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B Ghetti

Publications and source records attributed to B Ghetti.

At least 127 records · Page 7Linked to original sources
PubMed1993

Dopamine-depleting effects of MPTP and reserpine in weaver mutant mice.

The number of nigral dopamine neurons and striatal dopamine levels are reduced by 70% in the adult weaver mutant mouse (wv/wv), whereas these parameters are essentially unchanged in the heterozygote (wv/+). We hypothesized that the remaining nigral dopamine neurons and/or striatal dopamine levels in the weaver would be less sensitive to neurotoxic or dopamine-depleting agents and that nigral neurons in the heterozygote would be more vulnerable. Mice were treated with the dopaminergic neurotoxin MPTP using different injection schedules and also with reserpine. There was a similar percent decrease in striatal DA in weavers and heterozygotes compared to normal mice after these treatments. We did observe a gene-dose-related lethality to the highest dose treatment with MPTP. These results suggest that the remaining dopaminergic neurons in the weaver are not different from those in normal mice in their capacity to respond to MPTP and reserpine.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1993

Regional distribution of the alternatively spliced isoforms of beta APP RNA transcript in the brain of normal, heterozygous and homozygous weaver mutant mice as revealed by in situ hybridization histochemistry.

The cellular localization of amyloid beta-protein precursor (beta APP) RNA transcripts was studied by in situ hybridization histochemistry in normal, heterozygous and homozygous weaver (wv) mutant mice, which lose midbrain dopamine (DA) neurons, cerebellar granule cells, and Purkinje cells. The beta APP gene is located at the distal end of mouse chromosome (MMU) 16, on which the wv locus has been assigned as well. Transcripts encoding isoforms beta APP695, beta APP714 and beta APP751 were present in several different brain areas of normal (+/+) mice, including hippocampus, substantia nigra (SN) pars compacta and cerebellum. The same transcripts were progressively reduced in homozygous weaver (wv/wv) SN, in correlation with DA neuron loss. The beta APP770 species--normally seen in striatum and not SN--was present in the mutant striatum. There were not any obvious changes in beta APP expression in the nigrostriatal system of weaver heterozygotes (wv/+). In normal cerebellum, Purkinje cells showed very high levels of hybridization signal for beta APP695, beta APP714 and beta APP751 RNA transcripts, and a moderate signal for the beta APP770 species. In weaver heterozygotes and homozygotes, Purkinje cells, which are typically not arranged in a monolayer, showed strong hybridization signal. No changes in beta APP mRNAs were observed in brain areas other than the cerebellum and ventral midbrain of weaver mutants. These findings suggest that the decreased beta APP gene expression seen in the cerebellum and SN of weaver mutants most likely represents an epiphenomenon of the regional nerve cell loss and, therefore, the wv gene defect on MMU 16 does not seem to influence the expression of the closely linked beta APP gene in brain areas outside the nigrostriatal pathway and cerebellar cortex.

Alternative Splicing↗
PubMed1993

Cellular distribution of the RNA transcripts of a newly discovered gene in the brain of normal, weaver, Purkinje cell degeneration and reeler mutant mice as evidenced by in situ hybridization histochemistry.

After we identified several novel cDNAs by screening a neonatal (P1) heterozygous weaver (wv/+) cerebellar cDNA expression library with a rabbit anti-mouse granule cell antiserum, we characterized and sequenced one cDNA, GCAP-8 (standing for granule cell antiserum positive, clone number 8). In this study we examined its expression and cellular distribution in adult cerebellar mutant mice as evidenced by in situ hybridization histochemistry. In wild-type (+/+) brain, strong hybridization signal is seen in cerebellum, hippocampus, substantia nigra (SN), and cerebral cortex; in the cerebellum, hybridization signal is seen in granule cells, Purkinje cells, and in cells of the deep cerebellar nuclei. In the granuloprival weaver (wv/wv) cerebellum, hybridization signal is seen mainly in Purkinje cells. GCAP-8 expression is reduced in wv/wv SN pars compacta, which is known to lose dopamine (DA) neurons. In Purkinje cell degeneration (pcd/pcd) mutants, granule cells show hybridization signal, but overall expression is decreased owing to the absence of Purkinje cells. In reeler (rl/rl) cerebellum, the strongest hybridization signal is found in a thin granule cell layer without the typical foliation pattern, while grain clusters representing ectopic Purkinje cells are observed in the subcortical white matter and the area of the deep cerebellar nuclei. GCAP-8 expression in the reeler hippocampus and cerebral cortex shows a mixing of layers, which is known to be an aspect of the histological phenotype of this mutant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Is there a significant somatodendritic uptake of dopamine in the substantia nigra? Evidence from the weaver mutant mouse.

Slices of the substantia nigra from normal mice and from mice with the weaver gene were used to study somatodendritic uptake of dopamine. The substantia nigra of the homozygous weaver mouse is deficient in both cell bodies and dendrites whereas the substantia nigra of the heterozygous weaver mouse is deficient only in dendrites. Accumulation of [3H]dopamine by nigral slices obtained from each genotype was not different from that observed in slices obtained from control mice. The observed accumulation of [3H]dopamine was apparently taking place predominantly into serotonergic and noradrenergic elements since significant reductions were obtained by both fluoxetine and desipramine at concentrations that were selective for the serotonin and norepinephrine carriers, respectively. In the absence, as well as in the presence of fluoxetine and desipramine, dopamine accumulation in the substantia nigra was only slightly attenuated by the known dopamine uptake blocker GBR 12909. These data argue against a significant presence of somatodendritic uptake systems for dopamine in the substantia nigra and suggest that caution be used in the interpretation of results from studies on dopamine release from nigral slices when [3H]dopamine has been used to preload the tissue. Under such experimental conditions, it is likely that a large proportion of the released tritium might come from neurons other than those which contain endogenous neurotransmitter dopamine.

Animals↗
PubMed1993

Beta PP participates in PrP-amyloid plaques of Gerstmann-Sträussler-Scheinker disease, Indiana kindred.

Gerstmann-Sträussler-Scheinker disease in the Indiana kindred is pathologically characterized by deposits of PrP-amyloid, neurofibrillary tangles and degenerating neurites. The aim of this study was to investigate seven patients of different ages for beta PP and A beta immunoreactivities associated with PrP-amyloid deposits and degenerating neurites. In one asymptomatic individual with PrP-amyloid deposits, Alz50 and A beta immunoreactivities were absent. In six symptomatic patients, the degenerating neurites surrounding PrP-amyloid deposits were labeled by Alz50 and by antibodies to synaptophysin, ubiquitin and the N- and C-terminal domains of beta PP. In one symptomatic, senile patient, A beta immunoreactivity was present in the extracellular space, often in association with PrP-amyloid deposits. The analysis of the immunohistochemical findings suggested that in the Indiana kindred the intracellular accumulation of beta PP, synaptophysin and ubiquitinated material most probably revealed a reaction of neurites to PrP-amyloid, whereas the extracellular deposition of A beta was likely an age-related phenomenon.

Aged↗
PubMed1993

RFLP analysis for APP 717 mutations associated with Alzheimer's disease.

Familial Alzheimer's disease (FAD) has been shown to be associated with three distinct point mutations within the same codon of the amyloid precursor protein (APP) gene. The mutation identified in the Indiana kindred is a G-->T transversion at the first position of the codon for amino acid 717, resulting in a substitution of phenylalanine for valine in the APP protein. Screening of persons at risk for the APP Phe-717 mutation using a variation of the polymerase chain reaction identified nine positives among 34 tested. In addition, DNA from 145 FAD subjects were tested for the three known APP 717 mutations.

Alzheimer Disease↗
PubMed1993

Hypospermatogenesis is the cause of infertility in the male weaver mutant mouse.

The pathologic phenotype of the testis in both prepuberal and postpuberal male weaver mutant mice was studied by light microscopy. Morphometric analysis of seminiferous tubules was carried out. Epididymal fluid was examined for the presence of spermatozoa. The seminiferous tubules of 21-day-old prepuberal weaver mutant mice lacked patent lumina and had more degenerated cells than control mice. Fifty-six day-old weaver mutants had many germinal epithelial cells located within the adluminal compartment that were in advanced stages of degeneration. Round spermatids were enlarged and multinucleated. Round spermatids and spermatocytes had sloughed into the lumen. Compared to control mice, elongated spermatids were seen less frequently. In older weaver mice, the degenerative process involved germ cells in both the adluminal and basal compartments. In 143- and 226- day-old weaver mutants, the Sertoli cells were atrophic. Diameters of seminiferous tubules in weaver mice were significantly reduced when compared to control mice. Sperm were either absent or very low in number in the epididymal fluid of postpuberal weaver mice. We conclude that spermatogenesis is abnormal in male weaver mutant mice. The testicular phenotype is characterized by a degenerative process that affects both germ cells and supporting cells.

Aging↗
PubMed1993

Embryonic cerebellar graft development during acute phase of gliosis in the cerebellum of pcd mutant mice.

Anatomical and biochemical changes in cerebellum after the onset of pcd gene defects have revealed in addition to Purkinje cell degeneration, the occurrence of secondary degenerative events in granule neurons, neurons of the inferior olivary complex and deep cerebellar nuclei. Transplantation in young mutant animals thereby presents a prospect that not only the missing Purkinje cells may be replaced but the subsequent transneuronal losses may be minimized. The present study has evaluated the outcome of implanting embryonic cerebellar cell suspensions into pcd mutants at the age of 45 day-old, a stage marked by the end of Purkinje cell degeneration. Immunocytochemistry (ICC) was used to monitor the extent of gliosis in host cerebellum and to trace the development of embryonic Purkinje cells grafted. The results suggest that the donor cells have no apparent difficulty in survival during reactive gliosis. Migration of these neuroblasts from the grafted zone into adjacent host molecular layer and significant expression of calcium binding protein (CaBP) by grafted Purkinje cells were noted within 9 days after transplantation. Dendritic patterns of grafted Purkinje cells are well-developed by day 17 post transplantation up to 3 months. In addition, synaptic contacts between host fiber endings and the CaBP-positive dendritic spines are present in the molecular layer of folia containing the graft, suggesting synaptic integration between graft and host.

Acute Disease↗
PubMed1992

Prion protein preamyloid and amyloid deposits in Gerstmann-Sträussler-Scheinker disease, Indiana kindred.

Gerstmann-Sträussler-Scheinker disease (GSS) is a familial neurological disorder pathologically characterized by amyloid deposition in the cerebrum and cerebellum. In GSS, the amyloid is immunoreactive to antisera raised against the prion protein (PrP) 27-30, a proteinase K-resistant peptide of 27-30 kDa that is derived by limited proteolysis from an abnormal isoform of a neuronal sialoglycoprotein of 33-35 kDa designated PrPSc. Polyclonal antibodies raised against synthetic peptides homologous to residues 15-40 (P2), 90-102 (P1), and 220-232 (P3) of the amino acid sequence deduced from hamster PrP cDNA were used to investigate immunohistochemically the distribution of PrP and PrP fragments in the brains of two patients from the Indiana kindred of GSS. Two types of anti-PrP-immunoreactive deposits were found: (i) amyloid deposits, which were exclusively labeled by anti-P1 antiserum to residues 90-102 of PrP, and (ii) preamyloid deposits, which were labeled by all anti-PrP antisera but did not exhibit the tinctorial and optical properties of amyloid. The latter appeared as diffuse immunostaining of the neuropil that targeted to areas in which amyloid deposits were most abundant. They were partially resistant to proteinase K digestion and consisted ultrastructurally of amorphous, flaky, electron-dense material. These findings substantiate our previous observation that the major amyloid component in the GSS Indiana kindred is an internal fragment of PrP and indicate that full-length abnormal isoforms of PrP and/or large PrP fragments accumulate in brain regions most affected by amyloid deposition. These findings support the view that in the GSS Indiana kindred a stepwise degradation of PrP occurs in situ in the process of amyloid fibril formation.

Aged↗
PubMed1992

Low cerebrospinal-fluid concentrations of soluble amyloid beta-protein precursor in hereditary Alzheimer's disease.

In Alzheimer's disease, deposits of amyloid beta-protein are apparently derived from intracellular processing of a large precursor protein. We have measured concentrations of this precursor in cerebrospinal fluid (CSF) from six members of a family affected by presenile Alzheimer's disease associated with a point mutation of the precursor gene. One gene carrier with clinical signs of the disorder had low CSF concentrations of the precursor, similar to those of three patients with sporadic Alzheimer's disease subsequently confirmed at necropsy. Two symptom-free gene carriers had CSF precursor concentrations similar to those of non-demented controls, though the value was lower in one, who had deficits revealed on neuropsychological testing, than in the other. These findings suggest that low concentrations of soluble amyloid precursor proteins in the CSF reflect the process that results in amyloid plaque formation and vascular deposition in Alzheimer's disease.

Adult↗
PubMed1992

Spectrum of amyloid beta-protein immunoreactivity in hereditary Alzheimer disease with a guanine to thymine missense change at position 1924 of the APP gene.

We studied neuropathologically 3 patients of a previously unreported kindred of presenile Alzheimer disease (AD), characterized by a G to T mutation at base pair 1924 (695 transcript) of the amyloid precursor protein gene. Classic features of presenile AD are observed. Neurofibrillary tangles with paired helical filaments as well as neuritic plaques are found in large number in neocortex and hippocampus. beta-Protein deposits in meningeal and parenchymal vessels are present, but not severe. Prominent subpial ribbon-like deposits are detected with antibodies to a 28-residue synthetic peptide; however, only occasionally can they be seen in thioflavin S treated sections. Along with a mild involvement of vessels, as demonstrated by beta-protein immunolabeling, parenchymal involvement is also seen in the cerebellar molecular layer. In the course of the study, we have not detected neuropathologic changes, which are mutation specific. Further investigations of familial Alzheimer disease with known genetic mutations will clarify whether correlations exist between specific mutations and neuropathologic phenotypes.

Adult↗
PubMed1992

Abnormal eye movements in Gerstmann-Sträussler-Scheinker disease.

Gerstmann-Sträussler-Scheinker disease is a familial disorder of progressive ataxia and dementia in adulthood with extrapyramidal signs in some families. Neuro-ophthalmic examinations and eye movement recordings were performed in members of a large Indiana kindred. Five affected members and 11 members at risk were studied. Eye movements were recorded with videotape, electro-oculography, and/or magnetic scleral search coil. All affected members had abnormal eye movements characteristic of extrapyramidal diseases and cerebellar disorders. Nine members at risk had normal eye movements, but two others had slightly abnormal eye movements. Neuro-ophthalmic examination and eye movement recordings might be helpful in detecting early signs of Gerstmann-Sträussler-Scheinker disease in persons at risk.

Adolescent↗
PubMed1992

Intraparenchymal grafting of cerebellar cell suspensions to the deep cerebellar nuclei of pcd mutant mice, with particular emphasis on re-establishment of a Purkinje cell cortico-nuclear projection.

In transplanting embryonic cerebellar grafts to the cerebellar cortex of "Purkinje cell degeneration" (pcd) mutant mice to replace missing Purkinje cells (PC), donor PC leave the graft and migrate to the molecular layer of the host. However, PC axons do not always reach the deep cerebellar nuclei of the host, which would be a key element in restoring much of the necessary inhibitory cortico-nuclear projection associated with normal cerebellar function. Rather, grafted PC axons often innervate a region containing deep cerebellar nuclei neurons inside the transplant, while the perikaryon migrates to the host molecular layer. In the present study, aimed at re-establishing a PC innervation of the deep nuclei, we implanted E12 cerebellar cell suspensions intraparenchymally to the deep cerebellar mass of the hosts. The development of grafted PC was monitored with 28-kDa calcium-binding protein (CaBP) immunocytochemistry at various times after transplantation. At short survival times (5 days after grafting), grafts were confined to the site of the original injection. At longer survival times (7-32 days after grafting), grafted PC formed a migratory stream that reached the cerebellar cortex of the host. The most robust graft development was seen 1 month after grafting, the longest survival time allowed in this series of experiments. At that time, clusters of donor PC were found both in the deep nuclei parenchyma and aligned along cortical folia. The orientation of the dendritic trees of PC that had migrated to the cortex was toward the pia. A CaBP-immunoreactive fibre plexus innervated the host deep cerebellar nuclei. The stream of grafted PC extended from the deep cerebellar nuclei to the cerebellar cortex of the host, indicating that donor PC could establish their axonal contacts in the deep nuclei and then move to their final cortical locality, thus recapitulating a migratory path normally taken during cerebellar ontogeny. It appears therefore that both from the pathophysiological and ontogenetic standpoints, the deep cerebellar nuclei represent the appropriate site for PC implantation in cerebellocortical atrophy.

Animals↗
PubMed1992

Topographic distribution of dopamine uptake, choline uptake, choline acetyltransferase, and GABA uptake in the striata of weaver mutant mice.

The topographic distribution of dopamine (DA) uptake, choline uptake, choline acetyltransferase (ChAT) activity and GABA uptake within the striata of weaver mutant mice and control mice was determined. Uptake of [3H]dopamine, [3H]choline and [14C]GABA, as well as ChAT activity were determined in samples prepared from the dorsolateral, dorsomedial, ventrolateral and ventromedial portions of the striatum. In 45-60 day old control mice, dopamine uptake was homogeneously distributed throughout the striatum. On the other hand, striata from weaver mice exhibited an uneven distribution with the ventral aspects having greater uptake activity than the dorsal regions. Thus, although the ventral portion of the striatum is less severely affected than the dorsal portion, all areas of the striatum exhibited significantly reduced uptake rates. In 9 and 12 month old mice, choline uptake was higher in lateral than medial zones of the striatum of both genotypes and no differences were observed between genotypes. GABA uptake was higher in the ventral striatum than in the dorsal striatum but again no differences were found between weaver and control mice. The results of this study indicate that the entire weaver striatum is severely deficient in its ability to recapture dopamine and thus is functionally compromised. The results also indicate that the striatal cholinergic and GABAergic interneurons are not directly or indirectly affected by the weaver gene.

Animals↗
PubMed1992

Comparison of alterations in tyrosine hydroxylase, dopamine levels, and dopamine uptake in the striatum of the weaver mutant mouse.

Previous reports have shown that among the markers for the nigro-striatal dopamine (DA) system measured in the striatum, dopamine uptake seems to be more severely affected than the others in the weaver mutant mouse. In the present study we examined DA levels, tyrosine hydroxylase (TH) activity, and high-affinity DA uptake to determine if the DA uptake is most affected when all the measurements are made in the same striatal homogenate in the same laboratory. We found that the DA uptake activity was most altered (93% lower) compared to DA levels (68% lower) and TH activity (64% lower). The DA uptake was so low in the weaver that we could not obtain reliable kinetic parameters. For TH activity we found that the Vmax was 36% lower while the Km for L-tyrosine was 92% higher in the weaver striatum. This lower affinity for substrate suggests that the TH enzyme itself may be altered in the nigro-striatal system of the weaver mutant mouse.

Animals↗
PubMed1992

Serotonin fiber innervation of cerebellar cell suspensions intraparenchymally grafted to the cerebellum of pcd mutant mice.

One aspect of integration of implanted neurons into the neuronal circuitry of a defective host brain is the re-establishment of a host-to-graft afferent innervation. We addressed this issue by using the adult cerebellum of 'Purkinje cell degeneration' (pcd) mutant mice, which lack virtually all Purkinje cells after postnatal day (P) 45. Purkinje cells constitute one of the cerebellar cell types being innervated by axons of raphé serotonin (5-HT) neurons. In normal mice, 5-HT-immunoreactive fibers are distributed to all cerebellar folia. Following Purkinje cell loss in pcd mice, cerebellar 5-HT-immunoreactive fibers persist. Cerebellar cell suspensions were prepared from embryonic day (E) 11-13 normal mouse embryos and were intraparenchymally grafted into the cerebellum of pcd mutants either directly or after pre-treatment with 5,7-dihydroxytryptamine (5,7-DHT) to selectively remove 5-HT cells of donor origin. The state of Purkinje cells and 5-HT axons was monitored in alternate sections by 28-kDa Ca(2+)-binding protein (CaBP) and 5-HT immunocytochemistry, respectively. Serotonin-immunoreactive axons were seen in the grafts from 5 to 32 days after transplantation. In some of the grafts which had not been pre-treated with 5,7-DHT, a small number of 5-HT-immunoreactive cell bodies was found, indicating that part of the 5-HT fiber innervation of the graft could actually derive from donor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

5,7-Dihydroxytryptamine↗
PubMed1992

Linkage of the Indiana kindred of Gerstmann-Sträussler-Scheinker disease to the prion protein gene.

The Indiana kindred variant of Gerstmann-Sträussler-Scheinker disease has amyloid plaques that contain prion protein (PrP), but is atypical because neurofibrillary tangles like those of Alzheimer disease are present. To map the position of the disease causing gene, we used three markers for linkage analyses. A missense mutation at codon 198 of the PrP gene (PRNP) is found in all definitely affected individuals and yields a maximum lod score of 6.37 (theta = 0). The disease also is concordant with the two other PRNP-region markers. These results demonstrate tight linkage of the disease-causing gene to PRNP and support the hypothesis that the codon 198 mutation is the cause of IK-GSS. Our studies also suggest that methionine/valine heterozygotes at PRNP codon 129 have a later age of onset of the disease than codon 129 valine/valine homozygotes.

Adult↗