Biomedical subjects

S Uchida

Publications and source records attributed to S Uchida.

At least 163 records · Page 9Linked to original sources

PubMed1999

Enhanced gamma (30-150 Hz) frequency in the human medial temporal lobe.

We performed fast Fourier transformation power spectral analysis of the electrocorticogram in human medial temporal lobe during wakeful rest in six epileptic subjects. Compared with the electrocorticogram wave in the basal temporal lobe, which showed monotonic decline of spectral power across the frequency axis, the electrocorticogram wave in the parahippocampal gyrus was enhanced (or did not decline) in the gamma frequency range (30-150 Hz) in all subjects. Although it has been suggested that electrical oscillations of the hippocampus have functional roles in higher brain functions, namely learning and memory, the knowledge of hippocampal oscillations is largely limited to animal studies. The present results demonstrate that fast frequency oscillation is also present in the human medial temporal lobe, which has been reported in animal hippocampi. They also demonstrate the importance of recording very fast field potentials in human electrocorticograms. This fast oscillation is likely to play important functional roles related to learning and memory, possibly to induce long-term potentiation in the human medial temporal lobe.

Action Potentials↗

PubMed1999

Laparoscopic ultrasonography versus operative cholangiography during laparoscopic cholecystectomy: review of the literature and a comparison with open intraoperative ultrasonography.

BACKGROUND: Laparoscopic ultrasonography (LUS) has been used increasingly over the last several years as a new imaging modality. To define the role of LUS during laparoscopic cholecystectomy, we evaluated LUS by prospectively comparing it with operative cholangiography (OC), by reviewing the literature on LUS, and by retrospectively comparing it with intraoperative ultrasonography performed during open cholecystectomy. STUDY DESIGN: LUS and OC were compared prospectively in 100 consecutive patients during laparoscopic cholecystectomy. The success rate of examination, the time required, the accuracy in diagnosing bile duct calculi, and the delineation of biliary anatomy were evaluated. RESULTS: The success rate of examination was 95% for LUS and 92% for OC. The main reason for unsatisfactory LUS was incomplete visualization of the distal common bile duct. The time required was 8.2 minutes for LUS and 15.9 minutes for OC (p<0.0001). Nine patients had bile duct calculi. LUS had one false-negative result and OC had two false-positives and one false-negative. The accuracies of LUS and OC were comparable except for a slightly better positive predictive value of LUS (100% versus 77.8%; p>0.1). In a literature review, 12 recent prospective studies comparing LUS and OC and three studies on open intraoperative ultrasonography were reviewed. Twelve studies of LUS with a total of 2,059 patients demonstrated results similar to the present study. The success rate was 88% to 100% for both tests. The time for LUS was approximately 7 minutes, about half of the time needed for OC. Overall, LUS was associated with fewer false-positive results than OC; the positive predictive value and specificity of LUS were better, while the sensitivity and negative predictive value of LUS and OC were comparable. OC detected ductal variations or anomalies more distinctly than LUS. Compared with open intraoperative ultrasonography, LUS had a slightly lower success rate and required a slightly longer time because it was technically more demanding, but the two procedures had a similar accuracy for diagnosing bile duct calculi. CONCLUSIONS: Because of their different advantages and disadvantages, LUS and OC can be used in a complementary manner. There is a learning curve for LUS because of its technical difficulty. Once learned, however, LUS can be used as the primary screening procedure for bile duct calculi because of its safety, speed, and cost-effectiveness. OC can be used selectively, particularly when ductal anatomic variations or anomalies or bile duct injuries are suspected.

Cholangiography↗

PubMed1999

Overt nephrogenic diabetes insipidus in mice lacking the CLC-K1 chloride channel.

CLC-K1 is a kidney-specific chloride channel that mediates transepithelial chloride transport in the thin ascending limb of Henle's loop (tAL) in the inner medulla. Transport of NaCl in the tAL is thought to be a component of urinary concentration in a passive model of the countercurrent multiplication system, but there has been no direct evidence that CLC-K1 is involved in urine concentration. To analyse the physiological function of CLC-K1 in vivo, we generated mice lacking CLC-K1 by targeted gene disruption. Clcnk1-/- mice were physically normal appearance, but produced approximately five times more urine than Clcnk1+/- and Clcnk1+/+ mice. After 24 hours of water deprivation, Clcnk1-/- mice were severely dehydrated and lethargic, with a decrease of approximately 27% in body weight. Intraperitoneal injection of the V2 agonist 1-deamino-8-D-arginine vasopressin (dDAVP) induced a threefold increase in urine osmolarity in Clcnk1+/- and Clcnk1+/+ mice, whereas only a minimal increase was seen in Clcnk1-/- mice, indicating nephrogenic diabetes insipidus. After in vitro perfusion of the tAL, the lumen-to-bath chloride gradient did not produce a diffusion potential in Clcnk1-/- mice in contrast to Clcnk1+/+ and Clcnk1+/- mice. These results establish that CLC-K1 has a role in urine concentration, and that the countercurrent system in the inner medulla is involved in the generation and maintenance of hypertonic medullary interstitium.

Animals↗

PubMed1999

Motility-related protein (MRP-1/CD9) and KAI1/CD82 expression inversely correlate with lymph node metastasis in oesophageal squamous cell carcinoma.

Although the mechanisms of action of the transmembrane superfamilies, motility-related protein-1 (MRP-1/CD9) and KAI1/CD82, are not well known, they are reported to suppress the metastasis of several kinds of cancers. The suppression of cell motility by MRP-1/CD9 may cause suppression of the metastasis. As we could not find any reports concerning the expression of MRP-1/CD9 and KAI1/CD82 in oesophageal cancers we investigated their expression in oesophageal specimens. We conducted immunohistochemical staining for MRP1/CD9 against 108 cases of oesophageal squamous cell carcinoma using anti-MRP-1/CD9 monoclonal antibody M31-15, and for KAI1/CD82 against 104 cases using anti-KAI1/CD82 monoclonal antibody C33. To investigate the gradual expression of MRP-1/CD9 and KAI1/CD82, 24 oesophageal dysplasias were immunohistochemically stained using the same method and then investigated. The expression of both MRP-1/CD9 and KAI1/CD82 were positive on the cell membranes of normal oesophageal epithelial cells, but reduced or negative in the cancer cells. Reduced MRP-1/CD9 expressions significantly correlated to tumour depth (P = 0.0009). We found a significantly greater number of reduced or negative expression of MRP-1/CD9 and KAI1/CD82 in lymph node metastatic cases (P = 0.0003 and P= 0.0129, respectively), but not in distant metastatic cases. The 5-year survival rate of MRP-1/CD9-negative and reduced patients was significantly worse than those of positive patients (n = 108, curative cases, RO). Few cases remained KAI1/CD82-positive (9.6%; 10/104) in oesophageal cancer. Twenty (83.3%) and twenty-two (91.7%) cases out of 24 dysplasias were defined as KAI1/CD82-positive and MRP1/CD9-positive, respectively. The decrease in MRP-1/CD9 and KAI1/CD82 expression may facilitate lymph node metastasis in oesophageal squamous cell carcinomas. Knowing the status of the expression of MRP-1/CD9 appears helpful in predicting the prognosis for each patient.

Adult↗

PubMed1999

Expression of vascular endothelial growth factor, matrix metalloproteinase-9 and E-cadherin in the process of lymph node metastasis in oesophageal cancer.

Lymph node metastasis is a strong independent prognostic factor for oesophageal cancer. The expression of matrix metalloproteinases (MMPs) and reduction of E-cadherin correlate with lymph node metastasis of oesophageal cancer. We previously reported that the expression of vascular endothelial growth factor (VEGF) is associated with lymph node metastasis. This study was designed to determine whether VEGF, MMP-9 and E-cadherin expression is stable or changes in the process of lymph node metastasis of oesophageal cancer. Using immunohistochemistry, we detected VEGF, MMP-9 and E-cadherin expression in paraffin-embedded specimens of oesophageal squamous cell carcinoma. We classified 134 primary tumours and 174 nodal metastases using two different criteria: the absence [Group N(-)] or presence [Group N(+)] of nodal metastasis, and the stage of metastasis--Early Stage (cancer cells < 50% of lymph node) or Late Stage (> or = 50%)--and compared the expression among two groups and among two stages. The expression rates of Group N(-), Group N(+), Early Stage and Late Stage are as follows: VEGF (49%, 74%, 60%, 33%), MMP-9 (76%, 65%, 95%, 69%) and E-cadherin (49%, 24%, 55%, 38%). VEGF expression was down-regulated in Late Stage lymph node metastasis, while MMP-9 expression was elevated in Early Stage metastasis. E-cadherin expression is restored somewhat in Early Stage metastasis, but suppressed again in Late Stage metastasis. These data suggest that the expression of VEGF, MMP-9 and E-cadherin each change in the process of lymph node metastasis in oesophageal cancer, and that the patterns of change are different.

Adult↗

PubMed1999

Prognostic factors of oesophageal squamous cell carcinoma from the perspective of molecular biology.

Recent developments in molecular biology have revealed that several oncogenes, suppressor genes and adhesion molecules are involved in the development of oesophageal cancer; however, the role of these genes is still unknown. To evaluate which molecular biological factors are related to patients' prognosis and recurrence, we checked p53, p16, p21/Waf1, cyclin D1, Ki-67, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), Mdm2, Bcl2, E-cadherin and MRP1/CD9 by means of immunohistochemical analysis in 116 cases of oesophageal cancer (R0). We also checked the regrowth capability of the primary cultures of the resected tumours and the effect of post-operative treatment. Although univariate analysis revealed that pN (pTNM), pT (pTNM), sex, cyclin D1, Ki-67, VEGF, E-cadherin and cell regrowth capability were prognostic factors, multivariate analysis revealed that pN (risk ratio (RR) 3.17), sex (RR 8.13), cell regrowth capability (RR 3.03) and E-cadherin (RR 0.30) were prognostic factors. Interestingly, step-wise analysis revealed that the following five factors were prognostic factors: pN (RR 5.74), sex (RR 3.14), cyclin D1 (RR 2.29), E-cadherin (RR 0.26) and cell regrowth capability (RR 1.94). Logistic regression analysis revealed that the risk factors of haematogenous recurrence were pN (odds ratio (OR) 8.97), cyclin D1 (OR 4.52) and EGFR (OR 0.18). On the other hand, the risk factor of lymph node recurrence was pN (OR 5.16). With regard to the effect of postoperative treatment, post-operative radiotherapy was a favourable risk factor (RR 0.43) and reduced the haematogenous recurrence (OR 0.18). Our data indicate that combination analysis using pN, sex, cyclin D1, E-cadherin, EGFR and cell regrowth capability may be useful for the prediction of patient survival and recurrence.

Aged↗

PubMed1999

Acute myocardial infarction following toxic epidermal necrolysis?

We describe a 29-year-old woman with rheumatoid arthritis who suffered an acute myocardial infarction 70 days after an initial presentation with toxic epidermal necrolysis (TEN). The trigger for the TEN was probably an over-the-counter anti-influenza treatment containing tipepidine hibenzate. Although the patient had familial hypercholesterolemia, we believe that thrombocytosis, induced by the inflammatory response and metabolic stress resulting from the TEN, may also have played a significant role in the pathogenesis of the myocardial infarction. Although TEN manifests itself principally as a skin disease, the potential for systemic morbidity, including cardiovascular abnormalities, should also be remembered.

Adult↗

PubMed1999

Electromyographic study of the activity of jaw depressor muscles before initiation of opening movements.

The authors attempted to clarify the primary factors affecting the timing of the initial electromyographic discharges in the jaw depressor muscles (EMG onset). The changes in EMG onset in the inferior head of the lateral pterygoid (Lpt) and the anterior belly of the digastric muscles (Dig) were measured by varying duration of the open-close movement or occlusal force during the open-close-clench cycle (OCC). EMG onset tended to precede the beginning of the opening movement during OCC. The duration of opening and closing phase and the duration of occluding phase showed no significant correlation with the time-lag between EMG onset and the beginning of the opening movement (onset time). The mean EMG activity of the masseter muscle (Mm), corresponding to the occlusal force, showed a highly significant correlation with the onset time. The maximal opening velocity was highly correlated with the mean EMG activity of the jaw depressors before jaw opening. In conclusion, it was found that occlusal force is a major factor in EMG onset in the jaw depressors. It is suggested that smooth opening needs tooth contact with some degree of occlusal force.

Adult↗

PubMed1999

Cloning and functional expression of rAOP9L a new member of aquaporin family from rat liver.

A new aquaporin was isolated from rat liver based on homology to known aquaporins. A 1408 bp cDNA was sequenced (designated rAQP9L) with a 885 bp open reading frame encoding a 295 amino acid hydrophobic protein. rAQP9L has the greatest amino-acid sequence identity with human AQP9 (75%) and a less homology with AQP3 (49%) and AQP7 (47%). Northern blot analysis indicated a 1.4-kb transcript expressed strongly in liver > testis > brain = lung. Expression of rAQP9L cRNA in Xenopus oocytes increased osmotic water permeability by 6-folds which was inhibited by 0.3 mM mercury chloride by 42%. rAQP9L also facilitated glycerol and urea transport by 2- and 5-folds, respectively. The large discrepancy of tissue distribution between hAQP9 and rAQP9L suggest that rAQP9L is a new aquaporin, which is involved in transport of urea as well as water in liver.

Amino Acid Sequence↗

PubMed1999

Human parathyroid hormone (1-34) transiently increases the excretion of lysosomal enzymes into urine and the size of renal lysosomes.

It has been reported that the urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), a lysosomal enzyme, transiently increases in human after treatment with human parathyroid hormone (hPTH)(1-34). We report here that hPTH(1-34) caused transient changes in the size and density of rat renal lysosomes following urinary excretion of NAG and other lysosomal enzymes tested. Percoll density gradient centrifugation revealed that hPTH(1-34) slightly but significantly increased the fraction of high density lysosomes (around 1.12 g/ml) 5-10 min after the treatment with hPTH(1-34), with a concomitant decrease in the fraction of intermediate density lysosomes (1.07-1.08 g/ml). On electron micrographs, some lysosomes in proximal tubules but not in distal tubules showed a change in morphology from circular to oval, and became enlarged and electron-dense 5-10 min after the treatment with hPTH(1-34). These responses to hPTH(1-34) were also reversible and transient. NAG excreted in urine after treatment with hPTH(1-34) had the molecular mass of a mature form in lysosomes and/or endosomes and was not a prepro-and/or pro-form of the enzyme. Thus, the changes in the density and size of renal lysosomes appear to be associated with the exocytosis of lysosomal enzymes by hPTH(1-34).

Acetylglucosaminidase↗

PubMed1999

Involvement of fibroblast growth factor-2 in joint destruction of rheumatoid arthritis patients.

OBJECTIVE: To investigate the effect of the synovial fluid from knee joints of rheumatoid arthritis (RA) patients with different severities of joint destruction on osteoclastogenesis and bone resorption. METHODS: Synovial fluid was harvested from the knee joints of 59 RA patients and 37 ostcoarthritis (OA) patients. RA patients with Larsen's knee grade 1-3 were classified as mild RA (n = 30) and those with grade 4 or 5 as severe RA (n = 29). Cytokine concentrations in synovial fluid were measured by ELISA. Osteoclastogenesis was measured by tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cell (MNC) formation in a co-culture of mouse osteoblastic cells and bone marrow cells, and bone resorption by 45Ca release from pre-labelled cultured neonatal mouse calvariae. RESULTS: The synovial fluid of severe RA patients significantly stimulated TRAP-positive MNC formation and 45Ca release compared to those of mild RA and OA patients. Among the bone-resorptive cytokines fibroblast growth factor-2 (FGF-2), tumour necrosis factor alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), IL-6 and soluble IL-6 receptor (sIL-6R), only FGF-2 concentration in the synovial fluid was positively correlated to Larsen's grade, and severe RA patients showed significantly higher FGF-2 concentrations than mild RA patients. Osteoclastogenesis in a co-culture system which was stimulated by the synovial fluid of severe RA patients was significantly inhibited by a neutralizing antibody against FGF-2 and this inhibition was stronger than antibodies against other cytokines. CONCLUSION: The increase in endogenous FGF-2 levels in the synovial fluid of RA patients may play a role in the joint destruction by inducing osteoclastogenesis.

Animals↗

PubMed1999

Localization of rat CLC-K2 chloride channel mRNA in the kidney.

To gain insight into the physiological role of a kidney-specific chloride channel, CLC-K2, the exact intrarenal localization was determined by in situ hybridization. In contrast to the inner medullary localization of CLC-K1, the signal of CLC-K2 in our in situ hybridization study was highly evident in the superficial cortex, moderate in the outer medulla, and absent in the inner medulla. To identify the nephron segments where CLC-K2 mRNA was expressed, we performed in situ hybridization of CLC-K2 and immunohistochemistry of marker proteins (Na+/Ca2+ exchanger, Na+-Cl- cotransporter, aquaporin-2 water channel, and Tamm-Horsfall glycoprotein) in sequential sections of a rat kidney. Among the tubules of the superficial cortex, CLC-K2 mRNA was highly expressed in the distal convoluted tubules, connecting tubules, and cortical collecting ducts. The expression of CLC-K2 in the outer and inner medullary collecting ducts was almost absent. In contrast, a moderate signal of CLC-K2 mRNA was observed in the medullary thick ascending limb of Henle's loop, but the signal in the cortical thick ascending limb of Henle's loop was low. These results clearly demonstrated that CLC-K2 was not colocalized with CLC-K1 and that its localization along the nephron segments was relatively broad compared with that of CLC-K1.

Animals↗

PubMed1999

Cellular and subcellular immunolocalization of ClC-5 channel in mouse kidney: colocalization with H+-ATPase.

To determine the immunolocalization of ClC-5 in the mouse kidney, we developed a ClC-5-specific rat monoclonal antibody. Immunoblotting demonstrated an 85-kDa band of ClC-5 in the kidney and ClC-5 transfected cells. Immunocytochemistry revealed significant labeling of ClC-5 in brush-border membrane and subapical intracellular vesicles of the proximal tubule. In addition, apical and cytoplasmic staining was observed in the type A intercalated cells in the cortical collecting duct. In contrast, the staining was minimal in the outer and inner medullary collecting ducts and the thick ascending limb. Western blotting of vesicles immunoisolated by the ClC-5 antibody showed the presence of H+-ATPase, strongly indicating that these two proteins were present in the same membranes. Double labeling with antibodies against ClC-5 and H+-ATPase and analysis by confocal images showed that ClC-5 and H+-ATPase colocalized in these ClC-5-positive cells. These findings suggest that ClC-5 might be involved in the endocytosis and/or the H+ secretion in the proximal tubule cells and the cortical collecting duct type A intercalated cells in mouse kidney.

Amino Acid Sequence↗

PubMed1999

In vivo receptor occupancy and plasma concentration of pranidipine, a potent and long-acting dihydropyridine calcium antagonist.

The occupancy of 1,4-dihydropyridine (DHP) receptors by pranidipine was characterized in tissues of spontaneously hypertensive rats (SHR). Oral administration of pranidipine (1 and 3 mg/kg) in SHR produced significant (26-67%) decreases in the number of specific (+)-[(3)H]PN 200-110 binding sites (B(max)) with 2- to 4-fold increases in the apparent dissociation constant (K(d)) in myocardial tissues at 1, 3 and 6 h later. In these rats, there was a reduction (16-37%) of B(max) in cerebral cortical (+)-[(3)H]PN 200-110 binding. Occupancy of myocardial DHP receptors after oral administration of pranidipine correlated well with its plasma concentration. Oral administration of nifedipine (10 mg/kg) in SHR caused significant increase in K(d) values for (+)-[(3)H]PN 200-110 binding in myocardium and cerebral cortex at 1 h later. In vivo specific (+)-[(3)H]PN 200-110 binding in particulate fractions of SHR aorta was markedly (59-78%) reduced at 1, 3 and 12 h after oral administration of pranidipine (3 mg/kg), while myocardial (+)-[(3)H]PN 200-110 binding was decreased by 46-48% at 1 and 3 h later. In these rats, there was a significant decrease (34%) in cerebral cortical (+)-[(3)H]PN 200-110 binding at 3 h later. In contrast, nifedipine administration produced a similar degree of reduction (71-84%) of in vivo (+)-[(3)H]PN 200-110 binding in the myocardium, aorta and cerebral cortex. It is concluded that pranidipine may exert more selective and sustained occupation in vivo of DHP receptors in vascular tissues of SHR than in myocardial and brain tissues.

Algorithms↗

PubMed1999

Intermittent administration of human parathyroid Hormone(1-34) prevents immobilization-related bone loss by regulating bone marrow capacity for bone cells in ddY mice.

ddY mice, 6 weeks of age, were neurectomized (Nx) in the right hindlimbs and sham-operated (Sham) in the left limbs for evaluation of the effects of intermittent injections of human parathyroid hormone (hPTH) on trabecular bone turnover and bone marrow cell development in unloaded and loaded limbs. Mice were given subcutaneous injections of hPTH(1-34) five times a week at a dose of 0 (vehicle), 4 (low dose), or 40 (high dose) microg/kg of body weight for 2, 4, or 6 weeks. Histomorphometric analyses of the trabecular bone of the proximal tibiae revealed that high-dose hPTH injections preserved the trabecular bone volume of the Nx limbs, which was reduced after neurectomy, at the same level as that of the contralateral Sham limbs. The mineral apposition rate in the Nx limbs was elevated to values above even that of the Sham limbs by high-dose hPTH injections. The bone formation rate reduced by neurectomy was maintained at the Sham level by low- and high-dose hPTH injections. The neurectomy-induced increase in osteoclast number was suppressed by high-dose hPTH injections. In the bone marrow cells, the numbers of nonadherent and adherent cells per tibia obtained from the Nx and Sham limbs did not change. The hPTH injections decreased the numbers of nonadherent cells and increased those of adherent cells in both the Nx and the Sham limbs, but the effects were less marked in the Nx than in the Sham limbs even at high-dose injections. The formation of osteogenic nodules in the marrow cultures obtained from the Nx limbs was decreased after surgery and was maintained at the level of the Sham limbs by high-dose hPTH injections. The number of osteoclast-like multinucleated cells was reduced in the Sham limbs by high-dose hPTH injections. The value was increased at 2 weeks after neurectomy, but it was maintained at the Sham level by high-dose hPTH injections through the experimental period. The numbers of colony forming units-fibroblastic, which were reduced by neurectomy, and those of colony forming units for granulocytes and macrophages were not altered by hPTH injections. These results demonstrate that intermittent high-dose hPTH administration in the Nx limbs as well as in the contralateral Sham limbs has similar anabolic effects, stimulating osteoblast cell lineage and suppressing osteoclast cell lineage. The anabolic effects at 4 microg were reduced, but the effects at 40 microg seemed to be less affected by unloading due to sciatic neurectomy.

Animals↗

PubMed1999

NASDA aquatic animal experiment facilities for Space Shuttle.

National Space Development Agency of Japan (NASDA) has been developed aquatic animal experiment facilities for space experiments using NASA Space Shuttle. Vestibular Function Experiment Unit (VFEU) has been firstly designed and developed for Spacelab-J mission (STS-47), and 8 days space experiment with carp has been performed. Following, the VFEU, Aquatic Animal Experiment Unit (AAEU) has been developed to accommodate small aquatic animals second International Microgravity Laboratory mission (IML-2, STS-65). Four kinds of space experiments with goldfish, medaka, newt, and newt eggs have been performed for 15 days mission duration. Then, VFEU has been improved to accommodate marine fish under low temperature condition for Neurolab (STS-90) and STS-95 missions. 17 days (STS-90) and 9 days (STS-95) experiments with oyster toadfish have been performed by using the VFEU. This report summarizes the outline of these aquatic animal experiment facilities.

Animals↗

PubMed1999

VFEU water quality control in STS-95 mission.

In STS-95 Space Shuttle mission, an aquatic animal research facility, Vestibular Function Experiment Unit (VFEU), was flown to perform neurobiological experiment with marine fish, oyster toadfish. For this purpose, we have developed a sea water purification system using highly active nitrifying bacteria at low temperature. With this system, the water quality in the VFEU was maintained in sufficient condition to keep the toadfish in healthy state for 9 days of the mission. This report summarizes the efficiency of the filter system based on the results from pre-flight bacterial preparation, water analysis of samples taken during flight, and the post-flight analysis of the bacterial filter.

Ammonia↗

PubMed1999

Water quality management for low temperature marine fishes in space.

Vestibular Function Experiment Unit (VFEU), one of the Spacelab facility flown in Neurolab mission (STS-90) in April, 1998, was to support neurophysiological research using a marine fish, Opsanus tau (oyster toadfish). The functions of the VFEU were primarily a quality management of environmental water during the mission at 14 degrees C and for acquiring physiological signals from implanted micro-electrodes in the otolith nerves as well as the spatial acceleration of the fish. A key element of the life support system was a balanced biological filter containing two types of nitrifying bacteria, Nitrosomonas for ammonia oxidization and Nitrobacter for nitrite oxidization. Although the 16 days mission was successful, two toadfishes died in late phase of the mission. Ammonium concentration in those two life support systems elevated to remarkably high level at the end of the mission whereas the other two indicated very low. This report summarizes the results of the water quality management of the VFEU during the Neurolab mission based on analysis of water samples taken during the flight and those taken prior and just after the flight.

Animals↗