Search PubMed⌕ Search

Biomedical subjects

S Minoshima

Publications and source records attributed to S Minoshima.

At least 37 records · Page 2Linked to original sources
PubMed2001

Parkin is associated with cellular vesicles.

We recently identified a novel gene, parkin, as a pathogenic gene for autosomal recessive juvenile parkinsonism. Parkin encodes a 52-kDa protein with a ubiquitin-like domain and two RING-finger motifs. To provide a insight into the function of parkin, we have examined its intracellular distribution in cultured cells. We found that parkin was localized in the trans-Golgi network and the secretory vesicles in U-373MG or SH-SY5Y cells by immunocytochemical analyses. In the subsequent subcellular fractionation studies of rat brain, we showed that parkin was copurified with the synaptic vesicles (SVs) when we used low ionic conditions throughout the procedure. An immunoelectromicroscopic analysis indicated that parkin was present on the SV membrane. Parkin was readily released from SVs into the soluble phase by increasing ionic strength at neutral pH, but not by a non-ionic detergent. To elucidate its responsible region for membrane association, we transfected with green fluorescent protein-tagged deletion mutants of parkin into COS-1 cells followed by subcellular fractionation. We demonstrated the ability of parkin to bind to the membranes through a broad region except for the ubiquitin-like domain. The significance of SV localization of parkin is discussed.

Animals↗
PubMed2001

Developmental changes in the expression of parkin and UbcR7, a parkin-interacting and ubiquitin-conjugating enzyme, in rat brain.

Parkin is a product of the Park2 gene the mutation of which causes autosomal recessive juvenile parkinsonism (AR-JP) characterized by selective dopaminergic neuronal death and absence of Lewy bodies. Recently we found that parkin is directly linked to the ubiquitin (Ub)-proteasome pathway as a Ub-protein ligase (E3) collaborating with a Ub-conjugating enzyme (E2) UbcH7. Here we analysed by in situ hybridization the expression of mRNAs for parkin and UbcR7 (rat orthologue of human UbcH7) in the developing rat brain. Parkin mRNA increased in parallel with neuronal maturation, but was unevenly distributed in various brain regions after four postnatal days. The expression pattern of the UbcR7 mRNA was almost identical to that of the parkin mRNA in all cases examined. Both parkin and UbcR7 mRNAs were distributed in neurones but not glial cells. Our findings indicate that parkin is expressed not only in the substantia nigra, but also uniformly in various brain regions in a development-dependent manner. Co-expression of UbcR7 with parkin suggests that UbcR7 may interact with parkin in vivo for ubiquitination of yet unidentified target protein(s).

Animals↗
PubMed2001

Gastric distention correlates with activation of multiple cortical and subcortical regions.

BACKGROUND & AIMS: The pathophysiology of functional dyspepsia may involve abnormal processing of visceral stimuli at the level of the central nervous system. There is accumulating evidence that visceral and somatic pain processing in the brain share common neuronal substrates. However, the cerebral loci that process sensory information from the stomach are unknown. The aim of this study was to localize the human brain regions that are activated by gastric distention. METHODS: Brain (15)O-water positron emission tomography was performed in 15 right-handed healthy volunteers during baseline and distal gastric distentions to 10 mm Hg, 20 mm Hg, threshold pain, and moderate pain. Pain, nausea, and bloating were rated during baseline and distentions (0-5 scale). Statistical subtraction analysis of brain images was performed between distentions and baseline. RESULTS: Symptoms increased with distending stimulus intensity (maximum pain, 2.1 +/- 0.4; nausea, 2.2 +/- 0.4; bloating, 3.7 +/- 0.2). Paralleling increases in distention stimulus and symptoms, progressive increases in activation (P < or = 0.05), were observed in the thalami, insula bilaterally, anterior cingulate cortex, caudate nuclei, brain stem periaqueductal gray matter, cerebellum, and occipital cortex. CONCLUSIONS: Symptomatic gastric distention activates structures implicated in somatic pain processing, supporting the notion of a common cerebral pain network.

Adult↗
PubMed2001

Analysis of the cat eye syndrome critical region in humans and the region of conserved synteny in mice: a search for candidate genes at or near the human chromosome 22 pericentromere.

We have sequenced a 1.1-Mb region of human chromosome 22q containing the dosage-sensitive gene(s) responsible for cat eye syndrome (CES) as well as the 450-kb homologous region on mouse chromosome 6. Fourteen putative genes were identified within or adjacent to the human CES critical region (CESCR), including three known genes (IL-17R, ATP6E, and BID) and nine novel genes, based on EST identity. Two putative genes (CECR3 and CECR9) were identified, in the absence of EST hits, by comparing segments of human and mouse genomic sequence around two solitary amplified exons, thus showing the utility of comparative genomic sequence analysis in identifying transcripts. Of the 14 genes, 10 were confirmed to be present in the mouse genomic sequence in the same order and orientation as in human. Absent from the mouse region of conserved synteny are CECR1, a promising CES candidate gene from the center of the contig, neighboring CECR4, and CECR7 and CECR8, which are located in the gene-poor proximal 400 kb of the contig. This latter proximal region, located approximately 1 Mb from the centromere, shows abundant duplicated gene fragments typical of pericentromeric DNA. The margin of this region also delineates the boundary of conserved synteny between the CESCR and mouse chromosome 6. Because the proximal CESCR appears abundant in duplicated segments and, therefore, is likely to be gene poor, we consider the putative genes identified in the distal CESCR to represent the majority of candidate genes for involvement in CES.

Abnormalities, Multiple↗
PubMed2001

A SNP resource for human chromosome 22: extracting dense clusters of SNPs from the genomic sequence.

The recent publication of the complete sequence of human chromosome 22 provides a platform from which to investigate genomic sequence variation. We report the identification and characterization of 12,267 potential variants (SNPs and other small insertions/deletions) of human chromosome 22, discovered in the overlaps of 460 clones used for the chromosome sequencing. We found, on average, 1 potential variant every 1.07 kb and approximately 18% of the potential variants involve insertions/deletions. The SNPs have been positioned both relative to each other, and to genes, predicted genes, repeat sequences, other genetic markers, and the 2730 SNPs previously identified on the chromosome. A subset of the SNPs were verified experimentally using either PCR-RFLP or genomic Invader assays. These experiments confirmed 92% of the potential variants in a panel of 92 individuals. [Details of the SNPs and RFLP assays can be found at http://www.sanger.ac.uk and in dbSNP.]

Base Composition↗
PubMed2001

Temporal and spatial dynamics of human forebrain activity during heat pain: analysis by positron emission tomography.

To learn about the sequence of brain activation patterns during heat pain, we acquired positron emission tomographic (PET) brain scans at different times during repetitive heat stimulation (40 or 50 degrees C; 5-s contact) of each subject's left forearm. Early scans began at the onset of 60 s of stimulation; late scans began after 40 s of stimulation, which continued throughout the 60-s scan period (total stimulus duration 100 s). Each subject (14 normal, right-handed subjects; 10 male, 4 female; ages 18-42) used a visual analog scale to rate the perceived stimulus intensity (0 = no heat, 7 = pain threshold, 10 = barely tolerable pain) after each scan. The 40 degrees C stimulation received an average intensity rating of 2.19 +/- 1.22 (mean +/- SD) and the 50 degrees C an average rating of 8.93 +/- 1.33. During the scan sessions, subjects did not report a difference between early and late scans. To examine the effect of the duration of stimulation specifically, 8 of these subjects rated the perceived intensity of each of 20 sequential 5-s duration contact heat stimuli (40 or 50 degrees C; 100 s of stimulation). We used a graphical method to detect changes in perceived unpleasantness. There was no difference in perceived intensity or unpleasantness during the 40 degrees C stimulation. However, during 50 degrees C stimulation, perceived unpleasantness increased and subjects perceived the last five, but not the second five, stimuli as more intense than the first five stimuli. These psychophysical changes could be mediated by brain structures with increasing activity from early to late PET scans or that are active only during late scans. These structures include the contralateral M1/S1 cortex, bilateral S2 and mid-insular cortex, contralateral VP thalamus, medial ipsilateral thalamus, and the vermis and paravermis of the cerebellum. Structures that are equally active throughout stimulation (contralateral mid-anterior cingulate and premotor cortex) are less likely to mediate these psychophysical changes. Some cortical, but not subcortical, structures showed significant or borderline activation only during the early scans (ipsilateral premotor cortex, contralateral perigenual anterior cingulate, lateral prefrontal, and anterior insular cortex); they may mediate pain-related attentive or anticipatory functions. Overall, the results reveal that 1) the pattern of brain activation and the perception of heat pain both change during repetitive noxious heat stimulation, 2) cortical activity can be detected before subcortical responses appear, and 3) timing the stimulation with respect to the scan period can, together with psychophysical measurements, identify brain structures that are likely to participate in the perception of pain.

Adult↗
PubMed2001

Effects of long-term hormone therapy on cholinergic synaptic concentrations in healthy postmenopausal women.

Experimental evidence suggests that gonadal steroids regulate brain neurochemical systems associated with cognitive function, such as the cholinergic system. This study examines the effect of long-term postmenopausal hormone therapy on the brain concentrations of cholinergic synaptic terminals in women using single photon emission computed tomography and the radiotracer [(123)I]iodobenzovesamicol ([(123)I]IBVM). [(123)I]IBVM labels the vesicular acetylcholine transporter (VAChT) located in the presynaptic terminals of these neurons. Sixteen healthy women treated with hormone therapy since the menopause and 12 women not treated with hormones were studied. There were no significant differences in regional IBVM binding indexes between the 2 groups. The length of hormone replacement therapy correlated positively with VAChT binding indexes in multiple cortical areas (P < 0.05): frontal cortex (Spearman rank correlation: rho = 0.79), parietal cortex (rho = 0.62), temporal cortex (rho = 0.80), anterior cingulate (rho = 0.71), and posterior cingulate (rho = 0.63), but not in the basal ganglia (rho = 0.35; P = 0.2). An earlier onset of menopause in hormone-treated women was associated with higher VAChT indexes in the anterior cingulate (rho = -0.56; P = 0.02) and posterior cingulate (rho = -0.63; P = 0.01). The opposite was found in the posterior cingulate of women not treated with hormones (rho = 0.58; P = 0.04). Women treated with estrogen alone also showed higher VAChT indexes than women treated with estrogen and progestin in the posterior cingulate cortex (by Mann-Whitney U test: z = 2.42; P = 0.015). Although an overall effect of postmenopausal hormone therapy was not found, associations between an index of cortical cholinergic terminal concentrations and the length of hormonal replacement suggest that hormone therapy may influence the survival or plasticity of these cells in postmenopausal women. The data also suggest possible differential effects of estrogen and estrogen with progestin treatments in brain areas critical for cognitive processing.

Aged↗
PubMed2001

Evolutionary dynamics of the human immunoglobulin kappa locus and the germline repertoire of the Vkappa genes.

We have determined the entire nucleotide sequence of the human immunoglobulin kappa locus, comprising a total of 1,010,706 nucleotides. The 76 Vkappa genes found by a hybridization-based approach and their classification in 7 families were confirmed. A Vkappa orphon located near the locus was also sequenced. In addition, we identified 55 novel Vkappa relics and truncated pseudogenes, which establish 5 new families. Among these 132 Vkappa genes, 46 have open reading frames. According to the databases and the literature, 32 unique Vkappa genes and 5 identical gene pairs form VJ-joints, 27 unique genes and 4 gene pairs are transcribed, and 25 unique genes and 4 gene pairs produce functional proteins. The Vkappa gene locus contains a 360-kb inverted duplication, which harbors 118 Vkappa genes. A comparison of the duplicated Vkappa genes suggests positive selection on the complementarity-determining regions of the duplicated genes by point mutations. The entire duplication unit was divided into 13 blocks, each of which has its distinct nucleotide sequence identity to its duplication counterpart (98.1 - 99.9 %). An inversion-mediated mechanism is suggested to generate the high-homology blocks. Based on the homology blocks and the mutation rates, the inverted duplication is assumed to have taken place approximately 5 million years ago. An orphon Vkappa gene near the kappa locus and a cluster of five Vkappa orphons on chromosome 22 have no counterparts within the kappa locus. This suggests possible mechanisms of the transposition of orphon Vkappa genes.

Base Composition↗
PubMed2001

Statistical brain mapping of 18F-FDG PET in Alzheimer's disease: validation of anatomic standardization for atrophied brains.

UNLABELLED: Despite the increased use of statistical mapping to detect brain functional changes in Alzheimer's disease (AD), potential artifacts introduced by stereotactic anatomic standardization of atrophied brains have not been examined carefully. We investigated the effects of anatomic standardization by Statistical Parametric Mapping (SPM) and NEUROSTAT. METHODS: First, 10 AD patients and 10 age-matched healthy volunteers underwent 18F-FDG brain PET imaging. Each image set was standardized to a stereotactic brain template using SPM or NEUROSTAT, followed by pixel normalization to the global or cerebellar activity. Within-group comparisons of standardized image sets by each method and a between-group comparison of healthy volunteers and AD patients were performed using the statistical analysis routines of SPM. Second, simulated PET image sets were generated from segmented MR image sets of 5 healthy volunteers and 5 AD patients. Using the anatomic standardization parameters estimated on the simulated image sets, original gray matter MR image sets were transformed to the stereotactic coordinate system. Between-group subtraction analyses of the transformed gray matter image sets between healthy volunteers and AD groups were performed to examine the accuracy of cortical gray matter matching. RESULTS: Between-group comparison by SPM or NEUROSTAT showed generally similar areas of hypometabolism in bilateral temporoparietal, posterior cingulate, and left frontal cortices. Both methods showed possible deformation artifacts in the anterior part of the corpus callosum. The localization of the peak hypometabolism varied considerably between the two methods when global normalization was applied. The use of a common brain template for standardization resulted in asymmetric differences in cortical margins, indicating systematic differences in the deformation algorithms. The realistic simulation study revealed gray matter mismatches to be 20% greater with SPM than with NEUROSTAT. CONCLUSION: Although different statistical mapping methods may yield grossly similar patterns of hypometabolism in AD, the extent, severity, and peak location of metabolic changes can be inconsistent. Deformation accuracy appears to be more prone to atrophy. These limitations need to be considered carefully in the application and interpretation of brain mapping analysis in atrophied brains.

Aged↗
PubMed2001

Familial Parkinson's disease. Alpha-synuclein and parkin.

We have reviewed recent progress in establishing the function of alpha-synuclein and parkin in relation to nigral degeneration in autosomal dominant and autosomal recessive PD. Mutations of alpha-synuclein (Ala53Thr and Ala30Pro) cause a form of autosomal dominant PD with early onset. Parkin is a novel protein expressed in the cytoplasm, including the terminal regions and Golgi apparatus. Mutations of parkin cause a form of autosomal recessive young-onset PD (ARJP). Both proteins appear to be associated with fast axonal transport. In addition, in sporadic PD, normal alpha-synuclein shows an increased tendency to self-aggregate. Thus, altered axonal transport of presynaptic proteins appears to play a crucial role in neurodegeneration in PD.

Humans↗
PubMed2000

Nicotine effects on regional cerebral blood flow in awake, resting tobacco smokers.

The hypothesis for this research was that regional cerebral blood flow (rCBF) would increase following nasal nicotine administration to overnight abstinent tobacco smokers in relationship to the known brain distribution of nicotinic cholinergic receptors (nAChRs). Nine male and nine female healthy adult smokers were studied. They abstained overnight from tobacco products for 10 or more hours prior to study the next morning. Nicotine nasal spray was given in doses of 1-2.5 mg total with half in each nostril while the subject was awake and resting in a supine position. Oleoresin of pepper solution in a similar volume was used as an active placebo to control for the irritating effects of nicotine. Both substances were given single blind to the subjects. Positron emission tomography (PET) with H(2)(15)O was used to measure rCBF. The data from each subject volunteer were normalized to global activity to better assess regional brain changes. Both nasal nicotine and pepper spray produced similar increases in CBF in somesthetic area II, consistent with the irritant effects of both substances. The mean rCBF effects of nasal pepper were subtracted from those of nasal nicotine to determine the actions of nicotine alone. The latter produced increases in rCBF in the thalamus, pons, Brodman area 17 of the visual cortex, and cerebellum. Some brain areas that contain a large number of nAChRs, such as the thalamus, showed an increase in CBF. Other areas that have few nAChRs, such as the cerebellum, also showed an increase in relative CBF. The hippocampal/parahippocampal areas showed greater regional decreases (left) and lesser increases (right) in CBF that correlated with the increase in plasma arterial nicotine concentrations. The results obtained indicate complex primary and secondary effects of nicotine in which only some regional brain CBF changes correlate with the known distribution of nAChR. No gender differences were noted.

Administration, Intranasal↗
PubMed2000

Cloning and characterization of a putative human glycerol 3-phosphate permease gene (SLC37A1 or G3PP) on 21q22.3: mutation analysis in two candidate phenotypes, DFNB10 and a glycerol kinase deficiency.

Using multiple exons trapped from human chromosome 21 (HC21)-specific cosmids with homology to a putative Arabidopsis thaliana glycerol 3-phosphate permease, we have determined the full-length cDNA sequence of a novel HC21 gene encoding a putative sugar-phosphate transporter (HGMW-approved symbol SLC37A1, aka G3PP). The predicted protein has 12 putative transmembrane domains and is also highly homologous to bacterial glpT proteins. The transcript was precisely mapped to 21q22.3 between D21S49 and D21S113. Comparison of the SLC37A1 cDNA to genomic sequence revealed that the gene encompasses 82 kb, and it is split into 19 coding exons and 7 untranslated exons, which are alternatively spliced in a complex and tissue-specific manner. Glycerol 3-phosphate (G3P) is produced by glycerol kinase (GK) and is found in several biochemical pathways in different cellular compartments, such as the glycerol phosphate shuttle and glycerophospholipid synthesis. Thus SLC37A1 mutations may cause a phenotype similar to GK deficiency. Mutational analyses of SLC37A1 in seven patients with no mutations in the GK gene and low GK activity revealed only nonpathogenetic sequence variants, excluding SLC37A1 as the gene for the phenotype in these patients. SLC37A1 maps in the refined critical region of the autosomal recessive deafness locus, DFNB10, on 21q22.3. Mutation analyses also excluded SLC37A1 as the gene for DFNB10.

Amino Acid Sequence↗
PubMed2000

Myocilin expression in the astrocytes of the optic nerve head.

We investigated the expression of myocilin in the optic nerve head of porcine eyes by Western blotting and immunohistochemical staining. Myocilin was localized in the nucleus, centrosome, glial filament, mitochondria, and some parts of the cell membranes of the astrocytes. Myocilin was also detected at the edge-feet portion of the processes of astrocytes adjacent to the inner limiting membrane and blood vessel wall. The astrocytes are the major cell population in the optic nerve head, contributing to the architecture of the nerve axon and blood vessels. Therefore, myocilin gene mutation and change of myocilin protein are likely to affect the architecture of the optic nerve head and induce various forms of glaucomatous optic nerve damage.

Animals↗
PubMed2000

Propagation and maintenance of the 119 human immunoglobulin Vlambda genes and pseudogenes during evolution.

We previously determined a contiguous 1,025,415-nucleotide sequence of the entire human immunoglobulin lambda gene locus, in which a total of 36 potentially functional Vlambda genes and 33 pseudogenes were localized. We also identified many more incomplete Vlambda genes to be characterized further. Some of these possessed only a slight sequence homology with the known Vlambda genes, and others possessed a high homology but had severely truncated coding regions. Here, we made extensive characterization of 50 new Vlambda pseudogenes, totaling 119 gene segments in the Vlambda gene locus. Of these 119 Vlambda genes, 118 were localized within the five Vlambda gene-rich clusters that we previously defined. Two of these novel Vlambda pseudogenes possessed the opposite transcriptional polarity to all the other Vlambda genes. The present comprehensive analysis of 119 Vlambda genes validated our previous classification of Vlambda genes and provided a basis for a possible mechanism by which a large number of Vlambda pseudogenes were propagated and maintained as a particular locus during evolution.

Base Sequence↗
PubMed2000

Refined localization of autosomal recessive nonsyndromic deafness DFNB10 locus using 34 novel microsatellite markers, genomic structure, and exclusion of six known genes in the region.

An autosomal recessive nonsyndromic deafness locus, DFNB10, was previously localized to a 12-cM region near the telomere of chromosome 21 (21q22.3). This locus was discovered in a large, consanguineous Palestinian family. We have identified and ordered a total of 50 polymorphic microsatellite markers in 21q22.3, comprising 16 published and 34 new markers, precisely mapped and ordered on BAC/cosmid contigs. Using these microsatellite markers, the locus for DFNB10 has been refined to an area of less than 1 Mb between markers 1016E7.CA60 and 1151C12.GT45. Six previously published cDNAs were mapped to this critical region, and their genomic structures were determined to facilitate mutation analysis in DFNB10. All six genes in this region (in order from centromere to telomere: White/ABCG1, TFF3, TFF2, TFF1, PDE9A, and NDUVF3) have been screened and eliminated as candidates for DFNB10. The new microsatellite markers and single nucleotide polymorphisms identified in this study should enable the refined mapping of other genetic diseases that map to 21q22.3. In addition, the critical region for DFNB10 has been reduced to a size amenable to an intensive positional cloning effort.

Chromosome Mapping↗