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Biomedical subjects

T Takada

Publications and source records attributed to T Takada.

At least 163 records · Page 9Linked to original sources
PubMed1994

Genetic variants of ribosomal DNA and mitochondrial DNA between swamp and river buffaloes.

To clarify the genetic relationship between Swamp and River buffaloes, the restriction fragment length polymorphisms (RFLPs) of nuclear genomic ribosomal DNA (rDNA) and cytoplasmic mitochondrial DNA (mtDNA) were analysed. Blood or liver samples from 73 Swamp and three River buffaloes were collected in East and South-east Asian countries. DNA samples from cattle, goats and sheep were used for comparisons. The analysis of rDNA allowed water buffaloes, cattle, goats and sheep to be characterized by four distinct repeat-types. However, swamp and river buffaloes showed the same repeat-type. Divergence of water buffalo and cattle is considered to have occurred approximately four to six million years ago. The RFLPs for mtDNA divided water buffaloes into three haplotypes, swamp-1, swamp-2 and river types. Swamp-1 accounted for 91% of all swamp buffaloes while swamp-2 was observed only in water buffaloes from Thailand (9%). All river buffaloes were of the same haplotype. No differences were observed between swamp and river buffaloes at the rDNA level. In contrast, a few distinct differences between them were found at the mtDNA level. Therefore, mtDNA polymorphisms provide an adequate means for classifying water buffaloes into either swamp or river buffaloes.

Animals↗
PubMed1994

Mutations in the transcriptional regulatory region of the precore and core/pregenome of a hepatitis B virus with defective HBeAg production.

Termination mutations in the precore open reading frame of hepatitis B virus (HBV) variants with defective hepatitis B e antigen (HBeAg) production have been demonstrated in both infected patients who have seroconverted to anti-HBe and those with fulminant hepatitis B. A donated plasma sample was found to be positive for the hepatitis B surface antigen, but negative for both HBeAg and anti-HBe. The HBV DNA titer in the plasma was estimated to be 32 pg/ml, and circulating virus-like particles were observed by electron microscopy. The entire nucleotide sequence of the virus was determined and at least 7 nucleotides were found to be unique when compared with previously reported sequences. These nucleotides created no termination codon in the precore/core, pol, preS/S and HBx open reading frames. The deduced amino acid substitutions were 28 Arg--Gln, 94 His--Tyr, 131 Val--Ile and 132 Phe--Tyr of HBx and 715 Met--Val and 789 Asp--Asn of pol. Furthermore, the precore and core/pregenome promoter contained altered 1764 A, 1766 T and 1768 A. Therefore, mutations in regions other than the precore open reading frame can cause defective HBeAg production.

Adult↗
PubMed1994

[Microwave tumor coagulation (MTC) in liver tumor: indication and percutaneous approach].

Indications for microwave tumor coagulation (MTC) and percutaneous approach in liver tumor were investigated. The study population comprised 26 patients with unresectable liver tumor (4 with hepatocellular carcinoma, 22 with metastatic liver tumor) who underwent MTC at our department after April 1990. Concomitant therapies were alcohol injection in 2 patients, hepatectomy in 12 and selective arterial chemotherapy in 20. Percutaneous MTC was performed on 2 patients with a single lesion under general anesthesia. Following tip coagulation electrode penetration under echo guidance, the lesion was thermally coagulated at 60W. To establish indications for MTC by the effect of thermal coagulation, survival periods were compared by underlying disease, number of masses coagulated, and maximum tumor size, in 23 patients who had undergone MTC at least 1 year previously. Thirteen of these 23 survived for 1 year or longer, including all 3 with hepatocellular carcinoma, 3 with breast cancer, 2 with leiomyosarcoma (gastric, small intestine), 4 of the 10 with colon cancer and 1 of the 2 with pancreatic cancer. According to evaluation of the degree of coagulation, complete coagulation was obtained in 11 of 23, all of whom had at most 6 tumor masses (of up to 3 cm in diameter) coagulated, and 9 of whom survived for 1 year or longer. Percutaneous MTC, of low invasiveness, proved useful as a tool of regional cancer therapy.

Breast Neoplasms↗
PubMed1994

[Evaluation of bactericidal activity of arbekacin in mixed culture with MRSA and Pseudomonas aeruginosa using an in vitro pharmacokinetic simulation system].

The bactericidal activities of arbekacin (ABK), vancomycin (VCM), gentamicin (GM) and netilmicin (NTL) in mixed culture with Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa were examined using an in vitro computer programmed pharmacokinetic simulation system and also the protective effect of these agents on systemic infection in neutropenic mice was examined. In a mixed culture of S. aureus No. 235 (MRSA) and P. aeruginosa E7, ABK showed a strong bactericidal activity and an inhibition of regrowth against both bacteria, and GM and NTL showed similar effects. On the other hand, VCM showed a bactericidal activity against S. aureus No. 235, but not against P. aeruginosa. In the protective study, ABK was evidently more effective than GM, NTL or VCM against a systemic mixed infection of mice with S. aureus No. 235 and P. aeruginosa E7. In brief, the ED50 values of ABK, VCM, GM and NTL were 19.5, > 100, 40.5 and 45.2 mg/kg, respectively.

Aminoglycosides↗
PubMed1994

[A case of pneumonitis due to Rikkunshi-to].

We report a case of pneumonitis due to Rikkunshi-to. A 79-year-old woman was admitted to our hospital because of interstitial pneumonia. She complained of dry cough and dyspnea on exertion. Fine crepitations were heard on physical examination. The chest X-ray film revealed diffuse reticulonodular shadows in both lung fields. Under the suspicion of drug-induced pneumonitis, all drugs were stopped and she was given prednisolone. Consequently her complaints, laboratory data and chest X-ray findings markedly improved. Microscopic examination of transbronchial lung biopsy specimens showed interstitial pneumonia. The results of lymphocyte stimulation test and lymphocyte migration inhibition test were positive for Rikkunshi-to. Based on these findings, we diagnosed this case as pneumonitis due to Rikkunshi-to. To our knowledge, there has been no previous case of pulmonary hypersensitivity due to Rikkunshi-to reported in the world.

Aged↗
PubMed1994

[Research on the correlation between DNA recombinational mutation and cancer malignancy in human colon cancers].

The mutagenicity of quercetin, a flavonoid, was examined by means of DNA fingerprint analysis using the Pc-1 and Pc-2 minisatellite probes that efficiently detect mutations due to recombination. Treatment of FM3A and BMT-11 tumor cells with 55 microM quercetin resulted in gain and loss of bands in the fingerprints in both cell lines. The frequencies of the clones having undergone mutation were 9/26 and 2/11, using Pc-1 probe, respectively, in the two lines. These results seem to provide a molecular basis for the phenotypic variations of BMT-11 tumor cells induced by quercetin, giving direct evidence of genetic instability of the tumor cells. Moreover, we examined for a possible correlation between frequencies of DNA recombinational mutations and cancer malignancy in human colon cancers. DNA of four human colon cancer tissues and corresponding peripheral blood cells were prepared, respectively, and examined by DNA fingerprint analysis using hPc-1 polymorphic minisatellite probe. These four specimens exhibited no extra-bands resulting from recombination and/or DNA slippage at present. We would explain how the prognosis of cancer patients is related to frequencies of DNA recombinational mutation.

Aged↗
PubMed1993

Cloning of the YAP19 gene encoding a putative yeast homolog of AP19, the mammalian small chain of the clathrin-assembly proteins.

Mouse brain AP19 is the smallest polypeptide chain component of AP-1, the clathrin-assembly protein complex located at the Golgi complex. We isolated a gene, termed YAP19, potentially encoding a homolog of AP19 from the genomic DNA of the yeast Saccharomyces cerevisiae. The deduced amino acid sequence, 156 amino acids long, shows 53% identity with the mouse brain AP19 protein, but 37% with Yap17p, a yeast homolog of the mammalian AP17 in AP-2, another clathrin-assembly protein complex located at the plasma membrane. The identification of YAP19 supports the proposal that yeast cells also contain the Golgi-associated clathrin-assembly protein complex.

Adaptor Protein Complex 1↗
PubMed1993

Cloning and site-directed mutagenesis of human ADP-ribosylarginine hydrolase.

Mono-ADP-ribosylation of arginine is a reversible modification of proteins with NAD:arginine ADP-ribosyltransferases and ADP-ribosylarginine hydrolases catalyzing the opposing reactions in the cycle. ADP-ribosylarginine hydrolases differ in their dithiothreitol (DTT) requirements. Rat and mouse hydrolases require DTT for maximal activity, but calf, guinea pig, and human hydrolases are DTT-independent. To define the molecular basis for these differences, brain ADP-ribosylarginine hydrolases were cloned. Deduced amino acid sequences of mouse and rat hydrolases were 94% identical with 5 conserved cysteines. The human hydrolase sequence was 83% identical to that of rat but contained only 4 cysteines with cysteine 108 in rat corresponding to serine 103 in human. To investigate the role of rat cysteine 108, human and rat wild-type hydrolases and mutants, in which serine 103 in human was replaced by cysteine (S103C) and cysteine 108 in rat was replaced by serine (C108S), were expressed in Escherichia coli. Affinity-purified anti-rat brain hydrolase antibodies reacted with recombinant wild-type rat hydrolase, but only weakly with the C108S mutant. They did not react with human wild-type or the S103C mutant. Human hydrolase and rat C108S were DTT-independent; human S103C was, however, DTT-dependent. These data clearly show that cysteine 108 in rat hydrolase plays a critical role in DTT dependence and may be important in immunoreactivity.

Amino Acid Sequence↗
PubMed1993

Cell transplantation of genetically altered cells on biodegradable polymer scaffolds in syngeneic rats.

Many severe metabolic deficiencies in children are caused by a single gene defect with a resultant single gene product deficiency. These diseases may be amenable to permanent cure using new techniques of gene transfer and cell transplantation. In many in vivo models of retroviral mediated gene therapy, a significant limiting factor is the ability to transplant a sufficient number of modified cells. To potentially circumvent this problem, we have developed a biodegradable polymer implant system capable of supporting large numbers of genetically modified cells. In this study, we inserted a reporter gene into syngeneic cultured normal fibroblasts and then transplanted these genetically modified cells into animals using synthetic biodegradable polymer fibers as temporary cell delivery scaffolds. To begin to develop a system capable of delivering desirable proteins secreted by genetically modified cells, Fischer 344 adult rat fibroblasts were transduced in tissue culture with a retrovirus containing the reporter gene Lac Z. These genetically modified cells (1.1 x 10(7) cells/graft) were then attached to the biodegradable polymer fibers and the polymer-cell graft was transplanted subdermally into syngeneic recipients (n = 9). There was persistence of the modified cells with expression of the reporter gene for at least 30 days. The estimated number of genetically modified cells per implanted graft decreased from a pretransplant value of 1.1 +/- 0.6 x 10(7) to 3.2 +/- 0.7 x 10(6) by 15 days after transplantation (P < 0.01). Thereafter, the cell number did not vary significantly to the conclusion of the study at day 30 (3.6 +/- 1.0 x 10(6) cells/graft). Evidence of ingrowth and incorporation of other stromal elements was present in the graft by 1 week post-transplantation, as judged by counterstained hematoxylin and eosin micrograph sections. Migration of modified cells to areas outside of the polymer-cell graft was not detected. Over the course of the study, there was little degradation of the polymer implant, although by day 30, evidence of early dissolution was evident. The number of polymer fibers per high power field increased slightly from 62.5 +/- 5.8 on day 1 to 77.3 +/- 26.6 on day 30 (P > 0.2). These data suggest that the use of biodegradable polymer fibers may permit the transplantation of genetically modified cells in sufficient numbers to deliver a therapeutically useful product. Polymer matrices allow for the attachment and site-specific transplantation of genetically modified cells.

Animals↗
PubMed1993

The structure of Mycoplasma pneumoniae as determined by the freeze-substitution technique.

The ultrastructure of Mycoplasma pneumoniae FH was examined by a mild fixation method, the freeze-substitution technique, for thin-section transmission electron microscopy and the following new findings were obtained. In the cytoplasm, no nuclear region could be clearly identified. The cytoplasm was filled with many ribosome-like particles, fine fibers and electron-dense particles. The electron-dense particles appeared to be similar to the particles found in the nucleoid region of Pseudomonas aeruginosa and might therefore possibly be a kind of DNA binding protein. The cell surface was completely enveloped with a thin opaque layer. The presence of this surface layer prevented any direct contact of the cell surface with that of the two M. pneumoniae cells.

Freeze Substitution↗
PubMed1993

Telomere change and loss of heterozygosity of mouse primary tumors and cell lines.

Changes in the number of telomere repeat arrays were examined in mouse tumor cells. Telomeres that function for the protection of chromosomes were detected as bands and a smear by pulsed field gel electrophoresis and gel-hybridization using (TTAGGG)4, as a probe. Of eight primary tumors induced in F1 mice between C57BL/6 and C3H/He and between C57BL/6 and MSM, three showed telomere alteration, two having extra bands and one having lost several telomere bands. The others exhibited patterns similar to those of normal tissues. However, the change was detected in all four cell lines that were established from one of the tumors. One cell line was further cloned and examined. Two of the nine clones differed in the telomere pattern. The telomere change was also observed in two other cell lines, FM3A cells and nontransformed BALB3T3 cells. These results suggest that telomeres are highly mutable in tumor cells and cultured cell lines. Three of the tumors and one cell line were analyzed for loss of heterozygosity with 51 microsatellite probes covering all 19 autosomes. Also, karyotype analysis of the cell line was performed. No allelic loss was seen and chromosomal abnormality was rare, although aneuploidy and imbalance in chromosomal number were observed. Possible involvement of the telomere changes observed here in chromosome impairment is discussed.

Animals↗
PubMed1993

A study on gamma-aminobutyric acid (GABA) and its analogues by using molecular orbital methods: on epileptogenicity of new quinolones.

Using the molecular orbital methods, we examined molecular structure, electron density distribution, electrostatic potential field and receptor structure of gamma-aminobutyric acid (GABA), and its analogues. The following findings were obtained: a comparison of the biological activity and the morphology electrostatic potentials of GABA analogues disclosed that the active site is the amino group, and the biological activity correlates closely with the electrostatic potential structure around the amino group. The active sites were compared between the receptor-binding molecules and the GABA uptake inhibitory molecules, and the results suggested that the receptor structure differed between the two groups of molecules and that the GABA A receptors had two subtypes. On these results, the epileptogenicity of new quinolones was studied using this method. These results suggested that the new quinolones blockaded the GABA receptor-binding system and that the important active site of the new quinolones for GABA receptor-binding was the the piperazyl amino group. These results suggested that the concentration of zwitterion type of the new quinolones was very important clinically.

Animals↗
PubMed1993

A case of protein C deficiency associated with cerebral infarction and obstruction of deep leg and inferior mesenteric veins.

Protein C, a vitamin K-dependent protein, is a blood coagulation inhibitor. Its deficiency causes systemic thrombosis. A 31-year-old woman developed cerebral infarction followed by late psychomotor seizures, and thrombosis in the inferior mesenteric vein and bilateral crural veins. Her parents were first cousins. Her mother died of cerebral thrombosis in her 30's. Her elder brother died of suspected purpura fulminans immediately after birth. Her protein C activity and protein C antigen level decreased markedly and were less than 5% of those of normal controls and 0.3 microgram/ml, respectively. Her father, a paternal aunt and a maternal uncle also showed a low protein C activity and protein C antigen level. This patient seems to have congenital protein C deficiency which produced thrombosis in the leg veins and the mesenteric vein, probably cerebral infarction.

Adult↗
PubMed1993

An outbreak of Salmonella typhimurium infection in bengalees, a variety of Lonchura striata.

Bengalees (a variety of Lonchura striata) in an aviary in Nagano Prefecture died of severe diarrhea in 1991. Pathological examination revealed slight enlargement of the liver and spleen. Histopathologically, necrotic granulomatous lesions were seen in the liver. Salmonella Typhimurium was isolated from the main organs and fecal samples. No evidence of Newcastle disease or chlamydiosis was detected. The disease was finally diagnosed as S. Typhimurium infection in bengalees. In spite of some countermeasures, 198 out of 268 birds died within 6 months, a mortality rate of 74%. Epizootiological survey revealed that the infection was transmitted by birds introduced from another prefecture. This is the first report of S. Typhimurium infection in bengalees.

Animals↗