Biomedical subjects

T Kubo

Publications and source records attributed to T Kubo.

At least 361 records · Page 20Linked to original sources

PubMed1998

Sound lateralization and speech discrimination in patients with sensorineural hearing loss.

Sound lateralization and speech discrimination abilities are both closely related to central auditory system function. In this study, we investigated the relationship between sound lateralization and speech discrimination in patients with sensorineural hearing loss (SNHL) of unknown aetiology or presbycusis. Interaural intensity difference (IID) and interaural time difference (ITD) discriminations were measured using a self-recording apparatus for dichotic sound presentation, and the means of bilateral maximum scores in speech discrimination tests were calculated. Subjects with normal sound lateralization had good speech discrimination scores above 70%, while those with abnormal sound lateralization had poor scores below 70%. Some patients, however, had good speech discrimination but abnormal sound lateralization. These findings were obtained in both IID and ITD discrimination tests. Furthermore, some subjects could not discriminate ITD, although all could discriminate IID. These findings suggest that sound lateralization ability may be affected more than speech discrimination in SNHL of unknown aetiology or in presbycusis.

Adult↗

PubMed1998

Patterns of change in growth function of distortion product otoacoustic emissions in Menière's disease.

The patterns of change in the growth function of distortion product otoacoustic emissions (DPOAEs) associated with hearing improvement in six patients with Menière's disease were investigated. The growth functions of 2F1-F2 DPOAEs at F2 frequencies of 1001, 2002 and 4004 Hz (DP-1, DP-2 and DP-4, respectively) were measured with F2 intensities ranging from 70 to 37 dBSPL in 3-dB steps. The F1 intensity was maintained 10 dB higher than the F2 intensity. The growth function was paired with the hearing threshold at the corresponding F2 frequency, and the relationships between changes in DP-1, DP-2 and DP-4 and those in hearing thresholds at 1, 2 and 4 kHz, respectively, were also investigated. The patterns of change in the growth function associated with hearing improvement could be classified into five types. In the first type, the DPOAE growth function became detectable, while the remaining four types were distinguished by combinations of changes in DPOAE amplitudes for lower and higher primary intensities. Multiple parameters, such as maximum amplitude and detection threshold of the growth function, appeared to be required for simple detection and discrimination of these patterns of change. It was also found that the DPOAE growth functions clearly changed in some cases even though the hearing thresholds did not change significantly at the corresponding F2 frequencies. This finding suggests that DPOAE growth function measurement can detect small changes in cochlear function which do not lead to changes in hearing threshold, and has higher sensitivity than pure tone audiometry in monitoring of cochlear function. In conclusion, our findings suggest that measurement of the DPOAE growth function is useful for monitoring cochlear function, and that information on its patterns of change is clinically important and useful.

Adult↗

PubMed1998

Changes in distortion product otoacoustic emissions from ears with Menière's disease.

To investigate changes in distortion product otoacoustic emissions (DPOAEs) associated with hearing improvement in ears with Menière's disease, four parameters were studied. These were: DPOAE amplitudes for a moderate (L1/L2 = 65/55 dBSPL) and a high (L1/L2 = 74/64 dBSPL) primary level (65/55-DP and 74/64-DP amplitudes, respectively); maximum level of DPOAE amplitudes in the growth function (maximum DP level); and DPOAE detection threshold (DP threshold) of the growth function. Significant correlations were found between all four parameters and hearing threshold, except for the 65/55-DP amplitude at 1 kHz, and each parameter appeared to reflect the hearing threshold to some extent. However, the changes in the four parameters associated with hearing improvement were somewhat complicated. Changes could not be evaluated due to lack of detection of responses when the hearing thresholds exceeded 50 dBHL. Findings that parameters became detectable, the DP amplitude or the maximum DP level increased significantly, or the DP threshold lowered significantly were classified as "improved" findings. The number of ears with "improved" findings was larger for the maximum DP level or the DP threshold than for the 65/55-DP and 74/64-DP amplitudes in ears with a 10 dB or greater improvement in hearing threshold at the corresponding F2 frequency. Furthermore, a significant decrease in amplitude was found in some ears, although the hearing threshold was not elevated when the 65/55- or 74/64-DP amplitude was used as a parameter. On the other hand, "improved" findings for the maximum DP level or the DP threshold were observed for a relatively large number of ears without a significant change in hearing threshold, and it was thought that small changes in cochlear function which did not lead to changes in hearing threshold were detected by changes in DPOAEs. These findings suggest that parameters determined from the growth function, such as maximum DP level and DP threshold are better indicators for monitoring cochlear function than is DPOAE amplitude for a single primary level, and demonstrate the usefulness of the growth function measurement for monitoring purposes. Furthermore, evaluation by changes in the overall growth function using combined parameters appeared to increase sensitivity in detection of subtle changes in cochlear function. In conclusion, DPOAE measurement can be a useful examination for clinical monitoring of cochlear function in Menière's disease when the growth function is measured.

Adolescent↗

PubMed1997

Change in the mode of gene expression of the hypopharyngeal gland cells with an age-dependent role change of the worker honeybee Apis mellifera L.

Major proteins synthesized in the hypopharyngeal gland of the worker honeybee change from bee-milk proteins to alpha-glucosidase in accordance with the age-dependent role change of the worker bee. Previously, we showed that the gene for alpha-glucosidase is expressed specifically in the forager-bee gland [Ohashi, K., Sawata, M., Takeuchi, H., Natori, S. & Kubo, T. (1996) Biochem. Biophys. Res. Commun. 221, 380-385]. Here, we describe the isolation and analysis of cDNAs for two bee-milk 56-kDa and 64-kDa proteins. The 56-kDa protein was a glycoprotein which shared 63.2% and 56.9% amino acid sequence identities with proteins encoded by cDNA for royal-jelly-related protein 57-1 (pRJP57-1) and pRJP57-2. The 64-kDa protein cDNA was identical to pRJP57-1. Thus, these bee-milk proteins seem to form a structurally related protein family. The gene for the 64-kDa protein/RJP57-1 was expressed specifically in the nurse-bee gland, whereas that for the 56-kDa protein was expressed in both the nurse-bee and forager-bee glands. mRNAs for the 56-kDa and 64-kDa proteins were detected by in situ hybridization in a whole acinus of the nurse-bee gland, whereas mRNAs for the 56-kDa protein and alpha-glucosidase were detected in that of the forager-bee gland. Therefore, the individual secretory cells of the acinus of the hypopharyngeal gland were shown to express these genes differently with the age-dependent role change of the worker bee.

Aging↗

PubMed1997

Identification of the region in yeast S-II that defines species specificity in its interaction with RNA polymerase II.

Yeast S-II was found to stimulate yeast RNA polymerase II only and not mouse RNA polymerase II. To identify the molecular region of S-II that defines species specificity, we constructed six hybrid S-II molecules consisting of three regions from yeast and/or Ehrlich cell S-II and examined their activity in terms of RNA polymerase II specificity and suppression of 6-azauracil sensitivity in the yeast S-II null mutant. We found that the region 132-270 (amino acid positions) of yeast S-II is indispensable for specific interaction with yeast RNA polymerase II in vitro and for suppression of 6-azauracil sensitivity in vivo. The corresponding region of Ehrlich cell S-II, the region 132-262, was also shown to be essential for its interaction with mouse RNA polymerase II. This region is known to be less conserved than the N- and C-terminal regions in the S-II family suggesting that it is important in the interaction with transcription machinery proteins in a tissue and/or species-specific manner.

Amino Acid Sequence↗

PubMed1997

Evidence for the involvement of endogenous aspartate in the mediation of carotid chemoreceptor reflexes in the rostral ventrolateral medulla of the rat.

2-Amino-5-phosphonovalerate (AP5; 153 pmol) injected into the rostral ventrolateral medulla (RVLM) inhibited pressor responses induced by carotid chemoreceptor stimulation. AP5 also inhibited pressor responses to aspartate (0.75 nmol) but not to glutamate (0.53 nmol) similarly injected. High K+ (50 mM) released endogenous aspartate and glutamate in a Ca2+-dependent manner from the RVLM. Chemoreceptor stimulation caused a release of aspartate but not of glutamate in the RVLM, and sinus nerve denervation abolished the release of aspartate. Increases in blood pressure induced by intravenous phenylephrine did not release aspartate. These results support the hypothesis that endogenous aspartate in the rat RVLM is involved in the mediation of chemoreceptor reflexes.

2-Amino-5-phosphonovalerate↗

PubMed1997

Changes in nitric oxide synthase-like immunoreactivities in unipolar brush cells in the rat cerebellar flocculus after unilateral labyrinthectomy.

To elucidate the role of nitric oxide (NO)-mediated signaling in vestibular compensation, we examined effects of unilateral labyrinthectomy (UL) on the neuronal isoform of NO synthase (NOS) expression in the rat central vestibular system using immunohistochemical techniques. After UL, a substantial number of NOS-like immunoreactive (-LIR) neurons were observed in the granule cell layer in bilateral flocculi, and these neurons were determined to be unipolar brush cells (UB cells) by their unique morphology and location. NOS-LIR UB cells appeared by 12 h with a maximum increase in number 24 h after UL, and then gradually disappeared in accordance with the development of vestibular compensation. Continuous floccular infusion of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NOS, or 2-phenyl-4,4,5,5-tetramethyl-1-oxyl-3-oxide (PTIO), an inhibitor of NO, caused more severe vestibulo-ocular deficits at the initial stage after UL and slightly delayed the recovery from these symptoms. All these findings suggest that up-regulation of NO production in floccular UB cells facilitates vestibular compensation, especially at the initial stage after UL.

Animals↗

PubMed1997

Involvement of phosphatidylinositol-3 kinase in prevention of low K(+)-induced apoptosis of cerebellar granule neurons.

Cerebellar granule neurons obtained from 9-day-old rats die in an apoptotic manner when cultured in serum-free medium containing a low concentration of potassium (5 mM). A high concentration of potassium (26 mM) in the culture medium and BDNF can effectively prevent this apoptosis. The survival effects of high potassium and BDNF were additive, and the effect of high potassium was not blocked by addition of anti-BDNF antibody. These observations indicated that these survival effects were independent. To examine which molecules are involved in the survival pathway induced by BDNF or high K+, we used wortmannin, a specific inhibitor of PI-3 kinase. Wortmannin blocked the survival effects of both BDNF and high K+ on cerebellar granule neurons. Furthermore, in vitro PI-3 kinase assay showed that treatment with BDNF or high K+ induced PI-3 kinase activity, which was diminished by addition of wortmannin. These results indicate that different survival-promoting agents, BDNF and high K+, can prevent apoptosis in cerebellar granule neurons via a common enzyme, PI-3 kinase.

Androstadienes↗

PubMed1997

An ATP-dependent inwardly rectifying potassium channel, KAB-2 (Kir4. 1), in cochlear stria vascularis of inner ear: its specific subcellular localization and correlation with the formation of endocochlear potential.

Cochlear endolymph has a highly positive potential of approximately +80 mV. This so-called endocochlear potential (EP) is essential for hearing. Although pivotal roles of K+ channels in the formation of EP have been suggested, the types and distribution of K+ channels in cochlea have not been characterized. Because EP was depressed by vascular perfusion of Ba2+, an inhibitor of inwardly rectifying K+ (Kir) channels, but not by either 4-aminopyridine or tetraethylammonium, we examined the expression of Kir channel subunits in cochlear stria vascularis, the tissue that is supposed to play the central role in the generation of positive EP. Of 11 members of the Kir channel family examined with reverse transcription-PCR, we could detect only expression of KAB-2 (Kir4.1) mRNA in stria vascularis. KAB-2 immunoreactivity was specifically localized at the basolateral membrane of marginal cells but not in either basal or intermediate cells. Developmental expression of KAB-2 in marginal cells paralleled formation of EP. Furthermore, deaf mutant mice (viable dominant spotting; WV/WV) expressed no KAB-2 in their marginal cells. These results suggest that KAB-2 in marginal cells may be critically involved in the generation of positive EP.

4-Aminopyridine↗

PubMed1997

Enhanced induction of very late antigen 4/lymphocyte function-associated antigen 1-dependent T-cell migration to tumor sites following administration of interleukin 12.

Administration of interleukin 12 (IL-12) into mice bearing CSA1M, OV-HM, Meth A, or MCH-1-A1 tumor induced complete regression of CSA1M and OV-HM tumors but induced only a slight growth inhibition of Meth A and MCH-1-A1 tumors. These effects of IL-12 were associated with high and only marginal levels of T-cell infiltration into CSA1M/OV-HM and Meth A/MCH-1-A1 tumor masses, respectively. Here, we investigated the role of IL-12 in the induction of T-cell migration. Spleen cells from untreated or IL-12-treated CSA1M-bearing mice were stained in vitro with a fluorescein chemical and transferred i.v. into IL-12-untreated CSA1M-bearing mice. Migration of donor cells was quantitated by counting the number of fluorescent cells on cryostat sections of tumor masses. Although only a slight migration was detected for spleen cells from IL-12-untreated CSA1M-bearing as well as IL-12-treated or untreated normal mice, enhanced migration was observed for cells from IL-12-treated CSA1M-bearing mice. A similar enhanced migration was observed for the OV-HM model. In contrast, such an enhancement was only marginal in the Meth A and MCH-1-A1 models. Immunohistochemical studies of tumors from IL-12-treated mice revealed that the predominant T-cell subset was CD4+ in CSA1M and CD8+ in OV-HM tumor masses. Consistent with this observation, the dominant subset of migrating T cells was found to be CD4+ in the CSA1M and CD8+ in the OV-HM models. T-cell migration was inhibited by pretreatment of recipients with either combination of anti-very late antigen 4 + anti-vascular cell adhesion molecule 1 or anti-lymphocyte function-associated antigen 1 + anti-intercellular adhesion molecule 1 monoclonal antibody. These results indicate that IL-12 can confer T cells with a capacity to migrate to tumor sites through very late antigen 4/lymphocyte function-associated antigen 1 adhesion pathways and that the in vivo acquisition of such a capacity following IL-12 treatment correlates with the induction of tumor regression.

Animals↗

PubMed1997

Molecular cloning of cDNA for lysenin, a novel protein in the earthworm Eisenia foetida that causes contraction of rat vascular smooth muscle.

Lysenin, which causes contraction of rat vascular smooth muscle, is a protein that was isolated from the earthworm Eisenia foetida. A cDNA encoding lysenin was isolated by use of a partial cDNA probe that had been generated by the PCR with a primer designed by reference to an internal peptide sequence of lysenin. This clone had an ORF encoding 297 amino acid residues. The amino acid sequence deduced from the cDNA revealed the absence of any significant homology to those of previously characterized vasoactive substances. The recombinant lysenin was produced in Escherichia coli. This protein and native lysenin isolated from the earthworm had similar contractive activities when tested on rat aorta. Northern blot analysis of the RNA from various tissues of the earthworm indicated that lysenin is produced by the coelomocytes.

Amino Acid Sequence↗

PubMed1997

Ribozyme-based gene cleavage approach to chronic arthritis associated with human T cell leukemia virus type I: induction of apoptosis in synoviocytes by ablation of HTLV-I tax protein.

OBJECTIVE: To develop gene therapy for patients with human T cell leukemia virus type I (HTLV-I)-associated arthropathy (HAAP), we investigated the effects of ribozyme-mediated cleavage of HTLV-I tax/rex messenger RNA (mRNA) on synovial overgrowth. METHODS: We introduced 2 hammerhead ribozymes targeted against HTLV-I tax/rex mRNA into synovial cells obtained from patients with HAAP and from patients with HTLV-I-negative rheumatoid arthritis (RA) and examined the ribozyme-mediated ablation of Tax expression. Using standard methods, we also determined the cells' ability to stop proliferating and to undergo apoptosis. RESULTS: The ribozymes successfully cleaved tax/rex mRNA in HAAP patient synoviocytes. Both tax mRNA expression and Tax protein synthesis were inhibited significantly, resulting in inhibition of synovial cell growth and induction of apoptosis. In contrast, synovial cells from RA patients were not affected. CONCLUSION: In vitro results suggest that ribozyme-mediated gene therapy can inhibit the growth of HTLV-I-infected synovial cells, which is maintained by Tax protein, in HTLV-I-related diseases including HAAP.

Apoptosis↗

PubMed1997

Hydrostatic pressure influences mRNA expression of transforming growth factor-beta 1 and heat shock protein 70 in chondrocyte-like cell line.

The present study investigated the influence of hydrostatic pressure on the expression of cytokines and heat shock protein 70 in a chondrocyte-like cell line. Chondrocyte-like cells (HCS-2/8) were exposed to hydrostatic pressure by a special pressure apparatus. Total RNA for cytokines (interleukin-1 beta, basic fibroblast growth factor, insulin-like growth factor-I, and transforming growth factor-beta 1) and for heat shock protein 70 was extracted and was analyzed by a polymerase chain reaction method and Northern blotting. An assay for incorporation of [35S]sulfate was performed to assess proteoglycan synthesis. The expression of transforming growth factor-beta 1 mRNA was enhanced after exposure to 5-MPa of hydrostatic pressure and was reduced after 50 MPa, whereas the expression of heat shock protein 70 was enhanced following exposure to 50 MPa of hydrostatic pressure. The incorporation of [35S]sulfate into the cultured cells increased following exposure to 1-5 MPa of hydrostatic pressure and decreased following 10-50 MPa of pressure. These results suggest that hydrostatic pressure at physiologic levels enhances the expression of transforming growth factor-beta 1 mRNA in addition to increasing proteoglycan synthesis in chondrocytes and that excessively high hydrostatic pressure reduces the expression of transforming growth factor-beta 1 mRNA and increases the expression of heat shock protein 70 mRNA while decreasing proteoglycan synthesis.

Cartilage, Articular↗

PubMed1997

Method of histomorphometric assessment of glycosaminoglycans in articular cartilage.

A method of image analysis has been developed for use in the semiquantitative histomorphometric assessment of glycosaminoglycans in articular cartilage stained with safranin O. The reliability of the methodology is reported along with its application to the assessment of articular cartilage in a model of osteoarthritis, i.e., transection of the anterior cruciate ligament in rabbits. With this system, specimens of normal and osteoarthritic articular cartilage were assessed histomorphometrically for the following parameters: total cartilage area, percentage of safranin O stained area, mean gray scale (average stain intensity), and gray scale index (the relative total amount of glycosaminoglycans). Reproducibility was established for 12 specimens of normal cartilage and found to have a SD of less than 8% of the mean for each parameter that was measured. Image analysis of osteoarthritic cartilage revealed each of the parameters, except for average stain intensity, to be significantly lower than that in control cartilage.

Animals↗

PubMed1997

Histamine release from the hypothalamus induced by gravity change in rats and space motion sickness.

Freely moving rats were exposed to 2 g hypergravity in an animal centrifuge device to produce motion sickness. Histamine release from the anterior hypothalamus of the rats was measured in vivo with a microdialysis technique. After a 2-h load of 2 g hypergravity, rats ate kaolin. Because pica, eating a nonnutritive substance such as kaolin, is a behavioral index of motion sickness in rats, this finding indicates that the rats suffered from motion sickness. During 2 g hypergravity for 2-h, histamine release from the hypothalamus was transiently increased. In contrast, neither the transient increase of histamine release nor the kaolin consumption were induced by 2 g hypergravity in bilaterally labyrinthectomized rats. Pretreatment with alpha-fluoromethylhistidine, an inhibitor of histamine-synthesizing enzyme, decreased both the basal and hypergravity-induced releases of histamine from the hypothalamus and suppressed the kaolin consumption induced by hypergravity. Taken together, these findings suggest that the vestibular information of changes in gravity activate the histaminergic neuron system, resulting in the development of motion sickness. More prolonged stimulation, a 4-h load of 2 g hypergravity, induced significant increase of kaolin consumption on postdays 1-3, though rats ate kaolin on postdays 1-2 after 2 g hypergravity for 2 h. During 2 g hypergravity for 4 h, the initial transient increase of histamine release was followed by the gradual increase of histamine release after the end of centrifugation. It is suggested that rats adapted to the hypergravity environment after centrifugation for 4 h, but not 2 h, so that the change in gravity from 2 g to 1 g became a provocative stimulation. We, therefore, concluded that motion sickness in rats induced by a negative change in gravity can be used as a simulation of space motion sickness, which is induced by exposure to microgravity. Histaminergic activation in the development of motion sickness induced by negative change in gravity might be an underlying mechanism of space motion sickness.

Animals↗

PubMed1997

A case of giant cell reparative granuloma of the petrous bone: demonstration of the proliferative component.

BACKGROUND: Giant cell reparative granuloma (GCRG) is an uncommon benign lesion of the bone. It typically arises in the mandible and rarely involves the skull. The cytologic nature and genesis of the involved cells are poorly understood. METHODS AND RESULTS: We report a case of GCRG in the petrous bone of a 3-year-old girl. One year following gross total removal, the granuloma recurred locally and was resected en bloc at the second surgery. Histologically, the lesion was composed of oval or spindle-shaped stroma cells admixed with a number of multinucleated giant cells. Immunohistochemical study demonstrated that 5.6% of the stroma cells, but none of the multinucleated giant cells, were positive for MIB-1 antibody. CONCLUSION: These results suggest that this lesion expands by proliferation of the stromal component, with a growth rate roughly between those of the typical benign and malignant brain tumors. The cytologic nature of the cells comprising this uncommon disease remains to be elucidated.

Child, Preschool↗

PubMed1997

Hippocampal degeneration inducing impairment of learning in rats: model of dementia?

In the pharmacological field, the development of drugs effective for dementia is now widely anticipated because of the increase in the elderly population. Dementia has some histological degeneration in the brain, including the hippocampus. Preclinical evaluations of such drugs use animal models with memory impairment, since memory impairment is a major criterion of dementia. We therefore investigated two animal models with hippocampal degeneration. Neonatal administration of monosodium glutamate (MSG) induced specific degeneration of hippocampal pyramidal cells in the CA1 region of Wistar rats in adulthood. In these animals, the correct response rate during the acquisition period of light-dark discrimination learning was significantly lower than that in the control group. No significant changes were noted in the hippocampal concentrations of neurotransmitter substances, including acetylcholine and glutamate. In the second model, similar histological changes were observed at 3 weeks after oral administration of trimethyltin (TMT). These histological changes were accompanied by a reduction in the intrahippocampal concentrations of acetylcholine and glutamate. In the case of light-dark discrimination learning, neither pre- nor post-training administration of TMT affected the correct response rate during both the acquisition and retention test periods. In the case of 8-arm radial maze learning, the increase in correct response rate was significantly suppressed in comparison with that of the control group when TMT was administered at 4 weeks before starting the acquisition trial. This suppression was followed by a lower response rate in the retention test. On the other hand, the correct response rates in retention tests were not affected when TMT was administered after completion of the acquisition trial. These findings indicate that sole degeneration of the hippocampus was able to induce different types of memory impairment, and single evaluation of a drug with one learning paradigm was difficult to justify that a drug is effective for dementia.

Animals↗

PubMed1997

Rat corpus luteum expresses both PACAP and PACAP type IA receptor mRNAs.

Both pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP type I receptor gene expressions were detected in the corpus luteum of pregnant mare's serum gonadotropin (PMSG)-human chorionic gonadotropin (hCG)-treated immature rats using reverse transcription-polymerase chain reaction (RT-PCR). RT-PCR products of the poly(A)+ RNA extracted from rat corpora lutea yielded dominant DNA bands that corresponded to segments of PACAP mRNA (453 bp) and PACAP type IA receptor mRNA (290 bp) spanned by the PCR primers. The identities of the PACAP cDNA and the PACAP receptor cDNA fragments were confirmed by Southern blot hybridization analyses. Our results showed that PACAP mRNA and PACAP type IA receptor mRNA are synthesized within luteinized cells of rat ovary, and suggest that PACAP is closely linked to the reproductive process.

Animals↗