Biomedical subjects

S Yokota

Publications and source records attributed to S Yokota.

At least 19 recordsLinked to original sources

PubMed1999

In situ determination of proportion of cell types in wood by Fourier transform Raman spectroscopy.

Analysis of the proportion of cell types in native wood is important for understanding the environmental stresses including an increasing atmospheric CO2 concentration on the structure of wood, especially for the management of plantation forests which will reduce our reliance on natural forests. The conventional method for determining the proportion of cell types is a quantitative microscopy, which is one of the image analyzing systems using a light microscope combined with a microcomputer. However, it is a lengthy multistep procedure. We have examined the feasibility of using Fourier transform Raman spectroscopy for rapid determination of proportion of cell types (fiber, ray parenchyma, vessels, and axial parenchyma) in native wood with using wood meals of two Eucalyptus species, including samples of various ages and colors. By the application of second derivative transformation of Raman spectroscopic data and the partial least-squares regression, we have successfully obtained highly significant correlations between microscopically measured and Raman predicted values for all traits except vessels with correlation coefficients of >0.9 and 0.8, respectively, in the calibration and in the prediction. This method is valid for all traits since vessels can be calculated by the rest of three traits, and will help to solve the effect of the environmental issues on trees and the supplement of renewable raw materials.

Cell Lineage↗

PubMed1999

Expression of latent and replicative-infection genes of Epstein-Barr virus in macrophage.

Unlike other herpesviruses, Epstein-Barr virus (EBV) has not yet been shown to infect macrophages. Six macrophage cultures were isolated from normal and affected samples. Nested polymerase chain reaction revealed the existence of the EBV genome in all these macrophages. EBV latent genes expression in all cultures were detected by mRNA in situ hybridization and immunofluorescence staining. Some cultures also expressed EBV replicative-infection proteins, while in other cultures induction of these proteins was demonstrated. These findings are the first to show expression of several latent and replicative-infection genes of EBV in macrophages, indicating that EBV proliferates in macrophages.

Adult↗

PubMed1999

Internal tandem duplication of the FLT3 gene and clinical evaluation in childhood acute myeloid leukemia. The Children's Cancer and Leukemia Study Group, Japan.

We analyzed tandem duplication in the juxtamembrane (JM) domain of the FLT3 (FMS-like tyrosine kinase 3/FLK2, CD135) gene in 94 children with acute myeloid leukemia (AML) and evaluated its correlation with clinical features. Longer polymerase chain reaction (PCR) products were observed in five patients; 1/3 of M0, 119 of M1, 1/39 of M2, 1/9 of M3 and 1/12 of M5. The sequence analyses of abnormal PCR products showed that all the abnormal products were derived from tandem duplications involving the JM domain and that all the lengthened sequences were in-frame as we previously reported. Statistical analyses revealed a significantly lower incidence of the tandem duplication in childhood AML patients than in adult patients (P < 0.05), and significantly shorter disease-free survival in patients with mutant FLT3 than in patients with wild-type FLT3 (P < 0.05). Our results suggest that the tandem duplication in the JM domain of the FLT3 gene is not a frequent phenomenon but might be a factor of poor prognosis in childhood patients with AML.

Acute Disease↗

PubMed1999

[Effectiveness of isoniazid inhalation in patients with endobronchial tuberculosis].

The clinical effectiveness of isoniazid (INH) inhalation was studied retrospectively in 34 patients with endobronchial tuberculosis. Diagnoses of endobronchial tuberculosis and assessments of bronchial stenosis were based on bronchoscopic examinations. We divided the patients into 2 groups: 13 who received systemic chemotherapy for lung tuberculosis only, and 21 who received systemic chemotherapy combined with INH inhalation (200 mg/day). No significant differences distinguished the groups with respect to duration of positive sputum culture or ESR normalization. However, a significant alleviation of bronchial stenosis and earlier reduction of respiratory symptoms were observed in the patients who received systemic chemotherapy with INH inhalation. We concluded that INH inhalation in addition to standard therapy for lung tuberculosis is effective in patients with endobronchial tuberculosis.

Administration, Inhalation↗

PubMed1998

Frequent aberration of FHIT gene expression in acute leukemias.

We analyzed the mRNA expression of the FHIT gene by reverse transcription-PCR (RT-PCR) in 54 cases of acute lymphoblastic leukemia (ALL; 11 cases of T-cell ALL [T-ALL] and 43 cases of non-T-ALL) and 40 cases of acute myeloid leukemia (AML). In 46% of the ALL cases and 55% of the AML cases, FHIT expression was absent or markedly decreased. Only abnormal short bands were detected in 30% of the ALL cases and 5% of the AML cases. Eighteen of 19 abnormal transcripts had the same fusion of exons 2-7, and all lacked the starting codon in exon 5. No obvious normal-sized PCR products were detected in cases exhibiting abnormal transcripts. These findings suggest that the expression of functional FHIT protein was lost in the majority of ALL (76%) and AML (60%) cases. Differential quantitative PCR of exons 3-9 of the FHIT gene and RT-PCR of the PTPRG gene, which is centromeric to the FHIT gene, showed the presence of the target sequences. Fluorescence in situ hybridization analysis using probes covering exons 5 and 8 revealed no difference in the signal patterns between leukemia and normal cells, showing one or two signal doublets in more than 90% of nuclei, and indicated that gross segments of the FHIT gene were not homozygously deleted in these cases. A small number of transcripts with an aberrant fusion between exons 2 and 7 were detected by RT-PCR in the bone marrow cells from four healthy individuals. Granulocytes, lymphocytes, and monocytes in the bone marrow cells of a healthy individual contained transcripts with the same fusion. This unique fusion of exons 2 and 7 might be preferentially seen in either neoplastic or normal hematopoietic cells, regardless of their lineage. The finding that FHIT expression was abolished in the majority of leukemia cases might support the hypothesis that the FHIT gene acts as a tumor suppressor, at least in leukemia.

Acid Anhydride Hydrolases↗

PubMed1998

Tectal projections to the parvicellular reticular formation and the upper cervical spinal cord in the rat, with special reference to axon collateral innervation.

After Phaseolus vulgaris leucoagglutinin injection into the lateral part of the superior colliculus (SC) in the rat, labeled fibers and axon terminals in the lower brainstem were distributed not only in the medial reticular formation but also in the lateral tegmental field including the parvicellular reticular formation (RFp). More caudally, in the upper cervical spinal cord labeled fibers with bouton-like varicosities were distributed mainly in laminae V, VII and VIII, with relatively sparse distribution in lamina IX. These labeled axons were found bilaterally with a clear-cut contralateral dominance. After combined injections of rhodamine-dextranamine, Fluoro-ruby (FR) into the RFp and Fluoro-gold (FG) into the upper cervical spinal cord on the same side, SC neurons labeled with FR were intermingled with those labeled with FG in the lateral part of the SC contralateral to the injection sites. In the stratum griseum intermediale, some of them were double-labeled with both tracers. Our results suggest that SC neurons innervating both the RFp and the cervical spinal cord may be involved in the coordination of head and mouth movements.

Animals↗

PubMed1998

Developmental appearance of oligodendrocytes in the embryonic chick retina.

The axons of the optic nerve layer are known to be myelinated by oligodendrocytes in the chick retina. The development of the retinal oligodendrocytes has been studied immunohistochemically with antibodies against oligodendrocyte lineage: monoclonal antibodies O4 and O1, and an antibody against myelin basic protein. O4 positive (O4+) cells were first detected in the retina on the tenth day of incubation (embryonic day (E)10, stage 36). The labeled cells were located in the optic nerve layer close to the optic fissure. Most were unipolar in shape, extending a leading process with a growth cone toward the periphery of the retina. By E12, unipolar O4+ cells had spread to the middle of the retina. Many O4+ cells close to the optic fissure showed radial arrangement with extension of processes toward the inner limiting membrane. O1+ oligodendrocytes were first observed in the E14 retina positioned just above (interiorly to) retinal ganglion cells. These labeled cells extended fine processes in the optic nerve layer. Limited numbers of myelin basic protein-positive cells were present by E16 and located interiorly to the retinal ganglion cells. In addition to the oligodendrocyte in the optic nerve layer, a limited number of O4+ cells were observed in the inner nuclear layer by E14, and they became O1+ by E18. Furthermore, explant culture experiments showed E10 to be the youngest stage at which the retina contained oligodendrocyte precursors. An intraventricular inj ection of fluorescent dye 1,1',dioctadecyl-3,3,3',3-tetramethylindocarbocyanine perchlorate (DiI) at E6 yielded O4+/DiI+ cells in the retina at E10, which provided direct evidence to support migration of oligodendrocyte precursor into the retina. The present results demonstrated the sequential appearance of the cells of oligodendrocyte lineage and the detailed morphology of the developing oligodendrocytes in the retina. These morphologic features strongly suggested that retinal oligodendrocytes were derived from the optic nerve and spread by migration through the optic nerve layer.

Animals↗

PubMed1998

Significance of chromosomal alterations and mutations of the N-RAS and TP53 genes in relation to leukemogenesis of acute myeloid leukemia.

We examined chromosomes and mutations of the N-RAS and TP53 genes in 73 patients with acute myeloid leukemia (AML). Twenty-six patients showed a reciprocal chromosomal translocation or an inversion, and 34 patients showed only unbalanced aberrations. Balanced aberrations were predominantly detected in the AML patients who did not have myelodysplasia, preceding myelodysplastic syndrome, and a history of chemotherapy or radiation therapy. In contrast, unbalanced aberrations were more frequently seen in the patients with AML with trilineage myelodysplasia, AML transformed from MDS, and therapy-related AML. Twenty-two mutations of the N-RAS and TP53 genes were detected, and these mutations were frequently associated with unbalanced chromosomal aberrations. Furthermore, the spectrum of mutations was suggestive of an exposure to alkylating chemicals.

Acute Disease↗

PubMed1998

Mutational analysis of the N-ras gene in acute lymphoblastic leukemia: a study of 125 Japanese pediatric cases.

A point mutation of the N-ras gene is one of the known genetic alterations identified in patients with acute lymphoblastic leukemia (ALL), but its clinical importance is still controversial. Using polymerase chain reactions, we examined codons 12, 13 and 61 of this gene in 125 Japanese childhood ALL patients (64 common-ALL, 22 pre-B-ALL, 33 T-ALL, 2 B-ALL, 3 undifferentiated ALL, and 1 unclassified ALL) including 9 relapsed patients. An N-ras point mutation was observed in 14 (11%) patients (9 common-ALL, 3 T-ALL, and 2 undifferentiated ALL; 13 patients at diagnosis and 1 at relapse). The patients with undifferentiated ALL harbored an N-ras mutation at a significantly higher rate. However, no correlation was found between the presence of an N-ras mutation and sex, age, or white blood count. There was no significant difference in the event-free survival rate between 13 fresh patients with an N-ras mutation and 103 patients with a wild-type configuration. The N-ras mutation was present in about 10% of childhood ALL cases but it did not have a prognostic impact. The sequence analyses revealed that the majority of the patients (13/14) had an N-ras mutation of a G to A transition. This finding was consistent with previous reports on N-ras mutations in acute leukemias in which the incidence of a G to A mutation was significantly higher in ALL than in myeloid malignancies.

Child↗

PubMed1998

Potentiating action of MKC-242, a selective 5-HT1A receptor agonist, on the photic entrainment of the circadian activity rhythm in hamsters.

Serotonergic projections from the midbrain raphe nuclei to the suprachiasmatic nuclei (SCN) are known to regulate the photic entrainment of circadian clocks. However, it is not known which 5-hydroxytryptamine (5-HT) receptor subtypes are involved in the circadian regulation. In order to verify the role of 5-HT1A receptors, we examined the effects of 5-¿3-[((2S)-1,4-benzodioxan-2-ylmethyl)amino]-propoxy¿-1,3-b enzodioxole HCl (MKC-242), a selective 5-HT1A receptor agonist, on photic entrainment of wheel-running circadian rhythms of hamsters. MKC-242 (3 mg kg(-1), i.p.) significantly accelerated the re-entrainment of wheel-running rhythms to a new 8 h delayed or advanced light-dark cycle. MKC-242 (3 mg kg(-1), i.p.) also potentiated the phase advance of the wheel-running rhythm produced by low (5 lux) or high (60 lux) intensity light pulses. In contrast, 8-hydroxydipropylaminotetralin (8-OH-DPAT)(5 mg kg(-1), i.p.), a well known 5-HT1A/5-HT7 receptor agonist, only suppressed low intensity (5 lux) light-induced phase advances. The potentiating actions of MKC-242 on light pulse-induced phase advances were observed even when injected 20 or 60 min after the light exposure. The potentiating action of MKC-242 was antagonized by WAY100635, a selective 5-HT1A receptor blocker, but not by ritanserin, a 5-HT2/5-HT7 receptor blocker, indicating that MKC-242 is activating 5-HT1A receptors. Light pulse-induced c-fos expression in the SCN and the intergeniculate leaflet (IGL) were unaffected by MKC-242 (3 mg kg(-1), i.p.). HPLC analysis demonstrated that MKC-242 (3 mg kg(-1), i.p.) decreased the 5-HIAA content in the SCN. The present results suggest that presynaptic 5-HT1A receptor activation may be involved in the potentiation of photic entrainment by MKC-242 in hamsters.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1998

Internal tandem duplication of the FLT3 gene is a novel modality of elongation mutation which causes constitutive activation of the product.

An internal tandem duplication (ITD) of the FLT3 gene is found in nearly 20% of acute myeloid leukemia (AML) and 5% of myelodysplastic syndrome cases. Our serial studies on 51 samples with the FLT3 gene mutation indicated that the ITD was frequently (47/51) clustered in the tyrosine-rich stretch from codon 589 to 599 and rarely (3/51) in its downstream region, both of which are located within the juxtamembrane (JM) domain. One remaining sample had an insertion into the JM domain of nucleotides of unknown origin. To elucidate the biological relevance of the ITD or the insertion, we expressed various types of mutant FLT3 in Cos 7 cells. All mutant FLT3 studied were ligand-independently dimerized and their tyrosine residues were phosphorylated. The Y589 of FLT3 was essential for the phosphorylation in the wild FLT3, but a Y589F conversion did not affect the phosphorylation status of the mutant FLT3. These findings suggest that the elongation of the JM domain rather than increase of tyrosine residues causes gain-of-function of FLT3. Thus, ITD is a novel modality of somatic mutation which activates its product. Since the DNA corresponding to codon 593 to 602 potentially forms a palindromic intermediate, we propose that a DNA-replication error might be associated with generating the ITD of the FLT3 gene.

Acute Disease↗

PubMed1998

Recombinant IFN-gamma treatment of a patient with hyperimmunoglobulin E syndrome triggered autoimmune thrombocytopenia.

We report a pediatric patient with hyperimmunoglobulin E syndrome (HIES) treated with recombinant IFN-gamma (rIFN-gamma) for 2 1/4 years who developed autoimmune thrombocytopenia and was positive for serum antiplatelet antibody and antinuclear antibody (ANA). She was then treated with i.v. methylprednisolone pulse therapy followed by oral immunosuppressive drugs. With this therapy, her platelet count increased and was maintained within the normal range for more than a year. We retrospectively examined her sera stored at -40 degrees C for ANA and found that the ANA level was increased from 1:40 to 1:640 with the rIFN-y therapy. Therefore, we believe that, in this case, rIFN-y treatment may have played a crucial role in triggering autoimmune thrombocytopenia. Furthermore, this case demonstrates that caution must be observed in administering rIFN-gamma to genetically predisposed patients.

Antibodies, Antinuclear↗

PubMed1998

Involvement of interleukin-6 in the elevation of plasma fibrinogen levels in lung cancer patients.

BACKGROUND: Involvements of interleukin-6 (IL-6) and fibrinogen in cancer development have been independently studied. However, the association of these molecules in cancer patients remains uncertain. This study was conducted to clarify the association according to the clinicopathological characteristics of lung cancer patients. METHODS: Serum IL-6 levels assayed in 339 patients without pleural effusion were assessed according to clinical stage, histological type of the cancer and levels of fibrin (ogen) degradation products (FDP), and C-reactive protein (CRP). RESULTS: Elevations of serum IL-6 levels more than 4 pg/ml were found in 37.8% of all patients. According to the clinical stage and histological type, the elevations were significantly more frequent in the advanced stage (44.7%), in squamous cell (49.1%) and large cell carcinomas (63.6%). Similarly, the frequency of the elevated cases (> 400 mg/dl) and the mean value of the fibrinogen level were also higher in the advanced stage (54.2%, 455.0 mg/dl) and large cell carcinoma (54.6%, 459.3 mg/dl), respectively. The elevations of fibrinogen, FDP and CRP levels were found to be related to those of the IL-6 level. CONCLUSION: In lung cancer, serum IL-6 elevations are particularly frequent in the advanced stages of patients with squamous cell and large cell carcinoma, which are associated with the elevated levels of fibrinogen, suggesting a possibility that IL-6 was involved not only directly, but also indirectly, through regulating plasma fibrinogen with promotion of cancer development in vivo.

Adenocarcinoma↗

PubMed1998

Identification and characterization of a cytotoxic T cell epitope of hepatitis C virus presented by HLA-B*3501 in acute hepatitis.

In order to clarify the role of cytotoxic T lymphocytes (CTL) in hepatitis C virus (HCV) infection, an HLA-B35-restricted cytotoxic T cell epitope of HCV was identified using a strategy called reverse immunogenetics. Twenty-eight of 53 HCV peptides carrying two anchor residues were selected as HLA-B*3501 binding peptides. These peptides were used to induce the specific cytotoxic T cells in peripheral blood lymphocytes from a patient with acute hepatitis C. Six HLA-B*3501 binding peptides induced the peptide-specific CTL. One (HPNIEEVAL) of five peptides was confirmed as the epitope by the specific T cell clones. A sequence identical to the epitope was detected in isolates of the virus from the patient and a strong CTL response to this epitope was observed in the acute phase of hepatitis C but not in the recovery phase. The specific CTL for this epitope were not detected in peripheral blood lymphocytes from patients with chronic hepatitis C. Together these results suggest that the CTL specific for this epitope have an important role in the elimination of the virus in the patient.

Acute Disease↗

PubMed1998

Utilization of proteinase K-treated cells as lipopolysaccharide antigens for the serodiagnosis of Helicobacter pylori infections.

We have evaluated the use of proteinase K (PK)-treated cells isolated from Helicobacter pylori as lipopolysaccharide (LPS) antigens in an immunoblot assay and an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of H. pylori infection. The sera from patients with chronic gastritis, gastric ulcer, duodenal ulcer or gastric cancer, and from healthy adults with or without H. pylori infection were assayed with three commercial serodiagnostic kits (HM-CAP, Helico-G, and G.A.P. II) and novel methods relying on the use of PK-treated cells. The PK-treated cells used in these assays were selected on the basis of their possibility to possess a common epitope in the O-polysaccharides of H. pylori, which is known to be highly immunogenic in humans. Of the sera from these patients, 71-94% were positive with the commercial kits, 97% with immunoblot assay, and 90% with ELISA. On the other hand, of the healthy adults infected with H. pylori, 72-97% were positive with the commercial kits, 86% with immunoblot assay, and 72% with ELISA. PK-treated cells that did not contain the common epitope were unsuitable as an antigen for immunoblot assay or ELISA. Furthermore, the reactivity of these sera reacted specifically with H. pylori PK-treated cells but not with LPSs from other gram-negative bacteria, such as Campylobacter, Proteus, Bordetella, and Salmonella. These results demonstrate that the serological assays relying on the use of H. pylori PK-treated cells possessing a highly antigenic epitope are potentially useful as a serodiagnostic test for H. pylori infection.

Adult↗

PubMed1998

Haematopoietic action of flt3 ligand on cord blood-derived CD34-positive cells expressing different levels of flt3 or c-kit tyrosine kinase receptor: comparison with stem cell factor.

We compared the effect of human flt3 ligand (FL) and stem cell factor (SCF) on cord blood (CB)-derived CD34+ cells expressing different levels of flt3 or c-kit tyrosine kinase (TK) receptor in clonal cell culture. The c-kit receptor was expressed by 58.5+/-16.7% of CB CD34+ cells (n=19), in which c-kit(high), c-kit(low) and c-kit cell populations could be identified. In contrast, the flt3 receptor (FR) was weakly expressed on 58.6+/-8.3% (n=9) of CB CD34+ cells. FL+erythropoietin (Epo) failed to support erythroid burst (BFU-E) formation by any subpopulation of CD34+ cells. However, SCF + Epo supported BFU-E and erythrocyte-containing mixed (CFU-mix) colony formation from all subpopulations. Interestingly, FL markedly augmented CFU-mix colony formation supported by interleukin (IL)-3 + Epo when CD34+c-kit(low) or CD34+FR+ cells were used as the target. On the other hand, SCF significantly enhanced CFU-mix colony formation supported by IL-3 + Epo when CD34+c-kit(high) or low and CD34+FR+ cells were used. The replating potential of CFU-mix supported by IL-3 + Epo+ FL was greater when CD34+c-kit(low) or CD34+FR+ cells were used. When the CD34+c-kit(low) cells were used, the number of lineages expressed in secondary cultures of CFU-mix colonies derived from primary cultures containing IL-3 + Epo + FL or SCF was significantly larger than when the primary cultures contained IL-3 + Epo. Furthermore, the number of long-term culture-initiating cells found in CD34+FR+ cells was larger than that in FR cells. CB-derived CD34+c-kit(low) cells represent a less mature population than c-kit(high) cells, as reported previously. Therefore, these results indicate that both FL and SCF can act on primitive multipotential progenitors. However, it is still uncertain whether CB-derived CD34+FR+ cells are less mature than CD34+FR- cells.

Antigens, CD34↗

PubMed1998

Epidemiological study of a food-borne outbreak of enterotoxigenic Escherichia coli O25:NM by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA analysis.

This study investigated the applicability of molecular epidemiological techniques to the identification of the causal agent of an outbreak of diarrhea caused by ingestion of food contaminated with enterotoxigenic Escherichia coli (ETEC). The outbreak occurred at four elementary schools in July 1996 and affected more than 800 people. Illness was most strongly associated with eating tuna paste (relative risk, 1.79; 95% confidence interval = 1.16 to 2.79; P = 0.0001). To evaluate the epidemiological characteristics of the pathogen, the DNAs from numerous isolated ETEC strains were subjected to randomly amplified polymorphic DNA analysis, pulsed-field gel electrophoresis of nuclease S1-treated plasmid DNA, and analysis of genomic DNA restriction fragment length polymorphisms. All ETEC isolates were of the O25:NM (nonmotile) serotype, which carries a heat-stable enterotoxin Ib gene. Genotypic analysis demonstrated that the strains isolated from the patients at all four schools were identical. The isolates of ETEC O25:NM obtained from the tuna paste that had been served for lunch at these schools were genetically indistinguishable from those isolated from the patients. Results suggest that this outbreak was food borne. The molecular biology-based epidemiological techniques used in this study were useful in characterizing the causal agent in this food-borne epidemic.

Animals↗

PubMed1998

Rare alteration of genomic structure or expression of the DPC4 gene in myelogenous leukemias.

We examined homozygous deletion, point mutation and expression of DPC4 gene, a recently isolated candidate pancreatic tumor suppressor gene, in 53 patients with myelogenous leukemias and 5 cell lines. The patients consisted of 34 cases of chronic myelogenous leukemia including 22 in the chronic phase, 3 in the accelerated phase, and 9 in blastic crisis, and 19 with acute myelogenous leukemia including 9 at the initial presentation and 10 at relapse. Polymerase chain reaction (PCR)-based deletion analysis for DPC4 exon 8 and PCR-single strand conformation polymorphism study for the entire coding region were carried out. Homozygous deletion or subtle mutation was not detected in any of the samples examined. However, 3 patients with various clinical phases showed a decrease of DPC4 expression. These results suggest that DPC4 alteration is not a crucial event in the development or the progression of myelogenous leukemias.

DNA-Binding Proteins↗