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Biomedical subjects

K Mitani

Publications and source records attributed to K Mitani.

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

A simple preparation of mycoplasmal DNA template for PCR from biological samples using effective surfactants.

To prepare mycoplasmal DNA template for PCR from biological samples rapidly and easily, surfactants which can solubilize cell membranes effectively were investigated. 3-[3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) was considered an effective surfactant. This surfactant could solubilize mycoplasma cell membrane without suppressing the polymerase reaction. In addition, proteinase K treatment played an important role in preparing mycoplasmal DNA template from a simulated biological sample. It was therefore considered that a combination of proteinase K- and CHAPS- added lysis buffer would be more useful in preparing mycoplasmal DNA template. We could detect PCR products by using the lysis buffer with a simulated lung emulsion sample containing mycoplasma organisms at 10(4) CFU per gram.

Animals↗
PubMed1996

Genetic properties of Mycoplasma mycoides subspecies mycoides LC strains isolated from a goat in Japan in 1991.

Field isolated Mycoplasma strains LG1 and SF1 were isolated from the lung and leg joint fluid of a goat, respectively in Japan in 1991. These strains were closely related and had the following biochemical properties: glucose was metabolized, arginine and urea were not hydrolyzed, tetrazolium was reduced, phosphatase produced, and casein and coagulated serum were digested. Serologically, these strains cross-reacted with three Mycoplasma species [M. mycoides subsp. mycoides (Mmm), M. mycoides subsp. capri, and M. sp. Group 7]. From the above results, the field isolates were considered to be Mmm. In addition, DNA-DNA relatedness between the field isolates and other Mycoplasma species called the "mycoides cluster" was determined, and a recently developed PCR method was also used for mycoplasmal identification. From these results, the field isolates were identified as Mmm LC type.

Animals↗
PubMed1996

Increased Evi-1 expression is frequently observed in blastic crisis of chronic myelocytic leukemia.

Evi-1 is a transforming gene originally identified in a common integration site of murine leukemia retrovirus and mapped in human chromosome 3q26. It is not normally expressed in either human or murine hematopoietic cells, but is overexpressed in retrovirus-induced murine myeloid leukemias as well as human myeloid leukemias with 3q26 abnormalities, and thus thought to be responsible for both human and murine leukemogenesis. In this study, possible involvement of the Evi-1 gene in human leukemias was evaluated by Northern blot analysis in a total of 73 patients with various types of leukemias. We found that increased expression of the Evi-1 gene was most frequently observed in patients with CML in blastic crisis. It was found in 10 of 14 (71.0%) samples from CML in blastic crisis, three of 15 (20.0%) from acute myelocytic leukemia, three of 11 (27.3%) from MDS-derived leukemia, and one of 11 (9.1%) from acute lymphoblastic leukemia. Among 18 patients showing increased Evi-1 expression, none of 17 informative patients showed cytogenetic abnormalities involving 3q26. In addition, Southern blot analysis revealed neither amplification nor rearrangements of the Evi-1 gene in 11 Evi-1-positive patients whose DNA samples were available. Our results suggest that increased expression of the Evi-1 gene may play an important role in development of human leukemias, especially in progression from chronic phase to blastic crisis of CML even without 3q26 abnormalities.

Adult↗
PubMed1996

[An unusual autopsy case of corticobasal degeneration--with special reference to clinicopathological differentiation from progressive supranuclear palsy and slowly progressive aphasia].

We report an unusual autopsy case of corticobasal degeneration. The patient was male who was 67 years old at the time of his death. He developed clumsiness of his right hand at age 65. Neurological examination at age 66 revealed supranuclear ophthalmoplegia of upward gaze and parkinsonism. Progressive supranuclear palsy was suspected. The patient's clinical course was rapidly progressive. Dementia developed nine months after the onset of the disease, and the patient manifested apallic syndrome at 21 months and died of pneumonia at about 25 months. At autopsy the brain weighed 1370g. Macroscopic examination revealed prominent atrophy of the anterior and parietal lobes, particularly of the pars opercularis in the left inferior frontal gyrus, and there was marked depigmentation of the substantia nigra. Histological examination showed neuronal loss, glial proliferation, spongy state, and ballooned neurons in the frontal and parietal lobes. Neuronal loss with glial proliferation was conspicuous in the striatum, pallidum, thalamus, and substantia nigra. There was slight neuronal loss in the dentate nucleus and locus ceruleus. Staining by Gallyas-Braak method revealed massive appearance of argyrophilic threads. This case is important in terms of the clinical differentiation from progressive supranuclear palsy, and is also interesting in regard to the pathological correlation with slowly progressive aphasia.

Aged↗
PubMed1996

[An autopsy case of late-onset chorea].

Senile chorea has been an ill-defined clinical entity because of the difficulty of differentiating it from Huntington's disease (HD) of late-onset type. The gene specific for HD has recently been found to contain an abnormal (CAG)n trinucleotide repeat which allows it to be differentiated from the other conditions. Our case of late-onset chorea was differentiated from HD by PCR. An 80-year-old man had experienced gradually increasing chorea of his tongue, arms and legs for 4 years, but had not exhibited character changes, mental symptoms or dementia. He died of pneumonia at 84 years. The pathological findings in this case were different from those of HD. The brain weighted 1220 g, and did not show striatal atrophy or neuronal loss. The most remarkable findings were numerous foamy spheroids scattered in the caudate and putamen and proliferation of fibrous astrocytes within the thin myelinated fiber bundles and in the neuropil. Similar findings were reported by Freidman et al. (1990). Although it is debatable whether this finding was responsible for the development of the chorea, this case should contribute to our understanding of senile chorea as a clinicopathological entity.

Age of Onset↗
PubMed1996

Connection between NO(x) and SO(x) collected from the Japanese cedar tree and Pollinosis.

In this study, substances of air pollution (NO3-, SO4(2-)) which were collected from the surface of the Japanese cedar flowering parts and pollens in one mountainous and two urban areas were measured by ion chromatography monthly from November '87 to March of '88 and '90 to '91. A questionnaire study of nasal symptoms and school physical examinations were performed on about 400 junior high schools students in two districts (urban area and mountainous area) in March '87 and '91. The results of this research are as follows: i) The quantity of NO4 collected from the pollen of Japanese cedars in the urban and municipal park areas was 2.0 and 3.0 times greater, respectively, than in the mountainous area. The respective concentrations of SO2- were 5 and 2 times higher than the concentration in the mountainous area. ii) The results of a questionnaire of nasal symptoms and of the physical examinations at two junior high schools in the different districts showed a lower incidence of pollinosis in the mountainous area than in the urban area. Comparatively, the percentage of pollinosis in the mountainous area rose from 17.0% in 1987 to 25.0% in 1991, corresponding to a similar rise in the number of diesel vehicles running in the area.

Air Pollutants↗
PubMed1996

Abnormal expression of Evi-1 gene in human leukemias.

The human Evi-1 gene located on chromosome 3q26, encodes a zinc finger protein that functions as a transcription factor. It was frequently overexpressed in leukemias having 3q26 abnormalities such as t(3;3)(q21;q26) and inv(3)(q21 q26), and subjected to structural alteration in t(3;21)(q26;q22). In addition, recent studies indicated that several cases of leukemias without 3q26 abnormalities also expressed Evi-1 gene. In this study we present another case of structural alteration of Evi-1 gene in a case of inv(3)(q21 q26), in which Evi-1 was truncated and a shorter form of Evi-1 protein was expressed upon rearrangement of the gene. We also studied expression of the Evi-1 gene in a variety of leukemias by northern blot analysis. Evi-1 was overexpressed not only in leukemias with 3q26 abnormalities, but, in those without 3q26 abnormalities, especially in blast crisis of CML. Our result also supports an idea that Evi-1 is a relevant oncogene whose overexpression or structural changes might play a crucial role in development of human leukemias.

Adult↗
PubMed1995

Efficient regulation of gene expression by adenovirus vector-mediated delivery of the CRE recombinase.

We have constructed an E1-defective adenovirus (Ad) vector designated AdCAG-Cre containing the Cre recombinase gene derived from bacteriophage P1 under control of the cytomegalovirus immediate early enhancer-chicken beta-actin hybrid (CAG) promoter. We examined the Cre-loxP-based recombination by this Ad vector in C2C12 cells bearing a reporter gene construct CAG-CAT-Z, which directs expression of the E. coli lacZ gene upon Cre-mediated excision of the CAT gene located between the CAG promoter and the lacZ gene. Nearly 100% of these cells were shown to start to produce beta-galactosidase after infection with the AdCAG-Cre vector at MOI 100. On the basis of this result, we discuss the possible use of the AdCAG-Cre vector to manipulate the gene expression in mammalian cells.

Adenoviruses, Human↗
PubMed1995

TPO/c-mpl ligand induces tyrosine phosphorylation of multiple cellular proteins including proto-oncogene products, Vav and c-Cbl, and Ras signaling molecules.

Thrombopoietin (TPO)/c-mpl ligand is a hematopoietic growth factor that stimulates proliferation and maturation of megakaryocytes. To analyze the signaling pathway downstream of the c-mpl product, we used a human megakaryoblastic cell line, Mo7e, that has been proved to be responsive to TPO in terms of DNA synthesis. In this study, we found that TPO treatment resulted in tyrosine phosphorylation of Jak-2 kinase. Moreover, it was revealed that several functional molecules involved in the Ras signaling pathway, Shc and Sos, were phosphorylated by treatment with TPO. Finally, tyrosine phosphorylation of the proto-oncogene products, Vav and c-Cbl, has been proved to be induced by TPO. These results suggest that TPO could activate several signaling pathways including the Jak/Stat pathway, the Ras pathway and possibly another pathway involving the c-Cbl proto-oncogene product.

Cell Cycle Proteins↗
PubMed1995

The AML1/Evi-1 fusion protein in the t(3;21) translocation exhibits transforming activity on Rat1 fibroblasts with dependence on the Evi-1 sequence.

The t(3;21) (q26;q22) chromosomal translocation associated with blastic crisis of chronic myelogenous leukemia (CML) results in the formation of a chimeric protein fusing the amino-terminal DNA-binding domain encoded by the AML1 gene to the carboxyl-terminal-encoding portion of the Evi-1 gene. In order to evaluate transforming activity of this protein, AML1/Evi-1 was introduced into Rat1 fibroblasts. Cells expressing the fusion product formed macroscopic colonies in soft agar, indicating that AML1/Evi-1 is a transforming gene. It was also demonstrated that introduction of AML1/Evi-1 into the Rat1 clones harboring BCR/ABL also conferred enhanced capacity for anchorage independent growth. Analyses of deletion mutants of AML1/Evi-1 revealed that removal of the second zinc finger domain within the Evi-1 sequence totally abrogated the ability of AML1/Evi-1 to transform Rat1 cells. We showed that the transforming effect is correlated with the AP-1 activation induced by AML1/Evi-1. Furthermore, we demonstrated that c-jun is transcriptionally activated in Rat1 cells transformed by AML1/Evi-1, suggesting that c-jun expression is under control of AML1/Evi-1. These results indicate that the oncogenic effect of the t(3;21) translocation is caused by the generation of a chimeric transcriptional factor and that AML1/Evi-1 could perform a pivotal role in leukemic progression of CML.

3T3 Cells↗
PubMed1995

Alternative splicing and genomic structure of the AML1 gene involved in acute myeloid leukemia.

We previously isolated the AML1 gene, which is rearranged by the t(8;21) translocation in acute myeloid leukemia. The AML1 gene is highly homologous to the Drosophila segmentation gene runt and the mouse transcription factor PEBP2 alpha subunit gene. This region of homology, called the Runt domain, is responsible for DNA-binding and protein--protein interaction. In this study, we isolated and characterized various forms of AML1 cDNAs which reflect a complex pattern of mRNA species. Analysis of these cDNAs has led to the identification of two distinct AML1 proteins, designated AML1b (453 amino acids) and AML1c (480 amino acids), which differ markedly from the previously reported AML1a (250 amino acids) with regard to their C-terminal regions, although all three contain the Runt domain. The large C-terminal region common to AML1b and AML1c is suggested to be a transcriptional activation domain. AML1c differs from AML1b by only 32 amino acids in the N-terminal. Characterization of the genomic structure revealed that the AML1 gene consists of nine exons and spans > 150 kb of genomic DNA. Northern blot analysis demonstrated the presence of six major transcripts, encoding AML1b or AML1c, which can all be explained by the existence of two promoters, alternative splicing and differential usage of three polyadenylation sites. A minor transcript encoding AML1a which results from alternative splicing of a separate exon can be detected only by reverse transcription-polymerase chain reaction amplification. The distinct proteins encoded by the AML1 gene may have different functions, which could contribute to regulating cell growth and/or differentiation through transcriptional regulation of a specific subset of target genes.

Alternative Splicing↗
PubMed1995

Increased expression of AML1 during retinoic-acid-induced differentiation of U937 cells.

The AML1 gene on chromosome 21 is disrupted in the (8;21)(q22;q22) and (3;21)(q26;q22) translocations associated with myelogenous leukemias and encodes a DNA binding protein. From the AML1 gene, three proteins, AML1a, AML1b and AML1c, are produced by alternative splicings. We previously showed that AML1 is potentially involved in myeloid cell differentiation. Here we analyzed the expression of AML1 in myeloid cell lines. It was revealed that AML1b and AML1c are the major AML1 proteins in these cell lines and that prior to morphological and functional differentiation, their expressions increase in U937 cells when treated with all-trans retinoic acid. These data suggest that the expression of AML1 is associated with myeloid cell differentiation.

Alternative Splicing↗
PubMed1995

The proto-oncogene product c-Cbl becomes tyrosine phosphorylated by stimulation with GM-CSF or Epo and constitutively binds to the SH3 domain of Grb2/Ash in human hematopoietic cells.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin (Epo) are hematopoietic growth factors that regulate proliferation and differentiation of hematopoietic cells. They elicit and control a cascade of biochemical events, the earliest of which is tyrosine phosphorylation of several cellular proteins. Grb2/Ash is composed of SH2 and SH3 domains. The SH2 domain binds to tyrosine-phosphorylated proteins, and the SH3 domains bind to proteins containing proline-rich regions. It is considered that Grb2/Ash functions as an adapter protein linking tyrosine kinases and Ras in downstream of receptors for growth factors in fibroblasts. However, the mechanisms of signal transduction through Grb2/Ash and the roles of proteins associated with Grb2/Ash remain to be determined in hematopoietic cells. By means of the binding experiments using the glutathione S-transferase fusion protein including the full-length Grb2/Ash, we have found that Shc and unidentified 130- and 135-kDa proteins are associated with Grb2/Ash and that they are tyrosine phosphorylated by treatment with GM-CSF or Epo in a human leukemia cell line, UT-7. We have purified the 130-kDa protein (pp130) using the glutathione S-transferase-Grb2/Ash affinity column. The amino acid sequence analysis of the three peptides derived from the in situ protease digestion of the purified pp130 showed that the pp130 was identical to the human c-cbl proto-oncogene product (c-Cbl). c-Cbl constitutively binds to the SH3 domain of Grb2/Ash both in vitro and in vivo but not to the SH2 domain of Grb2/Ash, and the binding of Grb2/Ash to c-Cbl or Sos was not altered by GM-CSF stimulation. Moreover, c-Cbl (pp130) becomes tyrosine phosphorylated rapidly and transiently depending on GM-CSF or Epo stimulation. These findings strongly suggest that c-Cbl is implicated in the signal transduction of GM-CSF or Epo in hematopoietic cells and that c-Cbl is involved in another signaling pathway different from the Ras signaling pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Disruption of the adenosine deaminase gene causes hepatocellular impairment and perinatal lethality in mice.

We have generated mice with a null mutation at the Ada locus, which encodes the purine catabolic enzyme adenosine deaminase (ADA, EC 3.5.4.4). ADA-deficient fetuses exhibited hepatocellular impairment and died perinatally. Their lymphoid tissues were not largely affected. Accumulation of ADA substrates was detectable in ADA-deficient conceptuses as early as 12.5 days postcoitum, dramatically increasing during late in utero development, and is the likely cause of liver damage and fetal death. The results presented here demonstrate that ADA is important for the homeostatic maintenance of purines in mice.

Adenosine Deaminase↗
PubMed1995

Rescue, propagation, and partial purification of a helper virus-dependent adenovirus vector.

Adenoviral vectors are widely used as highly efficient gene transfer vehicles in a variety of biological research strategies including human gene therapy. One of the limitations of the currently available adenoviral vector system is the presence of the majority of the viral genome in the vector, resulting in leaky expression of viral genes particularly at high multiplicity of infection and limited cloning capacity of exogenous sequences. As a first step to overcome this problem, we attempted to rescue a defective human adenovirus serotype 5 DNA, which had an essential region of the viral genome (L1, L2, VAI + II, pTP) deleted and replaced with an indicator gene. In the presence of wild-type adenovirus as a helper, this DNA was packaged and propagated as transducing viral particles. After several rounds of amplification, the titer of the recombinant virus reached at least 4 x 10(6) transducing particles per ml. The recombinant virus could be partially purified from the helper virus by CsCl equilibrium density-gradient centrifugation. The structure of the recombinant virus around the marker gene remained intact after serial propagation, while the pBR sequence inserted in the E1 region was deleted from the recombinant virus. Our results suggest that it should be possible to develop a helper-dependent adenoviral vector, which does not encode any viral proteins, as an alternative to the currently available adenoviral vector systems.

Adenoviruses, Human↗
PubMed1995

Cloning of several species of MLL/MEN chimeric cDNAs in myeloid leukemia with t(11;19)(q23;p13.1) translocation.

The t(11;19)(q23;p13.1) translocation is thought to play an important role in pathogenesis of myeloid leukemias in older patients. The MLL gene involved in other 11q23 abnormalities was also rearranged by this translocation. Screening of cDNA libraries of the t(11;19)(q23;p13.1)-carrying leukemic cells resulted in the isolation of several species of fusion cDNAs between the MLL gene and an unknown gene on 19p13.1, named MEN (myeloid eleven-nineteen translocation), which is ubiquitously expressed. Although the MLL gene was alternatively spliced, the fusion protein should contain an N-terminal half of the MLL, including AT hook motifs, that is fused to the MEN protein with a lysine-rich sequence, suggesting that the MLL/MEN fusion protein could be a chimeric transcription factor. The MLL/MEN fusion transcripts of 8.0 kb were detected in leukemic cells of two cases with the translocation. The MLL/MEN fusion was consistent in all three cases of the t(11;19)(q23;p13.1)-carrying leukemia examined by RNA-based polymerase chain reaction. These findings strongly suggest that the t(11;19)(q23;p13.1) results in the fusion formation encoding a new class of potential chimeric transcription factor that contributes to leukemogenesis of myeloid lineage.

Acute Disease↗
PubMed1995

An acute myeloid leukemia gene, AML1, regulates hemopoietic myeloid cell differentiation and transcriptional activation antagonistically by two alternative spliced forms.

The AML1 gene on chromosome 21 is disrupted in the (8;21)(q22;q22) and (3;21)(q26;q22) translocations associated with myelogenous leukemias and encodes a DNA binding protein. From the AML1 gene, two representative forms of proteins, AML1a and AML1b, are produced by alternative splicing. Both forms have a DNA binding domain but, unlike AML1b, AML1a lacks a putative transcriptional activation domain. Here we demonstrate that overexpressed AML1a totally suppresses granulocytic differentiation and stimulates cell proliferation in 32Dcl3 murine myeloid cells treated with granulocyte colony-stimulating factor. These effects of AML1a were canceled by the concomitant overexpression of AML1b. Such biological phenomena could be explained by our observations that (i) AML1a, which on its own has no effects as a transcriptional regulator, dominantly suppresses transcriptional activation by AML1b, and (ii) AML1a exhibits the higher affinity for DNA binding compared with AML1b. These antagonistic actions could be important in leukemogenesis and/or myeloid cell differentiation because more than half of myelogenous leukemia patients showed an increase in the relative amounts of AML1a.

Alternative Splicing↗