Recent studies have revealed that the adult mammalian brain has the capacity to regenerate some neurons after various insults. However, the precise mechanism of insult-induced neurogenesis has not been demonstrated. In the normal brain, GFAP-expressing cells in the subventricular zone (SVZ) of the lateral ventricles include a neurogenic cell population that gives rise to olfactory bulb neurons only. Herein, we report evidence that, after a stroke, these cells are capable of producing new neurons outside the olfactory bulbs. SVZ GFAP-expressing cells labeled by a cell-type-specific viral infection method were found to generate neuroblasts that migrated toward the injured striatum after middle cerebral artery occlusion. These neuroblasts in the striatum formed elongated chain-like cell aggregates similar to those in the normal SVZ, and these chains were observed to be closely associated with thin astrocytic processes and blood vessels. Finally, long-term tracing of the green fluorescent-labeled cells with a Cre-loxP system revealed that the SVZ-derived neuroblasts differentiated into mature neurons in the striatum, in which they expressed neuronal-specific nuclear protein and formed synapses with neighboring striatal cells. These results highlight the role of the SVZ in neuronal regeneration after a stroke and its potential as an important therapeutic target for various neurological disorders.

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Extradural subtemporal access to the petrosal ridge and a resection of the anterior pyramidal bone produced direct observation of the lower basilar artery, with minimum retraction of the temporal lobe and preservation of the temporal bridging veins. Two patients with lower basilar trunk aneurysms facing toward the brain stem, were operated on by the "transpetrosal approach," with successful clipping of the aneurysms. Auditory function was preserved in one case. This approach decreases the possibility of retraction damage to the temporal lobe, brain stem, or cranial nerves, and may be helpful for surgery of aneurysms arising around the vertebrobasilar junction or at the origin of the anterior inferior cerebellar artery.

ABSTRACT

This report presents a new surgical method and the results in 10 patients with petroclival meningiomas extending into the parasellar region (sphenopetroclival meningiomas). Minimal but effective extradural resection of the anterior petrous bone via a middle fossa craniotomy offered a direct view of the clival area with preservation of the temporal bridging veins and cochlear organs. The dural incision was extended anteriorly to Meckel's cave, and in cases with invasion of the cavernous sinus, Parkinson's triangle was enlarged by mobilization of the trigeminal nerve. This approach offered an excellent view from the mid-clivus to the cavernous sinus. Extra-as well as intradural tumor masses and dural attachments could be cleared under direct view of the pontine surface. The risk of injury to the lower cranial nerve and of retraction damage to the temporal lobe and brain stem were kept minimal by this approach. Total tumor resection was achieved in 7 patients, with no resultant mortality. Eight patients had a satisfactory postsurgical course, extraocular paresis being their main complaint. The extent of tumor resection depended on the degree of tumor adhesion to the carotid artery, and operative morbidity on the degree of tumor invasion of the brain stem. Of the 3 patients in whom subtotal tumor removal was achieved, only one experienced regrowth of the tumor and underwent a second operation during the follow-up period (6 months-6 years).

The TNs extending into multiple fossae can be totally removed using the following single-stage surgical techniques: Type MP by the anterior transpetrosal approach; Type ME by the zygomatic or orbitozygomatic infratemporal approach; and Type MPE by the zygomatic transpetrosal approach. In 12 of 13 cases involving multiple fossae in this series, total tumor removal was achieved using single-stage skull base surgery.

Unusually stable complexes are formed between [6]paraphenyleneacetylene ([6]CPPA, see picture) and fullerenes (either C60 or bis(ethoxycarbonyl)methanofullerene). Crystallographic analysis reveals that a major driving force for the formation of such complexes is the existence of a novel concave–convex π–π interaction (see structure).

Tumor cells arising from a particular tissue may exhibit the same gene expression patterns as their precursor cells. To test this proposition, we have analyzed the expression of a neural RNA-binding protein, Musashi1, in primary human central nervous system (CNS) tumors. In rodents, Musashi1 is expressed predominantly in proliferating multipotent neural precursor cells, but not in newly generated postmitotic neurons. The expression of Musashi1 is downregulated with the successive progression of neurogenesis. In normal adult human tissues, we detected low levels of Musashi1 expression in brain and testis by RT-PCR analysis. In an RNA panel of 32 cancer tissues and cell lines, elevated expression of Musashi1 was seen in all five malignant gliomas studied, in contrast to the slight expression seen in other tumor cells, including those in several melanomas and a prostate cancer. Western blot analysis showed strong Musashi1 expression in malignant gliomas compared with nonneoplastic brain tissue. Glioblastomas, the most malignant form of glioma, showed higher Musashi1 expression than less malignant gliomas by immunohistochemical analysis. Tumors with strong Musashi1 expression tended to have high proliferative activity. Thus, the expression of Musashi1 correlated with the grade of the malignancy and proliferative activity in gliomas. These results suggest that primary CNS tumors may share gene expression patterns with primitive, undifferentiated CNS cells and that Musashi1 may be a useful marker for the diagnosis of CNS tumors.