PubMed Health⌕ Search

Biomedical subjects

L S Dure

Publications and source records attributed to L S Dure.

At least 37 records · Page 2Linked to original sources
PubMed1992

Preferential loss of striato-external pallidal projection neurons in presymptomatic Huntington's disease.

We have reported previously that striatal projection neurons are differentially affected in the course of Huntington's disease, and in a prior patient report we noted that differential loss of striatal projection neurons occurs also in patients with presymptomatic Huntington's disease. Striatal neurons projecting to the external segment of the globus pallidus or the substantia nigra show evident loss, whereas those projecting to the internal segment of the globus pallidus appear relatively spared at presymptomatic and early stages of symptomatic Huntington's disease. We now report similar findings in a second apparently presymptomatic Huntington's disease allele carrier.

Adult↗
PubMed1992

Excitatory amino acid binding sites in the basal ganglia of the rat: a quantitative autoradiographic study.

Quantitative receptor autoradiography was used to determine the distribution of excitatory amino acid binding sites in the basal ganglia of rat brain. alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid, N-methyl-D-aspartate, kainate, quisqualate-sensitive metabotropic and non-N-methyl-D-aspartate, non-kainate, non-quisqualate glutamate binding sites had their highest density in striatum, nucleus accumbens, and olfactory tubercle. Kainate binding was higher in the lateral striatum but there was no medial-lateral striatal gradient for other binding sites. N-Methyl-D-aspartate and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid binding sites were most dense in the nucleus accumbens and olfactory tubercle. There was no dorsal-ventral gradient within the striatal complex for the other binding sites. Other regions of the basal ganglia had lower densities of ligand binding. To compare binding site density within non-striatal regions, binding for each ligand was normalized to the striatal binding density. When compared to the striatal complex, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and metabotropic binding sites had higher relative density in the globus pallidus, ventral pallidum, and subthalamic nucleus than other binding sites. Metabotropic binding also had a high relative density in the substantia nigra. Non-N-methyl-D-aspartate, non-kainate, non-quisqualate glutamate binding sites had a high relative density in globus pallidus, ventral pallidum, and substantia nigra. N-Methyl-D-aspartate binding sites had a low relative density in pallidum, subthalamic nucleus, substantia nigra and ventral tegmental area. Our data indicate heterogeneous distribution of excitatory amino acid binding sites within rat basal ganglia and suggest that the character of excitatory amino acid-mediated neurotransmission within the basal ganglia is also heterogeneous.

Animals↗
PubMed1991

Excitatory amino acid binding sites in the caudate nucleus and frontal cortex of Huntington's disease.

Huntington's disease is a dominantly inherited, progressive neurodegenerative disorder causing marked pathology in the basal ganglia. The pathophysiology of the selective neuronal death is as yet unknown, but evidence suggests that the neurotoxicity may result from endogenous substances acting at excitatory amino acid receptors. Previous data have shown a selective decrease in binding to one class of glutamate receptors, the N-methyl-D-aspartate (NMDA) receptor in the putamen of Huntington's disease. The present study was undertaken to determine the relative density of binding to all of the currently defined subpopulations of excitatory amino acid receptors in the caudate nuclei and frontal cortex of patients with Huntington's disease and of control subjects, using quantitative in vitro autoradiography. NMDA, MK-801, glycine, kainate, and alpha-amino-3-hydroxy-5-methylisoxazole propionic acid (AMPA) receptor binding were all decreased to a similar extent (50-60%). Binding to the metabotropic quisqualate receptor and to the non-NMDA, nonkainate, nonquisqualate (NNKQ) site was decreased nonsignificantly by 31% and 26%, respectively. Autoradiograms of NMDA, MK-801, AMPA, kainate, metabotropic, and NNKQ receptors in caudates revealed an inhomogeneous pattern of binding that is different from the binding pattern seen in control caudates. Binding to all receptor subtypes was the same in the frontal cortex from Huntington's disease patients and control subjects. The data suggest that no single excitatory amino acid receptor is selectively decreased in the caudate of Huntington's disease.

Adolescent↗
PubMed1990

Excitatory amino acid binding sites in the periaqueductal gray of the rat.

We used receptor autoradiography to determine the distribution of excitatory amino acid (EAA) binding site subtypes in the periaqueductal gray (PAG) of the rat. N-Methyl-D-aspartate (NMDA), kainate, quisqualate-ionotropic, and quisqualate-metabotropic binding sites were all present in the PAG. Distribution was inhomogeneous with greatest density of all binding site subtypes in the dorsolateral subdivision and lowest density in the ventrolateral subdivision. Relative to regions of brain with high densities of EAA binding site subtypes, quisqualate-metabotropic binding sites had the highest relative density and NMDA binding sites the least. The presence of all subtypes of EAA binding sites in the PAG suggests that EAA action within the PAG is likely to be complex.

Amino Acids↗
PubMed1989

Chiari type I malformation in children.

We reviewed the recent experience at Texas Children's Hospital by examining the records of 11 children who underwent suboccipital decompression for symptomatic Chiari type I malformation. Presenting complaints included neck pain (1 child), scoliosis (4 children), back pain (1 child), torticollis (1), motor dysfunction (1), and apnea (3 children). Neurologic findings were normal in 7 of the 11 children. The craniocervical junction and medulla were studied by magnetic resonance imaging, which revealed anatomy consistent with Chiari type I malformation in all cases. At surgery, all patients had tonsillar herniation to the first cervical vertebra or below. Three patients had syringomyelia. Postoperatively, either the patients were symptom free or, in the cases of scoliosis and torticollis, there was no progression. Our experience suggests that Chiari type I malformation may occur in childhood with varied and unusual clinical findings. Magnetic resonance imaging was essential to the diagnosis; the presence of tonsillar herniation was confirmed at surgery. The results of suboccipital decompression were favorable in this series.

Adolescent↗
PubMed1981

Cotton messenger RNA sequences exist in both polyadenylated and nonpolyadenylated forms.

The physical characteristics and sequence content of polyadenylated and nonpolyadenylated messenger RNAs were determined in total and polysomal RNAs isolated from cotton cotyledons after 24 h of germination. RNAs were fractionated on the basis of their poly(A) content by passage through poly(U)-agarose. The mass average size of poly(A) is 112 +/- 4 nucleotides in total RNA and 81 +/- 3 nucleotides in polysomal RNA. Less than 2% of the poly(A) tracts are between 5-15 nucleotides in length. The mass average length of recovered polyadenylated mRNAs from either RNA is 1600 nucleotides. In vitro translation of the RNAs in the wheat germ system and hybridization of the RNAs with complementary DNAs confirmed the physical estimates of their absolute amounts. About 3.3% of the high molecular weight RNA in the tissue is mRNA, of which 40% is on polysomes. Abut 45% of the polysomal mRNA and 75% of the nonpolysomal mRNA is polyadenylated. These mRNAs are transcribed from nonrepetitive DNA. Both techniques unambiguously demonstrate that all mRNA populations contain the same sequences in about the same relative concentration. At this point of development in this tissue, differential polyadenylation or entry into polysomes cannot be specific for particular mRNA sequences.

Gossypium↗
PubMed1975

The developmental biochemistry of cotton seed embryogenesis and germination. VI. Levels of cytosol and chloroplast aminoacyl-tRNA synthetases during cotyledon development.

The separation of isotransferring aminoacyl-tRNA synthetase activities (amino acid: tRNA ligases, EC 6.1.1.x) for several amino acids extracted from tissues of embryonic and germinating cotton seeds was carried out by DEAE-cellulose column chromatography. Evidence was obrained that the separated activities represent discrete enzymes, and could be defined as cytosol or chloroplast enzymes by several criteria. The levels of the cytosol enzymes per cell were found to be constant in germinated and ungerminated cotyledons. Chloroplast enzymes were found to be present in immature embryonic cotyledons and in roots at constant levels relative to the cytosol enzymes, but found to increase markedly in germinating cotyledons. This increase takes place to the same extent in etiolated cotyledons as in greened cotyledons indicating that the chloroplast synthetase increase is analogous to the simultaneous increase in chloroplast tRNA and rRNA which also is not light dependent. The separated cytosol and chloroplast enzymes show varying degrees of specificity for isoaccepting tRNA species from homologous and heterologous sources.

Amino Acyl-tRNA Synthetases↗