Histological analysis of the aortic nerve in the rat raised in space (Rapid communication on Neurolab Project)

To study development of the aortic nerve baroreflex under conditions of microgravity, we examined the cross section of the left aortic nerve (LAN), which is the afferent of the baroreflex, in the neonate rats aged 25 days raised in microgravity on the space shuttle Columbia (flight:FLT group) for 16 days. In this paper, we report a part of the result obtained from the data of the myelinated fibers of LAN analyzed with an electron microscope. Two kind of ground control groups were compared to the FLT group; one was asynchronous ground control (AGC) group where the rats were housed in the same cage as that on the shuttle, and the other was vivarium(VIV) group where the rats were housed in a commercial cage. The LANs in each group were extirpated the from rats perfused with a fixative and embedded for histological analysis. We observed the transverse sections of LAN and took pictures of several areas (magnified to x 2K to x 200K). No irregular myelination was found in all fibers of FLT group when they were compared with two control groups. The thickness of myelin of the maximally myelinated fibers were 0.55 +/- 0.17 micrometer in FLT(n=5), 0.45 +/- 0.10 micrometer in AGC(n=5), and O.47 +/- 0.06 micrometer meter in VIV(n=5). There was no significant difference among three groups (unpared t-test). The results suggest that there is no effect of space environment on the myelin formation of each nerve fiber in the aortic nerve.

A monoclonal antibody that recognizes a common carbohydrate epitope shared by various glycoproteins in human secretions

A monoclonal antibody (mAb; a mouse IgM referred to as 1CF11) recognizing various human glycoproteins was obtained. While the immunoreaction of glycoproteins from human secretions including milk, saliva, and bronchus was demonstrated as a typical dose-responded S-shaped reaction curve on ELISA, no reaction was detected with milks and sera of animal origin as well as human serum. In the constituting polypeptides of the human milk secretory IgA molecule, only the secretory component was recognized by this mAb. Among various chemical treatments of the purified human milk lactoferrin (Lf), only either periodate or mild alkaline treatment abolished the immunoreactivity of the glycoprotein. A recombinant human Lf was not immunoreactive. Finally, the immunoreactive fragments were isolated from human milk Lf, which remained reactive with PAS reagent while lacking the previously reported N-glycans. These results strongly suggest that the mAb 1CF11 recognizes a new glycan O-glycosidically linked to glycoproteins in human secretions.

Dual regulatory effects of interferon-alpha, -beta, and -gamma on interleukin-8 gene expression by human gingival fibroblasts in culture upon stimulation with lipopolysaccharide from Prevotella intermedia, interleukin-1alpha, or tumor necrosis factor-alpha

In a previous study, we demonstrated that the amount of interleukin (IL)-8 mRNA expressed by human gingival fibroblasts stimulated with lipopolysaccharide (LPS) from Prevotella intermedia ATCC 25611 is increased by pre-treatment with beta or gamma interferon (IFN-beta or -gamma). In the present study, we identified the regulatory effects of these IFNs on IL-8 mRNA expression and IL-8 production by human gingival fibroblasts. Priming with IFN-alpha (alpha), -beta, or -gamma upregulated the IL-8 mRNA expression in response to P. intermedia LPS, whereas co-stimulation with these IFNs reduced the amount of mRNA expressed by the cells. The regulation of IL-8 mRNA expression induced by recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) or rHuIL-1alpha was similar to that induced by LPS. The IL-8 mRNA expression in response to P. intermedia LPS was enhanced by IFN-gamma independently of de novo protein synthesis, and was regulated, at least in part, at the transcriptional level. The IL-8 mRNA accumulation in response to P. intermedia LPS was inhibited by tosylphenyl-alanyl chloromethyl-ketone, an inhibitor of NF-kappaB activation, although the NF-kappaB activation itself was not altered by IFN-gamma. These findings suggest that IFNs might be capable of both enhancing and inhibiting inflammatory responses in periodontal tissues through the dual regulation of IL-8 production by gingival fibroblasts in response to bacterial components and cytokines.

Spaceflight modulates insulin-like growth factor binding proteins and glucocorticoid receptor in osteoblasts

Rat osteoblasts were cultured for 4 or 5 days during a Space Shuttle mission. After 20-h treatment with 1alpha,25-dihydroxyvitamin D3, conditioned media were harvested and cellular DNA and/or RNA were fixed on board. The insulin-like growth factor binding protein (IGF BP)-3 levels in the media were three- and tenfold higher than in ground controls on the fourth and fifth flight days, as quantitated by Western ligand blotting and radioimmunoassay, respectively. The increased IGF BP-3 protein levels correlated with two- to threefold elevation of IGF BP-3 mRNA levels, obtained by reverse transcription-polymerase chain reaction. The IGF BP-5 mRNA levels in flight cultures were 33-69% lower than in ground controls. The IGF BP-4 mRNA levels in flight cultures were 75% lower than in ground controls on the fifth day but were not different on the fourth day. The glucocorticoid receptor mRNA levels in flight cultures were increased by three- to eightfold on the fourth and fifth days compared with levels in ground controls. These data suggest potential mechanisms underlying spaceflight-induced osteopenia.

Lethality of high linear energy transfer cosmic radiation to Escherichia coli DNA repair-deficient mutants during the 'SL-J/FMPT' space experiment

We investigated the lethal and mutagenic effects of high linear energy transfer cosmic radiation on 11 strains of Escherichia coli, including DNA repair-deficient mutants, using the Radiation Monitoring Container and Dosimeter in the space shuttle 'Endeavour' as part of the 'SL-J/FMPT' space experiment, the 'Fuwatto '92' project. After the return to earth of the shuttle, we evaluated survival and mutations of samples in space and matched controls. The surviving fractions were determined by means of colony count on broth agar plates, and the mutation frequencies were estimated by appearance of arg' revertants on minimal agar plates. The average of the total equivalent dose rate during this space flight was 0.202 mSv/day as measured by the plastic radiation detectors and the thermoluminescent dosimeters in the Radiation Monitoring Container and Dosimeter. The combined action of DNA polymerase and 3'-->5' exonuclease activities was found to make the greatest contribution to the repair of cosmic radiation-induced DNA damage, 5'-->3' exonuclease and recombination repair enzyme activities made a moderate contribution, whereas UV endonuclease activity was not involved in this DNA repair process.

Anti-transfer RNA antibodies in two patients with pulmonary fibrosis, Raynaud's phenomenon and polyarthritis

Patient W.S. (a 61-year-old woman) and patient T.M. (a 41-year-old man) developed recurrent fevers, polyarthritis, Raynaud's phenomenon and interstitial pulmonary fibrosis without apparent polymyositis. From HeLa cell extracts, sera from both patients immunoprecipitated all species of intact and deproteinised tRNAs. To identify the antibody binding site more precisely, tRNAs transcribed in vitro from cloned Escherichia coli tRNA genes and various mutants were prepared and used as antigens for immunoprecipitation. When the TpsiC loop, or the D loop were deleted, such mutants were not bound by both sera, suggesting that the D and TpsiC loops were required for antibody binding. Abrogation of tRNA binding occurred when 18G of tRNATrp was replaced with 18A to break the tertiary L-shape structure of tRNA. These results strongly suggest that sera from W.S. and T.M. recognise the tertiary conformation of L-shaped tRNA which is constructed with both D and TpsiC loops. These autoantibodies may also serve as a marker for a new subset of patients with connective tissue diseases that is distinct from anti-aminoacyl-tRNA synthetase syndrome.

Inhibition in a microgravity environment of the recovery of Escherichia coli cells damaged by heavy ion beams during the NASDA ISS phase I program of NASA Shuttle/Mir mission no. 6

We participated in a space experiment, part of the National Space Development Agency of Japan (NASDA) Phase I Space Radiation Environment Measurement Program, conducted during the National Aeronautics and Space Administration (NASA) Shuttle/Mir Mission No. 6 (S/MM-6) project. The aim of our study was to investigate the effects of microgravity on the DNA repair processes of living organisms in the <Realtime Radiation Monitoring Device III (RRMD III)> in orbit. Heavy ion beam radiation- or ç-irradiation-damaged biological samples of Escherichia coli and the radioresistant bacterium Deinococcus radiodurans were prepared and placed in a biospecimen box, which was loaded into the RRMD III sensor unit of the Space Shuttle. Two identical sets of samples were left in the Spacehab's Payload Processing Facility (SPPF) in Florida, USA, as a control. (flight No. STS-84) was launched from NASA John F. Kennedy Space Center (KSC) in Florida, USA, on May 15, 1997. The mission duration was 9.22 days. An astronaut activated the biological samples in the biospecimen box in the Spacehab during orbit in order to start repair of the DNA damaged by heavy ion beams or ç-irradiation and the samples were incubated for 19 h 35 min at about 22ûC, the cabin temperature. The control specimens in the SPPF were subjected to the same treatment under terrestrial gravity. After returned to earth, we investigated cell recovery by comparing the repair of the radiation-damaged DNA of E. coli and D. radiodurans in the microgravity environment in space with that on Earth. The results indicated that the DNA repair process of E. coli, but not of D. radiodurans, cells was inhibited in a microgravity environment.

Effects of SS320A, a new cysteine derivative, on the change in the number of goblet cells induced by isoproterenol in rat tracheal epithelium

We examined the effects of SS320A ((-)-(R)-2-amino-3-(3-hydroxypropylthio)propionic acid), a new cysteine derivative, on the change in the number of goblet cells induced by isoproterenol in rat tracheal epithelium. Four types of goblet cells were characterized in tracheal epithelium according to their size and staining affinity with Alcian blue (AB) / periodic acid Schiff (PAS). When each rat was given a single daily injection of isoproterenol (0.05 mg/kg, i.p.) for 14 days, a significant increase was observed in AB/PAS-positive cells that were recognizable as goblet cells in tracheal epithelium. When SS320A (10-100 mg/kg, p.o.) or propranolol (1 mg/kg, s.c.) was administered before each injection of isoproterenol, the increase in the number of goblet cells induced by isoproterenol was significantly inhibited. There was no difference between male and female rats with regard to this inhibitory action. On the other hand, ambroxol, bromhexine, L-cysteine ethyl ester and S-carboxymethylcysteine (100 mg/kg, p.o., respectively), which are used as expectorants, had no inhibitory effects on the isoproterenol-induced change in the number of goblet cells. Four metabolites (M1-M4) of SS320A in rats also failed to inhibit the change induced by isoproterenol. These data suggest that SS320A itself may have a beneficial effect against mucus hypersecretion in chronic respiratory diseases.

Effects of SS320A, a new cysteine derivative, on the change in the number of goblet cells induced by bacterial endotoxin in rat tracheal epithelium

We examined the effects of SS320A, a new cysteine derivative, on the change in the number of goblet cells induced by bacterial endotoxin in rat tracheal epithelium. Four types of goblet cell were characterized in tracheal epithelium according to their size and staining affinity with Alcian blue (AB)/periodic acid Schiff (PAS). Each rat was intratracheally given a single instillation of lipopolysaccharide (LPS) (2 mg/ml). The results showed that treatment with LPS increased the number of AB/PAS-positive cells that were recognizable as goblet cells in tracheal epithelium. On the other hand, LPS evoked acute lung inflammation related to neutrophil accumulation in the lung before the increase in goblet cells. SS320A (10-100 mg/kg, p.o.) and dexamethasone (10 mg/kg, p.o.) each significantly inhibited the increase in the number of goblet cells induced by LPS. On the other hand, ambroxol, bromhexine, l-cysteine ethyl ester and S-carboxymethylcysteine, which are used as expectorants, had no inhibitory effects on the LPS-induced change in the number of goblet cells. SS320A slightly inhibited the lung injury based on a histological examination. These data suggest that SS320A may have a beneficial effect against mucus hypersecretion in respiratory disease.

Characterization of gene expression in mouse blastocyst using single-pass sequencing of 3995 clones

To study the gene expression profile in the mouse blastocyst and to identify embryonic stage-specific genes, we randomly selected cDNAs derived from mouse blastocysts and sequenced a total of 3995 clones from one or both ends. Excluding the uninformative clones, 3395 clones were grouped as 937 different kinds of genes. Among these, 465 and 406 species showed similarity to known genes and expressed sequence tags (ESTs), respectively, whereas 66 species showed no significant similarity to any genes in known databases. Analysis of these cDNAs revealed that this library contained a variety of functional genes as well as genes that have not been detected in the human EST database; it should provide us with a useful resource for molecular analysis of developmental mechanisms. Although the human EST project is considered to represent roughly half of all genes, our findings indicate that many early stage developmental genes remain to be identified.

[Emphasis of biological research for space radiation]

The paper summarized issues, current status and the recent topics in biological research of space radiation. Researches to estimate a risk associated with space radiation exposure during a long-term manned space flight, such as in the International Space Station, is emphasized because of the large uncertainty of biological effects and a complexity of the radiation environment in space. The Issues addressed are; 1) biological effects and end points in low dose radiation, 2) biological effects under low dose rate and long-term radiation exposure, 3) modification of biological responses to radiation under space environments, 4) various aspects of biological end points vs. cellular and molecular mechanisms, 5) estimation of human risk associated with radiation exposure in space flight, 6) regulations for radiation exposure limits for space workers. The paper also summarized and introduced recent progress in space related radiation researches with various biological systems.

Effects of space flight on GLUT-4 content in rat plantaris muscle

The effects of 14 days of space flight on the glucose transporter protein (GLUT-4) were studied in the plantaris muscle of growing 9-week-old, male Sprague Dawley rats. The rats were randomly separated into five groups: pre-flight vivarium ground controls (PF-VC) sacrificed approximately 2 h after launch; flight groups sacrificed either approximately 5 h (F-R0) or 9 days (F-R9) after the return from space; and synchronous ground controls (SC-R0 and SC-R9) sacrificed at the same time as the respective flight groups. The flight groups F-R0 and F-R9 were exposed to micro-gravity for 14 days in the Spacelab module located in the cargo bay of the shuttle transport system--58 of the manned Space Shuttle for the NASA mission named "Spacelab Life Sciences 2". Body weight and plantaris weight of SC-R0 and F-R0 were significantly higher than those of PF-VC. Neither body weight nor plantaris muscle weight in either group had changed 9 days after the return from space. As a result, body weight and plantaris muscle weight did not differ between the flight and synchronous control groups at any of the time points investigated. The GLUT-4-content (cpm/microgram membrane protein) in the plantaris muscle did not show any significant change in response to 14 days of space flight or 9 days after return. Similarly, citrate synthase activity did not change during the course of the space flight or the recovery period. These results suggest that 14 days of space flight does not affect muscle mass or GLUT-4 content of the fast-twitch plantaris muscle in the rat.

Thermostabilization and thermoactivation of thermolabile enzymes by trehalose and its application for the synthesis of full length cDNA

The advent of thermostable enzymes has led to great advances in molecular biology, such as the development of PCR and ligase chain reaction. However, isolation of naturally thermostable enzymes has been restricted to those existing in thermophylic bacteria. Here, we show that the disaccharide trehalose enables enzymes to maintain their normal activity (thermostabilization) or even to increase activity at high temperatures (thermoactivation) at which they are normally inactive. We also demonstrate how enzyme thermoactivation can improve the reverse transcriptase, reaction. In fact, thermoactivated reverse transcriptase, which displays full activity even at 60 degrees C, was powerful enough to synthesize full length cDNA without the early termination usually induced by stable secondary structures of mRNA.

Accumulation of stress protein 72 (HSP72) in muscle and spleen of goldfish taken into space

Using Western blot analysis, here, we report the levels of HSP72 in several organs from goldfish which were taken into space on the NASA space shuttle. A remarkable accumulation of HSP72 was detected in muscle and spleen of those fish taken into space as compared with controls. These results suggested that the HSP72 induction is a kind of stress response at the molecular level introduced by the space environment consisting of microgravity and/or cosmic radiation as stressors.

A novel control system for polymerase chain reaction using a RIKEN GS384 thermalcycler

We have developed a novel high-throughput thermalcycler, the RIKEN GS384, which has a maximum of 1536 wells and whose temperature can be controlled accurately and simultaneously for a very small volume of a reaction mixture. In practice, the reaction is carried out using four 384-well (3.5 mm in diameter) plate formats which can be automatically moved using a robotic arm. To achieve accurate temperature control with high thermo-conductivity, we adopted Teflon-coated aluminum well plates closely sandwiched between silicon sheet-covered lids on top and a graphite sheet below. The lids were kept at a higher temperature (2 to 5 degrees C) than the reaction wells. The temperature of the 1536 sample wells was controlled accurately without temperature variability among the wells or evaporation, even for samples of very small volume (minimum 2 microliters). We also developed a new type of plate format which is similar to the 384-well place in terms of plate size, shape, and material, but which differs in the number (1536) and size (1.6 mm in diameter) of the wells. Since the amplification reactions could be done precisely as well, a total of 6144 reactions can potentially be carried out simultaneously using the GS384 thermalcycler. This is very promising for DNA microfabrication technology. This thermalcycler offers the advantage of high-throughput DNA analysis which should be useful for DNA diagnoses or for the human genome project.

Radiation dosimetry measurements with real time radiation monitoring device (RRMD)-II in Space Shuttle STS-79

The real-time measurement of radiation environment was made with an improved real-time radiation monitoring device (RRMD)-II onboard Space Shuttle STS-79 (S/MM#4: 4th Shuttle MIR Mission, at an inclination angle of 51.6 degrees and an altitude of 250-400km) for 199 h during 17-25 September, 1996. The observation of the detector covered the linear energy transfer (LET) range of 3.5-6000 keV/micrometer. The Shuttle orbital profile in this mission was equivalent to that of the currently planned Space Station, and provided an opportunity to investigate variations in count rate and dose equivalent rate depending on altitude, longitude, and latitude in detail. Particle count rate and dose equivalent rate were mapped geographically during the mission. Based on the map of count rate, an analysis was made by dividing whole region into three regions: South Atlantic Anomaly (SAA) region, high latitude region and other regions. The averaged absorbed dose rate during the mission was 39.3 microGy/day for a LET range of 3.5-6000 keV/micrometer. The corresponding average dose equivalent rates during the mission are estimated to be 293 microSv/day with quality factors from International Commission on Radiological Protection (ICRP)-Pub. 60 and 270 microSv/day with quality factors from ICRP-Pub. 26. The effective quality factors for ICRP-Pub. 60 and 26 are 7.45 and 6.88, respectively. From the present data for particles of LET > 3.5keV/micrometer, we conclude that the average dose equivalent rate is dominated by the contribution of galactic cosmic ray (GCR) particles. The dose-detector depth dependence was also investigated.

Measurements of LET distribution and dose equivalent onboard the Space Shuttle IML-2 (STS-65) and S/MM#4 (STS-79)

Space radiation dosimetry measurements have been made onboard the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2: 28.5 degrees x 300 km: 14.68 days) and the STS-79 in the 4th Shuttle MIR mission (S/MM#4: 51.6 degrees x 300-400km: 10.2 days). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD-I for IML-2 and RRMD-II with improved triggering system for S/MM#4)" utilizing silicon semi-conductor detectors and the other detectors are conventional passive detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. The main contribution to dose equivalent for particles with LET > 5.0 keV/micrometer (IML-2) and LET > 3.5 keV/micrometer (S/MM#4) is seen to be due to galactic cosmic rays (GCRs) and the contribution of the South Atlantic Anomaly (SAA) is less than 5% (IML-2: 28.5 degrees x 300 km) and 15% (S/MM#4: 51.6 degrees x 400 km) in the above RRMD LET detection conditions. For the whole LET range (> 0.2 kev/micrometer) obtained by TLDs and CR-39 in these two typical orbits (a small inclination x low altitude and a large inclination x high altitude), absorbed dose rates range from 94 to 114 microGy/day, dose equivalent rates from 186 to 207 microSv/day and average quality factors from 1.82 to 2.00 depending on the locations and directions of detectors inside the Spacelab at the highly protected IML-2 orbit (28.5 degrees x 300 km), and also, absorbed dose rates range from 290 to 367 microGy/day, dose equivalent rates from 582 to 651 microSv/day and average quality factors from 1.78 to 2.01 depending on the dosimeter packages around the RRMD-II "Detector Unit" at the S/MM#4 orbit (5l.6 degrees x 400km). In general, it is seen that absorbed doses depend on the orbit altitude (SAA trapped particles contribution dominant) and dose equivalents on the orbit inclination (GCR contribution dominant). The LET distributions obtained by two different types of active and passive detectors, RRMDs and CR-39, are in good agreement for LET of 15 - 200 kev/micrometer and difference of these distributions in the regions of LET < 15 kev/micrometer and LET > 200 kev/micrometer can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks and chemical etching conditions.