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Biomedical subjects

M Hofmann

Publications and source records attributed to M Hofmann.

At least 217 records · Page 12Linked to original sources
PubMed1988

Frontal chewing patterns of the incisor point and their dependence on resistance of food and type of occlusion.

This study has shown that mastication in normal dentate subjects is associated with a great variety of movement modes. The dependence of chewing patterns on the resistance of food proves that the chewing system is capable of marked variations. A complete assessment of chewing behavior therefore demands the use of both tough and soft foods. Physiologic chewing of tough food is dominated by angulated grinding-type movements, whereas soft consistencies are chewed with drop-shaped or lenticular patterns. In a random sample of patients with good chewing function, approximately 95% of Angle class I and II occlusions were found, which statistically differed neither in chewing pattern distribution nor in movement parameters. As shown in this study, certain occlusal or functional properties cannot be characterized by a single type of chewing pattern but instead by a specific distribution of patterns. As a basis for the evaluation of such investigations, a method for the classification and ordered documentation of observed movement modes is necessary. The scheme used here includes all types of chewing movements that have been presently observed. It permits the recognition of patterns and the quantitative description of their frequencies and variations.

Adolescent↗
PubMed1988

Monoclonal antibodies specific for human cardiac myosin: selection, characterization and experimental myocardial infarct imaging.

Radiolabelled anti-myosin antibodies (AM Ab) specifically accumulate in necrotizing myocytes and, therefore, allow the scintigraphic detection of myocardial infarction. In order to provide a constant supply of myosin-specific antibodies, the somatic cell fusion technique was used for the selection and propagation of AM Ab. Out of 126 antibody producing cell lines, nine were selected for further subcloning, due to their high affinity for purified myosin. For the in vivo imaging, two IgG-antibody molecules appeared particularly useful based on their antigenic specificity as assessed by immunoblotting and indirect immunofluorescence technique. After radiolabelling with iodine-123, undigested antibody molecules or their Fab fragments were injected into 10 dogs with experimental myocardial infarction. The accumulation of radioactivity in myocardial infarction was assessed by in vivo imaging and in vitro scintigraphy of ventricular slices stained by tetrazolium. The use of undigested AM Ab resulted in a high uptake ratio of radioactivity in the infarcted as compared to normal myocardium (20:1). In vivo infarct imaging, however, was not possible due to sustained labelling of the blood pool. The uptake ratio of iodine-123 labelled Fab fragments was only 9:1, but due to a faster plasma clearance of the Fab fragments, uptake in the heart could be visualized 5 h after intravenous injection. Clear differentiation between infarcted and noninfarcted myocardium, however, was limited by accumulation of radioactivity in the thoracotomy wound, in the liver, and in the stomach.

Animals↗
PubMed1988

Propagation of the virus of porcine epidemic diarrhea in cell culture.

Porcine epidemic diarrhea virus (PEDV) was adapted to serial propagation in Vero cell cultures by adding trypsin to the medium. PEDV-infected cells showed a distinct cytoplasmic fluorescence when examined by a fluorescent-antibody-staining technique. Cytopathic effects, such as vacuolation, formation of syncytia, and fusion of cells, were detected even at passage 1 of the PEDV in Vero cells. Once adapted, the virus induced numerous syncytia containing over 100 nuclei. From virus passage 5 on, all cells forming the monolayer were fused and totally destroyed within 24 h after inoculation. Cell culture-grown PEDV had typical coronavirus morphology when viewed by electron microscopy. Attempts to propagate PEDV in several primary and secondary fetal porcine cell cultures in the presence or absence of trypsin were unsuccessful.

Animals↗
PubMed1988

[Effect of class I anti-arrhythmia agents on the signal-averaged ECG].

This study was designed to determine which parameters in the signal-averaged ECG are subject to the influence of class I antiarrhythmic agents and whether the effects on these parameters differ with respect to the various subgroups of agents within the class I antiarrhythmics. For this purpose, disopyramide was chosen as representative of class Ia, tocainide Ib and flecainide Ic. A total of 23 patients, twelve with coronary artery disease and eleven with dilated cardiomyopathy and high grade ventricular arrhythmics, received randomized and single-blind, placebo-controlled high single oral doses of 300 mg disopyramide, 800 mg tocainide and 300 mg flecainide with a washout period of five half-times of the antecedent drug prior to the subsequent agent. Before and two hours after the respective drugs the signal-averaged ECG was recorded. The position of the electrodes was unchanged throughout the study. A total of 142 recordings were performed. Computerized calculation of the duration and mean voltage of the entire filtered QRS complex and the voltage during the last 40 and 50 ms, respectively, was carried out according to the method of Simson. Additionally, according to a modification by Karbenn, the duration and voltage of late potentials were analyzed. In the baseline signal-averaged ECG, 13 of 23 patients (57%) had late potentials. Of the 18 patients who received disopyramide, ten had late potentials before and after the drug. In seven, late potentials were not present either before or after the drug. In one patient with a negative finding at baseline, late potentials were observed after disopyramide. There was a significant increase in the duration (p less than 0.001) as well as a decrease in the voltage of the entire filtered QRS-complex (p less than 0.01) and the voltage during the last 40 and 50 ms, respectively (p less than 0.05). Late potentials were present before and after tocainide in nine of 18 patients (50%) who received this drug. In the remaining 50%, late potentials were not observed either before or after the drug. Comparison of mean values before and two hours after 800 mg tocainide showed no significant changes for duration or voltage of the entire filtered QRS-complex nor for the voltage during the last 40 and 50 ms, respectively. Before and after flecainide, eight of 17 patients had late potentials (47%).(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Arrhythmia Agents↗
PubMed1987

Delay of development of transmural irreversible ischaemic injury in canine myocardium.

During the course of experimentally induced myocardial ischaemia affected tissue initially suffers reversible ischaemic injury or, if ischaemia persists, injury of increasing severity before becoming irreversibly damaged. This state is characterized by tissue necrosis and referred to as myocardial infarction. The purpose of this study was to investigate whether it is possible to delay or perhaps even prevent the development of irreversible ischaemic injury. Ischaemia was induced by coronary artery occlusion (CAO) in canine hearts for 90 min or 24 h. The drug used for intervention was hyaluronidase. Ischaemic damage was assessed by p-NBT staining and ultrastructural evaluation of tissue biopsies. Development of irreversible ischaemic damage was prevented during 90 min of CAO. However, progression of reversible to irreversible ischaemic injury could not be prevented during 24 h of CAO. In conclusion, it is possible to prevent the development of irreversible ischaemic injury by a suitable intervention during the early stages of ischaemia in the canine heart and thus to gain time for additional intervention in the early treatment of myocardial infarction.

Animals↗