Ki-Bum Sim

Temporal patterns of the embryonic intermediate filaments nestin and vimentin expression in the cerebral cortex of adult rats after cryoinjury

The expression of two embryonic intermediate filaments, nestin and vimentin, in the rat brain at days 0 (control), 1, 4, 7 and 14 post-cryoinjury was studied to elucidate their roles in brain injury. Western blot analysis showed that both nestin and vimentin expressions in the ipsilateral cerebral cortex were significantly increased at 4 and 7 days post-cryoinjury, and were decreased at day 14 after cryoinjury. Immunohistochemistry showed that there were few nestin- and vimentin-positive cells in the cerebral cortex in normal controls. On days 4 and 7 post-injury, abundant glial cells in the periphery of the lesion were immunostained for nestin and/or vimentin; only vimentin was detected in the majority of inflammatory cells in the core lesion. These findings suggest that nestin and vimentin contribute to the repair of brain injury through the migration of activated cells and the formation of a glial scar.

Temporal expression of osteopontin and CD44 in rat brains with experimental cryolesions

Expression of osteopontin and CD44 in the brain was studied after cryolesioning to understand how osteopontin and its receptor, CD44, are involved in processes in the brains of rats with cryolesions. Western blot analysis showed that osteopontin increased significantly at days 4 and 7 post-injury and declined slightly thereafter in cryolesioned brains in comparison with levels in sham-operated controls. An immunohistochemical study localized osteopontin in activated microglia/macrophages in the core lesions, where the majority of macrophages proliferate. Osteopontin was also detected temporarily in some neurons and a few astrocytes in the lesion periphery on days 4 and 7 post-injury, but the immunoreactivity in macrophages, neurons, and astrocytes disappeared by day 14 post-injury. There was some CD44, a receptor for osteopontin, in the brain cells of sham-operated rats. After injury, intense CD44 immunostaining was seen in the majority of macrophages and in reactive astrocytes, but not in neurons, in the ipsilateral lesions after day 4 post-injury, and this immunoreactivity remained on day 14 post-injury. These findings suggest that activated microglia/macrophages and some neurons are major sources of osteopontin during the early stage of brain damage induced by a cryolesion and that osteopontin interacts with CD44 expressed on astrocytes and activated microglia/macrophages in the damaged cerebral cortex, possibly mediating cell migration after cryolesioning in the rat brain.

Upregulation of phospholipase D1 in the spinal cords of rats with clip compression injury

This study examined phospholipase D 1 (PLD1) expression in the central nervous system following clip compression spinal cord injury (SCI) in Sprague-Dawley rats. After inducing SCI with a vascular clip, the expression of PLD1 in the affected spinal cord was analyzed by Western blot and immunohistochemistry. Western blot analysis showed that the expression of PLD1 gradually increased in the spinal cord on days 0.5, 1, 2, and 4 post injury. Immunohistochemistry showed that some cells, including neurons, astrocytes, and some inflammatory cells, were positive for PLD1 in the lesions at days 1 and 2 post injury. At day 4, the number of PLD1-positive cells in SCI lesions increased, largely matching the increases in ED1-positive macrophages and glial fibrillary acidic protein-positive astrocytes. At this time, macrophages expressed proliferating cell nuclear antigen in addition to PLD1. These results suggest that PLD1 expression is increased in injured spinal cords, and might be involved in the activation and proliferation of macrophages and astrocytes in SCI.

Immunohistochemical study of arginase-1 in the spinal cords of rats with clip compression injury.

The expression of arginases, enzymes that catalyze the hydrolysis of arginine to ornithine and urea, was studied in the inflammatory lesions of spinal cord injury (SCI) in rats. The level of arginase-1 expression in rat spinal cords with clip compression injury was determined by Western blot analysis and immunohistochemistry. Western blot showed that the level of arginase-1 increased in the core lesion of SCI at day 1 post injury and continued to increase through days 4 (p<0.05) and 7 (p<0.01). Immunohistochemical analysis showed that arginase-1 was constitutively expressed in neurons and glial cells in sham control spinal cords. In SCI lesions, arginase-1 was additionally detected in inflammatory cells, particularly in isolectin B4-positive macrophages and reactive astrocytes within the core lesion. These findings suggest that the increased level of arginase-1 in SCI is associated with an increase in macrophages and reactive astrocytes, possibly contributing to the modulation of inflammation during the course of SCI.

Alternatively activated macrophages in spinal cord injury and remission: another mechanism for repair?

Tissues within the central nervous system (CNS) have generally been regarded as immunologically privileged. However, in recent decades, it has been shown that immune reactions in the CNS continuously occur via various types of inflammation following autoimmune diseases and mechanical insults such as spinal cord injury (SCI). Among the various inflammatory cells associated with CNS disease, activated macrophages are classically known to induce detrimental consequences that are mediated by the secretion of pro-inflammatory molecules. Alternatively activated macrophages have recently been shown to modulate various types of CNS inflammation, including SCI. This review summarizes the potential roles of alternatively activated macrophages in the course of CNS inflammation in rodent SCI models.

Upregulation of CD44 expression in the spinal cords of rats with clip compression injury.

The expression of the extracellular matrix phosphoglycoprotein CD44 after compression injury of the spinal cord was examined in rats. Western blot analysis of tissues harvested on days 0 (sham), 1, 4 and 7 post-injury showed significant increases in CD44 expression from 1 to 7 days after compression injury compared to sham-operated controls. Immunohistochemistry revealed that CD44 was constitutively expressed in some astrocytes in sham-operated controls. At days 4-7 post-injury, CD44 was intensely expressed in astrocytes in the periphery of lesions, and in myelin sheaths, vessels, and the majority of inflammatory cells including macrophages in core lesions. The finding that expression of CD44 was upregulated after spinal cord injury suggests that CD44 contributes to cell adhesion and glial cell attraction during the early stages after spinal cord injury, and may thus promote remodeling of injured spinal cords.

Cerebellar pilocytic astrocytoma presenting with intratumor bleeding, subarachnoid hemorrhage, and subdural hematoma.

IntroductionMassive intracranial hemorrhage is a very rare initial presentation of cerebellar pilocytic astrocytomas. There are no reports in the medical literature on a cerebellar pilocytic astrocytoma presenting with intratumor bleeding (ITB), subarachnoid hemorrhage (SAH), and subdural hematoma (SDH).Case reportA 15-month-old boy presented with lethargy and nausea to our hospital. Magnetic resonance imaging showed a mass with ITB at the left cerebellar hemisphere in addition to SDH in the posterior fossa and SAH at the interpeduncular cistern. The patient underwent emergency surgery. On incising the dura, we found SDH, the tumor was visible at the cerebellar cortex, and near total removal followed. Microscopic examination of tissue sections revealed a pilocytic astrocytoma.DiscussionThe authors’ case is the first report with a presentation including ITB, SAH, and SDH. The presumed mechanism of the SAH and SDH was leaking of the ITB into subarachnoid and subdural spaces.

Morphological study of surgically induced open neural tube defect in old (14 and 21 days) chick embryos

As an experimental model for the research of open neural tube defect (NTD), the surgical model has several advantages over others, in spite of the fact that the pathogenetic mechanism is not compatible with the human intrauterine events. To make reproducible NTDs by surgery and to compare the surgically induced lesions with the human myeloschisis morphologically, we opened the neural tube for a length of 9-11 somites in Hamburger and Hamilton stage 16-19 chick embryos. Embryos which survived until the late in ovo life (total age 14 and 21 days) showed relatively reproducible open NTDs. Morphologically they are similar to human myeloschisis. This study suggests that the surgical model can be suitable for studies of open NTDs.

Sodium salicylate-induced amelioration of experimental autoimmune encephalomyelitis in Lewis rats is associated with the suppression of inducible nitric oxide synthase and cyclooxygenases.

We studied the effects of oral administration of sodium salicylate on the expression of the pro-inflammatory mediators, nitric oxide synthase (iNOS) and cyclooxygenase- (COX-) 1 and 2, in rats with experimental autoimmune encephalomyelitis (EAE). Sodium salicylate (200 mg/kg) was administered orally for 13 days after the induction of EAE by immunization with guinea pig myelin basic protein and complete Freunds adjuvant. The onset (P<0.0001) and severity (P<0.05) of EAE paralysis in salicylate-treated animals were delayed and suppressed significantly compared with vehicle-treated controls. Western blot analysis showed that expression of COX-2 and iNOS, but not COX-1, decreased significantly in the spinal cords of salicylate-treated rats compared with vehicle-treated controls (P<0.05) and this finding was paralleled by immunohistochemical observations. These results suggest that the amelioration by salicylate of paralysis in rats with EAE is mediated in part by the suppression of COX and iNOS.

Potential role of fibronectin in microglia/macrophage activation following cryoinjury in the rat brain: An immunohistochemical study☆

To investigate whether fibronectin, a high-molecular weight glycoprotein of the extracellular matrix (ECM), plays a role in the activation of microglia/macrophages after brain injury, we examined the changes in fibronectin and arginase-1, a marker for alternatively activated macrophages, in a rat cryoinjury model using Western blot analysis, real-time reverse transcription PCR and immunohistochemistry. The protein and mRNA level of fibronectin and arginase-1 significantly increased in the injury site of the ipsilateral cerebral cortex at days 4 and 7 after cryoinjury but was decreased at day 14. The immunohistochemical analysis revealed fibronectin expression in ED1-positive microglia/macrophages and reactive astrocytes, in the lesion core and periphery, respectively. Fibronectin immunoreactivity in the lesion was similar to arginase-1 except that fibronectin was detected in the ECM after cryoinjury. The present results suggest that fibronectin was extravasated into injured brain lesions via an impaired blood-brain barrier and stimulated glial cells including microglia and infiltrating macrophages in the lesion core and periphery to become alternatively activated microglia/macrophages, which modulated CNS inflammation after brain injury.