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T Shimada

Publications and source records attributed to T Shimada.

At least 829 records · Page 46Linked to original sources
PubMed1987

Enrichment and characterization of clonogenic epithelial cells from adult rat liver and initiation of epithelial cell strains.

A highly efficient method is described for obtaining proliferative epithelial cells from adult rat livers for the reproducible establishment of liver epithelial cell strains. When cells were isolated from livers of 10- to 15-wk-old male Fischer 344 rats by a collagenase-perfusion method, collected by centrifugation at 50 X g for 5 min, and cultured in Williams' medium E containing fetal bovine serum and dexamethasone, colonies of epithelial cells different in size and morphology from hepatocytes were obtained. Sequential perfusion with collagenase and dispase yielded numerous epithelial cell colonies. When isolated cells were fractionated by differential centrifugation, the great majority of hepatocytes were sedimented at 50 X g for 1 min, whereas many non-hepatocytic cells remained in the supernatant and could be sedimented by a second centrifugation at 50 X g for 5 min. Culture of the two fractions revealed that almost all the epithelial cell colonies were derived from cells in the non-hepatocytic cell fraction. The epithelial cells were cytochemically negative for gamma-glutamyl transpeptidase activity, whereas an increase in the activity was detected in hepatocytes with duration in culture. Ultrastructural characteristics of hepatocytes were not found in the cells of newly established cell strains. These results suggest that adult rat liver epithelial cells propagable in culture were derived from a cell type other than the hepatocyte.

Animals↗
PubMed1987

Genotoxic and mutagenic activation of aflatoxin B1 by constitutive forms of cytochrome P-450 in rat liver microsomes.

Cytochrome P-450-mediated activation of aflatoxin B1 (AFB1) to genotoxic and mutagenic products which subsequently cause induction of an umu gene expression in Salmonella typhimurium TA1535/pSK1002 has been studied in a rat liver microsomal or reconstituted monooxygenase system. Liver microsomes from male Sprague-Dawley rats had a 1.5-fold higher activity to catalyze AFB1 than did those from female rats. In addition, the activation was not increased in liver microsomes from rats pretreated with phenobarbital, 3-methylcholanthrene, a polychlorinated biphenyl mixture, or dexamethasone, suggesting that the constitutive forms of cytochrome P-450 have important roles for the activation of AFB1 in rat liver microsomes. Using 15 forms of cytochrome P-450 purified from liver microsomes of untreated and phenobarbital- and 3-methylcholanthrene-treated rats, three isozymes from untreated male rats and one isozyme from untreated female rats were found to have high reactivities in metabolizing AFB1 to genotoxic products. Cytochrome P-450 forms isolated from inducer-treated rats were relatively less active. The close correlation between induction of umu gene expression and mutagenicity with Ames/S. typhimurium TA98 system by activated metabolites of AFB1 in the reconstituted monooxygenase system suggested that the constitutive forms of cytochrome P-450 had major roles for genotoxic and mutagenic activation of AFB1 in rat liver microsomes.

Aflatoxin B1↗
PubMed1987

Clonotypic comparison of IgG anti-DNA antibodies of healthy subjects and systemic lupus erythematosus patients: studies on heterogeneity and avidity.

Qualitative characteristics of IgG anti-ssDNA antibodies were studied and compared by isoelectric focusing (IEF) and enzyme-linked immunosorbent assay (ELISA) between normal human sera (NHS) and systemic lupus erythematosus (SLE) sera. In NHS, IgG anti-ssDNA spectrotypes were observed in a high alkaline pH range (7.5 to 8.5) at physiological NaCl concentrations (0.15 M). In SLE sera the spectrotypes were found to a more intensified extent in the alkaline pH range as compared to those in NHS. With regard to avidity, analyzed by salt-dependent changes of anti-ssDNA activities, NHS showed strong ssDNA-binding bands in a wide range of pH 7.0-8.5 comparable to those in SLE sera. However, these bands became extremely weak and/or faint in pH 7.5-8.5 as the NaCl concentration was raised to 0.15 M and 0.20 M. On the other hand, SLE sera still exhibited thick binding bands at higher NaCl concentrations. This salt-dependency of these antibodies was-also demonstrated by ELISA of serum samples adjusted to contain comparable antibody levels. These findings suggest that clonotypes of IgG anti-ssDNA antibodies both in NHS and in SLE sera are essentially oligoclonal and highly cationic, and that the distinctive characteristics of these antibodies in NHS may be of low avidity, in contrast to SLE sera which exhibit high avidity.

Adult↗
PubMed1987

SOS-inducing activity of chemical carcinogens and mutagens in Salmonella typhimurium TA1535/pSK1002: examination with 151 chemicals.

The umu test system is a newly developed method to evaluate genotoxic activities of a wide variety of environmental carcinogens and mutagens (Oda et al., 1985). In the present study, we further examined the abilities of 151 chemicals to induce umu gene expression in Salmonella typhimurium TA1535/pSK1002. Among the chemicals examined, 72 compounds induced umu gene expression, which could be defined on a basis of increased beta-galactosidase activity by 2-fold over the background level. The potent genotoxic compounds without metabolic activation were adriamycin, bleomycin, daunorubicin, 1,3-dinitropyrene, 1,6-dinitropyrene, 1,8-dinitropyrene, N-ethyl-N'-nitro-N-nitrosoguanidine, furylfuramide, methyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C, 1-nitropyrene and 4-nitroquino-line-1-oxide. In the presence of S9, aflatoxin B1, 2-aminoanthracene, Glu-P-1, IQ, MeIQ, MeIQx, Trp-P-1 and Trp-P-2 also induced umu gene expression markedly. Several chemicals such as 2-acetylaminofluorene, 9-aminoacridine, azobenzene, benzanthracene, benzidine, diethyl nitrosamine, 1-nitronaphthalene, paraquat, potassium dichromate and sodium nitrite were weakly genotoxic and the induction by these compounds could be detected only when the incubation time was prolonged from 2 h to 5 h. Data are also presented that some of the chemicals such as dimethyl sulfoxide, m-dioxan, 5-fluorouracil and paraquat, which have been reported to be non-mutagenic in Ames/Salmonella assay, were found to be active in inducing umu gene expression, while the known mutagenic compounds including acrylonitrile, 4,4'-dinitrobiphenyl, furfural, methylene chloride, 1-naphthylamine, sodium azide, o-tolidine and o-toluidine were non-genotoxic in the present assay system.

Biotransformation↗
PubMed1987

Low serum reverse T3 levels in patients with primary hyperparathyroidism.

Although patients with primary hyperparathyroidism (1 degree HPT) were euthyroid, we measured serum thyroid hormone levels in 16 patients with 1 degree HPT together with 17 patients with hypercalcemia due to malignant diseases (HCM). In patients with 1 degree HPT, serum levels of T3, T4 and T3U were within normal range, but serum rT3 (reverse T3) levels (205 +/- 37 pg/ml, mean +/- SD) were significantly decreased as compared with those in normal controls (276 +/- 44 pg/ml, P less than 0.01). A significant inverse correlation was observed between the serum levels of rT3 and parathyroid hormone (PTH) (r = 0.54, P less than 0.05). After parathyroidectomy, serum rT3 levels were significantly elevated (240 +/- 56 pg/ml) compared to preoperative levels (P less than 0.01). Low levels of serum rT3 seemed to be attributed to the high levels of serum PTH. On the other hand, serum levels of T3 and T4 were low and serum rT3 levels were high in patients with HCM. Low serum rT3 allows for the differentiation of patients with 1 degree HPT from those with HCM.

Adolescent↗
PubMed1987

Accelerating effect of zinc ions on the surface-mediated activation of factor XII and prekallikrein.

The effect of zinc ions on the surface-mediated activation of factor XII and prekallikrein was studied, using the contact system reconstituted with the purified proteins from bovine and human plasmas. The sulfatide-mediated activation of factor XII and prekallikrein in the presence of high-molecular-weight (HMW) kininogen was remarkably accelerated by 10(-5) M zinc ions. This accelerating effect was observed only in the presence of HMW kininogen. The kinetic analysis of the accelerating effect of zinc ions demonstrated that zinc ions reduce the Km values and increase the Vmax values on the activation of factor XII by kallikrein and on the activation of prekallikrein by factor XIIa. The value of Vmax/Km increased 26.4-fold in the former reaction and 2.8-fold in the latter reaction, indicating that zinc ions accelerate mainly the activation of factor XII by kallikrein. In the presence of 5 x 10(-4) M zinc ions, typical difference spectra due to a red shift of tryptophan and/or tyrosine residues were observed for HMW kininogen and its derivatives but not low-molecular-weight (LMW) kininogen. Since the concentration of zinc ions required to induce the difference spectra is comparable with that to enhance the activation of factor XII and prekallikrein, it appears that there is some correlation between the conformational change of HMW kininogen and the enhancement of the activation.

Animals↗
PubMed1987

The venous skin graft method for repairing skin defects of the fingers.

A venous skin graft for the treatment of skin defects in a finger is described. This procedure involves taking a flap from the forearm together with the subcutaneous vein and anastomosing both ends of this vein to the digital artery and vein, respectively. Thirteen difficult finger wounds were resurfaced with such a venous skin graft. The sizes of the flaps ranged from 1.3 X 3.0 cm to 2 X 5 cm. The lengths of the veins taken were from 6 to 12 cm. Subcutaneous fat is thin, and there is good elasticity in the grafted flap.

Adult↗
PubMed1987

A bioserogroup of marine vibrios possessing somatic antigen factors in common with Vibrio cholerae O1.

A bioserogroup of halophilic vibrios, tentatively labelled bioserogroup 1875, strongly agglutinated by O1 antiserum of Vibrio cholerae is described. Cross-agglutination and agglutinin-absorption tests showed that these vibrios had antigens identical with the Ogawa and Inaba factors of V. cholerae O1, although they possessed their own specific antigen distinctive from the A factor that is the specific major antigen of the latter species. In addition, quantitative antigen variation similar to that of the Ogawa-to-Inaba type with V. cholerae O1 was recognized in this halophilic group. They were isolated from estuarine water and are considered to inhabit coastal aquatic environments. Phenotypically, however, this group is not identifiable with any of the species already recognized in the genus Vibrio.

Agglutination Tests↗
PubMed1987

Factors affecting the microclimate pH in rat jejunum.

1. Single-barrelled pH-sensitive microelectrodes filled with liquid ion exchanger were used to study the layer of microclimate pH in the vicinity of the surface of rat jejunum in vitro. 2. During perfusion with a Na+-containing solution of pH 7.30, a layer having a pH gradient ranging from 7.30 (pH of the luminal bulk phase) to 6.05 +/- 0.03 (pH of the deepest region) was detected in eighteen different animals. The thickness of the layer was estimated to be 600-700 microns. No regional difference was seen along the height of the villus. 3. The addition of D-glucose to the perfusion solution significantly augmented the acidity of the deepest region without changing the thickness of the layer. On the other hand, the elimination of Na+ from the perfusion solution caused a significant reduction of the pH gradient. The lowest pH changed from a control value of 6.18 +/- 0.15 (n = 13 measurements from three animals) to 6.46 +/- 0.06 (n = 13). The gradient was sensitive to amiloride in the presence of Na+, K+, Ca2+ and Cl- had no significant effect on the microclimate pH. 4. Depletion of the surface mucus by treatment with dithiothreitol significantly raised the pH of the deepest region. 5. Glycylglycine and L-carnosine were found to reduce the microclimate pH gradient significantly, while glycine did not. 6. These results indicate that H+ secretion by the Na+-H+ antiport and the formation of mucus layer are important factors for maintaining the microclimate pH layer, and that H+-coupled co-transport, such as H+-dipeptide co-transport, causes a significant diminution of the microclimate pH gradient.

Amiloride↗
PubMed1987

Novel transcription map for the B19 (human) pathogenic parvovirus.

The B19 parvovirus, a small single-stranded DNA virus of 5.4 kilobases, is pathogenic in humans. B19 has remarkable specificity for erythroid progenitor cells and has been propagated in vitro only with human erythroid bone marrow. Replication of viral DNA and the viral protein products of B19 appear similar to those of other animal parvoviruses. However, B19 transcription had unusual features in comparison with that in other animal parvoviruses. At least nine overlapping poly(A)+ transcripts were identified in infected cells; all but one contained large introns. B19 differed from other parvoviruses in the initiation of all transcripts at a strong left side promoter (p6) and the absence of a functional internal promoter; the presence of short 5' leader sequences of about 60 bases and very large introns for RNAs encoded by the right side of the genome; two separate transcription termination sites, in contrast to cotermination at the far right side of the genome for other parvoviruses; the probable utilization by three transcripts of a variant polyadenylation signal (ATTAAA or AATAAC) in the middle of the genome; and the abundance of two unique transcripts from the middle of the genome which did not code for capsid proteins. The unusual transcription map of B19 suggests that regulation of the relative abundance of transcripts occurs by splicing and termination-polyadenylation events rather than by promoter strength. In combination with the published nucleotide sequence, the novel transcription map separated the pathogenic B19 virus at a molecular level from other animal parvoviruses and human adeno-associated virus.

Bone Marrow↗
PubMed1987

Site-specific demethylation and normal chromatin structure of the human dihydrofolate reductase gene promoter after transfection into CHO cells.

The effect of in vitro methylation on the function and chromatin structure of the human dihydrofolate reductase (DHFR) promoter linked to the DHFR coding sequences (minigene) was studied after DNA-mediated gene transfer into DHFR- CHO cells. Methylation of HhaI sites reduced the transforming frequency to about 10% of control, whereas methylation of HpaII sites had a less significant effect. The integrated genes were demethylated at specific sites in the promoter sequence, namely, HpaII sites around -57 base pairs from the major start site for transcription and HhaI sites around +9, +24, or both. All other HpaII or HhaI sites in the DHFR coding region or in the plasmid sequences remained consistently methylated. The DHFR minigene, after methylation with HhaI methylase, was also introduced without selection by cotransfection with pSV2neo and selection for neor clones in G418. Preferential demethylation of the same sites was observed even without selection for the DHFR+ phenotype. Analysis of the chromatin structure of the integrated minigene revealed characteristic proximal and distal hypersensitive regions of the promoter, as previously observed in human cells. Correctly initiated DHFR mRNA was detected in all of the transformants studied. These results suggest that formation of the characteristic chromatin structure is an intrinsic property of the DHFR promoter sequence and that demethylation of specific sites accompanies gene expression.

Animals↗
PubMed1987

Noradrenaline content and release in the mesenteric artery of stroke-prone spontaneously hypertensive rats (SHRSP) and a new strain of SHRSP (M-SHRSP).

Adrenergic innervation in the main trunk of the mesenteric artery was studied in stroke-prone spontaneously hypertensive rats (SHRSP) as well as in a new strain of SHRSP (M-SHRSP) and was compared with that of normotensive Wistar Kyoto rats (WKY). Noradrenaline (NA) content and high K-induced NA release in the artery of 6-week-old SHRSP and M-SHRSP were greater than those in the artery of WKY. These results suggest that a higher adrenergic innervation of the artery might be involved in the development of hypertension in SHRSP and M-SHRSP.

Animals↗
PubMed1987

Activation of the human beta-globin promoter in K562 cells by DNA sequences 5' to the fetal gamma- or embryonic zeta-globin genes.

Regulatory sequences of the human fetal gamma-globin gene were studied by constructing composite gamma/beta globin promoters and comparing their function to that of intact beta promoters in human K562 cells. The beta-globin gene with either 1,600 or 127 basepairs of beta promoter sequence was not expressed after stable introduction into K562 cells, consistent with the known inactivity of the beta-globin gene in these cells. In contrast, a gamma/beta promoter composed of a gamma fragment spanning positions -408 to -137 joined to the 127-bp beta promoter was able to drive the beta-globin gene. The gene appeared to be inducible with hemin. A zeta-globin 5' flanking fragment also activated the beta promoter. The function of a series of composite gamma/beta promoters was then assessed by their ability to drive directly the neomycin resistance gene, again in stably transformed cells. The -408 to -137 gamma fragment activated the beta promoter in an orientation-specific manner in this assay. Deletion analysis showed that regulatory sequences were present between positions -259 and -137 of the fetal gamma-globin gene flanking region.

Cell Line↗
PubMed1987

Effects of vanadate on vascular smooth muscles of WKY and SHRSP.

The effects of vanadate on the vascular smooth muscle of Wistar Kyoto rats (WKY) and stroke prone spontaneously hypertensive rats (SHRSP) were examined. It was shown that sodium vanadate caused contraction of the aortae, mesenteric and basilar arteries of both strains, and that the reactivity was higher in SHRSP in the aorta and mesenteric artery. The vanadate-induced contractions were not blocked by 6-hydroxydopamine, adrenergic blocking agents, indomethacin or ouabain, while 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene did. An increase in K+-concentration potentiated the vanadate-induced contractions of the mesenteric arteries and minimized the difference between preparations from WKY and SHRSP. In depolarized preparations incubated in K-Tyrode's solution (140 mM KCl), vanadate induced phasic contractions followed by marked relaxation in the aortae of both species, the relaxation being more prominent in SHRSP aorta, while depolarized mesenteric arteries showed sustained contractions. It was revealed that vanadate caused contractions by acting inside the cell, and membrane permeability to vanadate might be higher in the vascular smooth muscle of SHRSP. The findings also suggested that vanadium, an inorganic element, can be involved in the initiation of hypertension in SHRSP when it acts on vascular smooth muscle.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1987

Vascular pattern of the mammalian ovary with special reference to the three-dimensional architecture of the spiral artery.

Casts of blood vessels in the ovaries of the female rat, pig and monkey were made with methacrylate, dissected out under a dissecting microscope and observed in a scanning electron microscope (SEM). The ovarian arteries and their branches were characterized by the presence of a spiral configuration. The spiral course of the arteries, however, varied greatly in detail among the different species. The arteries in the pig and monkey ovaries had tightly spiraling configurations, while there was only an image suggestive of a spiral in the rat ovarian arteries. The former species showed a rich plexus of the spiral arteries in the hilus and medulla of the organ. Their branches straightened at the transitional region between the medulla and cortex but again showed spiral configurations in the cortex. Further, the arterial branches supplying the growing and mature follicles showed a much more marked extent to the spiral configurations as compared with those of the corpus luteum. In this paper morphological findings shall be discussed in correlation with their physiological implications.

Animals↗