Grafted swine neuroepithelial stem cells can form myelinated axons and both efferent and afferent synapses with xenogeneic rat neurons

Neuroepithelial stem cells derived from the swine mesencephalic neural tube were examined regarding their eligibility for neural xenografting as a donor material, with the aim of evaluating myelinated axon formation and both types of synaptic formation with xenogeneic host neurons as part of possible neural circuit reconstruction. The mesencephalic neural tube tissues were dissected out from swine embryos at embryonic days 17 and 18 and were implanted immediately into the striatum of the Parkinsonian model rat. The swine-derived grafts had many nestin-positive rosette-forming, neurofilament-positive, and tyrosine hydroxylase-positive cells in the rat striatum. Electron microscopic study revealed both efferent and afferent synaptic formations in the donor-derived immature neurons or tyrosine hydroxylase-positive donor cells in the grafts. Myelinated axons, both positive and negative for swine-specific neurofilament antibody, were mingled together in the graft. These results indicated that implanted neuroepithelial stem cells could survive well and divide asymmetrically into both nestin-expressing precursors and differentiated neurochemical marker-expressing neurons in the xenogeneic rat striatum, with the help of an immunosuppressant. Donor-derived immature neurons formed both efferent and afferent synapses with xenogeneic host neurons, and donor-derived axons were myelinated, which suggests that implanted swine neuroepithelial stem cells could possibly restore damaged neuronal circuitry in the diseased brain.

Effect of intra-ischemic hypothermia on the expression of c-Fos and c-Jun, and DNA binding activity of AP-1 after focal cerebral ischemia in rat brain

It is unknown whether immediate early gene (IEG) induction and subsequent late gene regulation after ischemia is beneficial or deleterious. The aim of this study was to examine the effect of hypothermia on expression of c-Fos and c-Jun, and AP-1 DNA binding activity, after transient focal cerebral ischemia in rat brain, and clarify the role of IEGs and AP-1 after insults. Male Wistar rats underwent right middle cerebral artery occlusion for 1 h with the intraluminal suture method. During ischemia, animals were assigned to either normothermic (NT) or hypothermic (HT) groups. In the NT group, brain temperature was observed to spontaneously increase to 40 degrees C during ischemia. In the HT group, brain temperature decreased to 30 degrees C. Infarct volume in cortex was decreased in the HT group, compared with that in the NT group (P<0.001). Increased c-Fos immunoreactivity in the cortex was observed at 3 h after reperfusion in the HT, but not the NT group, while c-Jun expression was not affected by HT treatment. There was also a significant increase in AP-1 DNA binding activity at 3 h in the HT group when compared to the NT group (P<0.01). In conclusion, hypothermia decreased cerebral infarction in association with early increases in c-Fos expression and AP-1 DNA binding activity in peri-infarct cortex. It remains to be established whether such responses are a cause or consequence of cell survival, but these results clearly establish that altered transcription is a key feature of tissue spared following hypothermic focal ischemia.

Functional recovery after simultaneous transplantation with neuro-epithelial stem cells and adjacent mesenchymal tissues into infarcted rat brain

BACKGROUND

Cerebral infarction results in impairment of motor and cognitive functions. We performed intracranial transplantation of multipotential neuro-epithelial stem cells with mesenchyme into experimentally large ischemic lesions to study their potential to relieve deficits.

METHODS

Wistar albino rats were subjected to transient middle cerebral artery occlusion for 60 minutes, producing an extensive ischemic lesion in the ipsilateral striatum and adjacent cerebral cortex. The rat mesencephalic neural plate at the early somite stage (embryonic day 10.5) together with adjacent ventral mesenchyme was used as donor material. We performed histological and immunohistochemical studies, with antibodies against tyrosine hydroxylase, and dopamine- and adenosine 3': 5'-monophosphate-regulated phosphoprotein 32 (DARPP-32; a striatal marker). Micro-angiograms were made by using Microfil silicone rubber. Morris Water-maze learning and treadmill task were employed to evaluate motor and cognitive functions.

FINDINGS

A viable non-tumoral mass was recognized in the rat striatum, up to as long as 156 days after transplantation. There were many cells positive for tyrosine hydroxylase or DARPP-32 in the graft. Some of the DARPP-32 positive cells within the graft had extended their dendrites into host tissues. In the micro-angiograms, many fine vessels were observed within the graft and dilated vessels meandered around the graft. Transplanted animals recovered significantly better in motor and cognitive functions than animals injected with only culture medium.

INTERPRETATION

Neuro-epithelial stem cells may follow several lines of differentiation; along the naturally genetically programmed line of differentiation, or along other cell lines depending on different environments. Grafting of neuro-epithelial stem cells with mesenchyme may merit a further study as a treatment for cerebral infarction.

Postischemic hypothermia inhibits the generation of hydroxyl radical following transient forebrain ischemia in rats

A small reduction of body temperature during reperfusion following cerebral ischemia has been known to ameliorate neuronal injury. However, the mechanisms underlying postischemic hypothermia-induced neuroprotection are poorly understood. The burst of reactive oxygen species (ROS) formation that occurs during reperfusion has been documented to be involved in ischemic neuronal degeneration. In this study, we investigated the effect of postischemic hypothermia on ROS production following transient forebrain ischemia using an in vivo microdialysis technique. Forebrain ischemia was induced by bilateral carotid artery occlusion combined with hemorrhagic hypotension for 20 min in male Wistar rats. The body temperature was kept at 37 degrees C during ischemia and controlled at either 32 degrees C or 37 degrees C after reperfusion. The amount of hydroxyl radical produced in striatum was evaluated by measurement of 2,3- and 2,5-dihydroxybenzoic acid (DHBA), which is generated by salicylate hydroxylation. We also measured the extracellular concentration of xanthine, while determining striatal blood flow by the hydrogen clearance technique. In animals whose postischemic body temperature was maintained at 37 degrees C, the levels of 2,3- and 2,5-DHBA significantly increased after reperfusion. The peak levels of 2,3- and 2,5- DHBA were 2.9-fold and 2.7-fold increased above the corresponding baseline values, respectively. Postischemic hypothermia completely inhibited the hydroxyl radical formation. Likewise, xanthine formation was also inhibited by postischemic hypothermia. In contrast, striatal cerebral blood flow was not altered by temperature modulation during reperfusion. These results suggest that inhibition of ROS production accompanied with suppression of xanthine formation is implicated in the neuroprotection of postischemic hypothermia.

Orbital malignant fibrous histiocytoma with extension to the base of the skull--case report

An 18-year-old woman presented with a malignant fibrous histiocytoma (MFH) originating in the orbit and invading the frontal and temporal base of the skull manifesting as exophthalmos and double vision that had persisted for 2 months. Magnetic resonance imaging revealed a tumor in the left orbit that extended as far as the frontal and temporal base of the skull. The tumor was treated by radical resection with conservation of the eyeball and its contents, followed by orbit wall reconstruction. The histological diagnosis was MFH. Local radiotherapy was administered postoperatively. The preoperative symptoms improved, and there has been no evidence of local recurrence or metastasis in the year since the surgery. In this case, radical resection of the tumor was essential. Furthermore, the adjuvant therapy was apparently successful, probably because this histological type of tumor is highly sensitive to radiotherapy.

Feasibility of using early mesencephalic neural plate for intracerebral grafting

The purpose of this study was to elucidate the biological significance and the possibility of intracerebral grafting of neuroepithelial stem cells derived from the mesencephalic neural plate. Immunohistological studies of embryonic day 10.5 (E10.5) Wister rats revealed strong nestin expression in the mesencephalic part of the neural plate. Mesencephalic neural plates removed from E10.5 rats were processed to either tissue or cell dissociation culture. They were cultured in vitro under various conditions and were analyzed 7 days after the primary culture. When they were cultured as a tissue, cell proliferation and differentiation into neurons extending long neurites were obvious in a serum-free medium, in a medium containing 3% serum, and in a medium containing 20 ng/ml epidermal growth factor. On the other hand, in a medium containing 10 ng/ml basic fibroblast growth factor (bFGF), both vigorous cell proliferation and sphere formation were recognized. Furthermore, marked neurite growth was rarely seen in this culture. When they were plated in a dissociation culture, cell proliferation and neurosphere generation were also recognized only in a medium containing bFGF, depending on the initial cell concentration. The spheres, generated 7 days after the primary cell culture, were positively stained by nestin. These data suggested that bFGF was able to amplify the stem cell population present in the mesencephalic neural plate derived from early embryos. This might make it possible to obtain a large number of stem cells as donor material for neural transplantation on demand.

Extensive and dense calcification in the core of a ventrally exophytic brainstem glioma

The first case of a ventrally exophytic pontine glioma with extensive and dense calcification is reported. A 10-year-old boy presented with a generalized seizure. The skull radiogram and CT scan showed a dense area of calcification, revealed by MRI as the core of a ventrally exophytic tumor. The pathologic diagnosis was fibrillary astrocytoma.

Patched and smoothened mRNA expression in human astrocytic tumors inversely correlates with histological malignancy

Patched (Ptc) is a transmembrane receptor for sonic hedgehog (Shh) and functionally associated with another transmembrane protein, smoothened (Smo). Ptc is a tumor suppressor gene whereas Smo serves as a proto-oncogene of neuroectodermal tumors. Their downstream molecules, Gli1, Gli2, and Gli3, are oncogenes of glioblastomas. We have analyzed mRNA expression of Ptc, Smo, and Gli family members in human astrocytic tumors. The mRNA expression was quantified by real-time polymerase chain reactions in 40 tumors (diffuse astrocytomas; 6 cases: anaplastic astrocytomas; 12 cases: glioblastomas; 22 cases) and four cell lines derived from astrocytic tumors. The MIB-1 proliferating cell indices (PCIs) of these tumors were analyzed by immunohistochemistry. In comparison with the World Health Organization (WHO) classification, the amount of Ptc and Smo mRNAs decreased in proportion to the progression of histological maliganancy, and similar results were obtained with astrocytic tumor-derived cell lines. However, there was no remarkable correlation between the mRNA expression level of each gene and the MIB-1 PCIs. The mRNA expression level of Gli1 was variable and highly elevated in two cases. No remarkable features were found clinically or histologically in these two cases. In summary, our results indicate that Ptc and Smo mRNA levels have an inverse correlation with histological malignancy and suggest that these gene products are implicated in the suppression of astrocytic tumors. In contrast, there was no significant correlation between the mRNA levels of the Gli family members and histological malignancy, suggesting that Gli proteins are not associated with the progression of astrocytic tumors.

Cytokines regulate c-Met expression in cultured astrocytes

We investigated c-Met expression in cultured astrocytes and their regulation by cytokines. Immunocytochemistry revealed that c-Met was expressed in cultured astrocytes. Western blotting revealed that acidic and basic fibroblast growth factor (FGF) enhanced and hepatocyte growth factor (HGF) reduced c-Met expression. Reverse transcription-polymerase chain reaction revealed that FGFs and HGF enhanced c-met expression. These findings suggest that c-Met expressed in astrocytes may have important roles during the nervous system regeneration.

Midterm results of conservative repair of the incompetent bicuspid aortic valve

AIM

Repair of the bicuspid aortic valve is not generally considered the treatment of choice. Our success with this procedure leads us to report our immediate and mid-term

RESULTS

METHODS

From August 1993 to December 2000, 19 patients with aortic regurgitation due to congenital aortic valve underwent aortic valve repair (17 men and 2 women with a mean age of 42+/-17 years; range, 16 to 70 years). The mean preoperative aortic regurgitation grade was 3.1+/-0.8 on a scale of 1 to 4. Mean preoperative New York Heart Association functional class was 1.9+/-0.8. Fourteen patients had pure aortic regurgitation, 2 also had infectious endocarditis, 1 had angina pectoris, and 2 had an ascending aortic aneurysm.

RESULTS

There was 1 hospital death (5.2%), and 1 patient required re-operation due to recurrent infectious endocarditis. Mean aortic regurgitation grade at discharge was 1.1+/-0.9, and functional class was 1.1+/-0.2. All patients were followed for a mean duration of 40+/-23 months (range, 0.5 to 84 months). There was 1 late death, and two patients required aortic valve replacement. The 5-year survival rate was 90+/-7%. The 1- and 5-year re-operation-free rates were 87+/-12% and 76+/-23%.

CONCLUSIONS

Bicuspid aortic valve repair is a safe procedure with good early postoperative

RESULTS

However midterm results are not satisfactory. Re-operation is a promising alternative and progress aortic regurgitation were complications. Bicuspid aortic valve repair to valve replacement that requires additional study to individualize treatment.

[Aortic valve repair with minimal access "J" sternotomy]

Recently many cardiovascular operations have been performed with minimally invasive cardiac surgery (MICS). It is reported that MICS is superior to standard full sternotomy in regard to cosmetic and post-operative recovery. In our institution, aortic valve repair operations have been performed to aortic valve insufficiency. This time, we performed aortic valve repair by minimal access "J" sternotomy. A 63-year-old male with degenerative aortic regurgitation underwent aortic valve repair by MICS. He had experienced dyspnea on exertion 7 days before admission. Preoperative transthoracic echocardiogram showed the grade of aortic regurgitation (AR) was severe. Surgery was successful and the grade of AR became trivial. This combined procedure have merits for patients because of freedom from anticoagulation and small incision. Such combined surgery may be indicated in the treatment in a subset of patients with degenerative AR.

Suprasellar peri-infundibular ectopic prolactinoma--case report

A 21-year-old man presented with bitemporal hemianopia and hyperprolactinemia. Magnetic resonance (MR) imaging showed a suprasellar cystic tumor in contact with the pituitary stalk. The diagnosis was craniopharyngioma. Intraoperatively, there was no clear continuity between the tumor and the tissue of the anterior lobe of the pituitary gland. The pituitary stalk and the diaphragma sellae were intact, and their morphology remained almost completely normal after the tumor was removed. The histological diagnosis was prolactin-producing pituitary adenoma. Postoperatively, the bitemporal hemianopia improved, and the serum prolactin levels returned to normal. The final diagnosis was suprasellar ectopic pituitary adenoma arising in the peri-infundibular region. Follow-up MR imaging at 1 year showed a normal pituitary stalk and pituitary gland, with no evidence of residual tumor.

Gliofibrous nodule in the cerebello-medullary fissure

An extra-axial nodule in the cerebello-medullary fissure is described, occurring in a 27-year-old-woman. MRI and CT scans revealed the lesion was a non-enhanced round mass, which was associated with mild atrophy of the surrounding cerebellum, but with no perifocal edema. In the surgical observation, the mass was white, elastic and hard, well demarcated and localized in the cerebello-medullary fissure. Histologically, the lesion was composed of astrocytes and collagen-producing fibroblasts with no anaplasia. These findings suggested that the lesion was hamartomatous, but not neoplastic. This type of gliofibrous nodule has not been previously reported.

Ultrastructural analysis of the paranodal junction of myelinated fibers in 31-month-old-rats

Recent studies have revealed a significant decrease in white matter volume, including loss of myelin, with age but minimal decrease in gray matter volume (Guttmann et al., [1998] Neurology 50:972-978). Myelin is necessary for the rapid conduction of impulses along axons. Myelinated nerve includes various domains, the node of Ranvier, the paranodal region, the juxtaparanodal region and the internode. The paranodal junction may serve to anchor the myelin sheath to the axon. We analyzed the ultrastructure of the paranodal region in myelinated fibers from the aged rat brain. Severe alterations of myelinated fibers were observed in 31-month-old rats, resulting in the appearance of macrophages, splitting of the myelin sheath, myelin balloon formation and separation from the axon. Many paranodal retractions of myelinated axons occurred in the aged rats. It should be noted that the paranodal junction is functionally important, serving to anchor the myelin to the axon and that there is a diffusion barrier in the paranodal region. We analyzed myelin-related proteins from young and aged rat brains. The 21.5-kDa isoform of myelin basic protein (MBP) almost disappeared in the 31-month-old rats, whereas other myelin proteins were not significantly changed between young and aged rats. These results suggest that this isoform, a highly cationic charged major dense component protein that binds lipid bilayer in the membrane, may participate in the formation of a paranodal diffusion barrier at the myelin/noncompact membrane border.