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Biomedical subjects

M Bach

Publications and source records attributed to M Bach.

At least 163 records · Page 9Linked to original sources
PubMed1986

A multiple sample immunoblotting system (MSIS) for the intrinsic detection of antinuclear autoantibodies.

A multiple sample immunoblotting system (MSIS) is described. The MSIS permits the detection and classification of antinuclear antibodies (ANA) according to the pattern of antigenic polypeptides recognized in four different extracts: calf thymus whole tissue, nuclear extract, and two ammonium sulphate fractions of the nuclear extract. The procedure permits the classification of anti-RNP, anti-SS/B and anti-Sm, and the detection of new ANAs in sera from SLE patients. The reaction patterns presented are specific and unambiguous, and make the use of validated control sera unnecessary.

Antibodies, Antinuclear↗
PubMed1986

Correlated neuronal variability in monkey visual cortex revealed by a multi-microelectrode.

Recordings from the visual cortex of anaesthetized monkeys taken with a 30-fold multi-microelectrode demonstrate that the neuronal variability, defined as the change in response strength over time spans of a few seconds to several minutes, is highly correlated within groups of neurones. Several such groups exhibiting independent variability between groups, coexist within the area recorded. This within-group covariance suggests that a major part of neuronal variability is due not to a noise process in the cells, but rather to additional inputs to the neurones, which are not under control of the experimenter.

Animals↗
PubMed1985

The C-wave in hereditary degenerations of the ocular fundus.

The c-wave of the human direct current ERG may give new insights about the involvement of the retinal pigment epithelium in hereditary degenerations. In our single-sweep recordings from 236 alert patients we saw reduced c-waves not only in vitelliforme macular degenerations but also in dominantly inherited drusen, Stargardt's disease, cone dystrophies, and x-linked retinoschisis. In achromatopsia the c-wave was close to normal. The relationship of the b- and c-wave, however, was altered only in Best's disease, cone dystrophy, and x-linked retinoschisis. We postulate that the c-wave when more severely reduced than the b-wave reflects not merely the dysfunction of the pigment epithelium but more precisely whether this retinal layer is involved earlier than the photoreceptors.

Electroretinography↗
PubMed1985

Visual evoked potentials to various check patterns.

A target screen stimulus takes into account the necessity of larger checkerboard patterns with rising eccentricity. The target pattern should be calculated to fit the retinocortical magnification factor. This proposition is based on the working hypothesis that for maximal visual evoked potential (VEP) amplitude the stimulus should appear on the cortex as an undistorted checkerboard pattern. We describe the cortical response elicited by four different target screen stimuli based on a similar algorithm. No significant difference to normal checkerboard was found.

Cerebral Cortex↗
PubMed1984

A versatile simulator of evoked potentials.

A simple electronic device is described which simulates evoked potentials with variable amounts of superimposed noise to facilitate routine checking and testing of apparatus and computer programs in an evoked potential laboratory.

Computers↗
PubMed1984

Characterization of antigenic polypeptides of the RNP, Sm and SS-B nuclear antigens from calf thymus.

Antinuclear autoantibodies are a hallmark of autoimmune diseases. The RNP, Sm and SS-B nuclear antigens from calf thymus in whole tissue, nuclear extracts and fractions have been studied by using different techniques including immunodiffusion, counterimmunoelectrophoresis and protein blotting. Such studies were done in order to obtain a precise characterization of the polypeptide components of those antigens. From our results it can be established that: one 69.8 Kd polypeptide (for whole tissue and nuclei) and a number of well-defined 32-38-Kd polypeptides (for nuclear extracts and ammonium sulfate fractions) show an antigenic character against anti-RNP sera; anti-Sm sera from different patients show in all cases a variable component of antigenic polypeptides, including one 28.8, 29.7 Kd doublet and two singlets of 14.8 and 11.0 Kd; and a 52.0-Kd SS-B antigenic polypeptide is found for whole tissue, which is gradually degraded in nuclei and nuclear extracts to a more stable 47.1-Kd polypeptide.

Animals↗
PubMed1983

An accurate and linear infrared oculometer.

A method for measuring horizontal and vertical eye movements is described. The oculometer utilize infrared light and resolves 0.1 degree over a linear range of +/- 20 degrees. The simultaneous observation of the fixation target and eye position with an infrared mirror and two television cameras on a single monitor makes the mechanical and electrical calibration very easy. The system has been used successfully in animal studies of vision and eye movements, in particular during recording of single cells in visual brain structures of behaving monkeys.

Animals↗
PubMed1982

Independent systems of orientation columns in upper and lower layers of monkey visual cortex.

Using a multi-microelectrode, in 5 animals, orientation tuning was measured simultaneously in 30 closely spaced parallel penetrations perpendicular to the surface of the striate cortex. Actual penetration angles were determined by three-dimensional track reconstruction. Above and below layer IVc, two columnar systems were found whose orientation angles were independent.

Animals↗
PubMed1981

Simultaneous recording with 30 microelectrodes in monkey visual cortex.

A 30-fold multielectrode for extracellular recording of neuronal spikes is described. Single neuronal spikes were isolated simultaneously by about half of the electrodes. The technique has been applied to demonstrate the spatial distribution of ocular dominance and orientation preference in striate cortex.

Animals↗
PubMed1981

Stimulus versus eye movements: comparison of neural activity in the striate and prelunate visual cortex (A17 and A19) of trained rhesus monkey.

Visual responses were recorded from single cells in the parafoveal striate (A17) and prelunate (A19) cortex of awake rhesus monkeys while they were fixating a stationary or moving spot of light in the presence of a moving or stationary stimulus. Retinotopy and stimulus requirements were found to be less strict in A19 as compared to A17. Striate cells preferred slow stimulus movements and displayed a large amount of binocular interaction. Many prelunate cells responded well to fast stimulus movements, all were binocular but only a few showed binocular interaction. In both areas an overall deficit of visual responses during saccadic eye movements was observed which was mostly due to the cells' inability to respond to stimuli moving at saccadic velocities. Only in A19 were there cells which seemed to receive non-sensory signals reducing visual responses during rapid eye movements. We concluded that the prelunate cortex has access to input which does not use the geniculate-striate pathway. The additional observation of presaccadic activation of some cells supports the idea that activity in the prelunate cortex may be associated with events related to visually guided changes of the direction of gaze and/or attention.

Animals↗