Biomedical subjects

H Kiyama

Publications and source records attributed to H Kiyama.

At least 91 records · Page 5Linked to original sources

PubMed1996

Accelerated Nerve Regeneration in Mice by upregulated expression of interleukin (IL) 6 and IL-6 receptor after trauma.

In this study we aimed to examine a role for interleukin 6 (IL-6) and its receptor (IL-6R) in peripheral nerve regeneration in vivo. We first observed that cultured mouse embryonic dorsal root ganglia exhibited dramatic neurite extension by simultaneous addition of IL-6 and soluble IL-6R (sIL-6R), a complex that is known to interact with and activate a signal transducing receptor component, gp130. After injury in the hypoglossal nerve in adult mice by ligation, immunoreactivity to IL-6 was upregulated in Schwann cells at the lesional site as well as in the cell bodies of hypoglossal neurons in the brain stem. In the latter, upregulation of the immunoreactivity to IL-6R was also observed. Regeneration of axotomized hypoglossal nerve in vivo was significantly retarded by the administration of anti-IL-6R antibody. Surprisingly, accelerated regeneration of the axotomized nerve was achieved in transgenic mice constitutively expressing both IL-6 and IL-6R, as compared with nontransgenic controls. These results suggest that the IL-6 signal may play an important role in nerve regeneration after trauma in vivo.

Animals↗

PubMed1996

Differential expression of oxytocin receptor mRNA in the developing rat brain.

The embryonic and postnatal localizations of oxytocin receptor mRNA in the developing rat brain were studied by in situ hybridization histochemistry. The hybridization signal was first detected at embryonic-day 13 in the primordium of the dorsal motor nucleus of vagus. Other positive regions progressively appeared after this time. The developmental profile of oxytocin receptor gene expression could be classified into two types; transient expression and constant abundant expression. The caudate putamen, cingulate cortex, the anterior thalamic nuclei, and the ventral tegmental area belonged to the first type. In these regions, oxytocin receptor mRNA was expressed intensely only during the early postnatal period. The regions such as the anterior olfactory nucleus, tenia tecta, some amygdaloid nuclei, piriform cortex, the ventromedial hypothalamic nucleus, subiculum, the prepositus hypoglossal nucleus and the dorsal motor nucleus of vagus showed constant expression of oxytocin receptor mRNA at high levels throughout development and in the adult. These findings concurred well with those of the ontogenic studies using receptor binding autoradiography with a ligand specific to oxytocin. Thus, the transient expression of oxytocin receptor during development was regulated at the transcriptional level in several brain regions, and oxytocin may play a role in brain development as well as in neural transmission in the mature brain.

Animals↗

PubMed1996

Cloning and characterization of the rat neurotensin receptor gene promoter.

The 5'-terminal region of the rat neurotensin receptor (NTR) gene was isolated and characterized. Genomic Southern analysis revealed that the NTR gene occurs as a single copy in the rat haploid genome. The upstream putative promoter region did not contain canonical TATA or CAAT boxes but has a consensus sequence for the transcription factor Sp1. This promoter is embedded in a large G + C-rich domain with characteristics of an CpG island. Transfection experiments using neurotensin receptor-luciferase fusion genes demonstrated that the 5'-flanking sequence functions as a strong promoter in the NG-108-15 cell. Deletion analysis suggested the presence of a core promoter (-470 to -662) that drives the minimal expression of the NTR gene.

Animals↗

PubMed1996

A stress-sensitive chemokinergic neuronal pathway in the hypothalamo-pituitary system.

Recently we found that cytokine-induced neutrophil chemoattractant influenced anterior pituitary hormone release in vitro. These observations prompted us to investigate the possibility of the existence of cytokine-induced neutrophil chemoattractant in the hypothalamus. Immunohistochemistry showed that cytokine-induced neutrophil chemoattractant-like immunoreactivity existed in the paraventricular hypothalamic nucleus, the supraoptic nucleus, both the internal and the external layers of the median eminence and the posterior pituitary. Since the paraventricular hypothalamic nucleus plays a pivotal role in response to stressful stimuli, we examined the effect of a single episode of immobilization stress on cytokine-induced neutrophil chemoattractant messenger RNA expression in the paraventricular hypothalamic nucleus. Immobilization stress induced strong hybridization signals of cytokine-induced neutrophil chemoattractant messenger RNA in the parvocellular and magnocellular subdivision of the paraventricular hypothalamic nucleus within 15 min, and cytokine-induced neutrophil chemoattractant-like immunostaining intensity in the posterior pituitary started to increase around the periphery of the posterior lobe at 30 min after stress and extended to the whole lobe at 1 h after stress. The increase in the serum cytokine-induced neutrophil chemoattractant in response to stress showed a kinetically biphasic pattern. A first phase occurred within 15 min which may be due to an immediate release of stored cytokine-induced neutrophil chemoattractant in the neurohypophysis, since hypophysectomy completely blocked this phase. A second phase may reflect the release of newly synthesized cytokine-induced neutrophil chemoattractant in the paraventricular hypothalamic nucleus and/or peripheral cytokine-induced neutrophil chemoattractant, since hypophysectomy could not reduce this phase. These data suggest that cytokine-induced neutrophil chemoattractant in the paraventricular hypothalamic nucleus was immediately synthesized in response to stress, and then released into the peripheral blood via the hypothalamo-neurohypophysial system, revealing the presence of a stress-sensitive chemokinergic neuronal pathway in the hypothalamo-pituitary system.

Animals↗

PubMed1996

Distinct localization of two serine-threonine kinase receptors for activin and TGF-beta in the rat brain and down-regulation of type I activin receptor during peripheral nerve regeneration.

The localizations of serine-threonine kinase receptor mRNA for the novel type I TGF-beta and/or activin receptor named B1 (rat), ALK-4 (mouse) or ActR-IB (human) were demonstrated by in situ hybridization. As the putative ligand for this receptor in the brain has not yet been clearly determined, we compared its localization to type II activin receptor (ActR-II) which is the counterpart of the type I activin receptor. B1 mRNA was widely observed in neuronal cells throughout the brain, and especially strong positive signals were found in the cerebral cortex, olfactory tubercle, and hippocampus. The localization of B1 mRNA coincided well with that of ActR-II. This strongly suggests that B1 (ALK-4/ActR-IB) could be the type I activin receptor, as type I and type II activin receptor were supposed to form a receptor complex. In addition, we examined the localization of type II TGF-beta receptor (TbetaRII) mRNA which is an essential counterpart of the type I TGF-beta receptors for TGF-beta signaling. TbetaRII mRNA was expressed mainly in non-neuronal cells such as choroid plexus. In addition, TbetaRII mRNA expression was also found in a minor population of neuronal cells. TbetaRII mRNA-positive neurons were observed in the reticular thalamus, laterodorsal tegmental nucleus, pedunculopontine tegmental nucleus and the ventral tegmental nucleus. The localization of TbetaRII was markedly different from that of activin receptors in the rat brain. Since TGF-betas and activins are known as growth factors and/or survival factors, we examined changes in levels of B1 and TbetaRII mRNA expression during peripheral nerve regeneration. Expression of B1 mRNA in the axotomized hypoglossal motoneurons was substantially decreased from day 3 after axotomy and this decrease was significant until postoperative day 28, whereas no TbetaRII signal was observed in hypoglossal nucleus prior or after axotomy. This transient down-regulation of B1 mRNA expression suggests that activin signaling is somehow suppressed during peripheral nerve regeneration.

Activin Receptors↗

PubMed1996

Molecular cloning of the rat NADH:ubiquinone oxidoreductase subunit and its up-regulation in the facial muscle after denervation: detected by means of differential display.

The differential display method was applied to identify gene expression which is especially up-regulated in the rat denervated skeletal muscle. Total RNA from normal and denervated facial muscles was isolated, amplified by PCR using certain primers, and separated by electrophoresis on polyacrylamide gel. PCR products which were apparently higher in the operated than in the control side were cut out from the gel and subsequently sequenced. One of the cDNA fragments obtained in the present study showed about 80% identity in nucleotide sequence and about 84% identity in amino acid sequence to one of the NADH: ubiquinone oxidoreductase (complex I) subunits from the bovine heart mitochondria (813). Complex I, the first and largest enzyme of the mitochondrial respiratory chain, transfers electrons from NADH to ubiquinone-10 (UQ-10). B13 is a 13 kDa subunit; deficiency of which causes incomplete or incorrect assembly of a functional complex I, resulting in one of the types of human mitochondrial myopathy. Northern blot analysis and in situ hybridization histochemistry confirmed that rat B13 mRNA expression was up-regulated after denervation and was distributed throughout whole muscle cell body. These findings suggest that up-regulation of the rat B13 mRNA expression after denervation plays an important role in the effective electron transfer from NADH to UQ-10 in skeletal muscle cells, resulting in restriction of lipid peroxidation and biological tissue damage.

Amino Acid Sequence↗

PubMed1996

Characteristic localization of gp130 (the signal-transducing receptor component used in common for IL-6/IL-11/CNTF/LIF/OSM) in the rat brain.

The localization of gp130, the signal transducing receptor component used in common for interleukin (IL)-6, IL-11, ciliary neurotrophic factor (CNTF), LIF and OSM, in the rat brain was demonstrated by immunohistochemistry using an antibody specific to gp130. The gp130 immunoreactivity was observed in both glial and neuronal cells. Two distinct neuronal staining patterns were observed. The first showed neuropil staining, observed mainly in telencephalic structures including the hippocampus, cerebral cortex and caudate-putamen. The second pattern was observed on the cytoplasmic membrane of neuronal somata and was found primarily in the lower brainstem, in the large neurons of the reticular formation, and in spinal and cranial motor neurons. Electron-microscopic analysis revealed that both types of gp130 immunoreactivity were primarily associated with the cytoplasmic membrane and were not localized exactly at synaptic sites. Further, gp130 immunoreactivity was also observed in the oligodendrocytes and subependymal zone. These widespread but characteristic patterns of gp130 immunoreactivity overlap well with those of IL-6 receptor and CNTF alpha chains, suggesting a role of cytokines and growth factors such as IL-6 and CNTF via gp130 in certain specific regions of the brain.

Amino Acid Sequence↗

PubMed1996

Endotoxin activates a chemokinergic neuronal pathway in the hypothalamo-pituitary system.

Cytokines play a critical role in the cascade of events that cause septic shok. One regulatory system suggested to be important in controlling inflammatory response is the neuroendocrine axis. One of the chemokines is cytokine induced neutrophil chemoattractant (CINC), which was first described as an immuno-modulator of peripheral tissue in inflammatory responses. To assess further the contribution of the chemokine to the central nervous system, we performed immunohistochemistry on rat brains and found strong CINC-like immunoreactivity in the posterior pituitary gland. Treatment with bacterial endotoxin (lipopolysaccharide; LPS) markedly enhanced CINC-like immunoreactivity in the posterior pituitary. Before the LPS challenge, signal for CINC mRNA was undetectable in the paraventricular hypothalamic nucleus (PVN). The LPS challenge induced strong hybridization signals of CINC mRNA in the parvocellular and magnocellular subdivision of the PVN within 15 minutes (min) and peaked at 30 min. The LPS challenge provoked no observable change in the supraoptic nucleus. These studies demonstrate the presence of an endotoxin-sensitive chemokinergic neuronal pathway in the hypothalamo-neurohypophysial system and this newly-described pathway will provide a novel information to understand another possible neuralimmune mechanism.

Animals↗

PubMed1996

[Recent molecular histochemistry and its application from localization to gene hunting].

In situ hybridization histochemistry is established as a method in molecular histochemistry. Although various methods were initially examined, the variation tends to converge into a few popular methods. Current methods in in situ hybridization histochemistry are introduced in this review. In addition, future aspects in the field of molecular histochemistry are discussed. A visualization of DNA binding molecules and an imaging of various phenomena in living tissue would substantially expand the potentiality of histochemistry. Furthermore, a molecular histochemical technique could be used, not only for a localization of molecule but also for a molecular biological method, such as, a screening process in the differential display, which is a sophisticated method, to hunt a specific gene. These advanced methods in molecular histochemistry could be quite useful in the field of thoracic diseases.

Animals↗

PubMed1996

[Application of extracorporeal membrane oxygenation for respiratory failure following septic pulmonary emboli].

A 23-year-old man, diagnosed as ventricular septal defect in childhood, was hospitalized with right-sided infective endocarditis. He developed acute respiratory failure following septic pulmonary emboli and underwent urgent surgical treatment, because vigorous medical treatment was ineffective. Extracorporeal membrane oxygenation was performed to maintain arterial blood oxygen tension after cardiopulmonary bypass and the patient was weaned from ECMO after 36 hours. Postoperatively, mechanical ventilation for respiratory failure was needed continuously and pleural leaks due to lung injuries were increased. The reduction of pleural leaks by surgical closure of fistula and plication of the cyst decreased gas exchange impairment. To our knowledge, application of extracorporeal membrane oxygenation for septic pulmonary emboli is unprecedented.

Adult↗

PubMed1996

[A case of primary anterior mediastinal liposarcoma with a heterotopic mass in the pericardium of the same histology].

We experienced a case of primary anterior mediastinal liposarcoma with a heterotopic mass in the pericardium of same histology. Twenty reported cases in Japan were also studied. The patient was a 50-year-old male who visited the hospital because of an abnormal shadow on a chest X-ray. The diagnosis of anterior mediastinal tumor was confirmed by a chest CT. The patient underwent a complete resection of the mediastinal and intrapericardial masses. The histologic diagnosis was a well differentiated liposarcoma of Enzinger's classification. No evidence of recurrence or metastasis was detected in the third postoperative year. Liposarcoma is rarely seen in the mediastinum. Since radiotherapy and chemotherapy are ineffective therapeutic modalities, surgery would be the treatment of choice and complete surgical resection is mandatory.

Heart Neoplasms↗

PubMed1995

Effects of MK801 on Fos expression in the rat brainstem after unilateral labyrinthectomy.

Unilateral labyrinthectomy (UL) causes ocular and postural asymmetries, which disappear over time in the processes of equilibrium recovery known as vestibular compensation. It has been reported that N-methyl-D-aspartate (NMDA) receptors are involved in vestibular compensation. In the present study, in order to elucidate the NMDA receptor-mediated neural circuit responsible for the development of vestibular compensation, we used Fos expression as a marker of neural activation and examined the effects of MK801, a specific antagonist of NMDA receptors, on UL-induced Fos expression in the rat brainstem. After UL, Fos-like immunoreactive (-LIR) neurons were observed in the ipsilateral medial vestibular nucleus (ipsi-MVe), the contralateral prepositus hypoglossal nucleus (contra-PrH) and the contralateral inferior olive beta subnucleus (contra-IOb). Fos-LIR neurons gradually disappeared in the processes of vestibular compensation. It is suggested that the activation of the ipsi-MVe, the contra-PrH and the contra-IOb neurons after UL are the initial event of vestibular compensation. Intraperitoneal injection of MK801 in the processes of vestibular compensation caused reappearance of UL-induced behavioral deficits. During the decompensation induced by MK801, Fos-LIR neurons appeared in the contra-MVe, the ipsi-PrH and the bilateral-IOB. It is suggested that the contra-MVe, the ipsi-PrH and the bilateral-IOb neurons are inhibited by glutamatergic synapses driving inhibitory neurons via NMDA receptors in the processes of vestibular compensation and that disinhibition of these nuclei induced by MK801 causes decompensation. However, MK801 caused neither Fos expression nor behavioral decompensation after vestibular compensation is accomplished. All these findings that the NMDA receptor-mediated inhibitory modulation in the central vestibular system plays an important role for the initial processes of the development of vestibular compensation.

Amino Acid Sequence↗

PubMed1995

A novel ATP-dependent inward rectifier potassium channel expressed predominantly in glial cells.

We have isolated a novel inward rectifier K+ channel predominantly expressed in glial cells of the central nervous system. Its amino acid sequence exhibited 53% identity with ROMK1 and approximately 40% identity with other inward rectifier K+ channels. Xenopus oocytes injected with cRNA derived from this clone expressed a K+ current, which showed classical inward rectifier K+ channel characteristics. Intracellular Mg.ATP was required to sustain channel activity in excised membrane patches, which is consistent with a Walker type-A ATP-binding domain on this clone. We designate this new clone as KAB-2 (the second type of inward rectifying K+ channel with an ATP-binding domain). In situ hybridization showed KAB-2 mRNA to be expressed predominantly in glial cells of the cerebellum and forebrain. This is the first description of the cloning of a glial cell inward rectifier potassium channel, which may be responsible for K+ buffering action of glial cells in the brain.

Adenosine Triphosphate↗

PubMed1995

Up-regulation of PKA RI alpha subunit mRNA in rat skeletal muscle after nerve injury.

Localization of all subunits of cAMP dependent protein kinase (PKA) mRNAs and their changes of expression after denervation were examined in rat tongue skeletal muscle by in situ hybridization histochemistry. Among all PKA subunits only RI alpha subunit mRNA was detected in the skeletal muscle, whereas positive signal of all subunits mRNA were observed in some haematocytes or lymphocytes within the tongue tissue. The RI alpha mRNA was distributed in a restricted area near the endplate. The mRNA level was substantially induced by the hypoglossal nerve transection, suggesting that the up-regulation of RI alpha mRNA leading to the down-regulation of PKA activity may contribute to some intracellular signalling modulation or to muscle specific gene transcription after the denervation.

Acetylcholinesterase↗

PubMed1995

Expression of glutamate (AMPA type) and gamma-aminobutyric acid (GABA)A receptors in the rat caudal trigeminal spinal nucleus.

The localization of GABAA receptor gamma 1 and gamma 2 subunits and the AMPA-type glutamate receptor subunits GluR1 and GluR2/3 were identified in the caudal trigeminal spinal tract nucleus (TNC) by immunohistochemistry using specific antibodies. The receptor species on the projecting neurons to the thalamus in TNC were also examined. A retrograde tracer, Fluoro-gold (FG), was injected into the thalamus, and the sections were simultaneously labeled with the antibodies. Injection of FG into the ventral posteromedial nucleus of the thalamus resulted in labeling of scattered neurons contralaterally in the TNC. Most of the neurons labeled by retrograde tracing also showed gamma 1- and gamma 2-like immunoreactivity, while many of the neurons containing FG lacked GluR1- and GluR2/3-like immunoreactivity. These findings show that neurons projecting to the thalamus from the TNC receive GABAergic input via GABAA receptors containing gamma 1 and gamma 2 subunits, while many neurons expressing the AMPA-type receptor did not project to the thalamus.

Animals↗

PubMed1995

Up-regulation of ferritin heavy chain mRNA expression in the rat skeletal muscle after denervation: detected by means of differential display.

The differential display method was applied to identify gene expression, which is especially up-regulated in denervated skeletal muscle. Total RNA from normal and denervated rat facial muscles (muscles zygomaticus, levator nasolabialis and caninus) was isolated, amplified by polymerase chain reaction (PCR) using certain primers and separated by electrophoresis on a polyacrylamide gel. PCR products, the amounts of which were significantly higher in the operated side than in the control side, were cut out from the gel and sequenced. One of the cDNA fragments obtained in the present study showed 100% identity in nucleotide sequence to the rat ferritin heavy chain (FHC) mRNA. Northern blot analysis and in situ hybridization histochemistry confirmed that FHC mRNA expression was up-regulated after denervation and was distributed throughout whole muscle cell bodies. The biological damage attributed to superoxide and hydrogen peroxide is dependent on the presence of intracellular free iron. Intracellularly, most of the iron that is not metabolized is sequestered in ferritin as a crystalline core of ferric irons (Fe3+). These findings suggest that alterations in the ferritin subunit composition after denervation play an important role in iron metabolism in skeletal muscle cells, resulting in restriction of the biological tissue damage caused by reactive oxygen species.

Animals↗

PubMed1995

Regulation of mRNA expression involved in Ras and PKA signal pathways during rat hypoglossal nerve regeneration.

Using in situ hybridization histochemistry and immunohistochemistry, the present study examines the cooperative regulation of transcription of molecules involved in the Ras-signal and the cAMP dependent protein kinase (PKA) pathways during peripheral nerve regeneration in rats. Injury to hypoglossal motor neurons resulted in an increase in extracellular regulated kinase (ERK, or MAP kinase) and ERK kinase (MEK, or MAP kinase kinase) mRNAs, but in a decrease in the expression of the catalytic subunits of PKA (C alpha and C beta) mRNAs. These results show the importance of the Ras-signal pathway in the nerve regeneration process and extend recent observation which suggested a cross-talk between the Ras and PKA pathways in vitro. The down-regulation of PKA may facilitate the activation of the Ras pathway which is located downstream of the growth factor receptor. The present study may suggest a possibility of regulatory talk between these two major signal transduction pathways.

Animals↗

PubMed1995

Differential expression of Notch1 and Notch2 in developing and adult mouse brain.

The Notch gene encodes a large transmembrane protein, and is required for the correct differentiation of both neural and non-neural tissues in Drosophila. Mammals have more than one Notch gene homolog, e.g. Notch1 and Notch2. Here, in order to determine the role of Notch genes in the mouse nervous system, we used in situ hybridization to study the expression of the Notch1 and -2 genes through mouse embryogenesis and into adulthood. The expression of Notch1 and Notch2 differed throughout development. Notch2 was expressed in the embryonic ventricular zone, the postnatal ependymal cells, and the choroid plexus throughout embryonic and postnatal development. Notch1 was also expressed in the ventricular zone between embryonic days 10 and 14, but its expression decreased gradually as embryos developed. The postnatal mouse brain strongly expressed Notch2, but not Notch1, in the granular cell layer of hippocampal dentate gyrus, where neurogenesis continues even in adult rodents. The most remarkable finding was the detection of a strong signal for Notch2 mRNA in two circumventricular organs: the subfornical organ and the area postrema. The receptor encoded by the Notch2 gene, which is located in these areas, may respond to unknown ligands in CSF. This putative receptor may participate in signal transduction by way of both neural and humoral links. These data suggest that Notch2, rather than Notch1, is related not only to development, but also to some postnatal functions of mouse central nervous system.

Animals↗