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Biomedical subjects

M Stöhr

Publications and source records attributed to M Stöhr.

At least 19 recordsLinked to original sources
PubMed1992

Influence of adeno-associated virus on adherence and growth properties of normal cells.

It has been shown previously that infection of newly established cell cultures from malignant human tumors with adeno-associated parvovirus type 2 or type 5 results in growth arrest and cell death. Here we report that the additionally observed antiproliferative effect on diploid human fibroblasts is transient and is connected to a reduced number of cells in S phase. Progression through the cell cycle is disturbed either in G0/G1 or at the G1/S boundary, but an additional arrest in G2 cannot be excluded. DNA synthesis and cell proliferation are resumed when cells are recultured after loosening of cell-matrix adhesions by trypsin treatment. In contrast, they are not resumed by solely providing growth factors via higher amounts of fetal calf serum. The results suggest that cell adherence is altered in adeno-associated parvovirus-infected human embryo fibroblasts.

Cell Adhesion↗
PubMed1992

[The prognostic place of EEG in comparison with evoked potentials in severe hypoxic brain damage].

This retrospective study comprises 34 patients, who died due to the cerebral damage caused by severe anoxia, who were assessed by EEG and AEP or SEP on the same day and in whom at least one of these electrophysiological methods indicated a fatal prognosis. EEG-findings identified 76% of patients with fatal outcome, whereas SEP reliably predicted the outcome in 93% of patients, who died of the cerebral anoxia. In some patients centrally acting drugs made EEG-based but not SEP-based prognosis impossible. In some cases of fatal brain damage, however, only the EEG-findings as opposed to SEP-findings predicted the fatal outcome. Thus the combined assessment by EEG and SEP appears to be optimal in the assessment of an early prognosis. The BAEP were of less prognostic value than the EEG. BAEP findings indicating a fatal outcome were to be found mainly in final clinical stages with loss of brainstem function, whereas EEG as well as SEP identified a considerable number of fatal cases in spite of comparably favourable clinical findings. The evaluation of early electrophysiological testing done within the first 3 days after the anoxic event results in an identical estimation of the prognostic significance of EEG versus BAEP- or SEP-findings, respectively.

Adolescent↗
PubMed1991

In vitro and clinical characterisation of a Newcastle disease virus-modified autologous tumour cell vaccine for treatment of colorectal cancer patients.

A virus-modified autologous tumour cell vaccine prepared from human colorectal cancer cells is described. After dissociation an average of 5 x 10(7) cells/g tissue were obtained from primary tumours and 9 x 10(7)/g tissue from metastases with an average viability of 72% and 51%, respectively. Following irradiation (200 Gy), inactivation of the proliferative activity of the cells was demonstrated by their degeneration in tissue culture and the absence of incorporation of 3H-labelled thymidine. One third of the cells were still metabolically active, as shown by the incorporation of 3H-uridine and a mixture of 3H-aminoacids. The dissociated cells expressed MHC class I and II antigens in a qualitatively similar way to tissue sections. Epithelium-specific antigens (detected by MAb HEA125) were expressed on an average of more than 75% cells of the suspension, while leucocyte-specific antigens (detected by MAb CD53) were expressed on an average of less than 25% cells. The vaccine was prepared by admixing the nonlytic strain Ulster of Newcastle disease virus (NDV) with the tumour cell suspension. The NDV adsorption at tumour cells was shown by electron microscopy. Clinically, the treatment with the vaccine was associated with an increased sensibilisation against autologous tumour cells, measured by DTH skin reactivity. First results in 23 patients with colorectal liver metastases who underwent "curative" liver resection followed by vaccination show a clear correlation between the induced increase of DTH skin reaction against autologous tumour cells and the recurrence-free interval. No correlation was found for DTH reaction caused by standard antigens (Mérieux test), NDV alone or autologous normal liver tissue. The results demonstrate the possibility of preparing immunogenic virus-modified autologous tumour cell vaccine from colorectal cancer tissue, which could be used for cancer therapy.

Adult↗
PubMed1979

Somatosensory evoked potentials following stimulation of the trigeminal nerve in man.

Somatosensory evoked potentials following trigeminal nerve stimulation can regularly be recorded from the contralateral scalp on C5/C6 (10--20 system), a region which overlies the primary face region of the somatosensory cortex. From the first three peaks analyzed (N 13, P 19 and N 26), the first positive peak (P 19) is most prominent and reliable and therefore is recommended for the routine measurements of neurophysiological examination.

Adolescent↗
PubMed1979

Visualization of multidimensional spectra in flow cytometry.

Flow data from a cell sorter have been processed by hardwired circuits which include amplification, discrimination, coincidence requirements, peak sensing and holding, A-D conversion, and a computerized pulse height analysis with storage of the spectra obtained. Two dimensional spectra can be stored directly in memory, on tape and disk. Three and four parametric cellular events can be recorded on line during the flow measurement in a sequential mode on tape for subsequent recall. Simple processing of these data can be performed for displaying of two dimensional projections from these multidimensional spaces based on threshold conditions for the remaining parameters. Interfaced transmission of the stored data to a large scale computer enables more sophisticated data analysis. Data reduction by means of a multidimensional probability analysis has been carried out in order to transfer the spectra to a computerized picture system for display. This system creates perspective two-dimensional images from a three-dimensional data space. Frequency can be converted into grey levels. Hard copy in color (color as the third dimension and color intensity as frequency) simplifies the visualization of multiparametric flow data sets.

Animals↗
PubMed1979

Quantitative cytology of the positive region in flow sorted vaginal smears.

Fifty-one gynecologic specimens were collected from three women's hospitals and mailed in a prefixed status to our laboratory. The specimens were classified into a negative, a suspicious, a postradiation, and a positive group. After single cell dispersion the samples were stained for DNA and protein, analyzed, and sorted in the dual laser equipped Heidelberg flow analyzer sorter (HEIFAS). Particles with elevated DNA values (beyond 3.5 ploidy) and with intermediate protein values were sorted as the positive fraction directly on microscopic slides. After restaining according to Papanicolaou, they were re-evaluated cytologically and identified as tumor cells, dysplastic cells and false alarms. The latter consist of doublets and aggregates of more than two cells, binucleated cells, sperm aggregates and epithelial cells contaminated with bacteria. The different groups showed significant differences regarding the total rate of aggregates to single cells. In general, false alarms were very frequent in the positive region and impeded the statistical classification of the sample. The reduction of false alarms is a prerequisite for prescreening with flow instrumentation.

Cervix Uteri↗
PubMed1979

The Heidelberg flow analyzer and sorter (HEIFAS) approach on the prescreening of uterine cancer.

A dual laser flow system has been proved and used with a novel staining method for simultaneous quantitative DNA and protein analysis. A diamidinophenylindole compound (DAPI) for DNA has been employed in combination with sulforhodamine (SR 101) for protein. With this dye mixture various cell types of the cervical smear could be identified. Despite some overlapping, clusters of leukocytes, endocervicals, (para)basals, intermediates, superficials and dys/neoplastic cells together with artificial events could be discriminated. Up to now the problem of negative cells which create positive signals (false alarms) in the dys/neoplastic region could not be sufficiently solved.

Cervix Uteri↗
PubMed1978

Selective alteration of erythrocyte deformabiliby by SH-reagents: evidence for an involvement of spectrin in membrane shear elasticity.

In order to elucidate the molecular basis of membrane shear elasticity, the effect of membrane protein modification by SH-reaents on the deformability of human erythrocytes was studied. Deformability was quuantified by measuring the elongation of erythrocytes subjected to viscometric flow in a transparent cone plate viscometer. Impermeable SH-reagents proved to have no mechanical effect. Many, but not all, permeable SH-reagents markedly decreased the elongation. Among these, bifunctional SH-reagents (e.g. diamide, tetrathionate and N, N' -p-phenylenedimaleimide) able to cross-link membrane SH-groups were more effective than monofunctional SH-reagents (e.g. N-ethylmaleimide and ethacrynic acid). The bifunctional SH-reagents produced a 50% decrease of elongation after modification of less than 5% of the membrane SH-groups. In contrast, for a comparable effect, more than 20% of the SH-groups had to be modified by the monofunctional reagents. The effect of SH-oxidizing agents was fully reversible after treatment with disulfide-reducing agents. All bifunctional SH-reagents induced a dimerization of a small fraction of spectrin. Anaalysis of the distribution of the diamide-induced disulfide bonds among the various membrane protein fractions showed that this agent preferentially acts on the spectrin polypeptides. The results provide direct experimental evidence that the native arrangement of spectrin is essential for the shear resistance of the erythrocyte membrane and that introduction of small numbers of intermolecular cross-links as well as modification within the molecule lead to a rapid loss of this function.

Diamide↗
PubMed1978

[Myasthenic syndrome during penicillamine treatment (author's transl)].

The clinical and electrophysiological findings in 2 men who had developed a myasthenic syndrome after taking penicillamine for rheumatoid arthritis will be described. The symptoms began with dysfunction of the eye muscles following a generalised muscle weakness. Course of illness after withdrawal of penicillamine was not uniform. In one of the patients a complete remission occurred within a year. The other became steadily worse and required continuous treatment with cholinesterase inhibitors. Electrophysiological examinations showed neuromuscular blockade, posttetanic exhaustion, posttetanic potentiation was found in one patient only. An immunopharmacological block of acetylcholine receptors induced by penicillamine is discussed from a pathogenetical point of view.

Adult↗
PubMed1978

[Brachial plexus paralysis after stellate blockade and plexus anaesthesia (author's transl)].

Brachial plexus paralysis is a serious complication of stellate blockade (n = 2) and plexus anaesthesia (n = 6) as was observed in 8 patients. It is frequently characterised by localised motor and sensory defects in the affected arm and sometimes accompanied by a causalgia-like pain. Pathogenetically mechanical factors--needle trauma, injection pressure, volume, and velocity--are of decisive importance. Prophylactically intraneural injections must be avoided. The electrifying pain during insertion of the needle and (or) immediate anaesthetic effect require correction of needle position.

Adolescent↗
PubMed1978

Normal sensory conduction in the saphenous nerve in man.

Measurements of the sensory conduction velocity and the parameters of nerve action potentials in the saphenous nerve offer many advantages, compared with measurements in other nerves of the leg, regarding accuracy and the time required to complete the investigations. Therefore, the electroneurographical examination of the saphenous nerve is recommended in the early diagnosis of polyneuropathies and is indispensable in the exact diagnosis of proximal neuropathies and lesions of the femoral nerve. In the present study we indicate the proximal and distal segments of the saphenous nerve and illustrate the nerve action potentials from 70 normal subjects.

Adult↗
PubMed1978

Evaluation of eight fluorochrome combinations for simultaneous DNA-protein flow analyses.

Eight fluorescent dye combinations for simultaneous DNA-protein staining have been evaluated spectroscopically and flow microfluorometrically: propidium iodide (PI) with fluoresceinisothiocyanate (FITC), fluorescamine (FC), and dansylchloride (DANS); diamidinophenylindole (DAPII) with sulphorhodamin (SR101), tetramethylrhodamin isothiocyanate (TRITC), and nitrobenzodiazole (NBD); acriflavine (AF) with stilbene isothiocyanate sulphonic acid (SITS), and DAPI. Three different experimental tumor cell lines have been employed in the investigations. Simultaneous DNA-protein analyses have been carried out with the newly developed HEIFAS instrument. Spectroscopically two groups of dyes were distinguishable according to their excitation maximum below 400 nm and above 450 nm respectively. DANS and NBD were found to be unsatisfactory with respect to their protein distributions obtained by flow analysis. The remaining stains involved in the dye combination revealed comparable flow distributions of the cellular DNA and protein content. With respect to preparation time and number of centrifugal steps involved in the staining protocols, and in connection with the stability of the dye used, the DAPI-SR101 method proved to be fastest and easiest. With this combination DNA and protein flow analysis can be performed simultaneously within 30 min.

Animals↗
PubMed1978

Microfluorometric investigations on the cell cycle progression of experimental ascites tumors treated with alkaloidic drugs.

The effects of the antitumor agents vincristine (VCR) and vincaleucoblastine (VLB) on the cell cycle progression of three different ascites tumor cell lines in vivo (Ehrlich, Crocker S 180, and leukemia L 1210) were studied in detail by flow microfluorometric techniques over a 5-day period of drug treatment and during the post-treatment course. These investigations give evidence that the tumor lines employed show completely different sensitivity against VCR and VLB. During the treatment massive polyploidization was demonstrated to be, in general, the second response of treated cells overcoming an initial proliferative block in the G 2 phase of their life cycle.

Animals↗
PubMed1978

On the existence of 'arrested G2 cells' in mouse epidermis.

It has been postulated that mouse epidermis contains two populations of resting cells, one of which is blocked at the G1-S boundary and the other between G2 and mitosis. The 'arrested G2 cells' were estimated, by the labelled mitosis method, to comprise 5-10% of the epidermal population and presumed to function as a 'reserve pool' which could be activated by wounding. A comprehensive search has now been carried out for arrested G2 cells in mouse epidermis using the direct methods of single cell and flow through cytophotometry. No evidence was obtained which supports the existence of such a cell compartment. Suitable control experiments were carried out to ensure that G2 cells were not lost during the isolation of epidermal nuclei.

Aging↗
PubMed1977

[Electromyographic rest-activity. Unusual forms of spontaneous discharge in healthy and sick skeletal muscle].

The forms of spontaneous activity termed as "benign fibrillation potentials" and "benign positive sharp waves" differ from the denervation potentials of the same wave form in the discharge pattern. Fibrillation potentials and positive sharp waves due to a denervation process show a characteristic rhythmical discharge sequence. "Benign fibrillation potentials" and "benign positive sharp waves", on the other hand, display a big difference in the duration of the time intervals between successive waves. It is important to be aware of the frequent occurrence of these benign fibrillations in normal muscles, in order to avoid erroneously diagnosing a denervation process. As in the case of malign fasciculations, "proximal fasciculations" generally occur in lesions of the proximal segment of the lower motoneuron, and have the same diagnostic significance. Unlike malign fasciculations, however, they do not originate in the region of the terminal nerve branches, but at the site of the lesion in question. Local reduction in the stimulus threshold and in the accommodation ensure that a spontaneous impulse will occur. "Low frequency bizarre discharges" and "periods of grouped and serial-discharges" occur mainly in the late phase of a neuromuscular disease and are found especially after traumatic lesions or lesions due to entrapment. We are able to demonstrate that the "low-frequency bizarre discharges" are of myogenic origin, whereas the "periods of grouped and serial-discharges" more than likely originate in the course of the peripheral motoneuron from an active focus.

Action Potentials↗
PubMed1977

[Contribution to facial spasm (author's transl)].

Clinical, electromyographic, neurographic, and nystagmographic results of 20 cases of facial spasm are reported. The syndrome is discussed with reference to parabiosis of the facial nerve and the "ephapse" theory, the localization of facial nerve lesions, and possible etiologic factors of parabiotic changes. For the pathogenesis chronic and subclinical preimpairments of facial nerve axons are postulated as causing, after subsequent additional affections, an "ephaptic" transfer to neighboring fibers. Therapeutic possibilities are discussed.

Adult↗
PubMed1977

Flow microfluorometric monitoring of the interaction of lipid vesicles with cells.

Flow microfluorometric techniques have been applied to experiments concerned with the penetration of cells by lipid vesicles. The high sensitivity of laser flow systems enables to measure the weak fluorescence emitted by individiual liposomes tagged with perylene, inserted into their multilamellar layer. The total fluorescence of cells which habe incorporated such perylene-loaded liposomes could be measured and well separated from that unbound liposomes. Significant differences in the incorporation rates of cationic and anionic liposomes were shown by means of time-course analyses of cellular fluorescence spectra. The advantages of the rapid data analysis by flow fluorescence techniques is discussed in comparison with conventional radio-isotopic methods.

Computers↗