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Biomedical subjects

N Nemoto

Publications and source records attributed to N Nemoto.

At least 73 records · Page 4Linked to original sources
PubMed1997

[Necrotizing sarcoid granulomatosis diagnosed by video thoracoscopic lung biopsy].

A 28-year-old woman was admitted to our hospital because of chest pain. A chest roentgenogram and a chest computed tomogram revealed many nodular shadows on both sides. Examinations of specimens obtained by and by transbronchial lung biopsy during fiberoptic bronchoscopy were not diagnostic, and therefore video thoracoscopic lung biopsy was done. The lung lesion was characterized by aggregates of epithelioid cell granulomas, along with granulomatous and necrotizing angitis. We therefore diagnosed necrotizing sarcoid granulomatosis, and began to administer prednisolone. The nodular shadows disappeared within four weeks. In this case video thoracoscopic lung biopsy was useful in the diagnosis of necrotizing sarcoid granulomatosis in the lung.

Adult↗
PubMed1996

Maintenance and activation of Cyp2e-1 gene expression in mouse hepatocytes in primary culture.

The expression of Cyp2e-1 mRNA and protein was investigated in the C57BL/6NCrj mouse hepatocytes in primary culture, as well as liver and kidney. The mRNA and protein expression in the liver was in the same range in both sexes and was not affected by orchiectomy or ovariectomy. The mRNA expression was enhanced in the kidney of ovariectomized mice, in which the protein contents were not influenced. Orchiectomy decreased the expression of both mRNA and protein. When the hepatocytes were transferred to primary culture, the amounts of the mRNA were not changed within 24 h and about half remained by day 3. However, the expression was low thereafter. The expression of the protein gradually decreased after the start of culture. Dexamethasone showed a potential as an inducer at more than 10(-8) M. Sex hormones increased the expression of this P-450 species a little in culture, but growth hormone did not. These observations indicated that glucocorticoid hormone plays a role in modifying expression of Cyp2e-1 and that the mouse hepatocyte culture is useful for examining its regulation mechanism.

Animals↗
PubMed1996

15N labeling method of peptides using a thioredoxin gene fusion expression system: an application to ACTH-(1-24).

For structure analysis of peptides by multinuclear NMR, stable isotope-labeled samples are required. A direct over-expression system by E. coli cells does not work for that purpose because of rapid degradation of the peptides and/or the mRNA in host cells. We here developed an over-expression system by means of thioredoxin gene fusion system. The fused protein composed of thioredoxin and the objective peptide was expressed in E. coli and then the peptide part was released by enterokinase. This system was successfully applied for the production of 15N-labeled human adrenocorticotropic hormone fragment (ACTH-(1-24)) as needed for multinuclear NMR analysis.

Amino Acid Sequence↗
PubMed1996

Establishment of a hepatocyte cell line producing growth-promoting factors for liver-colonizing tumor cells.

A hepatocyte-derived cell line designated MLE-15A2 was established from a primary culture of mouse hepatocytes. The MLE-15A2 cells appeared to retain the basic nature of hepatocytes in that they showed morphology of an epithelial cell type and secreted albumin into the culture medium. These cells were grown on collagen-coated plates and could be easily expanded to a large-scale culture. Therefore, MLE-15A2 cells may provide a more useful model for studying liver microenvironments than primary cultures of hepatocytes. We found that conditioned media from MLE-15A2 cells, as well as from primary cultures of hepatocytes, promoted the proliferation of highly liver-colonizing colon 26 NL-17 cells better than the poorly liver-colonizing colon 26 NL-4 cells. Moreover, the conditioned media stimulated the growth of some human colon cancer cell lines. These results indicate that MLE-15A2 cells secrete growth factors that selectively stimulate certain tumor cell types. Hepatocyte-derived growth factors may regulate selective survival and colonization of tumor cells in the process of liver metastasis. The growth-promoting activity was unaffected by dialysis, was stable at 80 degrees C for 30 minutes and was bound to a heparin-Sepharose column. The major activity was eluted from the column with 0.7-0.75 M NaCl, and some minor activities eluted with lower concentrations of NaCl. These results suggest that the active components are heterogeneous heparin-binding proteins with lower affinity to heparin than platelet-derived and fibroblast growth factors.

Animals↗
PubMed1995

A model of the virus-type strategy in the early stage of encoded molecular evolution.

Recent advances in evolutionary molecular engineering have revealed that the essential nature of a "virus" in the evolutionary aspect is its bonding strategy for assignment of the phenotype to its genotype. Based on the definition of "virus"-type and "cell"-type of the assignment strategy, we propose a virus-early/cell-late model of the history of life. The first encoded protein is assumed to be a cofactor of replication ribozyme in the RNA world and to be bound to its genetic RNA. As such a virus-type strategy could introduce the Darwinian selection process into the hypercycle with translation, a hypercycle with virus-like members could make the replicase protein and the translation system gradually evolve together out of the RNA world without a proto-cell. Moreover, they could evolve much faster by this virus-type strategy than by a primitive cellular organism.

Animals↗
PubMed1995

Glucocorticoid and sex hormones as activating or modulating factors for expression of Cyp2b-9 and Cyp2b-10 in the mouse liver and hepatocytes.

The effects of male and female hormones as well as glucocorticoid upon the expression of Cyp2b-9 and Cyp2b-10 were investigated in C57BL/6 mouse liver and hepatocytes in primary culture. Their expression in the untreated female liver was higher than that in the male liver. More Cyp2b-9 mRNA than Cyp2b-10 was present in the female than in the male liver, whereas the levels of Cyp2b-10 were higher in the male. Phenobarbital increased Cyp2b-10 expression more than that of Cyp2b-9 in both sexes. Treatment with beta-estradiol also induced both in the male liver, with more Cyp2b-10 than Cyp2b-9 being found. In the female liver beta-estradiol and testosterone slightly increased the levels of Cyp2b-10, whereas the expression of Cyp2b-9 was reduced. Ovarectomy did not reduce the expression of the two mRNAs, but rather increased them. Using the spheroid culture system, in which mouse hepatocytes were cultured as multicellular aggregates and in which both mRNAs were expressed for a number of days, beta-estradiol as well as phenobarbital potently induced mRNA in hepatocytes from either sex and the inducibility at 10(-5) M corresponded to 10(-3) M phenobarbital. The expression level of Cyp2b-10 mRNA by phenobarbital or beta-estradiol was higher than that of Cyp2b-9, as observed in vivo, and > 10(-7) M beta-estradiol induced both in vitro. Dexamethasone induced the expression of more Cyp2b-10 mRNA than Cyp2b-9, and it was necessary for the expression by either phenobarbital or beta-estradiol. The expression was not enhanced in vitro by concomitant exposure of beta-estradiol and phenobarbital. Among the other female hormones tested, estrone induced Cyp2b-9 and Cyp2b-10 mRNAs at levels equivalent to those induced by beta-estradiol, and estriol and progesterone had a lower potential for the induction. Male hormones, such as androstenedione and testosterone, also had inducing potency in vitro. However, testosterone concentration dependently reduced the expression in cells cultured without dexamethasone. Tamoxifen or cryproterone, having antiestrogenic or antiandrogenic effects, respectively, also induced Cyp2b-9 and Cyp2b-10 mRNA. The suppressive effect of growth hormone on the expression of the mRNA was slight. The observation that endogenous hormones altered the expression of Cyp2b-9 and Cyp2b-10 in vivo and in vitro suggested that male and female hormones, as well as glucocorticoid, play activating or modulating roles in the constitutive expression of P450s.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Solution structure of omega-conotoxin MVIIC determined by NMR.

The solution structure of the P- and Q-type Ca2+ channel blocker, omega-conotoxin MVIIC (a peptidic neurotoxin composed of 26 amino acid residues), has been determined by 1H-NMR and simulated annealing calculations. The resulting calculated structures converged very well to a conformation with an average value of pairwised RMSD for N, C alpha and C' of 0.62 A. Lys-25 is buried in the molecule and less flexible so that among the four Lys residues, its side chain provides the lowest reactivity on biotinylation and the mono-biotinylation in this residue less influences the biological activity.

Amino Acid Sequence↗
PubMed1995

Maintenance of phenobarbital-inducible Cyp2b gene expression in C57BL/6 mouse hepatocytes in primary culture as spheroids.

Expression of the Cyp2b-9 and Cyp2b-10 genes was investigated in primary cultured adult C57BL/6NCrj mouse hepatocytes in monolayers or during the formation of spheroids (multicellular aggregates). Both the constitutive and phenobarbital-inducible expression of Cyp2b-9 and Cyp2b-10 mRNA decreased rapidly after transferring the hepatocytes to monolayer culture. The decrease was dependent on cell-density, and became more rapid in more densely seeded cells. However, in spheroid culture, the Cyp2b-9 and Cyp2b-10 mRNAs were induced by phenobarbital at high levels for at least 4 days either with continuous exposure from the start of cultivation or for 24 h before harvesting. The expression of both Cyp2b-9 and Cyp2b-10 species was confirmed by either reverse transcriptase-polymerase chain reaction or Western blotting. Although more Cyp2b-9 than Cyp2b-10 was expressed in the liver of control mice, the amounts of the latter became relatively overwhelming in untreated hepatocytes because of a faster decline of Cyp2b-9 species in culture. The level of mRNA induced by phenobarbital was concentration-dependent, the highest being at 2 or 4 mM, which was equivalent to in vivo treatment levels. There was more Cyp2b-10 species than those of Cyp2b-9 after exposure to phenobarbital both in vivo and in vitro. Phenobarbital also induced CYP1A2 mRNA, which was again peculiar to spheroid culture. Although the expression levels of both Cyp2b-9 and Cyp2b-10 species was very low in hepatocytes cultured without dexamethasone even in the presence of phenobarbital, the addition of 10(-7) or 10(-6) M dexamethasone caused an increase in the mRNA. When given concomitantly with phenobarbital, the expression was greatly enhanced. Nicotinamide or isonicotinamide similarly enhanced the expression of the two mRNA species, but the levels in monolayer cultures were still far lower than those in vivo. In contrast to the findings for mRNA expression, the protein levels in the presence of nicotinamide were similar to those in vivo under both monolayer and spheroid conditions. Since previous efforts to maintain expression of the CYP2B1 and CYP2B2 genes in primary cultured rat hepatocytes, orthologous to mouse Cyp2b-9 and Cyp2b-10 genes, required special cell attachment factors, our spheroid culture system, in which mouse hepatocytes are simply seeded onto noncoated dishes, has advantages for mechanistic studies.

Animals↗
PubMed1995

[Quality assurance of pathology laboratories: analysis of histopathological diagnosis of endoscopical biopsies from lower alimentary tract based on specimen types].

As a part of the internal quality assurance in the pathology laboratories, we focused on the diagnosis of biopsies from the lower alimentary tract, and investigated the number of independent lesions contributing the specimens, biopsy pieces, and paraffin blocks prepared in each pathological examination, from the standpoint of the types of biopsy procedures employed. In addition, we compared those of pre- and post-operative diagnoses, and examined the adequacy in the cases with repeated biopsies. Regarding the procedures, polypectomy and EMR (endoscopical mucosal resection) accounted for more than 60% of all the specimens handled during the study period. Most of the specimens taken by polypectomy or EMR were derived from neoplastic conditions, and roughly 40% of them were from malignancies including borderline lesions in a narrow sense. The examination of the surgically resected specimens confirmed a hundred percent accuracy ratio of the diagnosis on the biopsy specimens. Three cases (7.1%) out of 42 malignancies resected needed repeated biopsies in preoperative confirmation of malignancy, while the remainder (92.9%) had been diagnosed at the initial biopsy. The result disclosed that biopsies possessing both diagnostic and therapeutic value (polypectomy and EMR) are apparently increased in the field of lower alimentary tract, and the difficulty and efforts required for diagnosis are quite different and depend on the biopsy procedures employed.

Biopsy↗
PubMed1994

Expression of recombinase-activating genes (RAG-1 and 2) in human decidual mononuclear cells.

Recombinase-activating genes (RAG-1 and RAG-2) are expressed in immature T or B lymphocytes and possess activity to induce V(D)J rearrangement in TCR and Ig genes. We examined their expression in human decidual and non-pregnant endometrial samples using a highly sensitive RT-PCR technique. Expression of RAG-1 and 2 was noted in all (13/13) pregnant decidual tissues obtained at different gestational stages. After anti-human Ig treatment to rule out the possibility of RAG-1,2 expression from decidual B-cells, strong expression of RAGs was still noted in B cell depleted decidual cells in contrast to lymph nodes and PBMC that lost RAG mRNA expression after this treatment. After FACS mediated cell sorting, strong expression of RAG-1,2 was noted in CD16-CD56bright cells and weak expression in CD3+ cells. Although CD16-CD56bright cells lack surface CD3, they express CD3 epsilon mRNA only detectable by RT-PCR. Our results suggest the nature of decidual CD16-CD56bright cells as a progenitor of extrathymic T cells that possess RAG-1 and 2 mRNA as markers of their immaturity, and possibly differentiate into CD3+ extrathymic T-cells in the decidua under the influence of trophoblastic cells. We propose the human decidua as a new site of extrathymic T-cells differentiation and propose possible roles of trophoblastic cells to attract progenitor lymphocytes of bone marrow origin and trigger their TCR rearrangement as thymic epithelial cells.

Adult↗
PubMed1994

Elevated expression of the Cyp1a2 gene in the presence of nicotinamide by adult mouse hepatocytes in primary culture.

Effects of nicotinamide on expression of Cyp1a1 and Cyp1a2 genes were investigated in adult C57BL/6NCrj mouse hepatocytes in primary culture. The cells were cultivated for up to 8 days as monolayers or spheroids (multicellular aggregates), respectively, on collagen-coated or noncoated dishes. CYP1A1 mRNA was prominently induced after exposure to 3-methylcholanthrene (MCA) throughout the observation period with either type of culture. In monolayer-cultured cells, substantial induction of CYP1A2 mRNA by MCA was observed only at day 1 of cultivation, followed by a decrease to very low levels thereafter. In contrast, prominent elevation of both mRNA species in spheroid culture was observed throughout the 8-day experimental period. In the presence of nicotinamide, the decrease in expression of CYP1A2 mRNA in monolayer-cultured hepatocytes was restored concentration-dependently and at 10 mM nicotinamide the induced amounts were equivalent to those observed in spheroid cells. Nicotinamide also elevated CYP1A2 mRNA expression in spheroid culture, but in both cases induction of CYP1A1 mRNA decreased. Constitutive expression of CYP1A2 mRNA in monolayer culture rapidly decreased with increasing culture period, but addition of nicotinamide likewise inhibited the decrease. Nicotinamide also restored considerable expression of CYP1A2 mRNA when not present from the start of cultivation, but added 24 h before. Activities of aryl hydrocarbon hydroxylase (AHH) and acetanilide-4-hydroxylase (AAH) were elevated with either type of culture after treatment with MCA and the presence of nicotinamide further increased the AAH, resulting in an increment in the activity ratio of AAH vs AHH. Intracellular contents of NAD were considerably elevated by addition of nicotinamide. However, isonicotinamide, which is not converted to NAD in the cell, also elevated CYP1A2 mRNA expression prominently. Furthermore, NAD contents in spheroid culture were not higher than those in monolayer culture. These observations indicate that the presence of nicotinamide in the medium restores constitutive and inducible expression of Cyp1a2 gene, independent of NAD, and thus the compound is useful for studying the underlying mechanism of regulation of this gene in adult mouse hepatocytes in monolayer culture.

Animals↗
PubMed1994

Arteriovenous malformation occluded by Masson's vegetant intravascular haemangioendothelioma and complicated with intracerebral haematoma.

A case of arteriovenous malformation occluded by Masson's vegetant intravascular haemangioendothelioma and complicated with intracerebral haemorrhage in an 18-year-old woman is reported. Marked endothelial proliferation was found in the vascular lumen of draining vein. The haemorrhage appeared to have resulted from impaired venous drainage from the arteriovenous malformation.

Adolescent↗
PubMed1994

O6-methylguanine-DNA methyltransferase activity in the human lung persists with advancing age.

O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in the repair of DNA lesions induced by alkylating carcinogens in a wide range of animals. To determine the relationship between DNA repair activity and tumor susceptibility with advancing age the activity of MGMT was measured in normal lung tissue extracts from 66 patients with primary or metastatic lung cancer obtained at surgery. The age of the patients whose lung MGMT activity was measured ranged from 40 to 79 years (males) and from 40 to 80 years (females), and the values varied over 10-fold in both sexes (33 males and 33 females). Our results indicate that the MGMT enzyme protein is expressed at appreciable levels throughout life, and on age-associated rapid decline is not a feature in the human lung. Thus, any age-associated increase in lung cancer incidence cannot be ascribed to any change in MGMT activity. In order to assess other possible factors which might exert a modulating influence we examined the MGMT activity in relation to sex, tumor type and smoking. However, in none of these cases was any significant correlation evident.

Adenocarcinoma↗
PubMed1994

[A case of primitive neuroectodermal tumor from rib].

Primitive Neuroectodermal Tumor (PNET) is a small round cell malignancy arising in bone and soft tissue. With the progress of immunohisto-chemical and ultrastructural studies, the tumor has getting attention. We report a rare case of PNET arising from rib. A 19-year-old man was admitted to our hospital complaining of chest and back pain. The tumor arised from 5th rib and en bloc resection was performed. Pathological diagnosis was PNET. After the operation, he is doing well, except being treated with chemotherapy (T9-protocol).

Adult↗
PubMed1993

O6-methylguanine-DNA methyltransferase protects against nitrosamine-induced hepatocarcinogenesis.

We previously generated transgenic C3H/HeN mice by introducing the Escherichia coli O6-methylguanine-DNA methyltransferase (MGMT, DNA-O6-methylguanine:protein-L-cysteine S-methyltransferase, EC2.1.1.63) gene, ada, attached to the Chinese hamster metallothionein I gene promoter. One transgenic mouse line expressing both ada-specific mRNA and Ada protein could be propagated over many generations in a homozygous state with respect to the integrated DNA. Liver extracts from transgenic homozygous mice have consistently demonstrated about 3 times the control activity of normal mice. Furthermore, in the transgenic homozygotes treated with ZnSO4, activity is increased to 6-8 times the normal level in mice and is equivalent to that for man. To examine whether these increased levels of MGMT activity can actually decrease the susceptibility of animals to N-nitroso compounds, we studied liver carcinogenesis in our transgenic mice expressing high amounts of MGMT. Groups of transgenic and nontransgenic mice, each comprising about 200 suckling animals (14 +/- 1 days old), were divided each into eight subgroups, providing paired groups of transgenic and nontransgenic mice. They received an i.p. injection of ZnSO4 to induce MGMT, and 10 hr thereafter were given an i.p. injection of either dimethylnitrosamine or diethylnitrosamine. Liver tumor development was quantitatively assessed at 7-11 months. Here, we report statistically significant reduction of tumor formation in transgenic mice of four of the six paired groups that received treatment. The remaining two demonstrated results in line with dose dependence. Therefore, our data indicate that MGMT can indeed protect animals from low-dose exposure to environmental alkylating carcinogens.

Animals↗
PubMed1993

Dynamic light scattering of aqueous solutions of linear aggregates induced by thermal denaturation of ovalbumin.

Dynamic light scattering measurements were performed on dilute aqueous solutions of native ovalbumin (OA) and on those of linear OA aggregates induced by thermal denaturation at low ionic strength and neutral pH. The weight-average molecular weight MW of four aggregates tested ranged from 1,700,000 to 5,500,000. The translational diffusion coefficient D0 of native OA at infinite dilution was estimated as 8.70 x 10(-7) cm2/s, which gave 56.0 A as the diameter of the rigid spherical particle. The intensity autocorrelation function of linear OA polymers was analyzed with the cumulant method to obtain the first cumulant gamma e. The dependence of gamma e on the scattering vector q at very low polymer concentration was found intermediate between those of a flexible chain and a rigid rod. The translational diffusion coefficient Dtr [identical to (gamma e/q2)q-->0] was in proportion to M-0.55W, and the magnitude was in good agreement with a value calculated from the wormlike cylinder model with values of three parameters determined in an earlier study, ML = 1600 A-1, d = 120 A, and Q = 230 A, where ML, d, and Q are the molecular weight per unit length, diameter, and persistence length, respectively. Based on these results, a new model, to be called as the dimer model, was proposed to interpret the formation mechanism of linear OA polymers induced by thermal denaturation.

Animals↗
PubMed1993

Magnetic resonance imaging of xanthomatous meningioma.

A case of meningioma with extensive xanthomatous metaplasia occurring in the left frontal convexity of a 37-year-old woman is reported. The tumour was demonstrated as a hypodense mass with minimal enhancement on CT. Our findings suggest that magnetic resonance imaging may provide a clue to the diagnosis of meningiomas with extensive xanthomatous metaplasia when CT is less specific.

Adult↗