Biomedical subjects

H Honda

Publications and source records attributed to H Honda.

At least 199 records · Page 11Linked to original sources

PubMed1997

Interaction of extraretinal eye position signals in a double-step saccade task: psychophysical estimation.

The time course of extraretinal eye position signals (EEPSs) for visually guided saccades made successively with a short intersaccadic interval was estimated on the basis of perceptual errors in localizing a visual target flashed between the two saccades. The EEPSs for the first and the second saccades were shown to interact in a specific way when the intersaccadic interval was short. The pattern of interaction depended on the direction of the second saccade. It is suggested that when the second saccade was made in the opposite direction to the first saccade, the EEPS for the first saccade was interrupted before its completion in preparation for the onset of the second saccade. When the two saccades were made in the same direction, the EEPS for the first saccade developed more quickly than in a single-saccade condition. The results are discussed in relation to the findings of recent neurophysiological studies.

Humans↗

PubMed1997

The effect of applied mechanical vibration on two different phases of rat papillary muscle relaxation.

Applying external mechanical vibration during the relaxation phase of rat papillary muscle decreases the duration of the first part of the relaxation phase. To elucidate the basic mechanism responsible for this shortening of the relaxation period, we applied a controlled vibration to isolated twitching rat papillary muscles during various phases in the relaxation of a twitch. The first part of the relaxation phase was accelerated when length perturbations were applied in the first part of the relaxation of a twitch, dependent on both amplitude and frequency of the perturbation. When vibrations were applied in the first half of the relaxation, the second phase of relaxation was slightly slower (about 20%), but when no vibrations were applied in the first phase, relaxation could be accelerated by applying vibration in the latter half of the relaxation phase. Thus, in the latter half of relaxation, the acceleration of relaxation depended upon perturbation events earlier during that twitch. This study indicates that vibration-induced acceleration of relaxation is due (at least in part) to an apparent increase in detachment rate of attached cross-bridges from the thin filament without substantial reattachment.

Animals↗

PubMed1997

Aggravation of murine experimental allergic encephalomyelitis by administration of T-cell receptor gammadelta-specific antibody.

Experimental allergic encephalomyelitis (EAE) is thought to be dominantly mediated by Ag-specific CD4+ MHC class II-restricted T-cells. Recent reports demonstrated accumulation of gammadelta T-cells in active multiple sclerosis (MS) plaque and infiltration into brains with EAE. However, the role of gammadelta T-cells in pathogenesis of EAE remains unknown. In the present study we have examined EAE mice administered T-cell receptor (TCR) gammadelta-specific mAb (UC7-13D5) to elucidate the potential role of gammadelta T-cells in the pathogenesis of EAE. MAb treatment led to transient depleting gammadelta T-cells in vivo. MAb-treated EAE mice showed aggravation and disease recurrence and also increased Ag-specific proliferative responses. Semiquantitative PCR analysis demonstrated an increased level of IFN-gamma mRNA expression in splenocytes from mAb-treated EAE mice during the induction and pre-relapse phase, however, aggravation and disease recurrence have not been suggested to be directly mediated by IFN-gamma in the present study. Our results imply that gammadelta T-cells play a preventing role in the recurrence of EAE.

Animals↗

PubMed1997

A difference in responsiveness of isolated hepatic artery, aorta, portal vein and vena cava of pig to flavin adenine dinucleotide including liver extract.

1. Tension of isolated hepatic artery, aorta, portal vein and vena cava of pigs was measured isometrically to study the mode of action of flavin adenine dinucleotide, including liver extract (FADLE). 2. FADLE showed concentration-dependent relaxation of norepinephrine contraction in the hepatic artery, but FADLE had little influence on the aorta, portal vein and vena cava contracted by norepinephrine (NE). 3. In Ca(2+)-free solution, FADLE-induced relaxation in both the hepatic artery and aorta contracted by NE was significantly reduced, and its reduction was greater in the hepatic artery than in the aorta. Furthermore, extracellular Ca2+ dependence of norepinephrine-induced contraction was much larger in the hepatic artery than in the aorta. 4. Results suggest that FADLE shows regional variations in vasorelaxation through the alteration of Ca2+ movement by the cell, and that this may reflect one of the mechanisms in its ability to increase blood flow in hepatic tissue.

Animals↗

PubMed1997

Regulation of interneuron function in the C. elegans thermoregulatory pathway by the ttx-3 LIM homeobox gene.

Neural pathways, which couple temperature-sensing neurons to motor and autonomic outputs, allow animals to navigate away from and adjust metabolism rates in response to the temperature extremes often encountered. ttx-3 is required for the specification of the AIY interneuron in the C. elegans neural pathway that mediates thermoregulation. ttx-3 null mutant animals exhibit the same thermotactic behavioral defect as that seen with laser ablation of AIY in wild type, suggesting that AIY does not signal in this mutant. ttx-3 encodes a LIM homeodomain protein. A ttx-3-GFP fusion gene is expressed specifically in the adult AIY interneuron pair, which connects to thermosensory neurons. In ttx-3 mutant animals, the AIY interneuron is generated but exhibits patterns of abnormal axonal outgrowth. Thus, the TTX-3 LIM homeodomain protein is likely to regulate the expression of target genes required late in AIY differentiation for the function of this interneuron in the thermoregulatory pathway. The ttx-3-dependent thermosensory pathway also couples to the temperature-modulated dauer neuroendocrine signaling pathway, showing that ttx-3 specifies AIY thermosensory information processing of both motor and autonomic outputs.

Amino Acid Sequence↗

PubMed1997

Inhibitory effect of a new steroidal saponin, OSW-1, on ovarian functions in rats.

1. This study was undertaken to determine the effects of OSW-1 (3 beta, 16 beta, 17 alpha-trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-beta-D-xylopyranosyl)- (1-->3)-(2-O-acetyl-alpha-L-arabinopyranoside)) on the pituitary-ovarian system and the functions of aortic smooth muscle. 2. A single s.c. injection of OSW-1 (9 micrograms kg-1) on the morning of pro-oestrus inhibited the occurrence of the expected next pro-oestrus, whereas administration of OSW-1 at a dose of 4.5 micrograms kg-1 did not affect the oestrous cycle. OSW-1 treatment on the day of dioestrus-1 did not affect the oestrous cycle. 3. At doses of 4.5 and 9 micrograms kg-1 OSW-1, the serum oestradiol (E2) levels at the expected next pro-oestrus were significantly lower than in control (pro-oestrus). The serum luteinizing hormone (LH) levels 4 days after 9 micrograms kg-1 OSW-1 treatment were also markedly lower than those of control. OSW-1 (4.5 micrograms kg-1) did not affect the levels of inhibin, progesterone and gonadotrophins on the same day. 4. OSW-1 did not inhibit the preovulatory LH surge which occurs on the afternoon of pro-oestrus day. 5. The expression of mRNA coding for the cholesterol side chain cleavage cytochrome P-450 (p450scc), an ovarian steroidal limiting enzyme, was suppressed at 24 and 96 h after OSW-1 treatment. 6. Administration of OSW-1 (9 micrograms kg-1) tended to reduce the relaxation of isolated thoracic aorta ring preparations induced by acetylcholine, while there was no difference in the relaxation induced by sodium nitroprusside. 7. Our results show that OSW-1 inhibits ovarian E2 secretion and that the decrease in E2 secretion may contribute to its effects on the oestrous cycle and the sensitivity of the thoracic aorta to relaxation. The decrease in the levels of ovarian steroids induced by OSW-1 may be due to its direct inhibitory action on the gene expression of the steroidal enzyme and on the proliferation of granulosa cells in the ovary.

Animals↗

PubMed1997

Overexpressed Bcl-x(L) prevents bacterial superantigen-induced apoptosis of thymocytes in vitro.

bcl-x, a homologous gene of bcl-2, has an anti-apoptotic function and appears to play a critical role in the development of lymphoid systems. To investigate the effect of overexpressed Bcl-x(L) on the development of T lymphocytes, we established two lines of transgenic mice by using Emu-chicken bcl-x(L) (cbcl-x(L)) transgene, where the cBcl-x(L) protein was expressed mainly in lymphoid cells. Although thymocytes and splenocytes from cbcl-x(L) transgenic mice are resistant to apoptosis in vitro, clonal deletion of thymocytes, recognizing endogenous self-superantigens in the thymus, still normally proceeded and no self-reactive T cells were found in the spleen of the transgenic mice. To dissect clonal deletion, we utilized two in vitro models, thymocytes/antigen presenting cells co-culture system and fetal thymus organ culture system. In both, bacterial superantigen staphylococcus aureus enterotoxin B (SEB) induces apoptosis of T cells with Vbeta8+ T cell receptor (TCR) reacting to SEB, which mimics clonal deletion of self-reactive thymocytes in vivo. SEB-induced depletion of Vbeta8+ T cells from thymocytes when taken from the transgenic mice was effectively inhibited. The data might raise the possibility that cell death process involved in clonal deletion in the thymus is a form of apoptosis inhibited by Bcl-x(L).

Journal Article↗

PubMed1997

Characterization of the mouse prostaglandin F receptor gene: a transgenic mouse study of a regulatory region that controls its expression in the stomach and kidney but not in the ovary.

BACKGROUND: The actions of prostaglandin F2alpha are mediated by a cell-surface receptor (FP), but little is known about the regulation of FP gene expression. To clarify the mechanisms underlying tissue specific transcription of the mouse FP gene, we isolated and characterized mouse genomic DNA clones encoding FP. RESULTS: Structural analysis revealed that the mouse FP gene is composed of three exons and two introns, and spans more than 11 kilobases. By primer extension and PCR analyses, the major transcription start site was identified as a cytosine nucleotide, but additional sites of transcription initiation were found in the ovary. There was no apparent difference in the FP gene transcription initiation site between the ovary, kidney and stomach. Sequence analysis of the putative promoter region showed only two potential SP-1 binding sites, but no other typical well-known consensus sequences. We generated transgenic mice with the potential promoter region of the FP gene connected to the lacZ reporter gene. Northern blot analysis showed that the pattern of expression of the transgene corresponded to that of FP expression, except in the ovary. Upon analysis by in situ hybridization, the lacZ gene transcripts were found to be expressed in the fundic glands in the stomach, and the cortical tubules in the kidney, in which endogenous FP transcripts were also expressed. On the contrary, expression of lacZ transcripts was not detected in the corpora lutea, where the highest expression of FP mRNA was observed. CONCLUSIONS: These studies suggest that a separate control mechanism exists for FP expression in the ovary, distinct from the expression in the stomach and kidney.

Amino Acid Sequence↗

PubMed1997

Formation of the branching pattern of blood vessels in the wall of the avian yolk sac studied by a computer simulation.

The present study was performed to provide data to support the notion previously believed but not proved experimentally or theoretically, that blood vessels are formed by the selection of capillaries in the network. In an attempt to understand the mechanism of formation of blood vessel branching structures, the transformation of a capillary network to a branching system in the wall of quail yolk sac was successively recorded by a series of photographs, and a computer simulation was carried out for the process of in vivo vascularization based on the photographs. The simulation demonstrated that a positive feedback system participated in the formation of a branching structure. That is, vessels which had been much used were enlarged, whereas less used vessels were reduced in their size and finally extinguished. The enlarged vessels became major components of the branching system. As the body of an embryo grew, it was observed that polygonal capillary networks enlarged, which led each polygon of the network to divide into a few finer polygons. Then, some of the capillary vessels were again selected and formed a branching system. This process repeated during the body growth, indicating that the vascular system developed adaptively to the body growth. A region where the growth was fast, received much blood flow and produced finer networks of capillaries. Thus, it was experimentally demonstrated for the first time that capillaries in the network are successively selected by a positive feedback mechanism and form blood vessels.

Animals↗

PubMed1997

Regulated crosslinked actin filaments and the decoupling between their ATPase activity and sliding motility.

Troponin-tropomyosin complex from skeletal muscles was observed to regulate sliding movement of actin filaments on myosin molecules in a manner independent of their ATPase activity. When actin molecules were crosslinked with DSS (disuccinimidyl suberate), the myosin ATPase activity in the presence of the modified actin filaments complexed with both troponin and tropomyosin was only 10% less than that in the case of unmodified actin, and the ATPase activation was independent of calcium ions. In contrast, the sliding velocity of the modified actin filaments on myosin molecules decreased to zero below pCa 6.5. The present results indicate that troponin-tropomyosin complex regulates contractile movement of actomyosin systems through direct alternation of a mechanochemical property of the thin filaments, not through a decrease in the ATPase activity of the myosin molecules.

Actin Cytoskeleton↗

PubMed1997

Small hepatocellular carcinoma on magnetic resonance imaging. Relation of signal intensity to angiographic and clinicopathologic findings.

RATIONALE AND OBJECTIVES: The authors discuss the clinicopathologic features and angiographic vascularity of various signal intensity patterns on magnetic resonance (MR) imaging of small hepatocellular carcinomas (HCCs). METHODS: Magnetic resonance images of 88 resected HCCs (< or = 3 cm) were obtained using T1- and T2-weighted spin-echo images and T1-weighted images after gadolinium (Gd)-DTPA administration. Images were compared with angiographic and histopathologic findings. RESULTS: Forty HCCs (45%) were depicted on T1-weighted images, 51 (58%) on T2-weighted images, and 41 (49%) on T1-weighted images after Gd-DTPA administration. Overall, 64 (76%) were found on at least one image. On T1-weighted images, hyperintense HCCs histologically showed fatty metamorphosis and portal tracts within the tumor. On T2-weighted images, HCC hyperintensity correlated with expansive growth, peliotic change, and hypervascularity. By contrast, HCCs that were undetected or hypointense on T2-weighted images were well differentiated with replacing growth and portal tracts. On T1-weighted images after Gd-DTPA, hyperintense HCCs had peliotic change; undetected HCCs were well differentiated and hypovascular. CONCLUSIONS: Histologic grade, vascularity, portal tracts and peliotic change correlate with MR signal intensity. For hyperintense HCCs on T1-weighted images and hypo- or isointense HCCs on T2-weighted images, treatment methods must be assigned with the consideration that HCCs may be receiving transsinusoidal and portal blood supplies.

Adult↗

PubMed1997

Epidermal remodeling in psoriasis (II): a quantitative analysis of the epidermal architecture.

Hyperproliferative psoriatic epidermis was quantitatively analyzed using a geometric model of viable epidermis. Our model was based on hexagonally arranged cylindrical papillae, which allowed the determination of the total volume of the viable epidermis and the total area of the interface with the proliferative compartment based on several parameters, such as papillary height, papillary width, and distance between neighboring papillae. The analysis assumed that the total number of viable epidermal cells paralleled the proliferative compartment in a steady state of cell flow, so a quantitative relation could be made between both volume and interface of the viable epidermis. Multiple parameters of the psoriatic epidermal architecture were measured, and variations within psoriasis were predicted by the model. The results predicted were remarkably close to the observed values. The geometric model also indicated that psoriatic epidermis could be subdivided into two distinct types, with and without a granular layer; the latter having a shorter turnover time. This is consistent with the notion that the typical psoriatic epidermis (without the granular layer) represents the expanding hyperproliferative phase, whereas the psoriatic epidermis with a granular layer represents stationary or resolving states. The model of hexagonally arranged cylindrical papillae suggested that the architecture of the psoriatic epidermis is constructed by a simple mechanism, whereby the psoriatic angulated rete-papilla pattern was produced by a two-dimensional increase in the proliferative compartment and a three-dimensional increase in the total volume of the viable epidermis.

Epidermis↗

PubMed1997

Intracellular hyperthermia for cancer using magnetite cationic liposomes: ex vivo study.

Heating properties of magnetite cationic liposomes (MCL) were investigated in ex vivo experiments using implanted cell pellets. The cell pellets, which consisted of rat glioma T9 cells into which MCL had been incorporated in a petri dish, were implanted subcutaneously in the left femoral region of female F344 rats. The rats were placed in a magnetic field generating coil and irradiated with an alternating magnetic field (384 Oe, 118 kHz) for 60 min. The cell pellets were heated to over 43 degrees C by MCL in the magnetic field, but other body parts of the rats were not heated. After 3 cycles of magnetic heating, all glioma cells were killed and no tumor take was observed.

Animals↗

PubMed1997

A phenotypically normal liveborn male after prenatal diagnosis of trisomy 20 mosaicism.

We report on a case of prenatally diagnosed trisomy 20 mosaicism. Conventional cytogenetic analysis and fluorescence in situ hybridization (FISH) using a chromosome 20 specific probe were performed on the lymphocytes and extra-embryonic tissues after birth. All of them revealed normal karyotypes. The baby is developing normally at the age of 2 years.

Adult↗

PubMed1997

[Virological studies on HTLV-1 carrier pregnant women].

Vertical transmission of HTLV-1 (human T-cell leukemia virus type 1) from HTLV-1 carrier mothers to their newborns has been reported with transmission rates, ranging from 6% to 78%. This study was undertaken to identify the high risk group of vertical transmission by detecting viral antigen in cultured lymphocytes and provirus obtained from carrier mothers. Subjects of this study were 70 HTLV-1 carrier mothers who attended the department of obstetrics and gynecology of hospital located in the Kanto area (ATL non endemic area). HTLV-1 antigen was detected in 40 out of 55 (72.7%) in peripheral blood lymphocytes of carrier mothers. HTLV-1 antigen was detected in 2 out of 40 (5.0%) in cord blood lymphocytes of infants born of carrier mothers. These two infants were born from carrier mothers with positive antigen detection study. It seems that carrier mothers whose peripheral lymphocytes are positive for antigen expression by culture are a high risk group for vertical transmission.

Carrier State↗

PubMed1997

Requirements for localization of p130cas to focal adhesions.

p130cas (Cas) is an adapter protein that has an SH3 domain followed by multiple SH2 binding motifs in the substrate domain. It also contains a tyrosine residue and a proline-rich sequence near the C terminus, which are the binding sites for the SH2 and SH3 domains of Src kinase, respectively. Cas was originally identified as a major tyrosine-phosphorylated protein in v-Crk- and v-Src-transformed cells. Subsequently, Cas was shown to be inducibly tyrosine phosphorylated upon integrin stimulation; it is therefore regarded as one of the focal adhesion proteins. Using an immunofluorescence study, we examined the subcellular localization of Cas and determined the regions required for its localization to focal adhesions. In nontransformed cells, Cas was localized predominantly to the cytoplasm and partially to focal adhesions. However, in 527F-c-Src-transformed cells, Cas was localized mainly to podosomes, where the focal adhesion proteins are assembled. The localization of Cas to focal adhesions was also observed in cells expressing the kinase-negative 527F/295M-c-Src. A series of analyses with deletion mutants expressed in various cells revealed that the SH3 domain of Cas is necessary for its localization to focal adhesions in nontransformed cells while both the SH3 domain and the C-terminal Src binding domain of Cas are required in 527F-c-Src-transformed cells and fibronectin-stimulated cells. In addition, the localization of Cas to focal adhesions was abolished in Src-negative cells. These results demonstrate that the SH3 domain of Cas and the association of Cas with Src kinase play a pivotal role in the localization of Cas to focal adhesions.

3T3 Cells↗

PubMed1997

Significance of liver size in hepatic surgery.

The purpose of this study was to evaluate the significance of liver volumetry as a parameter for hepatic functional reserve in cirrhotic patients with hepatocellular carcinoma. Liver volume was calculated from preoperative computed tomograms of 44 cirrhotic patients who underwent elective hepatic resections for hepatocellular carcinoma. The liver volume per body weight of non-alcoholic cirrhotics was significantly smaller than that of alcoholic cirrhotics (20.9 vs. 26.7 cc/kg; p = 0.03). The values for alcoholic cirrhotics was comparable with normal values. The liver volume per body weight of the cirrhotic patients demonstrated correlation with the preoperative serum albumin (p < 0.01) and indocyanine green clearance (p = 0.02). We conclude that the determination of hepatic atrophy by volumetry can serve as a parameter for the assessment of hepatic reserve but not as a predictor of postoperative complications in elective liver surgery for cirrhotic patients.

Atrophy↗

PubMed1997

Influence of OSW-1 [3 beta,16 beta,17 alpha-trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1--> 3)-(2-O-acetyl-alpha-L-arabinopyranoside)], a steroidal saponin, on endothelium dependent relaxation caused by acetylcholine in rat aorta.

The tension of isolated ring preparation of the aorta from rats was measured isometrically to study the influence of OSW-1 [3 beta,16 beta,17 alpha-trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1 right arrow 3)-(2-O-acetyl-alpha-L-arabinopyranoside)], a steroidal saponin, on the endothelium dependent and independent relaxation caused by acetylcholin (ACh) and sodium nitroprusside (SNP), respectively. OSW-1 (10(-7) M), which has more than 100 times higher concentration for anti-tumor activity, had no influence on either the endothelium dependent or independent relaxation. OSW-1 (10(-6) M, 0.9 microgram/ml) slightly reduced the endothelium dependent relaxation caused by ACh but did not affect the SNP-induced relaxation. In contrast to OSW-1, 1 mg/ml of saponin significantly suppressed the ACh-induced relaxation and shifted the dose-relaxation curve for SNP to the right. OSW-1 (10(-7) and 10(-6) M) did not affect the norepinephrine-induced contraction but 1 mg/ml of saponin significantly attenuated it. The results suggest that though the higher concentration of OSW-1 shows weaker influence on the endothelium function compared with saponin, OSW-1 at an anti-tumor dose has no influence on either endothelium or smooth muscle function.

Acetylcholine↗