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Biomedical subjects

H O Klein

Publications and source records attributed to H O Klein.

At least 91 records · Page 5Linked to original sources
PubMed1982

The supernormal phase of intraventricular conduction: normalization of intraventricular conduction of premature atrial beats.

This report presents the analysis of a case in which numerous atrial extrasystoles, associated with normal intraventricular conduction, occurred during sinus rhythm conducted with right bundle branch block. The wide overlap of coupling intervals of normally conducted extrasystoles and other extrasystoles with right bundle branch block seemed prima facie to negate the possibility of supernormality. Rearrangement of these intervals, however, to allow for the timing of right bundle branch depolarization with respect to the ensuing QRS complex, resulted in a clear cut separation of all normalized complexes from those with right bundle branch block. All normalized extrasystoles were localized in a zone very early in the cycle. This finding, in the presence of atrial extrasystoles with normal P-R intervals, strongly supports the mechanism of supernormality in this case. Alternate explanations do not appear to be tenable.

Aged↗
PubMed1982

The influence of verapamil on serum digoxin concentration.

The effect of verapamil on the pharmacokinetics of digoxin was studied in 49 patients with chronic atrial fibrillation. A dose of 240 mg/day of verapamil was given to the patients who were receiving a stable dose of digoxin. Serum digoxin levels rose from 0.76 +/- 0.54 ng/ml (mean +/- SD) to 1.31 +/- 0.54 ng/ml during verapamil treatment (p less than 0.0005). This effect was dose-dependent, as shown in seven subjects who received 160 mg and then, 240 mg of verapamil: There was a stepwise rise in serum digoxin concentration from a control value of 0.60 +/- 0.11 ng/ml to 0.84 +/- 0.18 ng/ml and 1.24 +/- 0.40 ng/ml, respectively (p less than 0.01 for both steps). The effect of verapamil developed gradually within the first few days in seven subjects in whom serum digoxin concentration reached, within 7 days, 90% of the increase observed 14 days after onset of verapamil. Renal digoxin clearance decreased significantly (26.1 +/- 0.7 vs 55.1 +/- 12.3 ml/min, p less than 0.005) in six patients in whom serum digoxin concentration increased. It did not change in one patient in whom serum digoxin concentration was not influenced by verapamil. Creatine clearance did not change in any of these seven. The same effects on digoxin clearance were observed in three normal subjects. Among the 49 patients, verapamil resulted in the development of signs and symptoms that suggested digitalis toxicity in seven. Verapamil significantly increased serum digoxin concentration. The process is dose-dependent and gradual, and it is at least partially explained by reduced renal excretion without reduction in glomerular filtration. The dose of digoxin may need readjustment in patients who are concomitantly receiving verapamil.

Adult↗
PubMed1981

The use of the balloon-tipped floating catheter in temporary transvenous cardiac pacing.

The effectiveness and safety of balloon-tipped, flow guided, electrodes for ventricular pacing as opposed to the fluoroscopy-guided semi-rigid bipolar electrodes have never been compared in a controlled study. A prospective study was therefore undertaken to compare both techniques in semi-elective and emergency procedures. Flow guided electrodes were inserted in 67 patients (group A) and semi-rigid electrodes in 44 patients (group B). The results of group A were judged to be superior to those of group B in four aspects: a) shorter time (6'45" vs. 13'30", p less than 0.0005); b) lower incidence of catheter displacement (13.4 vs. 32.0 percent, p less than 0.05); c) longer interval of time between implantation and catheter displacement (4.4 vs. 1.9 days, p less than 0.0005); d) lower incidence of serious ventricular arrhythmias during insertion (1.5 vs. 20.4 percent, p less than 0.005). Threshold at insertion was not significantly different (0.6 +/- 0.3 vs 0.7 +/- 0.2 milliampere). The superiority of flow-guided electrodes over fluoroscopy-guided electrodes persisted in the comparison of semielective insertions in groups A and B. We conclude that the flow-guided insertion technique is safer, more expeditious and more stable than the fluoroscopy-guided technique in semi-elective as well as in emergency insertions.

Adolescent↗
PubMed1981

Mid-systolic click and echocardiographic evidence of mitral valve prolapse during electrical pacing.

A mid-systolic click was present in a patient during three years of follow-up after implantation of a permanent transvenous pacemaker. Echocardiography revealed posterior motion of the anterior leaflet which resembled mitral valve prolapse. Both the click and echocardiographic evidence of prolapse disappeared simultaneously with resumption of sinus rhythm and during supraventricular tachyarrhythmias. Wtih spontaneous change in the position of the electrode three years after initial implantation, both the click and the posterior motion of the mitral valve disappeared. The association of mitral valve prolapse with electrical pacing is most unusual and appears to have a distinct pathophysiological mechanism.

Aged↗
PubMed1980

The significance of lectin receptors in the kidney and in hypernephroma (renal adenocarcinoma).

Normal kidney tissue as well as hypernephromas were examined histochemically for the occurrence of lectin receptors. FITC- and rhodamine-labeled peanut agglutinin (PNA) and Ricinus communis agglutinin (RCA) were used for labeling different carbohydrate residues which may be of interest in the evaluation of the histogenesis of hypernephromas and possibly for concepts regarding the immunotherapy of these tumors. By using fluorescence microscopy, the receptor for PNA was found on the epithelial cells of the thin limb, distal convoluted tubules, and the collecting ducts. These binding sites occurred in a free as well as in a sialic-acid-substituted form and were mainly exposed on the luminal surface of the epithelial cells. They were absent, however, in the proximal convoluted tubules. This finding contrasts with the demonstration of RCA receptors in the brush border of these tubules. Moreover, RCA reacted with the epithelial cells of all tubules. The hypernephromas showed a wide range in the distribution and the quality of the lectin receptors, which were localized within the cytoplasm as well as in the cell membrane of the tumor cells. As demonstrated by our histochemical investigations, these kidney neoplasms may originate from any part of the tubules, and not only from the epithelial cells of the proximal convoluted tubules, as was suggested by earlier findings that employed antibodies against the brush-border antigens. In addition, the demonstration of sialic-acid-substituted and, in particular, of free PNA-receptors, which represent the immunodominant group of the Thomsen-Friedenreich antigen, may supply useful information on an immunotherapy concept.

Adenocarcinoma↗
PubMed1980

Experimental investigations on a sequential combination chemotherapy protocol.

This paper deals with experimental investigations concerning the composition of a cytostatic three-drug-protocol in diploid Ehrlich-Ascites-Tumor (EAT) cells in vivo at a far advanced stage of the disease. Hydroxyurea (HU) and vincristine (VCR) were used in very low doses to induce a modification of the growth pattern of tumor cells alike partial synchronization. Adriamycin (ADM) was selected as cytocidal drug during DNA synthesis of the partially synchronized cells. It was found that the sequential combination of HU and VCR (first HU and 12 h thereafter VCR) caused the greatest alteration of growth pattern compared with other combination protocols. A further statistically significant increase of the degree of synchrony was observed after a second VCR administration -- 22 h after HU. By means of this protocol the EAT was subdivided into two proliferating subpopulations, a diploid and tetraploid one. The tetraploid population resulted from surviving cells being not able to perform dytokinesis correctly, so that polynuclear cells and cells with a large single nucleus containing tetraploid DNA values were created. With respect to therapy, the administation of ADM at the time of DNA synthesis of the partially synchronized cells resulted in a statistically significant prolongation of the mean survival time and in 30% of cures of the animals. The dosage of ADM was 2.6 mg/kg, i.e., a nonlethal dose (50% of the LD10). Other combinations, i.e., simultaneous or reversed sequential combinations, did not show any therapeutic improvement compared to single drug therapy of ADM.

Animals↗
PubMed1980

Permanent overdrive pacing for the suppression of recurrent ventricular tachycardia in a newborn with long QT syndrome.

A newborn with long QT interval and repetitive ventricular tachycardia of the "torsade de pointes" type was seen at the age of one day. The arrhythmia was resistant to lidocaine, propranolol and atropine, but was controlled by isoproterenol infusion. A transvenous pacemaker, inserted at three days of age, suppressed the ventricular tachycardia at stimulation rates above 100/minute. At 19 days of age a permanent pacemaker at pulse rate of 119 beats/minute was implanted. At one year of age the infant was thriving and was completely free of ventricular arrhythmia.

Cardiac Pacing, Artificial↗
PubMed1980

Cell kinetic alterations in normal and neoplastic cell populations in vitro and in vivo following vincristine: a reply to Dr Camplejohn's review article.

It is shown that the lethal action of vincristine (VCR) is dose-dependent and may occur at interphase and mitosis. In general, the VCR dose used to destroy cells must be approximately ten times higher than that used to arrest cells in mitosis at metaphase. There is strong evidence that cells can survive metaphase arrest by a sublethal dose of VCR either completing cytokinesis normally after metabolism of the drug or becoming polyploid because of an impaired mitotic spindle apparatus. These cells are not doomed to die, at least in some cell systems. Furthermore, there is strong evidence in three animal tumour systems (transplantable and autochthonous tumours) that VCR is able to induce in vivo partial synchronization of proliferating tumour cells and/or recruitment of resting cells into the proliferating compartment. Failures to induce partial synchrony in cell populations by VCR may be attributed to resistance to VCR or cytolysis or slow proliferation of cells in badly vascularized tumours. Chemotherapy after synchronization seems to be effective as shown by non-randomized trials in bad-risk patients with solid tumours and acute leukaemias. In a randomized co-operative trial results of the two-drug synchronization protocol in patients with non-Hodgkin's lymphoma of high grade malignancy were statistically better than those of a four-drug protocol (COPP) established empirically. The two-drug protocol was equally effective as the four-drug protocol in Hodgkin's disease. Side-effects were less pronounced with the so-called synchronization scheme.

Animals↗
PubMed1980

The beneficial effect of the beta blocker timolol in stable agina pectoris.

Timolol is a new beta blocker with cardioselective properties. A single blind controlled study was performed to assess the efficacy of timolol maleate in doses of 10 to 30 mg per day in 20 patients affected by stable angina pectoris. The patients received a placebo for a baseline period of 2 weeks, followed by 12 weeks of timolol. The number of anginal attacks dropped from 14.9 attacks per week in the baseline period to a minimum of 4.6 attacks per week in the sixth week of treatment (P less than 0.01). The number of tablets of nitroglycerin taken per week was reduced from 6.5 during the baseline period to 2.3 in the sixth week of treatment. Resting heart rate decreased from a baseline mean value of 72 beats per minute to 51.7 and 53.7 per minute at weeks 6 and 12 respectively (P less than 0.01). Blood pressure both at rest and during exercise was significantly reduced. The mean work index measured during bicycle ergometry was 127 units before treatment; it increased by 29.4 units and 36.1 units during week 6 and week 12 respectively (P less than 0.05). There was a marked symptomatic improvement in 50% of the patients. Mild fatigue was a common side effect but it disappeared following reduction of dose. We concluded that timolol maleate significantly reduces the number of anginal attacks and increases the work capacity of patients affected by stable angina pectoris

Adrenergic beta-Antagonists↗
PubMed1980

[Partial synchronization and cytostatic combination therapy of disseminated malignant lymphomas of the skin].

Six patients with advanced disseminated malignant lymphomas of the skin were treated with cytostatics using the method of partial synchronisation of the tumor cell growth phases. Though five patients had already shown a resistance against the usual chemo- and/or radiotherapy, all patients responded to this therapeutical principle. Full remission was achieved in four patients. We proved that vincristine effectively synchronizes the growth of proliferating human tumor cells in vivo. Treatment was applied in two steps. First a partial synchronisation of tumor cell growth was induced by vincristine as a pharmacologic means. Then the cytostatics were applied in killing doses at the calculated time. For this purpose we determined the average length of each generation of cells and developed individual therapy schemes. To get the best results with this method usually several therapy cycles were used. In case of a relapse the therapy scheme was adjusted to the altered cellular kinetics. This principal of partial synchronisation is suitable for treating malignant lymphomas with high efficiency, especially those with rapid proliferation even in advanced states.

Adult↗
PubMed1980

Wolff-Parkinson-White syndrome: disappearance of preexcitation and appearance of complete heart block, probably due to myocardial infarction.

The appearance and gradual progression of atrioventricular (A-V) block in the presence of the Wolff-Parkinson-White (WPW) syndrome is an intriguing phenomenon. The vast majority of the reports up to date describe persistence of preexcitation in the face of partial or complete heart block. We describe a patient with severe coronary artery disease, in whom WPW disappeared suddenly, transiently at first, during coronary bypass surgery, and then permanently, probably as a result of an acute myocardial infarction, and in whom all the sinus beats during relentlessly progressive heart block were conducted through the normal A-V conduction system only.

Coronary Artery Bypass↗
PubMed1980

Overdrive pacing in quinidine syncope and other long QT-interval syndromes.

Prolongation of QT interval is associated with repetitive paroxysm of a particular ventricular tachycardia. It is a typical complication of quinidine therapy but may occur in various other conditions. We used endocardial pacing in nine patients with prolongation of the QT interval who suffered from bouts of ventricular tachycardia and fibrillation. In six patients, the syndrome was due to quinidine and in three, to prenylamine. Acceleration of heart rate resulted in immediate suppression of all arrhythmias. Pacing was continued until the condition producing the QT prolongation disappeared. In one case, a permanent pacemaker was implanted, as the QT prolongation was congenital and permanent. The absolute QT interval was shortened by overdrive pacing from a mean value of 0.65 s to 0.50 s. The corrected QT interval remained prolonged (about 0.56 s). Thus, the arrhythmia was associated with the duration of the actual QT interval, and overdrive pacing was able to suppress it without shortening the corrected QT interval.

Adult↗
PubMed1979

Inefficacy of digitalis in the control of heart rate in patients with chronic atrial fibrillation: beneficial effect of an added beta adrenergic blocking agent.

The role of digoxin and the new beta adrenergic blocking agent, timolol, in controlling heart rate at rest and during exercise was investigated in 28 patients with chronic atrial fibrillation. Digoxin failed to prevent excessively rapid heart rates during mild to moderate exercise. Increasing digoxin blood levels from a mean of 0.6 to 1.8 ng/ml had no effect on heart rate either at rest or during exercise. The addition of timolol, 20 to 30 mg/day, resulted in a satisfactory and significant attenuation of the rapid heart rates both at rest and during exercise. Heart rates at rest were 91 and 98 beats/min in the patients with low and high digoxin dosage and rose to 135 and 139 beats/min, respectively, during exercise. Timolol reduced the heart rate to 67 at rest and to 92 beats/min during exercise. The effect of beta adrenergic blockade at rest was less pronounced in patients whose initial heart rates were below 90 beats/min. Digoxin alone may not suffice to control excessive heart rate in patients with chronic atrial fibrillation. The additional beta adrenergic blockade actually normalizes the heart rate response in these patients.

Adrenergic beta-Antagonists↗
PubMed1979

Controlled clinical studies with an antidote against the urotoxicity of oxazaphosphorines: preliminary results.

A randomized study in 20 patients with cancer was carried out to test the clinical efficacy of sodium-2-mercaptoethane sulfonate (ASTA D-7093; mesnum) as an agent to prevent urotoxic side effects (in particular, hemorrhagic cystitis) during cytostatic therapy with the oxazaphosphorines cyclophosphamide and ifosfamide. Eleven patients received mesnum iv and nine patients received a standard prophylaxis. The frequency of microhematuria was significantly lower in the patients receiving mesnum. A slight microhematuria was observed in one patient. With the standard prophylaxis, all nine patients receiving single-agent therapy with ifosfamide or cyclophosphamide had hematuria and three of these had macrohematuria. According to the available results, a daily mesnum dose of 60% (wt/wt) of the ifosfamide or cyclophosphamide dose is recommended. This dose should be divided into three equal fractions. The first administration should be given concurrently with the cytostatic agent and the subsequent two administrations at 4 and 8 hours after administration of the cytostatic agent. Significantly higher doses of mesnum (eg, 133% of the cyclophosphamide or ifosfamide doses) lead to gastrointestinal disorders, which are easily reversible.

Clinical Trials as Topic↗