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Biomedical subjects

D Pfeiffer

Publications and source records attributed to D Pfeiffer.

17 recordsLinked to original sources
PubMed1992

Effects of chronic amiodarone therapy on defibrillation threshold.

In a prospective and parallel, randomized study, the long-term stability of epicardial defibrillation threshold was evaluated in 22 patients, using a patch-patch lead configuration at the time of implantation and generator replacement. The concomitant antiarrhythmic drug treatment consisted of either mexiletine (720 mg/day) or amiodarone (400 mg/day) and was administered to patients in a randomized and parallel manner. During a mean follow-up of 24 +/- 6 months, the defibrillation threshold increased significantly from 14.3 +/- 2.8 to 17.9 +/- 5.3 J (p < 0.05) for the entire patient group. The increase in the chronic defibrillation threshold was due to a marked increase in defibrillation energy needs in the subgroup of patients receiving amiodarone. Whereas no significant change in the defibrillation threshold was documented in the subgroup of patients receiving mexiletine, the mean defibrillation threshold increased from 14.1 +/- 3.0 to 20.9 +/- 5.4 J (p < 0.001) in those receiving amiodarone. In all patients with increased defibrillation thresholds, reevaluation showed a reduction in the defibrillation threshold after discontinuation of antiarrhythmic drug therapy. The only variable associated with an increase in the chronic defibrillation threshold was amiodarone treatment. These findings suggest that the defibrillation threshold should be measured at each generator replacement and in case of a change in antiarrhythmic drug treatment. In particular, if amiodarone treatment is initiated, it is recommended that the defibrillation threshold should be reevaluated to ensure an adequate margin of safety.

Amiodarone↗
PubMed1992

[Age-related differences and changes in clinical aspects and follow-up of cervix cancer since 1973].

In an attempt to clarify, whether the malignant potential of cervical cancer is age-dependent and whether this has changed in the last decade, we analysed the data from 1496 patients suffering from cervical cancer. The patients were treated between 1973 and 1988 at the second Universitäts-Frauenklinik, Lindwurmstrasse and at the Frauenklinik Grosshadern, both of the Ludwig-Maximilians-Universität München. After 1973, the total number of patients with cervical cancer decreased, whilst at the same time, the percentage of young patients increased. In the sub-group of surgically treated patients (n = 555), the percentage of patients with lymph node metastases increased after 1973. The increase in lymph node involvement was most pronounced in young patients with small tumours (stage Ib disease, 35 years of age). In this group, the percentage of lymph node involvement rose from 6.3% in 1973 to 38.6% in 1988. Lower stage disease was significantly more frequent in the young patients. Accordingly, the overall mean survival time was longer in the young patients. In the sub-group of surgically treated patients, however, when comparing equal stages, the survival time was shorter in the young patients. In small tumours (confined to the uterine cervix), pelvic lymph node involvement was more frequently seen in the younger patients. Secondary metastases developed more rapidly and significantly more often in the young patients. Our data supply evidence to indicate an enhanced malignancy of cervical cancer in young patients.

Adult↗
PubMed1992

[Wolff-Parkinson-White syndrome: regional endocardial potential and efficacy of high frequency ablation].

The aim of the study was the evaluation of results of radiofrequency (RF) catheter ablation in relation to characteristics of regional endocardial potential morphology. 418 RF current deliveries in 26 patients with anterogradely conducting left-sided accessory pathways (AP) were investigated. A large regional atrial deflection (> 1/4 of ventricular potential) prior to RF discharge is a prerequisite for ablation success using the ventricular approach. A failing or extremely short (< 10 ms) isoelectric interval between atrial and ventricular deflections of the regional potential predicts a block of the AP. A persistent block can be expected if the regional electrogram contains an AP potential and the AP block occurs early (< 5 s) during onset of RF current.

Adult↗
PubMed1992

Treatment of tachyarrhythmias in a patient with the long QT syndrome by autotransplantation of the heart and sinus node-triggered atrial pacing.

The case history of a 37-year-old woman with the long QT syndrome and drug-refractory paroxysmal ventricular tachyarrhythmias is reported. She was resuscitated eight times between 1980 and 1987. The duration of these attacks increased from a few minutes to 8 hours and the interval between them decreased from 2 years to 4 weeks. An autotransplantation was performed of the anatomically and hemodynamically normal heart. She has had normal QT intervals and has been free of tachyarrhythmias since the operation in June 1987. Because of a slow escape low atrial rhythm, she was treated with a dual-chamber pacemaker programmed in the VDD mode with a coupling interval of 15 msec. The pacemaker wires were connected to the nontransplanted atrial cuff ("atrial" wire) and the transplanted atrium ("ventricular" wire). The hemodynamic effect of the resultant sinus node-driven low atrial pacing was restoration of normal values. This is the first report of successful autotransplantation of the heart for ventricular tachyarrhythmias caused by the long QT syndrome.

Adult↗
PubMed1991

Second generation biosensors.

Enzyme-membrane electrodes using glucose oxidase in combination with peroxide detection dominate in the field of laboratory analyzers for diluted samples. Using the same indication principle, extremely fast responding glucose sensors have been fabricated by covering thin metal electrodes with a porous enzyme layer. In the second generation auxiliary enzymes and/or co-reactants are coimmobilized with the analyte converting enzyme in order to improve the analytical quality and to simplify the performance. Following this line oxidizable interferences are suppressed by using a glucose oxidase/peroxidase complex which communicates with the electrode at a low working potential. Furthermore, fluctuations of pH or buffer capacity are ineffective when using a glucose oxidase/peroxidase layer covered fluoride FET in the potentiometric glucose determination. Enzymatic recycling of the analyte and/or accumulation of intermediates increase the sensitivity by several orders of magnitude. Inclusion of NAD bound to PEG in the glucose dehydrogenase layer allows a reagentless glucose measurement.

Biosensing Techniques↗
PubMed1990

[Enzyme liberation after electrical His bundle ablation].

The release of isoenzymes, i.e. aspartate aminotransferase (ASAT), lactic dehydrogenase (LDH), malic dehydrogenase (MDH), and of creatine kinase (CK) after electric His bundle ablation is presented. The enzyme release is increasing with the amount of energy applied during the intervention. Mitochondrial MDH and ASAT were found in six of the seven patients. Therefore, the size of myocardial necrosis by ablation can be estimated by the sequence of the release of the enzymes, and the isoenzymes, respectively.

Adolescent↗
PubMed1990

Amperometric bi-enzyme based biosensor for the detection of lactose--characterization and application.

Based on the glucose oxidase-beta-galactosidase sequence an enzyme probe for the specific determination of lactose has been developed. beta-Galactosidases from different sources have been compared, the sensor containing beta-galactosidase from Curvularia inaequalis has been characterized in respect of optimal pH, enzyme loading, apparent activity and functional stability. The response of the bi-enzyme probe depends linearly on lactose concentration between 0.02 and 3.00 mmol dm-3. The application to different milk and foodstuff samples resulted in good correlations toward enzymatic photometric (y = (0.956x-1.67) mmol dm-3) and infrared detection (y = (1.0772x-0.3909)%). Using a measuring frequency of 100 h-1 the serial imprecision is about 2% for diluted milk, urine, or foodstuff samples.

Animals↗
PubMed1990

[Treatment of tachyarrhythmia in a patient with long QT syndrome by autologous heart transplantation and atrial stimulation controlled by the sinoatrial node].

The authors described an operation performed in a female patient aged 37 years who was first examined in 1980. That year she experienced the first ventricular fibrillation episode. The duration of the Q-T interval was 600 msec. She was examined by a comprehensive protocol which enabled coronary abnormalities to be excluded. The operation was made in July 1987 in the Charite Hospital by Dr. Warnke. The operation involved dissection of the nerve connections nearest the heart by cutting the pulmonary artery, aorta, both atria and subsequently suturing by the scheme used in cardiac grafting. The patient rapidly recovered after the surgery. She had a normal Q-T interval and no recurrences of ventricular tachycardias. Following the surgery she displayed disturbances of intraatrial conduction and pacemaker displacement into the lower segments of the right atrium, so she was implanted a DDD-mode pacemaker.

Adult↗
PubMed1989

Long QT syndrome associated with inflammatory degeneration of the stellate ganglia.

A well-studied case of intermittent long QT syndrome in a 21-year-old female is presented. Electrophysiologic investigation repeated three times revealed changing sinoatrial and atrioventricular dysfunction and nonsustained ventricular tachycardia. The patient died 29 months after first hospitalization in a stage of electromechanical dissociation after runs of torsade de pointes although she had been treated with repeated anti-inflammatory therapy as well as high doses of propranolol. Postmortem examination demonstrated active inflammation of stellate ganglia. Myocardium appeared normal.

Adult↗
PubMed1989

Clinical implications of the epidermal growth factor receptor in the squamous cell carcinoma of the uterine cervix.

The clinical implications of the epidermal growth factor (EGF) and its receptor (EGF-R) were studied in 52 squamous cell carcinomas of the uterine cervix. In comparison to 40 biopsies of the normal cervix EGF-R capacity was significantly increased in the carcinomas, while the affinity was unchanged. The amount of EGF-like substances extracted from the tumors was increased in patients with lymph node metastases, in whom 5-year survival is reduced. Irrespective of tumor stage patients with a very high level of EGF-R (greater than 100 fmole/mg protein) were more likely to have recurrences later or to die from disease: recurrence or death occurred in 5 of 7 patients with high capacity and in 2 of 45 patients with low capacity. Our data suggest that the level of EGF-R is indicative of the biological aggressiveness of cervical carcinomas.

Adult↗
PubMed1989

Human corticotropin-releasing hormone during pregnancy.

Elevated irCRH levels up to 14 ng/ml were measured in 176 females in the last trimester. The highest maternal CRH levels were found in those females in whom the period from the onset of labour to full dilatation of the cervix and the time span of delivery were shortest. irCRH in amniotic fluid (120 +/- 180 pg/ml; n = 14) was in the same range as in umbilical cord plasma (233 +/- 188 pg/ml; n = 66) and 20-fold lower than in prepartal maternal plasma (5.38 +/- 4.49 ng/ml; n = 66). irCRH in maternal plasma correlated highly to irCRH in umbilical cord plasma (p less than 0.001; n = 66). After delivery irCRH disappeared from maternal plasma with a half-life of 50 minutes (n = 14). One day postpartum irCRH levels (n = 22) were undetectable. The height of the irCRH levels in the various biological fluids did not correlate to the mode or the pathological events of delivery (n = 43). Maternal ACTH levels above the normal range were encountered only in women immediately prepartal and did not correlate to the CRH levels (253 +/- 229 pg/ml; n = 66). Cortisol levels were higher in maternal plasma than in umbilical cord plasma due to elevated CBG (n = 78). Free cortisol levels were higher in the 3rd trimester than in the 1st (2.18 +/- 0.16 vs 1.16 +/- 0.73 ng/ml; n = 42). irCRH in maternal and umbilical cord plasma correlated to the hPl and estriol levels (p less than 0.001 and p less than 0.05; n = 66). We conclude that irCRH is secreted by the placenta into both maternal and fetal circulation. Though placental CRH is undistinguishable from hypothalamic CRH, the biological significance of placental CRH remains open. Our data show that placental CRH might be responsible for the changed function of the adrenal gland during pregnancy, with higher free cortisol levels in the last trimester. The extremely elevated ACTH levels during labour and delivery indicate that CRH is not the only mediator of stress-induced ACTH secretion in the regulation of the maternal hypothalamo-pituitary-adrenal axis.

Adolescent↗
PubMed1989

Glucose measurement in diluted blood.

The sensitivity, measuring range and lifetime of enzyme electrodes using glucose oxidase sandwiched between dialysis membranes or alternatively in a polyurethane layer directly on the surface of a platinum electrode are compared. The GOD modified electrode exhibits the highest sensitivity. However, the signal depends strongly on the stirring rate. Using the sandwich membranes up to 120 diluted blood samples per hour with a serial coefficient of variation below 1% can be analyzed.

Biosensing Techniques↗
PubMed1987

Metabolism of exogenous 4- and 2-hydroxyestradiol in the human male.

The metabolic fate of the isomeric catecholestrogens 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol (2-OHE2) was studied to elucidate possible differences in their metabolism as an explanation for their different bioactivities. Healthy young men (n = 3 each) were infused (90 min) with 4-OHE2 (60 micrograms/h) or 2-OHE2 (100 micrograms/h). The main metabolites were determined in plasma and urine before, during and after infusion. Unconjugated and conjugated steroids, the latter after hot acid hydrolysis, were subjected to chromatography on LH-20 columns and measured by specific RIAs. During the infusion 4-OHE2 reached significant plasma concentrations whereas 2-OHE2 was so rapidly metabolised that its plasma levels remained virtually undetectable in spite of a higher infusion rate. The metabolism of 4-OHE2 was dominated by direct conjugation, that of 2-OHE2 by methyl ether formation. These findings were corroborated by the urinary excretion rates: during the infusion and the first hours afterwards, 4-OHE2 was mainly excreted as 4-OHE2 and 4-hydroxyestrone, while 2-OHE2 was predominantly excreted as 2-hydroxyestradiol 2-methyl ether and 2-hydroxyestrone 2-methyl ether.

Adult↗