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Biomedical subjects

T Iwamura

Publications and source records attributed to T Iwamura.

At least 55 records · Page 3Linked to original sources
PubMed1992

Correlation between spontaneous metastatic potential and type I collagenolytic activity in a human pancreatic cancer cell line (SUIT-2) and sublines.

A human pancreatic cancer cell line (SUIT-2) and four sublines cloned in vitro (S2-007, S2-013, S2-020 and S2-028) were inoculated into nude mice for assessment of metastatic potentials. After 16 weeks of subcutaneous injection, the parent SUIT-2 line metastasized to the lungs and lymph nodes in three of six mice. S2-007 cells presented the highest metastatic potential in pulmonary (5/6) and lymph node (2/6) metastases among the four sublines. No metastasis was found in S2-028. The incidence of spontaneous pulmonary metastasis was correlated with that of pulmonary colonization after intravenous (i.v.) injection of cell clusters (r = 0.87, P = 0.056). Pulmonary colonization potential using single cells, however, did not always reflect a spontaneous metastatic ability. Type I collagenolytic activity in serum-free conditioned media of these cells was correlated effectively with the incidence of spontaneous pulmonary metastasis (r = 0.92, P = 0.026) and pulmonary colonization after i.v. injection of cell clusters (r = 0.95, P = 0.013). Thus, type I collagenolytic activity may possibly be essential to spontaneous cancer metastasis.

Animals↗
PubMed1989

Synthesis and analgetic activity of sulfur-containing morphinans and related compounds.

3-Acylthiomorphinans, 3-carbamoylthio-3-deoxydihydromorphine and 3-benzoylthio-9-aza-17-carbamorphinan were synthesized by Newman-Kwart rearrangement of the corresponding O-thiocarbamates. The analgetic activities were lower than that of pentazocine, and the opioid receptor binding affinities were very weak. These acylthiomorphinans showed low antinociceptive activity compared with corresponding sulfur-containing benzomorphans. 3-Carbamoylthio-deoxydihydromorphine had no significant analgetic activity.

Analgesics↗
PubMed1989

Facile synthesis of 8-benzoylthio-2,6-methano-3-benzazocines and 3-benzoylthiomorphinans having small-ring substituents.

Synthesis of 3-cyclopropylmethyl-, 3-cyclobutylmethyl-, and 3-methyl-8-benzoylthio-2,6-methano-3-benzazocines (1j-l) was performed by regio-selective chlorosulfonation of non-narcotic 8-deoxy derivatives (1a-c) followed by reduction and benzoylation. 3-Benzoylthiomorphinans (2h-j) were also obtained by the same method. Compounds having small-ring substituents (1k, 1l, 2i, 2j) were found to be weak but pure mu- and delta-opioid antagonists. The analgetic activity of 1k was almost equal to that of pentazocine.

Analgesics↗
PubMed1988

Exclusion chromatography with controlled-pore glass beads to isolate Chlorella chromatin and its applications.

A simple and rapid method was developed to isolate chromatin from the unicellular alga, Chlorella, by exclusion chromatography utilizing controlled-pore glass beads. This method takes advantage of the giant size of the chromatin supramolecules and does not require the preliminary isolation of cell nuclei. In order to raise the histone yield, commercially available materials were silanized with dimethyldichlorosilane. The isolated algal chromatin had properties similar to those of other organisms, and the histones contained all five components found in calf thymus. A hierarchy of the higher order structures was also observed in the algal chromatin. This method can be used for the study of chromatin in various cell types, especially in microbial cells, from the viewpoints of not only mere preparation but also cell dynamics and fractionation in relation to the specific components or activities. Some application examples are presented.

Cell Cycle↗
PubMed1988

A heterotrophic synchronous culture of Chlorella.

Based on the observation that photoautotrophically grown Chlorella cells fail to complete cell division under anaerobic condition in the dark, we devised a heterotrophic synchronous culture (HSC) system for this green alga. The system consists, at a temperature of 21 degrees C, of a 32 +/- 1 h period under 3% CO2 in air and the successive 12 +/- 1 h period under 0.5% O2 +/- 99.5% N2 (the sum of the two periods is equal to 44 +/- 1 h), using a semi-balanced medium containing glucose in an inorganic salt solution. This procedure could be successively repeated several times and the division index was practically 100%, as it is for Chlorella in the photoautotrophic synchronous culture (PSC). We believe this is the first successful HSC achieved by the method of alternating atmospheric oxygen tension. Synthetic patterns for DNA, RNA and protein as well as chlorophyll during the cell cycle of Chlorella in HSC were similar to those observed in PSC, and the respiratory activity of actively growing cells in HSC was twice that of those in PSC. It is hoped that this system, under the regimen of high and low oxygen tension, can be utilized for other eukaryotic cells.

Cell Count↗
PubMed1988

[Establishment and characterization of human colonic and gastric cancer cell lines].

Two human cancer cell lines, DAIT-6 from a colonic cancer and IT-25 from a gastric cancer, derived from xenografts in nude mice have been established in tissue culture and maintained for over two years. In tissue culture, DAIT-6 cells grew in a monolayered sheet with a population doubling time of about 45.0 hr, and floated or piled up to form small buds above the monolayered surface in relatively confluent cultures. Chromosomal counts ranged from 40 to 108 with a modal number of 59. The cells secreted CEA (1.7 ng/1 x 10(6) cells/24 hr) and CA19-9 (540.5 u/1 x 10(6) cells/24 hr) in spent medium. The IT-25 cells grew in a monolayered sheet with a population doubling time of about 57.8 hr in tissue culture. The IT-25 cells also secreted CEA (0.5 ng/1 x 10(6) cells/24 hr) and CA19-9 (120.0 u/1 x 10(6) cells/24 hr) in spent medium. The xenografts for DAIT-6 and IT-25 in nude mice were histopathologically classified as a moderately differentiated tubular adenocarcinoma and a well differentiated tubular adenocarcinoma, respectively.

Adenocarcinoma↗
PubMed1987

Kinetics of carcinoembryonic antigen and carbohydrate antigen 19-9 production in a human pancreatic cancer cell line (SUIT-2).

Kinetics of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) production in a human pancreatic cancer cell line (SUIT-2) were investigated. Production of CEA reached a maximum, 31.0 ng/1 X 10(6) cells, in the late stationary phase with transient decline during the early exponential phase and 15.5% of the produced CEA was released into the medium, while production of CA19-9 reached a maximum, 421 U/1 X 10(6) cells, in the early stationary phase and 68.8% of the produced CA19-9 was released into the medium. Accordingly, the kinetics of CEA and CA19-9 production of SUIT-2 in vitro might be independent. CEA was stained immunohistochemically in the cytoplasm of the cells forming small buds above the monolayer cell sheet. On the contrary, CA19-9 positive cells were observed scattered in the monolayer cell sheet and CA19-9 was stained in the cytoplasm, predominantly at the projections of the cell surface. CEA and CA19-9 were also detected in the sera of nude mice bearing SUIT-2 tumors and their concentrations correlated well with tumor volume. Correlation coefficients between tumor markers and tumor volume were 0.79 (p less than 0.01) for CEA and 0.90 (p less than 0.01) for CA19-9.

Animals↗
PubMed1987

Establishment and characterization of a human pancreatic cancer cell line (SUIT-2) producing carcinoembryonic antigen and carbohydrate antigen 19-9.

A new tumor cell line (SUIT-2) derived from a metastatic liver tumor of human pancreatic carcinoma has been established in tissue culture and in nude mice, and maintained for over five years. In tissue culture, the cells grew in a monolayered sheet with a population doubling time of about 38.2 hr, and floated or piled up to form small buds above the monolayered surface in relatively confluent cultures. Chromosome counts ranged from 34 to 176 with a modal number of 45. Subcutaneous injection of cultured cells into nude mice resulted in tumor formation, histopathologically closely resembling the original neoplasm which had been classified as moderately differentiated tubular adenocarcinoma. Electron microscopic observation of the neoplastic cells revealed a characteristic pancreatic ductal epithelium. SUIT-2 cell line produces and releases at least two tumor markers, carcinoembryonic antigen and carbohydrate antigen 19-9, propagates even in serum-free medium, and metastasizes to the regional lymph nodes in nude mice xenografts.

Aged↗
PubMed1985

High-flow-rate hydroxylapatites.

We have established a novel and simple method for preparing rigidly crystallized or granulated hydroxylapatites, which showed flow rates one order of magnitude higher in column chromatography than those of the Tiselius specimen (1). The essential difference in the procedures from the Tiselius method is that calcium phosphate, the precursor of hydroxylapatite, is generated not at room temperature but at either 45 or 95 degrees C. The capacities of the two hydroxylapatites for binding and fractionating protein, RNA, and DNA upon column chromatography were similar to those of Tiselius's hydroxylapatite. The 95 degrees C specimen can be dried with no change in the properties. Because of the reproducibly observed properties, including the extremely high flow rate with ease in handling as well as low cost and simple procedures with no additives and with no special equipment in preparation, our hydroxylapatites seem to be best so far for routine laboratory use.

Calcium Phosphates↗
PubMed1985

A compilation of analytical data from inhibition studies on DNA polymerases and some of its implications.

In connection with the characterization of two DNA polymerases (DPols) of Chlorella, we have extensively surveyed the literature on inhibition studies on DPols in various eukaryotes. By applying Tamiya's plot (1), we have obtained two parameters for each of the inhibitors, phi- and n-values, which express the enzyme sensitivity to the drug and the number of inhibitor molecules present in the enzyme-inhibitor complex that is principally involved in the inhibition, respectively. By inspecting these parameters for the three mammalian DPols, alpha-, beta-, and gamma-pols, as well as other eukaryotic DPols, we have found that: [1] inhibitors commonly utilized for characterizing various DPols can be classified into two major groups, each having two subgroups, on the basis of a comparison of the phi values among alpha-, beta-, and gamma-pols. Moreover, the grouping seems not to be merely coincidental, but to be intrinsically related to facets of the enzyme reaction, which may be taken to reflect evolutionary differences in DPol structure and function among the three DPols; [2] the remarkable n value, n = 1/2, that has been found for the inhibitors competitive with dCTP in Chlorella DPols has also been detected widely in many other eukaryotic DPols. Based on the first finding as well as many other data on various DPols, we have proposed an evolutionary scenario for eukaryotic DPols. Based on the second finding, we have hypothesized a novel role for dCTP as a cofactor, probably an apparent allosteric effector, in the nucleotide transfer reaction mechanism.

Aphidicolin↗
PubMed1984

DNA polymerases of Chlorella. II. Characterization to distinguish the two enzymes.

Previously, we reported two DNA polymerases (DPols), Pol I and Pol II, in the unicellular green alga, Chlorella (Aoshima, J., Nishimura, T., & Iwamura, T. (1982) Cell Struc. Funct. 7, 71-86). Changes in their activities during the cell cycle either in the normal and drug-inhibited courses indicated that Pol I and Pol II functioned to replicate nuclear and chloroplast DNAs, respectively. In the present work, we have examined their enzymic properties to characterize and distinguish them further. A number of inhibitors commonly used for such studies were also tested to determine their effects and the results were analyzed by use of the simple and useful "Tamiya plot." We have also analyzed the data obtained in inhibitor studies on various eukaryotic DPols in the literature using the Tamiya plot, and the results will be presented elsewhere (Iwamura, T. & Aoshima, J. (1984) J. Biochem. in press). Comparisons of the algal DPols with mammalian enzymes as regards enzymic properties and inhibition modes have led us to conclude that: [1] the algal two DPols are significantly different from each other, despite having many similarities to each other: [2] they are related in properties to any of the three mammalian DPols-alpha, -beta, and -gamma; Pol I (n-DPol) was a little more like alpha than Pol II (ch-DPol), which in turn more akin to gamma. This feature was quantitized by using vectors in a three-dimensional alpha-beta-gamma-space. Another peculiar feature derived from the Tamiya plot of the inhibitions by araCTP and aphidicolin (both being competitive with cCTP) has led us to propose a specific allosteric role of cCTP in the reaction mechanism besides its role as one of the substrates.

Cations, Divalent↗
PubMedDate not supplied

Lipoma of the falciform ligament: US, CT, and MRI appearances.

A case of lipoma of the falciform ligament was demonstrated using computed tomography (CT), ultrasonography (US), and magnetic resonance imaging (MRI). US demonstrated a heterogeneous solid mass anteriorly in the upper portion of the abdomen. CT and MRI revealed a solitary, fatty mass with a small amount of soft tissue in it.

Abdominal Neoplasms↗
PubMedDate not supplied

Correlation between CA19-9 production in vitro and histological grades of differentiation in vivo in clones isolated from a human pancreatic cancer cell line (SUIT-2).

The production of carcino-embryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were investigated in 28 clones isolated from a human pancreatic cancer cell line (SUIT-2) and related to in vitro morphology of the clones and in vivo tumorigenicity. Clones of fusiform and polygonal cells could be morphologically distinguished in confluent cultures. There was no significant difference in CEA production between fusiform-cell clones (2.10 +/- 2.70 ng/L x 10(6) per 24 h) and polygonal-cell clones (6.01 +/- 7.30 ng/L x 10(6) per 24 h), but polygonal-cell clones had higher production of CA19-9 (1176.1 +/- 1628.4 U/L x 10(6) per 24 h) than fusiform (6.0 +/- 7.3 U/L x 10(6) per 24 h; P < 0.01). Production of CA19-9 in vitro correlated with the histological grade of differentiation in vivo in nude mice (r = 0.73, P < 0.001), but CEA production did not. The polygonal-cell clones developed well-differentiated carcinomas in vivo and produced significantly more CA19-9 (P < 0.001) than fusiform-cell clones, which generally developed into poorly differentiated tubular adenocarcinomas in vivo. This cell line may provide an appropriate system for further studies of the biology and therapy of pancreatic cancer.

Adenocarcinoma↗