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J Büttner

Publications and source records attributed to J Büttner.

At least 37 records · Page 2Linked to original sources
PubMed1997

Clinical chemistry in laboratory medicine in Europe--past, present and future challenges.

European experts in clinical laboratory sciences have different backgrounds, and development of expertise in this field started more than 100 years ago. Specific national activities have created the heterogeneity that now exists amongst the academic professional membership of more than 40 scientific societies in Europe. The recent political changes have in addition contributed to the rapidly changing profile of Clinical Chemistry and related fields. Based on a questionnaire answered by 31 national representatives, the past, present and future aspects of the European Clinical Laboratory are reviewed. Of the more than 30,000 members of national societies, the majority studied medicine (40.1%), chemistry (27.2%) and pharmacy (21.1%) with large national differences in relative percentages. Post-graduate education is provided by two thirds of the national societies. In most European countries the same experts cover not only clinical chemistry but also haematology, haemostaseology, immunology and transfusiology. National quality assurance programmes are said to be established in 25 countries, but mandatory in only 11 of them. Of the future challenges, the implementation of request strategies were named most often, with interpretative reports and preanalytical aspects estimated as similarly important. It was thought that information technology and new scientific developments would make the greatest impact in the coming years, with economic pressure being the major limiting factor. Despite these limitations an increase in the number of tests is anticipated by most representatives, supporting the assumption of an increasing role of the clinical laboratory in future clinical medicine.

Chemistry, Clinical↗
PubMed1996

The inhibition of human immunodeficiency virus proteases by 'interface peptides'.

The active human immunodeficiency virus type 1 (HIV-1) protease has a homodimeric structure, the subunits are connected by an 'interface' beta-sheet formed by the NH2- and COOH-terminal amino acid segments. Short peptides derived from these segments are able to inhibit the protease activity in the range of micromolar IC50 values. We have further improved the inhibitory power of such peptides by computer modelling. The best inhibitor, the palmitoyl-blocked peptide Pam-Thr-Val-Ser-Tyr-Glu-Leu, has an IC50 value of less than 1 microM. Some of the peptides also showed very good inhibition of the HIV-2 protease. The C-terminal segment of the HIV-1 matrix protein, Acetyl-Gln-Val-Ser-Gln-Asn-Tyr, also inhibits HIV-1 protease. Kinetic studies confirmed the 'dissociative' mechanism of inhibition by the peptides. Depending on the peptide structure and ionic strength, both dimerization inhibition and competitive inhibition were observed, as well as synergistic effects between competitive inhibitors and interface peptides.

Antiviral Agents↗
PubMed1996

[Fulminant air embolism in arthroscopy of the shoulder joint using CO2].

We report on a case of an unexpected gas embolism during an arthroscopy of a newly injured shoulder joint. We used carbon dioxide as an arthroscopic medium which has not been considered hazardous up to now. The sudden decrease of the endtidal CO2 concentration in connection with a decrease of peripheral oxygen saturation as well as the clinical symptoms led to an immediate diagnosis of gas embolism. In this case external cardiac massage and aspiration of gas from the right ventricle proved an effective treatment.

Arthroscopy↗
PubMed1994

Clinical chemistry as scientific discipline: historical perspectives.

The fundamental ideas which underlie clinical chemistry as an independent scientific field were formed over the course of centuries. Exactly 200 years ago the first modern concepts for this discipline were formulated in close connection with the restructuring of medical education during the French Revolution on the one hand, and the emergence of a new idea of a 'clinic' on the other hand. However, not until 1840 was clinical chemistry institutionalized as academic subject and simultaneously integrated into medical teaching. After about 1860, clinical chemistry was practiced by the clinicians themselves in close relationship with clinical activities, yet again with emphasis on teaching. In this period, clinics and hospitals established 'clinical laboratories'. With the start of the 20th century, after biochemistry had developed into an independent scientific field, clinical chemistry continued to evolve in close relationship with that latter discipline. This was particularly true in the United States, where an 'American School of Clinical Biochemistry' emerged which was to greatly influence the field.

Chemistry, Clinical↗
PubMed1992

The origin of clinical laboratories.

Clinical laboratories are a main attribute of clinical chemistry. Their historical development is therefore of great interest in the history of clinical chemistry. The results of a study are given which was undertaken to trace the establishment of clinical laboratories in central Europe, mainly in France, England and in the German-speaking countries. Presuppositions for the creation of these laboratories were: (i) The idea that the results of laboratory examinations can be used as "chemical signs" in medical diagnosis, and (ii) a new concept of disease which was the result of the "birth of the clinic" at the end of the 18th century. The study shows that the development of clinical laboratories began 200 years ago. Up to the end of the 19th century, three development phases can be distinguished: an early phase from 1790 to 1840, a phase of institutionalization from 1840 to 1855, and a phase of extension between 1855 and 1890. To characterize these three phases, the foundation of the laboratories, the layout of the laboratory rooms, their equipment and instrumentation, and the usual staff are described with the aid of typical examples.

Chemistry, Clinical↗
PubMed1992

[The effect of adding clonidine to mepivacaine. Axillary brachial plexus blockade].

Clonidine (Cl) added to local anaesthetics (LA) prolongs the duration of both anaesthesia and analgesia after peripheral nerve blocks. In this study, we investigated the dose-dependent effect of Cl added to mepivacaine (M) on clinical efficacy, onset, and regression time of brachial plexus block. METHODS. Ninety patients were randomly assigned to one of three groups. Every patient received 46 ml of a mixture containing 400 mg M (pH adjusted with NaHCO3 to 7.25) and either 0.9% NaCl (group A), 0.12 mg Cl (group B), or 0.24 mg Cl (group C). The axillary block was performed using the catheter technique. In a double-blind fashion, the onset of sensory and motor blockade was tested every 5 min for 30 min. Duration of anaesthesia, analgesia, and motor blockade (time between injection and return of sensation, onset of pain, or ability to move, respectively) was assessed using a questionnaire. M plasma levels were measured by HPLC in 10 patients from each group for up to 120 min. Blood pressure (BP), heart rate (HR), and respiratory rate (RR) were measured for up to 120 min. Sedation was assessed using a verbal rating scale. RESULTS. There was no difference in the onset of blockade. There was dose-dependent prolongation of the duration of anaesthesia, analgesia, and motor blockade with significant differences between groups C and A regarding all three parameters, between groups C and B regarding duration of anaesthesia, and between groups B and A regarding duration of analgesia. There was no significant difference in M plasma levels. Although there was only a slight but significant decrease in mean BP values in groups B+C and no difference in HR and RR, 2 patients (1 group B, 1 group C) had marked decreases in BP and HR (less than 70 mmHg systolic resp. less than 50/min) after 120 and 210 min. Sedation occurred in most patients receiving Cl. CONCLUSIONS. Addition of Cl to LA produces a dose-dependent prolongation of anaesthesia, analgesia, and motor blockade. Neither the onset time nor the number of patients with adequate surgical anaesthesia was influenced by Cl. Considering the M plasma levels, it is unlikely that the prolongation of the block is caused by local vasoconstriction, which is proposed to be the mechanism of action of epinephrine. The mean differences in haemodynamic parameters were not of clinical relevance, but the two dramatic drops in BP and HR, probably caused by Cl, were significant.

Adult↗
PubMed1991

[Laboratory medicine in the area of interest between medicine and science].

The scientific disciplines of laboratory medicine are analyzed from the point of view of history and the philosophy of science. The results of this study are the following: 1. Laboratory medicine is the name of a group of subjects which exist in an interdisciplinary area between medicine and science. 2. Historical development shows that these subjects arose in the 19th century when medicine adopted the "natural scientific method" and became "scientific medicine". 3. Clinical chemistry, as one example of these subjects, is analyzed in detail to understand the thinking process and the scientific method. This subject is, on the one hand, a "theoretical discipline" (like all of the natural sciences) but, on the other hand, it is a typical "practical scientific discipline" (which like clinical medicine is aimed at certain decisions and actions). 4. The disciplines of laboratory medicine have developed typical "professions" mainly because of their application in clinical practice and their commitment to patient care.

Chemistry, Analytic↗
PubMed1991

Renal abscess in childhood: diagnostic and therapeutic progress.

During the past decade new techniques such as computed tomography (CT) and ultrasonography have been reported to have changed the diagnostic investigation and treatment of renal abscess in adults. To evaluate whether similar changes have taken place in the pediatric age group, a retrospective study of all patients seen between 1979 and 1989 was performed. Seven patients, 0.8 to 14 (mean, 9) years old, with renal abscesses in eight kidneys were identified. Ultrasound and computed tomography proved to be the most valuable diagnostic tools, revealing the diagnosis by showing a hypoechoic or hypodense mass. All patients had an initial trial of intensive antibiotic treatment, which led to resolution of the abscesses in two of the eight kidneys. In all other cases the abscesses were additionally drained, which was done surgically in two and by ultrasonography- or CT-guided percutaneous drainage in four patients. Abscess cultures grew Staphylococcus aureus (three), Escherichia coli (one) and Salmonella Group B (one) and were sterile in one case. Drainage was unsuccessful in only one patient, who subsequently underwent nephrectomy for uncontrolled infection of a diffusely damaged kidney. We conclude that the diagnosis of renal abscesses is greatly facilitated by ultrasonography and CT and that most patients can be cured without operation by antibiotics and, if necessary, by additional percutaneous drainage.

Abscess↗
PubMed1991

Clinical chemistry: a professional field for physicians and natural scientists in Europe.

1. Clinical chemistry is definitely an interdisciplinary subject between natural science and medicine. The major part of clinical chemistry is natural science and therefore theoretical science. To a lesser extent, however, clinical chemistry is practical science or "action science" which is aimed at a certain action. 2. The question "Is clinical chemistry a professional field for physicians, for scientists or for both?" can be answered with the statement: It follows from its historical development and its characteristic theory and practice, and is de facto true throughout the world, that clinical chemistry is a professional field for physicians and natural scientists. 3. The broad scope of the technical field and the challenges to be expected in future within the framework of the European Community will require the recruiting aspiring clinical chemists both from medicine and from the natural sciences. 4. Qualified postgraduate training is more important than the nature of the initial study course. 5. Apart from providing special knowledge and particular abilities, postgraduate training must make the younger generation familiar with the ways of thought of the physician and of the natural scientist. 6. Successful work as a clinical chemist requires "extra-functional" qualifications, such as the ability to conduct dialogue and teamwork with the clinician. 7. The national differences which exist in the definition of the professional pattern "clinical chemist" are a hindrance to the future development of the discipline in the European Community. The starting point for recognition of the profession must be an agreed definition among the professionals of the countries of the European Community of the professional field of the clinical chemist.

Chemistry, Clinical↗
PubMed1991

Reference methods as a basis for accurate measuring systems.

Reference methods, as part of a reference system, are essential for improving the accuracy of routine methods. They can help to establish worldwide compatibility of clinical chemical measurements and they provide an objective basis for quality control measures. The subject of analytical errors is treated in detail, then the concept of reference methods is developed. This review emphasizes the fundamental metrological aspects of reference methods and reference measurement technology. An overview is given of the most important analytical principles used for reference methods in clinical chemistry. The particular problems of reference methods for the determination of the catalytic activity concentration of enzymes are outside the scope of this review.

Chemistry, Clinical↗
PubMed1991

Philosophy of measurement by means of immunoassays.

Starting from the explanation of the terms "comparison" and "quantification" a concept of a metrologically correct measuring system is derived. The paper discusses how this concept can be applied to immunoassays. The investigation led to the following conclusions: 1. Immunoassays are not principally either comparative tests or quantitative tests. Whether or not a correct measuring system can be construed for an immunoassay test depends on the intended use and the conditions in the specific individual case. 2. If certain requirements, which are discussed in detail, are fulfilled, immunoassays can be used for measuring the substance composition of biological materials. Critical points are the unambiguous definition of the "chemical entity" of the analyte to be determined (especially of macromolecules), the calibration of the measuring system by means of standards, and the problem of matrix effects.

Immunoassay↗
PubMed1991

[Alkalinization of mepivacaine for axillary plexus anesthesia using a catheter].

One disadvantage of perivascular axillary block using a catheter technique is delayed temporal development of the blockade. Some clinical studies have concluded that pH-adjusted solutions of local anesthetics produce a more rapid onset of blockade. Alkalinization of mepivacaine for brachial block produced conflicting results. In the present study, we attempted to define the effect of alkalinization of mepivacaine 1% on clinical efficacy, onset, and regression in patients undergoing upper extremity surgery with axillary block using the catheter technique. METHODS. Sixty consecutive adult patients (ASA I-II) scheduled for upper extremity surgery under axillary block, were randomly assigned to one of two groups. In a double-blind fashion, 30 patients received 40 ml 1% mepivacaine, the pH of which had been raised to 7.25 by adding 4 ml 8.4% NaHCO3, and 30 received 40 ml commercially prepared 1% mepivacaine hydrochloride solution containing 4 ml 0.9% NaCl (pH 6.0). All patients received axillary block using the catheter technique. After placement of the block, a blinded observer tested sensory and motor blockade after 2 min, 5 min and then every 5 min for 30 min in each of the terminal nerves of the brachial plexus. Sensory blockade was determined by pinprick and graded in accordance with the scale proposed by Hollmèn: 0: Normal sensation of pinprick. 1: pinprick felt as sharp-pointed but weaker compared with the same area in the other upper extremity. 2: Pinprick recognized as touch with a blunt object. 3: No perception of touch. The gradation of motor blockade was 0: normal muscular function; 1: slight depression in muscular function compared with preanesthetic strength; 2: very weak action persisting in muscles; and 3: complete block. The results for each group were compared at every time interval. Duration of blockade was compared by evaluating the rate of regression within the first 2 h after placement of the block in each group. Mepivacaine plasma levels were measured by HPLC in 10 patients of each group prior to injection and 5, 10, 15, 20, 30, 60, and 120 min thereafter. Statistical comparison was made using the chi 2 and t tests. Differences were considered statistically significant when P-values were less than 0.05. RESULTS. The bicarbonate and saline groups were similar with respect to age, height, weight, and sex distribution. Significantly more patients in the bicarbonate group showed onset of motor blockade (grade 1) after 2 min with respect in the axillary, musculocutaneous, radial, and median nerves as well as onset of sensory blockade in the same nerves with a significant difference in blockade of the radial nerve. (ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗