ognizant Communication Corporation

International Journal for Human Support Research
(Formerly Life Support and Biosphere Science)


Habitation, Vol. 10, pp. 7-14
1542-9660/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Bioavailability of Iron From Spinach Using an In Vitro/Human Caco-2 Cell Bioassay Model*

Corinne J. Rutzke,1 Raymond P. Glahn,2 Michael A. Rutzke,2 Ross M. Welch,2 Robert W. Langhans,3 Louis D. Albright,1 Gerald F. Combs, Jr.,4 and Raymond M. Wheeler5

1Controlled Environment Agriculture Program, Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853
2United States Department of Agriculture-Agricultural Research Station, U.S. Federal Plant, Soil, and Nutrition Laboratory, Cornell University, Ithaca, New York 14853
3Controlled Environment Agriculture Program, Department of Horticulture, Cornell University, Ithaca, NY 14853
4Department of Nutritional Science, 122 Savage Hall, Cornell University, Ithaca, NY 14853
5Plant Biomass Production, Advanced Life Support, NASA, J.F. Kennedy Space Center, Kennedy Space Center, FL 32899

Spinach (Spinacia oleracea) cv Whitney was tested for iron bioavailabilty using an in vitro human intestinal cell culture ferritin bioassay technique previously developed. Spinach was cultured in a growth chamber for 33 days, harvested, and freeze-dried. Total iron in the samples was an average of 71 mg/g dry weight. Spinach was digested in vitro (pepsin and 0.1 M HCl followed by pancreatin and 0.1 M NaHCO3) with and without the addition of supplemental ascorbic acid. Caco-2 cell cultures were used to determine iron bioavailability from the spinach mixtures. Production of the iron-binding protein ferritin in the Caco-2 cells showed the supplemental ascorbic acid doubled bioavailability of iron from spinach. The data show fresh spinach is a poor source of iron, and emphasize the importance of evaluation of whole meals rather than single food items. The data support the usefulness of the in vitro/Caco-2 cell ferritin bioassay model for prescreening of space flight diets for bioavailable iron.

Key words: Iron; Bioavailability; Spinach; Caco-2 cells; Ferritin; Ascorbic acid

Address correspondence to Corinne Johnson Rutzke, Ph.D., Controlled Environment Agriculture Program, Department of Biological and Environmental Engineering, 120 Riley Robb Hall, Cornell University, Ithaca, NY 14853. Tel: (607) 255-2467; Fax: (607) 255-4080; E-mail: CFJ4@cornell.edu

*The use of a brand name, trademark, or proprietary product does not imply endorsement or constitute a guarantee or warranty of the product by USDA, NASA, or Cornell University and does not imply its approval to the exclusion of others that also may be suitable.

Habitation, Vol. 10, pp. 15-19
1542-9660/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Effects of Drying on Nitrification Activity in Zeoponic Medium Used for Long-Term Space Missions

R. L. McGilloway and R. W. Weaver

Soil and Crop Sciences Department, Texas A&M University, College Station, TX 77843-2474

One component of a proposed life support system is the use of zeoponic substrates, which slowly release NH4+ into "soil" solution, for the production of plants. Nitrifying bacteria that convert NH4+ to NO3- are among the important microbial components of these systems. Survival of nitrifying bacteria in dry zeoponic substrates is needed, because the substrate would likely be stored in an air-dry state between croppings. Substrate was enriched for nitrifying bacteria and allowed to air-dry in a laminar flow hood. Stored substrate was analyzed for nitrifier survivability by measuring nitrifier activity at the beginning, 3 days, 1, 2, and 3 weeks. After rewetting, activity was approximately 9 mg N g-1 h-1 regardless of storage time. Nitrification rates did not decrease during storage. It seems unlikely that drying between plantings would result in practical reductions in nitrification, and reinoculation with nitrifying bacteria would not be necessary.

Key words: Nitrifying bacteria; Nitrification; Zeoponics; Clay mineral

Address correspondence to Dr. Richard W. Weaver, Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843-2474. Tel: (979) 845-5323; Fax: (979) 845-5695; E-mail: rw-weaver@tamu.edu

Habitation, Vol. 10, pp. 21-36
1542-9660/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Online Model-Based Diagnosis to Support Autonomous Operation of an Advanced Life Support System

Gautam Biswas, Eric-Jan Manders, John Ramirez, Nagabhusan Mahadevan, and Sherif Abdelwahed

Department of EECS and Institute for Software Integrated Systems, Vanderbilt University, Nashville, TN 37235

This article describes methods for online model-based diagnosis of subsystems of the advanced life support system (ALS). The diagnosis methodology is tailored to detect, isolate, and identify faults in components of the system quickly so that fault-adaptive control techniques can be applied to maintain system operation without interruption. We describe the components of our hybrid modeling scheme and the diagnosis methodology, and then demonstrate the effectiveness of this methodology by building a detailed model of the reverse osmosis (RO) system of the water recovery system (WRS) of the ALS. This model is validated with real data collected from an experimental testbed at NASA JSC. A number of diagnosis experiments run on simulated faulty data are presented and the results are discussed.

Key words: Fault diagnosis; Detection; Estimation; Advanced life support systems; Water recovery system; Reverse osmosis system

Address correspondence to Gautam Biswas, Director of Graduate Studies, Computer Sicence, Institute for Software Integrated Systems (ISIS), Box 1824, Sta B, Room 254, Featheringill Hall, Vanberbilt University, Nashville, TN 37212. Tel: (615) 343-6204; Fax: (615) 343-6702; E-mail: Biswas@eecsmail.vuse.vanderbilt.edu

Habitation, Vol. 10, pp. 39-48
1542-9660/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Evidence of Pathogenic Microbes in the International Space Station Drinking Water: Reason for Concern?

Myron T. La Duc,1 Randall Sumner,2 Duane Pierson,3 Parth Venkat,1 and Kasthuri Venkateswaran1

1Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
2Bionetics Corp., Kennedy Space Center, FL
3Johnson Space Center, Houston, TX

Molecular analyses were carried out on four preflight and six postflight International Space Station (ISS)-associated potable water samples at various stages of purification, storage, and transport, to ascertain their associated microbial diversities and overall microbial burdens. Following DNA extraction, PCR amplification, and molecular cloning procedures, rDNA sequences closely related to pathogenic species of Acidovorax, Afipia, Brevundimonas, Propionibacterium, Serratia, and others were recovered in varying abundance. Retrieval of sequences arising from the iodine (biocide)-reducing Delftia acidovorans in postflight waters is also of concern. Total microbial burdens of ISS potable waters were derived from data generated by an ATP-based enumeration procedure, with results ranging from 0 to 4.9 x 104 cells/ml. Regardless of innate biases in sample collection and analysis, such circumstantial evidence for the presence of viable, intact pathogenic cells should not be taken lightly. Implementation of new cultivation approaches and/or viability-based assays are requisite to confirm such an occurrence.

Key words: International Space Station; Potable water; Pathogen; Molecular; 16S rDNA; Bioburden

Address correspondence to Myron T. La Duc, Biotechnology and Planetary Protection Group, M/S 89, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109. E-mail: mtladuc@jpl.nasa.gov

Habitation, Vol. 10, pp. 49-59
1542-9660/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Water Cycle and Its Management for Plant Habitats at Reduced Pressures

Vadim Y. Rygalov,1 Philip A. Fowler,2 Raymond M. Wheeler,3 and Ray A. Bucklin1

1University of Florida, Agricultural and Biological Engineering Department, Box 110570, Gainesville, FL 32611-0570
2Dynamac Corporation KSC NASA, Mail Code, DYN-3, Kennedy Space Center, FL 32899
3NASA, Kennedy Space Center NASA, Mail Code, YA-E4, Kennedy Space Center, FL 32899

Experimental and mathematical models were developed for describing and testing temperature and humidity parameters for plant production in bioregenerative life support systems. A factor was included for analyzing systems operating at low (10-101.3 kPa) pressure to reduce gas leakage and structural mass (e.g., inflatable greenhouses for space application). The expected close relationship between temperature and relative humidity was observed, along with the importance of heat exchanger coil temperature and air circulation rate. The presence of plants in closed habitats results in increased water flux through the system. Changes in pressure affect gas diffusion rates and surface boundary layers, and change convective transfer capabilities and water evaporation rates. A consistent observation from studies with plants at reduced pressures is increased evapotranspiration rates, even at constant vapor pressure deficits. This suggests that plant water status is a critical factor for managing low-pressure production systems. The approach suggested should help space mission planners design artificial environments in closed habitats.

Key words: Closed ecological system (CES); Water cycle; Water flux; Evaporation/condensation; Temperature; Relative humidity; Low pressure; Climate; Control

Address correspondence to Vadim Y. Rygalov, Assistant Professor, Space Studies Department, John Odegard School of Aerospace Studies, University of North Dakota, Grand Forks, ND. Tel: (701) 777-3197; Fax: (701) 777-3711; E-mail: vrygalov@aero.space.edu or vrygalov@aero.und

Habitation, Vol. 10, pp. 61-67
1542-9660/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Comparison of Different Cooling Regimes Within a Shortened Liquid Cooling/Warming Garment on Physiological and Psychological Comfort During Exercise

Gloria R. Leon,1 Victor S. Koscheyev,2 Aitor Coca,2 and Nathan List1

1Department of Psychology and 2Department of Kinesiology, University of Minnesota, Minneapolis, MN 55455

The aim of this study was to compare the effectiveness of different cooling regime intensities to maintain physiological and subjective comfort during physical exertion levels comparable to that engaged in during extravehicular activities (EVA) in space. We studied eight subjects (six males, two females) donned in our newly developed physiologically based shortened liquid cooling/warming garment (SLCWG). Rigorous (condition 1) and mild (condition 2) water temperature cooling regimes were compared at physical exertion levels comparable to that performed during EVA to ascertain the effectiveness of a lesser intensity of cooling in maintaining thermal comfort, thus reducing energy consumption in the portable life support system. Exercise intensity was varied across stages of the session. Finger temperature, rectal temperature, and subjective perception of overall body and hand comfort were assessed. Finger temperature was significantly higher in the rigorous cooling condition and showed a consistent increase across exercise stages, likely due to the restriction of heat extraction because of the intensive cold. In the mild cooling condition, finger temperature exhibited an overall decline with cooling, indicating greater heat extraction from the body. Rectal temperature was not significantly different between conditions, and showed a steady increase over exercise stages in both rigorous and mild cooling conditions. Ratings of overall comfort were 30% higher (more positive) and more stable in mild cooling (p < 0.001). The mild cooling regime was more effective than rigorous cooling in allowing the process of heat exchange to occur, thus maintaining thermal homeostasis and subjective comfort during physical exertion.

Key words: Physiological comfort; Subjective comfort; Optimal cooling regimes; Extravehicular activity (EVA)

Address correspondence to Gloria R. Leon, Ph.D., Department of Psychology, University of Minnesota, Elliott Hall, 75 E. River Rd., Minneapolis, MN 55455. Tel: (612) 625-9324; Fax: (612) 626-2079; E-mail: leonx003@umn.edu