Temperature measurements in a capacitive system of deep loco-regional hyperthermia

Hyperthermia has been shown to be a medically useful procedure applicable for different indications. For the connection between clinical effects and heat, it is important to understand the actual temperatures achieved in the tissue. There are limited temperature data available when using capacitive hyperthermia devices even though this is worldwide the most widespread method for loco-regional heating. Hence, this study examines temperature measurements using capacitive heating. Bioequivalent phantoms were used for the measurements, which, however, do not consider perfusion in live tissue. In general, the required temperature impact for an effective cancer therapy should need an increase of 0.2°C/min, which has been achieved. In the described tests on the non-perfused dummy, on average, the temperature increases by approximately 2°C in the first 12 min. The temperature difference relative to the starting temperature was 10–12°C within a therapy time of 60 min (rising from the initial room temperature between 20–24°C and 32–34°C). The average deviation with three individual measurements each on different days in a specified localization was 2°C. The minimum temperature difference was 4.2°C, and the maximum value was reached in the liver with 10.5°C. These values were achieved with a moderate energy input of 60–150 watts, with much higher performance outputs still available.

These results show that the tested capacitive device is capable of achieving quick temperature increase with a sufficient impact into the depth of a body.     

Quantitative measurement of red cell antigens with Groupamatic]

Groupamatic 360 can be adapted to the quantitative measurement of erythrocyte agglutination reactions. Here the authors give the necessary conditions to obtain the best sensitivity and the best reproductibility. They have considered globular suspensions, incubation of the erythrocyte antiserums mixtures, centrifugation, agitation, photometric measurement. As concerns the quantitative technique, we used the average peripheral measurement obtained in the twleve cuvettes of the same selected disc sector. The calibration is fixed to 50 mV for a non agglutinated red cell suspension and to 950 mV for albumin in a saline solution. In these conditions, the best discrimination is obtained for agglutination with measures between 400 and 800 mV. The maximum sensitivity is reached with reactions corresponding to 600 mV, that is to say in our selected conditions with 50% of free red cells. The choice of the zone between 500 and 600 mV enables to detect variations from 1.5 to 2% in an antibody solution concentration. This zone is particularly favorable for quantitative work. Although a part of these operations in this preliminary work were manually effected, the automatic centrifugation, agitation, photometric measurement and results print out make possible a large number of measurements with very satisfactory reproductibility conditions. Besides, these experiments pointed out some factors of improvement which will be helpful for the new 360 G Groupmatic equipments.     

Suitability of capacitive sensors for measuring relative humidity in anesthetic gas systems]

A capacitive sensor was tested for its suitability for measuring relative humidity in an anaesthetic gas circuit. The valvo sensor PH1 was tested using various different anaesthetic gas mixtures. Measuring accuracy was influenced neither by such volatile anaesthetics as isoflurane and halothane, nor by oxygen or nitrous oxide. The response time of the sensor depends on its position within the gas, and in the most favourable case is about 3 minutes. The sensor is readily incorporated within an existing gas circuit. The linearity of the characteristic curve must be corrected by external electronic compensation to avoid measuring problems in the lower humidity range.     

Revisiting QRS Detection Methodologies for Portable,Wearable, Battery-Operated,and Wireless ECG Systems

Cardiovascular diseases are the number one cause of death worldwide. Currently, portable battery-operated systems such as mobile phones with wireless ECG sensors have the potential to be used in continuous cardiac function assessment that can be easily integrated into daily life. These portable point-of-care diagnostic systems can therefore help unveil and treat cardiovascular diseases. The basis for ECG analysis is a robust detection of the prominent QRS complex, as well as other ECG signal characteristics. However, it is not clear from the literature which ECG analysis algorithms are suited for an implementation on a mobile device. We investigate current QRS detection algorithms based on three assessment criteria: 1) robustness to noise, 2) parameter choice, and 3) numerical efficiency, in order to target a universal fast-robust detector. Furthermore, existing QRS detection algorithms may provide an acceptable solution only on small segments of ECG signals, within a certain amplitude range, or amid particular types of arrhythmia and/or noise. These issues are discussed in the context of a comparison with the most conventional algorithms, followed by future recommendations for developing reliable QRS detection schemes suitable for implementation on battery-operated mobile devices.     

A novel, fully implantable, multichannel biotelemetry system for measurement of blood flow, pressure, ECG, and temperature.

Biotelemetry provides high-quality data in awake, free-ranging animals without the effects of anesthesia and surgery. Although many biological parameters can be measured using biotelemetry, simultaneous telemetric measurements of pressure and flow have not been available. The objective of this study was to evaluate simultaneous measurements of blood flow, pressure, ECG, and temperature in a fully implantable system. This novel system allows the measurement of up to four channels of blood flow, up to three channels of pressure, and a single channel each of ECG and temperature. The system includes a bidirectional radio-frequency link that allows the implant to send data and accept commands to perform various tasks. The system is controlled by a base station decoder/controller that decodes the data stream sent by the implant into analog signals. The system also converts the data into a digital data stream that can be sent via ethernet to a remote computer for storage and/or analysis. The system was chronically implanted in swine and alligators for up to 5 wk. Both bench and in vivo animal tests were performed to evaluate system performance. Results show that this biotelemetry system is capable of long-term accurate monitoring of simultaneous blood flow and pressure. The system allows, within the room, recordings, since the implant transmission range is between 6 and 10 m, and, with a relay, backpack transmission distance of up to 500 m can be achieved. This system will have significant utility in chronic models of cardiovascular physiology and pathology.     

A multichannel telemetry system for autonomic neural signals, blood flow velocity, blood pressure, and ECG measurements]

A radio multichannel telemetry system has been developed for use with chronically instrumented, unrestrained, small animals. The system can simultaneously record autonomic neural signals, blood flow velocity, blood pressure, and ECG. The system is time-multiplexed and pulse width modulation (PWM)/FM device, which employs two sampling frequencies. The system is designed with 10 standard low power integrated circuits, a 3 terminal voltage regulator, and a transistor. The size is 53 x 42 x 20 mm, and the weight, including two batteries is 40 grams. The system is powered by two lithium cells, which provide 60 hours of continuous operation.     

A test system for the measurement of cellular RNA-synthesis in the human bone marrow]

A test for the cellular RNA-synthesis (incorporation of 3H-uridine in the RNA) of human bone marrow has been standardized with respect to the time of incorporation, the number of cells and the concentration of 3H-uridine. The following parameters were estimated for 500 microleter standard assay and 100 microleter aliquots for the determination of the radioactivity: time of incubation 80 min, number of nucleated cells 8 - 10(5), concentration of 3H-uridine 8,3 - 10(-6) M. Actinomycin D inhibits the RNA-synthesis to 90% in a concentration of 1.2 - 10(2) microgram/ml. The test appears generally applicable for the determination of the vitality of bone marrow after cryopreservation, the testing of cryoprotectants and haematotoxic substances and the control of the reaction of the bone marrow during chemical- or irradiation treatment of tumors.     

New measurement standard for cytofluorimetry]

New phosphor crystals, on the basis of zeolit, activated by tin (Sn), appeared to be a very suitable permanent fluorescent test-object for setting up microscopes, intructing new users and for calibrating microfluorimeters. Their properties provide the control of conditions of various fluorescent experiments in both visible and ultraviolet regions. The crystal size may vary from 1 to 100 micron along the facet. Spectral, polarization and fading fluorescence characteristics of the new crystals are described.     

Covalently coupling the antibody on an amine-self-assembled gold surface to probe hyaluronan-binding protein with capacitance measurement

Hyaluronan-binding proteins (HABPs), the important structural components of extracellular matrices, served important structural and regulatory functions during development and in maintaining adult tissue homestats. A sensitive, specific and rapid-responsing immunosensor to probe hyaluronan-binding cartilage protein was presented in this work. The novel immunosensor supplied a label-free detection method for HABP, which was based on measuring the capacitance change in-between the unlabeled HABP (antigen) and rabbit-anti-HABP (Ra-HABP, antibody). The HABP immunosensor was prepared by covalently coupling Ra-HABP on an amine-self-assembled gold surface with glutaraldehyde. The capacitance change corresponding to the concentration of HABP, the target antigen, was evaluated by an electrochemical approach called potentiostatic-step in microseconds. The immunosensor showed a specific response to HABP in the range 10-1000 ng/ml. The presented work supplied a promising clinical screening method.     

A hybrid on-line ECG segmenting system for long-term monitoring.

This paper introduces a new hybrid ECG beat segmenting system, which can be applied in the processing unit of single-channel, long-term ECG monitors for the on-line segmentation of the ECG signal. Numerous ECG segmentation techniques are already existing and applied, however sufficiently robust and reliable methods currently require more than one ECG signal channel and quite complex computations, which are practically not feasible in stand-alone, low-cost monitors. Our new system approach presents a time domain segmentation technique based on a priori physiological and morphological information of the ECG beat. The segmentation is carried out after classifying the ECG beat, using the linear approximation of the filtered ECG signal and considering the pathophysiological properties as well. The proposed algorithms require moderate computational power, allowing the practical realization in battery powered stand-alone long-term cardiac monitors or small-sized cardiac defibrillators. The prototype version of the system was implemented in Matlab. The test and evaluation of the system was carried out with the help of reference signal databases.     

Spin-state selection filters for the measurement of heteronuclear one-bond coupling constants

Novel α/β-half-filter elements are proposed for the separation of the high-field and low-field component of ¹ J _HC and ¹ J _HN splittings into different subspectra. The α/β-half-filter elements are of the same duration as the S³CT pulse sequence element and, like this, are less sensitive to cross talk between different subspectra than the original shorter α/β-half-filters. The filter elements are demonstrated with the measurement of ¹ J _HC coupling constants of C^αH groups in 2D and 3D experiments and the subspectral editing of the four different multiplet components observed in two-dimensional α/β-HSQC-α/β spectra recorded without heteronuclear decoupling in either dimension.