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Biomedical subjects

H Weber

Publications and source records attributed to H Weber.

At least 397 records · Page 22Linked to original sources
PubMed1984

[Antiarrhythmic effect and side effects of amiodarone].

UNLABELLED: Amiodarone (AM) is one of the most potent antiarrhythmic drugs, the value of which is limited by reversible and irreversible side-effects (SE). 59 patients, 50 male, 9 female (age 33 to 81 years) entered the study with ventricular tachycardia (VT, 68%), WPW-tachycardia (12%), non-sustained VT (12%) or untreatable paroxysmal atrial fibrillation or supraventricular tachycardia (8%). Prior to AM the patients had received 1 to 8 different antiarrhythmic drugs (m 3.5) and maximal 9 different combinations of antiarrhythmics. The drug regimen started with a loading dose of 1200 mg/d for 1 to 2 weeks and was continued with a maintenance dose of 200 to 600 mg/d. The patients were followed up 1 to 41 months (m 14 m). The drug effect was evaluated using clinical criteria (recurrence of arrhythmias, death), computer-assisted analysis of several 24 hr long-term ECGs and programmed electrophysiological stimulation. Three- to six-monthly the patients were seen in our outpatient department for check up and blood-sample analysis (liver, thyroid gland etc.). Also in the majority of the patients frequent ophthalmological and dermatological investigations, as well as lung functions tests were carried out. RESULTS: under AM therapy the initial arrhythmias were no longer detectable in 41% of the patients. In 37% a significant amelioration of the formerly life-threatening arrhythmias was found. 7 patients (12%), predominantly with reduced left ventricular function, died during follow up. No pulmonary, hepatotoxic or neurological SE were found. All patients developed reversible AM keratopathy. In 27% ETR and T4 were elevated, but only one patient developed hyperthyroidism with an increase in TT3. Another patient showed signs of hypothyroidism with an elevated TSH prior to TRH stimulation. Increased phototoxicity was found in 31%, whereas in two patients typical AM hyperpigmentation occurred, especially on the face. In conclusion, AM is a highly effective antiarrhythmic agent, despite a negatively selected collective, but it should only be used in patients with refractory arrhythmia in view of the SE.

Adult↗
PubMed1984

alpha-Alkyl-alpha-arylacetic acid derivatives as fluorescence markers for thin-layer chromatographic and high-performance liquid chromatographic assay of amines and alcohols.

Activated R,S-benoxaprofen is described as a new reagent for fluorescent derivatization of drugs with primary or secondary amino groups or with hydroxyl groups. Separation of the reaction products is demonstrated by thin-layer chromatography and high-performance liquid chromatography. The sensitivity of the detection is in the picomole range. Derivatization procedures can be easily and rapidly performed.

Air↗
PubMed1984

[Value of ECG-telephone transmission in determining symptomatic heart-rhythm disorders].

The ECG-telephone-transmission (TTM) was used to record an ECG-strip during a typical symptomatic period in patients complaining of symptoms possibly caused by arrhythmias (palpitations, dizziness, paroxysm tachycardia, pulse irregularities; angina and dyspnea only if other reasons could be excluded). Patients complaining of syncope only were not admitted, because of the inability to make a telephone call successfully during such a symptomatic period. The ECG was transmitted to the CCU using a frequency modulation technique. In 60% of 196 patients an ECG-TTM could be achieved during a typical symptomatic period, whereas arrhythmias as cause for the symptoms could be excluded in 51 patients (26%). The remaining 66 patients (34%) demonstrated various arrhythmias ranging from simple SVPB and PVC to total AV-block and sustained VT. TTM, an easy-to-perform and cost-effective method allowed a successful ECG registration during a symptomatic period in almost two-thirds of symptomatic patients. In these patients arrhythmias could be verified or excluded as cause of the symptoms.

Adolescent↗
PubMed1984

[Vagus block in the therapy of bradycardial arrhythmias--the role of autonomic balance].

UNLABELLED: A medicamentous therapy of bradycardiac disturbances of heart rhythm can be performed on the one hand by stimulation of the sympathetic nerve, on the other hand by blockade of the parasympathetic system. An ester of the tropic acid, Ipratropiumbromide (IP), shall be used for answering the question to what extent the heart rate may be increased in such arrhythmias. In 10 patients (4 females and 6 males, m 60 +/- 9 years old) with asymptomatic bradycardiac arrhythmias (heart rate less than 60 per min in the routine ECG; 3 patients AV-block III, 1 patient AV-block II II, 6 patients sinus bradycardia) at first a 24-hour long-term ECG was recorded under ambulatory conditions, after this 1 mg IP was administered intravenously under continuous long-term ECG. After 4 days 10 mg IP orally thrice a day, in 3 patients also after 15 mg IP t.i.d. a repeated long-term ECG was performed. These were evaluated using the computer-assisted "multipass scanning" system. RESULTS: 1 hour after 1 mg IP intravenously the m heart rate significantly increased about 17-87% (m 55%) in all patients (p less than 0.001). Proportionally to the increase of the heart rate it lasted 7-14 hrs. till the initial heart rate was reached again. 1-4 hours after intravenous injection in 2 patients sinus tachycardias developed as an expression of an increased sympathicotonia. 10 mg IP led to an increase of the heart rate of m 8% of the patients, during the day m 9%, during the night 4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Activated alpha-alkyl-alpha-arylacetic acid enantiomers for stereoselective thin-layer chromatographic and high-performance liquid chromatographic determination of chiral amines.

The separation of racemic benoxaprofen into the two benoxaprofen enantiomers by preparative high-performance liquid chromatography and the application of the activated enantiomers as derivatization reagents for the simultaneous stereoselective determination of chiral amines in biological material is described. Activated (+)- and (-)-benoxaprofen are both shown to be very sensitive and stable chiral fluorescence markers, applicable to thin-layer chromatography as well as to high-performance liquid chromatography.

Amines↗
PubMed1984

[Ultrasonics and computerized tomography in the diagnosis of large cavernous hemangiomas of the liver].

Cavernous haemangiomas of the liver often pose problems in the differential diagnosis on ultrasound because of the complex echo pattern. Some typical features of their sonomorphology are exemplified by the data obtained in 4 patients. In combination with the almost pathognomonic delayed contrast enhancement on computed tomography, additional angiography seems to be no longer necessary for an accurate diagnosis in most cases.

Angiography↗
PubMed1984

Teratogenicity of 2.3.7.8-tetrachlorodibenzofuran (TCDF) in mice.

Treatment of pregnant C57BL/6N mice with 2,3,7,8-tetrachlorodibenzofuran (TCDF) (0, 250, 500, and 1000 micrograms/kg on gestation day 10 or 0, 10, 30, 50, and 100 micrograms/kg on gestation days 10-13) results in dose-related increases in isolated cleft palates and hydronephrotic kidneys in the offspring. TCDF is teratogenic in 100% of the fetuses at dose levels that are not maternally toxic. The fetal kidney is the most sensitive target organ but the kidney lesions may be reversible.

Abnormalities, Drug-Induced↗
PubMed1984

The preoperative and postoperative findings in 627 patients with tetralogy of Fallot.

The preoperative and postoperative findings in 627 patients operated for correction of tetralogy of Fallot (TOF) in the period 1960 to 1984 were analyzed in order to evaluate the clinical and hemodynamic late results. The average age was 7.2 years (range 9 months to 30 years). The patients were divided into 4 groups in order to determine the long-term prognosis in relation to the severity of the underlying anatomy; group I = without outflow tract patch; group II = with a patch up to the valve base; group III = with a transannular patch (TAP); group IV = TAP or valved conduit in patients with pulmonary atresia. Preceding shunt operations had been performed in 350 patients (55.8%); a primary correction was carried out in 277 cases (44.1%). Hospital mortality for all patients operated from 1960 to 1984 was 14.0%, late mortality, by contrast, was only 1.1%. In the last 4 years (1980 to 1983), the overall mortality considerably decreased to 3.4% (n = 29) for patients without TAP and to 8.0% for all operated patients including those with pulmonary atresia (n = 50). A comparison of the actuarial survival curves, moreover, demonstrates that the prognostic survival rate is unequivocally dependent on the severity of the anatomy of a TOF. The hemodynamic results obtained from 271 recatheterized patients from all 4 groups were designated excellent in 106 patients (39.1%), good in 100 (39.9%) and poor in 65 (23.9%). Proximal residual gradients across the right ventricular outflow tract (RVOT) were found in 30.2% of the corrected patients, and distal gradients in 24.3%. Fifty-two patients out of the 627 (8.2%) had to be reoperated for residual VSD, RVOT aneurysm, valvular pulmonary stenosis or peripheral stenosis. Intracardial electrophysiological tests carried out in 166 patients postoperatively showed an antegrade effective refractory period of the AV-node lasting over 400 ms in 47 patients (28.3%), as well as additional ventricular action potentials in 117 patients (70.4%), which could be correlated to extrasystoles or ventricular tachycardia in 37.9% of the cases. Additional AV-pathways were disclosed in 3 patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1984

Diagnostic value of exercise testing versus long-term ECG in evaluation of arrhythmias in old age.

The usefulness of exercise testing (ET) in old age is so far undefined particularly for detection of arrhythmias. We compared the diagnostic value of ET with 24-h long-term ECG recording (LT-ECG) in patients older than 70 years that were evaluated because of symptoms possibly related to arrhythmias. In 37 patients (age 72.8 +/- 2.7 years) the incidence of ventricular arrhythmias (LOWN greater than or equal to 1) was greater during ET (67%) than during 24-h LT-ECG recording (48%, P less than 0.01). Complex ventricular arrhythmias were detected in 6/37 patients (16%) by ET, in 9/37 patients (24%) by LT-ECG, in one patient (3%) by both tests and in 14/37 patients (37%) by one of the two tests, while 23/37 patients (63%) had no significant complex arrhythmias recorded by either test. During ET 12 patients (32%) showed signs of myocardial ischaemia with ST-depression greater than or equal to 0.2 mV and/or increasing angina pectoris. In 42% of these patients complex ventricular arrhythmias LOWN greater than or equal to 3 occurred during ET. Thus both ET and LT-ECG are useful methods to uncover arrhythmias in symptomatic patients older than 70 years and have to be considered as complementary tools.

Aged↗
PubMed1984

Characterization of alpha-ketobutyrate metabolism in rat tissues: effects of dietary protein and fasting.

The oxidative decarboxylation of alpha-ketobutyrate was studied in rat tissue preparations. Decarboxylation was confined to the mitochondrial fraction and required coenzyme A, NAD, TPP and FAD for optimal activity in solubilized preparations. The pH optimum for this reaction in liver was 7.8, somewhat higher than that reported for other alpha-keto acid dehydrogenases. An apparent Km of 0.63 mM for alpha-ketobutyrate was determined for the rat liver system. Competition by other alpha-keto acids at 10 mM concentrations inhibited enzyme activity up to 75%. Tissue distribution of alpha-ketobutyrate dehydrogenase activity relative to liver activity was (in percent): liver, 100; heart, 127; brain, 63; kidney, 57; skeletal muscle, 38; and small intestine, 7. Total liver alpha-ketobutyrate dehydrogenase was decreased by 40% after a 24-hour fast. Similar results were found for kidney and heart activity. alpha-Aminobutyrate-pyruvate aminotransferase activity in liver or kidney was not affected by fasting; however, it was induced in liver by 50% after feeding a 40% casein diet for 10 days compared to rats fed a 20% casein diet. Increasing the dietary casein content from 6 through 40% of the diet resulted in about a fivefold increase in liver alpha-ketobutyrate dehydrogenase activity. The substantial extrahepatic capacity for alpha-ketobutyrate metabolism makes it unlikely that a loss of liver function results in an inability to metabolize alpha-ketobutyrate. Whether alpha-ketobutyrate is decarboxylated by a specific enzyme or by an already characterized complex such as pyruvate dehydrogenase or the branched-chain keto acid dehydrogenase remains to be established.

Aminobutyrates↗
PubMed1984

Pacemaker-mediated tachycardias: a new modality of treatment.

Three patients with pacemaker interactive drug resistant tachycardia underwent invasive electrophysiological studies. In the first patient, the retrograde conduction of the artificial reciprocating tachycardia was provided by two right-sided accessory pathways and the antegrade conduction by an atrial synchronous pulse generator. In addition, AV-nodal tachycardia occurred alternately. In the second patient with intermittent atrial flutter, the AV node and, coincidentally, an AV sequential pulse generator provided high-rate antegrade conduction to the ventricles. In the third patient with surgical complete heart block, intermittent AV-nodal tachycardia induced retrograde atrial activation while an atrial synchronous pacemaker provided the antegrade conduction. Electrode catheter exploration of the heart allowed localization and closed-chest ablation of the accessory pathways or AV node by delivering two to seven 200-joule direct-current shocks through the appropriate electrode of the exploring catheter. Thereby, pacemaker-mediated arrhythmias could be controlled in these patients in the follow-up of 6 to 8 months.

Adult↗
PubMed1984

Chronic hemodialysis: high risk patients for arrhythmias?

UNLABELLED: Patients with end-stage kidney disease undergoing chronic maintenance dialysis (HD) are a high risk group for sudden death due to cardiovascular complications. It was the aim of the study to investigate the quantity and quality of arrhythmias during HD and between two consecutive HD (interval, I) with regard to the reproducibility of the expected results. 15 patients (8 males, 7 females) underwent continuous Holter monitoring (LT-ECG) under ambulatory conditions over 96 h including two HD ( HD1 + HD2 ) and two intervals (I1 + I2). The LT-ECG recordings were analysed with the computer assisted ' Multipass -Scanning' system with regard to heart rate (HR), supraventricular premature beats (SPB), ventricular ectopics (PVC) and malignant ventricular arrhythmias. RESULTS: The HR demonstrated a typical, well-known circadian pattern with remarkable increase of the HR during each HD. Except for rare, single SPB and/or PVC, no supraventricular or ventricular arrhythmias could be detected reproducibly. Single PVC occurred in patients with a lower potassium value. No malignant ventricular arrhythmias were found. In comparison to previously published studies, which demonstrated a high incidence of malignant ventricular arrhythmias, these conflicting results were due to differences in patients' recruitment (underlying disease, age, etc.), the performance of HD (duration, ion concentration of the dialysate etc.), serum potassium levels and drug medication (digitalis, quinidine). In summary, chronic HD per se did not enhance the risk of malignant arrhythmias in patients with end-stage kidney disease.

Adolescent↗
PubMed1984

Use of nystatin for random spore selection in the yeast Saccharomycopsis lipolytica.

Nystatin was used to develop a new method to select spores of the yeast Saccharomycopsis lipolytica. At low concentrations nystatin killed preferently growing cells of this yeast. At high concentrations nongrowing cells were affected as well. In contrast, spores were not sensitive to nystatin action. This differential response to the antibiotic suggested its use to select spores from sporulated yeast cultures.

Ascomycota↗
PubMed1984

[Diagnosis of syncopes in suspected arrhythmias].

Several mechanisms lead to attacks with unsuspected sudden and intermittent loss of consciousness. A major cause for such syncopes are arrhythmias. Only in rare cases it is possible to register an ECG during a typical attack despite many newer methods as long-term ECG (LT-ECG), exercise stress test and electrophysiologic investigations. LT-ECG does not record the ECG only during symptomatic periods (syncopes, dizziness, palpitations etc), but also registers asymptomatic AR, which can be precursors of SY. Carotid sinus massage is a valuable tool for the detection of a cardio-inhibitory Carotid-Sinus-Syndrome, which can be treated with PM-implantation. Exercise stress testing induces ventricular arrhythmias, which also indicates AR as underlying cause for SY. Using the invasive electrophysiologic investigation methods the importance measuring supraventricular parameters (SNRT, SA-, AH-interval) or parameters of the AV-nodal conduction (AH-, HV-interval) decreased in contrast to the ventricular stimulation techniques. With these invasive procedures ventricular tachycardias, ventricular flutter or fibrillation can be induced in selected patients, which indicates also a possible arrhythmogenic substrate for SY. In a suspected arrhythmogenic genesis of SY it has to be recommended to perform LT-ECG, carotid sinus massage, exercise stress testing and -- in selected patients -- electrophysiological investigations in addition to the routine-ECG to exclude or confirm arrhythmias as possible substrate for SY.

Arrhythmias, Cardiac↗
PubMed1984

[Thyroid functional parameters during anti-arrhythmia therapy with amiodarone].

Thyroid function was investigated in 41 patients on chronic treatment with amiodarone. 27% of the patients had elevated total thyroxine levels together with elevated free thyroxine levels. Thyrotropin (TSH) secretion was completely suppressed in 15% of the patients. Elevated free or total thyroxine levels were frequently observed together with normal TSH secretion, although 5 of the 6 patients with suppressed TSH had markedly elevated levels. Triiodothyronine (T3) levels were low normal or below the normal range in all patients but one. This was the only patient who apparently developed amiodarone-induced hyperthyroidism. The clinical symptoms of this patient were equivocal. Thyroid function parameters including T3 levels returned to normal only 3 months after withdrawal of the drug. The patient did not need any thyrostatic treatment. The duration of treatment with amiodarone did not influence thyroid hormone concentrations, although there was an insignificant trend of increasing total thyroxine levels after a year of treatment. There was, moreover, no significant influence of the dose (200-500 mg orally/day) of amiodarone on thyroid hormone levels. Our results show that the usual screening parameters of thyroid function, namely total and free thyroxine serum concentrations, are not reliable in patients on chronic amiodarone treatment. The incidence of amiodarone-induced hypothyroidism was 2.4%. We did not observe an amiodarone-induced hypothyroidism, although there was one patient with increased TSH levels but normal T3 and thyroxine levels.

Adolescent↗