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PubMed2004

Electroanatomic versus fluoroscopic mapping for catheter ablation procedures: a prospective randomized study.

INTRODUCTION: The aim of this prospective randomized study was to compare the routine use of electroanatomic imaging (CARTO) with that of conventional fluoroscopically guided activation mapping (conventional) in an unselected population referred for catheter ablation. We sought to compare the two approaches with respect to procedure outcome and duration, radiation exposure, and cost. METHODS AND RESULTS: All patients undergoing catheter ablation (with the exception of complete AV nodal ablation) were prospectively randomized to either a CARTO or conventional procedure for mapping and ablation. One hundred two patients were randomized. Acute procedural success was similar with either strategy (CARTO vs conventional 43/47 vs 51/55, P > 0.5), as was procedure duration (144 [58] vs 125 [48] min, P = 0.07 (mean [SD]). CARTO was associated with a substantial reduction in fluoroscopy time (9.3 [7.6] vs 28.8 [19.5] min, P < 0.001) and radiation dose (6.2 [6.1] vs 20.8 [32.7] Gray, P = 0.003). CARTO cases used fewer catheters (2.5 [0.7] vs 4.4 [1.1], P < 0.001), but catheter costs were higher (13.8 vs 9.3 units, P < 0.001, where one unit is equivalent to the cost of a nonsteerable quadripolar catheter). CONCLUSION: For all catheter ablation procedures, even when a center's "learning curve" for CARTO is included, procedure duration and outcome are similar for CARTO and conventional procedures. CARTO is associated with drastically reduced fluoroscopy time and radiation dose. Although fewer catheters are used with CARTO, catheter costs remain higher.

Adolescent↗
PubMed1993

Using mitotic recombinant mutant clonal lymphocytes for physical mapping of polymorphic loci on the short arm of human chromosome 6.

Immunoselection has been used to identify human lymphocytes that have undergone spontaneous mutation resulting in the loss of expression of one of the codominant HLA-A alleles. Approximately 35% of such mutations are the consequence of mitotic recombination events. Mitotic recombination is the result of nonsister chromatid exchange that leaves the mutated cell homozygous for all loci distal to the crossover point. The location of the crossover has been regionalized for 99 independently derived mutant lymphocyte clones by identification of their loss or retention of heterozygosity at seven reference polymorphic loci on chromosome 6. If a polymorphic locus of unknown map position is studied in clones from this ordered set of mitotic recombinants, and clones that display loss of heterozygosity and retention of heterozygosity of the locus are observed, then the map position of the locus is between the appropriate reference loci of the ordered set. The newly mapped locus becomes a reference locus in turn. In this way the mitotic recombinant mutant clones can be used to generate an ordered set of crossover points with a theoretical resolution limited only by the number of mutants generated. In this paper such a set of mutants is used to refine or confirm the map position of eight polymorphic loci on chromosome 6.

Chromosome Mapping↗
PubMed1997

Value of simulated body surface potential maps as templates in localizing sites of ectopic activation for radiofrequency ablation.

Body surface potential maps recorded during catheter pace mapping can facilitate the localization of the site of origin of ventricular tachycardia. In this study, we investigated the value of a realistic computer model of the human ventricular myocardium in generating body surface potential maps as templates for identifying sites of ectopic activation. Our model features an anatomically accurate geometry and an anisotropy due to transmural fibre rotation, that were reconstructed with a spatial resolution of 0.5 mm. It simulates the electrotonic interactions of cardiac cells by solving a nonlinear parabolic partial differential equation, but it behaves as a cellular automaton when the transmembrane potential exceeds the threshold value. We successfully validated our model by comparing the simulated activation sequences--described by isochronal maps, epicardial potential maps and body surface potential maps--with the measured sequences of epicardial and body surface maps reported in the literature. By systematically pacing the left ventricular and right ventricular endocardial surfaces in our ventricular model, we generated a database of 155 QRS-integral maps, which provides a high-resolution reference frame for localizing distinct endocardial pacing sites. This database promises to be a useful tool in improving the performance of catheter pace mapping used in combination with body surface potential mapping. Overall, the results demonstrate that our computer model of the human ventricular myocardium is well suited for complementing a database of QRS-integral maps obtained during clinical pace mapping and can help enhance the efficacy of the ablative treatment of ventricular arrhythmias.

Anisotropy↗
PubMed1994

The mouse congenital polycystic kidney (cpk) locus maps within 1.3 cM of the chromosome 12 marker D12Nyu2.

The mouse congenital polycystic kidney (cpk) mutation causes bilateral cystic dilatation of the renal collecting tubules and leads to rapidly progressive renal insufficiency in affected homozygotes. The phenotype of the cpk/cpk mutants closely resembles that of human autosomal recessive polycystic kidney disease (ARPKD). Previously, we have reported that the cpk locus maps close to D12Nyu2 on Chromosome (Chr) 12. To determine the cpk map location more precisely, we have extended our previous studies using additional progeny and additional markers of proximal Chr 12. These recent studies position cpk within 1.3 cM of D12Nyu2, closely flanked by (Odc, D12Mit10) and (Tpo, D12Mit12). Our data support an ordered array of seven DNA markers that will provide reference points for building a physical map of the Chr 12 region centered on cpk. Moreover, these data establish that cpk lies within a linkage group that is conserved between mouse Chr 12 and human chr 2p24-2p25. This assignment to a region of homology will facilitate human linkage analyses to determine whether mouse cpk and human ARPKD are mutations of homologous genes.

Animals↗
PubMed2000

Mapping toxin exposure risk due to children's play: a case study.

During the 1920's and 1930's, a Niagara County, New York residential community, Belden Center, developed in tandem with two adjacent toxic waste disposal sites. During the period that they were in use, both sites were classified as public health hazards. Particularly between 1944 and 1979, as toxins were deposited, neighborhood children swam and played throughout the industrial waste sites. By reference to a large-scale map of the dumps, present residents described locations and types of play during their childhood. Assuming that a child would play away from home between 8 and 19 years of age, this allowed identification of cohorts that used the sites during different periods. An outcome map showing sites, dates, and types of play is the primary product of this investigation. More boys than girls played in the dumpsites, and we identified a subsample that did not use them for play. We conclude that children's play should be considered a major source of risk where communities lie next to toxic waste sites.

Activities of Daily Living↗
PubMed1997

Exclusion of the phosphatidylinositol-specific phospholipase C beta 3 (PLC beta 3) gene as candidate for the multiple endocrine neoplasia type 1 (MEN 1) gene.

Multiple endocrine neoplasia type 1 (MEN 1) is inherited as an autosomal dominant disorder, characterized by hyperplasia and neoplasia in several endocrine organs. The MEN 1 gene, which is most probably a tumor suppressor gene, has been localized to a 900-kb region on chromosome 11q13. The human phosphatidylinositol-specific phospholipase C beta 3 (PLC beta 3) gene, which is located within this region, was considered to be a good candidate for the MEN 1 gene. In this study, the structure and expression of the PLC beta 3 gene in MEN 1 patients were investigated in more detail, to determine its potential role in MEN 1 tumorigenesis. Southern blot analysis, using blood and tumor DNA from affected persons from seven different MEN 1 families, did not reveal structural abnormalities in the PLC beta 3 gene. To detect possible point mutations, or other small structural aberrations, direct sequencing of PLC beta 3 cDNAs from two affected persons from two different MEN 1 families was performed, but no MEN 1-specific abnormalities were revealed. Several common nucleotide sequence polymorphisms were detected in these cDNAs, proving that both alleles of the PLC beta 3 gene were expressed and analyzed. In conclusion, these results exclude the PLC beta 3 gene as a candidate gene for MEN 1.

Base Sequence↗
PubMed1991

Addition of MT, D16S10, D16S4, and D16S91 to the linkage map within 16q12.1-q22.1.

A 10-point genetic linkage map of the region 16q12.1 to 16q22.1 has been constructed using the CEPH reference families. Four loci, MT, D16S10, D16S91, and D16S4, not previously localized on a multipoint linkage map, were incorporated on the map presented here. The order of loci was cen-D16S39-MT, D16S65-D16S10-FRA16B-D16S38, D16S4, D16S91, D16S46-D16S47-HP-qter. The interval between D16S10 and 4D16S38 is 3.1 cM in males and 2.3 cM in females, and contains FRA16B. The cloning strategy for FRA16B will now be based on YAC walking from D16S10 and D16S38. The location of FRA16B between D16S10 and D16S38 provides a physical reference point for the multipoint linkage map on the short arm of chromosome 16.

Chromosome Mapping↗
PubMed1995

Human adenosine A1 receptor gene: systematic screening for DNA sequence variation and linkage mapping on chromosome 1q31-32.1 using a silent polymorphism in the coding region.

Adenosine is a major inhibitory neuromodulator in the central nervous system. One of the receptors mediating the central effects of adenosine is the adenosine A1 receptor. We performed a systematic mutation scan of the coding region of the adenosine A1 receptor gene to explore its variability in the general population. Investigating 40 unrelated healthy subjects by single-strand conformation analysis no sequence changes of likely functional relevance were observed. We detected, however, a frequent T to G substitution at nucleotide position 716 which constitutes the first variant described in an adenosine receptor gene. It was used for fine scale linkage mapping of the A1 gene. Employing a polymerase-chain-reaction-based restriction assay, we genotyped 7 CEPH families (Centre d'Etude du Polymorphisme Humaine) and mapped the receptor in a gene cluster around the renin gene on chromosome 1q31-32.1. In addition, we utilized the 716T/G polymorphism to demonstrate biallelic expression of the adenosine A1 receptor gene in adult human brain.

Adult↗
PubMed1995

Genetic differences in recombination frequency in the pig (Sus scrofa).

A comparison has been performed on 3 recently published linkage maps of the pig, hereafter designated as the American (A), European (E), and Swedish (S) maps. The cumulated distances between common markers in these 3 maps were in the ratio 1.00 (A):0.88 (E):0.77 (S), in keeping with the ratio of the percentages of domestic genome in the reference families used to build the corresponding maps, i.e., 1.00 (A):0.81 (E):0.50 (S). From further recombination frequencies reported in wild boars (in the S report), the wild pig genome length (in centimorgans) is expected to represent 66% of the domestic pig genome length. These observations tend to confirm a general result of Burt and Bell (Nature (London), 326: 803-805 (1987)), showing higher chiasma frequencies in domestic mammalian species compared with wild species. Consequences for mapping studies are discussed.

Animals↗
PubMed2000

Multipoint genetic mapping with uniparental disomy data.

Uniparental disomy (UPD) refers to the presence of two copies of a chromosome from one parent and none from the other parent. In genetic studies of UPDs, many genetic markers are usually used to identify the stage of nondisjunction that leads to UPD and to uncover the associated unusual patterns of recombinations. However, genetic information in such data has not been fully utilized because of the limitations of the existing statistical methods for UPD data. In the present article, we develop a multilocus statistical approach that has the advantages of being able to simultaneously consider all genetic markers for all individuals in the same analysis and to allow general models for the crossover process to incorporate crossover interference. In particular, for a general crossover-process model that assumes only that there exists in each interval at most one crossover, we describe how to use the expectation-maximization algorithm to examine the probability distribution of the recombination events underlying meioses leading to UPD. We can also use this flexible approach to create genetic maps based on UPD data and to inspect recombination differences between meioses exhibiting UPD and normal meioses. The proposed method has been implemented in a computer program, and we illustrate the proposed approach through its application to a set of UPD15 data.

Algorithms↗
PubMed1994

The Sjögren-Larsson syndrome gene is close to D17S805 as determined by linkage analysis and allelic association.

Sjögren-Larsson Syndrome (SLS) is characterized by congenital ichthyosis, spastic dior tetraplegia and mental retardation. It is an autosomal recessive trait that is frequent in the northern part of Sweden. Based on linkage analysis and allelic association, the disorder has now been mapped to chromosome 17. Meiotic recombinations suggest that the gene is flanked by D17S805 on the centromeric and D17S783, D17S959, D17S842 and D17S925 on the telomeric side. These markers map to the same location in reference pedigrees. Strong allelic association (chi-square 60.28, p < 0.0003) to D17S805 suggests that the mutation is located close to this marker.

Alleles↗
PubMed1996

Systematic screening for mutations in the human serotonin-2A (5-HT2A) receptor gene: identification of two naturally occurring receptor variants and association analysis in schizophrenia.

A statistically significant association between a silent mutation (102T/C) in the serotonin-2A (5-HT2A) receptor gene and schizophrenia has recently been reported in a sample of Japanese patients and healthy controls. This finding suggests that genetic predisposition to schizophrenia may be affected by a functional 5-HT2A receptor variant that is in linkage disequilibrium with 102T/C. In the present study, we have sought to identify genetic variation in the 5-HT2A receptor gene by screening genomic DNA samples from 91 unrelated subjects comprising 45 patients with schizophrenia and 46 healthy controls by using single-strand conformation analysis. We have identified four nucleotide sequence variants. Two sequence changes would result in protein alterations: a substitution of threonine by asparagine at position 25 (Thr25Asn), and a substitution of histidine by tyrosine at position 452 (His452Tyr). In order to test for a possible contribution to the development of schizophrenia, we have determined allele frequencies in extended samples of unrelated patients and healthy controls. The two amino acid substitutions are found with similar frequencies in patients and controls, indicating that the presence of these variants is not causally related to the development of schizophrenia. However, the reported association of the non-coding polymorphism 102T/C with the disease has also been detected in our sample (P=0.041, odds ratio=1.28, 95% confidence interval 1.012-1.623).

Alleles↗
PubMed1995

Comparative analysis of mouse NotI linking clones with mouse and human genomic sequences and transcripts.

NotI cleavage sites are frequently associated with CpG islands that identify the 5' regulatory sites of functional genes in the genome. Therefore we analyzed a sample of 22 NotI linking clones prepared from mouse brain DNA, to determine whether these mouse NotI site associated clones could be used for comparative analysis of mouse and human genomes by cross-reaction with both mouse and human genomic DNA and RNA in Southern and Northern hybridization. We further examined whether we could establish the identity of these clones with known genes by comparing the nucleotide sequences surrounding the NotI site with the GenBank database. We observed that 70% of the clones cross-hybridized with human DNA and that 4 of 11 tested clones (36%) detected a transcript in human HeLa cells RNA whereas 73% clones (8/11) detected transcripts in mouse RNAs from one or more organs. Single pass sequence analysis was successful on 16 of 19 clones. The GC content in these sequence was very high (48.8% to 73.8%) suggesting that 12 of 16 sequenced clones contained a CpG island. Three out of 19 clones showed significant similarity with previously analyzed mouse gene sequences in GenBank, including the mouse rRNA gene family, cathepsin and the scip POU-domain genes. In addition, two sequences showed significant similarity to the human and rabbit protein phosphatase 2A-beta subunit and the human transforming growth factor-beta. Thus, 5 of 16 clones showed homology with identified genes. These results and the recent work of using RLGS methods for genetic mapping indicate that NotI linking clones can be used to efficiently cross reference a comparative analysis of the mouse and human genomic maps.

Animals↗
PubMed2005

Virtual screening for anti-HIV-1 RT and anti-HIV-1 PR inhibitors from the Thai medicinal plants database: a combined docking with neural networks approach.

The virtual screening approach for docking small molecules into a known protein structure is a powerful tool for drug design. In this work, a combined docking and neural network approach, using a self-organizing map, has been developed and applied to screen anti-HIV-1 inhibitors for two targets, HIV-1 RT and HIV-1 PR, from active compounds available in the Thai Medicinal Plants Database. Based on nevirapine and calanolide A as reference structures in the HIV-1 RT binding site and XK-263 in the HIV-1 PR binding site, 2,684 compounds in the database were docked into the target enzymes. Self-organizing maps were then generated with respect to three types of pharmacophoric groups. The map of the reference structures were then superimposed on the feature maps of all screened compounds. Only the structures having similar features to the reference compounds were accepted. By using the SOMs, the number of candidates for HIV-1 RT was reduced to six and nine compounds consistent with nevirapine and calanolide A, respectively, as references. For the HIV-1 PR target, there are 135 screened compounds showed good agreement with the XK-263 feature map. These screened compounds will be further tested for their HIV-1 inhibitory affinities. The obtained results indicate that this combined method is clearly helpful to perform the successive screening and to reduce the analyzing step from AutoDock and scoring procedure.

Anti-HIV Agents↗
PubMed2026

Characterizing features of the genetic architecture underlying autism from a multi-ancestry perspective.

Autism spectrum disorder (ASD; MIM 209850) is reported to vary globally from 0.01% in East Asian populations to 4.36% in certain Australian cohorts. Despite high heritability estimates (61-94%), the genetic architecture underlying ASD susceptibility remains poorly characterized across diverse populations, as most genomic studies have initially focused on individuals of European ancestry. To investigate ancestry-specific genetic contributions to ASD, we analyzed whole-genome sequencing data from three independent ASD cohorts. We identified admixed ASD probands (n&#x2009;=&#x2009;1 033) and ancestry-matched controls (n&#x2009;=&#x2009;1 033) and performed admixture mapping (AM). AM using five continental reference populations (European, African, East Asian, South Asian, and Native American) identified five ancestry-specific ASD-susceptibility loci, including one African-related locus at 1p21.2 near S1PR1 and four Native American-associated loci at chromosome 11q13.4. Three of these latter loci were contiguous and encompassed genes previously implicated in ASD, notably SHANK2 and DHCR7, with fine-mapping identifying a significantly associated variant between the two genes (rs77695321; P&#x2009;=&#x2009;1.52 &#xd7; 10&#x207b;&#x2077;). The fourth Native American-associated signal at 11q13.4 overlapped the folate receptor genes FOLR1 and FOLR3, with fine-mapping identifying a genome-wide significant variant (rs7950807; P&#x2009;=&#x2009;5.21 &#xd7; 10&#x207b;&#x2078;). A secondary admixture mapping analysis restricted to Latin American individuals, incorporating 6 487 Brazilian controls, identified 16 additional ancestry-specific loci across seven genomic regions.

Journal Article↗
PubMed2002

Imaging cortical association tracts in the human brain using diffusion-tensor-based axonal tracking.

Diffusion-tensor fiber tracking was used to identify the cores of several long-association fibers, including the anterior (ATR) and posterior (PTR) thalamic radiations, and the uncinate (UNC), superior longitudinal (SLF), inferior longitudinal (ILF), and inferior fronto-occipital (IFO) fasciculi. Tracking results were compared to existing anatomical knowledge, and showed good qualitative agreement. Guidelines were developed to reproducibly track these fibers in vivo. The interindividual variability of these reconstructions was assessed in a common spatial reference frame (Talairach space) using probabilistic mapping. As a first illustration of this technical capability, a reduction in brain connectivity in a patient with a childhood neurodegenerative disease (X-linked adrenoleukodystrophy) was demonstrated.

Adrenoleukodystrophy↗
PubMed1997

New diallelic markers in the HLA region of chromosome 6.

Diallelic polymorphisms have been identified in the HLA-H gene and the ZNF192 gene located about 2 megabases centromeric to HLA-H. The three polymorphic sites in HLA-H together with the two hemochromatosis mutations in this gene give rise to 8 different haplotypes. The three polymorphic sites in ZNF192 give rise to 4 different haplotypes. The haplotypes in HLA-H are in complete linkage disequilibrium with the two common mutations in that gene, 845A (C282Y) and 187G (H63D). The 845A mutation is in weak linkage disequilibrium with the ZNF192 polymorphisms and the 187G mutation appears to be in equilibrium with this polymorphism. The 187G mutation therefore appears to be the older of the two HLA-H mutations.

Alleles↗