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PubMedDate not supplied

Non-invasive determination of the distribution of the conduction velocity of the large-diameter fibers in peripheral nerves. Estimate based upon a single recording of the stimulus response of the nerve.

The paper describes a method for the estimation of the frequency of occurrence of fibers with a given conduction velocity among the stronger myelinated fibers of superficial nerves. The method is primarily suited for the examination of sensory nerves. To mixed nerves it can be applied only if interference by excited myopotentials is sufficiently weak. A single averaged recording of the compound action potential of the nerve evoked by a supra-maximal electrical stimulus serves as input. It is shown that integration of that curve with respect to time yields an amplitude weighted graph of the density of fibers with given travel times between the stimulus site and the recording electrode. Unweighting that curve yields the distribution characteristic of the travel delays which can easily be converted to a graph of the conduction velocity density of the fibers in the excited ensemble.

Action Potentials↗
PubMedDate not supplied

[Depression and functional EEG asymmetry].

A new quantified EEG index (Alpha Burst Occurrence Variability Index: alpha BVI) has been devised in order to characterize sequential variations of alpha bursts in EEG. This index makes it possible to quantify slope variations of a cumulative graph (periodogram) where the rank of alpha bursts is traced as a function of their instant of arrival. Such quantitative analysis was applied to spontaneous EEG segments which were recorded in the parieto-occipital regions (P3-Fz and P4-Fz) during a rest period, in three groups of depressed patients, one being characterized by psychomotor retardation (PRM group), another one by an emotional blunting (EB group) and a group of impulsive depressed patients (I group). The patients were compared to a group of healthy control subjects. In the three patient groups, before treatment, it was observed that the right and left alpha BVI were significantly lower than those of the control subjects. The right hemisphere was involved in all cases, but the left hemisphere was involved only in severe cases. In the EB and I groups, two strong "electro-clinical" correlations were observed, each one being specific for each hemisphere, one relating the reduction of the right alpha BVI to the depressive mood, the other relating the reduction of the left alpha BVI to the degree of speech ("ideoverbal") retardation. These results emphasize the role of the right hemisphere in the probable pathogenesis of depression.

Adult↗
PubMed1992

[The configuration of a video signal digitalizing system used in astronomy for radiological applications].

A digital system of video signals of astronomical use was developed to be applied in the field of radiology. The images were obtained from radiologic films by means of a standard video camera. The minimal specifications of the digital images for use in radiology are as follows: a) 2.5 lpm spatial resolution, b) a digital resolution of 8 bits (256 gray levels). Images (194 by 154 mm in size) can be obtained. The software processing was adapted for treatment of the images in radiology.

Astronomy↗
PubMed1992

The evaluation of the changes of voice registers in trainee singers by using the two-channel signal processing method.

This study was done at the ENT Department of the Ege University Medical Faculty on twenty trainee singers. Using the two-channel signal processing method, the electroglottographic (EGG) signals and the voice signals were digitized with an analog-digital converting card during an ascending and descending glissando exercised by the trainee singer. These signals were recorded on the computer's hard disk and the obtained data was analysed. It has been determined that the EGG signals were more irregular the singing formant of the voice signal was very weak or absent and the change of register was more significant in less trained singers. This method can be used to evaluate objectively the change of voice registers in the training of the singers and be easily performed by adding an analog-digital converting card to a PC computer, without the need of expensive modern devices.

Adolescent↗
PubMed1992

Physiological bases and a technique for testing the full range of vestibular function.

The vestibulo-ocular reflex (VOR) is most active at higher frequencies (> 2 Hz) during locomotion, in order to stabilize vision. Use of active head movements, monitored by a sensor on a head strap, is a new method of testing the horizontal and vertical VORs which utilizes this natural frequency range, and doesn't require a rotating chair. Specialized computer processing based on Fourier analysis is necessary to analyze head and eye signals, which can be erratic. Higher harmonics of these erratic movements are particularly useful for VOR testing, in the analogous sense that complex sound processing is necessary for speech processing in audition. Use of portable computers with VOR active head analysis can be done at the bedside, as a portable vestibular test. Sophisticated software can effectively substitute for rotating chair hardware, provided that physiological corrections are applied to actively-generated movements at higher frequencies. In summary, the resulting test is brief, comfortable to the patient, portable, and useful for diagnostic screening over the frequency range that is most active during common daily movements.

Eye Movements↗
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↗
PubMedDate not supplied

Object-orientated DBMS techniques for time-oriented medical record.

In implementing time-orientated medical record (TOMR) management systems, use of a relational model played a big role. Many applications have been developed to extend query and data manipulation languages to temporal aspects of information. Our experience in developing TOMR revealed some deficiencies inside the relational model, such as: (a) abstract data type definition; (b) unified view of data, at a programming level; (c) management of temporal data; (d) management of signals and images. We identified some first topics to face by an object-orientated approach to database design. This paper describes the first steps in designing and implementing a TOMR by an object-orientated DBMS.

Algorithms↗
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↗
PubMedDate not supplied

Calcium signaling mechanisms in the gastric parietal cell.

Gastric hydrochloric acid (HCl) secretion is stimulated in vivo by histamine, acetylcholine, and gastrin. In vitro studies have shown that histamine acts mainly via a cAMP-dependent pathway, and acetylcholine acts via a calcium-dependent pathway. Histamine also elevates intracellular calcium ([Ca2+]i) in parietal cells. Both gastrin and acetylcholine release histamine from histamine-containing cells. In humans, rats, and rabbits, there is considerable controversy as to whether or not gastrin receptors are also present on the parietal cell. We utilized digitized video image analysis techniques in this study to demonstrate gastrin-induced changes in intracellular calcium in single parietal cells from rabbit in primary culture. Gastrin also stimulated a small increase in [14C]-aminopyrine (AP) accumulation, an index of acid secretory responsiveness in cultured parietal cells. In contrast to histamine and the cholinergic agonist, carbachol, stimulation of parietal cells with gastrin led to rapid loss of the calcium signaling response, an event that is presumed to be closely related to gastrin receptor activation. Moreover, different calcium signaling patterns were observed for histamine, carbachol, and gastrin, Previous observations coupled with present studies using manganese, caffeine, and ryanodine suggest that agonist-stimulated increases in calcium influx into parietal cells do not occur via voltage-sensitive calcium channels or nonspecific divalent cation channels. It also appears to be unlikely that release of intracellular calcium is mediated by a muscle or neuronal-type ryanodine receptor. We hypothesize that calcium influx may be mediated by either a calcium exchange mechanism or by an unidentified calcium channel subtype that possesses different molecular characteristics as compared to muscle, nerve, and certain secretory cell types such as, for example, the adrenal chromaffin cell. Release of intracellular calcium may be mediated via both InsP3-sensitive and -insensitive mechanisms. The InsP3-insensitive calcium pools, if present, do not appear, however, to possess ryanodine receptors capable of modulating calcium efflux from these storage sites.

Aminopyrine↗
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↗
PubMed1992

Intercellular calcium signaling via gap junctions in glioma cells.

Calcium signaling in C6 glioma cells in culture was examined with digital fluorescence video microscopy. C6 cells express low levels of the gap junction protein connexin43 and have correspondingly weak gap junctional communication as evidenced by dye coupling (Naus, C. C. G., J. F. Bechberger, S. Caveney, and J. X. Wilson. 1991. Neurosci. Lett. 126:33-36). Transfection of C6 cells with the cDNA encoding connexin43 resulted in clones with increased expression of connexin43 mRNA and protein and increased dye coupling, as well as markedly reduced rates of proliferation (Zhu, D., S. Caveney, G. M. Kidder, and C. C. Naus. 1991. Proc. Natl. Acad. Sci. USA. 88:1883-1887; Naus, C. C. G., D. Zhu, S. Todd, and G. M. Kidder. 1992. Cell Mol. Neurobiol. 12:163-175). Mechanical stimulation of a single cell in a culture of non-transfected C6 cells induced a wave of increased intracellular calcium concentration ([Ca2+]i) that showed little or no communication to adjacent cells. By contrast, mechanical stimulation of a single cell in cultures of C6 clones expressing transfected connexin43 cDNA induced a Ca2+ wave that was communicated to multiple surrounding cells, and the extent of communication was proportional to the level of expression of the connexin43 cDNA. These results provide direct evidence that intercellular Ca2+ signaling occurs via gap junctions. Ca2+ signaling through gap junctions may provide a means for the coordinated regulation of cellular function, including cell growth and differentiation.

Calcium↗