Biomedical subjects

Junichi Hamada

Publications and source records attributed to Junichi Hamada.

11 recordsLinked to original sources

PubMed2006

Altered levels of serotonin in lymphoblasts derived from migraine patients.

We previously reported that dysfunctions in the autonomic nervous systems of patients with migraines occur not only in the brain, but throughout the whole body. Serotonin and neuropeptides are also known to have important roles in the pathophysiology of migraine. With this background in mind, we analyzed human lymphoblast cell lines from migraine with aura (MwA) patients to investigate the pathophysiology of migraine. The characteristics of these lymphoblasts and the involvement of the lymphoblasts in serotonin metabolism were examined. The lymphoblasts expressed serotonin receptors as well as some enzymes related to serotonin metabolism. The serotonin level in the MwA lymphoblasts was higher than that in the control cells. However, serotonin uptake into the lymphoblasts in MwA patients was similar to that in the control subjects. These findings suggest that lymphoblasts in MwA patients have altered levels of serotonin metabolism. Moreover, we propose that this lymphoblast cell system could serve as a novel modality for migraine research.

5-Hydroxytryptophan↗

PubMed2006

Plasma 5-hydroxytryptamine (5-HT) in migraine during an attack-free period.

OBJECTIVE: We measured the plasma 5-HT, 5-hydroxytryptophan (5-HTP), and tryptophan levels in controls, migraine patients with aura (MWA), and migraine patients without aura (MWoA) during an attack-free period. BACKGROUND: Serotonin (5-hydroxytryptamine, 5-HT) has been implicated in the pathophysiology of migraine. The precise relationship between 5-HT and migraine, however, remains unclear. METHODS: Blood samples in controls, MWA, and MWoA patients during an attack-free period were collected from brachial arteries and analyzed using HPLC. RESULTS: The plasma tryptophan and 5-HTP levels were not significantly different between the controls and migraine patients (either MWA or MWoA). However, the plasma 5-HT level in the MWA patients was significantly lower than that in the controls and MWoA patients. CONCLUSIONS: The present data suggest that reduced levels of 5-HT in MWA may result from either a dysfunction in the enzymes involved in serotonin biosynthesis or a dysfunction in 5-HT release or uptake from platelets and lymphocytes. These findings indicate the existence of a serotonin metabolism dysfunction in MWA patients that may differ from the state of serotonin metabolism in MWoA patients.

5-Hydroxytryptophan↗

PubMed2005

Nedd9 protein, a Cas-L homologue, is upregulated after transient global ischemia in rats: possible involvement of Nedd9 in the differentiation of neurons after ischemia.

BACKGROUND AND PURPOSE: Some proteins involved in self-repair after stroke in the adult brain are primarily expressed during embryonic development and strongly down-regulated during the early postnatal phase. Neuronal precursor cell-expressed, developmentally down-regulated gene (Nedd) 9 was recognized to be identical to Crk-associated substrate lymphocyte type (Cas-L), a docking protein that associates with a variety of signaling molecules, such as focal adhesion kinase (FAK), proline-rich tyrosine kinase 2 (Pyk2), and Crk. We investigated the involvement of these proteins in the pathophysiology of global cerebral ischemia. METHODS: The mouse Cas-L/Nedd9 cDNAs were cloned. The expression and function of Cas-L/Nedd9 protein in the pathogenesis of global ischemia in rats was investigated by RT-PCR, Western blot analysis, and immunohistochemistry. The neurite outgrowth of the transfectants of Nedd9 deletion mutants in PC-12 cells was also assessed to clarify the function of the Nedd9 protein. RESULTS: Nedd9 was a splicing variant of Cas-L and was selectively induced in neurons of the cerebral cortex and hippocampus 1 to 14 days after the ischemia. Induced Nedd9 protein was tyrosine phosphorylated and was bound to FAK in dendrite and soma of neurons after the ischemia. Finally, it was demonstrated that Nedd9 promoted neurite outgrowth of PC-12 cells. CONCLUSIONS: Our study may support the potential of Nedd9 for participation in the differentiation of neurons after global ischemia in rats.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Clinical and laboratory features of in-patients with multiple sclerosis in a University Hospital in Tokyo from 1988-2002.

OBJECTIVE: The aim of this study was to analyze the clinical and laboratory features of each subtype of multiple sclerosis (MS) (relapsing-remitting, primary progressive, and secondary progressive) in the Tokyo metropolitan area. METHODS AND PATIENTS: We retrospectively analyzed the medical records of 104 consecutive patients with a diagnosis of MS, who had been admitted to our university hospital from 1988 to 2002. They all met criteria for definite MS, by clinical or laboratory standards. RESULTS: Eighty-four (80.8%) patients were classified as having relapsing-remitting MS, while 8 patients (7.7%) and 12 patients (11.5%) were classified as having primary progressive MS and secondary progressive MS, respectively. A significant female predominance existed in the relapse-remitting MS (female : male=2.4 : 1) cohort, but this ratio was 1 : 1 in both primary progressive and secondary progressive MS. The age at onset was older in the primary progressive MS (36.6+/-17.1 years of old) population than in either the relapsing-remitting MS (27.9+/-11.1) or the secondary progressive MS (27.8+/-11.5) subjects. Although the duration of illness was similar among the three types of MS, the number of exacerbations in the secondary progressive (5.9+/-4.6) cohort was significantly higher than that in the relapsing-remitting MS subjects (3.2+/-2.6). Patients with primary progressive MS showed a significantly higher rate of gait disturbance (87.5%) as the initial symptom than those with relapsing-remitting MS (23.8%), and this was thought to be due to the higher incidence of brainstem and spinal cord lesions. Visual disturbance as the initial symptom was frequently noted in those with secondary progressive MS (50.0%), while it was noted only in 29.8% and 12.5% in the relapsing-remitting and primary progressive patients, respectively. Primary progressive MS subjects had a higher propensity to be wheelchair-bound (75.0%) than those suffering from relapsing-remitting MS (1.2%). Increased total protein in the cerebrospinal fluid (CSF) of the secondary progressive cohort was statistically significant compared to the relapsing-remitting cohort. The frequency of oligoclonal IgG bands was rather low in each type of MS (17.1-33.3%). Gadolinium enhancement of plaques on MRI was more frequently present in secondary progressive MS (66.7%) than in either relapsing-remitting MS (32.1%) or primary progressive MS (50.0%). Of note, the opticospinal form was found in only 16.3% of the total MS patients, a proportion less than that in previous reports from southern Japan. CONCLUSION: The present study confirms that while the clinical and laboratory features of the MS patients in the Tokyo metropolitan area are similar to those in Western countries in most regards, features such as proportionally fewer primary and secondary progressive MS patients as well as less oligoclonal IgG bands on CSF analysis are different from those in Western countries.

Adult↗

PubMed2005

[Medication-overuse headache].

Medication-overuse headache(MOH) is a clinically important entity and it is well documented that the regular use of acute symptomatic medication by patients with migraine or tension type headache increases the risk of aggravation of the primary headache disorders. MOH is one of the most common causes of chronic refractory headache. The pathophysiological mechanism of MOH is still unclear. But as in most of the headache entities, several different aspects, such as genetic background, peripheral and central nervous system interaction, specific psychotropic effects, appear to play key roles. Management of MOH is a difficult problem. The education for patients with MOH is very important.

Analgesics↗

PubMed2004

FK506 abrogates delayed neuronal death via suppression of nitric oxide production in rats.

BACKGROUND AND PURPOSE: The mechanism of the neuroprotective effect of FK506 in relation to nitric oxide (NO) production has not been clarified in vivo. We have investigated the effect of FK506 on ischemia-induced NO production in association with the pathogenesis of delayed neuronal death (DND) in rats. METHODS: In vivo microdialysis was performed in the hippocampus of male Sprague-Dawley rats (250-350 g). Dialysate samples were collected every 3 min. In the ischemia group (n=16), global ischemia was induced for 21 min and reperfusion was achieved. In the FK506 treatment group (n=25), FK506 (1 mg/kg, i.v.) was administered 21 min prior to the onset of global ischemia. Sham operations were done (n=15). The levels of NO(2)(-) in the dialysate samples were determined by the Griess reaction. The animals were decapitated 7 days after ischemia. Coronal brain sections were stained with hematoxylin and eosin. RESULTS: In the ischemia group, the NO(2)(-) level significantly increased during ischemia. In the FK506 treatment group, there was no significant change in the NO(2)(-) level during ischemia. In histological examinations, FK506 treatment showed a neuroprotective effect against DND. CONCLUSIONS: The effect of FK506 inhibiting NO production contributes to the neuro-protective effect of FK506 on DND in the hippocampus.

Analysis of Variance↗

PubMed2003

Induction of Tissue Factor Expression in Endothelial Cells by Basic Fibroblast Growth Factor and its Modulation by Fenofibric acid.

BACKGROUND: Tissue factor (TF), expressed in endothelial cells (ECs) and enriched in human atherosclerotic lesions, acts as a critical initiator of blood coagulation in acute coronary syndrome. Basic fibroblast growth factor (bFGF) induces the proliferation and migration of ECs and plays a role in angiogenesis and restoration of endothelial integrity. As TF is implicated in angiogenesis, we studied the effect of bFGF on TF gene and protein expression. Methods: Human umbilical vein ECs (HUVECs) were exposed to bFGF. TF mRNA was assessed by Northern blot and TF protein was assessed by Western blot. TF promoter activity was assessed by transient transfection assay and transcription factor was identified by electro mobility shift assay. RESULTS: bFGF increased TF mRNA and protein expression in HUVECs. Increased TF mRNA was attenuated by inhibition of extracellular signal-regulated kinase kinase in human ECV304 cells. Transient transfection assays of the human TF promoter-luciferase construct (-786/+121 bp) demonstrated that bFGF induced transcription was dependent on the elements within the -197 to -176 bp relative to the transcription start site of the human TF gene. This region contains NF-kappaB like binding site. Electro mobility shift assay showed that bFGF increased nuclear translocation or DNA binding of NF-kappaB transcription factor to TF promoter. Nucleotide substitution to disrupt NF-kappaB like site reduced bFGF stimulated promoter activity. Fenofibric acid, an agonist ligand for the peroxisome proliferator activated receptor-alpha, reduced basal and bFGF stimulated TF expression. CONCLUSIONS: These results indicate that bFGF may increase TF production in ECs through activation of transcription at NF-kappaB binding site, and control coagulation in vessel walls. Fibrate can inhibit TF expression and therefore reduce the thrombogenecity of human atherosclerotic lesions.

Journal Article↗

PubMed2003

Delayed phosphorylation of p38 mitogen-activated protein kinase in the AT1a knock-out mouse striatal neurons during middle cerebral artery occlusion and reperfusion.

To investigate whether the phosphorylation of p38 in cerebral ischemia occurs via angiotensin II receptor type 1a (AT1a), we examined the time course of phosphorylation of p38 and proline-rich tyrosine kinase 2 in AT1a knock-out mouse striatal neurons during middle cerebral artery occlusion (MCAO) and reperfusion. Phosphorylated-p38 was observed after 2 h and 5 h of reperfusion after 1 h of MCAO in C57/B6 mice and AT1a knock out mice, respectively. We demonstrated a delay of phosphorylation of p38 in the reperfusion model of the AT1a knock-out mouse, and detected microglia in the striatum on the ischemic side that were phosphorylated-p38-positive after 71 h of reperfusion in both animals. However, there was no association between AT1a and delayed neuronal cell death, or between AT1a and activation of caspase-9 in cerebral ischemia/reperfusion.

Animals↗

PubMed2002

Subcellular localization of a promoter and an inhibitor of apoptosis (Smac/DIABLO and XIAP) during brain ischemia/reperfusion.

We explored the expression of Smac/DIABLO, a newly identified mitochondrial apoptogenic molecule, and X-linked inhibitor of apoptosis protein (XIAP) in the brain subjected to ischemia/reperfusion. Transient focal ischemia was produced for 1 hour in mice. We observed only a negligible amount of Smac/DIABLO in both mitochondria and cytosol in the normal state. The mitochondrial expression level of Smac/DIABLO increased after 2-11 h reperfusion. There was increased Smac/DIABLO expression in the cytosol after 5 h reperfusion, implying the translocation of Smac/DIABLO into the cytosol. The subcellular localization of XIAP became more extensive within the cells during reperfusion, as compared with the normal state. Our results imply that Smac/DIABLO and XIAP are implicated in the pathophysiological mechanisms of reperfusion injury.

Animals↗

PubMed2002

Upregulation of Akt phosphorylation at the early stage of middle cerebral artery occlusion in mice.

Akt is a serine/threonine kinase that is believed to promote cell viability in many different cell types, including neurons. Here, we observed the state of Akt phosphorylation at several time points (1, 3, 6, 12, and 24 h) during permanent occlusion of the middle cerebral artery (MCA) in mice. We detected a transient upregulation of Akt phosphorylation at 1 h of MCA occlusion (MCAO) by Western blot analysis. Double immunostaining revealed that the enhanced phosphorylation of Akt occurred mainly in neurons located in the outer area of the MCA territory (ischemic penumbra). This phenomenon was accompanied by the nuclear translocation of Akt. We confirmed that Akt enzymatic activity is elevated in both the nuclear and cytosolic fractions of brain tissue subjected to 1 h of ischemia. cAMP-response-element-binding protein (CREB), an intranuclear target molecule of Akt, exhibited increased phosphorylation after 1 h of MCAO. In our ischemia model, caspase-3 was activated in the central part of the MCA territory as little as 1 h after MCAO. However, caspase-3 activation was not recognized at this time in the outer area of the MCA territory, where Akt activity was upregulated. These results suggest that prosurvival cell signaling is initiated in an active fashion before cell death pathways are activated in neurons situated in the ischemic penumbra at the early stage of ischemia.

Animals↗

PubMed2002

Temporal profiles of the subcellular localization of Bim, a BH3-only protein, during middle cerebral artery occlusion in mice.

BH3-only proteins are a subfamily of proapoptotic Bcl-2 proteins that act upstream of the mitochondrially mediated cell death pathway, and their association with the pathogenesis of brain ischemia remains largely unknown. The authors explored the temporal profiles of the expression levels and subcellular localization of BH3-only proteins in permanent middle cerebral artery occlusion (MCAO) by Western blot analysis. They observed an increased mitochondrial distribution of Bim at 3 to 6 hours of MCAO that appeared unrelated to transcriptional upregulation, as assessed by semiquantitative reverse transcription-polymerase chain reaction. At 3 to 6 hours of MCAO, Bim immunoreactivity was enhanced in neurons and oligodendrocytes in the ischemic regions. The increased mitochondrial localization of Bim coincided with a marked cytochrome c release and preceded the peak of caspase-9 activation. The authors observed an association of Bim with the dynein intermediate chain, a major component of the dynein motor complex, in the brain using a coimmunoprecipitation assay. Cerebral ischemia induced a time-dependent significant decrease in dynein expression, which started at 3 hours of MCAO. The authors deduced that the liberation of Bim from the dynein motor complex is a likely mechanism for the increased mitochondrial localization of Bim. During MCAO, Bad did not show any change in phosphorylation state or subcellular localization.

Animals↗