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Biomedical subjects

R Sasaki

Publications and source records attributed to R Sasaki.

At least 127 records · Page 7Linked to original sources
PubMed1996

Measurement of airborne mite allergen exposure in individual subjects.

To evaluate the extent of personal exposure to airborne mite allergens, subjects were asked to carry a personal air sampler when in their houses. The level of Der 1 allergen trapped by the sampler was measured with a highly sensitive immunoassay. There were great variations in airborne Der 1 exposure in each subject. When used bedding was replaced with new allergen-free bedding, we detected a decrease in the allergen level. The use of new bedding seems to be an effective measure for reducing airborne mite allergen exposure.

Air Pollutants↗
PubMed1996

Analysis of catalytic action of transglutaminase induced in human promyelocytic leukemia (HL-60) and human hepatoblastoma (HepG2) cells.

Transglutaminase is a calcium-dependent enzyme that catalyzes an amine incorporation and a cross-linking of proteins. Intracellular transglutaminase is induced when human promyelocytic leukemia HL-60 cells are treated with retinoic acid and human hepatoblastoma HepG2 cells, with interleukin-6. To find whether the intracellular reaction catalyzed by transglutaminase increased when the enzyme is induced in these cells, the transglutaminase-catalyzed incorporation of 14C-labeled methylamine into cellular proteins was measured. The incorporation level of the labeled methylamine into proteins of HL-60 and HepG2 cells did not increase after the transglutaminase had been induced. The presence of the calcium ionophore A23187 did not affect these results. These findings suggested that even after the enzyme induction the catalytic action of intracellular transglutaminase is maintained at a constant level in these cells by unknown regulatory mechanism(s).

Calcimycin↗
PubMed1996

Sequential occurrence of hepatocellular carcinoma following Waldenström's macroglobulinemia: the pathogenetic role of chronic liver disease.

We report a case of sequential occurrence of hepatocellular carcinoma (HCC) following Waldenström's macroglobulinemia (WM) in the course of chronic liver disease. The diagnosis of WM was made in a 55-year-old man with a history of alcohol abuse. He developed HCC in the course of WM, and hepatitis C virus (HCV) infection was detected by enzyme-linked immunosorbent assay. Recent reports suggest that persistent HCV infection is related to the pathogenesis of B cell malignancy. Chronic liver disease may be associated with the pathogenesis of the double malignancies in the present case.

Carcinoma, Hepatocellular↗
PubMed1996

[Microvessel count and vascular endothelial growth factor in renal cell carcinoma].

BACKGROUND: Angiogenesis plays an important role in the growth of solid tumors. The objective of this study is to investigate the relationship between microvessel density and mRNA measurement for vascular endothelial growth factor (VEGF) as well as the kinase domain receptor (KDR) in renal cell carcinoma (RCC). METHODS: From 1992 to 1994, expression of mRNAs of VEFG, KDR and microvessel count by Factor VIII immunohistochemical staining were examined in 22 cases of RCC. RESULTS: Northern blot hybridization demonstrated that 18 tumors (82%) expressed a higher level of VEGF gene than corresponding normal renal tissues (T/N > 1) and that the expression of VEGF gene in the tumors correlated well with that of KDR gene (r = 0.780, p = 0.001). Most of the tumor cells positively reacted to immunohistochemical staining for VEGF, but all of the normal renal tissue elements did not. RT-PCR analysis revealed that mRNAs of VEGF expressed in the tumors were of soluble subclasses. The mean number of microvessels (< 50 micrometers in diameter) in the tumors was 62.7 +/- 39.1/mm2 (range 13.7-133.1) and significantly correlated with the expression of VEGF gene (r = 0.636, p = 0.001). CONCLUSIONS: The results indicate that RCC cells actively produce soluble VEGF and strongly suggest that VEGF and its receptor KDR cooperate to enhance the angiogenesis of this tumor.

Adult↗
PubMed1996

[Prognostic importance of prostate specific antigen in patients with hormonally treated stage D2 prostate carcinoma].

BACKGROUND: The objective of this study is to evaluate the relationship between PSA value and prognosis of the patients with stage D2 prostate carcinoma. METHODS: Serum prostate specific antigen was analyzed in 61 patients with stage D2 prostate carcinoma submitted to hormone therapy. RESULTS: The median values of PSA parameters were 77.6 ng/ml for the initial PSA, 91.8% for the maximal decrease, 2.7 ng/ml for the nadir, 1.1 months for the half-time time, 3.0 months for the time to nadir, 3.2 months for the doubling time after progression and 0.39 for the ratio of antemortem versus initial PSA. The median biochemical progression-free time was 15.0 months and the median actuarial survival after progression was 24.9 months. The progression-free time was significantly correlated with the normalization of PSA (p < 0.001) and the initial PSA of less than 100 ng/ml (p < 0.05), and the survival time after progression was significantly correlated with the doubling time (p < 0.05). The normalization of PSA was affected by initial value, maximal decrease rate and half-life time of PSA respectively, but not by the histological grade of the primary tumors. The doubling time was not correlated with these factors nor with the progression-free time. CONCLUSION: The results show that the initial value, nadir level and doubling time of PSA can be used as prognostic parameters for prostatic carcinoma. Both the low ratio of premortem versus initial PSA, which may reflect an increase of stem cell fraction, and the PSA doubling time after relapse, which seems similar to or shorter than that of untreated cases, will indicate an aggressive potential of hormone-refractory tumors.

Aged↗
PubMed1996

[Retrospective analysis on 21 patients with follicular lymphoma].

We retrospectively analyzed the clinical data of the 21 patients with follicular lymphoma admitted to our institution from 1977 to 1994. The frequency of follicular lymphoma was 9.1% in the 231 patients with non-Hodgkin's lymphoma. Overall survival rates at 1 year, 3 years, and 5 years were 90.2%, 78.2%, and 52.1%, respectively. The median follow-up of surviving patients and time to treatment failure (TTF) was 43 months and 30 months, respectively. The median time from disease progression to death was 171 days. In univariate analysis, factors associated with poor survival were stage IV (Ann Arbor staging system), anemia (hemoglobin level less than 10g/dl), bone marrow involvement, two or more extranodal sites, and failure in induction of complete remission (CR) in the entire course. Factors associated with short TTF were anemia, bone marrow involvement, and failure in induction of CR. In multivariate analysis, induction of CR affected survival and TTF independently.

Adult↗
PubMed1996

Sensitivity and applicability of different methods for detection of terminal transferase in leukemia.

The sensitivity of terminal deoxynucleotidyl transferase (TdT) assay methods was examined by using a mixture of the TdT-positive lymphoblastic leukemia cell line NALM-18 and the TdT-negative erythroleukemia cell line K-562. The biochemical assay could detect TdT activity in the mixture containing NALM-18 cells at concentrations of more than 10 percent. The immunofluorescent (IF) method could detect positive cells in the mixture containing NALM-18 cells at concentrations of more than 1 percent. Furthermore, an approximately 10(5)-fold increase in sensitivity was obtained by the combination of RT-PCR and subsequent Southern blotting, as compared to biochemical assay. In many leukemia cases the expression of TdT-mRNA corresponded well to that of TdT protein. However, in some patients with leukemia, only TdT-mRNA was detectable by RT-PCR without any expression of TdT protein. A PCR-based technique enables us to detect TdT transcripts at the highest sensitivity, but does not allow the characterization of each positive cell. IF analysis is simple and sensitive, but may sometimes cause nonspecific reactions. All these techniques have some advantages and some faults, therefore, the results obtained from clinical studies using these techniques should be interpreted with caution.

Base Sequence↗
PubMed1995

N-glycosylation-defective receptor for erythropoietin can transduce the ligand-induced cell proliferation signal.

Erythropoietin receptor (EPOR) contains a single N-linked sugar in an extracellular domain. It has been suggested that an erythroleukemia cell line with high sensitivity to EPO expresses a high molecular mass form of EPOR, which appears to be a highly N-glycosylated form responsible for EPO-mediated signal transduction [Sawyer and Hankins (1993) Proc. Natl. Acad. Sci. USA 90, 6849-6853]. To examine the role of the N-linked sugar chain, we prepared EPO-dependent cell lines expressing the wild-type EPOR and N-glycosylation-defective EPOR. There was little difference in the expression of EPOR on the cell surface, EPO binding kinetics, and EPO-induced cell proliferation between the clones expressing the mutant EPOR and those expressing the wild-type EPOR.

Animals↗
PubMed1995

Site-directed mutation in conserved anionic regions of guinea pig liver transglutaminase.

Transglutaminases (EC 2.3.2.13) catalyze the formation of epsilon-(gamma-glutamyl) lysine cross-links and the substitution of primary amines for the gamma-carboxamide groups of protein-bound glutamine residues. There are conserved anionic regions in transglutaminases, some of which are thought to be possible calcium-binding sites. By site-directed mutagenesis, three mutant forms of recombinant guinea-pig liver transglutaminase, in which some acidic amino acid residues in two conserved regions became nonionic, were expressed in Escherichia coli: TGM1, with Asp-231 and -232 changed to Asn; TGM2, with Glu-445, -448, -449, -450, and -452 changed to Gln; and TGM3, with the mutations of both TGM1 and TGM2. The size and level of synthesis of the mutant proteins were unchanged when monitored by immunoblotting. All mutants retained enzyme activity, and their apparent Km values for substrates during histamine incorporation into acetyl alpha s1-casein were similar to those of the wild-type enzyme, but their Vmax values were smaller. The deamidation rate of glutamine residues in the acetyl alpha s1-casein was unaffected, but the rate of protein cross-linking catalyzed by these mutants was very low. All mutations caused with the enzyme a decrease in the sensitivity to activation by calcium and an increase in the sensitivity to inhibition by GTP. These results indicated that the negative charges of some acidic amino acid residues in the two conserved anionic regions of transglutaminase are not essential for its activity but the loss of their negative charges affects some catalytic properties.

Amino Acid Sequence↗
PubMed1995

Isolation, characterization and expression of cationic peroxidase isozymes released into the medium of cultured tobacco cells.

Three glycoproteins of 34, 38 and 40 kDa were isolated from the spent medium of suspension-cultured tobacco cells. The 38-kDa and 40-kDa proteins were highly cationic peroxidases with indistinguishable enzymic properties but their structural difference was confirmed by sequence analysis of the amino-terminal regions and the recognition specificity of monoclonal antibodies. The 34-kDa protein was a moderately cationic peroxidase with enzymic properties quite different from those of the 38-kDa and 40-kDa enzymes. They were undetectable in the spent medium during the cell-proliferation phase but became abundant in the medium during the cell-expansion phase. This was confirmed quantitatively with the 40-kDa protein using the 40-kDa-specific monoclonal antibody. The mRNA expression for 40-kDa protein was at a constant basal level in the cell-proliferation phase but increased in the cell-expansion phase.

Amino Acid Sequence↗
PubMed1995

Characterization of a human glycoprotein (erythropoietin) produced in cultured tobacco cells.

Erythropoietin (Epo), a glycoprotein that regulates the formation of erythrocytes in mammals, was produced in cultured tobacco BY2 cells (Nicotiana tabacum L. cv. Bright Yellow 2) by introducing human Epo cDNA via Agrobacterium tumefaciens-mediated gene transfer. Epo was correctly processed and subsequently penetrated the plasma membrane of tobacco cells. However, it remained attached to the cell wall and was not released into the culture medium. Although Epo produced by tobacco cells was glycosylated with N-linked oligosaccharides, these carbohydrates were smaller than those of the recombinant Epo produced in mammalian cells. Epo produced in tobacco exhibited in vitro biological activities by inducing the differentiation and proliferation of erythroid cells. However, it had no in vivo biological activities. A lectin-binding assay indicated the lack of sialic acid residues in the N-linked oligosaccharides of Epo, suggesting that Epo was removed from the circulation before it reached erythropoietic tissues.

Amino Acid Sequence↗
PubMed1995

The extracts from rat submandibular glands induce the erythroid differentiation of K-562 cells.

The extracts from rat submandibular glands (SMGs) induced erythroid differentiation of K-562. The activity was non-dialysable and abolished by heat, trypsin or 2-mercaptoethanol. Follistatin, which neutralizes the erythroid differentiation factor (EDF), had no effects on this activity. Analysis by gel chromatography and polyacrylamide gel electrophoresis-isoelectric focussing showed that the characteristics of this substance were different from those of erythropoietin, TGF-beta 1, EDF, stem cell factor and insulin-like growth factor-1. These results suggest the presence of a novel substance in rat SMGs which induces erythroid differentiation of K-562.

Animals↗