Non-invasive electrophysiologic study with amagnetic transesophageal pacing during unshielded multichannel magnetocardiographic mapping.

UNLABELLED: Multichannel magnetocardiographic (MCG) mapping is a non-invasive method, which can provide reproducible three-dimensional (3D) localization of accessory pathways (AP) and ventricular arrhythmias, before ablation procedures. More recently MCG imaging of intra-atrial reentry circuits has also been reported. So far, reported cases of MCG localization and imaging of arrhythmias were investigated during spontaneous rhythm only, although more relevant information can be obtained during dynamic electrophysiologic study (EPS). For cardiac pacing one could use an amagnetic intracardiac catheter; but this, however, would add invasivity to a non-invasive method. The aim of this study was to validate a novel approach for dynamic non-invasive EPS based on MCG in combination with amagnetic transesophageal pacing (TEP). METHOD: A tetrapolar 7 French amagnetic catheter was developed, which provides effective TEP (with an average stimulation threshold of 10-15 mA) and simultaneous recording of two esophageal atrial electrograms. MCG data were acquired at rest, with a 36-channel MCG system (sensitivity of 20 fT/Hz(1/2)), for 90 to 300 seconds (sampling rate of 1 KHz; bandwidth of DC Hz to 100 Hz), as a function of the type of pacing procedure. 10 patients were investigated, during both continuous and programmed TEP. RESULTS AND CONCLUSIONS: MCG during TEP was feasible and reproducible. It provided: 1) more accurate localization of AP during pacing-induced maximal preexcitation; 2) inducibility of supraventricular AR and imaging of atrial reentry circuits, not spontaneously present; 3) stabilization of the heart rate to improve the accuracy of quantitative estimate of ventricular repolarization parameters.

Magnetocardiographic study of ventricular repolarization in hypertensive patients with and without left ventricular hypertrophy.

UNLABELLED: Previous studies in magnetically shielded rooms have shown that magnetocardiographic (MCG) mapping can be useful to detect early signs of left ventricular hypertrophy (LVH). The aim of this study was to evaluate ventricular repolarization parameters in patients with essential hypertension, associated or not with LVH, by means of unshielded multichannel MCG mapping. METHODS: 31 patients with pharmacologically treated essential hypertension (average BP systolic: 147.8+/-11.2, diastolic: 92.2+/-4.9) since 6.5+/-5.6 years, 13 without and 18 with evidence of LVH (4 by ECG, 11 by echocardiography, and 3 at both), were studied with a 36-channel MCG system (sensitivity of 20 fT/square root of Hz1/2) and with 12-lead ECG, in an unshielded hospital setting. To assess ventricular repolarization, HR-corrected, QTend, JTpeak, JTend, Tpeak-end intervals and QT dispersion (QTd) were measured from both MCG and ECG waveforms. The magnetic field gradient orientation (alpha angle) during the ST interval and at the Tpeak was also computed. 20 normal age-matched volunteers were used for comparison. RESULTS: As compared to normal volunteers, MCG JTend, QTend, Tpeak-end and QTd were significantly longer in hypertensive patients. The difference was not significant, if only patients with essential hypertension but no LVH were considered. The magnetic field alpha angle during the ST was significantly abnormal in patients with essential hypertension (p < 0.01). CONCLUSIONS: In patients with essential hypertension, MCG detects alterations of ventricular repolarization, not evidenced by 12-lead ECG.

Magnetocardiographic differences of ventricular repolarization parameters between Wistar rats and guinea pigs.

UNLABELLED: The morphology and range of duration of the action potential (AP) in normal Wistar rat's (WR) myocyte markedly differ from those of guinea pigs (GP), whose plateau (phase 2) duration is longer. Thus a clear-cut T wave can be easy defined in GP but not in WR. Aim of this study was to differentiate magnetocardiographic (MCG) ventricular repolarization (VR) parameters of healthy adult WR and GP. METHODS: 10 female animals (5 Guinea pigs and 5 Wistar rats) were studied with a 36-channel MCG system (sensitivity of 20 fT/square root of Hz1/2) and with one ECG lead, in an unshielded hospital room. To assess VR, HR-corrected, JTpeak, JTend, Tpeak-end and QTend, intervals were measured from both MCG waveforms. Timing was improved by MCG maps analysis. Magnetic field orientation (MFO), its dynamics (MFD) and stability (JTS) during the JT interval, were also automatically computed from MCG maps. RESULTS: All repolarization intervals were significantly shorter in WR than in GP, except the Tpeak-end, which was longer. MFO and MFD also differed. CONCLUSIONS: MCG estimate of VR parameters, in adult WR and GP, is precise enough to evidence breed-related differences, consistent with physiological heterogeneity of duration during phases 2 and 3 of the AP, and with an higher degree of transmural dispersion of repolarization in WR.

Effects of filtering on computer-aided analysis for detection of chronic ischemic heart disease with unshielded rest magnetocardiographic mapping.

UNLABELLED: Recent studies have reported better sensitivity of magnetocardiographic (MCG) mapping, as compared to ECG, in detecting ventricular repolarization (VR) abnormalities due to myocardial ischemia in patients (pts) with Ischemic Heart Disease (IHD). For quick data reduction, automatic analysis of MCG mapping is mostly used. The aim of our study was to evaluate if filtering modality could alter automatic analysis of MCG. METHOD: 39 subjects were studied: 20 normals and 19 IHD pts, with angiography-documented >70% coronary stenosis, positive stress/SPECT and ischemic 12-lead ECG in 12/19 (63%). Rest MCG was recorded with a 36-channel system (at 1 kHz; bandwidth DC-100 Hz). To assess VR, Hänninen's STalpha angle and three magnetic field dynamics parameters, [i.e. +/- poles: angle (A), distance (D) and ratio (R)] during the T-wave interval, were computed from the same MCG maps: 1) after digital 20 Hz low-pass filtering (LPF) and 2) after digital 50 Hz adaptive filtering (AF). The baseline was unchanged. Three quantitative MCG scores of the T-wave (EXT, ML, Q) were automatically calculated (with 20 Hz LPF only). RESULTS: Whereas the filtering modality didn't affect the predictivity of the STalpha angle, the predictive values of A, D, and R were different and partially contradicting. Automatic MCG scores had a predictive values ranging between 73% and 92%. CONCLUSIONS: The diagnostic power of unshielded MCG for detection of chronic IHD, with T-wave parameters (A, D and R) might be affected by LPF. The STalpha angle is not affected by LPF. Automatic EXT, ML and Q scores have better predictivity than ECG.

Clinical multichannel MCG in unshielded hospital environment.

UNLABELLED: From November 5th, 2001 to May 19th, 2004, 545 patients (177 with arrhythmias, 67 with WPW syndrome, 60 with Ischemic Heart Disease (IHD), 129 with different kinds of cardiomyopathy, 106 normals, 6 FMCG) have been consecutively investigated at the Catholic University of Rome, with unshielded Multichannel Magnetocardiographic Mapping (MMCG): 20 with the 9-channel system only and 525 with the 36-channel system (207 of them with both systems). 107 patients were investigated also after physical stress, carried out with a standard bicycle ergometer. In all patients MMCG was recorded at least three times, to check for reproducibility and/or for clinical follow-up, for a total of more than 1600 recordings. METHOD: MMCG was performed, with both the 9-channel and the 36-channel systems, at 1 kHz in the bandwidth DC-100 Hz. In the last 200 pts, 12-lead ECG was simultaneously recorded with amagnetic electrodes. On each patient file, post-processing and signal analysis for the quantitative assessment of ventricular repolarization and for 3D localization and electroanatomical imaging of cardiac arrhythmias, were carried out independently with two different approaches and software programs developed by CMI and by Neuromag (Finland). RESULTS: The results with the two methods have been compared. For 3D electroanatomical integration of MMCG localization results, 3D cardiac models have been used, constructed from patient MRI and/or from orthogonal fluoroscopic images taken at the moment of MCG recording. CONCLUSIONS: Qualitative reproducibility of MMCG was satisfactory. However the estimate of quantitative parameters has shown a certain degree of variability, which deserves further evaluation.

Clear-cell and papillary carcinoma of the kidney: an analysis of chromosome 3, 7, and 17 abnormalities by microsatellite amplification, cytogenetics, and fluorescence in situ hybridization.

Clear-cell and papillary renal cell carcinomas (RCCs) have specific genetic changes that allow them to be classified on the basis of histopathology and on the basis of cytogenetic and molecular genetic findings. Clear-cell carcinomas are characterized by a deletion of gene sequences on the short arm of chromosome 3 (3p). Papillary RCCs do not have 3p deletions but have an increase in chromosomal number that usually includes trisomies of chromosomes 7 and 17. This study was undertaken to determine whether PCR-amplified DNA microsatellites can be used to detect numerical abnormalities of chromosomes 7 and 17 and whether the numerical abnormalities and 3p deletions that are detected by microsatellite analysis can be correlated with histopathologic tumor types. A series of histologically unambiguous RCCs consisting of three papillary and ten clear-cell RCCs were studied by cytogenetics and by fluorescence in situ hybridization (FISH) with chromosome 7 and 17 centromeric probes. Microsatellites on the long and short arms of chromosomes 3, 7, and 17 were amplified in paired normal tissue and tumor samples, and the reaction products were analyzed for differences between the normal and the tumor allele ratios. Clear-cell carcinomas showed loss of heterozygosity (LOH) of 3p but not 3q alleles in eight of ten cases. LOH of 3p and 3q was seen in one case of papillary RCC that cytogenetically had two normal chromosomes 3. This indicated a nondisjunction duplication that could be confused with monosomy 3 if only microsatellite studies were performed. Differences in microsatellite allele ratios between normal tissue and tumor correlated with the presence of trisomy 7 that was identified in clear-cell and papillary RCCs by cytogenetics and by FISH. Microsatellite analysis did not detect numerical chromosome 17 abnormalities in the papillary RCCs but did show an abnormality in one clear-cell carcinoma that was markedly aneusomic for chromosomes 7 and 17 by FISH. In this collection of cases, microsatellite amplification genetically distinguished only clear-cell RCCs showing 3p but not 3q LOH as a separate class of tumors. The method detected abnormalities in chromosome number that were found in both clear-cell and papillary RCCs.

Deletion 1p in a low-grade chondrosarcoma in a patient with Ollier disease.

Ollier disease is an uncommon, nonhereditary developmental disorder affecting enchondral ossification. Cytogenetic analysis of low-grade chondrosarcoma in a patient with Ollier disease (multiple enchondromatosis) revealed an interstitial deletion, del(1)(p11p31.2), as the only chromosome abnormality. This is the first cytogenetic study of a chondrosarcoma in a patient with Ollier disease. Such patients are at risk of developing chondrosarcoma and, because del(1p) is frequent in chondrosarcoma, it is suggested that this cytogenetic finding is associated with early chondrosarcomatous transformation.

Cloning of a breakpoint cluster region on chromosome 14 in uterine leiomyoma.

A recurrent reciprocal chromosomal translocation, t(12;14)(q15;q24) is frequently observed in uterine leiomyoma. Chromosome 12 breakpoints have been shown to occur in a region of approximately 150 kb that contains the gene for a high mobility group protein (HMGI-C). The breakpoint region on chromosome 14 has not been precisely defined. We have generated a contig of overlapping yeast artificial chromosome (YAC) clones approximately 3 Mb in size. Fluorescence in situ hybridization (FISH) analysis showed that this contig spanned the t(12;14) breakpoints in three uterine leiomyomas and that the breakpoints in these tumors occurred within a 1 Mb region. A 30 kb cosmid spanning one of the breakpoints was isolated to set the stage for identifying regions on chromosome 14 that may cause this region to be a preferential site for chromosomal translocation.

Molecular analysis of chromosome 7q21.3 in uterine leiomyoma: analysis using markers with linkage to insulin resistance.

Recent sibling-pair linkage analyses have indicated possible linkage of noninsulin dependent diabetes mellitus (NIDDM) with a number of markers on the long arm of chromosome 7. A coincidental and recent discovery is that specific genetic anomalies identified on chromosome 7 in uterine leiomyoma tumor cells in many cases correspond, cytogenetically, to the same region where genetic linkage to insulin resistance has been identified. In the present study, 15 closely spaced microsatellite markers were used to finely map deletion breakpoints and to test for allelic loss of 7q markers in 12 uterine leiomyoma tumor samples with cytogenetically defined deletions. Of the 9 informative tumor samples, three exhibited breakpoints in the same region where genetic linkage to insulin resistance has been identified (between PON and UT901). Because breakpoints in neoplasias often occur within or adjacent to expressed sequences, these breakpoints may provide a molecular tool to aid in the identification of candidate genes for insulin resistance.

Leptomeningeal metastasis from a paraspinal rhabdomyosarcoma with a der(13)t(1;13)(q23;q32) in a 14-month-old boy.

Cytogenetic analysis performed on a 14-month-old boy with a primary retroperitoneal/paraspinal alveolar rhabdomyosarcoma showed the presence of a der(13)t(1;13)(q23;q32) resulting in partial trisomy of the 1q23-->qter region and loss of the 13q32-->qter region. The present case is discussed with reference to a similar case reported in the literature.

Hepatic undifferentiated (embryonal) sarcoma arising in a mesenchymal hamartoma.

We report the case of a hepatic undifferentiated (embryonal) sarcoma (UES) arising within a mesenchymal hamartoma (MH) in a 15-year-old girl. Mapping of the tumor demonstrated a typical MH transforming gradually into a UES composed of anaplastic stromal cells. When evaluated by flow cytometry, the MH was diploid and the UES showed a prominent aneuploid peak. Karyotypic analysis of the UES showed structural alterations of chromosome 19, which have been implicated as a potential genetic marker of MH. The histogenesis of MH and UES is still debated, and reports of a relationship between them, although suggested on the basis of histomorphologic similarities, have never been convincing. The histologic, flow cytometric, and cytogenetic evidence reported herein suggests a link between these two hepatic tumors of the pediatric population.

Fine mapping of the human renal oncocytoma-associated translocation (5;11)(q35;q13) breakpoint.

Recent cytogenetic analysis of a series of human renal oncocytomas revealed the presence of a recurring chromosomal translocation (5;11)(q35;q13) as sole anomaly in a subset of the tumors. The molecular characterization of this translocation was initiated using two primary t(5;11)-positive renal oncocytomas and a panel of somatic cell hybrids derived from one of these tumors, in conjunction with fluorescence in situ hybridization (FISH) and Southern blot analysis. The breakpoint in chromosome band 11q13 could be located within a genomic interval of at maximum 400 Kb immediately centromeric to the BCL1 locus.

Two discrete regions of deletion at 7q in uterine leiomyomas.

This study further defines the region of consistent deletion of chromosome 7 in uterine leiomyomas. We have examined 74 leiomyomas for allelic loss of markers spanning the 7q22 region defined by markers D7S518 and D7S471. Forty tumors with cytogenetically defined 7q deletions, twenty-nine tumors without cytogenetically visible 7q deletions, and five tumors with no cytogenetic information were examined for allelic loss of D7S518, D7S666, D7S515, D7S658, D7S496, D7S692, and D7S471. Loss of heterozygosity for one or more of these loci was observed in twenty-eight leiomyomas with cytogenetically defined 7q deletions and in three leiomyomas with a normal karyotype. Allelic loss of D7S666 was common and was observed in all twenty-three informative tumors with 7q deletions and in two tumors with normal karyotypes. This study indicates the presence of a tumor suppressor gene in close proximity to the D7S666 locus. Eight tumors followed an unusual pattern of allelic loss. These tumors showed retention of heterozygosity for at least one locus flanked by deleted loci. These results suggest the possibility that two discrete regions of deletion at 7q22 are involved in the development of a subset of leiomyomas.

Misexpression of disrupted HMGI architectural factors activates alternative pathways of tumorigenesis.

Cancer arises from aberrations in the genetic mechanisms that control growth and differentiation. HMGI-C and HMGI(Y) are members of the HMGI family of architectural factors expressed in embryonic or undifferentiated cells and highly associated with transformation. Translocations of 12q13-15 in lipomas (fat cell tumors) disrupt HMGI-C and fuse its DNA-binding domains to novel transcriptional regulatory domains. This study shows that in a rare, karyotypically distinct group of human lipomas, rearrangements of 6p21-23 produce internal deletions within HMGI(Y). Activation of the rearranged alleles leads to expression of aberrant HMGI(Y) transcripts in differentiated adipocytes. A molecular analysis of these transcripts demonstrates that fusion of HMGI DNA-binding domains to putative transcriptional regulatory domains was not necessary for lipoma formation. However, such fusions may facilitate tumor development because activation of the wild-type HMGI allele, normally required for tumorigenesis, is bypassed in lipomas which express chimeric HMGI proteins. We hypothesize that HMGI misexpression in a differentiated cell is a pivotal event in benign tumorigenesis, and the molecular pathway of tumor development depends upon the precise nature of HMGI disruption.

Renal cell carcinoma of end-stage renal disease: a histopathologic and molecular genetic study.

Renal cell carcinomas (RCC) are responsible for the deaths of 3% to 4% of patients with ESRD. The clear cell carcinoma of the kidney, which comprises 80% of sporadic RCC within the general population, shows a deletion of gene sequences in the short arm of chromosome 3 (3p) in as many as 100% of cases. The von Hippel-Lindau tumor suppressor gene at 3p25-26 is found to be mutated in the nondeleted allele in 57% of these sporadic clear cell carcinomas. This study was undertaken to determine the histopathologic types of RCC occurring in ESRD patients in the United States and to investigate the frequency with which 3p genetic changes can be found in these ESRD tumors. Seventeen end-stage kidneys containing RCC were collected from 15 ESRD patients at ten US medical centers. The tumors were classified by Thoenes' histopathologic typing. DNA extracted from paraffin blocks of tumor and nontumorous tissue was analyzed by single-stranded conformational polymorphism analysis for von Hippel-Lindau mutations and by microsatellite amplification for deletion of 3p gene sequences. Twenty-one RCC were identified in the 18 kidneys. The 21 RCC were classified histopathologically as follows: clear cell, compact, three cases; chromophilic, tubulopapillary, 15 cases; chromophilic, compact, three cases. Among the three clear cell carcinomas, one showed 3p genetic loss. None of the chromophilic RCC showed a 3p deletion and none of 19 tumors studied by single-stranded conformational polymorphism analysis disclosed von Hippel-Lindau mutations. In contrast to the general population, clear cell RCC with 3p abnormalities represent only a small proportion of the renal carcinomas in this collection of ESRD tumors. The findings indicate that the genetic changes underlying the development of most ESRD tumors are different from those occurring in sporadic clear cell RCC and do not characteristically involve the inactivation of a 3p tumor suppressor gene.

Renal cell carcinoma in an end-stage kidney of a patient with a functional transplant: cytogenetic and molecular genetic findings.

Renal cell carcinomas (RCCs) occur at an increased rate and at a younger age in patients with end-stage renal disease (ESRD) than in the general population. A papillary RCC from a patient with ESRD treated by hemodialysis and then by renal transplantation was karyotyped and showed a 55,XY,+2,+4,+7,+10,+12,+16,+17,+17,+20 mainline. No loss of gene sequences in the short arm of chromosome 3 was identified by chromosomal or molecular genetic analysis. Together with one prior report of a cytogenetic study of a RCC in an end-stage kidney, the findings indicate that papillary RCCs that arise in ESRD patients have genetic changes that are similar to those found in sporadic tumors. The increased frequency of tumors and the younger age of the patients may be due to an increased rate at which abnormal mitoses occur in diseased renal tissues.

FISH studies on the Y chromosome in male urinary cells.

To ascertain the meaning of the loss of the Y (-Y) in bladder cancer, we addressed the incidence of -Y in urinary cells in relation to age in 35 men without bladder cancer. Aside from the bone marrow and blood, -Y has not been examined critically in other tissues and organs in a large series of men. The present study clearly demonstrated that -Y in the group studied was an infrequent finding and not related to age.