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H Kaneko

Publications and source records attributed to H Kaneko.

At least 235 records · Page 13Linked to original sources
PubMed1997

Cell death during tooth eruption in the rat: surrounding tissues of the crown.

We investigated the occurrence of apoptosis and other types of cell death around the crown during tooth eruption of the rat upper molar. The TdT-mediated-dUTP-biotin nick end labeling (TUNEL) method and transmission electron microscopy (TEM) were employed. Apoptosis was detected by both TUNEL and TEM in part of the reduced enamel epithelium and connective tissue in the resorbing bony crypt of the pre-erupted tooth. In TEM, a large number of cells showed condensed chromatin and membrane-bound small bodies (apoptotic bodies). Macrophages that phagocytosed apoptotic bodies could be detected. Based upon the distance between bone surface and these apoptotic cells, and the characteristics of their organelles, we suggested that the apoptotic cells might be osteocytes, bone-lining cells (osteoblasts), and macrophages. We surmised that the osteoclasts had also died. Cells which contained autophagic vacuoles and autophagosomes, and others whose cytoplasm had dissolved, were also frequently observed. No progressive cell death was found in the oral epithelium or the fibrous connective tissue over the crown. These results suggest that apoptosis gives rise to some cell death during tooth eruption, but that other types of cell death also occur in various cells.

Age Factors↗
PubMed1997

Spatial properties of shear disparity processing.

We investigated whether vertical-shear disparity was extracted from the whole visual field or from a more local area and how global estimates of vertical disparity are derived. We also investigated the role of cyclovergence in processing shear disparity. Random-dot stereoscopic displays in various configurations were presented with horizontal-shear disparity, vertical-shear disparity or same-sign horizontal- and vertical-shear (rotation) disparity. Vertical-shear disparity introduced into only the right half of a 60 deg-wide display produced perceived inclination of the whole display when the center of shear was on the fovea, but did not produce inclination, either of the whole display or of a local area when the centre of shear was in an eccentric retinal position. A display containing dots with vertical-shear disparity mixed with dots with zero-disparity produced one inclined surface. Horizontal-shear disparity always produced inclination confined to the local area of disparity. Rotation disparity produced no inclination when introduced into the whole display, but when introduced with zero-disparity dots. It produced an inclined plane distinct from the plane defined by the zero-disparity dots. These results could be attributed to cyclovergence, which we therefore eliminated in our last experiment. We conclude that the perception of surface inclination is based on the difference between local horizontal-shear disparity and global vertical-shear disparity averaged over the whole visual field.

Depth Perception↗
PubMed1997

Spatial limitation of vertical-size disparity processing.

We investigated the upper limit of horizontal spatial modulation of vertical-size disparity in a textured surface for the perception of depth. In Experiment 1 subjects matched the appearance of a surface with modulated horizontal-size disparity to that of a surface with modulated vertical-size disparity. In Experiment 2 we determined the threshold amplitude of modulation of vertical-size disparity required for the perception of depth as a function of the spatial frequency of disparity modulation. The results indicate that sensations of depth are not elicited by modulations of vertical-size disparity of any amplitude at spatial frequencies higher than about 0.04 c/deg. We conclude that vertical disparities are averaged within about 20 deg-wide areas and suggest that this global measurement is used to scale local horizontal disparities for the perception of surface slant.

Depth Perception↗
PubMed1997

Effects of passive immunization against inhibin on ovulation rate and embryo recovery in holstein heifers.

The effects of acute neutralization of endogenous inhibin on ovulation rate and circulating FSH levels were investigated. Nine or ten days after estrus, 5 heifers were given a single injection of 75 ml iv inhibin antiserum produced in a castrated male goat, while another 5 were given the same amount of a castrated male goat serum. All heifers were given injections of PGF2alpha im at 48 h and 60 h after the serum injection. Those exhibiting an estrus were artificially inseminated with frozen-thawed semen. Seven or eight days after the insemination, ova or embryos were collected using a non-surgical method. Administration of inhibin antiserum resulted in a significant increase in the number of medium-sized follicles compared with the number in the control animals. The number of large follicles in the inhibin-neutralized animals was 4.8 +/- 2.4 (mean +/- SEM; n = 5) on the day of estrus, while there was a single large follicles in the ovaries of control animals. Seven or eight days after estrus, 3 to 16 ova or embryos were recovered from 4 of 5 animals, and 64 % of the total ova/embryos were transferable. Administration of inhibin antiserum produced a significant increase in the concentrations of plasma FSH from 12 to 72 h after the serum injection compared with the levels in the control animals (P < 0.05). After the onset of estrus, preovulatory LH and FSH surges were noted in inhibin-neutralized animals and magnitude of the rise in each hormone was similar to the control animals. The present study demonstrates that a single injection of the inhibin antiserum induces multiple ovulations probably by enhancing FSH secretion, and that recovery of embryos is equal to that observation after an ordinary FSH treatment.

Journal Article↗
PubMed1997

Interphase detection of BCL6/IgH fusion gene in non-Hodgkin lymphoma by fluorescence in situ hybridization.

We characterized a t(3;14)(q27;q32) translocation in nine patients with B-cell, non-Hodgkin lymphoma (B-NHL) by fluorescence in situ hybridization (FISH). Fluorescence in situ hybridization with immunoglobulin heavy chain (IgH) and BCL6 gene probes detected t(3;14) rapidly and accurately, including complex t(3;14) in three patients; one with t(3;12;8;14)(q27;p13;q24.1;q32) and two with t(3;?;14)(q27;?;q32). Among these nine patients, seven escaped from cytogenetic detection by our G-banding analysis. Double-color FISH with IgH (Y6) and BCL6 (cosB5-1) showed fusion of BCL6 and IgH genes on der(3)t(3;14) in all nine patients, suggesting that der(3) may play a critical role in the development of lymphoma carrying complex as well as standard t(3;14) translocations. BCL6/IgH fusion gene was also demonstrated in interphase nuclei at a frequency of 23% to 91.5% over the cut-off value in control studies (9.0 +/- 2.76%). The breakpoints assessed by FISH with two cosmid clones containing BCL6 probes, cosB5-1 and cosB5-2, were within the cluster region in seven patients including one with complex type, but were not evaluated in two patients with t(3;?;14), because of the loss of partner chromosome. Using double-color FISH with these two BCL6-specific probes, none of an additional 32 patients in whom mitotic spreads were available showed 3q27 translocations. Fluorescence in situ hybridization with IgH and BCL6 gene probes is a rapid and sensitive method to detect t(3;14) in routine cytogenetic studies.

Aged↗
PubMed1997

Strategies for harmonic structure discrimination by zebra finches.

We trained zebra finches on a go/no-go operant conditioning procedure to discriminate between two harmonic structures that differed only by the presence or absence of the second harmonic. Test sessions revealed that the birds responded to probe stimuli based on the presence or absence of the second harmonic regardless of the other frequency components. Some of the birds also tended to use the fundamental frequency as a discriminative cue when the number of harmonics was few. These results indicate that birds use multiple strategies for this type of harmonic structure discrimination.

Acoustic Stimulation↗
PubMed1997

Inhibin is involved in the suppression of FSH secretion in the growth phase of the dominant follicle during the early luteal phase in cows.

This study was carried out to examine the involvement of inhibin in the regulation of FSH secretion during the growth phase of the dominant follicle in the early luteal phase of cows. Six cows were given a single i.v. bolus injection of 100 ml inhibin antiserum raised against bovine 32-kDa inhibin in a castrated male goat, and five animals received the same amount of castrated male goat serum (control serum) on Day 5 of the estrous cycle (Day 0 = estrus). All animals in each group experienced a wave of follicular development after ovulation, and the dominant follicle was over 8.5 mm in diameter on Day 5. The corpus luteum was identified for each group on Day 5. Plasma concentrations of estradiol and progesterone gradually increased after ovulation and reached around 3.7 pg/ml and 3.0 ng/ml on Day 5, respectively, suggesting that the dominant follicle and corpus luteum were functional. Administration of inhibin antiserum produced a clear increase (P < 0.001) in plasma FSH within 8 hr compared with that in control animals. Plasma levels of luteizing hormone showed a moderate increase during 40 hr after the injection of antiserum (P = 0.08). A large number of antral follicles (4 mm in diameter) developed after the hypersecretion of FSH, coupled with the rise in plasma estradiol levels. These results clearly demonstrated that inhibin neutralization during the early luteal phase produces hypersecretion of FSH with a coincident stimulation of follicular development, indicating that inhibin is an important factor for the negative regulation of FSH secretion during the early luteal phase when secretion of estradiol and progesterone are normally high.

Analysis of Variance↗
PubMed1997

Preparatory inhibition of cortico-spinal excitability: a transcranial magnetic stimulation study in man.

In order to investigate the preparatory modulations of cortico-spinal excitability, reaction time (RT) methods were combined with transcranial magnetic stimulation (TMS) of the motor cortex. We analyzed the variations in the amplitude of motor potentials evoked in a prime mover (flexor digitorum sublimis) by TMS delivered during the foreperiod of a visual choice RT task. In experiment 1 (n = 10), the TMS was delivered either simultaneously with the warning signal or simultaneously with the response signal in two conditions of foreperiod duration: short (500 ms) and long (2500 ms). The peak amplitude of the motor evoked potentials diminished during the short foreperiod but not during the long foreperiod. Since RT was shorter when the foreperiod lasted 500 ms than when it lasted 2500 ms, this result suggests that the excitability of the cortico-spinal structures is minimal when the subject is optimally ready to react. In experiment 2 (n = 10), the time-course of this decrement was further explored. With this aim, only the short foreperiod was used and the TMS was delivered either 500 ms, 333 ms, 167 ms or 0 ms before the response signal. Cortico-spinal excitability decreased during the first 333 ms and then remained stable until the occurrence of the response signal. In light of previous studies, the present results suggest that the decrement of cortico-spinal excitability during the short foreperiod reflects an adaptative mechanism which increases the sensitivity of the motor structures to the forthcoming voluntary command.

Adult↗
PubMed1997

Tandem duplications of the FLT3 receptor gene are associated with leukemic transformation of myelodysplasia.

We recently reported an internal tandem duplication of the human flt3 receptor gene (FLT3) as a somatic mutation in 17% of acute myelogenous leukemia (AML). The present study revealed the duplication at the juxtamembrane and the first tyrosine kinase domains of FLT3 in seven of 92 (8%) patients with myelodysplastic syndrome (MDS) and AML with trilineage myelodysplasia (AML/TMDS), the diseases which may represent neoplastic changes of pluripotent stem cells. A tandem duplication of exon 11 of FLT3 was harbored by two of 58 (3%) patients with MDS and five of 34 (15%) with overt leukemia, including MDS-derived leukemia, AML/TMDS and therapy-related leukemia. Although the duplicated regions varied within exon 11 in each case, they occurred in-frame, and altered mRNA expressions were demonstrated by reverse-transcription polymerase chain reaction. Two cases of MDS with a FLT3 duplication transformed to overt leukemia within a few months. Longitudinal analyses in two other patients with leukemia revealed that the duplication was a late genetic event during the disease course; one of whom showed two independent duplications of FLT3 at the terminal therapy-resistant phase. Of seven patients with the FLT3 duplication, six had abnormal karyotypes, and four harbored a point mutation of the N-RAS and/or TP53 genes. Patients with FLT3 mutations have poor prognoses. This study uncovered the fact that the accumulation of genetic events, including FLT3 duplication, correlates with leukemic transformation from antecedent myelodysplasia and with subsequent disease progression.

Aged↗
PubMed1997

Congenital leukaemia with a mixed phenotype of megakaryoblasts and erythroblasts: a case report and characterization of the blasts.

We present a congenital leukaemia with a mixed phenotype of megakaryoblasts and erythroblasts. A newborn male with exopthalmus and multiple skin nodules, had bone marrow blasts which expressed CD41b, CD42b, glycophorin-A and haemoglobin, but monocyte or lymphoid markers were negative. The patient achieved a complete remission with chemotherapy. Blasts cultured for a few months expressed erythroid markers but lost the megakaryocytic phenotype, although addition of phorbol ester induced the latter phenotype. Spontaneous colony formation was observed in semi-solid culture and the number of colonies was increased by erythropoietin. Detailed studies further indicated the heterogeneity of congenital leukaemia.

Erythroblasts↗
PubMed1997

Role of tumour necrosis factor-alpha (TNF-alpha) in the induction of HIV-1 gp120-mediated CD4+ T cell anergy.

The HIV-1 envelope glycoprotein (gp 120) is known to induce antigen-specific and non-specific CD4+ T cell anergy. We found that early T cell activation, as indicated by HLA-DP expression in the early G1 (G1A) phase of the cell cycle, and the inhibition of mitogen-mediated IL-2 production induced by gp120, required TNF-alpha produced by gp120-stimulated macrophages. In the presence of an antibody to TNF-alpha, these changes induced by gp120 were inhibited, while recombinant TNF-alpha induced similar abnormalities of CD4+ T cells, even in the absence of gp120. On the other hand, inhibition of the mixed lymphocyte reaction (MLR) in CD4+ T cells by gp120, which may be related to gp120-mediated down-regulation of CD4 expression on T cells and activation of protein tyrosine kinase p56(lck) in CD4+ T cells, was observed even in the absence of macrophage-derived TNF-alpha induced by gp120. These observations indicate that both TNF-alpha-dependent and independent events contribute to gp120-mediated CD4+ T cell anergy, and TNF-alpha appears to play an important role in inducing CD4+ T cell anergy in HIV-1 infection.

CD4-Positive T-Lymphocytes↗
PubMed1997

Reduced expression of the interferon-gamma messenger RNA in IgG2 deficiency.

The specific defect that causes IgG2 deficiency, which is one of the primary immunodeficiencies, is unknown. Recently, it was shown that interferon-gamma (IFN-gamma) induces synthesis of human germline C gamma 2 transcripts. In the authors' previous study and the present one, peripheral blood lymphocytes (PBLs) of all five tested patients with IgG2 deficiency failed to produce enough IFN-gamma when stimulated with phytohaemagglutinin or concanavalin A although they produced a sufficient amount of interleukin-2 (IL-2). The low level of IgG2 production in pokeweed mitogen-stimulated PBLs of four tested patients was improved by the addition of recombinant IFN-gamma. In this study, the amount of IFN-gamma messenger RNA showed various degrees of reduction in all five tested patients. Sequence analysis of the IFN-gamma coding regions and flanking regions revealed neither a point mutation nor a deletion for any of the patients. Thus the results suggest that the reduced expression of IFN-gamma messenger RNA may play an important role in the IgG2 deficiency of these patients.

Antigens, CD↗
PubMed1997

Central vagal activation increases mucus gel thickness and surface cell intracellular pH in rat stomach.

BACKGROUND & AIMS: Central vagal stimulation induced by the thyrotropin-releasing hormone analogue RX 77368 injected intracisternally in urethane-anesthetized rats is gastroprotective. In an in vivo system, the effects of central RX 77368 on discrete components of the rat gastric mucosal barrier were studied to determine if these effects were prostaglandin synthesis dependent. METHODS: Using intravital microscopy, intracellular pH of gastric surface cells, mucus gel thickness, gastric mucosal blood flow, and acid output were measured simultaneously in vivo. RESULTS: Intracisternal RX 77368 significantly increased acid output, gel thickness, and blood flow. Indomethacin enhanced the RX 77368-induced increase in acid output but had no effect on measures of gastric defense during mucosal superfusion with neutral solutions. During acid superfusion, RX 77368 delayed acidification and enhanced recovery of surface cell intracellular pH. These latter effects were reversed partially by indomethacin. Omeprazole abolished RX 77368-induced acid secretion but did not alter its effects on gastric defense mechanisms. CONCLUSIONS: In response to central vagal stimulation with RX 77368, gastric defense mechanisms were enhanced through prostaglandin-dependent and -independent pathways, in contrast to the prostaglandin-independent effects of intravenous pentagastrin. RX 77368-induced enhancements of gastric defense mechanisms did not occur as a result of acid secretion.

Animals↗
PubMed1997

Perceived angular and linear size: the role of binocular disparity and visual surround.

An experiment was conducted to investigate the effects of perspective cue and binocular disparity on perceived angular and linear size. Following the 'angular' and 'linear' instructions, subjects matched the size of two squares, for which the binocular disparity between the centers of the squares and the configuration of the stimulus surrounding the squares were manipulated. Results showed that angular-size matches depended on the retinal-image size and the binocular disparity, and not on the visual-surround stimulus. Linear-size matches, on the other hand, depended on the visual-surround stimulus as well as on the image size and the binocular disparity. The visual-surround stimulus also affects the perceived depth between the test squares. These findings indicate that perceived angular and linear size depend on different processes that use different cues, and suggest that there is a causal relationship between perceived depth and perceived linear size.

Adult↗
PubMed1997

Metabolism of tetramethrin isomers in rat: IV. Tissues responsible for formation of reduced and hydrated metabolites.

1. To identify the sites of formation of the reduced metabolites, 3-hydroxy-cyclohexane-1,2-dicarboximide (3-OH-HPI-1 and -2), 1,2-cyclohexanedicarboxylic acid (TCDA) and 1-hydroxy-1,2-cyclohexanedicarboxylic acid (1-OH-HPA), in rat treated with 14C-labelled (1RS, trans)-tetramethrin, [3,4,5,6-tetrahydrophthalimidomethyl (1RS, trans)-chrysanthemate], bile-duct cannulated animals were orally or intravenously administered 14C-labelled 3,4,5,6-tetrahydrophthalimide (TPI) or 3,4,5,6-tetrahydrophthalic acid (THPA), precursors of these metabolites, and bile, urine and faeces were collected for analysis. 2. 3-OH-HPI-1 and 3-OH-HPI-2, which are cis-form reduced metabolites, and 1-OH-HPA were detected in bile and urine samples of the bile-cannulated rat treated intravenously and orally with 14C-labelled TPI, indicating their formation in tissues or blood. TCDA, a trans-form reduced metabolite, was not detected in bile, urine or faeces of the bile-cannulated rat treated intravenously with 14C-THPA, but was found in the faeces after oral application, indicating formation in the gastrointestinal tract. 3. To clarify whether 1-OH-HPA is produced from THPA via TCDA (hydroxylation via reduction) or by direct addition of H2O to its double bond (hydration), rats were orally administered 14C-labelled TCDA, and metabolites in urine and faeces were analysed. The observed lack of 1-OH-HPA indicated formation by direct addition of H2O to the double-bond of THPA. 4. To specify which tissues form reduced and hydrated metabolites, in vitro metabolism studies were carried out. Reduction to the cis-form was found to take place in blood cells, reduction to the trans-form took place in the gastrointestinal tract contents, and hydration took place in the liver and the intestinal tract contents.

Animals↗
PubMed1997

Cloning and functional analysis of rat cyclin D2 promoter: multiple prolactin-responsive elements.

Structure and function of the promoter region of rat cyclin D2 gene were investigated by cloning, sequence analysis and DNA mobility shift assay using nuclear extracts of prolactin-stimulated Nb2 cells. The results show that the expression of rat cyclin D2 gene is not dependent on the TATA-box but is stimulated by multiple transcription factors induced by prolactin at an immediate-early stage of the cell cycle.

Amino Acid Sequence↗
PubMed1997

Detection of antibodies to a recombinant gag protein derived from human endogenous retrovirus clone 4-1 in autoimmune diseases.

To investigate whether human endogenous retroviruses (HERV) contribute to autoimmune diseases, we prepared a recombinant p30gag protein derived from clone 4-1 of the HERV family, using a baculovirus-vector system. This p30gag protein (CA41B) was approximately 30 kDa, as expected, and reacted with antibodies for p30gag purified from both murine and feline leukemia virus. This result suggested that the antigenic determinant for p30gag was well conserved in CA41B. Analysis of serum antibodies to p30gag in patients with autoimmune diseases was done by Western blotting. CA41B detected anti-p30gag antibodies in 48.3% of systemic lupus erythematosus (SLE) patients, 35.0% of Sjögren's syndrome (SS) patients, and 33.3% of mixed connective tissue disease (MCTD) patients, whereas no anti-p30gag antibodies were found in healthy subjects. This suggested that HERV p30gag or other retroviral p30gag proteins possessing the same antigenic determinant as CA41B may play a role in these diseases. Although detection of antibodies to HERV p30gag in autoimmune diseases is indirect evidence that HERV proteins are involved, this study showed that patients with autoimmune diseases have antibodies to HERV p30gag using a recombinant HERV protein rather than synthetic peptides based on HERV or retroviral proteins of other species.

Animals↗