Biomedical subjects

Luciano Neder

Publications and source records attributed to Luciano Neder.

3 recordsLinked to original sources

PubMed2003

Clear cell meningioma of the fourth ventricle.

Clear cell meningioma (CCM) has been identified and included in the World Health Organization classification of CNS tumors recently. CCMs are histologically characterized by sheets of polygonal cells with clear cytoplasm, which is the expression of high glycogen concentration. Compared with other variants of meningiomas, CCMs occur in younger patients and usually are located in the spinal canal and posterior fossa, the last ones mainly in the cerebellopontine angle. Some reports suggest that CCMs have high recurrence rate and potentially aggressive behavior. Poor outcome has been shown in intracranial and spinal tumor location, but indicators that predict outcome have not been established. The authors present two cases of intracranial CCMs, with excellent outcome in patients harboring tumor location (restricted to the fourth ventricle) and some clinical particular features (young age, gender, obesity, and moderate impairment of intellectual capacity). To the best of our knowledge, these are the two first reported cases of clear cell meningioma located primarily in the fourth ventricle.

Adult↗

PubMed2002

Glutamate NMDA receptor subunit R1 and GAD mRNA expression in human temporal lobe epilepsy.

1. Molecular mechanisms underlying increased hippocampal excitability in human temporal lobe epilepsy (TLE) are largely unknown. A disturbance of the imbalance between excitatory and inhibitory neurotransmission pathways in the epileptic hippocampus may contribute substantially to a decreased seizure threshold. 2. We have extended the investigation whether TLE is associated with changes in the expression of GAD67 and NMDAR1 by assessing the relative amounts of the mRNAs in human hippocampal samples by means of semiquantitative RT-PCR. The samples included 16 hippocampal slices obtained at surgery from intractable TLE (HS, n = 14; non-HS, n = 2) and 3 postmortem control hippocampi. 3. The ratio for the GAD/NMDAR1 transcripts was significantly higher in TLE cases when compared to the nonepileptic samples. Such findings are mainly a consequence of the increased amounts of GAD mRNA detected in the epileptic hippocampus. Compared with nonepileptic samples, and without correction for neuron losses, the amounts of NMDAR1 mRNA in HS are slightly reduced, and in the non-HS samples they are significantly increased, which is consistent with an increase of NMDAR1 in the hippocampal remaining neurons, as previously reported. 4. Our results also contribute to the indication of GAD67 mRNA upregulation in human TLE. A possible functional implication for the increased GAD mRNA levels could be a mechanism to reduce neuronal hyperexcitability, synchronization, and/or the spread of seizure.

Adult↗

PubMed2002

Seizures decrease postnatal neurogenesis and granule cell development in the human fascia dentata.

PURPOSE: There is considerable controversy whether childhood seizures damage existing neurons and/or adversely affect neurogenesis and synaptogenesis. This study addressed this question by examining fascia dentata neurogenesis, cell death, and aberrant axon connections in hippocampi from children with extratemporal seizure foci. METHODS: Surgically resected (n = 53) and age-comparable autopsy (n = 22) hippocampi were studied for neuronal densities, polysialic acid (PSA) neural cell adhesion molecule (NCAM) immunoreactivity (IR), TUNEL, and neo-Timm's histochemistry. RESULTS: Compared with autopsy cases, hippocampi from children with frequent seizures showed (a) decreased fascia dentata granule cell densities; (b) decreased PSA NCAM IR cell densities in the stratum granulosum, infragranular, and hilar regions; (c) no positive TUNEL-stained cells; and (d) aberrant supragranular mossy fiber axon connections. CONCLUSIONS: These results indicate that severe seizures during early childhood are associated with anatomic signs of decreased postnatal granule cell neurogenesis (PSA NCAM IR) and aberrant mossy fiber axon connections (neo-Timm's) without evidence of seizure-induced cell death (TUNEL). In humans, these results support the concept that seizures do not damage existing neurons, but adversely affect processes involved with normal postnatal neuronal development such as neurogenesis and axon formation. Such alterations probably negatively affect normal brain development, and/or promote epileptogenesis.

Cellular Senescence↗