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PubMed1995

Body surface Laplacian electrocardiographic mapping--a review.

It is of great importance and significance to be able to noninvasively map spatially distributed cardiac electrical activity from body surface electrical recordings. The standard electrocardiographic monitoring techniques provide little spatial information regarding cardiac electrical activity. Recently, a new approach-body surface Laplacian electrocardiographic mapping-has been aggressively pursued to provide high-resolution spatial mapping of cardiac electrical activity. The fundamental innovation is the measurement of the Laplacian electrocardiogram distribution over the body surface. The body surface Laplacian electrocardiographic maps have been shown to provide enhanced ability to map multiple spatially separate cardiac bioelectric sources. This article reviews the theoretical and experimental aspects of this emerging mapping technique. First of all, the paper briefly reviews the historical development of body surface mapping and inverse solutions for mapping the distributed cardiac electrical activity. Then the paper reviews the theoretical basis of body surface Laplacian mapping and the biophysical interpretation of body surface Laplacian signals, as well as technical consideration of the Laplacian recording and instrumentation. Investigations of body surface Laplacian maps in computer models and a physical tank model, as well as physiological studies are also reviewed.

Animals↗
PubMed1999

The effect of the Müller-Lyer illusion on map reading.

One important reason for studying visual illusions is that they can influence real-world perception as people interact with human-made displays. Three experiments examined how the Müller-Lyer illusion affects distance judgments and decision-making in the complex graphical context of a map by having subjects estimate the lengths of road segment lines framed by inward-going or outward-going wings in actual maps, in control displays that had the map context removed, and in simulated maps. The experiments showed that (1) outward-going wings led to higher distance estimates than did inward-going wings to the same extent both with and without the map context, (2) decisions based on distances determined from maps were affected by Müller-Lyer elements in the maps, and (3) map readers' measurement behavior influenced the effect of the Müller-Lyer elements in maps. The discussion focuses on how certain display manipulations and task manipulations affect the Müller-Lyer illusion. In addition, the discussion addresses the instances in which using a map might be affected by misestimation due to Müller-Lyer elements.

Adult↗
PubMed1999

Identifying and mapping novel retinal-expressed ESTs from humans.

PURPOSE: The goal of this study was to develop efficient methods to identify tissue-specific expressed sequence tags (ESTs) and to map their locations in the human genome. Through a combination of database analysis and laboratory investigation, unique retina-specific ESTs were identified and mapped as candidate genes for inherited retinal diseases. METHODS: DNA sequences from retina-specific EST clusters were obtained from the TIGR Human Gene Index Database. Further processing of the EST sequence data was necessary to ensure that each EST cluster represented a novel, non-redundant mapping candidate. Processing involved screening for homologies to known genes and proteins using BLAST, excluding known human gene sequences and repeat sequences, and developing primers for PCR amplification of the gene encoding each cDNA cluster from genomic DNA. The EST clusters were mapped using the GeneBridge 4.0 Radiation Hybrid Mapping Panel with standard PCR conditions. RESULTS: A total of 83 retinal-expressed EST clusters were examined as potential novel, non-redundant mapping candidates. Fifty-five clusters were mapped successfully and their locations compared to the locations of known retinal disease genes. Fourteen EST clusters localize to candidate regions for inherited retinal diseases. CONCLUSIONS: This pilot study developed methodology for mapping uniquely expressed retinal ESTs and for identifying potential candidate genes for inherited retinal disorders. Despite the overall success, several complicating factors contributed to the high failure rate (33%) for mapping EST-clustered sequences. These include redundancy in the sequence data, widely dispersed sequences, ambiguous nucleotides within the sequences, the possibility of amplifying through introns and the presence of repetitive elements within the sequence. However, the combination of database analysis and laboratory mapping is a powerful method for identification of candidate genes for inherited diseases.

Chromosome Mapping↗
PubMed2000

Mapping functionally related regions of brain with functional connectivity MR imaging.

BACKGROUND AND PURPOSE: In subjects who are performing no prescribed cognitive task, functional connectivity mapped with MR imaging (fcMRI) shows regions with synchronous fluctuations of cerebral blood flow. When specific tasks are performed, functional MR imaging (fMRI) can map locations in which regional cerebral blood flow increases synchronously with the performance of the task. We tested the hypothesis that fcMRI maps, based on the synchrony of low-frequency blood flow fluctuations, identify brain regions that show activation on fMRI maps of sensorimotor, visual, language, and auditory tasks. METHODS: In four volunteers, task-activation fMRI and functional connectivity (resting-state) fcMRI data were acquired. A small region of interest (in an area that showed maximal task activation) was chosen, and the correlation coefficient of the corresponding resting-state signal with the signal of all other voxels in the resting data set was calculated. The correlation coefficient was decomposed into frequency components and its distribution determined for each fcMRI map. The fcMRI maps were compared with the fMRI maps. RESULTS: For each task, fcMRI maps based on one to four seed voxel(s) produced clusters of voxels in regions of eloquent cortex. For each fMRI map a closely corresponding fcMRI map was obtained. The frequencies that predominated in the cross-correlation coefficients for the functionally related regions were below 0.1 Hz. CONCLUSION: Functionally related brain regions can be identified by means of their synchronous slow fluctuations in signal intensity. Such blood flow synchrony can be detected in sensorimotor areas, expressive and receptive language regions, and the visual cortex by fcMRI. Regions identified by the slow synchronous fluctuations are similar to those activated by motor, language, or visual tasks.

Adult↗
PubMed1991

Mapping of human chromosome Xq28 by two-color fluorescence in situ hybridization of DNA sequences to interphase cell nuclei.

We have used the proximity of probe hybridization sites in interphase chromatin to derive the order of DNA sequences in a 2-3-Mbp region of human chromosome Xq28. The map generated bridges the results of genetic and pulsed-field gel electrophoresis mapping to produce a more complete map of Xq28 than possible with either of these other techniques alone. Two-color fluorescence in situ hybridization (FISH) was used to detect the positions of two or more probes in G1 male interphase nuclei. We show that cosmids that are 50 kbp to 2-3 Mbp apart can be ordered rapidly with two alternative approaches: (1) by comparing the average measured distance between two probes and (2) simply by scoring the order of red and green fluorescent dots after detection of three or more probes with two fluorochromes. The validity of these approaches is demonstrated using five cosmids from a region spanning approximately 800 kbp that includes the factor VIII (F8), glucose-6-phosphate dehydrogenase (G6PD), and color-vision pigment (CV) genes. The cosmid map derived from interphase mapping is consistent with the map determined by restriction-fragment analysis. The two interphase mapping approaches were then used (1) to orient the F8/CV cluster relative to two markers, c1A1 and st14c, which we show by metaphase mapping to be proximal to the F8/CV cluster, (2) to position st14c (DXS52) between c1A1 and F8, and (3) to orient the CV gene cluster relative to G6PD by using two CV-flanking cosmids, 18b41 and fr7. The probe order in Xq28 derived from interphase proximity is cen-c1A1-st14c-5'F8 (p624-p542-p625)-G6PD-18b41-3' green-green-red-fr7-tel. We also show that, to determine their order by using metaphase chromosomes, sequences must be at least 1 Mbp apart, an order of magnitude greater than required in interphase chromatin. The data show that FISH mapping is a simple way to order sequences separated by greater than or equal to 50 kbp for the construction of long-range maps of mammalian genomes.

Chromosome Mapping↗
PubMed1988

Computed electroencephalographic topographic brain mapping. A new and accurate monitor of cerebral circulation and function for patients having carotid endarterectomy.

To determine the usefulness of computed electroencephalographic (EEG) topographic (CET) brain mapping to monitor neurologic function during carotid endarterectomy (CEA), 46 consecutive patients having CEA were monitored preoperatively, intraoperatively, and immediately postoperatively by CET brain mapping and simultaneous 16-lead EEG. Preoperative studies revealed that 7 of 16 asymptomatic patients, 5 of 11 patients with amaurosis fugax, and 8 of 12 patients with transient ischemic attacks (TIAs) had abnormal CET brain mapping suggestive of previous subclinical stroke. EEG was abnormal in only 8 of the 20 patients with abnormal CET brain mapping. Intraoperatively during carotid cross-clamping, ischemic changes were seen on CET brain mapping in 23 patients whereas EEG detected these changes in only 13 patients. Ischemic changes detected by intraoperative CET brain mapping were more likely to occur in patients with previous stroke (six of seven) than in patients without previous stroke (17 of 39), p less than 0.05. Patients with changes detected by intraoperative CET brain mapping had an average carotid back-pressure of 38 mm Hg, in contrast to 57 mm Hg for patients without CET brain mapping changes, p less than 0.05. After endarterectomy, CET brain mapping revealed new ischemic changes in one patient who awoke with a mild stroke and in one patient who had TIAs and amaurosis fugax within 6 hours of surgery. We conclude that CET brain mapping is a sensitive, accurate, and useful noninvasive monitor of cerebral circulation and function for patients having CEA.(ABSTRACT TRUNCATED AT 250 WORDS)

Blindness↗
PubMed2004

Integration of multiple downstream signals determines the net effect of insulin on MAP kinase vs. PI 3'-kinase activation: potential role of insulin-stimulated H(2)O(2).

Cellular insulin stimulation generates a burst of H(2)O(2) that modulates protein-tyrosine phosphorylation in the insulin action pathway, in part by the inhibition of redox-sensitive protein-tyrosine phosphatases [J. Biol. Chem. 276 (2001) 21938]. Blocking the insulin-induced rise in H(2)O(2) with the NADPH oxidase inhibitor diphenyleneiodonium (DPI) strongly attenuated the activation of phosphatidylinositol 3' (PI 3')-kinase, Akt and GLUT4 translocation by insulin in 3T3-L1 adipocytes; however, under identical conditions, we observed a paradoxical increase in the activation of p42/p44 mitogen-activated protein (MAP) kinase. DPI inhibited the insulin-stimulated tyrosine phosphorylation of the insulin receptor and IRS-1/2, and also reduced the association of Grb2 with IRS-1, suggesting that the effect of DPI on MAP kinase activation occurred downstream of the IR and IRS proteins. DPI increased the insulin-stimulated phosphorylation of p42/p44 MAP kinase with no change in basal, and increased insulin-stimulated MAP kinase kinase (MEK) activity by a similar degree. DPI enhanced basal Grb2-Sos binding and reduced the effect of insulin to potentiate the dissociation of the Grb2-Sos complex, suggesting that the effect of DPI was mediated upstream of Raf-1. Cell treatment with dibutyryl cAMP significantly reduced the enhancement of MAP kinase activation in the presence of DPI. However, forskolin, acting in a PKA-independent manner, increased the insulin stimulation of MAP kinase and MEK, but fully abrogated the effect of DPI to enhance these insulin responses. PLCgamma inhibition with U73122 blocked the insulin stimulation of MAP kinase and MEK as well as the enhancing effect of DPI on these responses. PKC activation strongly stimulated MAP kinase and MEK activation, even in the presence of U73122, consistent with PKC acting downstream of PLCgamma. These data show that the insulin-stimulated oxidant signal differentially affects the two major downstream components of the insulin signaling pathway, PI 3'-kinase and MAP kinase, and cross-talk between insulin action, PLCgamma and, to a lesser extent, PKA modulates the net cellular effects of insulin-stimulated cellular H(2)O(2).

3T3-L1 Cells↗
PubMed2003

A high resolution physical and RH map of pig chromosome 6q1.2 and comparative analysis with human chromosome 19q13.1.

BACKGROUND: The generation of BAC/PAC contigs in targeted genome regions is a powerful method to establish high-resolution physical maps. In domestic animal species the generation of such contigs is typically initiated with the screening of libraries with probes derived from human genes that are expected to be located in the region of interest by comparative mapping. However, in many instances the available gene-derived probes are too far apart to allow the cloning of BAC/PAC contigs larger than a few hundred kb. High resolution physical mapping allows to estimate the sizes of gaps and to control the orientation of the individual sub-contigs, which helps to avoid errors during the assembly of smaller contigs into final Mb-sized contigs. The recently constructed porcine IMNpRH2 panel allowed us to use this approach for the construction of high-resolution physical maps of SSC 6q1.2. RESULTS: Two sequence-ready BAC/PAC contigs of the gene-rich region on porcine chromosome 6q1.2 (SSC 6q1.2) containing the RYRl gene were constructed. The two contigs spanned about 1.2 Mb and 2.0 Mb respectively. The construction of these contigs was monitored by the results provided by the mapping of 15 markers on the IMpRH(7000rad) and 35 markers on the IMNpRH2(12000rad) radiation hybrid panels. Analyses on the IMpRH panel allowed us to globally link and orientate preliminary smaller contigs, whereas analyses on the high resolution IMNpRH2 panel allowed us to finally identify the order of genes and markers. CONCLUSIONS: A framework map of 523 cR12000 was established covering the whole studied region. The order of markers on the framework 1000:1 RH map was found totally consistent with the data deduced from the contig map. The kb/cR ratio was very constant in the whole region, with an average value of 6.6 kb/cR. We estimate that the size of the remaining gap between the two contigs is of about 300 kb. The integrated physical and RH map of the investigated region on SSC 6q1.2 was used for a comparative analysis with respect to the syntenic regions on HSA 19q13.1 and MMU 7 and revealed a perfectly conserved gene order across the entire studied interval.

Animals↗
PubMed1994

Antisense MAP-2 oligonucleotides induce changes in microtubule assembly and neuritic elongation in pre-existing neurites of rat cortical neurons.

Microtubule-associated protein 2 (MAP-2) is an abundant component of the cytoskeleton present in dendrites and cell bodies of neurons of the CNS. To examine the biological function of MAP-2, two MAP-2 antisense (AS) oligonucleotides complementary to the 5' region of the rat MAP-2 cDNA were added to rat primary embryonic day 17-18 (E17-18) cultured cortical neurons 24 h after plating and neurite outgrowth and morphology studied. The treatment of primary cortical cultures with either of the two MAP-2 AS oligonucleotides resulted in decreased MAP-2 and reduction in the number of neuritic processes relative to the control or MAP-2 sense-treated cultures. By immunostaining and light microscopy the AS-treated neurons appeared smaller, more rounded, and less intensely stained for MAP-2 than the untreated or the MAP-2 sense-treated cultures. By electron microscopy disorganized microtubules and a reduction in the number of microtubules within neurites of the AS-treated cultures were observed. We conclude that MAP-2 continues to be required for microtubule spacing and stability within neurites once they have formed.

Animals↗
PubMed1995

Requirement of MAP kinase for differentiation of fibroblasts to adipocytes, for insulin activation of p90 S6 kinase and for insulin or serum stimulation of DNA synthesis.

A phosphorothioate-oligonucleotide-based antisense strategy for depleting MAP kinase was developed. The 17mer antisense probe, EAS 1, caused a potent and concentration-dependent decrease in the steady state expression of p42 and p44 MAP kinase in 3T3 L1 fibroblasts and adipocytes with submicromolar concentrations effective. Antisense EAS 1 elicited a dose-dependent inhibition of insulin- and serum-stimulated DNA synthesis. Elimination of p42 MAP kinase by > 95% and p44 MAP kinase to levels undetected blocked the ability of serum in 3T3 L1 fibroblasts and insulin in 3T3 L1 adipocytes to stimulate DNA synthesis by 87-95%. The differentiation of 3T3 L1 fibroblasts into adipocytes was prevented by 1 microM antisense EAS 1. The corresponding sense, scrambled or sense plus antisense EAS 1 phosphorothioate oligonucleotides did not deplete the p42 or p44 MAP kinase from either cell type, did not inhibit stimulation of DNA synthesis and did not interfere with differentiation. Two kinases on different MAP kinase activation pathways were not depleted by antisense EAS 1 whereas the ability of insulin to activate p90 S6 kinase was > 90% eliminated in 3T3 L1 adipocytes by 4.5 microM antisense EAS 1. In conclusion these results show that MAP kinase is required for insulin and serum stimulation of DNA synthesis, for insulin stimulation of p90 S6 kinase activity and for differentiation of 3T3 L1 cells. Moreover, the development of the antisense probe EAS 1 against a target sequence of p42 MAP kinase that is conserved in p44 MAP kinase and across a range of species provides a molecular tool of general applicability for further dissecting the precise targets and roles of MAP kinase.

3T3 Cells↗
PubMed1996

Comparison of linear and branched peptide forms (MAPs) in the induction of T helper responses to point-mutated ras immunogens.

The utility of multiple antigenic peptides (MAPs) for the induction of antibody and cellular immune responses in animal models has been demonstrated for a variety of peptide epitopes involved in human disease. However, little is known about immune responses to MAPs constructed with antigenic tumor epitopes, nor has peptide specificity in branched forms been addressed. A potentially important advantage of the MAP system over linear peptide immunogens for clinical applications is elimination of the need for a protein carrier with its associated toxicity and immunogenicity. Here, we examined cellular immune responses following in vivo administration of MAPs incorporating a 13-mer T helper epitope from point-mutated ras p21 (ras V12) and compared the potency of the responses to that of the linear peptide. The Gly --> Val mutation in position 12, which is associated with a range of human carcinomas, represents a useful system for evaluating the specificity of the immune response. In initial studies with the point-mutated linear peptide epitope, optimal in vitro proliferation responses were obtained following sc administration of the peptide in a squalane-containing adjuvant formulation. Comparative immunization studies using point-mutated MAPs bearing two, four, or eight branches were administered either in saline or in adjuvant. These studies showed that adjuvant was required for the induction of cellular immune responses using both linear and all three forms of branched peptides. Moreover, there was no apparent advantage of using any of the MAPs vs linear peptide when equivalent mass amounts were administered, i.e., the intensity of the immune response was no greater using any of the branched structures compared to the linear form. Specificity of the in vivo responses for both the linear and the MAP immunogens was demonstrated by the higher stimulation indices observed in vitro in the presence of the mutant ras V12 vs the normal ras G12 linear peptide. No apparent cellular immune response to the MAP core structure itself was observed. However, a nonspecific response to the two-branched MAP2G12 structure was observed in some assays, the nature of which is unknown at this time. This work represents the first reported investigation of a cellular immune response using MAP immunogens incorporating a tumor-specific peptide epitope and demonstrates that linear peptides are as efficient as three different MAP structures in the generation of specific T cell responses.

Adjuvants, Immunologic↗
PubMed2000

The relationship between calcium, MAP kinase, and DNA synthesis in the sea urchin egg at fertilization.

Fertilization releases the brake on the cell cycle and the egg completes meiosis and enters into S phase of the mitotic cell cycle. The MAP kinase pathway has been implicated in this process, but the precise role of MAP kinase in meiosis and the first mitotic cell cycle remains unknown and may differ according to species. Unlike the eggs of most animals, sea urchin eggs have completed meiosis prior to fertilization and are arrested at the pronuclear stage. Using both phosphorylation-state-specific antibodies and a MAP kinase activity assay, we observe that MAP kinase is phosphorylated and active in unfertilized sea urchin eggs and then dephosphorylated and inactivated by 15 min postinsemination. Further, Ca(2+) was both sufficient and necessary for this MAP kinase inactivation. Treatment of eggs with the Ca(2+) ionophore A23187 caused MAP kinase inactivation and triggered DNA synthesis. When the rise in intracellular Ca(2+) was inhibited by injection of a chelator, BAPTA or EGTA, the activity of MAP kinase remained high. Finally, inhibition of the MAP kinase signaling pathway by the specific MEK inhibitor PD98059 triggered DNA synthesis in unfertilized eggs. Thus, whenever MAP kinase activity is retained, DNA synthesis is inhibited while inactivation of MAP kinase correlates with initiation of DNA synthesis.

Animals↗
PubMed1995

Intercellular heterogeneity of early mitogenic events: cAMP generalizes the EGF effect on c-Fos protein appearance but not on MAP kinase phosphorylation and nuclear translocation in dog thyroid epithelial cells.

When quiescent dog thyroid epithelial cells in primary culture are stimulated for 48 h with thyrotropin (TSH), forskolin acting through cAMP, or with cAMP-independent mitogens including epidermal growth factor (EGF), hepatocyte growth factor (HGF), and a tumor promoting phorbol ester (TPA), only 30-60% of cells progress through the cell cycle. A more general growth response requires the combination of EGF and TSH or forskolin. In this study we ask whether this intercellular heterogeneity in mitogen sensitivity could depend on a similar heterogeneity at early stages of the mitogenic stimulation process, i.e., at the levels of p42/p44 MAP kinase nuclear translocation and c-Fos protein appearance. We used indirect immunofluorescence microscopy with photometric quantitation and corroborated data using Western blotting. We analyzed the double staining of c-Fos and p42/p44 MAP kinases, since the nuclear translocation of these MAP kinases has been suggested as a key step for the stimulation of c-fos transcription. (i) EGF and HGF induced c-Fos accumulation and MAP kinase translocation in variable fractions of the cell population that corresponded to their relative potency as mitogens. c-Fos appearance and MAP kinase translocation poorly correlated in individual cells. Many cells accumulated c-Fos without any detectable p42/p44 MAP kinase translocation. The heterogeneity of proliferative responses to EGF could be due to the lack of c-Fos or MAP kinase responsiveness of many cells. (ii) TPA induced c-Fos accumulation and MAP kinase translocation within the whole cell population, which did not explain the heterogeneity of the growth response to this factor and showed that these events are not sufficient to elicit DNA synthesis, (iii) TSH and forskolin induced a weak c-Fos accumulation in only a minority of cells but, as previously shown, no p42/p44 MAP kinase phosphorylation and translocation. An important c-Fos expression was thus dispensable for the strong DNA synthesis stimulation exerted by cAMP-dependent mitogens. (iv) Forskolin potentiated the EGF effect on c-Fos expression but not on p42/p44 MAP kinase phosphorylation and translocation. This reflected the fact that EGF induced c-Fos accumulation in 90% of cells in the presence of forskolin but in 30-50% of cells in its absence. This kind of potentiation, which specifically implies an increase in the fraction of responding cells, is termed "generalization" in the present study.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

The distribution and phosphorylation of the microtubule-associated protein MAP 1B in growth cones.

Primary cultures of dissociated embryonic day 18 rat cerebral cortices were labelled by immunofluorescence with antibodies directed either against phosphorylated and non-phosphorylated MAP 1B (antibody 81) or against phosphorylated MAP 1B (antibody 150). Both antibodies stain cortical neurons, including their neurites and growth cones, in early (18 h) cultures, whereas only antibody 81 stained glial cells. By 4 days in culture, phosphorylated MAP 1B is largely restricted to axonal processes and growth cones, where it is often distributed in a gradient that is highest distally. In axonal processes and growth cones after 18 h and 4 days in culture, the phosphorylated form of MAP 1B is present both in a soluble form and bound to microtubules. Growth cones isolated from postnatal day 5 rat forebrain were labelled in vitro with 32P-orthophosphate and detergent soluble and insoluble (cytoskeleton) fractions prepared. SDS-PAGE analysis revealed several major phosphoproteins in isolated growth cone cytoskeletons, including MAP 1B. Phosphorylated MAP 1B was also present in the detergent soluble fraction of growth cones. Immunoblotting and immunoprecipitation with MAP 1B antibodies confirmed the identification of MAP 1B and that the protein is phosphorylated in growth cones. These data show that MAP 1B, in particular the phosphorylated isoform, is present in growth cones and suggest that phosphorylation of MAP 1B may play an important role in neurite elongation.

Animals↗
PubMed1998

Making sense of the multiple MAP-2 transcripts and their role in the neuron.

Microtubule-associated protein-2 (MAP-2) is a family of heat-stable, phosphoproteins expressed predominantly in the cell body and dendrites of neurons. Three major MAP-2 isoforms, (MAP-2a, MAP-2b, MAP-2c) are differentially expressed during the development of the nervous system and have an important role in microtubule dynamics. Several MAP-2 cDNA clones that correspond to the major MAP-2 transcripts and additional, novel MAP-2 transcripts expressed in the CNS and PNS have been characterized. The transcripts result from the alternative splicing of a single MAP-2 gene consisting of 20 exons. Studies are now being directed toward understanding the role of the multiple MAP-2 forms that contain novel exons in the nervous system. The expression, localization, and possible functions of the newly identified spliced forms are the focus of this review.

Animals↗
PubMed1998

[High frequency current ablation of ectopic atrial tachycardia. Different mapping strategies for localization of right- and left-sided origin].

UNLABELLED: Ectopic atrial tachycardia (EAT) is a rare form of supraventricular tachycardia and often drug-resistant. Radiofrequency catheter (RFC) ablation offers an alternative therapy suggesting a high efficacy rate. Localization of the EAT origin is proposed to be efficacious by various mapping strategies. We analyzed the efficacy of different mapping strategies for localization of right and left sided EAT foci. METHODS AND PATIENTS: In a cohort of 48 patients (25 female: age 35 +/- 18 years) RFC ablation of 40 right and 12 left sided EAT foci was performed. Mapping of the right atrium was achieved with 2 ablation catheters using the "encircling" technique (Figure 1). We looked for an early bipolar local electrogram in relation to the onset of the P-wave and a QS-complex in the unipolar electrogram. The bipolar local electrogram was retrospectively analyzed for a fragmented morphology and duration of more than 50 ms (Figure 3). In case of mechanical block of the EAT during mapping P-wave pace mapping over the mapping catheter was performed (Figure 4). RESULTS: RFC ablation succeeded in 44 patients with 46 EAT foci (Figure 5). Left sided EAT origin was in 40% in the region of the pulmonary veins. Two left sided foci were abladed within the coronary sinus. An anteroseptal location in vicinity to the bundle of His was found in 4 cases (Figure 6). There were no differences between left and right sided origin regrading session duration (304 +/- 131 vs 241 +/- 101 min) and fluoroscopic time (39 +/- 29 vs 31 +/- 19 min). The activation time related to the onset of the P-wave was at successful ablation site for left sided origin significantly earlier compared to a right sided origin (45 +/- 22 vs 30 +/- 18 ms). Fragmenation of the bipolar local electrogram was found before successful RFC application in 86% in the left and in 65% in the right atrium. The unipolar electrogram showed in 87% of all cases a QS-complex before the successful RFC pulse. In 16% a beat to beat change of the unipolar electrogram could be found at successful ablation site (Figure 7). Both criteria had a low specify and sensitivity. Mechanical block could be induced during mapping in 10 patients (20%). In these cases RFC application at a site with a perfect match of P-wave pace mapping succeeded in 8 patients. In 2 patients the same EAT occurred within the following 24 hours. During a follow-up of 4 to 58 months there were additionally recurrence of EAT in 3 patients (3 to 6 months after ablation). No influence of the AV nodal conduction was observed after ablation of anteroseptal EAT foci. Other acute or chronic complications were not observed. CONCLUSIONS: 1. RFC ablation of right and left sided EAT foci is a safe and efficacious treatment. There were no differences regarding session duration and fluoroscopic time between right and left sided foci. 2. Activation mapping showed an earlier activation time for left sided origin compared to right sided. 3. Mechanical block could be induced in 20% of cases. P-wave pace mapping might offer a strategy to localize the focus during mechanical block.

Adolescent↗
PubMed2002

A reference map of Cucumis melo based on two recombinant inbred line populations.

A composite genetic melon map was generated based on two recombinant inbred line (RI) populations. By analyzing the segregation of 346 AFLPs, 113 IMAs and phenotypic characters on a RI population of 163 individuals derived from the cross Védrantais x PI 161375, a first map was constructed. About 20% of the molecular markers were skewed, and the residual heterozygosity was estimated at 4.43% which was not significantly different from the theoretical value of 4.2%. The genome distribution of molecular markers among the 12 linkage groups was not different from a random distribution with the exception of linkage group XII which was found significantly less populated. The genome distributions of IMAs and AFLPs were complementary. AFLPs were found mainly in the middle of each linkage group and sometimes clustered, whereas IMAs were found mainly at the end. A total of 318 molecular markers, mainly AFLP and IMA markers, were mapped on 63 RIs of the second population, Védrantais x PI 414723. Comparison of the maps enables one to conclude that AFLPs and IMAs of like molecular size, amplified with the same primer combination, correspond to the same genetic locus. Both maps were joined through 116 common markers comprising 106 comigrating AFLPs/IMAs, plus five SSRs and five phenotypic markers. The integrated melon map contained 668 loci issuing from the segregation of 1,093 molecular markers in the two RI populations. The composite map spanned 1,654 cM on 12 linkage groups which is the haploid number of chromosomes in melon. Thirty two known-function probes, i.e. known-function genes (9) and morphological traits (23), were included in this map. In addition, the composite map was anchored to previously published maps through SSRs, RFLPs and phenotypic characters.

Journal Article↗
PubMed2002

Genetic mapping of 66 new microsatellite (SSR) loci in bread wheat.

In hexaploid bread wheat ( Triticum aestivum L. em. Thell), ten members of the IWMMN ( International Wheat Microsatellites Mapping Network) collaborated in extending the microsatellite (SSR = simple sequence repeat) genetic map. Among a much larger number of microsatellite primer pairs developed as a part of the WMC ( Wheat Microsatellite Consortium), 58 out of 176 primer pairs tested were found to be polymorphic between the parents of the ITMI ( International Triticeae Mapping Initiative) mapping population W7984 x Opata 85 (ITMI pop). This population was used earlier for the construction of RFLP ( Restriction Fragment Length Polymorphism) maps in bread wheat (ITMI map). Using the ITMI pop and a framework map (having 266 anchor markers) prepared for this purpose, a total of 66 microsatellite loci were mapped, which were distributed on 20 of the 21 chromosomes (no marker on chromosome 6D). These 66 mapped microsatellite (SSR) loci add to the existing 384 microsatellite loci earlier mapped in bread wheat.

Journal Article↗