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James, J.

Publications and source records attributed to James, J..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

Modeling of Blood Lead Levels in Astronauts Exposed to Lead from Microgravity-Accelerated Bone Loss

Human exposure to lead has been associated with toxicity to multiple organ systems. Studies of various population groups with relatively low blood lead concentrations (<10 μg/dL) have indicated associations of blood lead level with lower cognitive test scores in children, later onset of puberty in girls, and increased blood pressure and cardiovascular mortality rates in adults. Cognitive effects are considered by regulatory agencies to be the most sensitive endpoint at low doses. Although ~95% of the body burden of lead is stored in the bones, the adverse effects of lead correlate with the concentration of lead in the blood better than with that in the bones. NASA has found that prolonged exposure to microgravity during spaceflight results in a significant loss of bone minerals, the extent of which varies from individual to individual and from bone to bone, but generally averages about 0.5% per month. During such bone loss, lead that had been stored in bones would be released along with calcium. The effects on the concentration of lead in the blood (PbB) of various concentrations of lead in drinking water (PbW) and of lead released from bones due to accelerated osteoporosis in microgravity, as well as changes in exposure to environmental lead before, during, and after spaceflight were evaluated using a physiologically based pharmacokinetic (PBPK) model that incorporated exposure to environmental lead both on earth and in flight and included temporarily increased rates of osteoporosis during spaceflight.

Garcia, H.↗
NASA NTRS2014

Chronic Lunar Dust Exposure on Rat Cornea: Evaluation by Gene Expression Profiling

Lunar dust is capable of entering habitats and vehicle compartments by sticking to spacesuits or other objects that are transferred into the spacecraft from the lunar surface and has been reported to cause irritation upon exposure. During the Apollo missions, crewmembers reported irritation specifically to the skin and eyes after contamination of the lunar and service modules. It has since been hypothesized that ocular irritation and abrasion might occur as a result of such exposure, impairing crew vision. Recent work has shown that both ultrafine and unground lunar dust exhibited minimal irritancy of the ocular surface (i.e., cornea); however, the assessment of the severity of ocular damage resulting from contact of lunar dust particles to the cornea has focused only on macroscopic signs of mechanical irritancy and cytotoxicity. Given the chemical reactive properties of lunar dust, exposure of the cornea may contribute to detrimental effects at the molecular level including but not limited to oxidative damage. Additionally, low level chronic exposures may confound any results obtained in previous acute studies. We report here preliminary results from a tissue sharing effort using 10‐week‐old Fischer 344 male rats chronically exposed to filtered air or jet milled lunar dust collected during Apollo 14 using a Jaeger‐NYU nose‐only chamber for a total of 120 hours (6 hours daily, 5 days a week) over a 4‐week period. RNA was isolated from corneas collected from rats at 1 day and 7 days after being exposed to concentrations of 0, 20, and 60 mg/m3 of lunar dust. Microarray analysis was performed using the Affymetrix GeneChip Rat Genome 230 2.0 Array with Affymetrix Expression Console and Transcriptome Analysis Console used for normalization and secondary analysis. An Ingenuity iReport"TM" was then generated for canonical pathway identification. The number of differentially expressed genes identified increases with dose compared to controls suggesting a more severe response to the lunar dust insult at higher levels. Pathways of interests that have been identified in all exposed samples include oxidative stress response, mitochondrial dysfunction, fibrosis, epithelial healing, TGF-Beta signaling, and extracellular matrix remodeling. Several biological processes related to cell migration, cellular proliferation, and eye development were also identified to be altered by exposure to lunar dust. Our preliminary results suggest that even a chronic insult of lunar dust as low as 20 mg/m(exp 3) elicits a molecular response in cornea tissue. Lunar dust on the surface of the moon would have the added properties of ionization and activation potentially leading to further damage to the cornea and greater sensitivity to any other environmental insult such as exposure to radiation. Additional studies are required to fully assess the risk of vision impairment and the mechanistic responses initiated in cornea exposed to lunar dust as well as the potential for long‐term effects to astronaut health

Theriot, C. A.↗
NASA NTRS1999

JSC Toxicology Web Site

Data on chemical and biological materials to be flown in the pressurized volumes of habitable spacecraft, including the International Space Station (ISS), are needed by JSC toxicologists to assess the toxicity and assign hazard levels. This document defines submission schedules and establishes requirements for the types and format of these data. JSC 27472 Rev A is a major revision of JSC 25607, "Requirements for Submission of Test Sample-Materials Data for Shuttle Payload Safety Evaluations", dated October 1994, which was subsequently re-issued (September 1996) with a new document number, JSC 27472, but with the same title and date and no revisions. The revisions in the present document have been necessitated by the recent introduction of a two-step process (described in this document) for verification of data for flight materials and by the anticipated needs of the ISS. The requirements -for data submission apply to items which contain liquids, gases, gels, greases, powders/ particulates, radioisotopes, or biological materials and are located in the habitable pressurized volume of ISS or U.S. operated spacecraft. These include, but are not limited to, science payloads, government furnished equipment (GFE), risk mitigation experiments (RmEs), development test objectives (DTOs), detailed supplementary objectives (DSOs), life science experiments, and medical studies.

Garcia, Hector D.↗
NASA NTRS1997

Results From Phase-1 and Phase-2 GOLD Experiments

The Ground/Orbiter Lasercomm Demonstration conducted between the Japanese Engineering Test Satellite (ETS-VI) and the ground station at JPL's Table Mountain Facility, Wrightwood, California, was the rst ground-to-space two-way optical communications experiment. Experiment objectives included validating the performance predictions of the optical link. Atmospheric attenuation and seeing measurements were made during the experiment, and data were analyzed. Downlink telemetry data recovered over the course of the experiment provided information on in-orbit performance of the ETS-VI's laser communications equipment. Biterror rates as low as 10 4 were measured on the uplink and 10 5 on the downlink. Measured signal powers agreed well with theoretical predictions.

Wilson, K.↗
NASA NTRS1997

Data Analysis Results From the GOLD Experiments

Analyses of uplink and downlink data from recent free-space optical communications experiments carried out between Table Mountain Facility (near Pasadena, CA) and the Japanese ETS-VI satellite are presented.

Free-space↗
NASA NTRS1996

Long Wavelength 256 X 256 Quantum Well Infrared Photodetector Portable Camera

In this paper, we discuss the development of very sensitive long wavelength infrared (LWIR) GaAs/AlGal-xAs Quantum well infrared photodetectors (QWIPS), fabrication of random reflectors for efficient light coupling, and the demonstration of a LWIR 256 X 256 focal plane array imaging camera. Excellent imagery, with a noise equivalent differential temperature (NE-delta-T) of 25 mK has been achieved.

long wavelength inrared photodetectors random refl↗