6 research outputs found
Spatial and verbal working memory: A functional magnetic resonance imaging study
According to numerous studies, working memory is not a unitary system. Baddeley's model of working memory includes besides central executive also two separate systems for verbal and visuo-spatial information processing. A modality- and process-specific specialization presumably exists in working memory system of the frontal lobes. In our preliminary study, we have used functional magnetic resonance imaging to study the pattern of cortical activation during spatial and verbal n-back task in six healthy subjects. A bilateral fronto-parietal cortical network was activated in both tasks. There was larger activation of right parietal and bilateral occipital areas in spatial than in vebal task. Activation of left sensorimotor area was larger in verbal compared to spatial task. No task-specific differences were found in the prefrontal cortex. Our results support the assumption that modality-specific processes exist within the working-memory system
Loss of H3K27me3 expression in canine nerve sheath tumors
Nerve sheath tumors (NSTs) are characterized by neoplastic proliferation of
Schwann cells, perineurial cells, endoneurial and/or epineurial fibroblasts.
Diagnosis of NST is often challenging, particularly in distinguishing malignant
NST (MNST) from other soft tissue sarcomas, or sometimes between low-
grade MNST and benign NST. Recent studies in human pathology have
demonstrated loss of trimethylation at lysine 27 of histone 3 (H3K27me3) in a
subset of MNSTs using immunohistochemistry. Loss of H3K27me3 expression
is rare in other high-grade sarcomas and also appears to be useful in
distinguishing benign and low-grade MNSTs from high-grade subsets. In our
retrospective study, we performed H3K27me3 immunohistochemistry in 68
canine tumors previously diagnosed as NST. We detected loss of H3K27me3
expression in 25% (n = 17) of all canine NST, including one neurofibroma,
whereas 49% (n = 33) of tumors had mosaic loss of expression and 26%
(n = 18) retained expression. No statistically significant differences were found
between H3K27me3 expression, histopathological features of tumors, and
their immunoreactivity for Sox10, claudin-1, GFAP, and Ki67. Because the
classification of canine NST is not yet fully established and its correlation with
the prognosis and clinical course of the disease is lacking, prospective studies
with possible genetic analyses are needed to assess the true diagnostic value
of H3K27me3 loss in canine NST