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Biomedical subjects

A Muramatsu

Publications and source records attributed to A Muramatsu.

At least 37 records · Page 2Linked to original sources
PubMed2000

Targeted killing of carcinoembryonic antigen (CEA)-producing cholangiocarcinoma cells by polyamidoamine dendrimer-mediated transfer of an Epstein-Barr virus (EBV)-based plasmid vector carrying the CEA promoter.

The present study reports a novel nonviral method to efficiently and specifically target carcinoembryonic antigen (CEA)-producing cholangiocarcinoma (CC) cells in vitro. Epstein-Barr virus (EBV)-based and conventional plasmid vectors were constructed that possess the beta-galactosidase (beta-gal) or herpes simplex virus-1 (HSV-1) thymidine kinase (Tk) genes as well as tandem repeats of the human genomic sequence -82 to -42 bp from the transcriptional start site of the CEA gene. The plasmids were transfected by means of polyamidoamine dendrimer into CEA-positive (HuCC-T1) or -negative cell lines. Transfection of the conventional plasmid vector with the CEA promoter and beta-gal gene resulted in a very low or undetectable level of marker gene expression even in the CEA-positive cell line. Transferring the HSV-1 Tk gene by conventional plasmid did not affect the susceptibility of HuCC-T1 cells to ganciclovir. In marked contrast, strong beta-gal expression was specifically obtained in HuCC-T1 cells by transfecting the EBV-based plasmid in which the CEA promoter and a ubiquitous promoter (SRalpha) are employed to drive the EBV-encoded nuclear antigen 1 (EBNA1) and beta-gal genes, respectively (pTES.beta). Furthermore, CEA-positive but not -negative tumor cells were rendered highly susceptible to ganciclovir when transfected with the EBV-based vector that carries the CEA promoter-EBNA1 and SRalpha-HSV-1 Tk genes (pTES.Tk). These results strongly suggest that the EBV-based plasmid vector/cationic polymer system (EBV/polyplex) equipped with the CEA promoter provides an efficient nonviral method for the targeted gene therapy of CEA-producing malignancies.

Carcinoembryonic Antigen↗
PubMed1999

Parenchymal cells proliferate and differentiate in an organotypic slice culture of the neonatal liver.

We applied organotypic slice culture of neonatal mouse liver tissues to maintain the parenchymal cells in ontogenesis and to investigate their proliferation and differentiation. Cultured tissue spread gradually over 3 weeks. Small basophilic cells formed several layers in the center of the cultured tissues, and a monolayer of polygonal cells was seen at the periphery. Albumin- and alpha-fetoprotein-immunoreactions were seen in polygonal cells, as were proliferating cell nuclear antigen-immunoreactions. Connexin 32- and 26-immunoreactions were observed in small plaques on the membrane of the polygonal cells, and electron microscopy showed gap junctional complexes. Ultrastructurally, polygonal cells had a round nucleus and abundant cytoplasmic organelles, and bile canaliculi were seen on the cytoplasmic membrane. Cytokeratin 19-immunoreactions were scattered in clusters. There were ultrastructurally bile-duct-like structures with microvilli on the inner surface of the cavity and tight junctions between their constituent cells. Quantitative analysis of albumin-, alpha-fetoprotein- and cytokeratin 19- or proliferating cell nuclear antigen-immunoreactivity in parenchymal cells showed changes of their phenotypes or maintenance of their proliferation in tissue culture. Our slice-culture system enabled us to maintain and to develop parenchymal cells in the liver tissue for at least 3 weeks. The findings suggest that organotypic slice culture applied to liver tissues in ontogenesis may be a useful tool not only to maintain parenchymal cells but also to investigate their proliferation and differentiation.

Albumins↗
PubMed1998

Increased expression of the sodium/iodide symporter in papillary thyroid carcinomas.

Iodide is concentrated to a much lesser extent by papillary thyroid carcinoma as compared with the normal gland. The Na+/I- symporter (NIS) is primarily responsible for the uptake of iodide into thyroid cells. Our objective was to compare NIS mRNA and protein expression in papillary carcinomas with those in specimens with normal thyroid. Northern blot analysis revealed a 2.8-fold increase in the level of NIS mRNA in specimens with papillary carcinoma versus specimens with normal thyroid. Immunoblot analysis using anti-human NIS antibody that was produced with a glutathione S-transferase fusion protein containing NIS protein (amino acids 466-522) showed the NIS protein at 77 kD. The NIS protein level was elevated in 7 of 17 cases of papillary carcinoma but was not elevated in the normal thyroid. Immunohistochemical staining revealed abundant NIS in 8 of 12 carcinomas, whereas NIS protein was barely detected in specimens with normal thyroid. Although considerable patient-to-patient variation was observed, our results indicate that NIS mRNA is elevated, and its protein tends to be more abundant, in a subset of papillary thyroid carcinomas than in normal thyroid tissue.

Carcinoma, Papillary↗
PubMed1998

Steady-state propofol brain:plasma and brain:blood partition coefficients and the effect-site equilibration paradox.

Based on volume-flow relationships, CNS agents that are highly lipid soluble (log octanol-water partition coefficient > 2) are expected to have equilibration half-times (T1/2 kE0) that are proportional to brain solubility. Propofol, the most lipophilic anaesthetic in clinical use, has T1/2 kE0 values of 1.7 and 2.9 min in rats and humans, respectively, compared with an expected value of at least 8 min. As a first step in exploring this discrepancy between observed and predicted values, we determined the steady state brain:plasma and brain:blood partition coefficients in rats after a 4-h infusion of propofol. Brain:plasma and brain:blood partition coefficients were 8.2 (SD 1.6) and 3.0 (0.5), respectively. T1/2 kE0 predictions based on brain: blood partitioning in rats are more in agreement with the observed equilibration half-time, suggesting that drug bound to the formed elements of blood participates in the uptake and transfer of propofol to its effect site.

Analysis of Variance↗
PubMed1997

Unilateral meningoencephalitis with hemispheric slowing on EEG.

We report a 12-year-old boy with unilateral meningoencephalitis due to non-herpes simplex virus. He experienced secondarily generalized partial seizures of the left extremities with loss of consciousness. In contrast with normal neuroimaging findings, interictal electroencephalograms (EEGs) showed prolonged slowing in the right hemisphere. This laterality agreed with the right brain dysfunction verified on neuropsychological examination. Follow-up EEG is important in such a subtle case with normal neuroimaging.

Child↗
PubMed1996

Formation Mechanism of Monodispersed alpha-Fe2O3 Particles in Dilute FeCl3 Solutions

Some ambiguity is still involved in the interpretation of the growth mechanism of monodispersed hematite (alpha-Fe2O3) particles in dilute FeCl3 solutions. Namely, there are two entirely different proposals on this issue, viz. aggregation of preformed primary particles of alpha-Fe2O3 itself and reprecipitation of the ionic species through dissolution of the preformed beta-FeOOH particles. In order to resolve this problem, the formation process was followed in detail through TEM, Electron Diffraction, XRD, FT-IR, and ICP spectrometry along with quantitative analyses on seed effects. As a result, it has been concluded that the nuclei of the hematite particles are initially generated with the formation of beta-FeOOH particles and that they are grown by deposition of the solute originally present in the solution phase and indirectly furnished from the beta-FeOOH by dissolution. As the concentration of the solute is lowered by the growth of the hematite particles, they continue to grow with the solute provided mainly from the beta-FeOOH in a steady-state of the dissolution of beta-FeOOH and growth of alpha-Fe2O3. The basic formation mechanism is common to the ellipsoidal particles grown in the presence of phosphate ions and spherical particles in their absence.

Journal Article↗
PubMed1996

[A case of ACTH-producing thymic carcinoid tumor with Cushing syndrome].

ACTH-producing thymic carcinoid tumor with Cushing syndrome in a 41-year-old male was reported. Plasma ACTH and cortisol was high, and chest X-ray film and CT scan revealed a tumor mass in the anterior mediastinum. Extended thymectomy with pretracheal lymph node dissection was performed. The microscopic findings revealed that the mass was carcinoid tumor with metastasis of anterior mediastinal lymph node. ACTH and cortisol were restored to normal range 1 week after operation. Unfortunately, he admitted seven months later because of high level of ACTH and right supraclavicular lymph nodes swelling. He underwent right neck dissection. Pathological examination proved metastatic carcinoid tumors in the dissected nodes. It is important to perform supraclavicular lymph node dissection together with extended thymectomy for thymic carcinoid tumor.

Adrenocorticotropic Hormone↗
PubMed1993

Alteration of the basement membrane in human thyroid diseases: an immunohistochemical study of type IV collagen, laminin and heparan sulphate proteoglycan.

Basement membrane (BM) alteration in thyroid diseases was examined by immunohistochemistry using antibodies for the three major BM proteins: type IV collagen, laminin and heparan sulphate proteoglycan. Linear epithelial BMs surrounding follicles accompanied by vascular BMs forming loops, similar to those seen in the normal thyroid, were observed in Graves' disease and adenomatous goitre. Hashimoto's thyroiditis showed scant epithelial BMs as a result of follicle destruction. In follicular adenomas, development of epithelial BMs seemed to be related to follicle formation; well-developed epithelial BMs were frequently seen in normo- or large-follicular type, whereas trabecular or solid types revealed scant or poorly developed epithelial BMs. Lumpy accumulation of BM proteins was detected in hyalinizing trabecular adenomas. Papillary carcinomas revealed two different types of papillae; one type contained both epithelial and vascular BMs, and the other had only vascular BMs. Epithelial BMs in invasive areas of papillary carcinoma were distributed in an irregular, interrupted manner, and were completely absent in many foci. Anaplastic carcinomas showed scant or a total loss of epithelial BMs. These results suggest that alterations of BM in thyroid diseases clearly reflect their architectural variations, presumably in connection with their function and/or biological behaviour.

Basement Membrane↗
PubMed1993

Birefringent (calcium oxalate) crystals in thyroid diseases. A clinicopathological study with possible implications for differential diagnosis.

To elucidate the nature and significance of calcium oxalate crystals in the pathologic thyroid, we used polarized light microscopy to review 357 thyroid lesions. Under polarized light, calcium oxalate crystals had brilliant birefringence, and they were invariably identified within the colloid of follicles. The highest prevalence of crystals (87.9%) was in nodular goiters; they were also found in 60.0% of follicular adenomas and 33.3% of follicular carcinomas. The prevalence of crystals in papillary carcinomas was very low (5.4%). Therefore, the overall prevalence was 69.4% in benign nodules and 7.6% in malignant nodules. A heavy deposit of crystals was seen only in benign nodules except for one case of follicular carcinoma. Graves' disease, focal thyroiditis, and subacute thyroiditis showed low prevalence: 25.0, 46.9, and 40.0%, respectively. In cases of toxic nodules, the crystals were sparsely identified within nodules, but abundantly observed in surrounding inactive tissues. Immunohistochemistry for thyroid hormones confirmed that the crystals tended to appear in inactive follicles. On tissue x-ray film, the crystals appeared as microcalcifications. As a result of these findings, we suggest that examinations of crystals are likely to be useful in the differential diagnosis of thyroid diseases and in possible estimations of the functional state of lesions.

Adenoma↗
PubMed1993

Genetic improvement of Escherichia coli for enhanced biological removal of phosphate from wastewater.

The ability of Escherichia coli MV1184 to accumulate inorganic phosphate (Pi) was enhanced by manipulating the genes involved in the transport and metabolism of Pi. The high-level Pi accumulation was achieved by modifying the genetic regulation and increasing the dosage of the E. coli genes encoding polyphosphate kinase (ppk), acetate kinase (ackA), and the phosphate-inducible transport system (pstS, pstC, pstA, and pstB). Acetate kinase was employed as an ATP regeneration system for polyphosphate synthesis. Recombinant strains, which contained either pBC29 (carrying ppk) or pEP02.2 (pst operon), removed approximately two- and threefold, respectively, more Pi from minimal medium than did the control strain. The highest rates of Pii removal were obtained by strain MV1184 containing pEP03 (ppk and ackA). However, unlike the control strain, MV1184 (pEP03) released Pi to the medium after growth had stopped. Drastic changes in growth and Pi uptake were observed when pBC29 (ppk) and pEP02.2 (pst operon) were introduced simultaneously into MV1184. Even though growth of this recombinant was severely limited in minimal medium, the recombinant could remove approximately threefold more Pi than the control strain. Consequently, the phosphorus content of this recombinant reached a maximum of approximately 16% on a dry weight basis (49% as phosphate).

Biological Transport, Active↗