ALBERT

Description: A fully integrated, miniaturized analysis system for ions based on a centrifugal microfluidics platform and ion-selective optode membranes is described. The microfluidic architecture is composed of channels, five solution reservoirs, a measuring chamber, and a waste reservoir manufactured onto a disk-shaped substrate of poly(methyl methacrylate). Ion-selective optode membranes, composed of plasticized poly(vinyl chloride) impregnated with an ionophore, a proton chromoionophore, and a lipophilic anionic additive, were cast, with a spin-on device, onto a support layer and then immobilized on the disk. Fluid propulsion is achieved by the centrifugal force that results from spinning the disk, while a system of valves is built onto the disk to control flow. These valves operate based on fluid properties and fluid/substrate interactions and are controlled by the angular frequency of rotation. With this system, we have been able to deliver calibrant solutions, washing buffers, or "test" solutions to the measuring chamber where the optode membrane is located. An analysis system based on a potassium-selective optode has been characterized. Results indicate that optodes immobilized on the platform demonstrate theoretical responses in an absorbance mode of measurement. Samples of unknown concentration can be quantified to within 3% error by fitting the response function for a given optode membrane using an acid (for measuring the signal for a fully protonated chromoionophore), a base (for fully deprotonated chromoionophore), and two standard solutions. Further, the ability to measure ion concentrations by employing one standard solution in conjunction with acid and base and with two standards alone were studied to delineate whether the current architecture could be simplified. Finally, the efficacy of incorporating washing steps into the calibration protocol was investigated.

Description: Herpesviruses are leading causes of infectious blindness and death in immunocompromised individuals. Impaired cellular immunity, which is known to result in increased frequency and severity of herpesvirus infections, has been demonstrated both during and after spaceflight. Therefore, we examined whether Epstein-Barr virus (EBV), a well-characterized latent herpesvirus, undergoes reactivation in astronauts. Sera from Shuttle astronauts, taken before and after spaceflight, were examined for evidence of EBV reactivation. The geometric mean antibody titer to EBV viral capsid antigen (VCA) was significantly increased prior to flight compared to baseline (p = 0. 0001). After spaceflight, evidence of acute lytic replication was found in which 8- to 64-fold increases in EBV early antigen (EA) antibodies occurred without significant increases in antibodies to measles virus. Additionally, stress-induced shifts in circulating leukocytes and elevated levels of urinary cortisol and epinephrine were found. Overall, significant increases in EA or high VCA/EA antibody titers were found in 8 of 23 (35%) male astronauts and 3 of 5 (60%) female astronauts. These results indicate that stress reactivates EBV prior to flight and suggest that acute lytic replication of EBV occurs during spaceflight. Copyright 2000 S. Karger AG, Basel.

Description: Human collaboration in distributed knowledge sharing groups depends on the functionality of information and communication technologies (ICT) to support performance. Since many of these dynamic environments are constrained by time limits, knowledge must be shared efficiently by adapting the level of information detail to the specific situation. This paper focuses on the process of knowledge and context sharing with and without mediation by ICT, as well as issues to be resolved when determining appropriate ICT channels. Both technology-rich and non-technology examples are discussed.

Description: Swiss Webster male and female mice (150 of each) were fed NASA Rodent Foodbar for more than 110 days to test the diet's nutritional adequacy for use in future long-term studies aboard the International Space Station. Mice were grouped three to a cage (one cage = one sample) and cages were assigned to either Foodbar or Purina Chow #5001 (control) diet groups. Body weights, food intake, and water intake were obtained throughout the study. There were no significant differences in body weights between male Foodbar fed and Chow fed males (p=0.58), and at 15 weeks into the female mouse study there appear to be no significant body weight differences. Both male and female Foodbar fed groups consumed more food and less water than their Chow controls, both factors thought to be attributable to the high moisture content of the Foodbars (26% versus 10% for Chow). All differences in gross food and water consumption had p-values of less than 0.01. When food and water intake were adjusted for the moisture content in the food, both male and female Foodbar fed animals consumed less food, but still had a lower water intake rate than their controls. (p is less than 0.01). Preliminary analysis on blood samples from male and female halfway point dissections suggests differences in glucose and fat metabolism. In both male and female Foodbar fed animals, blood glucose values were significantly lower (p is less than 0.01) but there were no significant differences in cholesterol levels (p=0.51). In Foodbar fed females, triglycerides were significantly higher (p is less than 0.01). These data suggest that Foodbars allow for normal growth in Swiss Webster mice, but affect some blood chemistry parameters.

Description: A specialized rodent food bar diet has been developed and utilized successfully for short-duration shuttle missions. Recent tests conducted in preparation for experiments aboard the International Space Station (ISS) indicated that long-term food bar feeding for three months induced hyperlipidemia in rats. This study examined oxidative stress status in livers of these same animals. Spectrophotometric analysis of 79 Fischer rat livers (40 female and 39 male) for lipid peroxidation (LPO) and superoxide dismutase (SOD) was conducted using Bioxytech LPO-587(TM) assay kit and SOD-525(Tm) assay kit, respectively. The treatment groups consisted of 20 male CHOW and 19 male FOOD BAR rats and 20 female CHOW and 20 female FOOD BAR rats. Statistical analysis to compare differences between groups was performed by standard analysis of variance procedures. The male FOOD BAR group LPO mean (3.6 +/- 0.2 mmol/g) was significantly (p less than or equal to 0.05) greater than that of the male CHOW group (2.1 +/-0.1 mmol/g). Moreover the female FOOD BAR group LPO mean (2.9 +/-0.1 mmol/g) was also significantly greater than the female CHOW group mean (2.2 +/-0.1 mmol/g). The mean values for SOD in both male and female groups showed no significant differences between CHOW and FOOD BAR groups. These results show that LPO levels were significantly higher in both the male and female FOOD BAR groups compared to CHOW groups and that there was no concomitant increase in SOD levels across the group. In addition, males showed a greater difference than females in terms of LPO levels. These findings suggest a need for further investigation into the use of the current food bar formulation for long-term experiments such as those planned for the ISS.

Description: The objective of this study is to test the nutritional adequacy of the NASA Rodent Foodbar for long term use for rats. The Foodbar was tested on two rat strains, Sprague Dawley and Fischer 344. Rats were fed either Foodbar or the control diet, Purina Chow #5012. Body composition analysis was performed on a selected number of samples (n=6 for each gender and treatment group) as part of extensive testing of the Foodbar. Water, fat, ash, and protein (and their percentages) for both treatment groups were compared. Sprague Dawley Foodbar fed rats had a lower % protein than Chow fed rats (25.8% vs. 30.0%). In addition, Sprague Dawley females fed Foodbar had higher total fat (42.1g vs. 24.6g) and % fat (16.4% vs. 10.5%), but lower % water (51.3% vs. 54.8%) than Sprague Dawley females fed Chow. Fischer 344 Foodbar fed rats had a lower % water (47.4% vs. 49,3%) and total water (93.2g vs. 99.6g). In addition, Fischer 344 Foodbar males had higher % fat (17.0% vs. 13.8%) and total fat (43.0g vs. 34.7g). The data suggests that body composition of Foodbar fed rats tends to have lower water content but a higher fat content compared to controls, but not all results are the same for different strains and even different genders within the same strains. The data obtained here, in addition to other data, helps provide a better understanding of the nutritional adequacy of the Foodbar and whether the formula may need to be modified.

Description: Tests are being conducted on NASA's rodent Food Bar in preparation for long-term use as the rat and mouse diet aboard the International Space Station. Nutritional analyses are performed after the bars are manufactured and then repeated periodically to determine nutritional stability. The primary factors analyzed are protein, ash, fat, fiber, moisture, amino acids, fatty acids, and minerals. Nutrient levels are compared to values published in the National Research Council's dietary requirements for rodents, and also to those contained in several commonly used commercial rodent lab diets. The Food Bar is manufactured from a powdered diet to which moisture is added as it is processed through an extruder. The bars are dipped into potassium sorbate, vacuum-sealed, and irradiated. In order to determine nutrient changes during extrusion and irradiation, the powdered diet, the non-irradiated bars, and the irradiated bars are all analyzed. We have observed lower values for some nutrients (iodine, vitamin K, and iron) in the Food Bars compared with NRC requirements. Many nutrients in the Food Bars are contained at a higher level than levels in the NRC requirements. An additional factor we are investigating is the 26% moisture level in the Food Bars, which drops to about 15% within a week, compared to a stable 10% moisture in many standard lab chow diets. In addition to the nutritional analyses, the food bar is being fed to several strains of rats and mice, and feeding study and necropsy results are being observed (Barrett et al, unpublished data). Information from the nutritional analyses and from the rodent studies will enable us to recommend the formulation that will most adequately meet the rodent Food Bar requirements for long-term use aboard the Space Station.

Description: A standard rodent diet for space flight must meet the unique conditions imposed by the space environment and must be nutritionally adequate since diet can influence the outcome of experiments. This paper evaluates the use of National Aeronautics and Space Administration (NASA) developed Foodbars as a standard space flight diet for rats. The Foodbar's semi-purified formulation permits criteria such as nutrient consistency, high nutrient bioavailability and flexibility of formulation to be met. Extrusion of the semi-purified diet produces Foodbars with the proper texture and a non-crumbing solid form for use in space. Treatment of Foodbar with 0.1% potassium sorbate prevents mold growth. Irradiation (15-25 kGy) prevents bacterial growth and in combination with sorbate-treatment provides added protection against mold for shelf-stability. However, during the development process, nutrient analyses indicated that extrusion and irradiation produced nutrient losses. Nutrients were adjusted accordingly to compensate for processing losses. Nutrient analysis of Foodbars continues to be performed routinely to monitor nutrient levels. It is important that the standard rodent diet provide nutrients that will prevent deficiency but also avoid excess that may mask physiological changes produced by space flight. All vitamins levels in the Foodbars, except for vitamin K conformed to or exceeded the current NRC (1995) recommendations. All indispensable amino acids in Foodbar conformed to or exceeded the NRC nutrient recommendation for mice growth and rat maintenance. However, some indispensable amino acids were slightly below recommendations for rat reproduction/growth. Short-term (18-20 d) animal feeding studies indicated that Foodbars were palatable, supported growth and maintained health in rats. Results indicated that NASA rodent Foodbars meet both the physical and nutritional criteria required to support rodents in the space environment and thus, may be used successfully as a standard diet for short-term space flight studies. However, nutritional adequacy of NASA Rodent Foodbars as a standard diet on longer duration (〉20 d) space flight missions remains to be determined.