Biomedical subjects
Publications and source records attributed to M Römer.
We observe the noise spectrum of electron spins in bulk GaAs by Faraday-rotation noise spectroscopy. The experimental technique enables the undisturbed measurement of the electron-spin dynamics in semiconductors. We measure exemplarily the electron-spin relaxation time and the electron Landé g factor in -doped GaAs at low temperatures and find good agreement of the measured noise spectrum with a theory based on Poisson distribution probability.
Gastric distension causes cardiovascular reactions and enhances gastric compliance. Here, we investigated how these responses are related to each other, whether they change upon repeated distension and which neural mechanisms are involved. Mean arterial blood pressure (MAP) in phenobarbital-anaesthetized rats was recorded from a carotid artery and gastric compliance determined with an electronic barostat. Runs of intermittent gastric distension were generated by stepwise increments (5 mmHg) of intragastric (IG) pressure. While gastric compliance peaked at IG pressures of 20 mmHg, the change in MAP (predominantly hypotension) was largest at IG pressures beyond 30 mmHg. Repeated distension enhanced the MAP response to IG pressures beyond 35 mmHg, whereas gastric compliance was facilitated primarily at IG pressures below 20 mmHg. This facilitation of gastric compliance depended on the magnitude of the preceding distension. The MAP response to distension was enhanced by nitric oxide synthase inhibition, inhibited by subdiaphragmatic vagotomy but hardly affected by coeliac ganglionectomy. The facilitation of gastric compliance was changed by vagotomy in a complex manner but left unaltered by the other interventions. These findings show that isobaric gastric distension elicits both MAP and gastric compliance responses whose characteristics, mechanisms and sensitization properties differ profoundly.
The analytical performance of the tumour markers CA 15-3 assay, CA 19-9 assay and Ca 125 II assay on the Bayer Immuno I System was studied according to a revised version of the ECCLS guidelines (Haeckel R. In: Evaluation methods in laboratory medicine, Weinheim, VCH Verlag 1993:47-69) in a multicentre evaluation involving five laboratories. Determination of the 3 analytes generated more than 6000 data. On the Bayer Immuno I System, the imprecisions of the CA 15-3 assay, CA 19-9 assay and CA 125 II assay were better than those found for comparison methods. The median recovery over all five laboratories of system assigned values in control sera was within the 1-s range for the three tumour marker assays. No deviation of linearity could be detected experimentally for all assays. Results for patients' samples showed acceptable agreement between the Bayer Immuno 1 system and several different comparison methods in most cases. One exception was the CA 15-3 assay in comparison with the MCA assay from Roche Diagnostic Systems, where the large difference in values is due to the use of different antibodies and calibrators in the two assays. No carry-over effects could be detected. The selective Bayer Immuno 1 system is fully automated; its practicability was rated as high.
PURPOSE: When using strong oral opioids for postoperative pain management, demand titration is desirable. A device for patient controlled oral analgesia (PCORA) and first results of its use for oral titration of morphine are presented. METHODS: The PCORA-device is a modified Baxter-PCA-on-demand system (maximum bolus volume: 0.5 ml; flow rate for filling bolus volume: 0.5 ml.hr-1). The demand PCORA-volumes were measured at specific time intervals and PCORA was compared with customarily prescribed pain therapy (CPPT) for postoperative pain management. On the first postoperative day, 20 orthopaedic ASA I or II patients received, in a randomised, cross-over trial, either PCORA (300 min) followed by CPPT (300 min) (Group I) or vice versa (Group II). The PCORA-device permitted a maximum dose of 15 mg morphine per 60 min and CPPT was performed by the ward doctor or nurse. Pain intensity (101-point numerical rating scale) and side effects were evaluated at 30 min intervals. RESULTS: The accuracy of the bolus volume delivered by the PCORA-device was 89.2 +/- 0.85% (mean +/- SEM), of manufacturer's specifications. PCORA pain intensity decreased over time whereas CPPT pain intensity did not (P < 0.001). PCORA-morphine requirements were 61.5 +/- 5.2 mg (Group I) and 52.5 +/- 8.5 mg (Group II) (NS; mean +/- SEM). The handling of the PCORA-device presented no problem to any patient. CONCLUSION: Patient controlled oral analgesia is an effective and non-invasive mode of postoperative pain management. The PCORA-device is reliable and easy to use.
The analytical performance of the Ciba Corning ACS:180 automated immunoassay system was studied according to a revised version of the ECCLS guidelines and partly according to a protocol of the Société Francaise de Biologie Clinique (SFBC) in a multicentre evaluation involving three laboratories. The determination of 8 analytes yielded more than 50,000 data. The values for imprecision showed that the ACS:180 is comparable to the ES-600, and gives better results for many analytes than other comparison methods. The recovery of system-assigned values in control sera was acceptable for all analytes. The upper limits of linearity claimed by the manufacturer were confirmed for all analytes. In many cases, the results for patients' samples showed good agreement between the ACS:180 and several different comparison methods. One exception was lutropin, with a large spread of the data. Furthermore, for human chorionic gonadotropin and prostate-specific antigen, the slopes of the fitting lines were significantly higher than 1. Triacylglycerols and haemoglobin did not significantly influence the measurements of any analyte. Bilirubin affected the measurement of triiodothyronine and human chorionic gonadotropin. Significant drift or carry-over effects were not detected. The selective ACS:180 is fully automatic, requires relative short personnel time, and was easy to operate.
The analytical performance of the three analytical systems Reflotron, Ektachem DT60 and Seralyzer III was studied according to ECCLS guidelines (1) and partly according to a protocol of the Société Francaise de Biologie Clinique (SFBC) (2) in a multicentre evaluation involving four laboratories. The determination of 11 analytes led to more than 180,000 data. With the Ektachem DT60, imprecision was acceptable for all analytes except for sodium. With the Reflotron, imprecision for glucose and creatinine was wider than the acceptable limits. With the Seralyzer III, imprecision for glucose, uric acid, cholesterol, creatinine and potassium was not within acceptance limits. The recovery of system assigned control sera values was acceptable for all analytes, except for glucose, creatinine and sodium with the Ektachem DT60 system, and for all but glucose and cholesterol with the Reflotron. On the Seralyzer III, the limits of acceptance were exceeded only with the creatinine assay. The recovery of the reference method values with Kontrollogen L caused problems with all three systems and for all analytes. Only 30% of the mean values of Kontrollogen L measured with the Ektachem and with the Seralyzer III were within the limits of acceptance. 40% of the mean values determined with the Reflotron were inside these limits. The upper limits of linearity as claimed by the manufacturers were obtained with all analytes and systems with the exception of cholesterol on all systems and the creatinine assay on the Seralyzer III. The systems under test and several different comparison methods showed good agreement for the analysis of patient samples, except in one laboratory for the analysis of sodium and aspartate aminotransferase with the Ektachem system and potassium with the Seralyzer III. Turbidity showed no significant influence on the measurements of all analytes and all systems. Haemolysis, hyperproteinaemia, and bilirubinaemia affected several methods on all three systems. A start time delay of up to 60 s did not affect the results of the Reflotron, except in the case of the triacylglycerol assay, which was affected by start time delays greater than 45 s. The results of 4 assays on the Seralyzer III were decreased considerably by a delayed start time (triacylglycerols and creatinine above 5 s, aspartate aminotransferase above 35 s and creatine kinase above 15 s). For reliable results from all the assays in each of the three analytical systems, it was necessary to use the prescribed sample volume within certain limits. The practicability of all analytical systems tested was found to be very good. A field study was conducted with the Reflotron system. The analyte concentration was determined in venous blood from various patients. In 25 out of 30 experiments, the results of the "field" laboratories showed a greater spread about the fitting line than those obtained in the "expert" laboratories.
A multicentre evaluation of the blood gas-electrolyte-haematocrit-analyser BGE (Fa. Instrumentation Laboratory), following as far as possible the ECCLS guidelines for multicentre evaluation of blood gas analysers, was performed by three laboratories. The rules of the evaluation protocol were extended to the electrolyte and haematocrit determinations. The BGE proved to be easy to operate and maintain. The stability of the measuring system was good. The within-run imprecision of all electrodes was excellent. The same applies to the between-day imprecision, except for the calcium measurements. The systematic deviation of the gas electrodes was very small. Comparison studies revealed clinically significant deviations only for ionized calcium. Some suggestions for further improvements are made.
The Clinical Chemistry Analyzer Dimension 380 manufactured by Du Pont de Nemours was tested in a multicentre evaluation according to the guide-lines of the European Committee for Clinical Laboratory Standards (ECCLS) and in part to the protocol of the Société Française de Biologie Clinique (SFBC). The instrument and the reagents were evaluated as a system, since both reagents and reagent cartridges are specifically designed for the instrument. Fourteen analytes including electrolytes, substrates and enzymes were tested. The evaluators summarized their experience as follows: 1. All parameters tested yield results comparable to established procedures. 2. Very good performance of the ion-selective-electrode unit. 3. The imprecision data of the system are, for most parameters, between 1 and 4% CV and thus equal to or better than those of the instruments compared. 4. No reagent or sample carry-over was detected after a minor modification of the instrument. 5. The linearity of Dimension test methods in general covers the range stated by the manufacturer. 6. Very good stability of the calibration curves (up to 2 months). 7. Good practicability of the whole system, including handling of reagents and a very user-friendly software.
Although malignant hyperthermia is still a potentially fatal disease that was marked by a high mortality until recently, lasting damage to the patient can now be prevented by early diagnosis and treatment. The following case demonstrates the special value of capnometry in diagnosing this condition. A 34-year-old man admitted for oral surgery showed symptoms of malignant hyperthermia 5 h after induction of anesthesia. Neuroleptanalgesia had been conducted. The patient had received thiopental and fentanyl for induction of anesthesia and alcuronium and succinylcholine for intubation. The first symptom noticed was an elevation of the end-tidal pCO2 as monitored by capnometry. Additional symptoms, such as a pronounced rise in temperature, blood pressure, and heart rate did not develop until 20-25 min later. The end-tidal oxygen concentration decreased from 30 vol.-% to 26 vol.-%. The patient had to be ventilated with a volume of 25 l/min to keep end-tidal pCO2 under 6 kPa. Treatment with dantrolene was started immediately. Not until 3 h after the onset of the first symptoms did the patient's body temperature and the minute volume needed for ventilation return to normal. Postoperative laboratory findings showed only a slight elevation of creatine kinase and serum lactate. Myoglobin was not detected in serum or urine. This case indicates that capnometry permitted immediate adaptation of controlled ventilation to the patient's increased metabolic rate and early initiation of dantrolene treatment, thus preventing more severe disorders and possible consequences for the patient. Other studies have also suggested the special importance of capnometry. Since the patient refused to give his consent, the diagnosis could not be ascertained by muscle biopsy, and had to be based on symptoms.
The analytical performance of the glucose analyser ESAT 6660 from Eppendorf was studied according to the ECCLS guidelines and partly according the SFBC protocol in a multicentre evaluation involving laboratories from three European countries. The glucose determination in serum and in haemolysate was studied. The following results were obtained. 1. The precision was as good as or better than the precision of the comparison instruments. The coefficients of variation were between 1.1 and 3.4% for the between-days imprecision and between 0.35 and 1.45% for the within-run imprecision experiment. 2. The recovery of control sera values compared with the hexokinase method was between 94.3 and 102.6%. 3. With patient specimens as good agreement was found between the results obtained with the ESAT 6660 and the different comparison instruments (ASTRA, Hitachi 737 and ACP 5040). 4. A drift effect of 1.1-2.3% occurred in 5 of 21 experiments, depending on the individual enzyme membrane. 5. Sample carry-over was not observed. 6. A linearity between 0.5 and 50 mmol/l was found, exceeding the manufacturer's claims. 7. Several different endogenous and exogenous interferences were investigated. No interfering effect was detected for endogenous substances. A positive interference was observed by ascorbic acid at a concentration above 350 mg/l. 8. The practicability of the instrument was judged as very good. It was considered as a disadvantage that the instrument is not capable of piercing sample lids. Also the numeration of samples is not very convenient.
The selective multi-protein analyser Behring Nephelometer was examined according to the ECCLS guidelines in a multicentre evaluation involving five laboratories. IgG, IgA, IgM, C-reactive protein, C3c, C4, apolipoprotein A-I and B were measured in serum, and albumin and IgG were measured in cerebrospinal fluid. All values obtained were included in the evaluation without correcting for outliers. The trial, which lasted three months and involved over 20,000 analyses, basically yielded the following results: 1. The precision was generally better than that of comparative procedures. For the majority of methods, the between-day coefficients of variation were below 4.5%. The highest coefficient of variation was 7.2% (for C-reactive protein) and the lowest 1.35% (for C3c). 2. The fraction of assigned values of control materials varied between 0.95 and 1.08. 3. Good agreement was found with results from the comparison procedures: Beckman ICS, Behring Laser Nephelometer, Hyland Laser Nephelometer. 4. No carry-over effects were observed. 5. No interferences were observed for IgG, IgA and IgM determinations using hyperbilirubinaemic or haemolytic samples. In contrast lipaemic samples and some with monoclonal immunoglobulin M showed an influence on the immunoephelometric reaction. 6. Because of the large measuring range, it is necessary to repeat analyses only in extremely rare cases. 7. During the entire evaluation period no instrument malfunctions or interruptions occurred. As a result of its reliability, the Behring Nephelometer is well suited for routine operation and emergency analyses in medium and large-sized laboratories.
The analytical performance of the selective multitest ABBOTT Spectrum analyser was studied according to the ECCLS guidelines and partly the CERMAB protocol in a multicentre evaluation involving laboratories from six European countries. Fifteen analytes, including the electrolytes sodium, potassium and chloride, were measured each in at least 3 laboratories, all at 37 degrees C, except the electrolytes, which are measured at room temperature. The trial lasted approximately three months and involved the collection of over 60,000 data points. It yielded the following results: 1. The precision was at least as good as the precision obtained with the comparison instruments. The majority of the coefficients of variation were between 1 and 4%. 2. The recovery for method assigned control sera values was, with few exceptions, within 10%. 3. Good agreement with respect to the method assigned values of control materials and method comparison with patient specimens to different instruments (e.g. SMAC, Hitachi 737, RA 1000) was found. 4. No drift was observed. 5. Reagent-related carry-over was not found. Specimen-related carry-over was detected in some cases, the deviation being of little or no clinical significance. 6. The manufacturer's claims regarding method linearity were as stated or exceeded. 7. The open system capability was tested and rated as very convenient. 8. The practicability of the instrument was very good.
Although perforating injuries of the lens capsule typically lead to traumatic cataract in humans and rats, capsular healing is observed regularly in injured rabbits and dogs. This is most likely because protein exudation in rabbits and dogs is much greater than that in humans and rats. Using isolated white Wistar rat lenses, rat lenses in vivo, and isolated human lenses, we attempted both to replace lens protein as well as develop techniques for microsurgically closing the capsule by applying a fibrinogen-based tissue adhesive. This application was effective in preventing traumatic cataract. Use of a fibrinogen-glued capsule graft yielded similarly good (but not better) results.
298 patients suffering from eczema were tested for alkali-resistance by means of the method according to Burckhardt-Locher (ARBL) as well as patch-testing. If ARBL revealed decreased alkali-resistance, there was a high correlation with the outcome of the patch-test of alkalis. If ARBL showed normal values, however, additional patch-testing detected reduced alkali-resistance in 42.9% of the cases. In order to make a well-founded diagnosis of alkali-resistance, we suggest to combine both methods and/or to include a control of ARBL after 24 hours as proposed by Burckhardt.
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Using a LiF dosimeter, comparative measurements were carried out on film mammography and xeromammography on surface and exit dose to the breast and scatter at the level of the gonads. Exit dose at 200 to 330 mR was approximately the same for both methods; incident dose at 6,800 mR for film mammography was significant higher than for xeromammography at 3,800 mR (Mo tube) or 1, 200 mR (tungsten tube). Scatter at the level of the gonads for all three methods was between 4.4 and 12.8 mR. For xeroradiography of the knee joint, the radiation dose of 466 mR was approximately three times that for a film technique (160 mR).