Search PubMed⌕ Search

Biomedical subjects

H Yamane

Publications and source records attributed to H Yamane.

At least 55 records · Page 3Linked to original sources
PubMed1998

IL-12 receptor (IL-12R) expression and accumulation of IL-12R beta 1 and IL-12R beta 2 mRNAs in CD4+ T cells by costimulation with B7-2 molecules.

IL-12 is a crucial cytokine for the determination of a Th1/Th2 balance. It is important, therefore, to elucidate the mechanisms of IL-12R expression on Th cells. In this report, we present evidence to show that B7-2 costimulation plays a pivotal role in the expression of IL-12R on Th cells. A Th1 clone expressed a low density of IL-12R in a resting condition, the expression was enhanced by stimulation with specific Ag on splenic adherent cells and the enhancement was inhibited by anti-B7-2 or CTLA-4-Ig. When stimulated with anti-CD3 plus B7-2-transfected Chinese hamster ovary (CHO) cells, the clone strongly expressed IL-12R, although anti-CD3 by itself only weakly enhanced the expression. We obtained results that were similar to those in the Th1 clone in CD4+ CD45RB(low) memory T cells. In CD4+ CD44(low) naive T cells, costimulation with B7-2-CHO was found to play a more important role in IL-12R expression. The accumulation of both IL-12R beta 1 and -beta 2 chain mRNAs was detected in naive T cells only when they were costimulated with anti-CD3 and B7-2-CHO, but beta 2 mRNA was not expressed upon anti-CD3 stimulation alone. On the other hand, both Th1 clones and memory T cells expressed low amounts of these mRNA without any stimulation, and the expression was weakly enhanced by anti-CD3 stimulation alone. For the maximum expression of these mRNAs, however, these cells also required costimulation with anti-CD3 and B7-2-CHO.

Animals↗
PubMed1998

Purification and activation of recombinant p38 isoforms alpha, beta, gamma, and delta.

p38 is a proline-directed serine/threonine kinase that is activated by inflammatory cytokines and cellular stress. At present, four isoforms of p38 have been identified and termed alpha, beta, gamma, and delta. We expressed each p38 homolog in Escherichia coli and purified the recombinant isoforms. p38alpha and C-terminal Flag-tagged p38beta were purified by Q-Sepharose fast flow, hydroxyapatite, and Q-Sepharose high-performance chromatography. His-tagged p38gamma was purified using Ni2+-NTA resin followed by Mono Q chromatography. Glutathione S-transferase-Flag p38delta was purified using M2 affinity agarose and gel-filtration chromatography. Upstream activators of p38, constitutively active (ca) MKK3 and MKK6, were also cloned, purified, and used to activate each p38 isoform. p38 alpha, gamma, and delta were phosphorylated by both MKK6 and caMKK3. p38beta was phosphorylated only by MKK6. Mass spectrometry analysis and kinase assays showed that MKK6 was the superior reagent for phosphorylating and activating all p38 isoforms.

Activating Transcription Factor 2↗
PubMed1998

Apoptosis of guinea pig cochlear hair cells following chronic aminoglycoside treatment.

Although aminoglycosides have been investigated for their cochleotoxicity, it has still not been determined whether apoptosis or necrosis results in cochlear hair cell death following aminoglycoside treatment. To study possible mechanisms of cell death, we used in situ DNA break-labeling to examine guinea pig cochleae affected by Kanamycin ototoxicity. Chronic kanamycin treatment induced DNA fragmentation that was detectable in both outer and inner hair cells, suggesting the occurrence of apoptosis. These findings suggest that apoptosis achieves deletion of affected hair cells without disrupting tissue architecture in the organ of Corti.

Animals↗
PubMed1998

Cloning and characterization of cDNAs encoding S-RNases from almond (Prunus dulcis): primary structural features and sequence diversity of the S-RNases in Rosaceae.

cDNAs encoding three S-RNases of almond (Prunus dulcis), which belongs to the family Rosaceae, were cloned and sequenced. The comparison of amino acid sequences between the S-RNases of almond and those of other rosaceous species showed that the amino acid sequences of the rosaceous S-RNases are highly divergent, and intra-subfamilial similarities are higher than inter-subfamilial similarities. Twelve amino acid sequences of the rosaceous S-RNases were aligned to characterize their primary structural features. In spite of their high level of diversification, the rosaceous S-RNases were found to have five conserved regions, C1, C2, C3, C5, and RC4 which is Rosaceae-specific conserved region. Many variable sites fall into one region, named RHV. RHV is located at a similar position to that of the hypervariable region a (HVa) of the solanaceous S-RNases, and is assumed to be involved in recognizing S-specificity of pollen. On the other hand, the region corresponding to another solanaceous hypervariable region (HVb) was not variable in the rosaceous S-RNases. In the phylogenetic tree of the T2/S type RNase, the rosaceous S-RNase fall into two subfamily-specific groups (Amygdaloideae and Maloideae). The results of sequence comparisons and phylogenetic analysis imply that the present S-RNases of Rosaceae have diverged again relatively recently, after the divergence of subfamilies.

Amino Acid Sequence↗
PubMed1998

Spontaneous biloma as a complication of small cell lung cancer.

Biloma is an extraductular collection of bile within a defined capsular space. Prior reports have documented an association between biloma and abdominal trauma, and between biloma and iatrogenic injury resulting from abdominal surgery, percutaneous catheter drainage, or transhepatic cholangiogram. To our knowledge, bilomas have not previously been associated with lung cancer. We report a case of spontaneous biloma that developed as a complication of small cell lung cancer.

Aged↗
PubMed1998

Dose-dependent response of vestibular hair cells of guinea pigs following streptomycin ototoxiation.

Although the involvement of apoptosis has been suggested in the loss of vestibular hair cells due to aminoglycosides, dose-dependent effects of aminoglycosides have not been determined. We therefore examined dose-dependent effects of streptomycin on the degeneration of hair cells of guinea pig ampullar cristae using TUNEL stain and Hoechst nuclear stain. Streptomycin induced apoptosis of hair cells in a dose-dependent manner. Even following high-dose applications, most of the affected cells showed apoptotic features. Apoptosis may therefore play a predominant role in the deletion of vestibular hair cells affected by aminoglycosides.

Animals↗
PubMed1998

Role of amino acids in cochlear degeneration: deprivation of cystine induces death of cochlear hair cells of guinea pigs in vitro.

Redox regulation reportedly plays a role in maintaining cochlear homeostasis. However, little is known about the roles of oxidation-reduction systems in the cochlea. We examined the role of the cystine/cysteine oxidation-reduction system in survival of cochlea hair cells in vitro. The survival of hair cells was evaluated in cochlea specimens following incubation with the medium supplemented with various concentrations of cystine. Dying hair cells were detected by the trypan blue extrusion method. The rates of cell death for both outer and inner hair cells increased significantly with a decrease in the concentration of cystine. In addition, the rate of cell death of IHCs tended to be higher than that of OHCs. These findings suggest that the cystine/cysteine system might be required for maintenance of homeostasis in cochlear hair cells, especially in IHCs.

Animals↗
PubMed1998

Role of amino acids in cochlear degeneration: morphological changes in cochlear outer hair cells following glutamate application.

Glutamate is an excitatory neurotransmitter in the cochlea and has toxic effects on the organ of Corti in various pathological conditions. The toxic effects of glutamate have not been determined in detail. In this study, we examined morphological changes in the organ of Corti of guinea pigs following local application of glutamate. Morphological changes were noted in outer hair cells. Degeneration of outer hair cells was found 24 h after glutamate treatment. The extent of degeneration depended on exposure time. Inner hair cells did not exhibit any degeneration. In addition, no degenerative changes were detected in nerve endings attached to hair cells. These findings suggest that outer hair cells are the initial site of degeneration caused by application of excess glutamate to the inner ear.

Animals↗
PubMed1998

Time-dependent response of vestibular hair cells of guinea pigs following high-dose applications of streptomycin.

Apoptosis has been reported to occur in vestibular hair cells following aminoglycoside treatment and is suggested to play a predominant role in deletion of affected hair cells. However, the type of cell death occurring during an acute phase of vestibular damage following high-dose application of streptomycin has not yet been determined. Hence, in this study we examined the cell death mode of vestibular hair cells during the acute phase. The numbers of hair cell nuclei stained by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) method and residual hair cells were quantitatively analysed. Hoechst nuclear staining was used for analysis of the nuclear morphology of affected hair cells. TUNEL staining of hair cell nuclei and lost hair cells began to appear 6 h after streptomycin treatment and increased with more exposure time. Apoptotic nuclear features could also be found from 6 h after streptomycin treatment. These findings support the thesis that apoptosis is a predominant cell death mode in degeneration of vestibular hair cells due to streptomycin ototoxicity.

Animals↗
PubMed1998

Cycloheximide blocks the toxic effect of streptomycin in guinea pig vestibular hair cells.

Apoptosis has been suggested to be a predominant cell death process for streptomycin-induced degeneration of vestibular hair cells. However, the biochemical aspects of this have not been studied. The purpose of this study was to examine the biochemical aspects of apoptosis of vestibular hair cells caused by streptomycin. Cycloheximide is a widely used protein synthesis inhibitor in studies of apoptosis. We therefore investigated cycloheximide effects on degeneration of vestibular hair cells following streptomycin applications. Supplements of cycloheximide significantly prevented DNA fragmentation in hair cell nuclei and reduced the loss of hair cells. This suggests that cycloheximide possibly inhibits apoptosis of hair cells and attenuates streptomycin-induced degeneration of the vestibular epithelium.

Animals↗
PubMed1998

Clinical value of MRA analysis of the vertebrobasilar system in vertiginous patients.

Vertebrobasilar haemodynamics correlate closely with syndromal vertigo. The aim of this study is to examine the clinical value of MRA for evaluation of vertebrobasilar haemodynamics in vertiginous patients. We examined 40 individuals (20 with vertebrobasilar insufficiency and 20 diagnosed with other vestibular disorders). MRA results were quantified on the basis of the severity of vascular stenosis in the major arteries of the vertebrobasilar system and we analysed the relationship of these results with otoneurological diagnoses, eye-tracking tests (ETT) and optokinetic nystagmus (OKN). MRA results correlated well with otoneurological diagnoses and ETT results. Consequently, MRA can be used as a screening examination to evaluate vertebrobasilar haemodynamics and ETT may be a sensitive functional parameter of vertebrobasilar insufficiency.

Adult↗
PubMed1998

Evaluation of the vertebrobasilar artery system by magnetic resonance angiography in the diagnosis of vertebrobasilar insufficiency.

To evaluate the advantages of magnetic resonance angiography (MRA) in assessing the vertebrobasilar artery system for diagnosing vertebrobasilar insufficiency (VBI), we compared the MRA results of middle-aged and older VBI cases with those of age-matched peripheral disorder cases. There were no significant differences in the rate of complications associated with atherosclerosis between VBI cases and peripheral disorder cases. The MRA results were quantitatively assessed by scores determined on the basis of the severity of stenosis in the vertebral arteries and basilar artery. The MRA score was defined as the total score of these three arteries. The severity of stenosis and the MRA score of VBI cases were significantly higher than those of peripheral cases. MRA can therefore be of value as a screening examination for estimating vertebrobasilar blood flow and can provide helpful information for diagnosing VBI.

Aged↗
PubMed1998

Quantitative analysis of correlation between smooth pursuit and vertebrobasilar hemodynamics.

The cerebellar arterial system is derived from the vertebrobasilar system. However, the relation between cerebellar function and vertebrobasilar hemodynamics remains poorly understood. In this study on patients with vertebrobasilar insufficiency symptoms we examined the relation between magnetic resonance angiography (MRA) abnormalities in the vertebrobasilar system and smooth pursuit function, which is a sensitive parameter of cerebellar function. MRA abnormality was quantitatively assessed on the basis of the severity of stenosis in the vertebral arteries and basilar artery, and on the visualization of the superior cerebellar arteries. Smooth pursuit dysfunction was quantified by the combined amplitude of spikes on an electronystagmograph. A significant correlation was found between MRA abnormality and smooth pursuit dysfunction. This suggests that smooth pursuit dysfunction is closely related to static factors of dysregulation of vertebrobasilar blood flow. Therefore, smooth pursuit can be valued as a sensitive parameter to dysfunction of vertebrobasilar blood flow.

Aged↗
PubMed1998

Comparative assessment of cell proliferation and accumulation of extracellular matrix in nasal polyps.

In nasal polyps constantly associated with chronic inflammation, a dysregulation of epithelial cell proliferation has been described. Involvement of extracellular matrix accumulation is also suggested in the formation and growth of nasal polyps. In this study, we attempted to evaluate the activity of the proliferation of epithelial cells and fibroblasts and the relation between fibronectin accumulation and these cell proliferations in nasal polyps. The pathological specimens of 30 patients were examined which manifested proliferating cell nuclear antigen (PCNA) expression in epithelial cells and fibroblasts and in fibronectin expression. PCNA expression was quantified by calculating the index for each sample. No significant difference in PCNA index was found between epithelial cells and fibroblasts. However, a significant correlation was found between the epithelial and fibroblastic PCNA index. In addition, fibronectin immunopositivity was well correlated with the activity of proliferation of fibroblasts. Therefore, proliferation of fibroblasts is also an important factor in the growth of nasal polyps, and its relationship with fibronectin accumulation may play a role in the pathogenesis of nasal polyposis.

Adult↗
PubMed1998

Characterization of a protein kinase gene responsive to auxin and gibberellin in cucumber hypocotyls.

By means of the PCR, cDNA clones encoding putative protein kinases have been obtained from cucumber hypocotyls. The abundance of the transcript of one of these genes, which was named CsPK3, increased on treatment with gibberellin (GA4) and/or auxin (IAA). We screened a cucumber cDNA library to clone CsPK3 cDNA. The cDNA clone (cCsPK3) encodes an open reading frame of 1,413 bp (471 amino acids), and its predicted amino acid sequence showed homology with those of serine/threonine protein kinases. Northern blot analysis indicated that IAA was more active than GA4 in increasing the level of CsPK3 mRNA in cucumber hypocotyls and that the increase in the level of CsPK3 mRNA on treatment with IAA was not inhibited by pretreatment with a protein synthesis inhibitor. The level of CsPK3 mRNA was high in hypocotyls of dark-grown cucumber seedlings and decreased to less than 50% of the original level within 15 min of the start of irradiation with white light.

Amino Acid Sequence↗
PubMed1998

Assessment of hair cell death using the dye extrusion method.

We examined the usefulness of the dye extrusion method for assessing cochlear hair cell death in guinea pigs. Unilateral temporal bones were incubated in sterile Dulbecco modified Eagle's medium for 1-6 h and then perfused with PBS/0.3% trypan blue to determine hair cell viability. Cells with nuclei stained with trypan blue were assumed to have died. The contralateral temporal bones of each animal were incubated with the same medium for 1-6 h and examined by transmission electron microscopy (TEM). This method revealed that hair cell viability under these conditions was maintained for at most 3 h. After incubation for more than 3 h, hair cell injury began and increased. After 6 h incubation, TEM revealed apoptotic death of outer hair cells. The results with this method agreed with the TEM findings. The dye extrusion method is simple, easy and useful for screening hair cell death in the cochlea under pathological conditions.

Animals↗
PubMed1998

Cleavage product from the NO donor NOC-5 and inner ear hair cell damage.

Nitric oxide (NO) is a neurotoxic gas which causes neuronal cell death. NO ototoxicity has also been reported, 1-Hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene (NOC-5), NO donor, was used for studying NO. In this in vitro study, we examined whether NOC-5 and the cleavage products arising from it after production of No have ototoxic effects on the cochlea. The temporal bones of 55 guinea pigs were dissected and incubated in Dulbecco Modified Eagle's Medium (DMEM) with low glucose and 10% foetal bovine serum (FBS) perfused with various concentrations (100, 50, 10, 1 mM, 100 microM) of NOC-5 (pH 7.4) or the same concentrations of N-isopropyl 1-3 propanildiamine (R-NH2). Hair cell death was assessed using trypan blue staining. With NOC-5, percentages of outer hair cell death were 99.2, 98.0, 45.2, 40.5, and 20%, respectively, and percentages of inner hair cell death were 69.3, 70.2, 22.5. 11.1 and 0%, respectively. With R-NH2, percentages of outer hair cell death were 90.3, 81.1, 29.8, 21.0 and 19.3%, respectively, and percentages of inner hair cell death were 61.4, 48.1, 10.2, 5.4 and 0%, respectively. Ultramicroscopic examination showed that hair cell death was necrotic. Although NOC-5 is useful for study of NO, its cleavage products are also ototoxic.

Animals↗