Engineering topics

Pierson, D. L.

Publications and source records attributed to Pierson, D. L..

At least 19 records

NASA NTRS2014

The Impact of Apollo-Era Microbiology on Human Space Flight

The microbiota of crewmembers and the spacecraft environment contributes significant risk to crew health during space flight missions. NASA reduces microbial risk with various mitigation methods that originated during the Apollo Program and continued to evolve through subsequent programs: Skylab, Shuttle, and International Space Station (ISS). A quarantine of the crew and lunar surface samples, within the Lunar Receiving Laboratory following return from the Moon, was used to prevent contamination with unknown extraterrestrial organisms. The quarantine durations for the crew and lunar samples were 21 days and 50 days, respectively. A series of infections among Apollo crewmembers resulted in a quarantine before launch to limit exposure to infectious organisms. This Health Stabilization Program isolated the crew for 21 days before flight and was effective in reducing crew illness. After the program developed water recovery hardware for Apollo spacecraft, the 1967 National Academy of Science Space Science Board recommended the monitoring of potable water. NASA implemented acceptability limits of 10 colony forming units (CFU) per mL and the absence of viable E. coli, anaerobes, yeasts, and molds in three separate 150 mL aliquots. Microbiological investigations of the crew and spacecraft environment were conducted during the Apollo program, including the Apollo-Soyuz Test Project and Skylab. Subsequent space programs implemented microbial screening of the crew for pathogens and acceptability limits on spacecraft surfaces and air. Microbiology risk mitigation methods have evolved since the Apollo program. NASA cancelled the quarantine of the crew after return from the lunar surface, reduced the duration of the Health Stabilization Program; and implemented acceptability limits for spacecraft surfaces and air. While microbial risks were not a main focus of the early Mercury and Gemini programs, the extended duration of Apollo flights resulted in the increased scrutiny of impact of the space flight environment on crew health. The lessons learned during that era of space flight continue to impact microbiology risk mitigation in space programs today.

Elliott, T. F↗

NASA NTRS2013

From Space to the Patient: A New Cytokine Release Assay to Monitor the Immune Status of HIV Infected Patients and Sepsis Patients

Monitoring of humans either in the healthy men under extreme environmental stress like space flight, in human immunodeficiency virus (HIV) infected patients or in sepsis is of critical importance with regard to the timing of adequate therapeutic (counter-)measures. The in vivo skin delayed-type hypersensitivity test (DTH) served for many years as a tool to evaluate cell mediated immunity. However, this standardised in vivo test was removed from the market in 2002 due to the risk of antigen stabilization. To the best of our knowledge an alternative test as monitoring tool to determine cell mediated immunity is not available so far. For this purpose we tested a new alternative assay using elements of the skin DTH which is based on an ex vivo cytokine release from whole blood and asked if it is suitable and applicable to monitor immune changes in HIV infected patients and in patients with septic shock.

Kaufmann, I.↗

NASA NTRS2012

Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment

The determination of risk from infectious disease during spaceflight missions is composed of several factors including both the concentration and characteristics of the microorganisms to which the crew are exposed. Thus, having a good understanding of the microbial ecology aboard spacecraft provides the necessary information to mitigate health risks to the crew. While preventive measures are taken to minimize the presence of pathogens on spacecraft, medically significant organisms have been isolated from both the Mir and International Space Station (ISS). Historically, the method for isolation and identification of microorganisms from spacecraft environmental samples depended upon their growth on culture media. Unfortunately, only a fraction of the organisms may grow on a specific culture medium, potentially omitting those microorganisms whose nutritional and physical requirements for growth are not met. To address this bias in our understanding of the ISS environment, the Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment was designed to investigate and develop monitoring technology to provide better microbial characterization. For the SWAB flight experiment, we hypothesized that environmental analysis using non-culture-based technologies would reveal microorganisms, allergens, and microbial toxins not previously reported in spacecraft, allowing for a more complete health assessment. Key findings during this experiment included: a) Generally, advanced molecular techniques were able to reveal a few organisms not recovered using culture-based methods; however, there is no indication that current monitoring is "missing" any medically significant bacteria or fungi. b) Molecular techniques have tremendous potential for microbial monitoring, however, sample preparation and data analysis present challenges for spaceflight hardware. c) Analytical results indicate that some molecular techniques, such as denaturing gradient gel electrophoresis (DGGE), can be much less sensitive than culture-based methods. d) More sensitive molecular techniques, such as quantitative polymerase chain reaction (QPCR), were able to identify viral DNA from ISS environments, suggesting potential transfer of the organism between crewmembers. In addition, the hardware selected for this experiment represented advances for next-generation sample collection. The advanced nature of this collection hardware was noted, when the Sartorius MD8 Air Port air sampler from the SWAB experiment remained on board ISS at the request of JAXA investigators, who intend to use it in completion of their microbial ecology experiment.

Castro, V. A.↗

NASA NTRS2012

Next Generation Microbiology Requirements

As humans continue to explore deep into space, microorganisms will travel with them. The primary means to mitigate the risk of infectious disease are a combination of prudent spacecraft design and rigorous operational controls. The effectiveness of these methods are evaluated by microbiological monitoring of spacecraft, food, water, and the crew that is performed preflight, in-flight, and post-flight. Current NASA requirements associated with microbiological monitoring are based on culture-based methodology where microorganisms are grown on a semi-solid growth medium and enumerated. Subsequent identification of the organisms requires specialized labor and large equipment, which historically has been performed on Earth. Requirements that rely strictly on culture-based units limit the use of non-culture based monitoring technology. Specifically, the culture-based "measurement criteria" are Colony Forming Units (CFU, representing the growth of one microorganism at a single location on the agar medium) per a given volume, area, or sample size. As the CFU unit by definition is culture-based, these requirements limit alternative technologies for spaceflight applications. As spaceflight missions such as those to Mars extend further into space, culture-based technology will become difficult to implement due to the (a) limited shelf life of the culture media, (b) mass/volume necessary to carry these consumables, and (c) problems associated with the production of biohazardous material in the habitable volume of the spacecraft. In addition, an extensive amount of new knowledge has been obtained during the Space Shuttle, NASA-Mir, and International Space Station Programs, which gave direction for new or modified microbial control requirements for vehicle design and mission operations. The goal of this task is to develop and recommend a new set of requirements for vehicle design and mission operations, including microbiological monitoring, based upon "lessons learned" and new technology. During 2011, this study focused on evaluating potable water requirements by assembling a forum of internal and external experts from NASA, other federal agencies, and academia. Key findings from this forum included: (1) Preventive design and operational strategies should be stringent and the primary focus of NASA's mitigation efforts, as they are cost effective and can be attained with conventional technology. (2) Microbial monitoring hardware should be simple and must be able to measure the viability of microorganisms in a sample. Multiple monitoring technologies can be utilized as long as at the microorganisms being identified can also be confirmed as viable. (3) Evidence showing alterations in the crew immune function and microbial virulence complicates risk assessments and creates the need for very conservative requirements. (4) One key source of infectious agents will always be the crew, and appropriate preventative measures should be taken preflight. (5) Water systems should be thoroughly disinfected (sterilized if possible) preflight and retain a residual biocide throughout the mission. Future forums will cover requirements for other types of samples, specifically spaceflight food and environmental samples, such as vehicle air and vehicle and cargo surfaces. An interim report on the potable water forum has been delivered to the Human Research Program with a final report on the recommendations for all sample types being delivered in September 2013.

Ott, C. M.↗

NASA NTRS2011

NASA 14 Day Undersea Missions: A Short-Duration Spaceflight Analog for Immune System Dysregulation?

This poster paper reviews the use of 14 day undersea missions as a possible analog for short duration spaceflight for the study of immune system dysregulation. Sixteen subjects from the the NASA Extreme Enviro nment Mission Operations (NEEMO) 12, 13 and 14 missions were studied for immune system dysregulation. The assays that are presented in this poster are the Virleukocyte subsets, the T Cell functions, and the intracellular/secreted cytokine profiles. Other assays were performed, but are not included in this presntation.

Crucian, B. E.↗

NASA NTRS2011

Vitamin D Supplementation and Immune Response to Antarctic Winter

Maintaining vitamin D status without sunlight exposure is difficult without supplementation. This study was designed to better understand interrelationships between periodic cholecalciferol(vitamin D3) supplementation and immune function in Antarctic workers. The effect of 2 oral dosing regimens of vitamin D3 supplementation on vitamin D status and markers of immune function were evaluated in people in Antarctica with no ultraviolet light exposure for 6 mo. Participants were given a 2,000-IU (50 g) daily (n=15) or 10,000-IU (250 g) weekly (n=14) vitamin D3 supplement for 6 mo during a winter in Antarctica. Biological samples were collected at baseline and at 3 and 6 mo. Vitamin D intake, markers of vitamin D and bone metabolism, and latent virus reactivation were determined. After 6 mo the mean (SD) serum 25-hydroxyvitamin D3 concentration increased from 56 plus or minus 17 to 79 plus or minus 16 nmol/L and 52 plus or minus 10 to 69 plus or minus 9 nmol/L in the 2,000-IU/d and 10,000-IU/wk groups (main effect over time P less than 0.001). Participants with a greater BMI (participant BMI range = 19-43 grams per square meter) had a smaller increase in 25-hydroxyvitamin D3 after 6 mo supplementation (P less than 0.05). Participants with high serum cortisoland higher serum 25-hydroxyvitamin D3 were less likely to shed Epstein-Barr virus in saliva (P less than 0.05). The doses given raised vitamin D status in participants not exposed to sunlight for 6 mo, and the efficacy was influenced by baseline vitamin D status and BMI. The data also provide evidence that vitamin D, interacting with stress, can reduce risk of latent virus reactivation during the winter in Antarctica.

Zwart, S. R.↗

NASA NTRS2011

Intake of Fish and Omega-3 (n-3) Fatty Acids: Effect on Humans During Actual and Simulated Weightlessness

Space flight has many negative effects on human physiology, including bone and muscle loss. Bone and muscle are two systems that are positively affected by dietary intake of fish and n-3 fatty acids. The mechanism is likely to be related to inhibition by n-3 fatty acids of inflammatory cytokines (such as TNF) and thus inhibition of downstream NF-kB activation. We have documented this effect in a 3-dimensional cell culture model, where NF-kB activation in osteoclasts was inhibited by eicosapentaenoic acid, an n-3 fatty acid. We have also indentified that NF-kB activation in peripheral blood mononuclear cells of Space Shuttle crews. We found that after Shuttle flights of ~2 wk, expression of the protein p65 (evidence of NF-kB activation) was increased at landing (P less than 0.001). When evaluating the effects of n-3 fatty acid intake on bone breakdown after 60 d of bed rest (a weightlessness analog). We found that after 60 d of bed rest, greater intake of n-3 fatty acids was associated with less N-telopeptide excretion (Pearson r = -0.62, P less than 0.05). We also evaluated the relationship of fish intake and bone loss in astronauts after 4 to 6 mo missions on the International Space Station. Higher consumption of fish during flight was associated with higher bone mineral density (Pearson r = 0.46, P less than 0.05). Together, these findings provide evidence of the cellular mechanism by which n-3 fatty acids can inhibit bone loss, and preliminary human evidence of the potential for n-3 fatty acids to counteract bone loss associated with space flight. This study was supported by the NASA Human Research Program.

Smith, S. M.↗

NASA NTRS2011

The ESA-NASA 'CHOICE' Study: Winterover at Concordia Station, Interior Antarctica, as an Analog for Spaceflight-Associated Immune Dysregu1ation

For ground-based space physiological research, the choice of analog must carefully match the system of interest. Antarctica winter-over at the European Concordia Station is potentially a ground-analog for spaceflight-associated immune dysregulation (SAID). Concordia missions consist of prolonged durations in an extreme/dangerous environment, station-based habitation, isolation, disrupted circadian rhythms and international crews. The ESA-NASA CHOICE study assess innate and adaptive immunity, viral reactivataion and stress factors during Concordia winter-over deployment. To date, not all samples have been analyzed. Here, only data will be preliminary presented for those parameters where sample/data analysis is completed (i.e., Leukocyte subsets, T cell function, and intracellular/secreted cytokine profiles.)

Crucian, Brian E,↗

NASA NTRS2011

Latent Virus Reactivation in Space Shuttle Astronauts

Latent virus reactivation was measured in 17 astronauts (16 male and 1 female) before, during, and after short-duration Space Shuttle missions. Blood, urine, and saliva samples were collected 2-4 months before launch, 10 days before launch (L-10), 2-3 hours after landing (R+0), 3 days after landing (R+14), and 120 days after landing (R+120). Epstein-Barr virus (EBV) DNA was measured in these samples by quantitative polymerase chain reaction. Varicella-zoster virus (VZV) DNA was measured in the 381 saliva samples and cytomegalovirus (CMV) DNA in the 66 urine samples collected from these subjects. Fourteen astronauts shed EBV DNA in 21% of their saliva samples before, during, and after flight, and 7 astronauts shed VZV in 7.4% of their samples during and after flight. It was interesting that shedding of both EBV and VZV increased during the flight phase relative to before or after flight. In the case of CMV, 32% of urine samples from 8 subjects contained DNA of this virus. In normal healthy control subjects, EBV shedding was found in 3% and VZV and CMV were found in less than 1% of the samples. The circadian rhythm of salivary cortisol measured before, during, and after space flight did not show any significant difference between flight phases. These data show that increased reactivation of latent herpes viruses may be associated with decreased immune system function, which has been reported in earlier studies as well as in these same subjects (data not reported here).

Mehta, S. K.↗

NASA NTRS2011

Immune System Dysregulation and Latent Herpesvirus Reactivation During Winterover at Concordia Station, Dome C, Antarctica

Immune system dysregulation occurs during spaceflight and consists of altered peripheral leukocyte distribution, reductions in immunocyte function and altered cytokine production profiles. Causes may include stress, confinement, isolation, and disrupted circadian rhythms. All of these factors may be replicated to some degree in terrestrial environments. NASA is currently evaluating the potential for a ground-based analog for immune dysregulation, which would have utility for mechanistic investigations and countermeasures evaluation. For ground-based space physiology research, the choice of terrestrial analog must carefully match the system of interest. Antarctica winter-over, consisting of prolonged durations in an extreme/dangerous environment, station-based habitation, isolation and disrupted circadian rhythms, is potentially a good ground-analog for spaceflight-associated immune dysregulation. Of all Antarctica bases, the French-Italian Concordia Station, may be the most appropriate to replicate spaceflight/exploration conditions. Concordia is an interior base located in harsh environmental conditions, and has been constructed to house small, international crews in a station-environment similar to what should be experienced by deep space astronauts. The ESA-NASA CHOICE study assessed innate and adaptive immunity, viral reactivation and stress factors during Concordia winterover deployment. The study was conducted over two winterover missions in 2009 and 2010. Final study data from NASA participation in these missions will be presented.

Crucian, B. E.↗

NASA NTRS2010

NASA 14 Day Undersea Missions: A Short-Duration Spaceflight Analog for Immune System Dysregulation

BACKGROUND Spaceflight-associated immune dysregulation (SAID) occurs during spaceflight and may represent specific clinical risks for exploration-class missions. An appropriate ground analog for spaceflight-associated immune dysregulation would offer a platform for ground-evaluation of various potential countermeasures. This study evaluated the NASA Undersea Mission Operations ( NEEMO ), consisting of 14 day undersea deployment at the Aquarius station, as an analog for SAID. Sixteen Aquanauts from missions NEEMO-12, 13 and 14 participated in the study. RESULTS Mid-mission alterations leukocyte distribution occurred, including granulocytosis and elevations in central-memory CD8+ T-cells. General T cell function was reduced during NEEMO missions in roughly 50% of subjects. Secreted cytokines profiles were evaluated following whole blood stimulation with CD3/CD28 (T cells) or LPS (monocytes). T cell production of IFNg, IL-5, IL-10, IL-2, TNFa and IL-6 were all reduced before and during the mission. Conversely, monocyte production of TNFa, IL-10, IL-6, IL-1b and IL-8 were elevated during mission, moreso at the MD-14 timepoint. Antibodies to Epstein-Barr virus (EBV) viral capsid antigen and early antigen were increased in approximately 40% of the subjects. Changes in EBV tetramer-positive CD8+ T-cells exhibited a variable pattern. Antibodies against Cytomegalovirus (CMV) were marginally increased during the mission. Herpesvirus reactivation was determined by PCR. EBV viral load was generally elevated at L-6. Higher levels of salivary EBV were found during the NEEMO mission than before and after as well as than the healthy controls. No VZV or CMV was found in any pre, during and after NEEMO mission or control samples. Plasma cortisol was elevated at L-6. CONCLUSION Unfortunately, L-6 may be too near to mission start to be an appropriate baseline measurement. The general immune changes in leukocyte distribution, T cell function, cytokine production, virus specific immunity and viral reactivation are similar to those observed during or following spaceflight. The NEEMO platform may thus have utility for short-duration, ground-based spaceflight-immune research, such as investigations of mechanism or countermeasures validation.

Crucian, B. E.↗

NASA NTRS2009

Microbial Risk Assessment

Historically, microbiological spaceflight requirements have been established in a subjective manner based upon expert opinion of both environmental and clinical monitoring results and the incidence of disease. The limited amount of data, especially from long-duration missions, has created very conservative requirements based primarily on the concentration of microorganisms. Periodic reevaluations of new data from later missions have allowed some relaxation of these stringent requirements. However, the requirements remain very conservative and subjective in nature, and the risk of crew illness due to infectious microorganisms is not well defined. The use of modeling techniques for microbial risk has been applied in the food and potable water industries and has exceptional potential for spaceflight applications. From a productivity standpoint, this type of modeling can (1) decrease unnecessary costs and resource usage and (2) prevent inadequate or inappropriate data for health assessment. In addition, a quantitative model has several advantages for risk management and communication. By identifying the variable components of the model and the knowledge associated with each component, this type of modeling can: (1) Systematically identify and close knowledge gaps, (2) Systematically identify acceptable and unacceptable risks, (3) Improve communication with stakeholders as to the reasons for resource use, and (4) Facilitate external scientific approval of the NASA requirements. The modeling of microbial risk involves the evaluation of several key factors including hazard identification, crew exposure assessment, dose-response assessment, and risk characterization. Many of these factors are similar to conditions found on Earth; however, the spaceflight environment is very specialized as the inhabitants live in a small, semi-closed environment that is often dependent on regenerative life support systems. To further complicate modeling efforts, microbial dose-response characteristics may be affected by a potentially dysfunctional crew immune system during a mission. In addition, microbial virulence has been shown to change under certain conditions during spaceflight, further complicating dose-response characterization. An initial study of the applicability of microbial risk assessment techniques was performed using Crew Health Care System (CHeCS) operational data from the International Space Station potable water systems. The risk of infection from potable water was selected as the flight systems and microbial ecology are well defined. This initial study confirmed the feasibility of using microbial risk assessment modeling for spaceflight systems. While no immediate threat was detected, the study identified several medically significant microorganisms that could pose a health risk if uncontrolled. The study also identified several specific knowledge gaps in making a risk assessment and noted that filling these knowledge gaps is essential as the risk estimates may change by orders of magnitude depending on the answers. The current phase of the microbial risk assessment studies focuses on the dose-response relationship of specific infectious agents, focusing on Salmonella enterica Typhimurium, Pseudomonas spp., and Escherichia coli, as their evaluation will provide a better baseline for determining the overall hazard characterization. The organisms were chosen as they either have been isolated on spacecraft or have an identified route of infection during a mission. The characterization will utilize dose-response models selected either from the peer-reviewed literature and/or by using statistical approaches. Development of these modeling and risk assessment techniques will help to optimize flight requirements and to protect the safety, health, and performance of the crew.

Ott, C. M.↗

NASA NTRS2008

Latent Herpes Viral Reactivation in Astronauts

Latent viruses are ubiquitous and reactivate during stressful periods with and without symptoms. Latent herpes virus reactivation is used as a tool to predict changes in the immune status in astronauts and to evaluate associated health risks. Methods: Viral DNA was detected by real time polymerase chain reaction in saliva and urine from astronauts before, during and after short and long-duration space flights. Results and Discussion: EpsteinBarr virus (EBV), cytomegalovirus (CMV), and varicella zoster virus (VZV) reactivated, and viral DNA was shed in saliva (EBV and VZV) or urine (CMV). EBV levels in saliva during flight were 10fold higher than baseline levels. Elevations in EBV specific CD8+ T-cells, viral antibody titers, and specific cytokines were consistent with viral reactivation. Intracellular levels of cytokines were reduced in EBVspecific Tcells. CMV, rarely present in urine of healthy individuals, was shed in urine of 27% of astronauts during all phases of spaceflight. VZV, not found in saliva of asymptomatic individuals, was found in saliva of 50% of astronauts during spaceflight and 35 days after flight. VZV recovered from astronaut saliva was found to be live, infectious virus. DNA sequencing demonstrated that the VZV recovered from astronauts was from the common European strain of VZV. Elevation of stress hormones accompanied viral reactivation indicating involvement of the hypothalmic-pituitary-adrenal and sympathetic adrenal-medullary axes in the mechanism of viral reactivation in astronauts. A study of 53 shingles patients found that all shingles patients shed VZV DNA in their saliva and the VZV levels correlated with the severity of the disease. Lower VZV levels in shingles patients were similar to those observed in astronauts. We proposed a rapid, simple, and cost-effective assay to detect VZV in saliva of patients with suspected shingles. Early detection of VZV infection allows early medical intervention.

Pierson, D. L.↗

NASA NTRS2007

Effect Of Spaceflight On Microbial Gene Expression And Virulence: Preliminary Results From Microbe Payload Flown On-Board STS-115

Human presence in space, whether permanent or temporary, is accompanied by the presence of microbes. However, the extent of microbial changes in response to spaceflight conditions and the corresponding changes to infectious disease risk is unclear. Previous studies have indicated that spaceflight weakens the immune system in humans and animals. In addition, preflight and in-flight monitoring of the International Space Station (ISS) and other spacecraft indicates the presence of opportunistic pathogens and the potential of obligate pathogens. Altered antibiotic resistance of microbes in flight has also been shown. As astronauts and cosmonauts live for longer periods in a closed environment, especially one using recycled water and air, there is an increased risk to crewmembers of infectious disease events occurring in-flight. Therefore, understanding how the space environment affects microorganisms and their disease potential is critically important for spaceflight missions and requires further study. The goal of this flight experiment, operationally called MICROBE, is to utilize three model microbial pathogens, Salmonella typhimurium, Pseudomonas aeruginosa, and Candida albicans to examine the global effects of spaceflight on microbial gene expression and virulence attributes. Specifically, the aims are (1) to perform microarray-mediated gene expression profiling of S. typhimurium, P. aeruginosa, and C. albicans, in response to spaceflight in comparison to ground controls and (2) to determine the effect of spaceflight on the virulence potential of these microorganisms immediately following their return from spaceflight using murine models. The model microorganisms were selected as they have been isolated from preflight or in-flight monitoring, represent different degrees of pathogenic behavior, are well characterized, and have sequenced genomes with available microarrays. In particular, extensive studies of S. typhimurium by the Principal Investigator, Dr. Nickerson, using ground-based analog systems demonstrate important changes in the genotypic, phenotypic, and virulence characteristics of this pathogen resulting from exposure to a flight-like environment (i.e. modeled microgravity).

Wilson, J. W.↗

NASA NTRS2007

A Comprehensive Characterization of Microorganisms and Allergens in Spacecraft Environment

The determination of risk from infectious disease during long-duration missions is composed of several factors including (1) the host#s susceptibility, (2) the host#s exposure to the infectious disease agent, and (3) the concentration of the infectious agent, and (4) the characteristics of the infectious agent. While stringent steps are taken to minimize the transfer of potential pathogens to spacecraft, several medically significant organisms have been isolated from both the Mir and International Space Station (ISS). Historically, the method for isolation and identification of microorganisms from spacecraft environmental samples depended upon their growth on culture media. Unfortunately, only a fraction of the organisms may grow on a culture medium, potentially omitting those microorganisms whose nutritional and physical requirements for growth are not met. Thus, several pathogens may not have been detected, such as Legionella pneumophila, the etiological agent of Legionnaire#s disease. We hypothesize that environmental analysis using non-culture-based technologies will reveal microorganisms, allergens, and microbial toxins not previously reported in spacecraft, allowing for a more complete health assessment. The development of techniques for this flight experiment, operationally named SWAB, has already provided advances in NASA laboratory processes and beneficial information toward human health risk assessment. The first accomplishment of the SWAB experiment was the incorporation of 16S ribosomal DNA sequencing for the identification of bacteria. The use of this molecular technique has increased bacterial speciation of environmental isolates from previous flights three fold compared to conventional methodology. This increased efficiency in bacterial speciation provides a better understanding of the microbial ecology and the potential risk to the crew. Additional SWAB studies focused on the use of molecular-based DNA fingerprinting using repetitive sequencebased polymerase chain reaction (rep-PCR). This technology has allowed contamination tracking of microorganisms between crewmembers and their environment. This study not only demonstrated that ISS has a greater diversity of organisms than originally expected, but also provided insight into possible routes of infection to the crew. Additional ground-based studies used rep-PCR and protein based assays to determine the potential of methicillin resistant Staphylococcus aureus (MRSA) aboard ISS. MRSA has become increasingly common on Earth and pose a treatment problem for infections during flight. While no MRSA have been isolated from ISS to date, the mecA gene product that is responsible for methicillin resistance was isolated in other Staphylococcus species aboard ISS suggesting a potential of MRSA through gene transfer. Using improved sample collection technologies, flight sampling for SWAB was initiated in August 2006 and should continue through spring of 2007. The focus of these flight samples is the collection of DNA for evaluation by Denaturing Gradient Gel Electrophoresis (DGGE). Unlike other techniques, DGGE does not depend on any microbial growth on culture media allowing a more comprehensive assessment of the spacecraft interior. This study should provide insight into the true microbial ecology that is experienced by the crew during flight. This information will lead toward an accurate microbial risk assessment to help set flight requirements to protect the safety, health, and performance of the crew.

Ott, C. M.↗

NASA NTRS2006

The Influence of Microbiology on Spacecraft Design and Controls: A Historical Perspective of the Shuttle and International Space Station Programs

For over 40 years, NASA has been putting humans safely into space in part by minimizing microbial risks to crew members. Success of the program to minimize such risks has resulted from a combination of engineering and design controls as well as active monitoring of the crew, food, water, hardware, and spacecraft interior. The evolution of engineering and design controls is exemplified by the implementation of HEPA filters for air treatment, antimicrobial surface materials, and the disinfection regimen currently used on board the International Space Station. Data from spaceflight missions confirm the effectiveness of current measures; however, fluctuations in microbial concentrations and trends in contamination events suggest the need for continued diligence in monitoring and evaluation as well as further improvements in engineering systems. The knowledge of microbial controls and monitoring from assessments of past missions will be critical in driving the design of future spacecraft.

Castro, Victoria A.↗

NASA NTRS2005

The Evaluation of Methicillin Resistance in Staphylococcus aboard the International Space Station

The International Space Station (ISS) represents a semi-closed environment with a high level of crewmember interaction. As community-acquired methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a health concern in environments with susceptible hosts in close proximity, an evaluation of isolates of clinical and environmental Staphylococcus aureus and coagulase negative Staphylococcus was performed to determine if this trend was also present in astronauts aboard ISS or the space station itself. Rep-PCR fingerprinting analysis of archived ISS isolates confirmed our earlier studies indicating a transfer of S. aureus between crewmembers. In addition, this fingerprinting also indicated a transfer between crewmembers and their environment. While a variety of S. aureus were identified from both the crewmembers and the environment, phenotypic evaluations indicated minimal methicillin resistance. However, positive results for the Penicillin Binding Protein, indicative of the presence of the mecA gene, were detected in multiple isolates of archived Staphylococcus epidermidis and Staphylococcus haemolyticus. Phenotypic analysis of these isolates confirmed their resistance to methicillin. While MRSA has not been isolated aboard ISS, the potential exists for the transfer of the gene, mecA, from coagulase negative environmental Staphylococcus to S. aureus creating MRSA strains. This study suggests the need to expand environmental monitoring aboard long duration exploration spacecraft to include antibiotic resistance profiling.

Ott, C. M.↗

NASA NTRS2005

Epstein-Barr virus shedding by astronauts during space flight

Patterns of Epstein-Barr virus (EBV) reactivation in 32 astronauts and 18 healthy age-matched control subjects were characterized by quantifying EBV shedding. Saliva samples were collected from astronauts before, during, and after 10 space shuttle missions of 5-14 days duration. At one time point or another, EBV was detected in saliva from each of the astronauts. Of 1398 saliva specimens from 32 astronauts, polymerase chain reaction analysis showed that 314 (23%) were positive for EBV DNA. Examination by flight phase showed that 29% of the saliva specimens collected from 28 astronauts before flight were positive for EBV DNA, as were 16% of those collected from 25 astronauts during flight and 16% of those collected after flight from 23 astronauts. The mean number of EBV copies from samples taken during the flights was 417 per mL, significantly greater (p<.05) than the number of viral copies from the preflight (40) and postflight (44) phases. In contrast, the control subjects shed EBV DNA with a frequency of 3.7% and mean number of EBV copies of 40 per mL of saliva. Ten days before flight and on landing day, titers of antibody to EBV viral capsid antigen were significantly (p<.05) greater than baseline levels. On landing day, urinary levels of cortisol and catecholamines were greater than their preflight values. In a limited study (n=5), plasma levels of substance P and other neuropeptides were also greater on landing day. Increases in the number of viral copies and in the amount of EBV-specific antibody were consistent with EBV reactivation before, during, and after space flight.

Randomized Controlled Trial↗