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Biomedical subjects

G Horvath

Publications and source records attributed to G Horvath.

At least 37 records · Page 2Linked to original sources
PubMed2000

Simultaneous occurrence of atrial fibrillation and atrial flutter.

INTRODUCTION: Early reports suggested that some patients with "atrial fibrillation/flutter" might have atrial fibrillation in one atrium and atrial flutter in the other. However, more recent conceptions of atrial fibrillation/flutter postulate that the pattern is due to a relatively organized (type I) form of atrial fibrillation. We report the occurrence and ECG manifestations of simultaneous atrial fibrillation and flutter in patients undergoing attempted catheter ablation of atrial flutter. METHODS AND RESULTS: In patients undergoing radiofrequency ablation for atrial flutter, an attempt was made to entrain atrial flutter by pacing in the right atrium. The arrhythmias observed occurred following attempts at entrainment, or spontaneously in one case. Twelve transient episodes of simultaneous atrial fibrillation and flutter were observed in five patients. The atrial fibrillation was localized to all or a portion of one atrium, during which the other atrium maintained atrial flutter. In each case, the surface 12-lead ECG reflected the right atrial activation pattern. No patients had interatrial or intra-atrial conduction block during sinus rhythm, suggesting functional intra-atrial block as a mechanism for simultaneous atrial fibrillation/flutter. CONCLUSION: In certain patients, the occurrence of transient, simultaneous atrial fibrillation and flutter is possible. In contrast to prior studies in which it was suggested that left atrial or septal activation determines P wave morphology, the results of the present study show that P wave morphology is determined by right atrial activation. Functional interatrial block appears to be a likely mechanism for this phenomenon.

Animals↗
PubMed2000

[Animal protection during transport in Hungary].

To assess animal welfare during transport in Hungary, a questionnaire study was carried out in 1998. The questionnaire consisted of 39 questions addressing some general characteristics as well as specific ones regarding means of transport, fulfillment of the animals' needs on board and others. Three-hundred and ninety-one questionnaires were analysed representing about 0.1% of all yearly transports in Hungary. The most significant problems encountered were with conditions of transport that are more relevant for longer transports, especially those exceeding eight hours. Such are, inter alia, weather protection, ventilation, means to tie or separate animals and the provision of food and water. Even though there are several different types of vehicle available for transporting animals in Hungary, vehicles that are not appropriate for the species, distance or other conditions of the transport are sometimes used. Our results apply to the preparatory phase before the introduction of new, EU conform legislation on the protection of animals during transport. They enable more specific investigations or corrective measures to be undertaken by the competent authority responsible for the enforcement of such regulations in Hungary.

Animal Husbandry↗
PubMed1999

Antinociceptive effects of intrathecal endomorphin-1 and -2 in rats.

Endomorphin-1 and endomorphin-2 were recently postulated to be endogenous mu-opioid receptor agonists. We have investigated the antinociceptive and antihyperalgesic effects of intrathecally administered endomorphins in cumulative doses (0.1-100 microg) on acute and inflammatory pain sensations in awake rats. In the tail-flick test, both peptides caused a dose-dependent short-lasting antinociception, except at the highest dose, which caused motor impairment also. The dose-response curves revealed the development of acute tolerance (tachyphylaxis) to endomorphin. Similarly in the carrageenan-injected paw, the endomorphins (10 microg) exerted transient antinociceptive effects. These are the first data to demonstrate decreased responsivity in models of both acute and inflammatory pain after intrathecal administration of endomorphin-1 and -2 in awake rats.

Analgesics, Opioid↗
PubMed1999

A new gypsogenin saponin from arenaria filicaulis

The structure elucidation of a new saponin from Arenaria filicaulis (Boiss.), Caryophyllaceae, Snatzkein F (1), containing gypsogenin with a tetrasaccharide moiety was accomplished by use of 1D and 2D NMR methods.

Journal Article↗
PubMed1999

Advanced epithelial ovarian cancer: 1998 consensus statements.

BACKGROUND: During an international workshop held in September 1998, a group of specialists in the field of ovarian cancer reached consensus on a number of issues with implications for standard practice and for research of advanced epithelial ovarian cancer. METHODS: Five groups of experts considered several issues which included: biologic factors, prognostic factors, surgery, initial chemotherapy, second-line treatment, the use of CA 125, investigational drugs, intra-peritoneal treatment and high-dose chemotherapy. The group attempted to arrive at answers to questions such as: Are there prognostic factors, which help to identify patients who will not do well with current therapy? What is the current best therapy for advanced ovarian carcinoma? What directions should research take in advanced ovarian cancer? These issues were discussed in a plenary meeting. RESULTS: One of the major conclusions drawn by the consensus committee was that in previously untreated advanced ovarian cancer, cisplatin plus paclitaxel has been shown to be superior to previous standard therapy with cisplatin plus cyclophosphamide (level I evidence). However, for many patients, carboplatin plus paclitaxel is a reasonable alternative because of toxicity and convenience considerations. Most participants felt that the benefits in terms of toxicity for the paclitaxel-carboplatin are such that its widespread adoption at this stage is justified. Until mature survival data are available a minority of investigators would recommend continued use of cisplatin plus paclitaxel, specifically for those patients with advanced disease with the best prognostic characteristics. For future clinical research in this area, new end points for randomised clinical trials, together with a new Trials Network, are proposed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Biokinetics of the monoclonal antibodies MOv 18, OV 185 and OV 197 labelled with 125I according to the m-MeATE method or the Iodogen method in nude mice with ovarian cancer xenografts.

The biodistribution of the radiolabelled monoclonal antibodies MOv18, OV185 and OV197 in nude mice with subcutaneous tumours of the human ovarian cancer cell line OVCAR3 was investigated. The early uptake of MOv18 (1-24 h) and the uptake in relation to tumour size were also studied. The antibodies were labelled with 125I according to the Iodogen method or the m-MeATE method, the latter also being suitable for labelling with 211Astatine. The tumour/blood ratio and the localization index for Mov 18 72 h after antibody injection were 2.21 +/- 0.25 and 4.62 +/- 1.27, respectively. This is significantly higher than for the other two specific antibodies. The early tumour uptake of MOv18 was low with a tumour/blood ratio of 0.23 +/- 0.04 after 6 h, and the uptake was higher in small tumours. The two labelling methods were found to be equivalent. We conclude that MOv18 labelled according the m-MeATE method should be suitable for further therapeutic studies with 211Astatine in nude mice.

Animals↗
PubMed1999

Captopril-induced toxic epidermal necrolysis and agranulocytosis successfully treated with granulocyte colony-stimulating factor.

Captopril-induced bone marrow suppression is rare, except in certain high-risk patient populations. Severe exfoliative rashes have also been associated with captopril, but a combined presentation of toxic epidermal necrolysis and agranulocytosis has not been previously described. We report an unusual case of captopril-induced toxic epidermal necrolysis with agranulocytosis in a patient with no known risk factors. The bone marrow suppression was successfully treated using granulocyte colony-stimulating factor (G-CSF), and the white blood cell (WBC) count recovered within 3 days after starting therapy. This case underscores the early experience with captopril, which showed a strong correlation between high doses used to treat hypertension and bone marrow suppression.

Agranulocytosis↗
PubMed1999

Inappropriate implantable cardioverter-defibrillator therapy due to the detection of premature ventricular complexes.

Inappropriate shocks delivered by implantable cardioverter-defibrillators may occur in 15%-40% of patients treated with these devices. This article describes a rare cause for inappropriate shocks. Two patients received inappropriate shocks due to the presence of premature ventricular complexes during attempted reconfirmation of ventricular fibrillation. Knowledge of device algorithms for detection and reconfirmation of ventricular fibrillation, designed to have a high degree of sensitivity and therefore lower specificity, allows for reprogramming to avoid further inappropriate shocks.

Aged↗
PubMed1999

Characteristics of ischemic and peri-ischemic regions during ventricular fibrillation in the canine heart.

INTRODUCTION: Although premature beats originating in areas of ischemia have been shown to be important in initiating ventricular fibrillation (VF), the participation of the ischemic zone in maintenance of VF has not been investigated. METHODS AND RESULTS: Ten normal dogs underwent induction of two separate episodes of VF, before and 10 minutes after left anterior descending coronary artery ligation. Ischemic VF was allowed to occur spontaneously or was induced by burst pacing after 10 minutes of ischemia. Unipolar epicardial electrograms were recorded using an 8 x 14 plaque electrode array (interelectrode distance 2.5 mm) placed over the anterior wall. Activation during VF was characterized by VF cycle length (CL) and wavefront organization based on linking analysis of epicardial activation directions at adjacent sites. Individual plaque sites were separated into regions based on electrogram morphology during ischemia: R1 = no ischemia; R2 = mild-to-moderate ischemia (minor ST elevation and QRS widening); and R3 = severe ischemia (marked ST elevation and QRS widening). Percent conduction block was calculated based on the percent of cycles during which sites were not activated during VF. There were no significant differences noted in mean CL or mean percent conduction block in the peri-ischemic region R1 compared to the same region under nonischemic (control) conditions. During ischemia, the mean CL was noted to increase in R2 from 111+/-14 msec (control) to 128+/-29 msec (ischemia) and in R3 from 113+/-14 msec (control) to 150+/-42 msec (ischemia) (P < 0.05). The percentage conduction block in R2 increased from 6%+/-11% (control) to 14%+/-16% (ischemia) and in R3 from 4%+/-6% (control) to 44%+/-21% (ischemia) (P < 0.05). Linking analysis revealed no significant changes in VF organization at distances of 2.5 mm in regions R1 and R2 under both control and ischemic conditions. Premature beats initiating fibrillation originated at the border between the normal and mildly ischemic zones. CONCLUSIONS: (1) Some VF characteristics are altered in ischemic regions including a longer VFCL and greater percentage of functional block. (2) VF characteristics are unchanged in immediately adjacent nonischemic myocardium. (3) Although the ischemic zone may be involved in the initiation of VF and has unique activation characteristics during VF, it does not affect VF characteristics in the adjacent nonischemic zone, suggesting that it may not play a major role in VF maintenance.

Animals↗
PubMed1999

Differential effects of parasympathetic blockade and parasympathetic withdrawal on heart rate variability.

INTRODUCTION: Low heart rate variability (HRV) has been shown to have important prognostic significance in multiple settings. Although this is believed to reflect reduced parasympathetic tone, the physiology of reduced parasympathetic tone has not been elucidated. METHODS AND RESULTS: To evaluate whether parasympathetic withdrawal and partial parasympathetic blockade result in similar changes in HRV, 27 normal volunteers underwent complete beta-adrenergic blockade and then were given (1) graded doses of nitroprusside to achieve baroreflex-mediated parasympathetic withdrawal and (2) low-dose atropine (0.01 mg/kg) to achieve partial parasympathetic blockade. Five-minute ECG recordings were obtained for HRV analysis. In 19 subjects, paired 5-minute recordings from each condition were available with mean RR intervals that differed by < 50 msec (low-dose atropine: 869 +/- 96 msec and nitroprusside 875 +/- 99 msec). The root mean square of the successive RR interval differences was lower following low-dose atropine than following parasympathetic withdrawal with nitroprusside (16 +/- 11 msec vs 22 +/- 15 msec; P < 0.02). During parasympathetic withdrawal, the low-frequency (LF) power was 0.917 +/- 0.602 bpm2 and the high-frequency (HF) power was 0.501 +/- 0.521 bpm2. During partial parasympathetic blockade, the LF and HF powers were significantly lower (0.443 +/- 0.474 bpm2, P < 0.005; and 0.198 +/- 0.207 bpm2, P < 0.02). CONCLUSION: These data confirm that HRV reflects the character of parasympathetic modulation of the heart rate rather than parasympathetic tone per se. Furthermore, this study identifies two distinct physiologic explanations for the finding of low HRV, namely, diminished vagal discharge and resistance of cardiac muscarinic receptors to vagal discharge. Further delineation of the relationships between parasympathetic tone and HRV will allow for better understanding of the pathophysiologic derangements associated with low HRV.

Adult↗
PubMed1999

Effect of isoflurane on defibrillation threshold in biphasic active-can defibrillation systems.

In two patients receiving implantable cardioverter-defibrillators (ICD) for spontaneous and inducible ventricular tachyarrhythmias, the use of isoflurane appeared to significantly lower defibrillation thresholds (DFT) at implantation. In the first, at initial implantation and subsequent revision using isoflurane, adequate DFTs were verified by multiple tests. Post-implantation testing using midazolam and fentanyl revealed significantly higher DFTs, necessitating a third operation without isoflurane to obtain an adequate and subsequently verifiable DFT. During the second case, discontinuation of isoflurane intraoperatively resulted in a DFT rise within 25 minutes. In patients receiving general anesthesia for ICD implantation, this possible DFT effect of isoflurane should be recognized.

Anesthetics, Intravenous↗
PubMed1998

Effects of hormone replacement therapy on QT interval.

We evaluated the electrocardiograms of 208 postmenopausal women (ages 40 to > or = 70 years) without heart disease, medications that could alter the QT interval, use of vaginal estrogens, unknown hormone replacement therapy, or electrocardiographic abnormalities both with (n = 76) and without (n = 132) hormone replacement therapy, and found no significant effects of hormone replacement therapy status on heart rate, QT interval, or the corrected QT interval. Thus, estrogen and/or progesterone effect does not explain the gender differences in myocardial repolarization.

Adult↗
PubMed1998

Long-term results from a phase II study of single agent paclitaxel (Taxol) in previously platinum treated patients with advanced ovarian cancer: the Nordic experience.

BACKGROUND: Owing to the wide spread perception of a possible benefit from paclitaxel in the second-line situation the Nordic Gynecologic Oncology Group (NGOG) conducted two prospective phase II studies of paclitaxel single agent treatment (175 mg/m2, three-hour i.v. infusion with standard pre-medication every third week) in patients with relapsing or progressing epithelial ovarian cancer following platinum. PATIENTS AND METHODS: Between 1992-1994 138 patients in total were enrolled of whom 136 received paclitaxel and were included in the toxicity and survival analysis, while 112 were evaluable for response. RESULTS: The overall response rate (CR + PR) was 28% with 16 patients achieving a CR (14%). The estimated median (range) time to progression was 4.1 (0.7-60.7) months. The projected four-year overall survival was 7%, with a median (range) of 9.6 (0.3-60.7) months. A multivariate logistic regression analysis showed that platinum resistance, and WHO performance status at baseline, independently correlated with survival at all three time points (median survival time 9.6, 18, and 24 months). Patients with platinum sensitive tumors and WHO performance status 0 had a median survival of 25.6 months compared to 7.0 months for the rest of the patients (P < or = 0.0001). No serious toxicity was registered. CONCLUSION: Paclitaxel could safely be administered in an outpatient setting using this schedule. Patients with platinum sensitive tumors and a good performance status were most likely to survive. However, these patients are also most likely to respond to re-treatment with a platinum compound. With reference to the reasonably good tumor control and limited toxicity observed in this study, we conclude that paclitaxel single agent therapy is a viable option in the salvage situation, which in some patients can give long-lasting responses. However, although responses can be induced in a significant number of patients, the survival figures remain poor.

Adult↗
PubMed1998

Detection of ventricular fibrillation by transvenous defibrillating leads: integrated versus dedicated bipolar sensing.

INTRODUCTION: Dedicated bipolar sensing has been suggested to be safer than integrated bipolar sensing due to an increased incidence of failure to redetect ventricular fibrillation after an unsuccessful shock with leads that use integrated bipolar sensing. We compared sensing characteristics during ventricular fibrillation of simultaneously recorded dedicated and integrated bipolar electrograms. METHODS AND RESULTS: Thirty patients undergoing transvenous defibrillator implantation with a Transvene lead were studied. Simultaneous recordings were made from the dedicated bipole and the integrated bipole from the distal tip to the coil (interelectrode distance 18.3 mm). The mean detection time and number of undetected beats for the initial episode of ventricular fibrillation were 2804 +/- 569 msec and 0.9 +/- 0.8 using the dedicated recordings and 2938 +/- 546 msec and 1.4 +/- 1.1 (P = 0.026) using the integrated recordings. The mean redetection times and number of undetected beats following a failed first shock (n = 13) were 2468 +/- 225 msec and 0.8 +/- 1.1 for the dedicated recordings and 3042 +/- 498 msec (P < 0.0003) and 4.2 +/- 4.2 (P < 0.005) for the integrated recordings. Frequency analysis of the ventricular fibrillation electrograms demonstrated that the signal energy in the dedicated electrograms was significantly greater than the energy in the integrated electrograms (P < 0.0001). There was a significant negative relationship between detection times and the ventricular fibrillation signal energy. There was no independent effect of recording type (dedicated versus integrated). CONCLUSION: There are only minor differences in detection/redetection of ventricular fibrillation between dedicated and integrated (with tip to coil spacing of 18.3 mm) recording configurations. Detection times during ventricular fibrillation are related to the signal variance or energy recorded. Differences in the sensing performance of the two recording configurations can be explained by the differences in signal energy between the dedicated and integrated recordings that occur during ventricular fibrillation.

Defibrillators, Implantable↗
PubMed1998

Long-term chemotherapy of ovarian cancer: two case reports.

The treatment period of patients with advanced ovarian cancer is generally limited to about six months and maintenance chemotherapy is seldom used. The present report describes two women given chemotherapy continuously for several years with apparently good efficacy and acceptable toxicity.

Aged↗
PubMed1997

Utility of predischarge and one-month transvenous implantable defibrillator tests.

We evaluated the utility of performing predischarge implantable cardioverter-defibrillator (ICD) testing and ICD testing at 1 month in detecting ICD-related problems, identifying 4 patients with an unacceptable increase in defibrillation threshold. Given that ICD testing is noninvasive and has minimal (if any) associated risk, we recommend that predischarge and 1-month follow-up ICD testing should be performed after implantation.

Aged↗
PubMed1997

Chromatin structure of the lymphocyte Fc epsilon receptor gene (CD23): identification of an upstream transcriptional enhancer.

The low-affinity receptor for IgE of lymphocytes, Fc epsilonRII or CD23, is likely to play pivotal roles in normal B cell differentiation, EBV induced B cell immortalization and regulation of the IgE response to allergens and to parasitic infection. We have studied the expression of CD23 mRNA in several cell contexts. In EBV-infected Burkitt lymphoma cells, we have confirmed that high levels of expression are determined largely at the level of gene transcription by performing nuclear run-on transcription analyses and stability determinations of CD23 mRNA in actinomycin D chase experiments. In an effort to define the complexity of the potential modes of activation of CD23 in various cell contexts, we have studied the chromatin structure of the gene as determined by the pattern and distribution of DNasel hypersensitive sites in CD23. We have found that, unlike the results obtained in many analogous systems, there is no distinct pattern of hypersensitive sites that uniquely correlates with high levels of CD23 transcription in various B lineage cell lines. Instead, we found a complex pattern that suggests that CD23 expression is regulated by trans-acting regulatory factors whose activity is dependent upon the stage of cellular differentiation as well as the cell lineage. By determining whether the DNA encompassing these hypersensitive sites contains transcriptional enhancer activity, we discovered a novel enhancer that functions in an EBV-dependent fashion and encompasses a 384-bp segment that lies 3.7 kb upstream from the transcription start site.

Base Sequence↗