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Biomedical subjects

K Tada

Publications and source records attributed to K Tada.

At least 37 records · Page 2Linked to original sources
PubMed2001

Standing stock and production rate of phytoplankton and a red tide outbreak in a heavily eutrophic embayment, Dokai Bay, Japan.

The seasonal variation of phytoplankton biomass and primary productivity in a heavily eutrophic embayment, Dokai Bay, Japan, was determined. Dokai Bay was characterized by high phytoplankton biomass and productivity during summer and low phytoplankton biomass and productivity during other seasons. The results suggested that phytoplankton growth was limited by only irradiance and water temperature under the high nutrient concentrations available for phytoplankton growth in the entire year. Moreover, in spite of sufficient nutrient for phytoplankton growth in the entire year, a red tide occurred only in the summer period in this bay. Our results suggested that a red tide occurred by the high phytoplankton growth rate in the summer season, but in other periods surface phytoplankton was flushed out of the bay before forming the red tide, because phytoplankton growth rate was low and could not form the red tide due to low irradiance and low water temperature.

Animals↗
PubMed2001

Endogenous 5-HT tonically inhibits spontaneous firing activity of dorsal hippocampus CA1 pyramidal neurons through stimulation of 5-HT(1A) receptors in quiet awake rats: in vivo electrophysiological evidence.

The present study was performed to examine an overall effect of endogenous serotonin (5-HT) on the spontaneous firing activity of the dorsal hippocampus CA1 pyramidal neurons in quiet awake rats. A selective 5-HT(1A) antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohe xanecarboxamide (WAY-100635: 0.03-0.2 mg/kg, s.c.) significantly increased the firing activity. A depletion of 5-HT with parachlorophenylalanine (PCPA: 500 mg/kg/day x 3 days) completely abolished this increasing effect of WAY-100635. The baseline spike frequency of the PCPA-treated rats (3.90 +/- 0.39 Hz) was significantly higher than that of the vehicle-treated rats (2.09 +/- 0.19 Hz). A 5-HT(2A) antagonist ritanserin (1 mg/kg, i.p.) and a 5-HT(3/4) antagonist 2-methoxy-4-amino-5-chloro benzoic acid 2-(diethylamino) ethyl ester (SDZ-205557: 3 mg/kg, s.c.) did not modify the firing activity and the increasing effect of WAY-100635. These results suggest that, in quiet awake rats, endogenous 5-HT would tonically inhibit the spontaneous firing activity of the CA1 pyramidal neurons mainly through stimulating 5-HT(1A) receptors.

Action Potentials↗
PubMed2001

Proliferative activity of intrahepatic colorectal metastases after preoperative hemihepatic portal vein embolization.

Although hemihepatic portal vein embolization (PVE) has been used preoperatively to extend indications for hepatectomy in patients with colorectal metastases, the effects of this procedure on tumor growth and outcome remain controversial. To address this issue, we assessed the proliferative activity of intrahepatic metastases after PVE and the long-term outcome of this procedure. Eighteen patients with colorectal metastases underwent preoperative PVE between 1996 and 2000 (PVE group). Twenty-nine patients who underwent major hepatic resection without PVE served as control (non-PVE group). The hepatic parenchymal fraction of the left lobe had significantly increased from 38.1 +/- 3.2% to 45.9 +/- 2.9% 3 weeks after PVE (+20.5%, P <.0001). Tumor volume and percent tumor volume had also significantly increased from 223 +/- 89 mL to 270 +/- 97 mL (+20.8%, P =.016) and from 13.7 + 4.3% to 16.2 + 4.9% (+18.5%, P =.014), respectively. There was no apparent correlation between the increase in parenchymal volume and that in tumor volume. The Ki-67 labeling index of metastatic lesions was 46.6 +/- 7.2% in the PVE group and 35.4 +/- 12.6% in the non-PVE group (P =.013). Long-term survival was similar in the PVE and non-PVE groups, however, disease-free survival was significantly poorer in the PVE group than in the non-PVE group (P =.004). We conclude that PVE increases tumor growth and probably is associated with enhanced recurrence of disease. Although PVE is effective in extending indications for surgery, patient selection for PVE should be cautious.

Adult↗
PubMed2001

Cytomegalovirus hepatitis confirmed by in situ hybridization in 3 immunocompetent infants.

We present 3 cases of immunocompetent infants with CMV infection who showed prolonged liver dysfunction. In all cases the CMV genome was detectable in hepatocytes using the in situ hybridization method. Combination therapy with ganciclovir (GCV) and hyperimmune gammaglobulin (HGG) was instituted in 2 cases and successfully suppressed the replication of CMV, with sustained improvement in liver function. In 1 of these cases, signals for CMV DNA were undetectable in the liver 12 months after termination of combination therapy. These results help to confirm the etiology of CMV for persistent hepatitis in immunocompetent infants using the in situ hybridization method and also show the efficacy of combination therapy with a virostatic agent, GCV, and an immune-modulating agent, HGG.

Antiviral Agents↗
PubMed2001

[A case presenting severe respiratory failure with high antibody titers to Chlamydia pneumoniae].

"HITAZYME C. pneumoniae" is a diagnostic reagent that has been recently developed by adopting an ELISA method for detection of anti-Chlamydia pneumoniae (C. pneumoniae) antibodies. A case presenting bilateral interstitial opacities and severe respiratory failure with high titers of "HITAZYME C. pneumoniae" was described. Sputum, blood, serological, and bronchoalveolar lavage examinations failed to reveal other etiology to explain his severe respiratory illness. Clinicians should be aware that C. pneumoniae may cause severe respiratory failure or ARDS. Further studies are needed to evaluate the role of C. pneumoniae infection in the development of severe pneumonia or ARDS.

Antibodies, Bacterial↗
PubMed2001

Human parvovirus B19 induces cell cycle arrest at G(2) phase with accumulation of mitotic cyclins.

Human parvovirus B19 infects specifically erythroid progenitor cells, which causes transient aplastic crises and hemolytic anemias. Here, we demonstrate that erythroblastoid UT7/Epo cells infected with B19 virus fall into growth arrest with 4N DNA, indicating G(2)/M arrest. These B19 virus-infected cells displayed accumulation of cyclin A, cyclin B1, and phosphorylated cdc2 and were accompanied by an up-regulation in the kinase activity of the cdc2-cyclin B1 complex, similar to that in cells treated with the mitotic inhibitor. However, degradation of nuclear lamina and phosphorylation of histone H3 and H1 were not seen in B19 virus-infected cells, indicating that the infected cells do not enter the M phase. Accumulation of cyclin B1 was persistently localized in the cytoplasm, but not in the nucleus, suggesting that B19 virus infection of erythroid cells raises suppression of nuclear import of cyclin B1, resulting in cell cycle arrest at the G(2) phase. The B19 virus-induced G(2)/M arrest may be the critical event in the damage of erythroid progenitor cells seen in patients with B19 virus infection.

CDC2 Protein Kinase↗
PubMed2001

Constrained optimization of L-lysine production based on metabolic flux using a mathematical programming method.

Constrained optimization for microbial fermentation was studied. For optimization, we used not the maximum principle but a nonlinear programming method because of the need to consider many metabolic reactions. In the case of L-lysine fermentation, the optimization problem in L-lysine production was formulated as a nonlinear programming problem. In general, the state equations based on material balances are represented as differential equations, but such equations which are dependent on time can not be applied to a nonlinear programming problem. Therefore, the state equations were made discrete in a time base, and a new single vector which is not dependent on time was substituted. From these formulae, the objective function and the constraints using nonlinear programming problem were defined as the amount of L-lysine produced, and as a metabolic reaction model and empirical equations, respectively. Computer program was developed to solve this constrained nonlinear programming problem. The applied algorithm of the computer programming was a sequential quadratic programming method (SQP method). When the constrained nonlinear programming problem is solved using the SQP method, the maximum amount of L-lysine produced and the optimal feeding rate of L-threonine could be calculated. From the calculated results, it was clear that introduction of the equality and inequality constraints was easy. L-Lysine at a concentration up to 75.3 g/l could be produced when the fermentation was carried out under optimal conditions.

Journal Article↗
PubMed2001

Performance of a partially packed charcoal pellet bioreactor for acetic acid fermentation.

The performance of a partially packed charcoal pellet bioreactor was compared to that of a fully packed bioreactor for aerobic acetic acid production. In the fully packed charcoal pellet bioreactor, it was considered that the shortening of an actual retention time of the culture broth limited the bioreactor performance under high dilution rate and high aeration conditions. By reducing the filling ratio of charcoal pellets to 44%, which increased the actual retention time of the culture broth, the maximum productivity increased from 3.9 g/l/h in the fully packed bed bioreactor to 5.7 g/l/h in the partially packed bioreactor without affecting the operational stability.

Journal Article↗
PubMed2001

Analysis of loss of heterozygosity on chromosome 10 in patients with malignant astrocytic tumors: correlation with patient age and survival.

OBJECT: The most frequent genetic abnormality in human malignant gliomas is loss of heterozygosity (LOH) on chromosome 10. Candidate genes on chromosome 10 that are associated with the prognosis of patients with anaplastic astrocytoma (AA) and glioblastoma (GBM) were evaluated. METHODS: The authors used 12 fluorescent microsatellite markers on both arms of chromosome 10 to study LOH in 108 primary astrocytic tumors. The LOH on chromosome 10 was observed in 11 (32%) of 34 AAs and 34 (56%) of 61 GBMs. No LOH was detected in 13 low-grade gliomas. Loss of heterozygosity was not detected in any AA in the seven patients younger than 35 years, but it was discovered in 41% of the patients older than 35 years. The prognostic significance of LOH at each locus was evaluated in 89 patients older than 15 years; 33 (37%) had supratentorial AAs and 56 (63%) had supratentorial GBMs. The Cox proportional hazards model, adjusted for patient age at surgery, the preoperative Karnofsky Performance Scale score, and the extent of surgical resection revealed that LOH on marker D10S209 near the FGFR2 and DMBT1 genes was significantly associated with shorter survival in patients with AA. The LOH on markers D10S215 and D10S541, which contain the PTEN/MMAC1 gene between them, was significantly associated with shorter survival in patients with GBM. CONCLUSIONS: In the present study it is found that LOH on chromosome 10 is an age-dependent event for patients with AAs and that LOH on marker D10S209 near the FGFR2 and DMBT1 loci is a significantly unfavorable prognostic factor. It is also reported that LOH on the PTEN/MMAC1 gene is a significantly unfavorable prognostic factor in patients with GBM.

Adult↗
PubMed2001

[A case of bronchioloalveolar carcinoma with multiple cystic shadows on chest CT].

A 68-year-old woman was admitted to our hospital in 1998 with shortness of breath on exertion. On the first admission, chest radiography revealed multiple nodular shadows and areas of ground-glass appearance mainly in the basal lung fields, and chest CT scans showed multiple thin-walled cystic lesions in both lung fields. Bronchioloalveolar carcinoma was diagnosed by transbronchial lung biopsy. The CA 19-9 level in the serum was abnormally high. The disease progressed, and the patient died 7 months after diagnosis. We report this case because CT scans showed multiple cystic lesions, which is very rare. The mechanism of cystic formation in this case of lung cancer may have involved disruption of the alveolar structure and enlargement of disrupted spaces or of the check valve mechanism.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2001

Human meniscus cell: characterization of the primary culture and use for tissue engineering.

Human meniscus cells from 47 surgically excised menisci were grown in primary culture. Cell proliferation and morphologic features were evaluated in three different culture media. Human meniscus cells showed three distinguishable cell types in monolayer culture: elongated fibroblastlike cells, polygonal cells, and small round chondrocytelike cells. These cells proliferated in Dulbecco's modified Eagle's medium, but by Day 7, elongated fibroblastlike cells became predominant. Cells did not proliferate in Ham's nutrient mixture-F-12. In a mixture of Ham's nutrient mixture-F-12 and Dulbecco's modified Eagle's medium, cells proliferated, maintaining their morphologic features and their ability to express messenger ribonucleic acids for aggrecan and Types I, II, and III collagen. Hyaluronan enhanced cellular proliferation without altering morphologic features or chondroitin sulfate production. Cultured human meniscus cells attached to a porous collagen sponge after cell seeding. Gene transfer was successful and an introduced gene was expressed by the cells, indicating that human meniscus cells can undergo gene manipulation. The finding that cells collected from small surgical specimens of human meniscus could be cultured, propagated, and seeded onto a collagen scaffold holds promise for the development of a cell-based, tissue engineered collagen meniscus.

Adolescent↗
PubMed2000

A novel alternatively spliced fibroblast growth factor receptor 3 isoform lacking the acid box domain is expressed during chondrogenic differentiation of ATDC5 cells.

To determine the role of fibroblast growth factor (FGF).FGF receptor (FGFR) signaling in chondrogenesis, we analyzed the gene expression of alternatively spliced FGFRs during chondrogenic differentiation of ATDC5 cells in vitro. Two isoforms of FGFR3 were expressed in these cells. One was the complete form of FGFR3 (FGFR3) already reported, and the other was a novel one that lacks the acid box domain (FGFR3DeltaAB). The gene of FGFR3DeltaAB was expressed in undifferentiated ATDC5 cells. In contrast, the transcripts of FGFR3 were not detectable in undifferentiated cells but increased during cellular condensation, which is an obligatory step for chondrogenic differentiation. FGFR1 and FGFR2 expression was higher than that of FGFR3 in undifferentiated cells. The gene expression of cell cycle inhibitor p21 was induced during cell condensation and correlated best with the expression of FGFR3 among the FGFR isoforms expressed. The differential expression of FGFR3 isoforms during chondrogenesis suggests that these isoforms may play different roles in the regulation of growth and differentiation in chondrocytes. To define the mitogenic response of FGFR3DeltaAB and FGFR3 to FGFs, their cDNAs were stably transfected into mouse BaF3 pro-B cells. FGFR3 preferentially mediates the mitogenic response to FGF1 and poor response to FGF2. In contrast, FGFR3DeltaAB mediated a higher mitogenic response to FGF2 as well as to FGF1. In addition, FGFR3DeltaAB responds to FGF1 at lower concentrations of heparin than FGFR3 does. These results suggest that the acid box plays an important role in the regulation of FGFR3 to mediate biological activities in response to FGFs.

Alternative Splicing↗
PubMed2000

Zyxin, a regulator of actin filament assembly, targets the mitotic apparatus by interacting with h-warts/LATS1 tumor suppressor.

The mitotic apparatus plays a pivotal role in dividing cells to ensure each daughter cell receives a full set of chromosomes and complement of cytoplasm during mitosis. A human homologue of the Drosophila warts tumor suppressor, h-warts/LATS1, is an evolutionarily conserved serine/threonine kinase and a dynamic component of the mitotic apparatus. We have identified an interaction of h-warts/LATS1 with zyxin, a regulator of actin filament assembly. Zyxin is a component of focal adhesion, however, during mitosis a fraction of cytoplasmic-dispersed zyxin becomes associated with h-warts/LATS1 on the mitotic apparatus. We found that zyxin is phosphorylated specifically during mitosis, most likely by Cdc2 kinase, and that the phosphorylation regulates association with h-warts/LATS1. Furthermore, microinjection of truncated h-warts/LATS1 protein, including the zyxin-binding portion, interfered with localization of zyxin to mitotic apparatus, and the duration of mitosis of these injected cells was significantly longer than that of control cells. These findings suggest that h-warts/LATS1 and zyxin play a crucial role in controlling mitosis progression by forming a regulatory complex on mitotic apparatus.

Actins↗
PubMed2000

Gains of 8q23-qter and 20q and loss of 11q22-qter in esophageal squamous cell carcinoma associated with lymph node metastasis.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is associated with poor prognosis and lymph node metastasis is one of the critical prognostic factors. Although it is important to elucidate the genetic aberrations underlying its lymph node metastasis, to the authors' knowledge little is known regarding alterations in the primary ESCC that are linked with ESCC metastasis to the lymph nodes. METHODS: To elucidate genetic aberrations involved in the lymph node metastasis of ESCC, comparative genomic hybridization analysis was applied to 36 ESCC specimens, from 12 cases with no lymph node metastasis and 24 cases with lymph node metastasis. RESULTS: Copy number gains frequently were detected at 3q (75%), 8q23-qter (50%), 11q13 (44%), 5p14-pter (25%), 20q (25%), 7q (22%), 2p (19%), 12p (17%), and 20p (17%) and losses were detected at 18q (58%), 3p (50%), 9p (44%), 5q14-23 (39%), 4q (33%), 13q (22%), and 11q22-qter (19%). DNA amplifications were detected at four loci: 11q13, 2q12, 7q21, and 20q11.2 It is interesting to note that the gains of 8q23-qter (P < 0.0005) and 20q (P < 0.02) and loss of 11q22-qter (P < 0.05) were observed in tumors metastatic to the lymph nodes. The gains of 3q and 11q13 and losses of 18q, 3p, 9p, 5q14-23, and 4q were detected in both early and advanced stage ESCCs. CONCLUSIONS: These observations suggest that gains of 8q23-qter and 20q and loss of 11q22-qter allow the prediction of lymph node metastasis, and that gains of 3q and 11q13 and losses of 18q, 3p, 9p, 5q14-23, and 4q are associated with the development of ESCC.

Carcinoma, Squamous Cell↗
PubMed2000

Radiographic analysis of lumbar spine for low-back pain in the general population.

We sought to demonstrate a correlation between low-back pain (LBP) and the plain radiographic findings of the lumbar spine in the general population based on an analysis of 838 persons, 387 of whom presented with complaints of low-back pain. The incidence of intervertebral narrowing and irregular ossification of the vertebral end-plate image increased consistently with age and was higher in the presence of LBP in any age or gender group. Multiregression analysis was performed with the imaging factors as multivariates. As a result, multiregression equations with irregular ossification of the vertebral end-plate image, intervertebral narrowing, spondylolisthesis and abnormal lumbar lordotic angle combined as variates showed the highest significance as predictors of a relationship with LBP. The discrimination analysis was performed using the linear discriminant function, resulting in a true discrimination rate of 65%. Plain radiography of the lumbar spine is thus significant as it provides information which can be evaluated as meaningful findings in the investigation of LBP. In addition, while the significance can be increased by considering multiple factors, it is important to understand the limits of the accuracy of this prediction.

Adult↗
PubMed2000

Human glycine decarboxylase gene (GLDC) and its highly conserved processed pseudogene (psiGLDC): their structure and expression, and the identification of a large deletion in a family with nonketotic hyperglycinemia.

Mutations in the glycine decarboxylase gene (GLDC) cause nonketotic hyperglycinemia (NKH), an in-born error of metabolism characterized by severe neurological disturbance. We have determined the structure of GLDC and of its pseudogene (psiGLDC) and studied their expression for a molecular analysis of NKH. The GLDC gene spans at least 135 kb and consists of 25 exons. All donor and acceptor sites adhere to the canonical GT-AG rule, except for the donor site of intron 21, where a variant form GC is used instead of GT. The transcription initiation site has been assigned to a residue 163 bp upstream from the translation initiation triplet by primer extension analysis. The psiGLDC gene has no intron and shares 97.5% homology with the coding region of functional GLDC, suggesting that psiGLDC is a processed pseudogene that arose from the GLDC transcript about 4-8 million years ago. RNA blotting analysis has revealed that GLDC is expressed in human liver, kidney, brain, and placenta. We have also examined a patient with NKH with no detectable GLDC mRNA in his lymphoblasts. Exons 1-3 of the functional GLDC gene from this patient are not amplified by polymerase chain reaction (PCR), whereas those from control subjects are. These results suggest a large homozygous deletion (at least 30 kb) in the patient. Furthermore, we have devised a semi-quantitative PCR to estimate the number of GLDC alleles by using psiGLDC as an internal control and have confirmed the homozygosity and heterozygosity of the deletion in the patient and his parents, respectively. Structural information of GLDC and psiGLDC should facilitate the molecular analysis of NKH.

Amino Acid Oxidoreductases↗