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Biomedical subjects

D Pfeiffer

Publications and source records attributed to D Pfeiffer.

At least 91 records · Page 5Linked to original sources
PubMed1997

mRNA expression of ligands of the epidermal-growth-factor-receptor in the uterus.

Six different ligands of the epidermal-growth-factor receptor (EGFR) have been identified in the past. In some cervical squamous-cell carcinomas, an increased amount of proteins binding to the EGFR has been reported. In order to identify the mRNA of EGFR ligands (EGFRL), which might be overexpressed in cervical and endometrial cancers, we performed semi-quantitative reverse-transcription/polymerase chain reactions (RT-PCR) for all 6 EGFRL in RNA extracts of normal and malignant tissue samples of the human uterus. PCR products from RNA extracts of 83 patients were quantitated relative to the housekeeping gene and internal standard pyruvate dehydrogenase by analyzing the PCR kinetics of product synthesis. In extracts of normal cervix, the level of mRNA expression of the EGFRL was significantly higher than in endometrium. No significant difference was detected between normal cervix and cervical carcinomas. However, both in cervical and in endometrial cancers, mRNA expression was non-parametrically distributed and in some cervical cancers overexpression of transforming growth factor alpha (TGF-alpha), amphiregulin or EGF was observed. In endometrial cancers, mRNA levels of all EGFRL were higher than in normal endometrium. This increase was significant (p < 0.005) for TGF-alpha and amphiregulin. Thus, TGF-alpha mRNA is overexpressed in approximately 10% of cervical cancers and in the majority of endometrial cancers. Since TGF-alpha anti-sense therapy might represent a future strategy in such cancers, we also determined the absolute level of TGF-alpha mRNA expression by quantitative PCR using a cloned standard.

Cloning, Molecular↗
PubMed1997

[Septic myocardial aneurysm in mitral valve endocarditis. Clinical and pathological-anatomical findings].

HISTORY AND CLINICAL FINDINGS: A 68-year-old woman was hospitalized because of fever and tiredness for 3 months. Her general condition was clearly impaired. She had a mild fever of 38.5 degrees C and on auscultation a 3/6 systolic murmur, maximal parasternally in the 3rd intercostal space, transmitted to the apex. There were distant râles over both lungs, the neck veins were distended and there was ankle oedema. INVESTIGATIONS: C-reactive protein was raised to 17.3 mg/dl (normal up to 0.9 mg/dl), WBC count 19,300/microliter. beta-haemolysing streptococcus (S. agalactiae) was grown in the blood culture. The ECG showed sinus tachycardia (rate of 98/min) and transthoracic echocardiography demonstrated a small pericardial, enlarged ventricles, marked mitral regurgitation and a large vegetation on the posterior mitral leaflet, as well as a 3 x 4 cm mass in the posterior wall of the ventricle, originating from the posterior mitral valve ring and communicating with the vegetation on the mitral valve. The posterior mitral leaflet was perforated. TREATMENT AND COURSE: As endocarditis of the mitral valve with a complicated course was suspected-abscess of the posterior mitral valve ring and septic myocardial aneurysm with associated pericarditis and haemodynamically insignificant effusion-she was transferred to the intensive care unit where she died suddenly of circulatory arrest only 30 min after transfer. Autopsy confirmed the echocardiographic findings. CONCLUSION: Paravalvular abscess in the course of mitral valve endocarditis is rare, but should be looked for at transthoracic echocardiography so that any necessary surgical intervention can be undertaken early.

Aged↗
PubMed1997

Commercial biosensors for medical application.

Biosensors today are represented on the market worldwide by an increasing number of enzyme electrodes working in various areas of medical diagnostics, and by a few opto-immunosensor-based analytical systems suited for protein research in pharmaceutical chemistry. Enzyme electrodes for metabolites and enzyme activities have been commercially available for about 20 years. Such sensors are successfully applied in laboratory autoanalyzers, point-of-care-systems, patient self-monitoring disposable probes, intensive care analyzers, and for on-line monitoring of diabetics.

Biosensing Techniques↗
PubMed1997

[10 years radiofrequency ablation of accessory conduction pathways].

Catheter ablation of the preexcitation syndrome is a curative treatment. Accessory pathways between structures of the specific conduction system or working myocardium are morphologic prerequisites for orthodromic or antidromic reentrant tachycardia of various frequency, duration, and rate. Detection of mechanisms of tachyarrhythmias and understanding the role of accessory pathways in tachycardia, mapping of accessory connections, function of nodal conduction system, and additional accessory pathways are necessary for successful catheter ablation. Anomalies of the tricuspid valve and coronary sinus and concomitant disease of the heart should be investigated prior to catheter ablation using echocardiography and contrast injection. Different variations of the preexcitation syndrome and the results of catheter ablation in 300 patients are demonstrated. Catheter ablation is indicated in refractory tachyarrhythmias on the basis of accessory pathways. The treatment is performed in a catheterization laboratory by two highly experienced cardiologists in the field of electrophysiology after training in 100 procedures. The investigators need experience in interventional treatment of coronary artery disease, in transseptal puncture, and in the management of complications (coronary and valvular problems, thromboemboly, and pericardial drainage). Catheterization needs careful protection of radiation. An ablation is possible at an atrial or ventricular insertion site of the accessory pathway or in between. Ablation is done during sinus rhythm, atrial stimulation, antidromic reentry, or atrial fibrillation or during ventricular pacing and orthodromic tachycardia. The procedure should end with bidirectional block of the accessory pathway in 90-95% of the patients. Complications occur in 2-4% of procedures. Recovery of accessory conduction is observed in 8%. Catheter ablation of the accessory pathway is the treatment of first choice in symptomatic patients with the pre-excitation syndrome. The procedure has limited risks and a high success rate.

Cardiac Pacing, Artificial↗
PubMed1997

[Radiofrequency ablation in ventricular extrasystole of the right ventricular outflow tract].

The series of five patients with symptomatic isolated right ventricular outflow tract ectopy and no structural heart disease which were successfully treated with radiofrequency ablation of the ectopic focus are reported in order to discuss radio-frequency ablation as an alternative treatment in patients with right ventricular outflow tract ectopy without ventricular tachycardia.

Cardiac Complexes, Premature↗
PubMed1997

Amperometric lactate oxidase catheter for real-time lactate monitoring based on thin film technology.

An amperometric lactate oxidase catheter has been developed for in vivo application to real-time lactate monitoring. The electrochemical behaviour of the 1 x 3 mm Pt-Ag/AgCl thin film electrode is not significantly influenced by lactate oxidase-polyurethane covering. Gamma-irradiation (25 kGy) is suitable for the sterilization procedure. The final lactate catheter is characterized by a linear concentration range between 0.5 and 20 mmol/l lactate with a sensitivity around 2 nA mmol-1 l-1 lactate. The accuracy is demonstrated by the measurement of control sera. Both physiological and pathological materials correlate well with the declared values. The dry stored lactate catheter needs about 10 min for hydration and is characterized by response times t98% of less than 2 min. Ex vivo whole blood measurements using the lactate catheter (y) give a correlation with the BIOSEN Med L (x) of y = (1.010x + 0.513) mmol/l (r = 0.9748). Lactate values obtained by continuous catheter operation ex vivo correlate well with those obtained by BIOSEN Med L. First subcutaneous implantation (dog) underlines the characteristics obtained ex vivo: after 30 min hydration the lactate catheter follows the lactate concentration measured ex vivo with samples from the leg vein by BIOSEN Med L.

Animals↗
PubMed1997

Ultrasensitive bienzyme sensor for adrenaline.

A biosensor consisting of an analyte-recycling two-enzyme system using laccase (Coriolus hirsutus) and PQQ-dependent glucose dehydrogenase in combination with the electrochemical detection of oxygen depletion at a platinum electrode was used for adrenaline determination in the nano- and subnanomolar concentration range. Measurements were performed in a flow cell providing excellent baseline stability and fast recovery of the sensor. Improved design of the polymer matrix resulted in a lower detection limit of 200 pmol/l for adrenaline. The sensor has successfully been applied to the analysis of adrenaline in effluate of isolated rabbit hearts.

Animals↗
PubMed1997

Dose and rate-dependent effects of adenosine on atrial action potential duration in humans.

Adenosine provokes atrial fibrillation (AF) in some patients with paroxysmal supraventricular tachycardia (PSVT). Which patients are more susceptible to develop atrial fibrillation after the administration of adenosine to terminate PSVT is unknown. We prospectively measured atrial action potential duration (APD) at incremental doses of 3, 6, and 12 mg of adenosine at paced cycle lengths (CLs) of 600, 500, and 400 ms in 25 patients. Bolus injection of adenosine decreased APD at 90% repolarization in a dose- and rate-dependent manner. During paced CLs of 600, 500, and 400 ms, decreases of 8%, 13%, and 19% (p < 0.05), respectively, were found after bolus administration of 3 mg of adenosine. After 6 mg of adenosine, the APD shortened by 12%, 19%, (p < 0.05), and 27% (p < 0.01), respectively. After 12 mg of adenosine, the APD shortened by 15%, 27% (p < 0.05), and 38% (p < 0.01), respectively. Transient AF occurred in 4 of 25 (16%) patients, all during paced CLs of 400 ms, and after adenosine 6 mg in one patient and 12 mg in three patients. Adenosine shortens atrial action potential duration in a dose- and rate-dependent manner. Whether patients with faster rates during PSVT and those given higher doses of adenosine are more prone to develop atrial fibrillation remains to be determined.

Action Potentials↗
PubMed1997

Radiofrequency catheter ablation of atrial flutter that elicits inappropriate implantable cardioverter defibrillator discharge.

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow-up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.

Atrial Flutter↗
PubMed1997

Novel instrumentation for real-time monitoring using miniaturized flow systems with integrated biosensors.

A prototype miniaturized Total Chemical Analysis System (muTAS) has been developed and applied to on-line monitoring of glucose and lactate in the core blood of anaesthetized dogs. The system consists of a highly efficient microdialysis sampling interface sited in a small-scale extracorporeal shunt circuit ('MiniShunt'), a silicon machined microflow manifold and integrated biosensor array for glucose and lactate detection with associated computer software for analytical process control. During in-vivo testing the device allowed real-time on-screen monitoring of glucose and lactate with system response times of less than 5 min, made possible by the small dead volume of the microflow system. On-line glucose and lactate measurements were made in the basal state as well as during intravenous infusion of glucose or lactate. The prototype muTAS is currently suitable for trend monitoring but refinements are necessary before application of the system for determination of individual lactate values.

Animals↗
PubMed1997

The evaluation of fee for service and managed care from the viewpoint of people with disabilities in the USA.

In the literature on managed health care there is little presented from the viewpoint of people with disabilities, but this study looks at what is found. Using a sample of 258 persons with disabilities in Massachusetts obtained through a mail survey, no statistically significant differences between the two groups (fee for service or managed care) on a series of relevant variables was found. An evaluation of their health insurance and their primary care physician was asked for and several regression models of the relevant variables related to these two evaluations were tested. It seems that accessibility of the primary care physicians's office and the physician's level of understanding of the person's disability are related in a statistically significant way to their rating of their health insurance. Also it appears that the ease of obtaining an appointment and the physician's level of understanding of the person's disability are related in a statistically significant way to the evaluation of their primary care physician. The major policy implication of these findings is that managed care may not be the disaster which many foresee it to be.

Attitude to Health↗
PubMed1996

Epicardial neodymium. YAG laser photocoagulation of ventricular tachycardia without ventriculotomy in patients after myocardial infarction.

BACKGROUND: Surgical ablation of ventricular tachycardia (VT) after myocardial infarction has been reported by different endocardial approaches. The ventriculotomy may increase mortality of the procedure. METHODS AND RESULTS: We report on nine patients who suffered from recurrent VT in the late post-myocardial infarction period. Significant stenoses were detected in all patients. The mean left ventricular ejection fraction was 43.1 +/- 8.3%. Left ventricular scar (n = 9) was seen. The mean NYHA class was 2.2 +/- 0.4. Sustained VT (mean cycle length, 293 +/- 52 ms) occurred spontaneously (n = 9) and could be induced reproducibly. Catheter mapping detected a prematurity of -42 +/- 13 ms in six patients. Clinical VT was inducible during surgery in seven patients. Middiastolic potentials were detected from the epicardial surface (n = 3), and premature potentials were found (n = 8 with prematurity of -108 +/- 46 ms). Application of neodymium/yttrium/argon/ garnet (Nd:YAG) laser energy to early epicardial activation terminated the arrhythmia (n = 7). Ventriculotomy was not performed. Seven patients have been free of VT for a mean follow-up period of 17 +/- 11 months; one patient relapsed and was treated with an implantable cardioverter-defibrillator, as was a second patient with inducible VT after surgery. CONCLUSIONS: Surgical Nd:YAG laser photocoagulation of VT on the epicardial surface of the heart in post-myocardial infarction patients without ventriculotomy is safe and has a high success rate. At the present time, this method is recommended in patients with sustained and tolerated VT who need bypass surgery. This is the first report on epicardial laser ablation of VT in post-myocardial infarction VT.

Adult↗
PubMed1996

Nonpharmacologic strategies for treating atrial fibrillation.

Nonpharmacologic tools to treat atrial fibrillation (AF) are direct current cardioversion, radiofrequency (RF) current catheter ablation, antiarrhythmic surgery, pacing, and atrial defibrillation. In patients with sustained AF, when no cause can be found for AF or when the associated disease is mild, an attempt should be made to restore sinus rhythm. Electrical cardioversion by synchronized direct current shock can be attempted when drugs have failed and is the first choice in acutely ill patients. Virtually all patients should be anticoagulated. Temporary pacing should be available in patients with evidence of previous bradycardia. Although efficacy may be improved in patients pretreated with antiarrhythmic drugs, there is a considerable risk of adverse events. In AF and sinus node dysfunction, both pacing and antiarrhythmic drugs may be necessary. Pacing should be atrial or dual chamber, since ventricular pacing provokes AF. Failure to control the ventricular rate in AF can be treated by RF: atrioventricular (AV) node ablation, ablation of accessory pathways in preexcitation syndrome with AF, modulation of AV node, or ablation of AF. Antiarrhythmic surgery is a major procedure and may be the therapy of last resort in AF: the so-called corridor procedure isolates the fibrillating atria from a strip of tissue connecting the sinus and AV nodes. The maze procedure attempts to abolish AF by channeling the atrial activation between a series of incisions. In patients with chronic AF, internal cardioversion should be attempted if conventional transthoracic electrical cardioversion is ineffective. Several studies demonstrated the feasibility and efficacy of internal atrial defibrillation in selected patients with recent onset, as well as with chronic, AF. An implantable atrial defibrillator--as a stand-alone device or as part of a whole heart cardioverter--might be an option in the future. Nonpharmacologic tools play only a minor role in the management of paroxysmal and chronic AF. If symptoms persist despite pharmacologic therapy and other causes of persisting symptoms are excluded, consideration should be given to cardiac pacing, RF catheter treatment, or surgery. in some cases nonpharmacologic therapy of the AV node must be followed by implantation of a permanent pacemaker (due to complete AV block) and anticoagulation (due to persistence of underlying AF.

Adolescent↗
PubMed1996

Direct angiography of the coronary sinus: impact on left posteroseptal accessory pathway ablation.

The purpose of this study was to determine the incidence and types of venous branches and anomalies in posteroseptal accessory pathways (APs) and whether these findings are indicative for successful ablation sites. Some posteroseptal APs may be located epicardially, or may be associated with venous anomalies or related to the middle cardiac vein. These APs account for many of the failures encountered during endocardial ablation. Direct coronary sinus (CS) angiography was performed in 43 consecutive patients with left posteroseptal APs (n = 23) and in 20 patients with AV nodal reentrant tachycardia prior to catheter ablation. In 14 (61%) of 23 APs, a venous branch or an anomaly of the CS was found in the posteroseptal region (6 with middle cardiac vein, 2 with other ventricular venous branches, and 6 had a diverticulum). Eleven (48%) of 23 APs were successfully abolished from within that demonstrated venous system, with a median of four radiofrequency impulses. In the remaining 12 (52%) patients, ablation was attempted from the endocardial site of the mitral annulus. Repeat angiography after energy delivery revealed no major complications in any patient. One (5%) patient with AV nodal reentrant tachycardia had evidence of a CS anomaly (P < 0.01). Various types of venous branches and anomalies are associated with the majority of patients with left posteroseptal APs. The APs are directly related to these complex findings, and AP conduction can easily be eliminated from within the venous branches. CS angiography is suggested prior to catheter ablation of left posteroseptal APs to facilitate the ablation procedure.

Adult↗
PubMed1996

["Contra laparoscopy" position in treatment of testicular varicocele].

Laparoscopic varicocelectomy does not offer any significant advantage in comparison to sclerotherapy or open surgical procedures. Invasiveness (transperitoneal approach, intraoperative complications, general anesthesia, duration of operation, possible ligation of the spermatic artery) is not less, but the technical expenditure and costs are higher than those in competing procedures. Laparoscopic treatment is not the procedure of first choice and even in recurrent varicocele it should only be performed if prior treatment by-repeated antegrade sclerotherapy is not successful and distal reflux has been ruled out. Therefore, the laparoscopic approach is of only minor value in the treatment of varicocele testis.

Contraindications↗