Band 37, Heft 7

Human genetics has rapidly evolved from vague impression that descendants resemble their parents, to science which is now of utmost importance to the development of new principles and practice in medicine. It was only in the beginning of this century when it was suggested that chromosomes might carry genetic information. During the two last decades researchers have developed amazing methods to study and manipulate genes. This has created new possibilities to diagnose and cure diseases, but also raised ethical and legal questions. These developments are outlined in the present paper.

Laboratory medicine has undergone a sea change, and medical laboratories must now adapt to, and meet new, customer-supplier needs springing from shifts in the patterns of disease prevalence, medical practice, and demographics. Managed care and other cost-containment processes have forced those involved in health care to cooperate to develop a full picture of patient care, and this has affected clinical laboratory objectives, the main focus now being on improvement in medical outcomes. More recently, the resource shortages in health care and results of cost/effectiveness analysis have demonstrated that the value of a laboratory test must be ascertained not only on the basis of its chemical or clinical performance characteristics, but also by its impact on patient management, the only true assessment of the quality of testing being quality of patient outcomes. The time is ripe for changing the vision of laboratory medicine, and some of the reasons for this are the availability of results in real-time, the introduction of more specific tests, and the trend to prevent diseases rather than cure them. The information from laboratory tests designed to evaluate biochemical or genetic risk and/or prognostic factors cannot be replaced either by physical examination and/or the assessment of symptoms. Today, the importance of laboratory scientists must be proven in three broad areas: a) guaranteeing the quality of tests, irrespective of where they are performed; b) improving the quality of the service; c) maximizing the impact of laboratory information on patient management.

A heterozygous polymorphism changing GGT 40 (Gly) to AGT 40 (Ser) in the glucagon receptor gene (GCG-R) was reported to be associated with non-insulin-dependent diabetes mellitus (NIDDM). A possible involvement of this polymorphism in impaired glucose tolerance was also suggested in a French population. However, the prevalence of this polymorphism differs markedly among different ethnic groups, whereby the results in German populations were found to be contradictory. We thus investigated the association of this mutation with NIDDM and healthy subjects in 508 German subjects (196 NIDDM, and 312 controls). None of the control subjects, but one of the NIDDM patients demonstrated the Gly40Ser polymorphism. Since no first-degree relative of the index patient had this genetic variance, a de novo mutation is suggested. Although the frequency of the Gly40Ser polymorphism in NIDDM observed in France is not confirmed in our population, this genetic variance is also evident in Germany.

Mutations in the Kirsten ras 2 (K- ras ) gene were described as early events in the process of colorectal carcinogenesis. The aim of this study was to find a possible relationship between the presence of K- ras mutation in samples of primary colorectal carcinomas and the clinico-pathological data of the investigated patients. Mutation in codon 12 of the K- ras gene was determined in 18 of 53 colorectal carcinomas (34 %) in our group of patients. The presence of K- ras gene mutations was not related to gender, age of subject at diagnosis, staging or cancer location (p > 0.05). Sixteen of the 42 (38 %) moderately differentiated carcinomas, and two of the eight (25 %) well differentiated carcinomas contained K- ras mutation in codon 12, but none of the three poorly differentiated carcinomas contained the mutation. Moderately differentiated tumours contained an aspartate code GAT (in eight cases), a valine code GTT (in six cases), an alanine code GCT (in one case) and a serine code AGT (in one case) in codon 12. Well differentiated tumours contained only the valine code GTT (two cases). Our results show that the frequency of mutations in the K- ras gene in carcinomas in Central Europe is not different from the frequencies found in other parts of the world. The homogeneous incidence of K- ras mutation does not seem to be related to ethnic factors, dietary habits, or the composition of the diet.

Urinary cotinine was measured according to its inhibitory activity on the agglutination of cotinine-coated latex particles by anti-cotinine antibodies, the agglutination being measured by optical counting of the remaining non-agglutinated particles (particle counting, PaC). The detection limit was 0.03 μg/ml and the practical range extended from 0.03 to 3.9 μg/ml. The correlation results of 320 urine samples with those of high pressure liquid chromatography, enzyme-linked (Coti-Tracq EIA, Serex Inc., Maywood, NJ, USA), and fluorescence polarization immunoassay (TDX instrument, Abbott, Abbott Park, IL, USA) were r = 0.90, r = 0.69, r = 0.87, respectively, whereas the correlation coefficients between the assays other than particle counting ranged from 0.62 to 0.88. PaC does not require any separation step and can thus be easily automated.

Clinical laboratory procedures using cerebrospinal fluid (CSF) to assist in the diagnosis of multiple sclerosis (MS) are based essentially on the determination of oligoclonal bands (OB) in CSF and not in serum. To date, the techniques using isoelectric focusing (IEF) have represented one of the most efficient methods for detecting supernumerary bands in CSF but unfortunately were not always compatible with a routine use. Here, we describe a revised method of IEF suitable for the diagnosis of neurological disorders. The kit-based technique was simplified and the present procedure allowed an easier execution, reduced the overall analysis time and permitted an uncomplicated intepretation of oligoclonal profiles. Moreover, the technique developed was very sensitive and specific for the diagnosis of MS diagnosis. In conclusion, the IEF protocol described in this report is suitable for OB detection in any laboratory.

The bone mineral density (BMD) and the associated extracellular status of mineral and acid-base metabolism were evaluated in 11 males, 3–18 years after total gastrectomy (GX). In the lumbar spine, but not in the femoral neck, BMD was decreased in seven, normal in three, and falsely high in one individual. Relative to the limits of normalcy, fasting serum levels of gastrin were low, but normal for calcium, phosphorus, parathyroid hormone, calcitonin and vitamin D, while the level of total alkaline phosphatase was elevated; fasting urine pH and calcium were low, while phosphorus and net acid were high. Regression analyses revealed serum gastrin and phosphorus, and urinary net acid as possible predictors of BMD. It was concluded that over the long-term GX evokes low BMD, but not hyperparathyroidism and deranged vitamin D metabolites. Future studies may focus on gastrin, parathyroid hormone-independent hyperphosphaturia and disturbed acid-base metabolism as indicators of a new extra-cellular equilibrium of minerals.

Six assays for C-peptide were evaluated. Five assays were radioimmunoassays; one was a chemiluminescence assay. The within-run coefficient of variation ranged between 2.1 and 22.9 %. The methods correlated well with each other (r = 0.925 to 0.978). There were, however, proportional biases between the assays, in particular in the higher concentration range. All assays were linear up to at least 4.5 ng/ml C-peptide concentration. All assays were easy to perform. However, the systematic bias between the assays demonstrates that further effort is needed to standardize the measurement of C-peptide. In the meantime, we recommend that laboratories conducting C-peptide measurements establish local, method-specific reference ranges.

Urine specimens from 438 patients were examined with the UF-100 flow cytometer (Sysmex TOA Medical Electronics (Europe) GmbH, Hamburg, Germany) and by manual microscopy and test strips. One hundred and forty-two of these were also examined bacteriologically. The measurements with the UF-100 were performed on native urine without prior centrifugation. Intraassay imprecision, CV of 1.3 % (547/μl) to 8.5 % (24/μl) for erythrocytes and CV of 2.4 % ( 218/μl) to 5.6 % (10/μl) for leukocytes, are similar to those usual in clinical chemistry, and are very much better than those seen in manual microscopy of sediment. In routine use, overloading the flow cytometer by an excessive concentration of particles was observed in 9% of specimens. Such specimens should be checked visually. The UF-100 is distinctly more sensitive than manual microscopy for determining leukocytes, erythrocytes, epithelial cells and bacteria. Reference ranges were estimated from the results obtained. These enabled the UF-100 to replace routine manual diagnostic methods. Although the sensitivity is improved over manual microscopy of sediment, it is always necessary to perform parallel test strip examination when determining erythrocytes in order to detect haemolysis. In our opinion the Sysmex UF-100 is a suitable replacement for manual microscopy of urine sediment. In addition it offers an opportunity to improve standardization of basic urinalysis.

The urinary isoenzymes of β- N -acetylhexosaminidase (Hex) in newborn infants were characterised by chromatography, electrophoresis, thermodynamic analysis and through substrate specificity. No qualitative difference was found for the major Hex A and Hex B isoenzymes between full-term or premature newborns and adults, although in the latter group the relative proportion of Hex B is much lower (18.5 ± 2.7 % vs. 36.3 ± 1.0 %). An additional minor enzyme form was found in some premature newborns, which eluted from the DEAE-cellulose column at a higher concentration of NaCl than Hex A and, like this isoenzyme, is able to hydrolyse 4-methylumbellipheryl-2-acetamido-2-deoxy-β-D-glucopyranoside-6-sulphate, which would suggest that it has α subunits in its molecule. These results do not confirm the hypothesis of other authors about the existence of a unique fetal Hex isoenzyme in neonatal urine which eluted before the application of the NaCl gradient, similarly to the Hex B.