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T Taira

Publications and source records attributed to T Taira.

At least 91 records · Page 5Linked to original sources
PubMed1996

Design of an acclimation system capable of controlling carbon dioxide concentration.

The production system for grafted seedlings mainly consists of three processes; 1) growth of seedlings, 2) grafting of seedlings, and 3) acclimation of grafted seedlings. Of the three processes, the duration of acclimation is highly influenced by the acclimation conditions. The acclimation environment after grafting was controlled to be satisfied the demands of grafted seedlings in the point of the physiological reaction such as photosynthesis, respiration, transpiration, and translocation nutrients. In the present study, a preliminary experiment was conducted to understand the relationship between the factors concerned with the acclimation of grafted seedlings, using a new acclimation apparatus. The factors of interest were air temperature, relative humidity, light, and carbon dioxide concentration. In the presence of light, the air temperature and relative humidity were interfered each other, so that both factors were difficult to keep at a constant value. Furthermore, the concentration of carbon dioxide was remarkably fluctuated by the relative humidity regulated by the humidifier and dehumidification which was controlled by the temperature differences between water and ambient air. A new device of acclimation system which is automatically controlled would be expected to construct in near future. Such a device will make it possible to shorten the duration of acclimation and produce high quality of grafted seedlings.

Acclimatization↗
PubMed1996

[Role of apoptosis in the progression of secondary hyperparathyroidism].

In many tissues, cell proliferation is counterbalanced by apoptosis. Hyperparathyroidism is one of the most important complications in long term dialysis patients and is characterized by remarkable cell proliferation of parathyroid cells. Therefore, alteration in the regulation and clearance of excess cells by apoptosis may occur in hyperparathyroidism. In the present study, we evaluated the expression of Ki-67 (proliferative cell associated protein) and Bcl-2(apoptosis-preventing molecules), and the number of apoptotic cells in the nodular lesion of parathyroid glands with secondary hyperparathyroidism(2 degrees HPT), as compared with primary hyperparathyroidism(1 degree HPT) for clarification of the role of apoptosis in the development of 2 degrees HPT. The number of Ki-67+ cells was remarkably increased in 2 degrees HPT(12.02 +/- 10.87, mean +/- SD) compared to in 1 degree HPT(0.81 +/- 0.53) (p < 0.01). However, the number of apoptotic cells was significantly decreased in 2 degrees HPT(0.10 +/- 0.06) compared to in 1 degree HPT(0.31 +/- 0.19) (p < 0.05). To the contrary, Bcl-2+ cells were increased in 2 degrees HPT(0.35 +/- 0.23) compared to in 1 degree HPT(0.10 +/- 0.13) (p < 0.05). These results suggest that the mechanisms of parathyroid cell proliferation are different in each nodular lesion of 1 degree HPT and 2 degrees HPT. Furthermore, the remarkable proliferation of parathyroid glands may have been due to the reduction of the apoptotic process via Bcl-2 expression in 2 degrees HPT.

Adult↗
PubMed1996

[Lessons from experience of bertrand's selective peripheral denervation for splenius type torticollis].

A 23-year-old male with splenius type torticollis underwent selective denervation of C1 and C2 roots and C3-C6 spinal posterior rami, with excellent results. Based on this experience, we stress the importance of dynamic EMG and thorough review of video recording for identifying the involved neck muscles. In the operative procedures, the nerve rami are identified under the semispinalis muscle. To dissect the correct plane under the semispinalis muscle, the key point to keep in mind is to follow the great occipital nerve to the proximal part. An ultrasonic blood flow meter is useful to locate the vertebral artery in the spaces between the occiput and the C1 lamina and between C1-C2 laminae. Because fine nerve branches run in the soft tissues over the laminae, to avoid transient neuroapraxia, dissection around the C1, C2 arches should not be carried out under the periosteum, as is usually done in case of laminectomy. Dissection of C1 and C2 rami as far as the very medial part is rather difficult because of bleeding from the venous plexus and the presence of the vertebral artery. Therefore, the intradural approach might be easier for sectioning the C1 and C2 roots. We would like to add these points to the original description by Bertrand.

Adult↗
PubMed1996

Correlation between MR image characteristics and histological features of acoustic schwannoma.

We retrospectively studied 21 cases of histologically proven acoustic shwannomas with an emphasis on the correlation of their magnetic resonance imaging (MRI) findings and histological features. All cases were of low signal intensity in the T1W MRI. In the T2W MRI, 9 of them were of homogeneous high signal intensity (Hom-HSI-T2) and 12 of them were of heterogeneous high signal intensity (Het-HSI-T2). The cases of Hom-HSI-T2 were generally associated with capsular enhancement, and were usually cystic tumors with high vascularities and mainly Antoni A tissues. On the contrary, the cases of Het-HSI-T2 were generally associated with homogeneous enhancement, and were usually solid tumors with low vascularities and various tissue components.

Adult↗
PubMed1995

Improved chromatographic purification of human and bovine type V collagen sub-molecular species and their subunit chains from conventional crude preparations. Application to cell-substratum adhesion assay for human umbilical vein endothelial cell.

Two human type V collagen sub-molecular species, designated [alpha 1(V)]2 alpha 2(V) and alpha 1(V)alpha 2(V)alpha 3(V), were purified chromatographically from a commercially available preparation, in which cystine-rich collagenous contaminants were contained, with a column packed with Fractogel EMD SO3-. From bovine crude preparations, the [alpha 1(V)]2 alpha 2(V) form free from the collagenous contaminants was purified. Type V collagen subunit chains were isolated from each type V collagen molecule by anion-exchange HPLC with a Bakerbond PEI Scout column. The highly purified human type V collagen molecules and their subunit chains were used to examine the inhibitory effect on human umbilical vein endothelial cell proliferation. It was confirmed that the alpha 1(V) chain has inhibitory activity and it was found that the inhibitory effect of the [alpha 1(V)]2 alpha 2(V) form is stronger than that of the alpha 1(V)alpha 2(V)alpha 3(V) form and that the alpha 3(V) chain has no inhibitory activity.

Animals↗
PubMed1995

A new approach to the control of central deafferentation pain--spinal intrathecal baclofen.

We investigated the short-term effects of an intrathecal bolus injection of baclofen on central pain due to stroke or spinal cord injury. Pain relief was obtained in 64% of the patients. The effects developed 1-2 hours after the injection and continued for 10-24 hours. Both spinal segmental and supraspinal mechanisms may be involved in the production of baclofen-analgesia.

Afferent Pathways↗
PubMed1995

Effects of monoamine uptake inhibitors given early postnatally on monoamines in the brain stem, caudate/putamen and cortex, and on dopamine D1 and D2 receptors in the caudate/putamen.

Rats were treated with desipramine 5 mg/kg, nomifensine 10 mg/kg, zimelidine 25 mg/kg or with 0.9% sodium chloride once a day during the second and third weeks after birth, and brain stem, caudate/putamen and cortical monoamines, and caudate/putamen dopamine D1 (3[H]SCH 23390) and D2 (3[H]spiroperidol) receptor binding were measured when rats were at two months of age. In the brain stem, the concentration of 3-methoxy-4-hydroxy-phenyl glycol was increased in nomifensine rats and the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in zimelidine rats. In the caudate/putamen, the concentrations of 3,4-dihydroxyphenylacetic acid and homovanillic acid and the ratio of homovanillic acid to dopamine were increased in desipramine rats; neither 3[H]SCH 23390 nor 3[H]spiroperidol binding were affected by any of the three monoamine uptake inhibiting antidepressants studied. In the cortex, the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in desipramine and zimelidine rats. The findings suggest that desipramine but not nomifensine increases the metabolism of dopamine in the caudate/putamen and nomifensine but not desipramine increases the metabolism of norepinephrine in the brain stem, and furthermore that the metabolism of serotonin is affected by desipramine as well as by zimelidine. It is possible that also treatment of women with these drugs during late pregnancy causes long-lasting changes in the brain of human fetus.

Animals↗
PubMed1995

Alterations in brain monoamines and GABAA receptors in transgenic mice overexpressing TGF alpha.

This study investigated the possibility that overexpression of transforming growth factor alpha (TGF alpha) changes those neurotransmitter systems that have been associated with behaviors found to be altered in the transgenic TGF alpha CD-1 mice. The female TGF alpha mice showed elevated levels of norepinephrine (NE) in the hypothalamus and serotonin (5-HT) in the cortex and brain stem when compared with nontransgenic CD-1 females. The concentrations of monoamines were not altered in the male transgenic brain. The 5-hydroxyindoleacitic acid (5-HIAA)/5-HT ratio was significantly reduced in the brain stem of the male TGF alpha mice and frontal cortex in the female transgenics. The binding of the [3H]GBR 12935-labeled DA transporter was lower in the frontal cortex in the transgenic male TGF alpha mice than in the female TGF alpha mice. No gender difference in dopamine (DA) transporter binding was noted between the nontransgenic male and female mice. Serotonin and GABAA receptors were measured only in males. No differences in the number of 5-HT1A and 5-HT2 receptors were found in the cortex or hippocampus. Maximal GABA stimulation of [3H]flunitrazepam binding in the forebrain hemispheres and cerebellar binding of an imidazobenzodiazepine, [3H]Ro 15-4513, were not different between transgenic and nontransgenic male mice. However, forebrain [35S]TBPS binding in male TGF alpha mice was less affected by the blockade of the GABA agonist sites by the specific GABAA antagonists SR 95531 and bicuculline than the binding of the controls, suggesting either altered endogenous GABA concentrations or a change in receptor populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Studies on the role of metabotropic glutamate receptors in long-term potentiation: some methodological considerations.

There has been considerable interest recently in trying to elucidate the roles of metabotropic glutamate receptors (mGluRs) in the induction of long-term potentiation (LTP) in area CA1 of rat hippocampal slices. This has come about principally because of the development of specific mGluR agonists and antagonists. Recently we reported that the competitive mGluR antagonist (+)-alpha-methyl-4-carboxyphenylglycine (MCPG) blocks the induction of LTP but not short-term potentiation (STP). We describe here the dose-dependency of the MCPG block; there is no effect at 100 microM while at 200 microM the block of LTP is normally complete but STP is spared. A higher concentration of MCPG (500 microM) has the same effect as 200 microM. We have also reported recently that high-frequency (tetanic) stimulation conditions a pathway such that MCPG fails to block the induction of subsequent LTP. We illustrate here that the conditioning effect of a tetanus lasts at least 6 h. We show how the pathway can be conditioned, without any persistent change in the synaptic response, by delivering tetanic stimulation in the presence of the specific NMDA receptor antagonist D-2-amino-5-phosphonopentanoate (AP5). The pathway can subsequently be deconditioned by delivering low-frequency stimulation (900 shocks at 2 Hz) so that MCPG blocks the induction of subsequent LTP. We also have reported that the specific mGluR agonist 1-aminocyclopentane-(1S,3R)-dicarboxylate (ACPD) can induce LTP without the need for STP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Activation of alpha 2-adrenergic receptors decreases nerve trauma-induced afferent barrage but not autotomy.

Effects of the selective alpha 2-adrenoceptor agonist, medetomidine, on a compound volley of a tibial nerve stimulation-evoked spinal reflex, pain-induced phrenic motor responses and on postoperative neuropathic pain behavior were studied in rats. Medetomidine (0.3 mg/kg) decreased the amplitude of the compound volley recorded from peroneal nerve in response to tibial stimulation in pentobarbital (40 mg/kg) anesthetized rats. Atipamezole, an alpha 2-adrenoceptor antagonist (1.5 mg/kg) fully restored the response when given 60 min after the medetomidine administration. Pain-evoked phrenic motor responses were completely inhibited upon combination anesthesia by pentobarbital (40 mg/kg) and medetomidine (0.3 mg/kg) (PB+M) but not upon plain pentobarbital anesthesia (50 or 60 mg/kg) (PB50,PB60). To study the effect of medetomidine on postoperative neuropathic pain behavior (autotomy), transection of sciatic nerve was done under PB+M, PB50 or PB60 anesthesia. No differences between the groups were found in the postoperative pain behavior during eight-week follow up. The results show that activation of alpha 2-adrenergic receptors by medetomidine under pentobarbital anesthesia mitigates trauma-induced afferent barrage, whereas it does not reduce the subsequent autotomy.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1995

Strain difference in early postnatal sleep-wake behaviour between Alko Alcohol and Wistar rats.

Early postnatal sleep-wake behaviour of male and female rats of Alko Alcohol and Wistar strain was studied using a static charge sensitive mattress when the rats were aged 1 and 2 weeks postnatally. In both strains and sexes, waking time relative to total recording time increased, proportion of quiet state did not change, and that of active sleep decreased during the second postnatal week. The number of long active sleep stages relative to short active sleep stages and the duration of sleep-wake stages increased with age. Transitions between quiet state and active sleep became fewer with increasing age. Waking time increased more in Wistar rats than in Alko Alcohol rats. At 1-2 weeks of age, the percentage of active sleep and the number of long active sleep stages relative to short active sleep stages were larger, and the duration of sleep-wake stages longer in Alko Alcohol than in Wistar rats. Sleep-wake behaviour did not differ between the sexes of either strain or age. Selective breeding for high alcohol preference in Alko Alcohol rats may have caused a genetic trait in early postnatal sleep-wake behaviour.

Age Factors↗
PubMed1995

Noradrenergic activity in rat brain during rapid eye movement sleep deprivation and rebound sleep.

Noradrenergic locus ceruleus neurons are most active during waking and least active during rapid eye movement (REM) sleep. We expected REM sleep deprivation (REMSD) to increase norepinephrine utilization and activate the tyrosine hydroxylase (TH) gene critical for norepinephrine production. Male Wistar rats were deprived of REM sleep with the platform method. Rats were decapitated after 8, 24, or 72 h on small (REMSD) or large (control) platforms or after 8 or 24 h of rebound sleep after 72 h of the platform treatment. During the first 24 h, norepinephrine concentration, measured by high-performance liquid chromatography/electrochemical detection, was lower in the neocortex, hippocampus, and posterior hypothalamus in REMSD rats than in large-platform controls. After 72 h of REMSD, TH mRNA, measured by in situ hybridization, was increased in the locus ceruleus and norepinephrine concentrations were increased. Polygraphy showed that small-platform treatment caused effective and selective REMSD. Serum corticosterone measurement by radioimmunoassay indicated that the differences found in norepinephrine and TH mRNA were not due to differences in stress between the treatments. The novel finding of sleep deprivation-specific increase in TH gene expression indicates an important mechanism of adjusting to sleep deprivation.

Animals↗
PubMed1995

Pharmacological characterization of extracellular pH transients evoked by selective synaptic and exogenous activation of AMPA, NMDA, and GABAA receptors in the rat hippocampal slice.

1. Inhibitors of extracellular carbonic anhydrase (CAo) offer much promise as diagnostic tools in the study of the synaptic basis of activity-induced alkaline transients in the brain. However, most of the present information related to the effects of CAo blockers in nervous tissue comes from experiments that involve simultaneous synaptic activation of various types of postsynaptic receptor channels. In the present work, double-barreled H(+)-selective microelectrodes were used to study alkaline shifts in extracellular pH (pHo) evoked by selective synaptic and pharmacological activation of glutamate and gamma-aminobutyric acid (GABA) receptors in the CA1 cell body layer in rat hippocampal slices. Inhibition of CAo was achieved with the use of the poorly permeant carbonic anhydrase inhibitor, benzolamide (10 microM; applied in the bath solution) or the impermeant macromolecular inhibitor, prontosil-dextran 5000 (PD 5000; applied in microdrops). 2. Alkaline transients that were exclusively attributable to synaptic activation of glutamate receptors were induced by stimulation of Schaffer collaterals in the presence of picrotoxin (PiTX, 100 microM). An enhancement by the CAo inhibitors of these alkaline transients took place at all stimulus frequencies (5-200 Hz) and stimulus train durations (0.5-20 s) examined. 3. Inhibition of CAo enhanced the alkaline transients evoked by selective synaptic activation of alpha-amino-3-hydroxy-5-methyli-oxazolate- 4-propionic acid (AMPA)/kainate receptors in experiments involving stimulation of Schaffer collaterals in the simultaneous presence of PiTX and D-2-amino-5-phosphonopentoate (AP5, 40-80 microM). 4. Alkaline shifts evoked by selective synaptic activation of N-methyl-D-aspartate (NMDA) receptors were enhanced after inhibition of CAo as seen in experiments where Schaffer collaterals were stimulated in the simultaneous presence of PiTX and 6-cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX, 20-40 microM) in an Mg(2+)-free solution. 5. Benzolamide and PD 5000 also enhanced the alkaline shifts seen upon pressure injection of glutamate, AMPA, or NMDA. The glutamate-induced alkaline shifts were inhibited by AP5+CNQX, suggesting that uptake of glutamate did not significantly contribute to their generation. 6. Stimuli applied at 5-10 Hz in stratum radiatum close (within 0.5 mm) to the recording site evoked alkaline shifts that were blocked by CNQX plus AP5. In the continuous presence of the two glutamate antagonists, PiTX-sensitive alkaline transients were observed in response to brief high-frequency (20-100 Hz) trains consisting of 100 stimuli. Upon application of pentobarbital sodium (100 microM), these apparently monosynaptically evoked GABAA receptor-mediated alkaline transients were evident also at low stimulation frequencies (5-10 Hz).(ABSTRACT TRUNCATED AT 400 WORDS)

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1995

Relative contributions of excitatory and inhibitory neuronal activity to alkaline transients evoked by stimulation of Schaffer collaterals in the rat hippocampal slice.

1. The neuronal basis of alkaline shifts in extracellular pH (pHo) evoked by stimulation of Schaffer collaterals was studied by means of double-barreled H(+)-selective microelectrodes in the area CA1 of rat hippocampal slices. 2. Alkaline transients in stratum pyramidale evoked by stimulation at a low frequency (5-10 Hz) were enhanced by pentobarbital sodium (100 microM). In the absence of the drug, inhibition of extracellular carbonic anhydrase (CAo) by benzolamide or by prontosildextran 5000 (PD 5000) resulted in an increase in the alkaline shifts. In contrast to this, alkaloses evoked by low-frequency stimulation in the presence of pentobarbital were attenuated by a subsequent inhibition of CAo. 3. Blockade of gamma-aminobutyric acid-A (GABAA) receptors with picrotoxin (PiTX; 100 microM) resulted in an enhancement of alkaline transients in s. pyramidale evoked by low-frequency stimulation (10 Hz) but suppressed alkaline shifts evoked by brief high-frequency (1 s, 100 Hz) trains of stimuli. 4. Application of trains of stimuli consisting of a constant number of pulses (50 or 100) revealed a striking dependence of the effect of benzolamide on stimulation frequency (10-200 Hz) in s. pyramidale: the enhancement of the alkaloses seen upon inhibition of CAo became progressively smaller with an increase in frequency, and at 100-200 Hz benzolamide produced a suppression or a complete block of the alkaline transients. However, alkaline transients evoked with the use of a constant train duration (5 s) were enhanced by benzolamide at all stimulation frequencies examined (5-200 Hz).(ABSTRACT TRUNCATED AT 250 WORDS)

Alkalies↗
PubMed1995

A new approach to control central deafferentation pain: spinal intrathecal baclofen.

Baclofen, an agonist of the gamma-aminobutyric acid (GABA) receptor, has antinociceptive effects, and its intrathecal administration reduces allodynic responses in animal models of neurogenic central pain. Such experimental studies lead to the hypothesis that neurogenic pain may be induced in part by functional abnormalities in spinal GABAergic systems. However, whether a GABAergic system is actually involved in human central pain is unknown. The authors investigated the effect of an intrathecal bolus injection of baclofen in 14 patients with central pain due to a stroke or spinal cord injury. Nine reported substantial pain relief they had never experienced previously. The effect appeared 1-2 h after the injection and persisted for 10-24 h. Allodynia and hyperalgesia, if present, were relieved as well. Pinprick and light touch sensations did not change in nonaffected regions. The results indicate that dysfunction of spinal GABAergic systems plays a role in the clinical expression of central pain. In clinical situations, continuous intrathecal infusion of baclofen seems feasible for relief of central pain.

Afferent Pathways↗
PubMed1995

Molecular and genetic dissection of a reproductive isolation gene, zygotic hybrid rescue, of Drosophila melanogaster.

Hybrids from the cross between males of Drosophila melanogaster and females of its sibling species (D. simulans, D. mauritiana, or D. sechellia) are embryonic lethal when they carry the wild type allele of zygotic hybrid rescue (zhr) from D. melanogaster. The zhr gene has been mapped in the proximal region of the X heterochromatin slightly distal to the proximal breakpoint of In(1)sc8, the region rich in 1.688 g/cm3 satellite DNA. Since this satellite DNA does not exist in the sibling species, the satellite DNA was considered to be involved in the hybrid lethality. We examined the hypothesis molecular cytogenetically. The results are (1) three Df(1)zhr chromosomes carried this satellite DNA, and (2) hybrids were viable even if the amount of the satellite DNA in hybrids was increased by adding minichromosomes Dp(1;f)1205 and Dp(1;f)1187 into the genome. These results do not support the above hypothesis.

Alleles↗
PubMed1995

A new method for in vitro calcification using acrylamide gel and bovine serum.

To investigate the mechanism of biological calcification in vitro, a model system consisting of an acrylamide gel block (1 x 3 x 3 mm) and fetal bovine serum was developed. Mineral deposition was induced in gel blocks which were immersed in 300 microliters of fetal bovine serum at 37 degrees C for 7 days in a CO2 incubator. X-ray diffraction indicated that the mineral was hydroxyapatite with low crystallinity. Effects of the concentration of acrylamide gel, the partial pressure of CO2 and matrix proteins within the gel on the mineral formation were investigated. In the gel concentration range of 10-60%, the largest amount of crystal grew in 40% acrylamide gel, where the serum protein did not penetrate. With an increase in the partial pressure of CO2 the Ca content in the gel block increased, reached the highest level at about 3.5% CO2 and then began to decrease. In 40% gel and at 5% CO2, the mineral formation was enhanced by phosvitin, phosphophoryn, demineralized dentin powder and alkaline phosphatase. Mineral deposition occurred around the collagen fibers immobilized in 40% acrylamide gel. These results indicate that 1) a putatively serum-derived inhibitor of calcification with high-molecular weight was prevented from penetrating into the 40% acrylamide gels, 2) immobilized polyanionic proteins and alkaline phosphatase were able to increase mineral deposition and 3) the partial pressure of CO2 greatly influenced the mineral deposition. It was concluded that this gel system is useful to investigate the mechanism of biological calcification in vitro.

Acrylamides↗