A data processing system adapted to the special needs of the emergency laboratory.

A data processing system for the emergency laboratory was integrated in our clinical laboratory computer system, its prime objective being the service requirements of the laboratory. It included the possibility of simultaneous optical reading of request forms and on-line capturing, processing, and printing of laboratory test data. Priority request forms, which allow the clinician to specify the interval by which emergency test results must be available, are registered by an optical reader and arranged according to urgency by the computer. The production of worksheets is replaced by visual display of information required for accurate specimen analyses on a large colour TV screen. The individual processing status of all tests from as many as 30 request forms is displayed in a colour code. For process control the updated delay time for test performance is faded in. All reports are produced by direct machine transfer of verified test results. For security purposes all steps of sample processing (request, result, report) are recorded via line printers outside the emergency laboratory. The capacity of the computer for managing sample and data processing reduces the work load for technicians. This results in a reduction of the turn-round time of tests. 95% of all requested tests are performed and reported within the requested time period and in emergencies, test results are available within 5-10 min. There has been no major breakdown of the system in over one year of use.

Performance of various mathematical methods for computer-aided processing of radioimmunoassay results.

Interpolation and regression methods are available for computer aided determination of radioimmunological end results. We compared the performance of 6 algorithms (weighted and unweighted linear logit log regression; quadratic logit log regression, smoothing spline interpolation with a large and small smoothing factor, respectively, and polygonal interpolation and the manual curve fitting on the basis of three radioimmunoassays with different reference curve characteristics (digoxin, estriol, human chorionic somatomammotrophin (HCS)). Great store was set by the accuracy of the approximation at the intermediate points on the curve, i.e. those points that lie midway between two standard concentrations. These concentrations were obtained by weighing and inserted as unknown samples. In the case of digoxin and estriol the polygonal interpolation provided the best results, while the weighted logit log regression proved superior in the case of HCS.

Demonstration of a combined deficiency of xanthine oxidase and aldehyde oxidase in xanthinuric patients not forming oxipurinol.

Genetic heterogeneity has been suggested in xanthinuria from the hitherto unexplained ability of some patients with this hereditary disorder to convert allopurinol to its active metabolite oxipurinol--an activity generally attributed to xanthine oxidase. This study provides evidence that the enzyme aldehyde oxidase is also deficient in xanthinuric patients not converting allopurinol to oxipurinol, whereas a xanthinuric patient with normal formation of oxipurinol had normal aldehyde oxidase activity. It is concluded that the enzyme aldehyde oxidase is the principal enzyme responsible for the formation of oxipurinol in man.

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.

Cluster-oriented discriminant analysis; taxonomic classification of the thyroid function.

A computer assisted procedure for the diagnosis of thyroid diseases, based on seven clinical chemical parameters, is proposed. The population studied consisted of 592 consecutive outpatients with a tentative diagnosis of thyroid disease. Thyroxine, triiodothyronine, T3 uptake test, TSH before and after TRH application, its difference and thyroxine binding globulin have been determined. The patients were clinically examined and in each case a Tc-scintigram was obtained. As a first step, 20 biochemical patterns were defined by cluster analysis (pattern cognition). T check how good in grouping process was, linear discriminant analysis was applied after which the reclassification rates were very satisfactory. The clusters found corresponded well to the pathophysiological situations with some exceptions. As a second step, patients were assigned to these patterns by use of the derived discriminant functions (pattern recognition). The proposed method seems to have some advantages over other diagnostic models published hitherto.

Evaluation of a new chemiluminescence immunoassay for the determination of human chorionic gonadotropin in serum.

A new commercially available chemiluminescence immunoassay for the quantitative measurement of human chorionic gonadotropin and its beta-subunit in serum was compared with the enzyme immunoassay used in our routine laboratory. Human chorionic gonadotropin was determined in serum from pregnant women, as well as from women with abortus imminens, suspected ectopic pregnancies or with molar pregnancies. The new human chorionic gonadotropin assay was also evaluated in combination with an automatic sample processor for distributing samples to the antibody-coated wells of the microtitre plates. The analytical precision, specificity and accuracy of the human chorionic gonadotropin assay were assessed with 152 sera, using the 60 min-incubation as well as the shorter 15 min version. Specificity was comparable with the conventional system, whereas the chemiluminescence assay performed better with respect to the assay detection limit and measuring range. The enhanced chemiluminescence system for the determination of human chorionic gonadotropin is an efficient assay which agrees well with our routine assay. In connection with an automatic sample processor it enables an advanced and versatile system for the determination of human chorionic gonadotropin in laboratories with large series. The system is rapid, easy to handle and apparently free from interference.

[Optimization of sample splitting in a centralized clinical chemical institute (author's transl)]. / Optimierung der Probenverteilung in einem zentralisierten klinischen-chemischen Institut.

Mechanized sample splitting machines controlled by a laboratory data processing system have been realized in only a few centralized laboratories. Bottlenecks and mistakes in sample processing are avoided by means of direct machine readable identification and parallel splitting of the secondary tubes. Our previous experience has shown that a strategy for sample splitting has to go far beyond these basic functional requirements. The splitting process must be suited to the organization of the particular laboratory, and it must be adjusted to deal with problems of individual samples containing analytically interfering substances, or variable splitting may be required in cases of inadequate sample volumes. In addition to sample identification, the secondary tube has to be coded with the date and the type of material. This allows cumulative on-line processing and series of analyses of different materials. A suitable positional arrangement of containers for control material must be born in mind for quality control performances. We have realized these additional requirements by means of a consequent mutual adaptation in the layout of the request form (marking of priority and additional information), the file structure of the data processing system and the control program of the sample splitting machine.

Detection of non-typical porphyrin isomers in human urines by ion-pair reversed-phase high-performance liquid chromatography.

An improved ion-pair reversed-phase high-performance liquid chromatographic system has been developed for the separation of uroporphyrin isomers I, II and III, whereas the isomers III and IV could not be resolved. Application of this method to the analysis of urines from porphyric patients indicated the presence of small amounts of the non-typical uroporphyrin isomer II. The questionable presence of the isomer IV was confirmed by acid-catalyzed decarboxylation to the corresponding coproporphyrin isomers, which were completely separated by a modified ion-pair method at elevated column temperatures. These procedures enabled the detection of small fractions of the atypical isomers II (1-3%) and IV (8-15%) besides the normal isomers I and III in urines of patients suffering from attacks of acute intermittent porphyria. Because such urines contain large amounts of porphobilinogen, the nonenzymatic self-condensation of porphobilinogen to uroporphyrinogens was studied under mild reaction conditions. In these experiments quite similar isomeric compositions were observed as compared to those in urines of patients with acute intermittent porphyria. Thus the non-typical uroporphyrin isomers II and IV present in human urines originate from a simple non-enzymatic condensation of porphobilinogen.

Isocratic ion-pair high-performance liquid chromatographic methods for the determination of uroporphyrin and coproporphyrin type II and IV isomers in human urine.

Urinary porphyrins of porphyric patients were isolated as their methyl esters by using a simple, modified thin-layer chromatographic system. Existing methods for the isocratic ion-pair high-performance liquid chromatographic separation of uroporphyrin and coproporphyrin isomers were decisively improved by elevating the column temperatures, changing the types of columns used and modifying the eluent compositions. These techniques were applied to the determination of the isomeric distribution of uroporphyrins and coproporphyrins isolated from urines of patients in the acute or latent phase of acute intermittent porphyria. In these urines relatively high contents of the atypical uroporphyrins II (2-5%) and IV (13-19%) were found. The coproporphyrin fractions contained significantly smaller amounts of the atypical isomers II (1-2%) and IV (2-5%), the presence of which was demonstrated for the first time in such urines. Several mechanisms for the formation of the atypical coproporphyrin isomers are discussed. The isocratic ion-pair separation method served also to control the isomeric purity of uroporphyrin specimens of both natural and synthetic origin.

Digitalis intoxication and treatment with digoxin antibody fragments in renal failure.

Severe digitalis intoxication today is preferentially treated by intravenous infusion of Fab fragments of digoxin antibodies (Digitalis Antidot BM). The kinetics of Fab fragments in the circulation are well known when kidney function is normal or slightly impaired. There are no data available, however, in complete renal failure. We observed a patient with life-threatening digitalis intoxication (serum digoxin, 3.7 ng/ml) and anuria, who was treated successfully by 160 mg Fab fragments i.v. Serum digoxin and Fab fragment concentrations could be followed for 229 h. The extrarenal clearance of Fab fragments was lower (5.6 ml/min) than in patients with normal kidney function (10.9 ml/min). This finding suggests that lower doses than usual might be sufficient for treating patients with severe digitalis intoxication and renal failure.

[The mechanization of the enzyme immunological determination of phenytoine with the Centrifichem (author's transl)]. / Zur Mechanisierung der enzymimmunologischen Bestimmung von Phenytoin mit dem Centrifichem

The separation of free from bound antigen is not required in homogeneous enzyme immunoassays (EMIT). Therefore this technique can easily be mechanized. For the mechanization of the enzyme immunological determination of serum levels of Phenytoine the fast analyzer (CENTRIFICHEM) was found most satisfactory in our laboratory. The marked advantages over manual methods are: 1. The amount of sample and reagents needed can be reduced by half. 2. The intra- and interassay variance are significantly better compared to values found with manual techniques. 3. 60 samples can be determined in duplicate in under two hours.

[The use of primate tissue homogenates for quality control in the creatine kinase-MB determination with inhibiting antibodies (author's transl)]. / Verwendung von Primaten-Gewebshomogenaten zur Qualitätskontrolle der Bestimmung von Kreatinkinase-MB mit inhibierenden Antikörpern.

The creatine kinase isoenzymes CK-MM, CK-MB and CK-BB from Rhesus monkey heart and brain tissue homogenates were separated chromatographically. Thereafter it could be demonstrated that the activity of the simian subunit CK-M is completely inhibited by anti-inhibitory-CK-M serum. Thus control sera from simian tissue are in principle suited for quality control in an immunological determination of creatine kinase-MB. The intra-assay variance and interassay variance were n = 56, -/x = 29.2 U/1, SD = 3.2 U/1, CV = 11.1% and n= 12, -/x = 166.7 U/1, SD = 5.0 U/1, CV = 3.0% respectively. It is desirable to develop control sera with catalytic concentrations of creatine kinase-MB in a lower range.

Steroid phosphorus compounds. V--Mass spectrometry of phosphinic esters of monohydroxy steroids.

The mass spectra of the dimethylphosphinic, dimethylthiophosphinic and dimethylphosphinous ester derivatives of several monohydroxy steroids are reported. The fragmentations of the derivatized steroids largely depend on the nature of the phosphorus-containing ester group. Phenolic ester derivatives exhibit the base peak at the molecular ion, whereas the spectra of the secondary phosphinic esters are dominated by very intense protonated phosphinic acid ions [Me2P(XH)(OH)]+ at m/e 95 (X =O) or at m/e 111 (x = s). The present results also indicate the low ionization potential for the phosphinic ester group. Due to their good gas chromatographic properties, these steroid derivatives appear to be particularly suitable for gas chromatographic mass spectrometric analysis of biochemical materials.

Analysis of free stool porphyrins by high-performance liquid chromatography.

The determination of stool porphyrins is necessary for the diagnosis of some porphyrias in clinical laboratories. Quantitative methods for the analysis of faeces for porphyrins are unpleasant and difficult to perform. An extraction and ion-pair reversed-phase high-performance liquid chromatographic procedure is described for the separation and determination of individual free stool porphyrins. The within-assay coefficients of variation range from 2 to 6%. A linear response curve is observed between 38 and 380 nmol/g for coproporphyrin I in dry stool The method can be applied to the routine analysis of free stool porphyrins in the clinical laboratory.