Biomedical subjects

Isao Nagano

Publications and source records attributed to Isao Nagano.

At least 19 recordsLinked to original sources

PubMed2006

Intrathecal injection of epidermal growth factor and fibroblast growth factor 2 promotes proliferation of neural precursor cells in the spinal cords of mice with mutant human SOD1 gene.

We investigated three steps of neural precursor cell activation--proliferation, migration, and differentiation--in amyotrophic lateral sclerosis spinal cord treated with intrathecal infusion of epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2) into the lumbar spinal cord region of normal and symptomatic transgenic (Tg) mice with a mutant human Cu/Zn superoxide dismutase (SOD1) gene. We observed that 5-bromodeoxyuridine (BrdU) + nestin double-labeled neural precursor cells increased in the spinal cords of Tg mice compared with non-Tg mice, with a much greater increase produced by EGF and FGF2 treatment. The number of BrdU + nestin double-labeled cells was larger than that of BrdU + ionized calcium-binding adapter molecule-1 (Iba1), BrdU + glial fibrillary acidic protein (GFAP), or BrdU + highly polysialylated neural cell adhesion molecule (PSA-NCAM) double-labeled cells, but none expressed neuronal nuclear antigen (NeuN). On further analysis of the gray matter of Tg mice, the number of BrdU + nestin and BrdU + PSA-NCAM double-labeled cells increased more in the ventral horns than the dorsal horns, which was again greatly enhanced by EGF and FGF2 treatment. Because neural precursor cells reside close to the ependyma of central canal, the present study suggests that proliferation and migration of neural precursor cells to the ventral horns is greatly activated in symptomatic Tg mice and is further enhanced by EGF and FGF2 treatment and, furthermore, that the neural precursor cells preferentially differentiate into neuronal precursor cells instead of astrocytes in Tg mice with EGF and FGF2 treatment.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Temporal profile of neural stem cell proliferation in the subventricular zone after ischemia/hypoxia in the neonatal rat brain.

OBJECTIVES: Ischemia/hypoxia (I/H) causes severe neonatal brain injury, such as periventricular leukomaracia and hypoxic/ischemic encephalopathy. Neural stem cell research could lead to a treatment for such disorders. In order to elucidate the dynamic changes in neural stem cells in the neonatal brain after I/H, we investigated the proliferation of new cells in the subventricular zone (SVZ). METHODS: Seven-day-old Wister rats were subjected to ligation of the left carotid artery followed by 2 hours of hypoxic stress (8% O(2) and 92% N(2), at 33 degrees C). In order to elucidate the dynamic change of neural stem cells in the SVZ, single bromodeoxyuridine (BrdU; 50 mg/kg) was administered 2 hours before death 1, 7, 14 and 21 days after I/H. Immunohistochemical and immunofluorescent studies for BrdU and doublecortin (DCX) were carried out. As a control, a group of rats was subjected to sham surgery (incision of skin, but no ligation of the carotid artery) and no I/H. RESULTS: The numbers of BrdU-labeled cells in the SVZ, for both the ipsilateral side and the contralateral side of the I/H brain, were twice the level of the control at 7 days after I/H, but the numbers for both sides returned to the control level at 21 days. In the ipsilateral side of the I/H brain, the number of BrdU-labeled cells in the SVZb (lining the upper wall of lateral ventricle) was 4-fold at 7 days and 15-fold at 21 days after I/H compared with the control level. This chronological pattern is very similar to the pattern for I/H results of the posterior periventricle (pPV). DCX appeared in most BrdU-labeled cells in the SVZb and pPV. DISCUSSION: These findings indicate that I/H enhances neural stem cell proliferation in the SVZ, and some newborn cells migrate as neural precursors to the SVZb and pPV after I/H in the neonatal rat brain.

Animals↗

PubMed2005

Prevention of spinal motor neuron death by insulin-like growth factor-1 associating with the signal transduction systems in SODG93A transgenic mice.

The role of insulin-like growth factor-1 (IGF-1) in amyotrophic lateral sclerosis (ALS) and its mechanism of action are important from both pathogenic and therapeutic points of view. The present study investigated the changes of IGF-1Rbeta and the key intracellular downstream protein insulin receptor substrate-1 (IRS-1) by using SOD1(G93A) transgenic mice with continuous intrathecal IGF-1 treatment. The number of lumbar spinal motor neurons was preserved with IGF-1 treatment in a dose-dependent manner. The numbers of immunopositive motor neurons for IGF-1Rbeta and IRS-1 were not significantly different between wild-type and Tg mice with vehicle treatment, whereas treatment of Tg mice with IGF-1 decreased the numbers of immunopositive motor neurons in a dose-dependent manner. On the other hand, the ratio of immunopositive motor neurons per total living motor neurons in vehicle-treated mice was greatly increased in Tg mice with vehicle treatment compared with wild-type mice. With IGF-1 treatment, the ratio was dramatically decreased in a dose-dependent manner. These results suggest that IGF-1 treatment prevents motor neuron loss by affecting the signal transduction system through IGF-1R and the main downstream signal, IRS-1.

Analysis of Variance↗

PubMed2005

Therapeutic benefit of intrathecal injection of insulin-like growth factor-1 in a mouse model of Amyotrophic Lateral Sclerosis.

Insulin-like growth factor (IGF)-1 has been shown to have a protective effect on motor neurons both in vitro and in vivo, but has limited efficacy in patients with amyotrophic lateral sclerosis (ALS) when given subcutaneously. To examine the possible effectiveness of IGF-1 in a mouse model of familial ALS, transgenic mice expressing human Cu/Zn superoxide dismutase (SOD1) with a G93A mutation were treated by continuous IGF-1 delivery into the intrathecal space of the lumbar spinal cord. We found that the intrathecal administration of IGF-1 improved motor performance, delayed the onset of clinical disease, and extended survival in the G93A transgenic mice. Furthermore, it increased the expression of phosphorylated Akt and ERK in spinal motor neurons, and partially prevented motor neuron loss in these mice. Taken together, the results suggest that direct administration of IGF-1 into the intrathecal space may have a therapeutic benefit for ALS.

Age Factors↗

PubMed2005

The protective effect of dantrolene on ischemic neuronal cell death is associated with reduced expression of endoplasmic reticulum stress markers.

The endoplasmic reticulum (ER) plays an important role in ischemic neuronal cell death. In order to determine the effect of dantrolene, a ryanodine receptor antagonist, on ER stress response and ischemic brain injury, we investigated changes in ER stress-related molecules, that is phosphorylated form of double-stranded RNA-activated protein kinase (PKR)-like ER kinase (p-PERK), phosphorylated form of eukaryotic initiation factor 2alpha (p-eIF2alpha), activating transcription factor-4 (ATF-4), and C/EBP-homologous protein (CHOP), as well as terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) in the peri-ischemic area and ischemic core region of rat brain after transient middle cerebral artery occlusion (MCAO). In contrast to the cases treated with vehicle, the infarct volume and TUNEL-positive cells were significantly reduced at 24 h of reperfusion by treatment with dantrolene. The immunoreactivities for p-PERK, p-eIF2alpha, ATF-4, and CHOP were increased at the ischemic peripheral region after MCAO, which were partially inhibited by dantrolene treatment. The present results suggest that dantrolene significantly decreased infarct volume and provided neuroprotective effect on rats after transient MCAO by reducing ER stress-mediated apoptotic signal pathway activation in the ischemic area.

Activating Transcription Factor 4↗

PubMed2005

Up-regulation of low-density lipoprotein receptor expression in the ischemic core and the peri-ischemic area after transient MCA occlusion in rats.

Low-density lipoprotein (LDL) receptor is involved in cholesterol metabolism of CNS as a receptor of apolipoprotein E (ApoE), which plays an important role in regenerative process after brain ischemia. Temporal and spatial changes of LDL receptor were investigated after 90 min of transient middle cerebral artery occlusion (MCAO) in relation to those of microtubule-associated protein 2 (MAP2) and ApoE. In the ischemic core, LDL receptor became positive at 1 d after transient MCAO, which was not double positive for MAP2 or ApoE, and disappeared in 7 and 56 d. In the peri-ischemic area, LDL receptor became observed at 7 d, which peaked at 21 d, most of which were double positive for MAP2. The number of LDL receptor and ApoE double-positive cells increased at 7 d and decreased at 21 d with the shift of LDL receptor immunoreactivity from cytoplasm at 7 d to dendrites at 21 d in the peri-ischemic area. These results suggest that LDL receptor, interacting with ApoE, is profoundly involved in lipid transport of CNS for tissue repair in the peri-ischemic area after brain ischemia.

Animals↗

PubMed2005

Neural precursor cells division and migration in neonatal rat brain after ischemic/hypoxic injury.

Ischemia/hypoxia (I/H) causes severe perinatal brain disorders such as cerebral palsy. The neonatal brain possesses much plasticity, and to enhance new cell production would be an innovative means of therapy for such disorders. In order to elucidate the dynamic changes of neural progenitor cells in the neonatal brain after ischemia, we investigated new cells production in the subventricular zone and subsequent migration of these cells to the injured area. Newly produced cells were confirmed by incorporation of bromodeoxyuridine (BrdU), and attempt for differentiation was investigated by immunohistochemistry for molecular markers of each cellular lineage. In the sham-control brain, there were many BrdU-labeled cells which gradually decreased as the animal becomes older. Many of these cells were oligodendroglial progenitor or microglial cells. Although there were only few neuronal cells labeled for BrdU in the sham-control, they dramatically increased after I/H. They were located at just beneath the subventricular zone where the progenitor cells reside and to the injured area, indicating that newly produced cells migrated to the infarct region and differentiated into neuronal precursor cells in order to compensate the lost neural cells. We found that BrdU-labeled astroglial, oligodendroglial progenitor, and microglial cells were also increased after I/H, suggesting that they also play active roles in recovery. Progenitor cells may have potential for treating perinatal brain disorders.

Animals↗

PubMed2005

Expression of neurocan after transient middle cerebral artery occlusion in adult rat brain.

Neurocan is one of the major chondroitin sulfate proteoglycans in the nervous tissues. The expression and proteolytic cleavage of neurocan are developmentally regulated in the normal rat brain, and the full-length neurocan is detected in juvenile brains but not in normal adult brains. Recently, some studies showed that the full-length neurocan was detectable even in the adult brain when it was exposed to mechanical incision or epileptic stimulation. In the present study, we demonstrated by Western blot analysis that the full-length neurocan transiently appeared in the peri-ischemic region of transient middle cerebral artery occlusion (tMCAO) in adult rat with a peak level at 4 days after tMCAO. Immunohistochemical analysis showed that a clear positive signal of neurocan was observed 4 days after tMCAO in the peri-ischemic region of cerebral cortex and caudate, where cells strongly positive in GFAP expression were also distributed. These results indicate that accumulation of the full-length neurocan produced by reactive astrocytes may be one of the processes for tissue repair and reconstruction of neural networks after focal brain ischemia as well.

Animals↗

PubMed2005

HMG CoA reductase inhibitors reduce ischemic brain injury of Wistar rats through decreasing oxidative stress on neurons.

Statins possess neuroprotective effect against ischemic damage, but how they protect neurons is not exactly made clear. We speculated that anti-oxidative property of statins is implicated, and investigated statins' influences on the oxidative neuronal damage in the brain after ischemia. After 14 days of atorvastatin, pitavastatin, simvastatin, or vehicle administration, 90 min of middle cerebral artery occlusion was imposed on Wistar rats. The production of 4-hydroxynonenal (HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), both of which are oxidative stress markers, as well as infarction formation were investigated at 1 day after the reperfusion. In the vehicle group, massive infarction was confirmed and HNE and 8-OHdG are robustly produced. In the statins-treated group, the infarction was smaller and the HNE and 8-OHdG production was less prominent than the vehicle group. Among the statins investigated, simvastatin was most effective for reducing oxidative stress and infarction volume, which may be brought by its highly lipophilic property. Reduction of oxidative stress by statins may be one main reason in ameliorating ischemic brain damage in rats.

Aldehydes↗

PubMed2005

Reduction of cerebral infarction in stroke-prone spontaneously hypertensive rats by statins associated with amelioration of oxidative stress.

BACKGROUND AND PURPOSE: This study aimed to clarify the effect of statins on spontaneous stroke and to examine the antioxidative effect in artificial transient middle cerebral artery occlusion (tMCAO). METHODS: Stroke-prone spontaneous hypertensive rats (SHR-SP) were treated with pitavastatin, atorvastatin, simvastatin, or vehicle for 4 weeks. Physiological parameters, serum lipids, and infarct volumes were examined. The markers for oxidative stresses on lipids and DNA were immunohistochemically detected in vehicle-treated or simvastatin-treated SHR-SP with tMCAO. RESULTS: Atorvastatin and simvastatin decreased infarct volumes, with simvastatin most effective. Simvastatin significantly reduced immunoreactivities for oxidative stress markers for lipids and DNA in neurons after tMCAO. CONCLUSIONS: The results suggest that the antioxidative properties of statins may be implicated in their beneficial effects against neuronal damage in cerebral ischemia.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2005

Limited differentiation to neurons and astroglia from neural stem cells in the cortex and striatum after ischemia/hypoxia in the neonatal rat brain.

OBJECTIVE: We examined whether progenitor neural stem cells can differentiate successfully into mature neurons and astrocytes in a rat model of neonatal hypoxic-ischemic encephalopathy. STUDY DESIGN: Seven-day-old Wistar rats were subjected to hypoxic-ischemic stress. At days 5 to 7 after hypoxic-ischemic stress, 5-bromodeoxyuridine (an early marker of cell proliferation) was injected, and the brains were retrieved at 14, 28, and 42 days after hypoxic-ischemic stress. Immunohistochemical and immunofluorescent studies were carried out for 5-bromodeoxyuridine, neuronal nuclear antigen (a marker protein of matured neuron), and glial fibrillary acidic protein (a protein marker of mature astrocytes). RESULTS: Only 1% of neuronal nuclear antigen-positive and 4.6% of glial fibrillary acidic protein-positive cells could be detected among the 5-bromodeoxyuridine-immunopositive cells in the peri-infarcted area of the cortex and the striatum, respectively, at 14 days after hypoxic-ischemic stress. There were no such double-staining cells at 28 and 42 days after hypoxic-ischemic stress. CONCLUSION: The intrinsic ability for neurologic self-repair was limited at the maturation step after hypoxic-ischemic stress in the neonatal rat brain.

Animals↗

PubMed2005

Deficiency of PAR-2 gene increases acute focal ischemic brain injury.

The expression profile of the protease-activated receptor-2 (PAR-2) and effects of PAR-2 gene knockout (PAR-2 KO) on the infarct size were investigated after 60 minutes of transient middle cerebral artery occlusion (tMCAO) in mice in relation to phosphorylated extracellular signal-regulated kinase (p-ERK) and astrocyte activation. PAR-2 was normally distributed mainly in neurons of the central nervous system (CNS), and strongly upregulated at 8-24 hours after tMCAO. Deficiency of PAR-2 gene significantly increased the infarct volume and the number of TUNEL-positive cells at 24 hours of reperfusion. The strong neuronal expression of p-ERK was induced at 5 minutes as a peak after reperfusion in wild-type mice, but the signal change was significantly reduced in PAR-2 KO mice. Astroglial activation was also greatly inhibited at 24 hours after tMCAO in PAR-2 KO mice. These results show that the deficiency of PAR-2 gene increases the acute ischemic cerebral injury associating with suppression of neuronal ERK activation and reactive astroglial activation.

Animals↗

PubMed2005

Beneficial effects of intrathecal IGF-1 administration in patients with amyotrophic lateral sclerosis.

OBJECTIVES: There is currently no effective pharmacological treatment for amyotrophic lateral sclerosis (ALS). In a transgenic mouse model of ALS, intrathecal infusion of insulin-like growth factor (IGF)-1 showed a promising increase in survival. We performed a double-blind clinical trial to assess the effect of intrathecal administration of IGF-1 on disease progression in patients with ALS. METHODS: Nine patients with ALS were randomly assigned to receive either a high dose (3 microg/kg of body weight) or low dose (0.5 microg/kg of body weight) of IGF-1 every 2 weeks for 40 weeks. The outcome measurements were the rate of decline of bulbar and limb functions (Norris scales) and forced vital capacity. RESULTS: The high-dose treatment slowed a decline of motor functions of the ALS patients in total Norris and limb Norris scales, but not in bulbar Norris or vital capacity. The intrathecal administration of IGF-1 had a modest but significant beneficial effect in ALS patients without any serious adverse effects. DISCUSSION: Intrathecal IGF-1 treatment could provide an effective choice for ALS although further studies in more patients are needed to confirm its efficacy and optimize dosages of IGF-1.

Dose-Response Relationship, Drug↗

PubMed2005

Unique cerebellar-cerebral form of autosomal recessive ataxia.

We describe a unique condition affecting two siblings with a form of progressive spinocerebellar ataxia. After a period of very slowly progressive ataxia, the patients developed an extremely accelerated progression of the condition which consisted of cerebellar ataxia, seizure, progressive dementia and spastic tetraparesis. Age of onset was variable at 7 to 18 years. Brain magnetic resonance image (MRI) showed marked atrophy of the cerebellum and cerebrum with strikingly preserved brainstem dimensions. Biochemical or molecular genetic analysis was performed in an elder sister and her parents to exclude known forms of familial spinocerebellar ataxia, dentatorubral-pallidoluysian atrophy (DRPLA), progressive myoclonic epilepsy, and some metabolic disorders which could have a similar phenotype. The mode of inheritance appears to be autosomal recessive. We think that the affected siblings may have a new type of autosomal recessive cerebellar ataxia.

Adolescent↗

PubMed2005

[A case of corticobasal degeneration that progressed from primary progressive aphasia].

A 65-year-old woman began to experience slowly progressive speech disturbance from 2001. She was admitted to our hospital for examination on May 2003. She had dysprosody, paragraphia, and mild disturbance in comprehension of spoken language. Repetition was preserved. No clear paraphasia was found. Calculation was disturbed, but there were no other neurological abnormalities including apraxia and agnosia. Brain MRI showed atrophy of the left frontal and parietal lobes. 99mTc-ECD SPECT showed decreased blood flow in the left frontal lobe and parietal lobe, especially in the Broca area and supplemental motor cortex. Primary progressive aphasia was diagnosed, because aphasia lasted for 2 years without other neurological deficits, and her daily activity was well preserved. During follow up, facial apraxia appeared from December 2003, and limb apraxia appeared from May 2004, followed by rigidity predominantly in the right upper limb and dementia. She was diagnosed as having corticobasal degeneration (CBD). The second SPECT on December 2004 showed progression of the decrease in cerebral flow at the same area showed by the first SPECT. SPECT is useful examination to predict the progress of the disease because the decrease of blood flow was recognized before the progression to CBD.

Aged↗

PubMed2004

Nonparaneoplastic limbic encephalitis with relapsing polychondritis.

Relapsing polychondritis (RP), which shows pain, swelling and destruction of the affected parts, is a rare autoimmune disorder affecting cartilage. We report a patient with RP that affected skull cartilage, who subsequently developed multifocal meningoencephalitis. The patient presented with severe recent memory disturbance, anxiety and moderate depression. MRI study showed bilateral median temporal lobe lesions including hippocampi and amygdaloidal bodies, abnormal findings that disappeared after treatment with high-dose steroids. This is thought to be the first case of RP presenting amnesic syndrome and mental disorder associated with nonparaneoplastic limbic encephalitis involving bilateral hippocampi and amygdaloidal bodies detected by MRI.

Anxiety↗

PubMed2004

Protection against ischemic brain damage in rats by immunophilin ligand GPI-1046.

To determine the effect of immunophilin ligand GPI-1046 on ischemic brain injury, 90 min of transient middle cerebral artery occlusion (MCAO) was carried out in rat brains. In contrast to cases treated with vehicle, the infarct volume was reduced greatly and rotamase activity was inhibited significantly at 24 hr of reperfusion by treatment with GPI-1046. Immunoreactivity and the number of cells stained positively for FKBP12, FKBP52, caspase-8, cytochrome c, and caspase-3 were also reduced markedly in the brain after GPI-1046 treatment. The present results suggest that GPI-1046 significantly decreased infarct volume and provided neuroprotective effect on rats after transient focal cerebral ischemia by inhibiting the increase of rotamase activity and of the number of FKBP12-, FKBP52-, caspase-8-, cytochrome c-, and caspase-3-positive cells in the ischemic area.

Analysis of Variance↗

PubMed2004

Molecular cloning and characterisation of two kinds of proteins in excretory-secretory products of Trichinella pseudospiralis.

Two genes encoding Trichinella pseudospiralis excretory-secretory proteins related to the Trichinella spiralis glycoproteins were cloned and the excretory-secretory proteins were characterised. A cloned gene, designated Tp38 (Ts43), contained a cDNA transcript of 1035 bp, and the predicted amino acid sequence of the Tp38 (Ts43) pro-protein had a similarity of about 84% to that of the T. spiralis 43 kDa glycoprotein. A cloned gene, designated Tp53 (Ts53), contained a cDNA transcript of 1239 bp, and the predicted amino acid sequence of the Tp53 (Ts53) pro-protein had a similarity of about 68% to that of the T. spiralis 53 kDa glycoprotein. Southern blots indicated that the Tp38 (Ts43) and Tp53 (Ts53) genes were encoded in a single copy within the T. pseudospiralis genome. Western blots showed that T. pseudospiralis-infected sera recognised the Tp53 (Ts53) recombinant protein, but did not recognise the Tp38 (Ts43) recombinant protein. The Tp38 (Ts43) and Tp53 (Ts53) proteins in the excretory-secretory product were 3 and 9 kDa greater than the expected molecular mass, respectively, and had three isoforms with a similar molecular size. Reverse transcription polymerase chain reaction results showed that the production of the mRNA transcript for the Tp38 (Ts43) or Tp53 (Ts53) gene was restricted predominantly to muscle larvae. Western blots confirmed that the gene products were predominantly expressed by muscle-stage larvae. An immunolocalisation study showed the Tp38 (Ts43) and Tp53 (Ts53) proteins were present within the alpha-stichocyte and the beta-stichocyte of muscle larvae, respectively.

Amino Acid Sequence↗