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PubMed1992

[Valve movement of the mussel Dreissena polymorpha as a monitoring system for bodies of water].

A new biological "early warning system" for continuous water control is presented that is based on the valve movements of the freshwater mussel Dreissena polymorpha. For two groups of up to 42 mussels, both the percentage of open mussels and the number of valve movements during a time interval are used to describe the activity behaviour of the zebra mussel. A main prerequisite of such a biomonitor should be the knowledge of the "normal" behaviour in correlation to changing environmental conditions. Preliminary results in Dreissena demonstrate the influence of the temperature, the daily cycle of light and the food concentration on both characteristics of the activity pattern. During toxicity tests, the mussels reacted significantly within 3-30 minutes after the addition of a toxicant. This was normally observed by both the decrease of the percentage of open mussels and the increase of the number of valve movements. Therefore--and against the background of the well-known "normal" behaviour--reliable limits for the detection of a harassing event can be defined. First experiments with Pentachlorophenol, Lindane, Atrazine and 2-Nitrophenol demonstrated to some extent a higher sensitivity compared to other "early warning systems".

Animals↗
PubMed1992

Computerized plotting of low skin impedance points.

The distribution of low skin impedance points (LSIP) was studied on 68 subjects with a computer system designed for the measurement of skin impedance. The results demonstrated that LSIPs were basically distributed along the 14 channels, the overwhelming majority located right on or within 5 mm bilaterally to their courses. LSIPs were found in the area between every two channels only in a few cases. Moreover, there was no marked natural fluctuation of skin impedance in the human body and the distribution of LSIPs was considerably stable, which could be plotted on any day in the experiment. It is clear that such particular distribution of LSIPs along channels was really a biological phenomenon, not an experimental error. However, the distribution of low skin impedance was not an uninterrupted solid line but a series of LSIPs basically along the channel course. The method used in this work was accurate, reliable and repeatable which has upgraded the measurement of LSIPs to a new level. Under certain conditions, skin impedance can be used as an objective index in channel research.

Adult↗
PubMedDate not supplied

[Application of physiological data in evaluation of the intracranial volume-pressure interaction. I. An experimental study].

In experimental studies on cats the pressure and volume loadings corresponding to the physiological situations were used. The following tests were applied: central venous pressure increase, postural changes and increase of CO2 percentage in inspired gas mixture. It was found that the central venous pressure increase test is useful in the evaluation of CSF outflow routes, the postural change test examines the intracranial compensation and the elevation of CO2 level in inspired air tests the intracranial volume reserve.

Animals↗
PubMedDate not supplied

[An electrophysiological analysis of brain maturation in chicken embryogenesis].

Studies have been made on the development of the spontaneous bioelectrical activity in the brain of 13-21-day chick embryos and on the reactions of the brain to sonic and photic stimulation (single and rhythmic). It was shown that the onset of the evoked responses to afferent stimulation coincides with predominance of a periodic process in the bioelectrical activity (17-18th days of embryogenesis). The presence of ordered rhythmicity in the bioelectrical activity of the brain which coincides with a possibility of its transformation and synchronization with afferent stimuli is suggested to be an important index of the development of the brain.

Acoustic Stimulation↗
PubMed2026

An automated geometric modeling framework in GATE for the design and optimization of high-sensitivity converging-beam SPECT collimators.

Objective.The trade-off between detection sensitivity and spatial resolution is a fundamental challenge in designing organ-dedicated Single-photon emission computed tomography (SPECT) collimators. While converging-hole geometries offer a solution, their optimization is often hindered by the lack of flexible computational tools capable of modeling large-scale, non-parallel hole arrays. This study aims to develop an automated geometric modeling framework to facilitate the design and evaluation of complex converging- and diverging-hole collimators within standard Monte Carlo environments.Approach.We developed a specialized modeling framework by implementing custom C++ classes and a vector-based alignment algorithm within GATE. This platform enables automated, orientation-consistent construction of large-scale converging arrays not natively supported by standard implementations. A high-sensitivity pure cone-beam collimator (CBC) was designed using this framework. The evaluation used hot-rod, disc, and Jaszczak phantoms for physical characterization, while XCAT and dedicated brain models were employed for clinical tasks, including cardiac, brain perfusion, and DaTscan SPECT simulations.Main results.The CBC achieved a nearly fourfold sensitivity increase compared to a conventional low-energy high-resolution parallel-hole collimator at a 20 cm radius of rotation, while maintaining comparable spatial resolution. Despite a 52.3% field of view reduction, the CBC yielded a 2.2-fold noise reduction (CV: 11.7% vs 25.9%) and mitigated partial volume effects via geometric magnification. XCAT and brain phantom simulations confirmed enhanced anatomical definition and contrast recovery in cardiac, perfusion, and DaTscan tasks.Significance.This work provides an efficient computational tool for rapid design space exploration of advanced collimator geometries. The results demonstrate that the proposed CBC design offers a significant sensitivity advantage, making it highly suitable for high-performance, small-volume clinical applications such as brain and cardiac molecular imaging.

Tomography, Emission-Computed, Single-Photon↗
PubMedDate not supplied

Localization of a sequence motif complementary to the nuclear localization signal in proteasomes from Thermoplasma acidophilum by immunoelectron microscopy.

A sequence motif complementary to the nuclear localization signal (NLS) has been localized in proteasomes from Thermoplasma acidophilum by immunoelectron microscopy using sequence-specific antibodies. The antibodies were generated in two different ways: by immunization with a carrier-coupled peptide and by isolation of the sequence-specific antibody from an immune serum against native proteasomes using a peptide-affinity column. The sequence specificity of the isolated antibody was confirmed by a PEPSCAN-ELISA performed on overlapping nonapeptides deduced from the sequence of the alpha-subunit of the Thermoplasma proteasome. Compared to the antibody induced by the carrier-coupled peptide this antibody fraction showed a much higher affinity for native proteasomes. The attachment site of the Fab portion of the antibody to the proteasome was mapped by electron microscopy in conjunction with image processing. The antibody was found to bind to the periphery of the two outer "disks" of the proteasome complex formed by the alpha-subunits.

Amino Acid Sequence↗
PubMed1976

Suggested minimum performance characteristics of data acquisition instrumentation in computer-assisted ECG processing systems.

The increasing importance of electrocardiogram (ECG) interpretation by computers warrants consideration of the specific technical requirements for ECG recorders used in computer-assisted ECG interpretation systems. An almost uniform characteristic of these devices is their capability to transmit the ECG signal over common carrier lines. This paper suggests minimum performance characteristics for the different components of a teletransmitting ECG recorder to facilitate the use and evaluation of computer-assisted interpretation systems. Considered are the need for signal fidelity, features for automatic quality control, and features for patient and technician safety. The performance characteristics for the ECG amplifier are only stated where they exceed the most recent recommendations of the Committee on Electrocardiography, American Heart Association. The features of the teletransmission section are based on a widely used mode and format of transmission.

Amplifiers, Electronic↗
PubMedDate not supplied

Atrial electrogram monitoring in a cardiac care unit.

Routine monitoring of a bipolar atrial electrogram (AEG) simultaneously with the electrocardiogram is a useful and safe clinical technique for the diagnosis of complex cardiac dysrhythmias. The large-amplitude A waves of the AEG can be more reliably identified than the corresponding low-amplitude p waves of the electrocardiogram. Epicardial wires placed during cardiac surgery, catheter-mounted endocardial electrodes, and esophageal electrodes can all be used for routine AEG monitoring. A multipurpose pulmonary arterial catheter with a pair of electrodes, and esophageal electrodes can all be used for routine AEG monitoring. A multipurpose pulmonary arterial catheter with a pair of electrodes mounted on the proximal shaft can be used for combined AEG and hemodynamic monitoring. The equipment needed for AEG monitoring and recording consists of an additional bedside amplifier with 12- to 100-Hz band-pass filter, a dual-channel display scope, and a dual-channel strip chart recorder. Care must be used to keep the atrial electrodes electrically isolated for patient safety. In addition to enhancing the diagnosis and management of dysrhythmias, recording an AEG provides a signal that is suitable for automatic processing.

Arrhythmias, Cardiac↗
PubMed2021

Epigenetically regulated digital signaling defines epithelial innate immunity at the tissue level.

To prevent damage to the host or its commensal microbiota, epithelial tissues must match the intensity of the immune response to the severity of a biological threat. Toll-like receptors allow epithelial cells to identify microbe associated molecular patterns. However, the mechanisms that mitigate biological noise in single cells to ensure quantitatively appropriate responses remain unclear. Here we address this question using single cell and single molecule approaches in mammary epithelial cells and primary organoids. We find that epithelial tissues respond to bacterial microbe associated molecular patterns by activating a subset of cells in an all-or-nothing (i.e. digital) manner. The maximum fraction of responsive cells is regulated by a bimodal epigenetic switch that licenses the TLR2 promoter for transcription across multiple generations. This mechanism confers a flexible memory of inflammatory events as well as unique spatio-temporal control of epithelial tissue-level immune responses. We propose that epigenetic licensing in individual cells allows for long-term, quantitative fine-tuning of population-level responses.

Animals↗
PubMed1976

International standard (C.C.I.T.T.) for transmitting biomedical analogue and digital data on the public telephone network.

Analogue transmission of biomedical signals over the public telephone network has advantages from the economic point of view over digitalized transmission. This paper deals with the special problems encountered with the transmission of biomedical signals. Furthermore, the new international transmission standard C.C.I.T.T. recommendation V. 16 is introduced. This standard has recently been adopted by the relevant study group and has been presented to the Plenary Assembly of the C.C.I.T.T. for final approval. This standard is compatible with the existing public telephone networks. The technical specifications of this standard allow the transmission of the three-channel ECG for diagnostic purposes, e.g., remote processing and computer-assisted evaluation, as well as the transmission of the one-channel ECG with acoustic coupling, e.g., in emergency cases and for pace maker monitoring.

Analog-Digital Conversion↗
PubMed2026

Striping artifact removal in VisiumHD data through nuclear counts modeling.

MOTIVATION: 10x Genomics VisiumHD enables spatial transcriptomics at 2 µm × 2 µm resolution but exhibits slide-specific, non-periodic striping artifacts due to lane-width variability. These multiplicative row/column effects distort bin total counts and can bias downstream analyses. The state-of-the-art destriping approach is the normalization procedure used as a preprocessing step in bin2cell; it applies sequential high-quantile row- then column-wise normalization, which is asymmetric and can introduce edge effects/macro-stripes and distortions of large-scale total-count structure. RESULTS: We propose a statistical destriping approach that leverages nuclei segmentation from the co-registered H&E image. Assuming transcript abundance is constant within each nucleus, we model bin counts with a negative binomial distribution whose mean is a product of a nucleus-specific concentration and row- and column-specific stripe-factors reflecting lane-width variation. We fit all parameters in a generalized linear modeling framework with cross-validated regularization on stripe-factors and iterative dispersion estimation, and use the fitted parameters to correct the observed counts into a destriped image. On synthetic data with known ground truth, our method improves stripe-factor estimation accuracy and reduces error in corrected counts relative to bin2cell and bin2cell-derived baselines. Across four public VisiumHD slides, it consistently lowers striping intensity while substantially better preserving biological signal present in the large-scale global count structure and avoiding the artifacts introduced by other methods. AVAILABILITY AND IMPLEMENTATION: All source code and links to publicly available data used for this study are available at https://github.com/paolamalsot/destriping-GLM.

Artifacts↗
PubMed1977

[Universal measurement site for the processing-oriented recording of cardiovascular data].

A measuring place is described for the registration of standardized, evaluable by means of the computer deviations of bioelectric signals (parameters of heart and circulation, peripheral pulse curves and rheogramms). The high demands which concern the adequate establishment measuring places with regard to quality and comfort of attendance and condition corresponding technical solutions are explained. At the instance of the rheogram the mode of function is described. A short prognosis on the trend of development in the recognition of biological measuring values is given.

Cardiovascular Diseases↗
PubMedDate not supplied

Noninvasive external recording of cardiac conduction system (His bundle) activity.

Successful and adequate external recording of the cardiac conduction system from the body's surface can be accomplished in 80 to 90 percent of subjects studied. High-gain amplification, signal averaging, and triggering with a conditioned QRS signal results in good recording reproducibility. Averaging of 128 consecutive cycles is adequate, but on occasion averaging of 256 cycles may yield better results. The patients's QRS signal triggers the transfer of signals, which are digitized and stored during the preceding P-R interval. Comparison of external recordings with direct invasive recordings in animals and patients shows good correlation between the major His bundle deflections. The advantages of the system developed include its mobility, triggering the QRS with pretrigger data processing, and instantaneous display on Polaroid photograph. Future research should concentrate on further miniaturization and simplification of the instrumentation, detailed experimental comparison between direct and external recordings for identification of deflections and their origin, further study of the recording lead system, and the most appropriate method of information display.

Animals↗
PubMed1977

The role of the digital computer in pediatric cardiology.

A digital computer system is described which allows the real-time processing of all physiological signals obtained during a heart catheterization procedure and which makes all relevant results and informations available immediately during the investigation. In addition, special electronic units and programs have been developed in our institution for the automated extraction of morphological criteria from biplane angiocardiograms. Thereby right and left ventricular volume, shape and contraction pattern can be quantitated and used to characterize the performance of the heart as muscle and pump in physical terms. Recently, complete digital processing of videoangiocardiograms has been achieved in a stroboscopic mode, each videofield in real time. Application of image enhancement, subtraction, integration and restoration techniques leads to a fundamentally improved angiocardiographic image quality for a given amount of injected contrast material. Based on eight years of experience with digital computer application in pediatric cardiology, computer technologies are considered likely to become the method of choice in the future.

Angiocardiography↗