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Biomedical subjects

A Bischoff

Publications and source records attributed to A Bischoff.

At least 109 records · Page 6Linked to original sources
PubMed1994

Dose-response relationship of rocuronium bromide during intravenous anaesthesia.

The dose-response relationship and time course of neuromuscular block following bolus injections of rocuronium was determined in four groups of nine patients each under nitrous oxide-narcotic anaesthesia. Each patient received a total of 800 micrograms kg-1 rocuronium in two divided doses, i.e. 120 and 680, 200 and 600, 250 and 550, or 300 and 500 micrograms kg-1. The respective second dose was injected when, following the first dose, the evoked twitch tension had recovered to 95% of its control value. The mean ED50 and ED95 values, calculated from the first doses, were 103 and 271 micrograms kg-1, respectively. The DUR25 ranged between 11 +/- 4 (200 micrograms kg-1) to 14 +/- 3 min (300 micrograms kg-1) following the first and from 30 +/- 6 (500 micrograms kg-1) to 43 +/- 11 min (680 micrograms kg-1) following the second doses. The recovery index following the second doses varied between 14 +/- 5 (500 micrograms kg-1) and 24 +/- 20 min (600 micrograms kg-1), more than twice as long as following the first doses. We conclude that rocuronium is a muscle relaxant of low potency with an intermediate duration of action.

Adult↗
PubMed1993

Differences of size and shape of active and inactive X-chromosome domains in human amniotic fluid cell nuclei.

It is a widely held belief that the inactive X-chromosome (Xi) in female cell nuclei is strongly condensed as compared to the largely decondensed active X-chromosome (Xa). We have reconsidered this problem and painted X-chromosome domains in nuclei of subconfluent, female and male human amniotic fluid cell cultures (46,XX and 46,XY) by chromosomal in situ suppression (CISS) hybridization with biotinylated human X-chromosome specific library DNA. FITC-conjugated avidin was used for probe detection and nuclei were counterstained with propidium iodide (PI). The shape of these nuclei resembling flat ellipsoids or elliptical cylinders makes them suitable for both two-dimensional (2D) and three-dimensional (3D) analyses. 2D analyses of Xi- and Xa-domains were performed in 34 female cell nuclei by outlining of the painted domains using a camera lucida. Identification of the sex chromatin body in DAPI-stained nuclei prior to CISS-hybridization was confirmed by its colocalization with one of the two painted X-domains. In 31 of the 34 nuclei the area AXi for the inactive X-domain was smaller than the area AXa for the active domain (mean ratio AXa/AXi = 1.9 +/- 0.8 SD, range 1.0-4.3). The signed rank test showed a highly significant (P < .0001) difference both between AXa and AXi and between the ratios r(Xa) and r(Xi), calculated by dividing the maximum length L of each X-domain by its maximum width W. In most nuclei (26/34) we found r(Xa) > r(Xi) demonstrating a generally more elongated structure of Xa. For 3D analysis a confocal scanning laser fluorescence microscope (CSLFM) was used. Ten to 20 light optical sections (PI-image, FITC-image) were registered with equal spacings (approx. 0.4 microns). A thresholding procedure was applied to determine the PI-labeled nuclear and FITC-labeled X-domain areas in each section. Estimated slice volumes were used to compute total nuclear and X-domain volumes. In a series of 35 female nuclei most domains extended from the top to the bottom nuclear sections. The larger of the two X-chromosome domains comprised (3.7 +/- 1.7 S.D.)% of the nuclear volume. A mean ratio of 1.2 +/- 0.2 SD (range 1.1-2.3) was found for the volumes of the larger and the smaller X-domains in these female nuclei. In a series of 27 male amniotic fluid cell nuclei the relative X-chromosome domain volume comprised (4.0 +/- 2.6 S.D.)%.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniotic Fluid↗
PubMed1992

Automated detection of radiation-induced chromosome aberrations following fluorescence in situ hybridization.

The cytogenetic detection of rare chromosome aberrations induced by ionizing radiation requires the evaluation of large numbers of cells. In this report, an image analysis program based on thresholding of grey level histograms is described for a rapid automated detection of chromosome translocations in metaphase spreads from human lymphocytes following irradiation and chromosome in situ suppression (CISS) fluorescence in situ hybridization (FISH). To classify a metaphase spread as "normal", "aberrant", or "excluded", a minimum medium time of less than two seconds was required on a general purpose Personal Computer. Using appropriately stained specimen, for the false classification rate an upper limit of about 10% was estimated. The upper limit for the rate of "excluded" cells was estimated to be about 11% (99% confidence ranges). FISH-procedures allow to score chromosome aberrations also in the interphase nucleus. To apply simple threshold algorithms for segmentation of the FISH-stained nuclear areas, it is required that the grey level contrast is sufficiently high. The preliminary results presented here on the image analysis of human lymphocyte nuclei suggest the feasibility of such an approach.

Chromosomes↗
PubMed1991

Response of the medullary respiratory network of the cat to hypoxia.

1. The effect of systemic hypoxia was tested in anaesthetized, immobilized, thoracotomized and artificially ventilated cats with peripheral chemoreceptor afferents either intact or cut. Extracellular recordings from different types of medullary respiratory neurones and intracellular recordings from stage 2 expiratory neurones were made to determine the hypoxia-induced changes in neuronal discharge patterns and postsynaptic activity as an index for the disturbances of synaptic interaction within the network. 2. The general effect of systemic hypoxia was an initial augmentation of respiratory activity followed by a secondary depression. In chemoreceptor-denervated animals, secondary depression led to central apnoea. 3. The effects of systemic hypoxia were comparable with those of cerebral ischaemia following occlusion of carotid and vertebral arteries. 4. In chemoreceptor-denervated animals, all types of medullary respiratory neurones ceased spontaneous action potential discharge during hypoxia. 5. Reversal of inhibitory postsynaptic potentials (IPSPs) and/or blockade of IPSPs was seen after 2-3 min of hypoxia. 6. During hypoxia, the membrane potential of stage 2 expiratory neurones showed a slight depolarization to -45 to -55 mV and then remained stable. 7. The neurone input resistance increased initially and then decreased significantly during central apnoea. 8. Rhythmogenesis of respiration was greatly disturbed. This was due to blockade of IPSPs and, in some animals, to more complex disturbances of phase switching from inspiration to expiration. 9. Central apnoea occurred while respiratory neurones were still excitable as shown by stimulus-evoked orthodromic and antidromic action potentials. 10. The results indicate that the medullary respiratory network is directly affected by energy depletion. There is indication for a neurohumoral mechanism which blocks synaptic interaction between respiratory neurones in chemoreceptor-intact animals.

Action Potentials↗
PubMed1991

Respiratory neuronal activity during apnea and other breathing patterns induced by laryngeal stimulation.

Respiration cycles through three distinct phases (inspiration, postinspiration, and expiration) each having corresponding medullary cells that are excited during one phase and inhibited during the other two. Laryngeal stimulation is known to induce apnea in newborn animals, but the cellular mechanisms underlying this effect are not known. Intracellular recording of ventral respiratory group neurons was accomplished in intact anesthetized, paralyzed, and mechanically ventilated piglets. Apnea was induced by insufflation of the larynx with ammonia-saturated air, smoke, or water. Laryngeal insufflation induced phrenic nerve apnea, stimulation of postinspiratory neurons, and stable membrane potentials in inspiratory and expiratory cells consistent with postinspiratory inhibition. Usually the membrane potential of each neuronal type cycled through an expiratory level before onset of the first recovery breath. Variants of the apnea response, probably reflecting the aspiration reflex or sniffing, sneezing, coughing, and swallowing, were also observed. These latter patterns showed oscillation between inspiration and postinspiration without an apparent intervening stage II expiratory phase. However, stage II expiratory activity always preceded onset of the first ramp inspiration after such a pattern. These findings suggest that activation of postinspiratory mechanisms causes profound alterations in the respiratory pattern and that stage II expiration importantly modulates recovery of ramp inspiratory activity. The mechanism of this latter effect may be inhibition of early inspiratory neurons with consequent postinhibitory rebound.

Animals↗
PubMed1991

[Outpatient dental surgery under anesthesiological monitoring. Investigation with 1022 patients at risk].

The aim of the study was to explore retrospectively the risks of ambulatory treatment under local anaesthesia during dental operations of elderly patients. Anaesthetic care was divided into control and therapeutical measures. Among the previous disorders the hypertension and its sequelae proved to be the main risk factors. The need of anaesthetic intervention doubled, when the time of operation exceeded 30 min. Due to good interdisciplinary cooperation, 99.3% of the operations took their proper course.

Adolescent↗
PubMed1989

Intracellular recordings of respiratory neurons in the lateral medulla of piglets.

Membrane potentials of respiratory neurons in the ventral respiratory group were recorded using intracellular techniques in the medulla of newborn piglets. Three types of neurons were demonstrated: inspiratory neurons with an augmenting pattern of spike activity during inspiration; postinspiratory neurons with a short decrementing firing pattern that started immediately after inspiration ended; and stage II expiratory neurons with an augmenting spiking pattern that began shortly after inspiratory termination and ended before onset of the next inspiration. When not firing, the membrane potential trajectories of each cell type revealed two complementary patterns of relative inhibition. This latter finding suggests arrival of inhibitory synaptic potentials during these periods. These findings suggest that the respiratory control mechanisms of the newborn piglet are organized in a three-phased manner similar to that of adult cats.

Action Potentials↗
PubMed1988

Effect of propranolol on early postischemia arrhythmias and noradrenaline and potassium release of ischemic myocardium in anesthetized pigs.

In anesthetized open-chest pigs, DL- or D-propranolol (1 mg/kg i.v.) was administered 15 min prior to ligation of the left anterior descending coronary artery (LAD) about halfway from its origin. Sequential myocardial tissue samples were obtained before and after LAD occlusion. The samples were analyzed histofluorimetrically to determine the density of catecholamine containing neurons (quantified morphometrically), and radioenzymatically for total tissue noradrenaline content. The extracellular K+ concentration was measured using K+-sensitive polyvinyl chloride (PVC)-membrane electrodes on the surface of the ischemic myocardium. Under control conditions, ventricular arrhythmias (VA) occurred in a typical 1a and 1b phase. Pretreatment with propranolol diminished the number of VA generated in the 1b phase but not those in the 1a phase; however, these differences were statistically not significant. Neither pretreatment with DL- nor D-propranolol influenced the time course or probability of development of ventricular fibrillation (VF). Coronary artery occlusion led to a significant reduction in noradrenaline concentration of the ischemic myocardium in control animals (from an initial concentration of 526 +/- 65 ng/g w/w to 368 +/- 75 ng/g w/w) within the first 5 min of ischemia, whereas noradrenaline concentration remained nearly unchanged in drug-treated animals (from 838 +/- 86 to 811 +/- 61 ng/g w/w in the DL group and from 701 +/- 36 to 709 +/- 31 ng/g w/w in animals that received D-propranolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1987

[Metoclopramide, methylprednisolone and flunitrazepam in cytostatic-induced vomiting].

The antiemetic efficacy of a combination of high-dose metoclopramide, methylprednisolone and flunitrazepam was tested in an open pilot study in 30 tumor patients undergoing strongly emetic chemotherapy. 26 of 30 patients (87%) were partially or completely protected from nausea and vomiting. In 11 of 12 patients receiving the strongly emetogenic cytostatic agent cisplatin in a dose of greater than or equal to 50 mg/m2, the gastrointestinal side effects were partially or completely abolished. The antiemetic efficacy of the combination was maintained during subsequent courses of chemotherapy. All patients experienced somnolence after administration of flunitrazepam. Only 2 of 30 patients had a shortlived extrapyramidal reaction. The combination of high-dose metoclopramide, methylprednisolone and flunitrazepam is an effective antiemetic treatment and should be considered as first-line antiemetic treatment in patients receiving strongly emetic cancer chemotherapy.

Adolescent↗
PubMed1982

Levonantradol, a new antiemetic with a high rate of side-effects for the prevention of nausea and vomiting in patients receiving cancer chemotherapy.

Levonantradol, a new antiemetic compound pharmacologically related to the cannabinoids, was given to 17 patients who had experienced severe and protracted nausea and vomiting during previous courses of cancer chemotherapy, and to six patients receiving a first course of strongly emetic cytostatic treatment. Eight patients were partially protected from acute gastrointestinal disturbances. Of the 23 patients, 21 exhibited some toxicity, with six patients exhibiting major affective side-effects and 13 patients complaining of pain at the injection site. Levonantradol is an active antiemetic compound. Due to the rate of side-effects observed in our study however, we would not recommend use of this agent as an antiemetic drug.

Adult↗
PubMed1981

Sensory ganglioneuropathy in infantile spinal muscular atrophy. Light and electronmicroscopic findings in two cases.

Light and electronmicroscopic findings in two cases. Neuropediatrics 12: 215-31 (1981). Two cases of infantile spinal muscular atrophy (Werdnig-Hoffmann disease) are described in unrelated children deceased at 11 months (acute clinical onset at 6 months) and 2 years (onset at birth). Severe respiratory difficulties, hypotonia, muscular weakness and depressed tendon reflexes were the main clinical features. Bulbar palsy, bilateral ptosis, pale optic discs and atactic movements of the hands were observed in the child deceased at 11 months. Besides severe loss of anterior horn cells and neurogenic muscle atrophy there was evidence of an extensive sensory involvement in both cases. Shrinkage, vacuolation as well as chromatolytic changes of dorsal root ganglion cells, together with the evidence of a primary axonal damage in sural nerve biopsies were interpreted in terms of ganglioneuropathy of the primary sensory neurons. An invasion of fibrous astrocytes into dorsal roots constituted another striking anomaly in one case as well as a pronounced degeneration of cranial nerves V and VIII in the other case, a finding not hitherto reported in Werdnig-Hoffmann disease.

Brain↗
PubMed1980

The natural course of diabetic neuropathy. A follow-up.

Out of an unselected group of 160 patients with diabetic neuropathy 51 patients were followed up for an average of 5, 6 years by repeated neurological examinations and by means of a questionnaire. The control of the diabetes was requested from the house physicians. The patients were classified as presenting (1) a symmetrical, predominantly sensory neuropathy (2) a mixed syndrome with additional autonomic neuropathy and (3) multiple mononeuropathy. Individual symptoms and objective signs of neuropathy revealed a remarkable variety of changes. The outlook in multiple mononeuropathy and distal paresis was favorable while autonomic failures, in particular of male sexual function, progressed. There seemed to be some beneficial effect of improved glycemic control. However, despite satisfactory metabolic control some progression of diabetic neuropathy occured.

Diabetic Neuropathies↗