Biomedical subjects

S Kondo

Publications and source records attributed to S Kondo.

At least 19 recordsLinked to original sources

PubMed1992

Efficient amplification of Drosophila simulans copia directed by high-level reverse transcriptase activity associated with copia virus-like particles.

The number of retrotransposon copia per genome in Drosophila melanogaster cultured cells is two to three times higher than that in D. melanogaster embryo cells. Here, we have found that the genome of the related species, Drosophila simulans, contains in cultured cells more efficiently amplified copia DNA (approximately ten fold). Furthermore, we analyzed copia virus-like particles (VLPs) prepared from D. melanogaster and D. simulans cultured cells, which contain copia RNA and reverse transcriptase (RT) activity, and thus, play a major role in copia replication. The RT activity associated with the D. simulans VLPs was 25 times higher than that associated with the D. melanogaster VLPs. Taken together with the fact that copia is believed to transpose through an RNA intermediate, these results suggest that the amplification of copia DNA should relate to copia RNA-mediated transposition, and the higher RT activity associated with the D. simulans VLPs would lead to the efficient amplification of copia DNA. In a comparison between D. melanogaster and D. simulans copia nucleotide (nt) sequences, five nt substitutions, which cause the respective amino acid changes, were found in the copia RT-coding region. Polymerase chain reaction direct sequencing showed that these five substitutions are the vast majority in each Drosophila species. The substitutions, therefore, may be responsible for the high level of the RT activity associated with the D. simulans VLPs.

Amino Acid Sequence↗

PubMed1992

Taxonomic implication of the apparent undetectability of 3-deoxy-D-manno-2-octulosonate (Kdo) in lipopolysaccharides of the representatives of the family Vibrionaceae and the occurrence of Kdo 4-phosphate in their inner-core regions.

After conventional hydrolysis of lipopolysaccharides (LPSs), Kdo was not detectable by the periodate-thiobarbituric acid test in those of any member of Vibrionaceae except the gems Plesiomonas, but phosphorylated Kdo was demonstrated after strong-acid hydrolysis. Dephosphorylation, periodate oxidation, and methylation analysis of LPS preparations from 7 strains selected from all genera of Vibrionaceae, except Plesiomonas, showed that the inner-core region (unlike that in enteric Gram-negative bacteria) contains only one molecule of Kdo 4-phosphate 5-substituted with heptose, a constituent of the distal part of the core region, as in enteric bacteria. The undetectability of Kdo in LPS after conventional hydrolysis and the occurrence of phosphorylated Kdo in strong-acid hydrolysates and of Kdo 4-phosphate in the inner-core region are taxonomic characteristics of the family Vibrionaceae.

Hydrolysis↗

PubMed1992

Neurotransmitter release from synaptotagmin-deficient clonal variants of PC12 cells.

Synaptotagmin (p65) is an abundant synaptic vesicle protein of neurons and contains regions similar to the regulatory domain of protein kinase C. These domains are thought to be involved in calcium-dependent interaction with membrane phospholipids during exocytosis. To assess the functional role of synaptotagmin, synaptotagmin-deficient clonal variants of PC12 cells were isolated. All of the variant cells released catecholamine and adenosine triphosphate in response to elevated intracellular concentrations of calcium, which suggests that synaptotagmin is not essential for secretion of catecholamine and adenosine triphosphate from PC12 cells.

Adenosine Triphosphate↗

PubMed1992

Granulocyte colony-stimulating factor receptors on human acute leukemia: biphenotypic leukemic cells possess granulocyte colony-stimulating factor receptors.

Granulocyte colony-stimulating factor (G-CSF) receptors on the gated leukemic blast cells from newly diagnosed patients with acute leukemia or crisis of chronic myelogenous leukemia were investigated using flow cytometric detection. Surface marker analysis and cytochemical studies were conducted simultaneously to characterize the blast cells. Among 24 leukemia cases examined, G-CSF receptor-positive blast cells were detected in all 11 cases of acute myeloblastic leukemia even though the percentage range of positive cells was widely variable. On the other hand, they were not detected on the blast cells from patients with peroxidase-negative acute lymphoblastic leukemia with no myeloid surface antigens. However, G-CSF receptors were demonstrated in significant amounts on blast cells from 5 of 8 cases of peroxidase-negative acute leukemia expressing both myeloid and lymphoid surface antigens (biphenotypic leukemia). The percentage of blast cells positive for G-CSF receptors was significantly smaller in biphenotypic cases [33 +/- 14% (SD)] than in acute myeloblastic leukemia cases [65 +/- 22%] (P less than 0.01). The percentage expression of CD13 antigen by blast cells was significantly related to their percentage positivity for G-CSF receptors (rs = 0.50, P less than 0.05). These findings indicate that the distribution of flow cytometrically detectable G-CSF receptors on leukemic cells possessing myeloid characteristics may be related to the maturation process.

Antigens, CD↗

PubMed1992

Production of a unique multi-lamella structure in the nuclei of yeast expressing Drosophila copia gag precursor.

Drosophila retrotransposon copia produces virus-like particles (VLPs) in the nuclei of cultured Drosophila cells. The VLPs contain copia RNA and reverse transcriptase activity, and thus, play a major role in copia replication. Here we have expressed the copia gag polyprotein precursor in yeast. The precursor, which includes copia protease itself, showed correct autoprocessing to produce a unique multi-lamella structure in the nuclei of the yeast cells. This expression system should be useful for the analysis of nuclear localization of the major copia VLP protein, and furthermore, would provide important information concerning the mechanism of copia VLPs formation.

Animals↗

PubMed1992

Analysis of the close relationship between human astrocytoma-specific antigens detected by murine monoclonal antibodies and c-kit proto-oncogene product.

Tyrosine-specific phosphorylated proteins found exclusively on the cell surface of human astrocytomas were previously identified with murine monoclonal antibodies, designated as GA-17, GB-4 and GC-3. The purpose of this study was to further characterize the antigens and investigate the relationship between them and c-kit protooncogene product. We demonstrated that the antigens had protein kinase activity. Moreover, GA-17 reacted with c-kit protein expressed on the membrane of A172 human glioblastoma cells.

Antibodies, Monoclonal↗

PubMed1992

Folinic acid does not mobilize hemopoietic progenitors following repeated consolidation chemotherapy for acute leukemia.

Folinic acid (FA) has been reported to expand the pool of peripheral blood stem cells (PBSC) after chemotherapy. We evaluated the efficacy of FA for harvesting PBSC following cytotoxic chemotherapy in 4 patients with acute leukemia. After achieving a complete remission (CR), 3 courses of chemotherapy for a consolidation of the CR were administered to the patients. Two successive cycles of leukapheresis were performed during the recovery phase from consolidation chemotherapy, which consisted of an intermediate dose of cytosine arabinoside. For the second cycle of leukapheresis, FA was administered intravenously at a dose of 50 mg/day following consolidation. The yields of either mononuclear cells or burst-forming units-erythroid (BFU-E) were not affected by FA administration. In contrast, the yields of colony-forming units-granulocyte/macrophage (CFU-GM) were significantly decreased in all patients compared to the CFU-GM yields after the first cycle of leukapheresis (P = 0.032). Thus FA is considered not to be effective in expanding the peripheral blood progenitor pool when given in a fashion different from the original report.

Acute Disease↗

PubMed1992

Restoration of proliferating cell nuclear antigen (PCNA) complex formation in xeroderma pigmentosum group A cells following cis-diamminedichloroplatinum (II)-treatment by cell fusion with normal cells.

We examined the role of the factor deficient in xeroderma pigmentosum group A (XP-A) cells in the formation of proliferating cell nuclear antigen (PCNA) complex with DNA in the DNA repair process in human fibroblasts following cis-diamminedichloroplatinum (CDDP)-treatment. Immunofluorescence staining after methanol fixation was used to detect the PCNA complex formation. When quiescent normal cells were PCNA-stained at 3 h after 100 microM CDDP treatment for 1 h, almost all nuclei of the cells showed a punctuated staining pattern. On the other hand, nuclei of XP-A cells were not stained. These results were the same with the findings following 10J/m2 of ultraviolet light (UV)-irradiation. The quantitative analysis of the PCNA immunofluorescence intensity of normal cells revealed that the mean intensity was increased by 4.8 times by the CDDP-treatment and 6.1 times by the UV-irradiation, compared with that of untreated cells. The intensities among nuclei ranged widely in both treatments. In contrast, the mean intensity was not increased in XP-A cells by the same treatments. However, when XP-A cells were fused with normal cells with polyethylene glycol (PEG) treatment, the nuclei of the XP-A cells showed positive PCNA-staining following CDDP-treatment or UV-irradiation in almost all cases. These results suggest that the PCNA complex formation may play a role in the DNA repair process after the step where the factor deficient in XP-A cells is involved following CDDP-treatment as well as following UV-irradiation.

Cell Division↗

PubMed1992

Organ culture of psoriatic skin: effect of TGF-alpha and TGF-beta on epidermal structure in vitro.

Normal skin and uninvolved and involved psoriatic skin specimens were maintained in vitro in organ culture. The 3-4 mm punch-biopsied skin specimens were put freely into the culture medium with or without fetal calf serum, under an atmosphere of 95% O2 plus 5% CO2, and rotated at 60 rpm at 37 degrees C. In the serum-free culture medium (vitamin A-free) granular layers appeared in the involved psoriatic epidermis in culture. Addition of TGF-alpha caused normal skin and uninvolved and involved psoriatic skin specimens to become acanthotic and to degenerate easily almost to the full thickness of the epidermal layer in proportion to increasing concentrations of TGF-alpha as well as with the duration of the culture, but without disappearance of their granular layers. TGF-beta caused the normal skin and uninvolved psoriatic skin specimens to become thinned without disappearance of granular layers, but caused the involved psoriatic skin specimens to be thinned without appearance of granular layers in serum-containing medium or with their disappearance in the serum-free medium. TGF-beta also antagonized the acanthotic and degenerative effect of TGF-alpha. The results suggest that TGF-alpha and TGF-beta may partially be related to the induction of psoriatic epidermal lesions.

Humans↗

PubMed1992

Properties of isolated extrachromosomal nucleoli from Tetrahymena pyriformis.

Extrachromosomal nucleoli were isolated from log phase cells of Tetrahymena pyriformis (amicronucleate strain) in a highly purified state. Nucleoli located at the periphery of the macronucleus were detached from the nucleoplasmic mass of isolated macronuclei with agitation and separated from macronuclei by filtration through a Nuclepore membrane filter (pore size 5 microm). The filtrate constitutes the crude nucleolar preparation, as judged by electron microscopy and DNA analysis. Further purification of the nucleoli was performed by isopycnic centrifugation of the filtrate in a Metrizamide density gradient. After this step, the purity of the nucleoli, as defined by rDNA content and measured by analytical CsCl centrifugation, was almost 100%. Electron microscopy of the purified nucleoli revealed structures that resemble those of an in situ nucleoli. Undegraded 35S pre-rRNA, together with 26S and 17S rRNA, could be isolated from purified nucleoli. In vitro RNA synthetic activity was associated with isolated nucleoli. This activity is insensitive to low and high concentrations of alpha-amanitin, indicating that the form I RNA polymerase is functioning.

Animals↗

PubMed1992

CD7-positive acute myeloid leukemia: further evidence of cellular immaturity.

Among 63 cases of acute myeloid leukemia (AML), 14 were found to express the CD7 antigen, a cell surface marker usually found at an early stage during T lineage differentiation. The CD7-positive AML cases consisted of 5 cases of M1, 3 cases of M2, 3 cases of M4, 1 case of M5, 1 case of M6 and 1 case of M7. Among these 63 cases, the proportion of blast cells expressing the CD34 antigen was examined. The proportion of CD34-stained cells among the CD7-positive AML cases, although varying, was significantly larger than that among the CD7-negative AML cases (P less than 0.05). As the CD34 antigen was expressed on hematopoietic progenitor cells and was considered to reflect an early hematopoietic stage, the high proportion of cells expressing CD34 among the CD7-positive AML cases may support the notion that CD7-positive AML cells are immature.

Adolescent↗

PubMed1992

Circulating CD34+ hematopoietic progenitors in the harvesting peripheral blood stem cells; enhancement by recombinant human granulocyte colony-stimulating factor.

The number of circulating progenitor cells increases during the period of hematopoietic recovery following myeloablative therapy. These progenitor cells were used for autologous transplantation in order to reconstitute hematopoiesis. As an indicator of the circulating progenitor cells, the number of granulocyte-macrophage colony forming units (CFU-GM), which is measured by means of a long-term cell culture, has been widely used. Recently, a cell surface marker, CD34, which can easily be measured by means of flowcytometry, was found to represent immature hematopoietic progenitor cells, which are very close to stem cells. Therefore, the relationship between the number of CD34 positive cells (CD34+ cells) and the number of CFU-GM in the peripheral blood following chemotherapy was studied in 9 patients selected to undergo autotransplantation. The number of peripheral blood CD34+ cells was found to be significantly correlated with that of CFU-GM (r = 0.81). When four out of 9 patients received recombinant human granulocyte-colony stimulating factor (rG-CSF) administration, a significant increase in the release of peripheral blood CD34+ cells as well as peripheral blood CFU-GM was observed (P less than 0.01). Thus, the measurement of CD34+ cells is useful for predicting the number of circulating CFU-GM.

Adolescent↗

PubMed1992

Two types of proliferating cell nuclear antigen (PCNA) complex formation in quiescent normal and xeroderma pigmentosum group A fibroblasts following ultraviolet light (uv) irradiation.

We examined the relationship between the formation of proliferating cell nuclear antigen (PCNA) complex with DNA and nucleotide excision repair in human fibroblasts following ultraviolet light (uv) irradiation. PCNA complex formation was detected by the immunofluorescence method after methanol fixation and nucleotide excision repair activity was detected as the unscheduled DNA synthesis (UDS) by autoradiography labeled with [3H]thymidine. Quiescent normal cells showed a strong punctuated pattern of PCNA staining 5 min to 3 h and UDS 3 h after 10 J/m2 of uv irradiation, but they no longer showed PCNA staining and UDS 24 h after irradiation. In contrast, xeroderma pigmentosum group A (XP-A) cells, which lack UDS activity, did not show PCNA staining up to 30 min after irradiation; however, unexpectedly, they were stained 3 h and even 24 h after irradiation with their staining pattern being different from that in normal cells. Namely, the fluorescence spots in XP-A cells were larger in size and much smaller in number than those in normal cells. When XP-A cells were fused with normal cells with polyethylene glycol treatment, nuclei of XP-A cells showed a PCNA staining pattern similar to that of normal cells at 30 min, which was no longer detected 24 h after irradiation. These results suggest that there exist two types of PCNA complex formation, nucleotide excision repair-related and -unrelated, in human fibroblasts following uv irradiation.

Cell Fusion↗

PubMed1992

Imaging of subunit complexes of thermophilic bacterium H(+)-ATPase with scanning tunneling microscopy.

Using a scanning tunneling microscope (STM), we observed reconstructed subunit complexes of H(+)-ATPase of a thermophilic bacterium. The measurement was carried out in air without conductive coating on the samples deposited on a highly oriented pyrolytic graphite (HOPG). The F1 subunit complex of the H(+)-ATPase, and an H(+)-ATPase whose F0 portion was embedded into liposomes prepared from soybean lecithin were imaged. Overall structural images of the subunit complex F1 were obtained: the structural dimensions of the STM images are in agreement with those deduced from conventional methods such as an transmission electron microscopy (TEM) and small-angle X-ray scattering (SAX) experimentation. Regarding the STM imaging of these samples, we discuss the advantages and disadvantages of the STM over those of conventional methods such as a TEM and SAX.

Cloning, Molecular↗

PubMed1992

Three nonsense mutations responsible for group A xeroderma pigmentosum.

The molecular basis of xeroderma pigmentosum (XP) group A was studied and 3 nonsense mutations of the XP-A complementing gene (XPAC) were identified. One was a nucleotide transition altering the Arg-228 codon (CGA) to a nonsense codon (TGA). This transition creates a new cleavage site for the restriction endonuclease HphI. Of 21 unrelated Japanese XP-A patients examined, 1 (XP39OS) was a homozygote for this mutation and 3 were compound heterozygotes for this mutation and for the splicing mutation of intron 3 reported previously which is the most common mutation in Japanese patients and creates a new cleavage site for the restriction endonuclease AlwNI. The second mutation was a nucleotide transition altering the Arg-207 codon (CGA) to a nonsense codon (TGA). A Palestinian patient (XP12RO) who had severe symptoms of XP was homozygous for this mutation. The third mutation was a nucleotide transversion altering the Tyr-116 codon (TAT) to a nonsense codon (TAA). This transversion creates a new cleavage site for the restriction endonuclease MseI. Of the Japanese patients, 2 with severe clinical symptoms had this mutant allele. One was a compound heterozygote for this mutation and for the splicing mutation, and the other was heterozygous for this mutation and homozygous for the splicing mutation. Although most XP-A patients such as XP12RO have severe skin symptoms and neurological abnormalities of the de Sanctis-Cacchione syndrome, patient XP39OS was an atypical XP-A patient who had mild skin symptoms and minimal neurological abnormalities. Our results suggest that the clinical heterogeneity in XP-A is due to different mutations in the XPAC gene. Moreover, our data indicate that almost all Japanese cases of XP-A are caused by one or more of the 3 mutations, i.e., the splicing mutation of intron 3 and the 2 nonsense mutations of codons 116 and 228. Therefore, by restriction fragment length polymorphism analysis of PCR-amplified DNA sequences using the 3 restriction enzymes described above, rapid and reliable diagnosis of XP-A can be achieved in almost all Japanese subjects including prenatal cases and carriers.

Base Sequence↗

PubMed1992

A mechanistic model for morphogenesis and regeneration of limbs and imaginal discs.

When an amphibian limb, cockroach leg or Drosophila imaginal disc is subjected to a surgical operation, it is capable of regenerating or duplicating certain parts. Although the structure of the regenerated tissue varies depending on the location and mass of the amputated or transplanted part, it can be predicted from a set of formal rules, called the polar coordinate model [French et al., (1976) Science 193, 969-983; Bryant et al., (1981) Science 212, 993-1002]. In the polar coordinate model, it is assumed (and experimentally proven) that the juxtaposition of normally non-adjacent cells stimulates cell proliferation locally, which implies that the underlying mechanism which gives positional values to each cell, is also responsible for the control of cell growth. Because locally activated proliferation alters the shape and size of the developmental field, the question of how to control the cell growth is the central problem in the regeneration of the limbs and imaginal discs. In this paper, I propose a possible underlying mechanism for the 'polar coordinate rules', and show how this mechanistic model explains the experimental results using computer simulation. The proposed mechanism is an extension of Turing's model (1952). In addition to the reaction-diffusion of the molecules, cell proliferation is taken into consideration. With appropriate initial conditions, the computer simulation shows that a small mass of cells grows up to form a mature limb, and that the mature limb is able to respond to surgical operations as predicted by the polar coordinate model.

Amphibians↗

PubMed1992

Clinicopathologic studies on perineural invasion of bile duct carcinoma.

To elucidate the clinical significance of perineural invasion on bile duct cancer, a clinicopathologic study was performed on 70 resected patients with bile duct carcinoma. The overall incidence of perineural invasion in the resected specimen was 81.4%. There seemed to be no correlation between perineural invasion and site, size of the tumor, and lymph node metastasis. A significant correlation was observed, however, between macroscopic type, microscopic type, depth of invasion, and perineural invasion. Perineural invasion index (PNI) was defined as the ratio between the number of nerve fibers invaded by cancer and the total number of nerve fibers with and without cancer invasion. Perineural invasion index was significantly higher at the center compared with the proximal and distal part of the tumor (p less than 0.001). The 5-year survival rate for patients with perineural invasion was significantly lower (p less than 0.05) than that for those without perineural invasion (67% versus 32%).

Adenocarcinoma↗

PubMed1992

Organ culture of psoriatic lesions: appearance of granular layers in vitamin A-free culture media.

Some morphologic changes of the epidermis of psoriatic skin were observed in organ culture in the presence of absence of vitamin A. Normal and uninvolved and involved psoriatic skin areas, punch biopsied in 3-4-mm diameter specimens, were put in serum-free medium containing no vitamin A with or without delipidized fetal calf serum (FCS) and rotation cultured at 60 rpm under an atmosphere consisting of 95% O2 + 5% CO2. The involved psoriatic skin specimens showed well-developed granular layers after 1 d of culture. The values of labeling indices of 3H-thymidine (3H-TdR) incorporated into the epidermal layers of the cultured specimens of the psoriatic skin were nearly constant during culture for as long as 8 d, although the viable epidermal layer gradually became thinner. Addition of tretinoin to the culture caused uninvolved and involved psoriatic skin specimens to become parakeratotic at concentrations as low as about 2.0 x 10(-6) M and 4.0 x 10(-8) M, respectively, suggesting that the involved psoriatic epidermis is much more sensitive, in terms of keratinization, than uninvolved epidermis to the effect of tretinoin.

Culture Media↗