Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Some neurodegenerative disorders of adults involving mental retardation are associated with reduction of dendritic spines and number of synapses. A study was performed to prove the changes in the density of dendritic spines and synaptophysin-immunoreactive granules in the frontal cortex of cases with infantile brain damage and a possible correlation between them. Specimen from cortex of children and adolescents with severe mental retardation, aged 3 to 24 years and a group of non-psychiatric age-matched controls were processed according to the Golgi-Kopsch method. Density of dendritic spines on the apical dendrites of layer V pyramidal neurons (Brodman area 10) was analysed in correlation to the density of synaptophysin-reactive granules (counts/microns 2) in the same region. Both density of spines and number of immunoreactive granules were reduced in brains with infantile damages, but there was no correlation between spine density and the number of immunoreactive granules against synaptophysin.
 ...
PMID:Dendritic spines and immunoreactivity of synaptophysin in the frontal cortex of humans with infantile brain damage. A correlative study. 808 32

Three cases of subependymal giant cell astrocytoma (SEGA) in the women aged 23, 26, and 36 years were reported. Two of them had no clinical evidence of tuberous sclerosis complex (TSC) and the one woman presented apparent mental retardation. All patients manifested sudden clinical onset with symptoms of elevated intracranial pressure due to tumor of lateral ventricles and obstructive hydrocephalus. At surgery, the neoplasm was removed totally in one case and resected partially in 2 cases. Histologically, the tumors were composed of large polygonal cells with vesicular nuclei, prominent nucleoli and glassy eosinophilic cytoplasm, intermingled with spindle and small cells. In addition, multinucleated and bizarre giant cells were present, but they were very numerous in one case only. The tumor cells revealed in all cases variegated immunoreactivity for glial fibrillary acidic protein (GFAP), S-100 protein, vimentin (VIM) and neuron-specific enolase (NSE), with stronger expression of VIM than GFAP in 2 cases. Immunostaining of neurofilament proteins and synaptophysin was negative. The results suggest rather astroglial incomplete or aberrant differentiation and maturation than neuronal differentiation of tumor cells. The immunohistochemical variations of SEGA in asymptomatic TSC cases and those associated with tuberous sclerosis are discussed.
 ...
PMID:Subependymal giant cell astrocytoma: clinical, histologic and immunohistochemical characteristic of 3 cases. 959 53

1. Fragile X syndrome, the most common form of inherited mental retardation, is caused by the lack or dysfunction of fragile X mental retardation protein (FMRP). The 1304N mutation in the RNA-binding domain of FMRP results in an exceptionally severe form of mental retardation. 2. We have investigated the subcellular localization of FMRP and its 1304N-mutated form in cultured hippocampal neurons and PC12 cells, using immunofluorescence microscopy. In PC12 cells, FMRP was predominantly localized to the cytoplasm and also to the processes after differentiation by NGF. 3. In cultured hippocampal neurons, granular labeling was detected along the neuronal processes. 4. Double-labeling with synaptophysin antibody revealed FMRP at synaptic sites in neurons. 5. The 1304N mutation did not appear to affect the transport of FMRP to dendrites or its localization at synaptic sites. Thus, FMRP is a synaptic protein and the severe phenotype observed in the patient with the 1304N mutation is not produced by alterations in dendritic transport.
 ...
PMID:Subcellular localization of fragile X mental retardation protein with the I304N mutation in the RNA-binding domain in cultured hippocampal neurons. 1144 Jan 96

In recent years, improvement in diagnostic techniques has led to better recognition of "disorders of cortical development". These disorders constitute a significant cause of epilepsy, mental retardation, developmental delay and neurological deficits in childhood, and may also contribute to the pathogenesis of psychological and neurodegenerative diseases in adults. Hitherto, however, few systematic studies of the human fetal cortex have been performed, and little is known about the ontogenetic processes of the neocortex in man. The aim of the study is to establish an understanding of the developmental events that occur in the second and third trimesters of gestation, by investigating the biochemical patterns of development of the human neocortex during this period. The temporal and spatial patterns of expression of the neuronal markers gamma-aminobutyric acid (GABA), choline acetyltransferase (ChAT), dopamine beta hydroxylase (DBH), dopamine receptor DR1 and synaptophysin, as well as the glial cell markers glial fibrillary acidic protein (GFAP), S100B and excitatory amino acid transporter protein GLT-1 are delineated in the fetal cortex using immunohistochemistry. Results of this study showed that different neuronal and glial cell proteins follow different developmental patterns and many show inter- or intra-regional variations in expression. Details of these patterns are described and discussed. The early expression of these proteins suggests that they play important roles in the developmental processes of cell proliferation, migration and differentiation. Both neurotransmitters and glial cell proteins probably function outside the confines of synapses in the fetal brain, as paracrine/autocrine factors. Early developmental events seem to be dictated by an innate programme, whereas late events may be more susceptible to extrinsic influences. It is hoped that knowledge of the normal developmental process can lead to better understanding of the causes and mechanisms of "disorders of cortical development", and to better treatments.
 ...
PMID:Development of the human cerebral cortex: a histochemical study. 1259 27

Dendritic morphology of 2-week-old cultured neurons, taken from postnatal day 1 fragile X mental retardation gene1 knock out (FMR1-/-) mice hippocampus, were compared with cells taken from wild type mice. Under control conditions the FMR1-/- neurons displayed significantly lower spine densities compared to wild type neurons. Pharmacological stimulation of electrical activity, induced by bicuculline, caused a reduction in dendritic spine density in both the FMR1-/- and the wild type cells. In both groups, bicuculline induced a significant shrinkage of spines that were occupied by one or more synaptophysin-immunoreactive presynaptic terminals. The concentration of FMR1 in the wild type cultures was not affected by bicuculline treatment. These experiments indicate that FMR1 is not likely to be an essential factor in activity-modulated morphological plasticity of dendritic spines in cultured hippocampal neurons.
 ...
PMID:Is fragile X mental retardation protein involved in activity-induced plasticity of dendritic spines? 1271 Oct 73

Investigation of MR patients with 3p aberrations led to the identification of the translocation breakpoint in intron five of the neural Cell Adhesion L1-Like (CALL or CHL1) gene in a man with non-specific mental retardation and 46,Y, t(X;3)(p22.1;p26.3). The Xp breakpoint does not seem to affect a known or predicted gene. Moreover, a fusion transcript with the CALL gene could not be detected and no mutations were identified on the second allele. CALL is highly expressed in the central and peripheral nervous system, like the mouse ortholog 'close homolog to L1' (Chl1). Chl1 expression levels in the hippocampus of Chl1(+/-) mice were half of those obtained in wild-type littermates, reflecting a gene dosage effect. Timm staining and synaptophysin immunohistochemistry of the hippocampus showed focal groups of ectopic mossy fiber synapses in the lateral CA3 region, outside the trajectory of the infra-pyramidal mossy fiber bundle in Chl1(-/-) and Chl1(+/-) mice. Behavioral assessment demonstrated mild alterations in the Chl1(-/-) animals. In the probe trial of the Morris Water Maze test, Chl1(-/-) mice displayed an altered exploratory pattern. In addition, these mice were significantly more sociable and less aggressive as demonstrated in social exploration tests. The Chl1(+/-) mice showed a phenotypic spectrum ranging from wild-type to knockout behavior. We hypothesize that a 50% reduction of CALL expression in the developing brain results in cognitive deficits. This suggests that the CALL gene at 3p26.3 is a prime candidate for an autosomal form of mental retardation. So far, mutation analysis of the CALL gene in patients with non-specific MR did not reveal any disease-associated mutations.
 ...
PMID:CALL interrupted in a patient with non-specific mental retardation: gene dosage-dependent alteration of murine brain development and behavior. 1281 75

Down's syndrome (DS), with an incidence of one in 800 live births, is the most common genetic disorder associated with mental retardation. This trisomy on chromosome 21 induces a variable phenotype in which the only common feature is the presence of mental retardation. The neural mechanisms underlying mental retardation might include defects in the formation of neuronal networks and neural plasticity. DS patients have alterations in the morphology, the density and the distribution of dendritic spines in the pyramidal neurons of the cortex. Our hypothesis is that the deficits in dendritic arborization observed in the principal neurons of DS patients and Ts65Dn mice (a model for DS that mimics most of the structural alterations observed in humans) may be mediated to some extent by changes in their inhibitory inputs. Different types of interneurons control different types of inhibition. Therefore, to understand well the changes in inhibition in DS, it is necessary to study the different types of interneurons separately. We have studied the expression of synaptophysin, Glutamic acid decarboxylase-67 (GAD-67) and calcium-binding protein-expressing cells in the primary somatosensory cortex of 4-5 month old Ts65Dn mice. We have observed an increment of GAD67 immunoreactivity that is related mainly to an increment of calretinin-immunoreactive cells and among them the ones with bipolar morphology. Since there is a propensity for epilepsy in DS patients, this increase in interneurons might reflect an attempt by the system to block overexcitation rather than an increment in total inhibition and could explain the deficit in interneurons and principal cells observed in elderly DS patients.
 ...
PMID:Alteration of inhibitory circuits in the somatosensory cortex of Ts65Dn mice, a model for Down's syndrome. 2015 42

In order to understand the alcohol's toxicity to the quantitative alternations of synapses in mouse visual cortex, the expression of synaptophysin after prenatal alcohol exposure was investigated. In present study, the experimental mice at P0, P7, P14 and P30 were grouped, as control, 2 g x kg(-1) alcohol treatment and 4 g x kg(-1) alcohol treatment. The pre-synaptic elements which were used to represent synapses were marked with synaptophysin (a synaptic vesicle associated protein) by immunocytochemistry technique. The synaptophysin positive boutons in layer VI of visual cortex were imaged under laser confocal microscope. With stereological methods, the number cal density of synapse in visual cortex was calculated in different groups at various ages. Moreover, Western blotting was carried out to detect the expression of synaptophysin in visual cortex. The results showed that prenatal alcohol exposure could cause synaptic loss with long-term effect and in a dose dependent manner. For instance, there were significant difference among the different treatment groups of P0, P14 and P30 as well (P < 0.05). Western blotting supported the results of immunofluorescent labeling. In conclusion, prenatal alcohol exposure can induce the synaptic loss dose dependently and with long-term effect. Our findings implicate that the synaptic loss with long-term effect in CNS probably contributes to the lifelong mental retardation and memorial lowliness associated with childhood FAS.
 ...
PMID:[Stereological study on the synapse loss in visual cortex of mouse after prenatal alcohol exposure]. 2093 77

In humans, lack of phenylalanine hydroxylase (Pah) activity results in phenylketonuria (PKU), which is associated with the development of severe mental retardation after birth. The underlying mechanisms, however, are poorly understood. Mutations of the Pah gene in Pah(enu2)/c57bl6 mice result in elevated levels of phenylalanine in serum similar to those in humans suffering from PKU. In our study, long-term potentiation (LTP) and paired-pulse facilitation, measured at CA3-CA1 Schaffer collateral synapses, were impaired in acute hippocampal slices of Pah(enu2)/c57bl6 mice. In addition, we found reduced expression of presynaptic proteins, such as synaptophysin and the synaptosomal-associated protein 25 (SNAP-25), and enhanced expression of postsynaptic marker proteins, such as synaptopodin and spinophilin. Stereological counting of spine synapses at the ultrastructural level revealed higher synaptic density in the hippocampus, commencing at 3 weeks and persisting up to 12 weeks after birth. Consistent effects were seen in response to phenylalanine treatment in cultures of dissociated hippocampal neurones. Most importantly, in the hippocampus of Pah(enu2)/c57bl6 mice, we found a significant reduction in microglia activity. Reorganization of hippocampal circuitry after birth, namely synaptic pruning, relies on elimination of weak synapses by activated microglia in response to neuronal activity. Hence, our data strongly suggest that reduced microglial activity in response to impaired synaptic transmission affects physiological postnatal remodelling of synapses in the hippocampus and may trigger the development of mental retardation in PKU patients after birth.
...
PMID:Hippocampal synaptic connectivity in phenylketonuria. 2529 15

Hemangioblastoma is a well-circumscribed, highly vascular, lipid-rich and low-grade tumor of uncertain histogenesis. Its histopathological features have been well established. Herein, we present a case of cerebellar hemangioblastoma in a 43-year-old woman. Histologically, the tumor was predominantly composed of cellular areas showing eosinophilic or vacuolated stromal cells arranged in nests and sheets. Focally, conventional reticular areas could be seen. Additionally, in some areas, the stromal cells were arranged radially around blood vessels, exhibiting perivascular pseudorosette structures, which were similar mostly to those of ependymomas. Immunohistochemically, the stromal cells markedly showed diffused staining for Vimentin, S-100, CD56, NSE, inhibin-a, podoplanin, alpha-Thalassemia/mental retardation syndrome X and carbonic anhydrase IX, and were negative for cytokeratin, epithelial membrane antigen, oligodendrocyte transcription factor 2, neuronal nuclear antigen, synaptophysin, isocitrate dehydrogenase 1 (R132H), P53 and CD34. Interestingly, the reticular and cellular areas either showed no or individual scattering of the GFAP-positive cells, respectively, while, the perivascular pseudorosette areas strongly and diffusely expressed GFAP. Nuclear mitosis and necrosis were not observed. The MIB-1 antibody labeling index was especially low (about 3%). Based on these findings, the patient was diagnosed with cerebellar hemangioblastoma. In the present case, we documented a distinctive histological appearance of perivascular pseudorosettes in hemangioblastoma and provided the evidence for stromal cells with glial differentiation.
 ...
PMID:Cerebellar hemangioblastoma with perivascular pseudorosette formation and glial differentiation: A case report. 2821 90


1 2 Next >>