[Breath alcohol measuring equipment: principles for calibration]. / Atemalkohol-Messgeräte: Grundlagen der Kalibrierung.

Breath alcohol simulators with aqueous solutions of ethanol (equilibrators) are suitable for simulating the measuring process with a person, while testing different functions of an evidential breath analyser including the temperature measuring device. Therefore they are commonly used for random tests. They are unsuitable for an absolute calibration if the coefficient of solubility of ethanol can not be presumed. Absolute calibrations require the transformation of a known quantity of ethanol within a defined volume into a gaseous state. The concentration of the gas produced in such a way then has to be measured with the analyser to be tested and must be compared with the calculated value. A measuring device with a large volume piston pump was constructed for this purpose. The values of the solubility coefficient coincide with internationally used values.

[Comparative measurements with breath alcohol measuring devices]. / Vergleichsmessungen mit Atemalkoholmessgeräten.

During a drinking experiment 12 persons were tested with two different breath-alcohol analysers. Both instruments fulfill essential requirements according to the expertise of the Federal Health Office concerning the forensic applicability of breath analysers. One instrument was equipped with different measuring systems (infrared system and fuel cell). The other instrument had only an infrared system and in each case two measurements were performed with this system. With both instruments breath temperature and breath volume were determined, so that the BrAC values could be compared after they were related to the reference temperature of 34 degrees C. Taking into consideration the course of BrAC as a function of time a measuring precision of all systems was found which can be characterized by a standard deviation of less than 0.01 mg/l.

[Comparison of breath and blood alcohol concentration from measurements in police work]. / Vergleich der Atem- und Blutalkoholkonzentration aus Messungen in der polizeilichen Praxis.

4.135 measurements of breath- and blood-alcohol concentration were performed by police in 1986 and 1987 using the Alcomat A 11 (wavelength 3.4 microns). Important conclusions from these measurements can be derived with regard to legal breath-alcohol limits. The parameter for judgement is the breath- to blood-alcohol concentration ratio. Extreme deviations which have to be considered as malfunctions were found only in 0.4% of all cases, despite of the fact that not all precautions for evidential measurements are fulfilled. The reasons for malfunction may result from faulty breath- or blood-alcohol determinations or may simply be errors of transfer. The frequency of relatively too high breath-alcohol values (e.g. by interfering substances) is nearly the same as of relatively too low values (e.g. by too small breath volume). It has to be considered that the requirements according to the expertise of the Federal Health Office for evidential breath-alcohol measurements are only fulfilled partly. Especially the influence of breath-temperature is disregarded although the influence on frequency distributions is important as the comparison with other measurements demonstrates. A further result shows that the frequency distribution of the breath- to blood-alcohol ratio does not depend on blood-alcohol values.

[Detection of extraneous gases in breath alcohol analysis]. / Erkennung von Fremdgasen bei der Atemalkoholanalyse.

The influence of interfering substances on breath-alcohol measurements is handled by the OIML by giving a list of test gases and prescribing the maximum permissible cross-sensitivity of a measuring system. The expertise of the Federal Health Office for evidential breath analysers prefers an other way to detect interfering substances in expired air. By the use of two measuring systems with different analytical specificity interfering substances as e.g. methanol, isopropanol, aceton, ethylacetat, and toluene cause measured values with a difference which exceeds the limits permitted in the OIML recommendations. The same happens with interfering substances in expired air which are most commonly used by sniffers as e.g. Pattex, Uhu adhesive, or petrol.

[Recommendation for a legally valid breath alcohol measurement]. / Vorschlag zur Realisierung einer beweissicheren Atemalkoholmessung.

Evidential breath-alcohol analysis requires measuring devices which cannot yet be obtained from industrial manufacturers. In order to avoid the influence of environment and breath techniques and to relate the breath-alcohol concentration to a standard temperature of 34 degrees C it is necessary to measure the breath temperature with a special device. The required reliability of measured results can only be obtained with two measuring systems operating independently from each other. When two measuring systems of different analytical specificity towards interfering substances are used, the infrared method allows a widely selective determination of ethanol. This is a prerequisite for the legal calibration of breath-alcohol analysers.

[Criteria for the validation of forensic breath alcohol tests (results of a specialty meeting of the Society against Alcohol in Road Traffic e.V.)]. / Kriterien zur Validierung beweissicherer Atemalkoholbestimmungen (Ergebnisse einer Fachtagung des Bundes gegen Alkohol im Strassenverkehr e.V.).

According to the conception developed in the Federal Health Office a forensic breath-alcohol determination requires two independent measurements of ethanol concentration received by two measuring systems of different analytical specify in order to detect interfering substances. In addition to the two values of the breath-alcohol concentration two values of the exhaled volume, the duration of exhalation and the final breath temperature were obtained. According to the recommendations of the Organisation Internationale de Métrologie Légale (OIML) valid measurements require two breath alcohol values. The difference between the two values must not exceed prescribed limits. Furthermore the other pairs of measured values can be used for a judgement of the measuring procedure. Criteria were derived from the results of tests in practice. By application of these criteria the reliability of breath-alcohol determination is increased and an influence intentioned by the subject on measured values can be avoided.

[General practice trial with breath alcohol analysis]. / Praxiserprobung der Atemalkoholanalyse.

Breath- (BrAC) and blood-alcohol concentrations (BAC) of 42 persons are compared in a drinking experiment under conditions which approach the situation in practice. Breath-alcohol determinations consisted in double measurements and included the determination of temperature of expired air. The measured BrAC was related to a temperature of 34 degrees C and was interpolated to the time when the blood sample was taken. According to the fact that in most cases the resorption of alcohol was not yet finished, the BrAC converted by a factor 2.1 to blood equivalent values were remarkably higher than the corresponding BAC values. If only these values are taken into consideration which are measured in the period of more than 20 minutes after drinking was stopped, the converted BrAC values differ not more than +20% from BAC values.

[Influence of breath volume on alcohol analysis]. / Einfluss des Atemvolumens auf die Atemalkoholanalyse.

In order to obtain reliable results in breath-alcohol analysis it is necessary to consider alveolar air. In former examinations of the question, which part of expired air contains almost pure alveolar air, a separation between the influence of temperature and volume had not been made. Only after a temperature correction has been performed the influence of volume can clearly be seen in drinking experiments. Measurements undertaken with the ALCOMAT clearly show the influence of varied breathing techniques on the results of breath-alcohol determinations. The demand of a minimum volume in the breath test is not sufficient by itself. In order to get a correct result the expiration volume should be more than 70% of the subject's vital capacity. In case of an expired volume remarkably below 50% of the vital capacity the measured values can be more than 10% below the expected values. Such big deviations can only be the result of a deliberate inspiration and expiration technique of the subject.

[Use of breath alcohol analysis in France]. / Anwendung der Atemalkoholanalyse in Frankreich.

An alcohol legislation concerning the operation of motor vehicles exists in France since 1954. In the meantime the problem of the great number of accidents caused by drivers under the influence of alcohol has required several modifications of the legal regulations. In order to get an effective prevention of alcohol-induced traffic accidents the present and future strategy of the French authorities is mainly based on an intensified application of preliminary and evidential breath-alcohol analysis. The legal limit for breath alcohol was fixed at 0.4 mg/l without a direct reference to the blood alcohol limit.

Stability of cell size and nucleolar size in tangle-bearing neurons of the hippocampus in Alzheimer's disease.

Samples of 14 brains of autopsied patients suffering from dementia of the Alzheimer type were examined. In Congo red-hemalum stained 14-microns-thick sections of the hippocampus 15 tangle-bearing and 25-30 unaffected nerve cells of area CA1 per case were measured for cell size and nucleolar size utilizing an interactive image processing unit. In affected cells tangle size was measured too. There was no significant difference in neuron size and nucleolar size between affected and unaffected cells. In tangle-bearing cells nucleolar size and cell size were not correlated with tangle size. Since nucleolar volume can serve as an indicator of RNA synthesis of a cell, tangles themselves seem not to disturb nerve cell metabolism.

[Temperature measurement in breath alcohol analysis]. / Temperaturmessung bei der Atemalkoholanalyse.

Breath-alcohol concentration determined in expired alveolar air depends even at equal blood concentration on the temperature of the breath while leaving the subject's mouth. By using a two-stage simulator it is possible to simulate the physiological reality and to examine the measuring conditions of the temperature. The results show the essential influence of the mouthpieces and the environmental temperature on the measured values. Deviations especially appear at low environmental temperature. To reduce systematic deviations an electrically heated support of the temperature probe was developed which diminishes the influence of the mouthpieces to -0.3 degree centigrade. This device almost eliminates the influence of temperature of the environment.

[The reliability of instruments for measuring breath alcohol]. / Die Zuverlässigkeit von Atemalkoholmessgeräten.

To describe the reliability of breath-alcohol testers, values are measured which characterize precision, accuracy, analytical sensitivity, drift, and hysteresis. The instruments tested were two infrared devices (Alcomat, Alcotest 7110) and one device equipped with a fuel cell (Alcolmeter EBA). Criteria of acceptability are the limits from the first preliminary draft of recommendations by the Organisation Internationale de Métrologie Légale (OIML). The results of measurements clearly show the level of reliability of modern instruments which largely attain the OIML requirements. All measurements were performed with a simulator at 34 degrees C. Therefore the definite influence of breath temperature on the alcohol concentration could be neglected.

Polarization of nerve regeneration (electrotaxis).

Regeneration of both median nerves was studied in the rat in three different experimental models of centrocentral anastomosis through an interposed segment of pre-degenerated tibial nerve after denervation by spinal root transection. Different patterns of regeneration were observed in the anastomoses. These patterns suggest a bio-electrical polarity related to neuronal function. The present experimental model appears to offer a new opportunity to study neuronal regeneration under the influence of defined bioelectrical conditions.

The geomagnetic field: a factor in cellular interactions? I. Magnetism and Schwann cell-axon interaction in the peripheral nerves of the newborn rat.

Axonal ensheathment and myelination, one form of axon-sheath cell interaction, was studied under normal earth magnetism, in the absence of terrestrial magnetic field, and under a 5 G (0.0005 T) magnetic field. Results indicate that the geomagnetic field is necessary for the fundamental biological activity of axonal ensheathment and myelination. The exact mechanism of action remains obscure.

The influence of measurement precision on medical findings.

Medical researchers, epidemiologists and clinicians are all concerned with the observed incidence rates of various diseases and diagnostic findings. Such findings are necessarily based on imprecise procedures and instrumentation. The present study describes the theoretical extent to which the precision of instruments and procedures contributes to reported distribution curves and incidence rates of diagnostic findings. A numerical method is described for separating underlying distribution curves from the observed distribution curves which are distorted by measurement error. The method is illustrated by two examples: blood pressure measurements and QRS axis distributions in the ECG.

[Model calculations of the Energy distribution of scattered radiation in a patient (author's transl)]. / Modellrechnungen über die Energieverteilung der Patientenstreustrahlung.

To obtain quantitative results on scattered radiation produced in a patient by externally applied x-rays or gamma rays, the model of a pencil beam penetrating a water layer is used. By means of the Monte-Carlo method, the energy distribution of scattered photons in a plane parallel to the absorbing layer is calculated for primary photon energies from 60 to 1250 keV. This yields information on the distribution of single-scatter and multiple-scatter photons.