PubMed Health⌕ Search

Biomedical subjects

H Masui

Publications and source records attributed to H Masui.

At least 91 records · Page 5Linked to original sources
PubMed1985

Vasoactive intestinal polypeptide-induced chloride secretion by a colonic epithelial cell line. Direct participation of a basolaterally localized Na+,K+,Cl- cotransport system.

We have used a well-differentiated human colonic cell line, the T84 cell line, as a model system to study the pathways of cellular ion transport involved in vasoactive intestinal polypeptide (VIP)-induced chloride secretion. A modified Ussing chamber was used to study transepithelial Na+ and Cl- fluxes across confluent monolayer cultures of the T84 cells grown on permeable supports. In a manner analogous to isolated intestine, the addition of VIP caused an increase of net Cl- secretion which accounted for the increase in short circuit current (Isc). The effect of VIP on Isc was dose dependent with a threshold stimulation at 10(-10) M VIP, and a maximal effect at 10(-8) M. Bumetanide prevented or reversed the response to VIP. Inhibition by bumetanide occurred promptly when it was added to the serosal, but not to the mucosal bathing media. Ion replacement studies demonstrated that the response to VIP required the simultaneous presence of Na+, K+, and Cl- in the serosal media. Utilizing cellular ion uptake techniques, we describe an interdependence of bumetanide-sensitive 22Na+, 86Rb+, and 36Cl- uptake, which is indicative of a Na+,K+,Cl- cotransport system in this cell line. This transport pathway was localized to the basolateral membrane. Extrapolated initial velocities of uptake for each of the three ions was consistent with the electroneutral cotransport of 1 Na+:1 K+ (Rb+):2 Cl-. Our findings indicate that VIP-induced Cl- secretion intimately involves a bumetanide-sensitive Na+,K+,Cl- cotransport system which is functionally localized to the basolateral membrane.

Biological Transport, Active↗
PubMed1984

Monoclonal anti-epidermal growth factor receptor antibodies which are inhibitors of epidermal growth factor binding and antagonists of epidermal growth factor binding and antagonists of epidermal growth factor-stimulated tyrosine protein kinase activity.

Four mouse monoclonal antibodies specific for human epidermal growth factor (EGF) receptors have been prepared using EGF receptor protein from human A431 epidermoid carcinoma cells as immunogen. We have determined the effect of these antibodies on two known functions of the EGF receptor: EGF binding and tyrosine kinase. Three of these antibodies (225, 528, and 579) are inhibitors of EGF binding, whereas the fourth (455) does not compete for binding but immunoprecipitates the EGF receptor. Inhibition is of the mixed competitive and noncompetitive type. The three competing monoclonal antibodies are antagonists of EGF-stimulated tyrosine protein kinase activity assayed both in intact cells and using an exogenous peptide substrate in solubilized membranes. These immunoglobulins are partial agonists in self-phosphorylation of the EGF receptor in solubilized membranes but exhibit only antagonist activity for this reaction in intact cells. The three competing monoclonal immunoglobulins recognize receptors in variant A431 cells with the same efficiency as in parental A431 cells. Such antagonist monoclonal antibodies can be used to control the concentration of receptors which can be activated by EGF.

Animals↗
PubMed1984

Effect of cadmium-feeding on tissue concentrations of elements in germ-free silkworm (Bombyx mori) larvae and distribution of cadmium in the alimentary canal.

Silkworm (Bombyx mori) larvae were reared on an artificial diet containing cadmium (Cd) at concentrations of 5 and 80 micrograms/g wet diet from hatching to the fourth instar and then for 5 days at the fifth instar, respectively. Concentrations of Cd and other elements in the alimentary canal, Malpighian tubes, silk gland, fat body and other organs were determined simultaneously by inductively coupled argon plasma-atomic emission spectrometry. Cd was accumulated in the alimentary canal and Malpighian tubes at concentrations of 1100 and 470 micrograms/g dry wt, respectively. The distribution of Cd in the supernatants of the two highly accumulated organs were determined on an SW column by high performance liquid chromatography-atomic absorption spectrophotometry. Cd was primarily bound to inducible high molecular weight Cd-binding proteins.

Animals↗
PubMed1984

A human colonic tumor cell line that maintains vectorial electrolyte transport.

A human colonic epithelial cell line, T84, derived from a colonic carcinoma, has been examined both morphologically and functionally. The cells grew to confluence as a monolayer with the basolateral membrane attached to the surface of the culture dish and a microvillus-studded apical membrane facing the media. Tight junctions and desmosomes were demonstrated between adjacent cells. Confluent monolayer cultures conducted vectorial electrolyte transport that could be altered by a variety of secretagogues and antisecretagogues similar to isolated intestinal tissues. This cell line will serve as an excellent model system for the study of electrolyte transport processes and their regulation by peptide hormones and neurotransmitters.

Biological Transport, Active↗
PubMed1984

Growth inhibition of human tumor cells in athymic mice by anti-epidermal growth factor receptor monoclonal antibodies.

Monoclonal antibodies (MoAbs) were raised against epidermal growth factor (EGF) receptors on a human epidermoid carcinoma cell line, A431. Administration of anti-EGF receptor MoAbs inhibited tumor formation in athymic mice by A431 cells and by another epidermal carcinoma cell line, T222. When one of the same MoAbs was used in therapy against Li-7 (a human hepatoma) and HeLa cells (a cervical carcinoma), tumor growth was not affected. The number of EGF receptors on A431 cells was about 100-fold higher than on T222, Li-7, and HeLa cells, suggesting that the number of EGF receptors may not be an important determinant in suppressing tumor growth. Three anti-EGF receptor MoAbs were used in the present studies. MoAbs 528 (immunoglobulin G2a) and 225 (immunoglobulin G1) are capable of competing with EGF for receptor binding and inhibit proliferation of A431 cells in culture. The other MoAb, 455 (immunoglobulin G1), is incapable of blocking the binding of EGF to its receptors and has no effect on the proliferation of cultured A431 cells. All three MoAbs inhibited A431 tumor growth in athymic mice, indicating that the antibody isotype and the site of binding on the EGF receptor are not the determinants of antiproliferative activity in vivo. The observation that MoAb against the receptor for EGF is cytostatic rather than cytocidal in vitro against A431 cells, yet completely prevents tumor growth in vivo, suggests that some host animal responses also may be involved in the antitumor effect. MoAbs against growth factor receptors could provide useful immunotherapeutic agents.

Animals↗
PubMed1983

Correlation of drug sensitivity on human colon adenocarcinoma cells grown in soft agar and in athymic mice.

A well-differentiated colorectal tumor T 219 which grows as a xenograft in athymic mice (human-tumor-nude-mouse system) and forms colonies in culture (soft agar colony-formation assay) has been used to test the correlation between the above two methods of exposure of human tumor cells to antineoplastic agents. In in vitro studies, two protocols were used: 1 h drug exposure and continuous drug exposure. In the 1 h drug exposure experiments six drugs, doxorubicin (DX), 4'-deoxydoxorubicin (deoDX), 4'epidoxorubicin(epiDX), 4'-O-methyldoxorubicin (O-DX), N-trifluoroacetyldoxorubicin-14-valerate (AD-32) and 5-fluorouracil (FUra) were studied, while in continuous drug exposure experiments four of the above drugs (DX, deoDX, epiDX, O-DX) were studied. The survival of the tumor clonogenic cells (HC219) was determined by counting the number of colonies formed during 13-14 days of incubation and dose-response curves were obtained. In in vivo studies, the mice were treated with all of the drugs used in in vitro 1 h drug exposure experiments (DX, deoDX, epiDX, O-DX, AD-32 and FUra). To quantitate the chemotherapeutic effectiveness of the drugs, T/C% (relative tumor volume of treated group as percentage of the control group) values were calculated each time the tumors were measured. The experimental data suggest that in vitro 1 h drug exposure results are in good agreement with the in vivo results, while the continuous drug exposure results do not agree with the in vivo data. The most active drug in in vivo studies, deoDX, was found to be the most active drug in the in vitro 1 h drug exposure experiments as well. However, in continuous drug exposure experiments, O-DX, not deoDX, was found to be the most active drug. Activities of the other drugs tested also differed from their respective activities in in vivo studies. Although the relative effectiveness of various drugs can be compared by determining molar concentrations of the drugs producing 50% inhibition of colonies (ID50) the expression, PEI = LD10/ID50 X 1000, which takes into consideration toxicity of the drugs, is probably a better indicator of the in vitro drug activity. The results suggest that soft agar colony-formation assay (with established cell lines from the same tumor) may be used for the prediction of in vivo activity of potential antineoplastic agents against human tumor xenografts in nude mice.

Adenocarcinoma↗
PubMed1982

Human amniotic fluid cells grown in a hormone-supplemented medium: suitability for prenatal diagnosis.

A new supplemented medium has been developed to improve human amniotic fluid cell growth and to reduce the dependence on exogenously added serum. The medium consists of a mixture of Ham's F12 medium and Dulbecco's modified Eagle's medium supplemented with Hepes, antibiotics, and 10 growth-promoting factors at 4% fetal bovine serum. Good clonal growth is achieved consistently in 8--13 days and is associated with large numbers of metaphase cells. Primary clones may be analyzed directly, thereby reducing difficulty with interpretation of chromosomal mosaicism. This medium could also be used for cultivation of fetal solid tissues and peripheral blood cultures of lymphocytes.

Amniotic Fluid↗
PubMed1982

Growth of hybridoma cells in serum-free medium: ethanolamine is an essential component.

A serum-free medium supplemented with a few growth factors was devised to grow lymphocyte hybridomas. The medium was developed with the hybridoma line MPC11-BL, a fusion product between a mouse plasmacytoma cell line (MPC11TG70na3) and mouse (BALB/c) spleen cells. In the process of developing the medium, ethanolamine was found to be an essential growth factor for the hybridoma. Phosphoethanolamine at 10-fold higher concentration could substitute for ethanolamine. Long-term cultivation of the cells was achieved in the defined medium supplemented with insulin, transferrin, ethanolamine, and selenium. The defined medium supported the growth of various other mouse hybridoma cell lines, mostly at a rate comparable to that observed in a serum-containing medium. After one-step ammonium sulfate precipitation of the spent medium, more than 95% of the protein recovered was immunoglobulin as shown by NaDodSO4/polyacrylamide gel electrophoresis.

Animals↗
PubMed1982

Effects of various neuropeptides on the secretion of proopiomelanocortin-derived peptides by a cultured pituitary adenoma causing Nelson's syndrome.

To clarify whether various neuropeptides found in the hypothalamus act directly on a pituitary adenoma causing Nelson's syndrome, we examined the influence of these peptides on the secretion of immunoreactive ACTH, beta-endorphin, and melanotropins, the proopiomelanocortin (POMC)-derived peptides, by the cultured pituitary adenoma from a patient with Nelson's syndrome. Results showed that somatostatin-14 and somatostatin-28 suppressed the secretion of POMC-derived peptides by the adenoma and that somatostatin-28 was as potent as somatostatin-14. Other neuropeptides such as arginine vasopressin, vasoactive intestinal polypeptide, and oxytocin stimulate the secretion of POMC-derived peptides. Substance P, TRF, Met-enkephalin and Leu-enkephalin were also found to modulate the secretion of POMC-derived peptides. This suggests that the adenoma may have multiple receptors to various neuropeptides.

Adenoma↗
PubMed1981

Secretion pattern of pro-opiomelanocortin-derived peptides by a pituitary adenoma from a patient with Cushing's disease.

Fragments of the pituitary adenoma of a patient with Cushing's disease were maintained in defined culture medium. Immunoreactive (IR) ACTH, IR alpha-MSH, IR beta-lipotropin (beta-LPH), IR beta-endorphin, and IR gamma-MSHs secreted from the adenoma were studied with gel permeation chromatography and the respective RIAs. The adenoma secreted roughly equimolar quantities of IR beta-LPH plus IR beta-endorphin, IR gamma 3-MSHs, and IR ACTHs. It also secreted IR alpha-MSH as well as IR gamma 1-MSH, although in a much lower concentration than the above four peptides. The secreted gamma 3-MSH-like peptides were found to be glycosylated. The secretion pattern suggests that this particular adenoma processes the pro-opiomelanocortin molecule in pathways which encompass those of both the pars distalis and the pars intermedia.

Adenoma↗
PubMed1981

Human cells in serum-free medium.

Cell culture media in which the usual serum supplement required for growth has been replaced with specific combinations of hormones, nutrients and purified serum proteins have been developed which allow the growth of a number of human cell types. These media afford particular advantages in terms of simplicity of experimental design for some kinds of experiments. Also, the media may be designed to be selective with regard to cell type, so that fibroblastic overgrowth of primary cultures of epithelial cells can be avoided. Often the proliferative and differentiative responses of cells in vivo are better preserved in vitro in the serum-free media, resulting in new systems in which to study cell differentiation and responses of cells to environmental factors such as hormones.

Blood Proteins↗
PubMed1981

Growth characteristics of primary tissue cultures from heterotransplanted human colorectal carcinomas in serum-free medium.

Procedures are described for the preparation of reproducible primary cultures from human colorectal tumors transplanted in the athymic nude mouse and for the quantitative evaluation of growth by means of counting suspensions of nuclei from these cultures with a Coulter counter. Growth curves of primary cultures from 11 colorectal tumors in serum-free medium are shown and discussed with respect to the in vitro conditions to be met for the propagation of in vivo stem cell populations.

Animals↗
PubMed1980

Hormonal control of human colon carcinoma cell growth in serum-free medium.

A human colon carcinoma cell line, HC84S, was established in serum-supplemented medium from a colon tumor line T84 transplanted in nude mice. These cells also grew in a serum-free, synthetic medium supplement with insulin, glucagon, epidermal growth factor, transferrin, hydrocortisone, triiodothyronine, selenium, and ascorbic acid. HC84S cells grew 3 times faster in this medium than in serum-containing medium and formed gland-like structures closely resembling the original tumor morphologically. In serum-containing medium, the cells grew as a monolayer and did not form such structures. Primary cultures from transplantable human colon tumor lines maintained in nude mice and a primary tumor from a patient were established directly in this hormone-supplemented medium in collagen-treated plastic dishes without fibroblast overgrowth. The hormone-supplemented medium may be generally useful for the establishment of human colon carcinoma cell lines.

Animals↗