Kyoji Sakai

Reduction of ischemic brain injury by topical application of insulin-like growth factor-I after transient middle cerebral artery occlusion in rats

In order to examine the effect of insulin-like growth factor-1 (IGF-1) on ischemic brain injury, IGF-1 was applied topically on the surface of reperfused rat brain after 60 min of transient middle cerebral artery occlusion (MCAO). In contrast to the cases treated with vehicle, the infarct area was greatly reduced at 24 h of reperfusion by treatment with IGF-1. Terminal deoxynucleotidyl transferase mediated dUTP-biotin in situ nick labeling (TUNEL) staining and immunoreactivity for glycogen synthase kinase 3beta (GSK3beta) were also markedly reduced in the brains with IGF-1 treatment. The present results suggest that the treatment with IGF-1 significantly ameliorates brain injury after transient focal brain ischemia associated with the reduction of TUNEL and GSK3beta stainings.

Protective effect of ginkgo extract on rat brain with transient middle cerebral artery occlusion.

Abstract It has been empirically known that Ginkgo extract is useful for reducing many symptoms associated with cerebral blood flow (CBF) insufficiency, but its mechanisms have been uncertain. In the present study, therefore, we gave Ginkgo extract to rats with per os digestion, and investigated its effect on CBF and ischemic brain damage with middle cerebral artery occlusion (MCAO). The treatment with Ginkgo extract (W mg 100g-1 rat) increased CBF in the normal condition, but the degree of increase in CBF was lesser during and after MCAO. TTC staining showed that infarct volume was reduced with Ginkgo treatment. TUNEL and HSP72 immunostaining confirmed the protective effect of Ginkgo treatment reducing numbers ofTUNEL and FiSP72 positive cells. Immunohistochemical analysis showed that caspase-3 expression was less abundant in Ginkgo treated rats. The present results suggest that Ginkgo extract contains a substance which increases normal CBF and reduces ischemic brain damage. [Neurol Res 2000; 22: 517-521]

The effect of a new immunosuppressive agent, FK-506, on xenogeneic neural transplantation in rodents

This study examines the effect of a novel immunosuppressive agent FK-506 (FK) on the survivability of embryonic (E14) rat ventral mesencephalic tissue after intracerebral grafting to the lateral ventricle of adult mice. The recipient mice were given FK in doses of 10 mg/kg or 1 mg/kg for 2 weeks postgrafting, at which time they were sacrificed and histologically processed except for one group of animals on the high dose (10 mg/kg). In this group most animals died from side effects of the drug during the following days. Only the mice receiving the high dose of FK displayed healthy grafts without signs of rejection.

Sjögren’s syndrome with acute transverse myelopathy as the initial manifestation

This is the first report of a patient with acute transverse myelopathy as the initial manifestation of primary Sjögrens syndrome (SS). The patient developed tetraparesis and sensory disturbance within 6 days of onset. Spinal MRI showed an extensive intraparenchymal lesion with high T2-weighted signal intensity, gadolinium enhancement, and cord swelling. Although the patient did not show clinical sicca symptoms, primary SS was diagnosed on the basis of clinical tests on lacrimal and salivary glands which showed high levels of autoantibodies. Treatment with prednisone improved motor and sensory symptoms and resulted in improvement of MRI findings. The present case suggests that acute transverse myelopathy can occur as an initial symptom of SS.

Phosphorylation of retinoblastoma protein in rat brain after transient middle cerebral artery occlusion

Although mature neurones do not replicate genomic DNA, some cell cycle‐related kinases are aberrantly activated in neurones after ischaemia. As hyper‐phosphorylation of retinoblastoma (Rb) protein is the common pathway in mitotic signal cascade, this study investigated the phosphorylation state of the Rb protein as well as its mRNA level in rat brain after transient middle cerebral artery (MCA) occlusion. Immunohisto‐chemical analysis revealed that neurones in the sham‐operated brain expressed Rb protein without the hyperphosphorylated form. Immunoreactivity for the hyperphosphorylated form of Rb protein progressively increased from 1 h to 3 days after ischaemia in neurones in the MCA territory. Western blot analysis demonstrated a similar change. However, reverse transcription‐polymerase chain reaction study revealed that Rb showed no definite change at the mRNA level. These results suggest that Rb protein is progressively hyper‐phosphorylated in the brain after ischaemia, which may activate apoptotic mechanisms in neuronal cells of the brain after ischaemia.

Topical application of neurotrophin-3 attenuates ischemic brain injury after transient middle cerebral artery occlusion in rats

In order to examine the effect of neurotrophin-3 (NT-3) on ischemic brain injury, NT-3 was topically applied to brain surface just after 90 min of middle cerebral artery occlusion (MCAO) in rats. NT-3 significantly reduced the infarct size at 24 h of reperfusion. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick labeling (TUNEL) staining and immunohistochemical study for caspase-3 and heat shock protein 72 (HSP72) showed that NT-3 treatment decreased the number of cells with DNA fragmentation and caspase-3 and HSP72 expressions. These data suggest that NT-3 protects neuronal cells from ischemic injury, and it is possibly associated with inhibition of DNA fragmentation.

Suppression of immunorejection against rat fetal dopaminergic neurons in a mouse brain by 15-deoxyspergualin

In this study, the immunosuppressive effect of 15-deoxyspergualin (DSG) on the survivability of rat embryonic dopaminergic neurons grafted into the lateral ventricle of adult mice was investigated. DSG was administered daily in dose of 5 mg/kg for 2 weeks postgrafting, commencing on the day of transplantation, in the immunosuppressant-treated groups. Animals were then allowed to survive for 2 to 4 weeks after transplantation. Histological analysis revealed that most of transplanted rat fetal neural tissue was destroyed and scavenged in 2 weeks after transplantation in the non-immunosuppressed group. However, a large number of tyrosine hydroxylase (TH)-positive grafted neurons survived and grew postgrafting in the brain of the host administered with DSG even if they suffered from T lymphocyte infiltrations visualized by cytotoxic T cell immunohistochemistry. The results thus indicated that DSG is an potent immunosuppressant in neural transplantation as well as in transplantation of other organs in animals. It seems to be able to block, at least in part, the ability of mature specific cytotoxic T cells to lyse their targets.

Infarct presenting with a combination of Wallenberg and posterior spinal artery syndromes

This is the first report of a patient presenting with a combination of Wallenberg and posterior spinal artery syndromes. The patient developed right hemiplegia and sensory disturbances on the right side of the face and over the whole body. MRI showed infarcts of the cerebellum, medulla oblongata, and upper cervical cord. These lesions were in the territory of the right posterior inferior cerebellar artery (PICA) and the right posterior spinal artery (PSA). The combination was due to severe stenosis of the right vertebral artery.

Clonic perseveration in the subacute stage of Japanese encephalitis

We report a very rare case of Japanese encephalitis (JE) presenting with reversible stereotyped movement in the subacute stage. A 58-year-old woman presented with high fever, headache, nausea, vomiting, and consciousness disturbance. Cranial magnetic resonance imaging (MRI) of fluid attenuated inversion recovery (FLAIR) and T2-weighted image (WI) showed high intensity areas in the bilateral thalamus, caudate nucleus and hippocampus. She developed coma, convulsion, and ballism in the acute stage. One month after onset, she showed rhythmic, stereotyped, repetitive movements with hypoperfusion in the thalamus and frontal cortex on single photon emission computed tomography (SPECT). Three months later, her stereotyped movement improved accompanied by recovery of hypoperfusion in the thalamus and frontal cortex on SPECT. We speculated that her stereotyped movement was clonic perseveration due to frontal dysfunction induced by thalamofrontal disconnection.

Reduction of tyrosine kinase B and tyrosine kinase C inductions by treatment with neurotrophin-3 after transient middle cerebral artery occlusion in rat.

Infarct volume and immunoreactivities for trkB and trkC in rat brain were compared at 24 h after 90 min of transient middle cerebral artery occlusion (MCAO) between animal groups with or without neurotrophin-3 (NT-3, 10 microg/250 g animal). Treatment of rat brain with topical application of NT-3 significantly reduced infarct volume (P = 0.02) and trkB and trkC inductions. These data suggest that NT-3 reduced the ischemic injury along with the reduction of trkB and trkC inductions.