followed by stabilization at some microgravity equilibrium level. Cardiovascular dysfunctions and erythrocyte mass losses appear to follow a similar pattern, although the significant changes occur later in flight. Bone and calcium changes and radiation effects are thought to progressively worsen with time, whereas the time course of immune change is yet to be fully understood. Significant immunologic changes in cosmonauts and astronauts during and after space flight have been documented as have microbiological changes. Thus, space flight can be expected to effect a blunting of the human cellular immune mechanism concomitant with a relative increase in potentially pathogenic microorganisms. This combination would seem to increase the probability of infectious disease events in flight.

Taylor, Gerald R.↗

NASA NTRS1994

A rose by any other name: Certification seen as process rather than content

Green (1990) believes that the two main factors safeguarding flying from human error are both related to certification and regulation. First is the increasingly proceduralized nature of flying whereby as much as possible is reduced to a rule-based activity. Second is the emphasis placed upon training and competency checking of aircrew in simulators and in the air, both generally and for all particular types of aircraft flown. This leaves, believes Green, other human factors that are relatively unaddressed as yet and which can give rise to human reliability problems. These include: hardware factors and especially pilot/co-pilot relationships; and system factors including fatigue and cost/safety trade-offs. He also, importantly, identifies problems with the integration of the 'electronic crew member' following increased automation. Human reliability failures with artificial intelligence and automation, due to over-reliance on the system fail-safe mechanisms, or to operator under- confidence in the integrity or self-regulating capacity of the system, or to out-of-loop effects, are widely accepted as being due to deficiencies in plant design, planning, management and maintenance more than to 'operator error' - Reason's (1990) latent error or organization pathogens argument. Reliability failures in complex systems are well enough documented to give cause for concern and at least promote a debate on the merits of a full certification program. The purpose of this short paper is to seek out and explore what is valuable in certification, at the least to show that the benefits outweigh the disadvantages and at best to identify positive outcomes perhaps not obtainable in other ways. On both sides of the debate on certification there is general agreement on the need for a better human factors perspective and effort in complex aviation systems design. What is at issue is how this is to be promoted. It is incumbent upon opponents of certification to say how else such promotion be enabled. This is an exploratory and philosophical review, not a focused and specific one, and it will draw upon much that is not firmly in the domain of complex aviation systems.

Wilson, John R.↗

NASA NTRS1994

Anatomy of a system accident: The crash of Avianca Flight 052

On January 25, 1990, Avianca Flight 052 crashed after running out of fuel following a missed approach to New York's John F. Kennedy Airport. Weather was poor on the East Coast of the United States that day, and the flight had experienced several holding patterns enroute from Medellin, Colombia, to New York. The accident is analyzed in terms of Helmreich and Foushee's (1993) model of crew performance and Reason's (1990) model of latent pathogens in system operations.

Helmreich, Robert L.↗

NASA NTRS1993

Preflight and postflight microbiological results from 25 space shuttle crews

Clinical-microbiological investigations are an important aspect of the crew health stabilization program. To ensure that space crews have neither active nor latent infections, clinical specimens, including throat and nasal swabs and urine samples, are collected at 10 days (L-10) and 2days (L-2) before launch, and immediately after landing (L+0). All samples are examined for the presence of bacteria and fungi. In addition, fecal samples are collected at L-10 and examined for bacteria, fungi and parasites. This paper describes clinical-microbiological findings from 144 astronauts participating in 25 Space Shuttle missions spanning Space Transportation System (STS)-26 to STS-50. The spectrum of microbiological findings from the specimens included 25 bacterial and 11 fungal species. Among the bacteria isolated most frequently were Staphylococcus aureus, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, Proteus mirabilis and Streptococcus agalactiae. Candida albicans was the most frequently isolated fungal pathogen.

Pierson, Duane L.↗

NASA NTRS1994

Life Sciences and Space Research 25 (3): Natural and Artifical Ecosystems; Meeting F4 of the COSPAR Plenary Meeting, 29th, Washington, DC, Aug. 28-Sep. 5, 1992

Bioregenerative life support systems will be an essential part of long duration manned space flight. Studies have been made of various components of these closed ecological systems. these studies have included those spaceborne experiments on Spacelab and Mir, as well as ground-based simulations. The effects of reduced gravity include alterations in food crop and other plant growth and vigor. Systems have also been designed and tested to provide a balanced regenerative system that recycles airborne and other wastes while providing nutrients and other input for future cycles. Hydroponic cultivation must include control of pathogens. All closed systems require sensing and automatic control.

Macelroy, R. D.↗

NASA NTRS1995

Portable Immune-Assessment System

Portable immune-assessment system developed for use in rapidly identifying infections or contaminated environment. System combines few specific fluorescent reagents for identifying immune-cell dysfunction, toxic substances, buildup of microbial antigens or microbial growth, and potential identification of pathogenic microorganisms using fluorescent microplate reader linked to laptop computer. By using few specific dyes for cell metabolism, DNA/RNA conjugation, specific enzyme activity, or cell constituents, one makes immediate, onsite determination of person's health or of contamination of environment.

Pierson, Duane L.↗

NASA NTRS1995

Predatory Microorganisms Would Help Reclaim Water

Wastewater-reclamation systems of proposed type use predatory, nonpathogenic microorganisms to consume pathogenic microorganisms. Unlike some other wastewater-reclamation systems, these systems do not require use of toxic chemicals, intense heat, or ionizing radiation (conductivity rays or ultraviolet) to destroy microorganisms.

Benjaminson, Morris A.↗