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Biomedical subjects

Y Yamamura

Publications and source records attributed to Y Yamamura.

At least 253 records · Page 14Linked to original sources
PubMed1990

Characterization of new human pancreatic cancer cell lines which propagate in a protein-free chemically defined medium.

Many human cancer cell lines which have been maintained in fetal bovine serum (FBS)-supplemented medium produce and secrete many substances such as transferrin, alpha 1-antitrypsin, alpha 2-macroglobulin, alkaline phosphatase, gamma-glutamyltranspeptidase, creatine kinase, carcinoembryonic antigen, alpha-fetoprotein, carbohydrate antigen 19/9, and cytokines including colony-stimulating factors and transforming growth factor, and further they may produce small amounts of unknown substances. Usually, small amounts of substances have to be concentrated as highly as possible for detection, but FBS interferes with this procedure. A protein-free culture system is an ideal method for detecting small quantities of substances which originate from cancer cells without interference by FBS. However, we were concerned that protein-free culture may interrupt the production of the substances which have been produced in FBS-supplemented medium. In this study, we investigated the productibility of 46 kinds of well-known substances in ten newly established cell lines derived from human pancreatic cancer. These cell lines were propagated in a protein-free non-FBS-supplemented medium. Of the ten cases, one cell line alone that was derived from acinal cell carcinoma propagated as a semisuspension; on the other hand, nine cell lines that were derived from ductal cell carcinoma propagated as monolayers without piling up. This method prolongs the doubling time, which is not affected by the addition of FBS. The spent media of these cell lines were collected aseptically after the removal of cell debris and concentrated by ultrafiltration using a Pericon cassette followed by lyophilization. Using 46 kinds of available antibodies, we investigated whether or not the substances which react to these antibodies could be detected in the spent media and in the cells by enzyme-linked immunosorbent assay, Western blot analysis, and immunocytochemistry. Among these cell lines, HPC-Y11 produced and secreted the most kinds of substances, and the production of those substances was lowest in HPC-Y0. In conclusion, our protein-free culture system can be available in every laboratory, since this is not only an economical method, but also an effective method for the saving of purification procedures. Moreover, this is a most suitable method for surveying unknown substances derived from cancer cell lines.

Antibodies↗
PubMed1990

The IL-2 receptor beta-chain (p70). Ligand binding ability of the cDNA-encoding membrane and secreted forms.

The high affinity IL-2R is composed of at least two distinct subunits; alpha (p55 or Tac)- and beta (p70)-chains. Recent cDNA expression studies with lymphoid cells unequivocally demonstrated that the IL-2R beta is an indispensable component for the ligand internalization and the signal transduction via the high affinity IL-2R. Furthermore, these studies confirmed that the IL-2R beta singly expressed on T lymphoid cells represents the intermediate affinity IL-2R. In the present study, however, we show 1) the IL-2R beta expressed on a mouse fibroblast line, NIH-3T3, did not bind IL-2 under the intermediate affinity conditions, 2) nevertheless, the IL-2R beta coexpressed with the IL-2R alpha not only formed the high affinity receptor but also internalized IL-2. By the use of competitive sandwich ELISA to study the IL-2 binding ability of the IL-2R beta molecule itself, we also show that the IL-2R beta present in the detergent-solubilized cell extracts and the secreted IL-2R beta (p37) produced by the truncated cDNA are actually capable of binding IL-2, but with a much reduced affinity compared with the intact IL-2R beta expressed on the lymphoid cells. These findings lead us to postulate a more complex feature of the IL-2R than ever speculated; the IL-2R beta molecule having on its own minimal IL-2 binding ability requires a putative gamma-chain specifically present on lymphoid cells to generate the functional intermediate affinity IL-2R. The gamma-chain, however, seems not to be required as far as the formation of the high affinity IL-2R by the alpha- and beta-chains and the ligand internalization through it are concerned.

Amino Acid Sequence↗
PubMed1990

Detection of Epstein-Barr virus genome in benign polyclonal proliferative T cells of a young male patient.

Epstein-Barr virus (EBV) DNA was detected in polyclonal T cells that proliferated transiently in a 21-year-old male (referred to as H.J.) who underwent an apparently benign lymphocytosis (white blood cells, 31 x 10(6)/microL; lymphocyte, 79%) with fever, tonsillar swelling, lymphadenopathy, and hepatosplenomegaly. The symptoms and signs subsided mostly within a month of hospitalization. The major population of the lymphocytes at admission was positive for CD3, CD8 (4/8 ratio, 0.16), WT31, and DR antigen. Eight percent of the leukocytes were too blastoid to be classified as atypical lymphocytes of infectious mononucleosis (IM). The blastoid lymphocytes and the duration and degree of the lymphocytosis and hypergammaglobulinemia appeared inconsistent with IM, whereas the EBV serology indicated either EBV primary infection or a secondary alteration of normal seropositive EBV immunity. The genomic analysis of T-cell receptor beta chain in the peripheral blood mononuclear cells (PBMC) at admission with a C beta probe did not show a monoclonal rearrangement. EBV genome was detected in these cells, using the BamHI W and K probe, but not in the cells after discharge. Analysis of the EBV terminal repeat junctional sequence, using Xho I fragment of the latent membrane protein (LMP) probe binding with the terminus, did not show monoclonal or oligoclonal populations. EBV-associated nuclear antigen (EBNA) was detected in 36% of the PBMC at admission, but not in the later cells. These EBNA-positive cells were found to form rosette with sheep erythrocytes. The PBMC of six acute IM patients contained neither EBV DNA nor EBNA-positive cells. The observations in this case show a unique type of EBV infection in T cells that has not been previously reported.

Adult↗
PubMed1990

Toxicity and metabolism of trimethylarsine in mice and hamsters.

Trimethylarsine (TM-As) proved to be an arsenic compound of low toxicity, with a po LD50 of 7870 mg/kg in mice. A single po dose of 10 mg/kg of TM-As caused no hemolysis, but a single po dose of 750 mg/kg induced mild, transient hemolysis in hamsters. TM-As was very rapidly eliminated into the urine, with a biological half-life of 3.7 hr. TM-As was oxidized in vivo to form trimethylarsine oxide (TMAO) and excreted as such into the urine. TM-As was never demethylated in vivo. A mechanism was demonstrated by which a part of TM-As was eliminated directly into the expired air. We drew a conclusion that TM-As is far less an toxic than arsine, most probably due to its in vivo conversion to TMAO.

Animals↗
PubMed1990

Mapping of somatostatin receptor localization in rat brain: forebrain and diencephalon.

Using quantitative in vitro receptor autoradiography, minute distributions of 125I-Tyr11-somatostatin (SS)-14 binding sites were investigated in the rat forebrain and diencephalon. In the cerebral cortex, there was a high density of receptors observed in layers V-VI and a low density in layers I-IV. The entorhinal cortex displayed the highest receptor density of the cerebral cortices. The olfactory system had a high SS receptor density. The anterior olfactory nucleus, nucleus of the lateral olfactory tract, medial habenular nucleus and the basolateral amygdaloid nucleus showed moderate densities. In the limbic system, the CA1 and subiculum regions had high receptor densities. More detailed observations revealed high receptor densities in the oriens, radiatum and lacunosum layers and a much lower density in the pyramidal cell layer. The caudate putamen and substantia nigra showed low receptor densities, while the claustrum displayed the highest density of receptors in the rat brain. These data were not consistent with those of previous studies using 125I-SS-28 and 125I-201-995, which had shown that the high receptor density area in the basolateral amygdaloid group was identified as the lateral amygdaloid nucleus, and that the pyramidal cell layer in the hippocampus showed high receptor densities.

Animals↗
PubMed1990

Antihypertensive activity of OPC-13340, a new potent and long-acting dihydropyridine calcium antagonist, in rats.

The antihypertensive action of OPC-13340, a new dihydropyridine, was studied in rats and compared with the action of nicardipine and other dihydropyridines. OPC-13340 showed more potent and longer hypotensive action than nicardipine when administered either intravenously (i.v.) or orally in normotensive and hypertensive rats. Among 6 compounds tested, (OPC-13340, nifedipine, nitrendipine, nisoldipine, nicardipine and diltiazem), OPC-13340 was the most potent and long-acting when administered orally to spontaneously hypertensive rats (SHR). Tachycardia after administration of OPC-13340 was less or diminished earlier than that of nicardipine. Oral administration of OPC-13340 (3 mg/kg) once daily for 13 days did not cause any rebound phenomena in SHR. The compound inhibited Ca- or K-induced contractions in isolated rat aorta and shortened action potential duration in guinea pig papillary muscle, suggesting Ca channel blocking action. OPC-13340 might be useful as a drug for once-daily therapy of essential hypertension.

Action Potentials↗
PubMed1990

[Effect of S-adenosylmethionine on methylation of inorganic arsenic].

We studied the role of S-adenosylmethionine (SAM) as a methyl group donor in the methylation of inorganic arsenic in mammalians. The SAM and S-adenosylhomocysteine (SAH) levels in the livers of untreated hamsters were 74.3 +/- 8.2 and 40.0 +/- 6.4 nmol/g, respectively. The SAM level was 63.9 +/- 6.5 nmol/g following oral administration of 1.5 mg/kg of arsenic trioxide, which was 14% lower than the control level (t-test, p less than 0.05). This fall of the SAM level in the liver presumably derived from the SAM having acted as a methyl group donor. Oral administration of 1.5 mg/kg of arsenic trioxide once only to hamsters pretreated intraperitoneally with 2.0 mg/kg of SAM once only gave the following arsenic levels in the liver and urine. The dimethylated arsenic (DMA) levels in the livers of hamsters treated with SAM plus arsenic trioxide were significantly high, that is, 2 times as high as the control value at 6 hours, and 1.5 times as high as the control value at 24 hours after the administration of arsenic trioxide. The urinary DMA excretion rate was significantly higher, that is, higher by 36%, than the control value. The urinary DMA excretion rate following pretreatment with SAM was not dose-dependent. Pretreatment with methionine failed to exert any significant acceleratory effect on the methylation of arsenic trioxide. The decreasing pattern of the SAM level in the liver following administration of arsenic trioxide and the DMA behavior in the liver and urine following administration of SAM and arsenic trioxide revealed that SAM accelerated the methylation of inorganic arsenic. In other words, it appeared that SAM could be a very potent methyl group donor to inorganic arsenic.

Animals↗
PubMed1990

Excretion of tetramethyllead, trimethyllead, dimethyllead and inorganic lead after injection of tetramethyllead to rabbits.

Rabbits were divided to groups of 3, and injected either 9.9 mg of tetramethyllead (Me4Pb)/kg of body weight (7.7 mg Pb/kg) or 39.7 mg/kg (30.8 mg Pb/kg) into the ear vein once only, respectively, and urinary and fecal excretions of lead were studied for chemical species and total lead during the following 7 days. In the group injected 9.9 mg/kg, the urinary total lead excretion was composed of about 73% dimethyllead (Me2Pb2+), about 19% trimethyllead (Me3Pb+), about 6% inorganic lead (Pb2+), and about 2% Me4Pb on the day following the injection, and 100% Me3Pb+ 7 days after the injection. In the group injected 39.7 mg/kg, the urinary total lead excretion was composed of about 67% Me2Pb2+, about 14% Me3Pb+, about 17% Pb2+, and about 2% Me4Pb on the day following the injection, and about 8% Me2Pb2+, about 74% Me3Pb+, about 17% Pb2+, and about 1% Me4Pb 7 days after the injection. In both groups, the fecal total lead excretion during 7 days after the injection was entirely composed of Pb2+. During the 7 days, 1-3% of either administered dose was excreted in the urine, and 7-19% in the feces. The urinary total lead excretion in the rabbits injected Me4Pb was similar to that in the rabbits injected tetraethyllead, but the fecal total lead excretion in the former was extremely smaller. This extremely small fecal excretion of total lead appeared to have resulted from the less elimination of lead into the bile of Me4Pb-injected rabbits.

Animals↗
PubMed1990

[Tumor-degenerating factor (TDF)].

A new human fibroblast-producing factor which degenerates human tumor cells in vitro was found and designated as tumor-degenerating factor (TDF). The characteristics of the TDF were as follows: 1) The molecular weight of the TDF was estimated to be 30k by SDS-PAGE. 2) It may be basic and glycosylated. 3) Its activity was inhibited by fibronectin and, vice versa, by binding TDF molecule with fibronectin molecule. 4) Its activity was enhanced by interferons. It is possible that the TDF is an important substance concerning the interaction between tumor cells and interstitial cells.

Animals↗
PubMed1990

Alteration of muscarinic receptor subtypes in CA1 field of hippocampus in senile dementia of Alzheimer type: an autoradiographic study.

This investigation confirmed decreases in muscarinic acetylcholine receptor (mAChR) concentration in the hippocampus of patients with senile dementia of Alzheimer-type (SDAT) using a binding assay with homogenate. We performed quantitative in vitro autoradiography of mAChR in the hippocampus obtained at autopsy from non-demented controls and SDAT patients, who had a marked memory disturbance since the early stage. 3H-QNB (1.09nM) and 3H-pirenzepine (18.0nM) were used as ligands to label total mAChR and M1 receptors, respectively. Total mAChR and M1 receptor densities showed a decrease by about 20% and 25%, respectively, in the CA1 area of SDAT cases, when compared with that of normal control cases. No changes were observed in the dentate gyrus, CA3, subiculum or entorhinal cortex. These observations are thought to be partly causative of the marked memory deficits which appeared in these cases.

Adult↗
PubMed1990

[Observation of occlusal force in prosthetic crown cementings].

The method of pressure force in crown cementing was examined. Continuous occlusal force was always supported by the patients' personal occlusal force in cementing crowns. We found that continuous occlusal force continuously decreased as the occlusal force increased, and the decreasing morphologies were classified into four types, 'Rapid decrease', 'Step-wise decrease', 'Intermediate decrease' and 'Gradual decrease'.

Bite Force↗
PubMed1990

[Application of gypsum-bonded investment containing niobium carbide on casting of alloy for metal-ceramic restoration].

Experimental gypsum-bonded investments containing 0.5-5.0 wt% NbC were prepared by mechanical mixing of each powder. Setting and thermal expansion measurement, compressive strength and casting accuracy for Ni-Cr alloy for metal-ceramic restoration were investigated. Analysis of NbC during heating was carried out by X-ray diffraction, TG-DTA and SEM. NbC was oxidized to Nb2O5 with a volume change between 300-600 degrees C, as in the following equation: 2NbC + 4 1/2O2----Nb2O5 + 2CO2 The theoretical volume of 1/2Nb2O5 calculated from the lattice constants according to JCPDS file was approximately 4 times larger than that of NbC. The experimental investments of 70 wt% cristobalite and 30 wt% gypsum containing 2.0, 3.0 and 5.0 wt% NbC showed large thermal expansion of 7.0, 10.0 and 13.0% respectively. The investment containing 2.0 wt% NbC showed nearly the same casting accuracy for Ni-Cr alloys for metal-ceramic restoration as the commercial phosphate-bonded investment.

Calcium Sulfate↗
PubMed1990

[Enhancement of cell growth by human interferons].

The effects of human interferons (HuIFN) on the human osteosarcoma cells were examined. HuIFN-alpha, -beta and -gamma enhanced dose-dependently the cell growth. There was no difference in the degree of the enhancement of the cell growth among HuIFN-alpha, -beta and -gamma. The higher the cell density was, the lower the degree of the enhancement of the cell growth. When HuIFN-gamma was neutralized with anti-HuIFN-gamma, the enhancement of cell growth was not found.

Adolescent↗
PubMed1990

[A case of long surviving gastric cancer with an malignant acanthosis nigricans].

Reported the case of a 73 year old female who was diagnosed as having a gastric cancer with malignant acanthosis nigricans and had a long survival, totaling about 8 years 6 months after operation. Further, her skin lesion completely disappeared. In general, a gastric cancer with malignant acanthosis nigricans is said to have a very poor prognosis and an analysis of recent cases has indicated that the average survival is about 10 months. The reason for such a bad prognosis is thought to be that the diagnosis of a gastric cancer with malignant acanthosis nigricans is usually determined only after the cancer is far advanced.

Acanthosis Nigricans↗