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Acute erythroleukemia (AEL) is a rare subtype of acute myeloid leukemia with a poor prognosis. In this study, we established a novel murine AEL model with Trp53 depletion and ERG overexpression. ERG overexpression in Trp53-deficient mouse bone marrow cells, but not in wild-type bone marrow cells, leads to AEL development within two months after transplantation with 100% penetrance. The established mouse AEL cells expressing Cas9 can be cultured in vitro, induce AEL in vivo even in unirradiated recipient mice, and enable efficient gene ablation using the CRISPR/Cas9 system. We also confirmed the cooperation between ERG overexpression and TP53 inactivation in promoting the growth of immature erythroid cells in human cord blood cells. Mechanistically, ERG antagonizes KLF1 and inhibits erythroid maturation, whereas TP53 deficiency promotes proliferation of erythroid progenitors. Furthermore, we identified HDAC7 as a specific susceptibility in AEL by the DepMap-based two-group comparison analysis. HDAC7 promotes the growth of human and mouse AEL cells both in vitro and in vivo through its non-enzymatic functions. Our study provides experimental evidence that TP53 deficiency and ERG overexpression are necessary and sufficient for the development of AEL and highlights HDAC7 as a promising therapeutic target for this disease., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Decitabine (DAC) is clinically used to treat myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Our genome-wide CRISPR-dCas9 activation screen using MDS-derived AML cells indicates that mitotic regulation is critical for DAC resistance. DAC strongly induces abnormal mitosis (abscission failure or tripolar mitosis) in human myeloid tumors at clinical concentrations, especially in those with TP53 mutations or antecedent hematological disorders. This DAC-induced mitotic disruption and apoptosis are significantly attenuated in DNMT1-depleted cells. In contrast, overexpression of Dnmt1, but not the catalytically inactive mutant, enhances DAC-induced mitotic defects in myeloid tumors. We also demonstrate that DAC-induced mitotic disruption is enhanced by pharmacological inhibition of the ATR-CLSPN-CHK1 pathway. These data challenge the current assumption that DAC inhibits leukemogenesis through DNMT1 inhibition and subsequent DNA hypomethylation and highlight the potent activity of DAC to disrupt mitosis through aberrant DNMT1-DNA covalent bonds., Competing Interests: Declaration of interests The authors declare no potential conflicts of interest., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background/aim: Although computed tomography (CT) is the standard modality for diagnosing lymph node metastasis (LNM), transabdominal ultrasonography (US) can be useful due to its high spatial resolution and use of Doppler signals to precisely analyse lymph nodes. This study aimed to evaluate the accuracy of US for lymph node assessment, establish US-based diagnostic criteria for LNM, and compare the capability of US with that of CT for the diagnosis of LNM., Patients and Methods: This retrospective, single-institution, cohort study included patients who underwent radical surgery for clinical stage 0-III colon cancer, between March 2012 and February 2019., Results: Overall, 34.9% (66/189) of patients had pathological LNM. The optimal US diagnostic criteria were 1) short axis ≥7 mm and short/long ratio ≥0.75 and 2) at least two of the following: the absence of hilar echoes, expansive appearance, or peripheral/mixed vascularity by the colour Doppler and/or contrast-enhanced method. Compared to CT, US showed a higher diagnostic sensitivity (54.5% vs. 43.9%; p=0.296), higher concordance with the number of pathological LNM (correlation coefficient: US, 0.42; CT, 0.27) and pathological N diagnosis (weighted ĸ: US, 0.35; CT, 0.18), and higher sensitivity for advanced LNM, including multiple LNMs (47.4% vs. 18.4%; p=0.014) and N2 stage (27.8% vs. 5.6%; p=0.177)., Conclusion: US has higher sensitivity than CT for diagnosing LNM in colon cancer, along with a more accurate preoperative diagnosis of the N stage. Additionally, US may be more helpful than CT alone for preoperatively deciding the appropriateness of neoadjuvant treatment in colon cancer with advanced LNM., Competing Interests: The Authors have no conflicts of interest directly relevant to the content of this article., (Copyright 2022, International Institute of Anticancer Research.)

Polytetrafluoroethylene (PTFE) fine powder with 93% crystallinity was irradiated by an electron beam (EB) at various temperatures under a nitrogen atmosphere. Trapped free radicals in PTFE were studied using electron spin resonance (ESR) spectroscopy. The observed spectra of the samples exposed to air after irradiation at various temperatures showed asymmetrical signals, which are middle-chain type peroxide macroradicals derived from fluoroalkyl radicals. The radical yields at each irradiation temperature increased with increasing absorbed dose, and eventually saturated. The higher irradiation temperature resulted in higher radical yields when compared at the same exposed dose. Furthermore, the G-value of the radicals (G(R·)) increases with increasing irradiation temperatures corresponding to each relaxation and transition temperature. It is concluded that the chain reaction by the fluorine extraction from the main chain due to the end-chain radical generated via β-scission after dissociative electron attachment (DEA) is enhanced by the synergistic effect of heat and radiation.

A new sustainable synthetic method for cellulose acetate was developed by a combination of I 2 -catalyzed solid-liquid acetylation of cellulose and a milling process reducing the crystallinity of cellulose within a few seconds. Milled low-crystalline cellulose was acetylated faster than the original cellulose with higher crystallinity. The plausible factors of acceleration were the conversion of the hydroxy group in hydrogen bonds into reactive ones and the efficient formation of the catalytic species I + by the enhanced formation of I 3 - assisted by the amorphous domain of the milled cellulose, while the morphological and structural changes were ignorable., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

Introduction: Blakiston's fish owl (Bubo blakistoni) was previously widespread on Hokkaido Island, Japan, but is now distributed only in limited forest areas. The population size on Hokkaido decreased during the 20th century due to reduction and fragmentation of the owl's habitat. To elucidate temporal and spatial changes in population structure and genetic diversity, we analyzed 439 individuals collected over the last 100 years., Results: We detected a population bottleneck and fragmentation event indicated by mitochondrial DNA (mtDNA) haplotype and microsatellite analyses. The lowest value for effective population size, which was estimated by moment and temporal methods from microsatellite data, occurred in the 1980s. Five haplotypes were found in the mtDNA control region; most haplotypes were previously widespread across Hokkaido, but have become fixed in separate areas after the bottleneck period. Genetic differentiation among local populations, as indicated by both mtDNA and microsatellite data, likely arose through population fragmentation., Conclusions: The owl population may have been divided into limited areas due to loss of habitats via human activities, and have lost genetic variability within the local populations through inbreeding. Our mtDNA and microsatellite data show that genetic diversity decreased in local populations, indicating the importance of individuals moving between areas for conservation of this species on Hokkaido.

Red-crowned cranes (Grus japonensis) are distributed separately in the east Eurasian Continent (continental population) and in Hokkaido, Japan (island population). The island population is sedentary in eastern Hokkaido and has increased from a very small number of cranes to over 1,300, thus giving rise to the problem of poor genetic diversity. While, Hooded cranes (Grus monacha), which migrate from the east Eurasian Continent and winter mainly in Izumi, Kagoshima Prefecture, Japan, are about eight-time larger than the island population of Red-crowned cranes. We collected whole bodies of these two species, found dead or moribund in eastern Hokkaido and in Izumi, and observed skeletons with focus on vertebral formula. Numbers of cervical vertebrae (Cs), thoracic vertebrae (Ts), vertebrae composing the synsacrum (Sa) and free coccygeal vertebrae (free Cos) in 22 Red-crowned cranes were 17 or 18, 9-11, 13 or 14 and 7 or 8, respectively. Total number of vertebrae was 47, 48 or 49, and the vertebral formula was divided into three types including 9 sub-types. Numbers of Cs, Ts, vertebrae composing the Sa and free Cos in 25 Hooded cranes were 17 or 18, 9 or 10, 12-14 and 6-8, respectively. Total number of vertebrae was 46, 47, 48 or 49, and the vertebral formula was divided into four types including 14 sub-types. Our findings clearly showed various numerical vertebral patterns in both crane species; however, these variations in the vertebral formula may be unrelated to the genetic diversity.

The present study investigated a novel method for producing amorphous cellulose by milling without adding water. A new type of milling machine was developed (called a shear and cooling milling machine (SCMM)), which was capable of applying mechanical shear and cooling during the milling process. The SCMM consisted of a pair of mortars attached to a servomotor and a ring cooler. Wide-angle X-ray diffraction (WAXD) analysis was used to determine the cellulose crystallinity in samples produced using the SCMM at different milling temperatures. The results of WAXD for cellulose powder milled at lower temperatures exhibited no diffraction peaks. This experimental result demonstrates that the SCMM produces amorphous cellulose easily by cooled milling without the addition of water. The milling conditions, such as the applied shear and cooling, can be used to control the crystallinity of cellulose., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A 33 month-old male flying squirrel kept in a zoo developed progressive dyspnea and died. Macroscopically, the liver and lung were enlarged with numerous nodular vesicles. Histologically, these organs were replaced by numerous collapsed vesicles demarcated by fibrous tissues. The cysts lined by a cellular, germinal layer contained numerous brood capsules with abundant production of well-developed protoscolices. Protoscolices were about 80-100 μm in diameter, and had hooks being visible as refractive structures. This zoo locates in the east of Hokkaido where is an endemic area of Echinococcus multilocularis infection. From epidemiology and pathological findings, this animal was diagnosed as E.multilocularis infection. This report describes the pathology of the first case of E. multilocularis infection in a flying squirrel.

A 33-year-old red-crowned crane (Grus japonensis) had a diffuse intestinal thickening from the duodenum to colon. Microscopically, neoplastic cells were arranged in sheets and occasionally nests or cords without gland or squamous differentiation. Metastatic tumor cells were found in the lungs, heart, kidneys and adrenal glands. Immunohistochemically, the neoplastic cells were strongly positive for pan-cytokeratin and cytokeratin 8 and 18 and only partly positive for E-cadherin antibodies. Immunostaining for CD3 was positive in normal lymphocytes, and NSE was also positive in normal nerve fibers. But, the neoplastic cells were not immunoreactive to CD3 and NSE. Based on the histological features and the epithelial characteristics in the immunohistochemical stain, the present case was diagnosed as undifferentiated carcinoma originating from the intestine. Interestingly, the neoplastic cells showed a unique growth pattern; they never invaded the submucosa or muscularis throughout the intestine, whereas they spread lymphogenously or hematogenously to other organs.

Red-crowned (or Japanese) cranes Grus japonensis are native to eastern Hokkaido, Japan--the island population, and mainland Asia--the continental population that migrates from breeding grounds along the Amur River Basin to winter in east China and the Korean Peninsula. The island population was reduced to about 50-60 birds in early part of the 20th century. Since 1950s, the population has increased to more than 1,300 as a consequence of human-provided food in winter, resulted in change of their habitats and food resource. From the carcasses of 284 wild cranes from the island population, collected in Hokkaido since 1976 until 2010, we measured six physical parameters (body weight and lengths of body, wing, tarsus, tail and exposed culmen) and divided into groups by sex and three developmental stages (juvenile, yearling and adult). All parameters of males were larger than those of females at the same stage. Total body length of females tends to grow up earlier than males, in contrast to body weight. Obvious time trends were not observed in these all parameters during 34 years for these six categories measured, except total length of male juveniles, which showed a significant increasing trend. These results provide the first extensive data on body size and mass in the wild red-crowned cranes.

Red-crowned cranes (Grus japonensis) are native to eastern Hokkaido (island population), in contrast to the mainland, which migrates between the Amur River basin and eastern China-Korea peninsula. During the 1990s we found that Red-crowned cranes in Hokkaido were highly contaminated with mercury: however, the source was unknown. We investigated the time trend of mercury contamination in Red-crowned cranes. Total mercury levels in the livers and kidneys from cranes dead in the 2000s were lower than those dead in the 1990s. Feather is a major pathway of mercury excretion for many bird species and is used as an indicator of blood mercury level during feather growth. As internal organs from the specimens collected before 1988 were not available, we analyzed the flight feather shavings from stuffed Red-crowned cranes dead in 1959-1987 and found that the mercury level of feathers from cranes dead in the 1960s and 1970s was not more than those from the cranes dead in the 2000s. These results suggest that mercury contamination in Red-crowned cranes in Hokkaido decreased temporally during the 1990s-2000s. This indicates the possible occurrence of some mercury pollution in Red-crowned cranes' habitat in this region in the 1990s or before.

Purpose: To observe the current situation of tuberculosis and its control measures in hemodialysis facilities in Chiba Prefecture, Japan., Method: Questionnaires on medical dialysis and tuberculosis were sent to hemodialysis facilities in Chiba Prefecture., Results: The questionnaires were answered by 55 of 127 facilities. Of the respondents, 46 (83.6%) were not aware of the recommendation of treatment for latent tuberculosis infections in Japanese patients. Moreover, 30 (54.5%) facilities did not examine patients for tuberculosis prior to the initiation of hemodialysis. Of the 21 facilities that did assess patients for tuberculosis infection, only 5 (23.8%) performed a tuberculin skin test or QuantiFERON TB-2G. Three of the five (60.0%) that were treating tuberculosis by themselves expressed fear or uncertainty about the diagnosis and treatment of latent tuberculosis infections. During January 2006 through December 2007, tuberculosis patients were detected in 11 facilities, and the proportion of extrapulmonary tuberculosis among these patients was 52.4%. Seven facilities reported that they took no control measures against tuberculosis., Conclusion: It is important to inform medical dialysis facilities about latent tuberculosis infections, the early diagnosis of tuberculosis, and the combination of nosocomial infection control. It is also important for experts in hemodialysis and tuberculosis to work closely together.

Purpose: To examine the clinical problems of died cases with pulmonary tuberculosis., Methods: Clinical findings of 52 patients with active pulmonary tuberculosis, who had died in our hospital between April 2005 to March 2007, were analyzed., Results: Mean age was 72.3 10.6 years old, 9 cases (17.3 %) were relapsed, and 35 cases (67.3%) had cavity on the chest X-ray. 34 cases (65.4%) were PS4 and none was PS0 or PS1 on admission. Complications were malignancy in 11 cases, diabetes mellitus in 10 cases, and respiratory diseases in 6 cases. 15 cases (28.8%) were treated with drugs including INH, RFP and PZA, 14 cases (26.9%) with drugs including INH and RFP, 16 cases (30.8%) with the other drugs, and 7 cases (13.5%) were not able to be administered any drug. 35 cases (67.3%) died of tuberculosis and 17 cases (32.7%) died of non-tuberculous conditions., Conclusion: Many died cases were under very poor general condition, needed frequent care, had many kind of complications and had difficulty with standard treatment on admission. Tuberculous death were observed highly, but death by complications were observed in many cases. It is necessary to control complications and enlighten society and docters about importance of early diagnosis and treatment of tuberculosis continuously.

Aim: We aimed to assess the efficacy and safety of midtrimester termination of pregnancy using gemeprost in combination with laminaria in women who had previously undergone cesarean section and in women who had not., Methods: Between January 1999 and December 2006, we carried out a retrospective study of termination of pregnancy at 12-21 weeks of gestation at the University of Tsukuba Hospital. Termination of pregnancy was carried out by three-step uterine cervical dilation using laminaria followed by vaginal administration of 1 mg gemeprost every 3 h for up to four doses over 24 h., Results: A total of 173 women underwent midtrimester termination of pregnancy. The women were categorized into two groups: those who had previously undergone cesarean section (n = 26) (previous cesarean section group) and those who had not (n = 147) (control group). Seven women had undergone cesarean section at least twice. The gemeprost dose administered was 2.8 +/- 1.4 mg for the previous cesarean section group and 2.4 +/- 1.6 mg for the control group (difference in doses not significant). Although abnormal vaginal bleeding (>500 mL) was more likely to occur in the previous cesarean section group than in the control group (odds ratio, 2.61; 95% confidence interval, 0.63-10.82), none of the woman required blood transfusion. Uterine rupture and failed abortion were not observed., Conclusion: The efficacy and safety of our laminaria-gemeprost protocol for termination of pregnancy during the midtrimester are similar for women who have previously undergone cesarean section and those who have not.

A 79-year-old man with past history of thoracoplasty due to pulmonary tuberculosis visited a general clinic complaining of left back pain and left axillary tumor. As the pus of tumor aspirated was positive for PCR-TB, the patient was diagnosed as pericostal tuberculosis and introduced to our hospital. At first, the operation was considered, but the patient had high risk for the operation because he was old and low body weight and the lesion of tuberculosis in his thorax was very extensive. Anti-tuberculous drugs were administrated and exclusion of pus by needle aspiration was repeated. After starting the treatment, the size of tumor had reduced guradually. Pericostal tuberculosis should be taken into consideration in case of pericostal mass with past history of tuberculosis, and the method of treatment should be decided with considering patient's condition.

Background: Angiotensin-converting enzyme (ACE) plays an important role in vascular remodeling in pulmonary hypertension, and ACE gene polymorphism is associated with exercise-induced pulmonary hypertension in Japanese patients with chronic obstructive pulmonary disease. The present study was designed to investigate if ACE-insertion (I)/deletion (D) polymorphism might be related to the susceptibility, severity, and disease outcome in chronic thromboembolic pulmonary hypertension (CTEPH)., Methods and Results: ACE-I/D genotypes were determined in 95 consecutive CTEPH patients (46 underwent surgery, 49 received medical treatment) and 97 controls. The frequencies of genotypes and alleles were not significantly different between patients and controls. Clinical characteristics were compared among ACE genotypes (II, ID, DD). ACE D allele carrier (ID plus DD) was associated with a lower 6-min walk test distance compared with D allele non-carrier (II) (330+/-102 (mean +/- SD) vs 381 +/-85 m, p=0.046). Kaplan-Meier analysis in the medically treated group showed significantly deteriorated survival for D allele carriers compared with D allele non-carriers (p=0.0389). Multivariate analysis revealed that age (p=0.013), pulmonary vascular resistance (p=0.008), and D allele carrier status (p=0.021) were independent predictors of survival., Conclusion: ACE D allele carrier is possibly one of the prognostic factors for medically treated CTEPH patients.

Purpose: Recently, the application of replication-competent viruses has been studied as anticancer agents. Sindbis virus (SIN) is an RNA virus that belongs to the Alphavirus genus in the Togaviridae virus family. The AR339 strain of SIN has not been reported to induce any serious disease to humans., Experimental Design: In this study, we evaluated the feasibility of the replication-competent SIN AR339 strain as an agent for cervical and ovarian cancer therapy., Results: SIN infection was able to induce cytopathic effects and apoptosis in two cervical cancer cells (HeLaS3 and C33A) and three ovarian cancer cells (HOC-1, HAC-2, and OMC-3) but not in normal human keratinocytes in vitro. The analysis of cell viability, virus protein synthesis, and viral growth showed the cancer-specific cytotoxicity and virus growth of SIN. In nude mice, i.t. and i.v. inoculation of SIN resulted in significant regression of established cervical tumors implanted at their backs. Histologic studies revealed that systemic treatment with the single injection of SIN induces necrosis within tumors at a remote site. In the metastasis model of ovarian cancer, suppression of ascites formation was observed in nude mice with i.p. SIN treatment. By using an in vivo green fluorescent protein imaging system, we also showed that systemic treatment with SIN targeted tumors specifically., Conclusions: Our study suggested that SIN AR339 strain has a possibility as a novel agent for human cervical and ovarian cancer therapy.

This study evaluated the influence of curing method and storage condition on the microhardness of dual-cure resin cements: Panavia F 2.0 (PF) and Nexus 2 (NX). The specimens were either light-cured (LC) or chemically cured in darkness (CC). After 24 hours of storage in dry chamber (Dry) or distilled water (DW), the specimens were sectioned and polished. The microhardness of resin cement matrix was measured using a nanoindentation tester (ENT-1100). The data (n = 6) were statistically analyzed with t-test, two-way ANOVA (p < 0.05), and Tukey HSD test (alpha = .05). It was found that the factors of curing method and storage condition had significant effect on microhardness. For both PF and NX, LC presented higher microhardness than CC, while DW showed higher microhardness than Dry. In conclusion, dual-cure resin cements could achieve high degree of cure when light-cured. In addition, the microhardness of the resin cements evaluated did not decrease when kept in water.

Background: Obesity and visceral fat accumulation (VFA) are risk factors for the development of obstructive sleep apnea-hypopnea syndrome (OSAHS), and a subgroup of OSAHS patients acquire hypoventilation. Circulating leptin, an adipocyte-derived signaling factor, increases in accordance with body mass index (BMI); under experimental conditions, leptin selectively decreases visceral adiposity and it is also a respiratory stimulant., Objective: To investigate whether the location of body fat deposits, ie, the distribution of VFA and subcutaneous fat accumulation (SFA), contributes to hypoventilation and whether circulating levels of leptin are involved in the pathogenesis of hypoventilation, which is often observed in OSAHS., Methods: We assessed VFA and SFA by abdominal CT scan, and measured lung function and circulating levels of leptin in 106 eucapnic and 79 hypercapnic male patients with OSAHS., Results: In the whole study group, circulating leptin levels correlated with BMI (r = 0.56), VFA (r = 0.24), and SFA (r = 0.47), but not with Po(2) or sleep mean arterial oxygen saturation (Sao(2)). BMI, percentage of predicted vital capacity, FEV(1)/FVC ratio, apnea-hypopnea index, sleep mean Sao(2), VFA, and SFA were not significantly different between two groups. Circulating leptin levels were higher in the hypercapnic group than in the eucapnic group. Logistic regression analysis indicated that serum leptin was the only predictor for the presence of hypercapnia (beta = 0.21, p < 0.01)., Conclusions: These results suggest that the location of body fat deposits may not contribute to the pathogenesis of hypoventilation, and circulating leptin may fail to maintain alveolar ventilation in hypercapnic patients with OSAHS.

Histological survey was made to determine nitrate toxicity on the Medaka fish, Oryzias latipes. In order to investigate the effects of short-term exposure to nitrate, one-month-old Medaka fish was exposed to NaNO3 at concentrations of 100 and 125 mg NO3-N l-1 for 96 hours. At the end of the exposure period, survival rate was found to be 30% and 10%, for the 100 and 125 mg NO3-N l-1 exposure concentrations, respectively. Histological examination of the organs showed that disruption of cell alignment was a common feature in the gills, intestinal ampulla, liver and kidney. A long-term exposure experiment was also carried out, whereby Medaka fish was exposed to NaNO3 (100 and 125 mg NO3-N l-1) for three months from its egg stage. Eggs treated with NaNO3 hatched within 10 days after fertilization. At the end of the exposure period, survival rate in the 100 and 125 mg NO3-N l-1 treatments were 40% and 30%, respectively. Fibrosis of the hepatic cells and curved spinal column were observed in the juveniles subjected to long-term nitrate exposure. The results of our experiments suggest that the high mortality resulting from short-term acute exposure to nitrate is caused by general dysfunction throughout the whole body. The chronic toxic effects attributed to nitrate, following long-term exposure, were likely to have resulted from nutrient deficiency caused by hepatic dysfunction.

A 71-year-old man was admitted to our hospital because of systemic edema and exertional dyspnea. Chest radiographs revealed infiltrative shadows in both lung fields, pleural effusion, and pericardial effusion. Seven years before, he had undergone gastric surgery for a gastric ulcer with lymphoid hyperplasia. In the pathologic diagnosis based on the percutaneous lung biopsy, hyalinizing granuloma was suspected. For a more thorough diagnosis, the patient was subjected to an open lung biopsy, and the final diagnosis was low-grade B-cell lymphoma of the MALT (mucosa-associated lymphoid tissue) type. Gallium scintigraphy showed accentuated accumulation in the left neck and hypothyroidism was present. Histologic re-examination of the resected stomach revealed infiltration of centrocyte-like cells and lymphoepithelial lesions, compatible with the pathologic features of MALT lymphoma. We considered that the gastric neoplasm and the pulmonary, pleural, and thyroid tumors of MALT lymphoma had occurred seven years apart in this case. Thyroid hormone replacement and CHOP therapy improved the symptoms and decreased the lung tumor size by 73%. MALT lymphomas tend to remain localized for a long period. The multiorgan involvement seen in this case is rather rare.

Since a biological filter with nitrifying bacteria was firstly applied to aquatic animal experiments in IML-2 mission, the reactor system has been further studied to combine both nitrifying and denitrifying reactions under aerobic environment allowing an efficient removal of inorganic nitrogen from animal wastes. The isolated denitrifying bacteria had an activity under aerobic condition with rice straw providing a metabolic carbon source for the reaction. The advantage of the aerobic biological filter having both nitrifying and denitrifying activities may allow to reduce the size of the life support system and also for its manageability. The paper reports characteristics of the biological filter systems used for the IML-2 mission and the improved combined filter system having both nitrifying and denitrifying activities, and discuss its application to space experiments.

In a space environment such as Space Shuttle or Space Station, animal experiments with aquatic species in a closed system pose a crucial problem in maintaining their water quality for a long term. In nature, ammonia as an animal wastes is converted by nitrifying bacteria to nitrite or nitrate compounds, which usually become nitrogen sources for plants. Thus an application of the biological reactor with such bacteria attached on some filters has been suggested and experimentally studied for efficient waste managements of ammonia. Although some successful results were reported (Kozu et al. 1995, Nagaoka et al. 1998, Nakamura et al. 1997, 1998) in the space applications, purely empirical approaches have so far been taken to develop a biological filter having a stable nitrifying activity. In this study, we constructed a mathematical model to deal with the dynamics of the ammonia nitrifying processes in a biological reactor. The model describes population dynamics of the ammonia-oxidizing bacteria and the nitrite-oxidizing bacteria cultivated on the same filter. We estimated parameters involved in the model using the experimental data. The result shows that these estimated parameters could be applied to general cases and that the two bacteria are in a symbiotic relationship; they can better perform when both coexist, as has been empirically recognized. Based on the model analysis, we discuss how to prepare a high performance biological filter.

The feasibility of intracellular recordings under constraints for experimental conditions in outer space were tested at a telescience testbed of the National Space Development Agency of Japan. We attempted to study the dose-response relationship of adenosine-induced potential changes in the Xenopus oocyte. The testbed simulated the distance from a ground control room to oocytes in an orbital laboratory; signals were delayed and compressed from one "station" to other. A microelectrode was inserted into the oocyte using remote control on the manipulator and on the xyz-planes of the platform with stereoscopic pictures observed through a head mounted display. When the transfer rate of the visual signals was decreased from 1.5 Mbps to 128 Kbps, insertion of the electrode became almost impossible because of reduced picture quality. Once the electrode was inserted, however, dose-dependent adenosine responses could be observed with little trouble.