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Biomedical subjects

M Stöhr

Publications and source records attributed to M Stöhr.

At least 91 records · Page 5Linked to original sources
PubMed1981

Responses of synchronized HeLa cells to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate as evaluated by flow cytometry.

A flow cytometric study was carried out on the effects of tumor-promoting 12-O-tetradecanoylphorbol-13-acetate (TPA; 10(-8) M) on HeLa cells synchronized by amethopterin for DNA synthesis. Cells treated with TPA at the time of release from the amethopterin block showed a delayed passage through S phase and partially through G2 in their immediate life span as measured 24 hr after release. This late G2 delay was not observed when TPA was added to cells during late S or G2 phase. In this case, however, a direct inhibition of cells in G2 became evident as observed about 15 hr after release from block. None of these effects was caused by the nonpromoting 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate (10(-6) M). These data support observations obtained with asynchronous cultures. The TPA effects resemble those reported after X-irradiation of cell cultures.

Cell Cycle↗
PubMed1980

A flow cytometric study of chromosomes from rat kangaroo and Chinese hamster cells.

Chromosomes from rat kangaroo (PTK) and chinese hamster (CHV 79) cells have been prepared for quantitative flow-cytometric analysis. The preparation time was otimized down to 30 (PTK) and 40 min (CHV 79). DAPI was used as a AT-sensitive fluorescent dye to stain for monoparameter DNA measurements. Simultaneous two-parameter DNA-protein analysis was carried out with DAPI and SR 101 (as a general protein fluorochrome) in combination. The karyotype of the PTK cells with 13 (14) chromosomes was separated into 10DNA peaks. The X-chromosome bearing the nucleolus organizer region generates a distinct peak. The karyotype of the CHV 79 cells with 22 chromosomes was separated inot 15 peaks. The DNA profile obtained indicates a geometric grading of the chromosomal amount of AT components in teh karyotype of this particular cell line. The simultaneous DNA-protein analysis performed show enough sensitivity of the instrument utilizing hihg power UV excitation illumination to discriminate the two color emission consisting of blue (DAPI) and red (SR 101) fluorescence. Color overlapping could be completely avoided. Additionally, the quality (number, location, and resolution of peaks) of the DNA distribution was not influences by the simultaneous application of a second fluorescent stain. Fluorescence activated electronic sorting applied on chromosomal fluorescence distributions providing purified fractions of chromosomes for subsequent biochemical and biological determinations is discussed.

Animals↗
PubMed1980

Gerstmann-Sträussler-Scheinker's disease. Electron-microscopic observations on a brain biopsy.

Light and electron microscopic observations are reported on a brain biopsy of a man of 59 with a rare familial disease of the CNS and a 5-year clinical course. Electron micrographs of the frontal biopsy reveal plaque-like deposits composed of amyloid cores, often multicentric in the cortex and subcortical white matter. They are localized between enlarged astrocytic processes. In the neuropil they are sometimes associated with abnormal neuritic processes, in the white matter with processes of fibrous astroglia and basement membranes. There are no signs of primary neuritic or synaptic involvement in the plaque formation which is more obviously associated with altered astrocytic processes. Moreover, degenerative alterations in the cortical vessels and slight astroglial spongiform changes as well as oligodendroglial proliferation can be found. Plaques are considered to be mainly of the kuru type; the relationship with transmissible spongiform encephalopathies is discussed.

Astrocytes↗
PubMed1980

Tumor promoter TPA mimics irradiation effects on the cell cycle of HeLa cells.

When asynchronous and synchronous HeLa cells were incubated with small doses (10(-7) M) of tumor promoter 12 O-tetradecanoylphorbol-13-acetate (TPA), a variety of transient alterations in the replication cycle were detected within 24 hours by the use of independent methods. Especially, a delayed passage through the S phase and influences on the G2 phase resemble x-ray irradiation effects on cell cultures. None of these alterations was observed with the hyperplasiogenic but nonpromoting 4-O-methyl-TPA.

Cell Cycle↗
PubMed1980

Ischaemic neuropathy of the lumbosacral plexus following intragluteal injection.

A lesion of the lumbo sacral plexus may result from an inadvertent intra-arterial injection of vasotoxic drugs into one of the gluteal arteries. Symptoms and follow-up of three cases are reported. The neuropathy is attributed to a toxic endarteritis with retrograde propagation of spasm and thrombosis. Swelling an bluish discoloration of the buttocks ("embolia cutis medicamentosa") as well as an impaired circulation in the homolateral leg are associated with the neurological syndrome in fully developed cases and makes possible a correct diagnosis.

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↗