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K Kohno

Publications and source records attributed to K Kohno.

At least 55 records · Page 3Linked to original sources
PubMed1991

Multiple analysis of tyrosine hydroxylase and calmodulin distributions in the forebrain of the rat using a microphotometry system.

Immunohistochemical distributions of tyrosine hydroxylase and calmodulin in the rat forebrain were analyzed quantitatively to confirm our previous results that the activities of central catecholamine-synthesizing enzymes are regulated by a calcium-calmodulin-dependent system. The adjacent slices of adult rat brain were stained immunohistochemically for tyrosine hydroxylase and for calmodulin, and the distributions and amounts of these proteins were measured by a fluorescence microphotometry system that was developed in our laboratory. Immunohistochemical fluorescence intensity was measured stepwise at 40 microns intervals through a 6 microns phi (on the slice) pin hole. Each stained brain slice was divided into approximately 100,000 areas, and measured for fluorescence intensity and displayed two- and three-dimensionally. Immunoreactive staining of tyrosine hydroxylase and calmodulin was observed in almost all areas of the brain, but its intensity varied. The relatively high levels of calmodulin could be observed in brain regions with high levels of tyrosine hydroxylase distribution, though high levels of tyrosine hydroxylase could not always be observed in brain regions where high levels of calmodulin were distributed. In the present study, high levels of tyrosine hydroxylase and calmodulin were distributed in the nucleus accumbens septi and the lateral part of the neostriatum regions in which the amount of dopamine was increased by the intraventricular administration of calcium. These findings suggest that the synthesis of central catecholamines is regulated by a calcium-calmodulin-dependent system.

Animals↗
PubMed1991

Enhancement of antitumour activity of etoposide by dihydropyridines on drug-sensitive and drug-resistant leukaemia in mice.

We recently reported that six 1,4-dihydropyridine derivatives out of 57 screened effectively over-came vincristine (VCR)-resistance in VCR-resistant (P388/VCR) leukaemia-bearing mice when the dihydropyridines and VCR were administered intraperitoneally (i.p.). Furthermore, among the six dihydropyridine derivatives, two compounds, NK-250 and NK-252, most effectively overcame VCR-resistance while exhibiting relatively low calcium antagonistic activity and toxicity. In this study, we examined whether NK-250 and NK-252 could potentiate the antitumour activities of etoposide in mice with drug-sensitive (P388/S) or VCR-resistant (P388/VCR) leukaemia cells when the anticancer agents and tumour cells were administered by various routes. In both groups of mice inoculated i.p. with P388/S- and P388/VCR-leukaemia cells, the oral (p.o.) administration of NK-250 combined with i.p. or intravenously (i.v.) administration of etoposide (ip-po-ip trials and ip-po-iv trials) dramatically potentiated the antitumour activity of etoposide. Although etoposide alone was less effective in treating mice inoculated i.v. with P388/S- and P388/VCR-leukaemia cells, p.o. administration of NK-250 combined with i.p. or i.v. administration of etoposide (iv-po-ip trials and iv-po-iv trials) potentiated the antitumour activity of etoposide to similar levels as in treating mice inoculated i.p. with leukaemia cells. These 1,4-dihydropyridines were therefore highly effective in potentiating anticancer drugs against both drug-sensitive and drug-resistant tumours.

Administration, Oral↗
PubMed1991

Natural human interferon-alpha augments interleukin-2 production by a direct action on the activated IL-2-producing T cells.

The production of interleukin-2 (IL-2) by Concanavalin A (ConA)-stimulated peripheral blood leukocytes (PBL) from normal human donors was enhanced by natural human interferon-alpha (IFN-alpha). The mechanism of the action of IFN-alpha on IL-2 production was studied further using cloned human leukemic T-cell lines, which produce IL-2 spontaneously and/or after mitogen stimulation. It was found that IFN-alpha alone did not stimulate IL-2 production, but increased it in the activated cells. The ability of IFN-alpha to increase IL-2 production was abrogated by the treatment of IFN-alpha preparations with specific anti-IFN-alpha antibody, and the induced IL-2 activity was completely inhibited by monoclonal antibody against human IL-2. We suggest that the augmentation by IFN-alpha of IL-2 production in the activated T cells may be one of the mechanisms attributable to the immunotherapeutic action of IFN-alpha.

Clone Cells↗
PubMed1991

Targeted introduction of a diphtheria toxin-resistant point mutation into the chromosomal EF-2 locus by in vivo homologous recombination.

We have introduced a specific point mutation into the gene for chromosomal elongation factor 2 (EF-2) in Chinese hamster ovary cells (CHO-K1) by in vivo homologous recombination. To obtain a selectable construct for gene-targeting, we modified a diphtheria toxin-resistant mutant EF-2 gene (Gly717 to Arg) by deleting its promoter and first exon so that homologous recombinants could be distinguished from randomly integrated transformants, and also by inserting a second positive selection marker, the neomycin-resistance gene, into the 3'-flanking region to increase the selective accuracy. More than 80% of the clones surviving after selection for resistance to both the toxin and neomycin were the desired homologous recombinants in which the wild-type, toxin-sensitive EF-2 gene was replaced by the modified gene giving resistance to both the toxin and neomycin. This result shows that the specific point mutation was co-introduced with a second selective marker into an endogenous chromosomal gene and that the modified gene was expressed.

Animals↗
PubMed1991

Foramen magnum decompression for syringomyelia associated with basilar impression and Chiari I malformation--report of three cases.

Anterior or posterior decompression of the foramen magnum was performed in three patients with syringomyelia associated with basilar impression and Chiari I malformation. The operative results were evaluated using the pre- and postoperative magnetic resonance (MR) images. Two patients with combined anterior and posterior cervicomedullary compression due to basilar impression and tonsillar descent received suboccipital craniectomy, upper cervical laminectomy, and dural plasty without any intradural manipulations via the posterior approach. One patient with prominent anterior cervicomedullary compression due to basilar impression and a sharp clivoaxial angle was operated on by the transoral anterior approach. Postoperatively, all patients showed a sustained shrinkage of the syrinx and rounding of the flattened cerebellar tonsils. Two patients showed upward movement of the herniated tonsils. All patients had improved symptoms during 2-4 years follow-up. Treatment of syringomyelia associated with basilar impression and Chiari I malformation requires more efficient decompressive procedures at the foramen magnum based on neurological and MR findings.

Adult↗
PubMed1991

[Mechanisms of resistance to DNA topoisomerase II inhibitors].

Cytotoxicity of anticancer drugs are depended on cellular differences of drug transport processes, drug metabolism or proliferation process including DNA synthesis. Thus, resistance to anticancer drugs is likely due to many cellular changes. Mechanisms of resistance to anticancer drugs have been studied with cells selected for their ability to grow in the presence of drugs. In this paper, the mechanisms of cellular resistance to DNA topoisomerase II inhibitors was described.

Animals↗
PubMed1991

Induced natural killer-like cytotoxic function in the TCR delta-1 positive human leukemic T-cell lines.

Four human leukemic T-cell lines with a T-cell receptor (TCR) gamma/delta heterodimer (MOLT-13, MOLT-14, and PEER) or beta/delta-heterodimer (DND-41), as determined by monoclonal antibody (mAb), TCR delta-1, were identified by phenotypic and genotypic analysis. Two similar human leukemic T-cell lines with a TCR alpha/beta heterodimer (CCRF-CEM and MOLT-16) were used in this study. Natural killer (NK)-like activity was investigated in the TCR gamma/delta+ cell lines and TCR alpha/beta+ cell lines induced by exogenous recombinant human IL-2 (rIL-2), or phorbol 12-myristate 13-acetate (PMA). Three (MOLT-13, MOLT-14, and DND-41 cells) of the four TCR delta-1 positive cell lines, after 48 h treatment with exogenous rIL-2 or PMA (except DND-41), showed NK-like activity to K562, but not to Daudi cells. Furthermore, when MOLT-13, MOLT-14, and DND-41 cells were co-cultured with rIL-2 or PMA, 5-20% of these cells expressed the beta-subunit of IL-2R. Treatment with rIL-2 or PMA induced the expression of the beta-subunit of IL-2R, which in turn induced IL-2R. Subsequently these cells could transmit the signal for the induction of NK-like cytotoxicity. These findings indicate that changes in the beta-subunit of IL-2R expression may be responsible for the target cell specificity of activated effector cells.

CD4 Antigens↗
PubMed1991

Hepatocellular carcinoma presenting with pyrexia and leukocytosis: report of five cases.

In the past 26 years we have encountered five patients with primary liver malignancy clinically characterized by high remittent fever and leukocytosis mimicking liver abscess. Two patients underwent exploratory laparotomy, and drainage was carried out in another. The clinical courses went rapidly downhill. The liver was cirrhotic in two patients. The interior of the main mass was almost totally necrotic in four cases. Histologically, the malignant cells in the main portion resembled sarcoma, but in some areas cells appeared epithelial with eosinophilic cytoplasm and were in a trabecular arrangement, except for one case not subjected to autopsy in which histological study was inadequate because of extensive necrosis. It seems that these neoplasms were very poorly differentiated hepatocellular carcinomas rather than combinations of sarcoma and hepatocellular carcinoma. These patients, therefore, may represent a distinct clinicopathological type of hepatocellular carcinoma that is very rare in Japan but perhaps more common in South Africa, where similar cases have been clinically described in larger numbers.

Adult↗
PubMed1991

Potentiation of etoposide and vincristine by two synthetic 1,4-dihydropyridine derivatives in multidrug-resistant and atypical multidrug-resistant human cancer cells.

Newly synthesized 1,4-dihydropyridine derivatives had been screened to determine whether they could overcome vincristine (VCR)-resistance in VCR-resistant (P388/VCR) leukemia-bearing mice, and six compounds had strong reversing ability among the screened compounds. We further determined whether NK-250 and NK-252 among the six compounds could potentiate cytocidal activities of etoposide (VP16) as well as VCR against both multidrug-resistant (MDR) cell line (VJ-300) and atypical MDR cell line (KB/VM-4). Both VJ-300 and KB/VM-4 were derived from the same parental human cancer KB cell line: VJ-300 cells showed enhanced expression of a MDR-specific glycoprotein of molecular weight of 170,000 Da (gp170) while KB/VM-4 cells were selected as teniposide (VM26)-resistant cell line with no expression of gp170. NK-250 and NK-252 potentiated the cytotoxic action of VCR about 2- to 10-fold against KB and KB/VM-4 cells, and they almost completely reversed VCR-resistance in VJ-300 cells. By contrast, NK-250 and NK-252 potentiated the cytotoxic action of VP16 about 2-fold against KB cells while they reversed 5- to 10-fold VP16-resistance in both VJ-300 and KB/VM-4 cells. The reversal effect by NK-250 and NK-252 of VCR-resistance in VJ-300 cells appeared to be due to enhanced cellular accumulation of radioactive VCR through interaction to 170-kDa P-glycoprotein. The potentiation effects by these dihydropyridines of VCR and VP16 on KB or KB/VM-4 cells also appeared to be due to enhanced accumulation of radioactive VP16 or VCR, but the effects might be mediated through other mechanisms, plausibly enhanced cellular uptake of the drugs.

Antineoplastic Agents↗
PubMed1991

[Massive hemorrhage induced by tracheo-innominate artery fistula in two infants].

Two cases of massive hemorrhagic shock induced by tracheo-innominate artery fistula are reported. The first case is a 4 year-old girl with encephalitis under prolonged mechanical ventilation. The second case is a 6 year-old tracheostomized girl with mental and motor retardation of congenital origin who has been taken care of at her home. This catastrophic complication is usually caused by long term placement of tracheostomy tube with the cuff inflated especially in malnourished pediatric patients. The cuff pressure is apt to be concentrated on one side of the tracheal wall especially in mechanically ventilated immobilized patients. Although this complication is rare because cuffed tube is currently avoided in pediatric patient, sophisticated care should be taken in managing tracheostomized patients.

Brachiocephalic Trunk↗
PubMed1990

Tissue-specific enhancer of the human multidrug-resistance (MDR1) gene.

Identification of cis-regulatory sequences is a first step in analyzing the regulation of the human multidrug-resistant 1 (MDR1) gene which encodes the 170-kilodalton membrane P-glycoprotein in normal tissues and tumor cells. We have studied several overlapping genomic clones containing the 5'-flanking region of the gene. These clones span about 30 kilobases (kb) of contiguous DNA containing 10 kb of the gene and 20 kb of the 5'-flanking sequence. The nucleotide sequence of the first exon and the 2 kb preceding the exon were determined. DNA sequences containing the 5'-flanking regions were linked to the chloramphenicol acetyltransferase (CAT) gene. For transient CAT assay, we have employed six cell lines, including human cancer KB, vincristine-resistant VJ-300 derived from KB, mouse adrenal tumor Y-1, African green monkey kidney CV-1, mouse fibroblast NIH3T3, and human adrenal carcinoma SW-13 cells. Promoter activity was very weak regardless of the length of the promoter region in mouse adrenal tumor Y-1 and monkey kidney CV-1 cells, in which endogenous P-glycoprotein was expressed. Introduction of a 700-base genomic DNA fragment from a site located at 10 kb far upstream of the initiation site increased the transcription of the CAT gene in Y-1, CV-1, and SW-13 cells. However, no significant increase in the CAT activity could be observed in NIH3T3, KB, and VJ-300 cells. This fragment markedly augmented the expression of the CAT gene regardless of orientation or position, and it acted in a cell type-specific manner even with heterogenous promoters. Our present study suggests that the 700-base pair fragment may carry a tissue-specific transcriptional enhancer that is active in at least some adrenal and kidney-derived cell lines.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Activities of newly synthesized dihydropyridines in overcoming of vincristine resistance, calcium antagonism, and inhibition of photoaffinity labeling of P-glycoprotein in rodents.

Newly synthesized 1,4-dihydropyridine derivatives (NK-compounds) were screened to determine whether they could overcome vincristine (VCR) resistance in VCR-resistant (P388/VCR) leukemia-bearing mice. Among the 57 NK-compounds examined, six compounds had strong reversing ability (Grade A), 18 partially overcame the resistance (Grade B), and 33 did not reverse the resistance (Grade C). The ability to overcome resistance varied considerably with the nature of substituents at positions 3.5 of the 1,4-dihydropyridine, and the most suitable substituents were the pyridylalkyl-including esters. Calcium antagonistic activity of NK-compounds having pyridylalkyl-including esters at positions 3.5 and dithiene ring at position 4 of the 1,4-dihydropyridine was greater than in those compounds having the dioxene ring at position 4. NK-242, which was assessed at Grade A and had no calcium antagonistic activity, improved therapeutic effects in both VCR-sensitive (P388/S) leukemia- and P388/VCR leukemia-bearing mice when combined with VCR. Fourteen NK-compounds were screened to determine whether they could inhibit photoaffinity labeling of the P-glycoprotein (Mr 170,000 glycoprotein) in a multidrug-resistant cell line by [3H]azidopine. All six compounds of Grade A and two of the three compounds of Grade B almost completely inhibited the labeling of Mr 170,000 glycoprotein at 1 to 10 microM. Thus there was a good correlation between the ability to reverse VCR resistance in vivo and the inhibition of photoaffinity labeling of Mr 170,000 glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Expression of ret proto-oncogene in human neuroblastomas.

We examined the expression of ret proto-oncogene (proto-ret) in surgically resected human neuroblastomas. Slot blot RNA hybridization revealed that all 29 neuroblastomas examined expressed the proto-ret, the relative intensity of the hybridization ranging from 1 to 48. No correlation was found between the level of expression of proto-ret and the clinical stage. The level of expression was also not correlated with N-myc amplification, the patient's age or the histological type of the tumor. Based on the previous finding that proto-ret expression is very rarely detected in tumor cell lines other than those of neuroblastoma, proto-ret expression was suggested to be a characteristic of neuroblastomas, and possibly to be involved in the genesis of neuroblastomas.

Actins↗
PubMed1990

Reversal by two dihydropyridine compounds of resistance to multiple anticancer agents in mouse P388 leukemia in vivo and in vitro.

We investigated whether two representative 1,4-dihydropyridine derivatives, NK-250 and NK-252, could potentiate the antitumor activity of multiple anticancer agents including vincristine (VCR), vinblastine, vindesine and actinomycin D in drug-resistant tumor cells and their parental drug-sensitive tumor cells. NK-250 and NK-252 at 5-10 microM almost completely reversed VCR resistance in cultured VCR-resistant P388/VCR cells derived from the mouse drug-sensitive P388/S leukemia cell line and also potentiated the cytocidal activity of VCR in drug-sensitive P388/S cells. NK-250 and NK-252 at 1-10 microM inhibited the photoaffinity labeling by [3H]azidopine of the cell-surface 170,000-molecular-weight P-glycoprotein. In chemotherapeutic experiments with leukemia-bearing mice, NK-250 or NK-252 was orally administered in combination with different drugs of the MDR phenotype administered intraperitoneally. The antitumor activity of the various combinations was found to be augmented in mice bearing P388/S- and P388/VCR-leukemia. Among the combinations examined, the combination of NK-250 and VCR was the most effective. These two 1,4-dihydropyridines, NK-250 and NK-252, are unique compounds because they were effective not only in circumventing the drug resistance, but also in potentiating the action of antitumor drugs against drug-sensitive tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1979

A case of double pylorus.

Doubling of the pyloric channel is one of the rare anomalies of the intestinal tract. There have been 23 cases of double pylorus that we have been able to find in the literature. As the etiologic aspects of double pylorus the majorities of the cases were thought to be acquired lesions from ulcer disease except three cases. We present a case of double pylorus which seems to be acquired lesion, with a review of the literature.

Aged↗