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PubMed1988

Aspiration of bovine oocytes during transvaginal ultrasound scanning of the ovaries.

A technique for the repeated collection of bovine oocytes using transvaginal ultrasound guided aspiration is described. Cows were used during their normal estrous cycle and after stimulation of the ovaries with pregnant mare serum gonadotrophin (PMSG). The sedation of the animals and the puncturing of follicles appears not to have traumatized the animals and plasma progesterone measurements suggested that the cyclicity was not interrupted. A total of 36 transvaginal aspiration procedures were performed, during which 54 oocytes were recovered from 197 follicles. These experiments indicate that the repeated aspiration of bovine oocytes during transvaginal ultrasound scanning is possible. However, more research is needed to establish optimal methods for improving the recovery rate of oocytes before this method can be used as an alternative route for the supply of oocytes for in vitro maturation and in vitro fertilization.

Journal Article↗
PubMed1998

IS195, an insertion sequence-like element associated with protease genes in Porphyromonas gingivalis.

Porphyromonas gingivalis is recognized as an important etiologic agent in adult and early-onset periodontal disease. Proteases produced by this organism contribute to its virulence in mice. Protease-encoding genes have been shown to contain multiple copies of repeated nucleotide sequences. These conserved sequences have also been found in hemagglutinin genes. In the process of studying the genetic loci containing the conserved repeated sequences, we have characterized a prtP gene homolog from P. gingivalis W83 encoding a cysteine protease with Lys-X specificity. However, this prtP gene was interrupted by an insertion sequence-like element which we designated IS195. Furthermore, IS195 and another element, IS1126, were present downstream of prtP gene homologs (kgp) found in P. gingivalis H66 and 381. IS195, a 1,068-bp insertion sequence-like element, contained 11-bp inverted repeats at its termini and was bordered by 9-bp direct repeats presumed to be a transposition-mediated target site duplication. Its central region contained one large open reading frame encoding a predicted 300-amino-acid protein which appeared to be a transposase. We isolated two naturally occurring variants of P. gingivalis W83, one carrying IS195 within the coding region of the prtP gene and another containing an intact prtP gene. Biochemical characterization revealed a lack of trypsin-like Lys-X specific proteolytic activity in the P. gingivalis W83 variant carrying the disrupted prtP gene. Studies using a mouse model revealed a reduction of virulence resulting from insertion of IS195 into the coding region of the prtP gene. An allelic-exchange mutant defective in the prtP gene also was constructed and tested in vivo. It displayed intermediate virulence compared to that of the wild-type and prtP::IS195 mutant strains. We conclude that the Lys-X cysteine protease contributes to virulence in soft tissue infections.

Amino Acid Sequence↗
PubMed2001

Flemish population data and sequence structure of the hypervariable tetranucleotide repeat locus D12S1090.

The allele frequency and sequence structure of the STR locus D12S1090 were investigated in 598 Flemish individuals. The locus shows a complex organisation with repetitions of GATA interrupted by TA and other tetra- and pentanucleotide blocks. No deviation from Hardy-Weinberg equilibrium was observed. The extensive polymorphism makes it a powerful tool for identity as well as paternity testing and even permits differentiation of closely related populations, such as Flemish and Germans. D12S1090 seems to be one of the most informative STRs, however, as seen in other highly variable STRs, the observed mutation frequency of 5.1 x 10(-3), is relatively high. of STR loci is typing highly polymorphic STRs such as ACTBP2 [3]. We thus investigated the tetranucleotide (GATA) repeat locus D12S1090 (GDB accession number GDB:376560, also known as GATA5A09) in a population sample from Flanders, the Dutch speaking part of Belgium. Although this STR is considered to be highly polymorphic [4], compared with other STRs, it has only scarcely been studied.

Alleles↗
PubMed2001

Planned interruptions of anti-HIV treatment.

Highly active antiretroviral therapies (HAART) lower morbidity and mortality of HIV infection, but are unable to eradicate HIV and may cause side-effects. Planned interruptions of HAART are studied for three reasons: (1) to stimulate the anti-HIV immune response after viraemia has been suppressed by treatment; (2) to increase time off drug, to improve quality of life and diminish side effects and costs; and (3), among individuals whose virus has become resistant to treatment, to induce reversion of resistance to wild-type and therefore to improve the chances of success of subsequent salvage therapy. Regarding immune stimulation, the most promising results come from rare patients who started HAART during primary HIV infection. Up to 60% controlled viraemia below 5,000 copies/mL for up to 1 year without HAART. Among the majority of patients who start HAART later, during chronic HIV infection, preliminary results suggest that after repeated cycles on and off therapy, about 20% remain with a viraemia below 5,000 copies/mL after 12 weeks' treatment interruption. For the 80% who rebound to higher viraemia, additional immune-stimulatory manoeuvres are being considered such as administration of cytokines, or specific immune treatment by anti-HIV vaccines. When treatment is interrupted in patients who fail HAART and who have drug-resistant HIV, the drug-sensitive wild-type replaces the resistant quasispecies in 30-60% of patients. It remains to be seen whether this phenomenon increases the chances of successful salvage therapy. The risks and benefits of treatment interruption still have to be compared in large clinical trials, which are currently in the planning stage.

Antiretroviral Therapy, Highly Active↗
PubMed2005

Genotype/phenotype correlation in a SCA1 family: anticipation without CAG expansion.

We report on a family with spinocerebellar ataxia type 1 (SCA1), in which the age at onset and the severity of the disease do not correlate with the number of CAG repeat units. Although a marked anticipation was observed in the proband, it was not a consequence of an expansion of the CAG tract. None of the expanded alleles contained CAT interruptions. The pathologic expansion in this family was stable during the paternal but not maternal transmission, where it expanded by one trinucleotide and unexpectedly did not lead to anticipation. Our observations suggest that factors other than the length of the CAG repeat play a considerable role in determination of the disease course.

Adult↗
PubMed1996

Discrepant effects of mexiletine on cycle length of ventricular tachycardia and on the effective refractory period in the area of slow conduction.

OBJECTIVE: Monomorphic sustained ventricular tachycardia (VT) can often be entrained and interrupted at a critical paced cycle length. The aim was to evaluate a possible determinant of this phenomenon by observing the action of mexiletine on the critical paced cycle length and other variables. METHODS: Nine consecutive patients with symptomatic VT were studied. After induction of VT, the area of slow conduction was mapped as the earliest site of the activation or the site with mid-diastolic potential during the tachycardia. Rapid pacing was performed at a site distant from the tachycardia circuit to entrain the tachycardia, starting at a cycle length 10-20 ms shorter than the VT cycle length, and repeated after a decrement of the cycle length in steps of 10 ms to obtain the longest paced cycle length that interrupted the tachycardia: the block cycle length. The effective refractory period (ERP) was measured at the pacing site at which the myocardium was presumed to be normal and also in the area of slow conduction. The effects of mexiletine on the cycle length of VT, the block cycle length, and the ERP at two sites were obtained before and after mexiletine administration. The relation between the cycle length of VT and block cycle length and their changes were also analysed. RESULTS: 11 VTs with the same morphology were induced before and after mexiletine administration. The VT cycle length was prolonged by mexiletine from 309 (SD 53) to 361 (47) ms, and it was interrupted at block cycle lengths of 247 (37) and 307 (41) ms, respectively, the changes being 18 (12)% and 23 (8)% (both P < 0.001). All VTs were entrained, and during pacing at the block cycle length there was abrupt loss of fusion and change in the presystolic electrogram, always associated with interruption of VT on cessation of rapid pacing. A good correlation was observed between the VT cycle length and the block cycle length (r = 0.77 to 0.80). The ERP at the pacing site (normal myocardium) and in the area of slow conduction showed no significant change: 241 (21) v 240 (22) ms and 262 (9) v 252 (9) ms, respectively. The block cycle length was longer than the ERP after mexiletine administration: 362 (55) v 252 (9) ms (P < 0.02). CONCLUSIONS: Mexiletine prolonged the cycle length of VT and the VT-interrupting critical cycle length but not the ERP. The prolongation of the VT cycle length and the block cycle length by mexiletine seemed to be unrelated to the action potential duration, but related to depressed intercellular conduction.

Action Potentials↗
PubMed1983

Molecular evolution of the human adult alpha-globin-like gene region: insertion and deletion of Alu family repeats and non-Alu DNA sequences.

Previous heteroduplex studies have revealed extensive sequence homology between the two human adult alpha-globin-like genes (alpha 2 and alpha 1) and their flanking regions. These homologous regions, which are interrupted by two blocks of nonhomology, each span approximately 4 kilobases [Lauer, J., Shen, C.-K. J. & Maniatis, T. (1980) Cell 20, 119-130]. We have determined 3 kilobases of DNA sequences within and flanking the nonhomologous blocks of these two tandem duplication units. A total of three Alu family repeats has been identified. Two of them are approximately 300 base pairs long and define the 3' ends of the first homology blocks. The third Alu family member is a 600-base-pair-long sequence consisting of two monomeric Alu members arranged in a head-to-tail fashion. It is located in the 3' portion of the first block of nonhomology in alpha 2-gene-containing unit. We present direct evidence that this dimeric Alu sequence was inserted at a staggered break. The second nonhomology block is the result of insertion or deletion of a 224-base-pair sequence. From these data and the calculation of sequence divergence, we propose a history for the evolution of the human adult alpha-globin-like gene region. We also suggest that DNA insertion elements may disrupt gene correction processes in the two duplication units containing alpha 2- and alpha 1-globin genes.

Adult↗
PubMed1994

Treatment of cranial dural arteriovenous fistulae by interruption of leptomeningeal venous drainage.

Cranial dural arteriovenous fistulae (AVF's) of the tentorial incisura or the dura of the middle fossa have a much higher incidence of draining via leptomeningeal veins than do AVF's of the transverse-sigmoid sinuses or the cavernous sinus. Such a drainage pattern is associated with an increased incidence of intracranial hemorrhage and progressive focal neurological deficits. Patients with cranial dural AVF's often undergo surgical excision and/or endovascular embolization for elimination of the AVF. Since these lesions are frequently large and involve the skull base or adjacent dural sinuses, extensive surgery is often required. In contrast, spinal dural AVF's with only intradural venous drainage to the medullary venous system are treated successfully by simply interrupting the vein that drains the dural AVF as it enters the subarachnoid space. The authors identified a subgroup of patients with cranial dural AVF's in whom the AVF was drained only by leptomeningeal veins, and sought to establish whether simple interruption of the vein draining the blood from the AVF into the subarachnoid space is effective and lasting treatment in this subgroup of patients, as it is in patients with spinal dural AVF's. Four adult patients with symptomatic cranial dural AVF's (two petrotentorial, one middle fossa floor, and one posterior fossa base) were identified on arteriography as having fistulae that were supplied by the internal and/or external carotid arteries and drained only via leptomeningeal veins (two entered the petrosal vein, one a cerebellar hemispheric vein, and one a mesencephalic vein). All patients underwent interruption of the vein draining the dural AVF as it penetrated the dura to enter the subarachnoid space, and experienced neurological improvement after surgery. Repeat arteriography at 1 to 2 weeks (three patients), 3 months (3 patients), 12 to 15 months (three patients), and 4 years (two patients) revealed no residual AVF and no evidence of abnormal blood flow. Many cranial dural AVF's with leptomeningeal venous drainage (the type with the most aggressive behavior) are drained only by leptomeningeal veins. This subgroup of patients can be identified by selective arteriography and requires only interruption of the draining vein as it enters the subarachnoid space for successful, lasting elimination.

Adult↗
PubMed1992

Spontaneous transformation of rat ovarian surface epithelial cells: association with cytogenetic changes and implications of repeated ovulation in the etiology of ovarian cancer.

BACKGROUND: Ovarian surface epithelial cells undergo several rounds of division to repair the wound created by follicular rupture at the time of ovulation. This cyclical requirement for cell division, when not interrupted by the long anovulatory rest periods that occur during pregnancy and lactation, may contribute to the development of ovarian cancer. PURPOSE AND METHODS: To test this hypothesis, we isolated rat ovarian surface epithelial cells from 10 adult female Fisher rats, initiated two mixed-population and seven clonal cell lines, and repeatedly subcultured these cells in vitro for more than 20 passages. We then tested them for the acquisition of the following four features associated with transformation: 1) the loss of contact inhibition, 2) the capacity for substrate-independent growth, 3) the ability to form tumors when injected subcutaneously and/or intraperitoneally into athymic mice, and 4) cytogenetic abnormalities. RESULTS: Loss of contact inhibition was observed in all nine late-passage cell lines. Six of the nine late-passage, but none of the early-passage, cell lines tested exhibited a capacity for substrate-independent growth that was augmented in a dose-dependent manner by epidermal growth factor. Two late-passage cell lines (clone 2 and mixed-population 2) generated tumors in athymic BALB/c mice within 3 weeks following subcutaneous injection of 5 x 10(6) cells, whereas similar numbers of early-passage cells from the same cell lines failed to generate palpable tumors. Late-passage clone 7 cells were tumorigenic when 5 x 10(7) cells were injected intraperitoneally. Two of the cell lines analyzed exhibited alterations involving losses of part or all of one member of the chromosome 5 pair. Clone 2 possessed an interstitial deletion, del(5)(q21.3q24), consistent with the loss of an uncloned putative tumor suppressor gene at 5q22q23 previously reported to reside near the loci for the interferon alpha, interferon beta, and c-jun genes. Early-passage clone 7 cells exhibited chromosome 5 monosomy, while late-passage cells contained one normal chromosome 5 and a derivative (5q12q). Southern analysis of the three cell lines revealed no consistent loss of loci for the interferon and c-jun genes, although early-passage clone 7 cells had one half the gene copy number for the interferon beta and c-jun genes and both early- and late-passage clone 7 cells lacked DNA sequences hybridizing with the probe for interferon alpha. CONCLUSION: This pattern of passage-dependent spontaneous transformation of rat ovarian surface epithelial cells in vitro supports the hypothesis that repetitious ovulation contributes to the etiology of human ovarian cancer.

Animals↗
PubMed1983

Phase I trial of Indicine-N-Oxide on two dose schedules.

Indicine-N-Oxide is the water soluble N-oxide of the pyrolizidine alkaloid indicine recently evaluated in Phase I trials. Initially in a weekly times four schedule, twenty-nine patients were treated with a dose range of 1.0 to 7.5 g/m2 per week. Fifteen of 40 of the courses of four doses were interrupted by myelosuppression which prohibited completion of the course. Therefore, an intermittent schedule was evaluated utilizing single doses repeated every 3-4 weeks. Twenty-six patients were treated at doses of 5 to 10 g/m2. Myelosuppression is the dose limiting toxicity of both schedules with thrombocytopenia being more severe than leukopenia. Myelosuppression is predictable and reversible on the intermittent schedule. It is more severe in patients with heavy prior treatment. Partial responses were seen in four patients, one with a mucoepidermoid carcinoma of the salivary gland and three with adenocarcinoma of the colon. Phase II studies are planned at a starting dose of 7.5 g/m2 every 3-4 weeks in patients with no prior treatment and 5 g/m2 in patients with prior treatment.

Adult↗
PubMed2003

Occan, a novel transposon in the Fot1 family, is ubiquitously found in several Magnaporthe grisea isolates.

We investigated a DNA fragment and its flanking region deleted in the spontaneous Pi-a virulent mutant of Magnaporthe grisea Ina168. A new transposon-like sequence was identified from a region adjacent to the deleted fragment and was named Occan. Occan contained a 2,259-bp ORF interrupted by one 63-bp intron and had both a TA dinucleotide and 77 bp of perfect inverted repeats at both termini, without direct repeats. These features indicated that Occan is a member of the Fot1 family. RT-PCR analysis confirmed the expression of the putative transposase and the presence of an intron. Southern analysis of pulse-field gel electrophoresis-separated chromosomes indicated that Occan was dispersed in all chromosomes of the rice pathogen, Ina168. Copy numbers of Occan were also preserved in a host-specific manner amongst M. grisea isolates. In particular, rice pathogens contained a large number of the element inserted into their genome. Phylogenetic analysis with other known members of the Fot1 family revealed that Occan was dissimilar to any other known elements and it is thus proposed that Occan be separated to a new subfamily.

Amino Acid Sequence↗
PubMed2003

Inadvertent exposure of pregnant women to ivermectin and albendazole during mass drug administration for lymphatic filariasis.

The current strategy for the interruption of transmission of lymphatic filariasis in areas where the disease is co-endemic with onchocerciasis is repeated annual mass treatment of endemic communities with ivermectin and albendazole. These drugs are not recommended for use in pregnancy. Pregnant women are excluded on the basis of their last menses. This exclusion criterion based on recall carries some inherent errors, leading sometimes to inadvertent exposure of foetuses to these drugs. This study set out to document the extent of inadvertent exposure of pregnant women to albendazole and ivermectin and assess the relative risk of congenital malformations because of inadvertent treatment with these drugs in early pregnancy. The study was conducted in the Ahanta West District of Ghana. Local pregnancy revelation norms were studied, followed by a household survey of women aged 15-45 years to assess drug administration coverage. All infants born within 42 weeks of the mass drug treatment were examined to document any congenital malformations. Mothers who had lost any such infants responded to a verbal autopsy to ascertain the probable cause of death. Health facilities and local Traditional Birth Attendants were also visited to review maternity records. Of 2985 women of childbearing age (15-49 years) who were interviewed, 343 were pregnant during the mass drug administration. The sensitivity of the last menstrual period in detecting pregnancy and thus being excluded from treatment was 0.854 (293 of 343). Some pregnant women 50 of 343 (14.6%) had thus been inadvertently treated. This represents 1.7% of women in fertile age group (15-49 years). Of the six children found with some congenital malformations in these communities, one had been exposed to the drugs in-utero. The relative risk for congenital malformation after exposure was 1.05 (P=1.0). Two of nine reported spontaneous abortions had been exposed to the drugs (P=0.62). We conclude that the local mode of excluding pregnancy in the current programme, while not perfect, is sufficiently effective and reliable for such a public health intervention; and importantly, that there is no evidence of a higher risk of congenital malformation or abortions in those who are inadvertently exposed.

Abnormalities, Drug-Induced↗
PubMed1982

Pemphigoid, pemphigus and Pr antigens in adult human keratinocytes grown on nonviable substrates.

Isolated adult human keratinocytes were grown either on plastic coverslips or a nonviable basement membrane surface containing intact laminin, type IV and V collagens, and heparan sulfate proteoglycan and examined by indirect immunofluorescence for the expression of bullous pemphigoid, pemphigus and Prlh antigens. Initial cell suspensions had a mean of 23% and 30%, respectively, of bullous pemphigoid and Prlh positive staining cells, while those stained with pemphigus serum were usually negative (19 of 22 series). Pemphigus antigen was expressed as intercellular staining between keratinocytes within 24 hr in both cultures on plastic and basement membrane. Likewise, Prlh antigen was expressed within 24 hr as a homogeneous cytoplasmic fluorescence leaving the basement membrane zone unstained. In contrast, pemphigoid antigen was expressed as a linear fluorescent band at the basement membrane zone between days 3 and 4 of culture. Systematic cell counts of bullous pemphigoid antigen positive cells from trypsin disrupted primary cultures made on plastic over time showed a nadir (8%) of positive cells in early cultures after which the percentage rapidly rose to a peak of 58% between days 14 and 21 of culture. In subcultures repeatedly disrupted at short intervals, the percentage of bullous pemphigoid positive cells remained low when compared to those interrupted and passaged over longer intervals. The percentage of bullous pemphigoid antigen bearing cells in culture over time is similar, but not identical, to the percentage of basal cells and is related to the age and known growth kinetics of the cultures system. Bullous pemphigoid, pemphigus and Prlh antigens are synthesized by the epidermal cell whether cultured on basement membrane or plastic.

Antigens↗
PubMed1994

Successful catheter ablation of atrial fibrillation.

INTRODUCTION: Catheter ablation of a case of incessant atrial fibrillation was attempted using linear right atrial lesions created by sequential applications of radiofrequency energy. METHODS AND RESULTS: A 46-year-old patient had incessant episodes of atrial fibrillation. He had previously undergone successful radiofrequency catheter ablation of a common atrial flutter. Antiarrhythmic drugs including amiodarone and various drug combinations were ineffective. A 7-French specially designed 14-polar catheter with interelectrode distance of 3 mm was used to create linear lesions in the right atrium. Each electrode was 4 mm in length and able to transmit radiofrequency energy. Three linear lesions, two longitudinal and one transverse that connected the two longitudinal lesions, were created using 30 radiofrequency applications of 10 to 40 W. The final application interrupted an atrial fibrillation that had been persistent for 55 minutes. No sustained atrial fibrillation was inducible despite repeated pacing maneuvers. There was no complication. In short-term follow-up of 3 months, the patient has been free of arrhythmias without antiarrhythmic medication. CONCLUSION: Successful catheter ablation of human atrial fibrillation is feasible using linear atrial lesions created by radiofrequency energy delivery. Further studies are mandatory to ascertain the efficacy and safety of this procedure, as well as to assess different catheter techniques.

Atrial Fibrillation↗
PubMedDate not supplied

Internal eliminated segments (IESs) of Oxytrichidae.

Internal eliminated segments (IESs) are sequences that interrupt coding and noncoding regions of germline (micronuclear) genes of ciliated protozoa. IESs are flanked by short, unique repeat sequences, which are presumably required for precise IES excision during macronuclear development. Coding and noncoding segments of genes separated by IESs are called macronuclear-destined segments, or MDSs. We have compiled the characteristics of 89 individual IESs in 12 micronuclear genes in the Oxytricha and Stylonychia genera to define the IES phenomenon precisely, a first step in determining the origin, function and significance of IESs. Although all 89 IESs among the 12 different genes are AT-rich, they show no other similarity in sequence, length, position or number. Two main types of IESs are present. IESs that separate scrambled MDSs are significantly shorter and more frequent and have longer flanking repeat sequences than IESs that intervene between nonscrambled MDSs. A comparison of the nonscrambled gene encoding beta-telomere binding protein in three species of hypotrichs shows that even in the same gene IESs are not conserved in sequence, length, position, or number from species to species. A comparison of IESs in the scrambled gene encoding actin I in the three species shows that the evolutionary behavior of IESs in a scrambled gene may be more constrained. However, IESs in the scrambled actin I gene have shifted along the DNA molecule during evolution. In total, the various studies show that IESs are hypermutable in sequence and length. They insert, excise, and shift along DNA molecules more or less randomly during evolution, with no discernible function or consequences.

Animals↗
PubMed1989

Avascular necrosis of lesser metatarsal heads following forefoot surgery.

Three cases of avascular necrosis of the lesser metatarsal heads following forefoot surgery are presented. The variable blood supply of the metatarsal heads is described. Interruption of this delicate circulation at the time of surgery is thought to be a major etiological factor. Repeated trauma following transference of load to the lesser metatarsal heads after operation may also play an important role. Although not previously described this may be a cause of persistent pain following surgery to the forefoot which is easily overlooked.

Adult↗
PubMed1991

Complete primary structure of human collagen alpha 1 (V) chain.

Several cDNA clones, encoding prepropeptide of human collagen alpha 1(V) chain, have been isolated. The prepropeptide (1838 amino acids length) of the alpha 1(V) chain was composed of a putative signal peptide, a large NH2-terminal noncollagenous region, a main collagenous region, and a COOH-terminal noncollagenous region. The signal peptide contained many leucine residues. The NH2-terminal noncollagenous region was much larger than those of the other collagens and had a region homologous to the COOH-terminal domain of laminin A chain, but it did not contain a cysteine-rich region that was maintained in the region of the other collagens. This region also contained probable tyrosine sulfation sites, and short collagenous sequences that were interrupted by three noncollagenous segments. The main collagenous region of the alpha 1(V) chain consisted of 338 repeats of Gly-X-Y-triplet. This region had a high degree (82%) of homology with the amino acids of the collagen alpha 1(XI) chain. The COOH-terminal noncollagenous region resembled that of the alpha 1(XI) chain, too, and 8 residues of cysteine that were important for the formation of the triple helix structure of collagens were observed. These results suggest that the alpha 1(V) chain belongs to the fibrillar collagen relative to the alpha 1(XI) chain, but codon usage of the alpha 1(V) cDNA was clearly different from those of the other fibrillar collagens including the alpha 1(XI), while it was similar to type IV collagen. This result supposes a different evolution of the alpha 1(V) gene from those of the other fibrillar collagens.

Amino Acid Sequence↗
PubMed1990

[Idionodal reciprocal tachycardia irresponsive to pharmacological prophylaxis. Description of a case successfully treated with radio frequency].

The case of a 63-year old female suffering from recurrent paroxysmal supraventricular tachycardia for 30 years is reported. In the past she was treated unsuccessfully with multiple drugs. Electrophysiological study showed dual nodal pathways and the inducibility of a junctional reciprocating tachycardia with RR and V-A intervals respectively 360-410 and 40 msec. Radiofrequency was applied for 30" in the nodal region during induced reciprocating tachycardia. The arrhythmia was interrupted after a few seconds and a 1st degree A-V block persisted for a few minutes. Repeated electrophysiological studies were performed 30 minutes and 20 days after the ablating procedure. They showed a slight increase in AH interval from 55 msec to 90 and 65 msec respectively, as well as the persistence of anterograde dual nodal pathways and the disappearance of retrograde conduction of the A-V node. No reentry arrhythmia could be induced. After six months the patient is asymptomatic and drug free.

Electrocardiography↗