Fine-needle aspiration diagnosis of medulloblastoma metastatic to the pelvis.

A 25-yr-old male presented with a cerebellar mass, underwent a suboccipital craniotomy, and was diagnosed with medulloblastoma. Six months later he developed a large mass in the right iliac crest. Fine-needle aspiration biopsy (FNAB) confirmed the diagnosis of metastatic medulloblastoma. The diagnosis of metastatic medulloblastoma is usually suspected clinically or radiographically, and is uncommonly confirmed by cytologic evaluation. Here we report on a rare case of FNAB used to diagnose metastatic medulloblastoma.

GABA synthesis in astrocytes after infection with defective herpes simplex virus vectors expressing glutamic acid decarboxylase 65 or 67.

Defective herpes simplex virus (HSV) vectors containing glutamic acid decarboxylase (GAD) cDNAs, either GAD65 or GAD67, were used to examine GAD function and GABA synthesis in rat cortical astrocytes, CNS cells that do not endogenously synthesize GABA. GAD vector infection resulted in isoform-specific expression of GAD as determined by western blotting and immunohistochemistry. Astrocytes infected with a beta-galactosidase vector or uninfected expressed no GAD and contained no detectable GABA. GABA was detected in glial fibrillary acid protein-expressing cells after GAD65 vector infection. Significant amounts of GABA, as determined by HPLC, were synthesized in cultures infected with either GAD vector. The levels of GABA in GAD67 vector-infected cells were almost twofold higher than in GAD65 vector-infected cells. Vector infection did not alter levels of other intracellular amino acids. GABA was tonically released from astrocytes infected with the GAD67 vector, but no increase in release could be detected after treatment of the cells with K+, veratridine, glutamate, or bradykinin. The ability to transduce astrocytes so that they express GAD and thereby increase GABA levels provides a potential strategy for the treatment of neurologic disorders associated with hyperexcitable or diminished inhibitory activity.

Novel synthesis and release of GABA in cerebellar granule cell cultures after infection with defective herpes simplex virus vectors expressing glutamic acid decarboxylase.

The inhibitory amino acid neurotransmitter gamma-aminobutyric acid (GABA) is synthesized from glutamate in a single step by the enzyme glutamatic acid decarboxylase (GAD). We sought to determine whether viral vectors containing GAD cDNA could be used to enhance synthesis and stimulation-evoked release of GABA in cultures of CNS neurons. For this purpose, we generated double-cassette defective herpes simplex virus (HSV) vectors that expressed one of the two GAD isoforms (GAD65 or GAD67), and Escherichia coli LacZ. Infection of cerebellar granule cell (CGC) cultures with vectors containing GAD cDNA resulted in a significant increase in isoform-specific expression of GAD, synthesis of GABA, and stimulation-evoked GABA release. GAD65 and GAD67 vector-infected neurons exhibited a comparable profile of GABA levels, synthesis and release, as well as GAD protein distribution. In CGCs cultured for 6 days in vitro (DIV), GABA synthesized after vector-derived GAD expression was released by treatment with glutamate or veratridine, but only in a Ca2+-independent fashion. In more mature (10 DIV) cultures, both Ca2+-dependent, K+ depolarization-induced, as well as Ca2+-independent, veratridine-induced, GABA release was significantly enhanced by GAD vector infection. Treatment of CGCs with kainic acid, which destroys most of the GABAergic neurons (<1% remaining), did not prevent vector-derived expression of GAD nor synthesis of GABA. This suggests that defective HSV vector-derived GAD expression can be used to increase GABA synthesis and release in CNS tissue, even in the relative absence of GABAergic neurons. The use of such GAD vectors in the CNS has potential therapeutic value in neurologic disorders such as epilepsy, chronic pain, Parkinson's and Huntington's disease.

Co-expression of two gene products in the CNS using double-cassette defective herpes simplex virus vectors.

Defective herpes simplex virus (HSV) vectors are an efficient means to deliver genes to cells of the central nervous system (CNS). Such vectors containing two independent transcription units would be extremely valuable for many studies, including the comparative analysis of promoter function and expression of multiple gene products in the CNS. We have constructed a 'double-cassette' vector expressing two easily detectable marker enzymes, beta-galactosidase (beta-gal) and human placental alkaline phosphatase (AP). Cells infected in vitro, including neurons and glia, and in vivo expressed both gene products.