Volume 36, Issue 11

The ready availability of inexpensive desk-top computers with enormous disk storage has made the practicality of computer assisted medical interpretive software a reality. There seems little question that these programs could be of enormous help to physicians. However, there are daunting problems to their creation, including the lack of standards for clinical diagnostic precision or accuracy and paucity of helpful literature. As a result, the final products may be quite different. Little effort has been devoted in the laboratory to produce programs which could have great benefit in bridging the gap between laboratorians and clinicians. In a few circumscribed areas where the interpretation of laboratory measurements have been well studied in relation to patient demographics and to the final outcome, the impact has been enormous. The prime example is prenatal diagnosis of neural tube defects, and certain chromosomal and developmental abnormalities. Viewed as an obstacle by most people able and willing to attempt to create such programs is the omnipresence of necessary regulation. A brief overview of the general structure of a program to assist with the interpretation of serum proteins is given as a model in the perspective of current knowledge and state of the relevant literature.

This review describes briefly proteome science. It explains why proteome science or proteomics emerged only recently and why a shift from genomics to proteomics is occurring. This review further illustrates that proteomics can unravel new domains in nature's complexity. Finally, it demonstrates that proteomics is offering new tools for the study of complex biological or medical problems.

It is well known that peptide-producing endocrine tumours cosecrete immunoreactive chromogranin A with their characteristic hormones. Into this study 187 patients with the diagnosis malignant carcinoids or other malignancies were entered. Using chromogranin A at a cut-off level of 30.3 U/ml it was possible to discriminate between patients in remission and patients suffering a relapse with a sensitivity of 91.7% and a specificity of 96.4 %, which may be of important diagnostic value. In our study that lasted over one year we could clearly show that the measurement of chromogranin A is impressively superior to 5-hydroxyindoleacetic-acid for detecting a relapse of carcinoids.

Cancer antigen 15–3 (CA 15–3), carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA) were measured in 679 sera of breast cancer patients and in 94 sera of women without breast cancer. The tumour markers were determined using immunoluminometric assays (ILMA). The assays are characterised by an inter-assay-imprecision and intra-assay-imprecision <4 %. The breast cancer patients were staged according to the TNM classification stage 0–IV (by UICC) in patient groups with a compatible prognosis. Median and range of each stage were investigated. The cut-off values (95th and 97.5th percentile of control group) of CA 15–3, CEA and TPA were determined; specificity, sensitivity, positive and negative predictive value (PV) and efficiency were investigated for these cut-off's and the receiver operating characteristic (ROC) curves were calculated. The differences between control group and stage 0–3 were shown as non-significant for CA 15–3 and CEA but significant for TPA. Significant differences were found in stage 4 for all three tumour markers. The three tumour markers did not have differences in specificity, positive and negative PV and efficiency. TPA and CA 15–3 demonstrated comparable results in sensitivity and ROC curve analyses. These results were better than those from CEA.

A rat model is introduced which enables investigations in anticoagulated blood with continuous measurements by a flow-through electrode system. In the present study, a potentiometric ion-selective electrode (ISE)-system was used for measuring Ca 2+ , K + , Na + and pH in rats. The setup was adjusted to an extracorporeal blood-volume of 0.750 ml. This permits indirect measurements of the analytes via a dialysis membrane, with electrical separation of the ISE's and the animal. The flow-rates of blood and dialysis-solution were adjusted in such a way that water diffusing from the aqueous dialysis solution into the blood, across the dialysis membrane, does not alter the haematocrit. Polyethyleneglycol-hirudin was used for anticoagulation, since it was superior to heparin. The assembly enables continuous measurements in the living anaesthetized rat over a time period of at least 3 hours.

Twenty four hours urinary free cortisol (UFC) excretion has been determined in 35 eucortisolic control patients, in seven of them before and after tetracosactide (Synacthen®) stimulation and in 18 patients treated by anti-inflammatory steroids. Results of the new direct Immunotech RIA (DIm) were compared to those of the INCSTAR RIA kit with (ECA) or without methylene chloride extraction (DCA). In controls DIm UFC (106.2±45.8 nmol/24h) was significantly lower than DCA UFC (397±119 nmol/24h) and than ECA UFC (127±49 nmol/24h). After tetracosactide stimulation, median of DCA/DIm ratio decreased from 3.61 to 1.88 whereas ECA/DIm ratio did not change significantly (1.31 to 1.06). In treated patients most DCA and ECA results were over the upper limit of controls but only 5 DIm results were increased. DIm assay showed good specificity and practicability and may be used with benefit in the evaluation of the adrenal gland function.

Human cystatin C is a low molecular mass protein of 13359 Dalton recently proposed as a new very sensitive marker of changes in glomerular filtration rate. Serum cystatin C concentration correlates negatively with glomerular filtration rate as well as or better than creatinine. We evaluated a recently introduced automated nephelometric immunoassay for cystatin C in serum or EDTA-plasma samples on the Behring Nephelometer System. The assay consists of incubating the 100-fold diluted sample for 6 minutes with latex particles covalently coated with anti-human cystatin C antibodies, and then quantifying the change of light-scatter produced. Method reproducibility is satisfactory, the intra-and inter-assay coefficients of variation ranging from 1.58 % to 3.77 % and from 5.6 % to 11.47 % respectively. Rheumatoid factor (≤ 1116 IU/ml), bilirubin (≤ 418 μmmol/l), triglycerides (10.47 mmol/l), and haemoglobin (12 g/l) do not significantly interfere in the assay. No significant difference was found in cystatin C concentration between serum and EDTA-plasma samples. Cystatin C is stable in serum samples stored under different conditions up to one month. This method correlates well (mean difference = −0.536 ± 0.307 mg/l) with another commercially available particle-enhanced turbidimetric immunoassay. Cystatin C offers better clinical sensitivity than creatinine for discriminating patients with normal renal function and those with mild-to-moderate reduction in renal function. This method is suitable for routine cystatin C measurement, including emergencies.

We describe procedures, results and prospects of a pilot program in External Quality Assessment (EQA) of the stat test intralaboratory turnaround times. Our goals are to promote quality by systematic monitoring and comparison of performances by laboratories, continuous investigation into the state of the art of the processes from receipt of sample to transmission of results and creation of a data base for standardization of measures and definition of consensus values for turnaround time. Of 30 laboratories invited to participate, 25 took part, agreeing to record times of arrival and transmission for all determinations of three analytes (blood hemoglobin, serum/plasma potassium and plasma prothrombin time) for seven consecutive days and to continue for one or more further periods of seven days as necessary if there were less than 300 determinations for each analyte. Within a preset time limit, data were sent by e-mail on an Excel™ file and we sent back two reports per analyte, showing: i) the graph for time vs. percentage of tests completed and several measures of turnaround time; ii) results of all laboratories in graph form, allowing each laboratory to identify only its own data. The high proportion of participating laboratories among those invited (83 %) encourages us to implement the EQA program systematically, on a half-yearly basis, extending it to all laboratories wishing to participate in Italy or elsewhere in Europe.

The objectives of this paper are to update and quantify the biological effects of the most commonly used oral contraceptives (OC) on 15 biochemical tests currently determined in clinical laboratories and to compare these effects between the different types of OC. The sample population was constituted by 1604 women using combined OCs and the control group comprised 3466 women in the same age range not taking medication. Women taking OC were divided into 11 groups according to the estrogen/progestogen combination. The effects of OCs were studied after adjustment for age, weight, height, body mass index and alcohol and tobacco consumption. The changes observed with the new progestogens were less important than in the past. In comparison with the controls, the mean serum triglyceride concentration was significantly increased by ＋8.5 % to ＋36.0 % (p<0.05 to p<0.001) in each group while those of total cholesterol and γ-glutamyltransferase were increased only in 3 and 4 estrogen/progestogen combinations respectively. Conversely, the mean concentrations of alkaline phosphatase, total bilirubin, phosphate and albumin were significantly decreased. Using a discriminant analysis, three main groups according to the type of progestogen were defined: cyproterone acetate, DL-norgestrel and levonorgestrel, and all other progestogens. The changes in serum triglyceride concentration induced by OC intake must be considered by the clinician and are useful for taking a clinical and risk decision in an individual woman.

Seventy cancer patients with malignant osteolytic bone disease received pamidronate every three weeks for a maximum of six cycles. Bone resorption parameters, urinary calcium excretion, and pain parameters were assessed at baseline and throughout the study. At baseline, 80–95 % of patients showed elevated urinary pyridinoline, deoxypyridinoline, Osteomark® NTx and serum ICTP® levels, whereas only 35 % of patients had elevated urinary CrossLaps® excretion rates. During bisphosphonate therapy, significant decreases in Osteomark® NTx, CrossLaps® and calcium excretion were observed, which were not related to the clinical outcome. The baseline levels of bone resorption markers were used to predict the probability of non-progressive bone disease or reduction in pain intensity during bisphosphonate therapy. Significant predictors of non-progressive bone disease were urinary pyridinoline and serum ICTP levels; significant predictors of reduction in pain intensity were urinary free deoxypyridinoline and serum ICTP levels. Our data indicate that serum ICTP levels predict significantly the response to bisphosphonate therapy in patients with advanced malignant osteolytic bone disease. CrossLaps did not predict the clinical outcome, but decreased significantly during bisphosphonate therapy. Our data demonstrate that the different bone resorption markers are reflecting different aspects of bone metabolism, and therefore differ in their diagnostic and prognostic properties.

The field of biochemical markers of cardiac damage is in a dynamic state, with new applications continually appearing and new assays and markers being developed. These significant and sudden advancements in the development of new biochemical assays have led however to several analytical and interpretative problems. In this situation, it is essential that a uniform and rigorous outlook be maintained to ensure optimal test utilization. For these reasons, the IFCC Scientific Division recently agreed to establish a Committee on "Standardization of Markers of Cardiac Damage" (C-SMCD), inviting members from the established American and European groups to become members of this Committee. In this presentation, the premises, the issues, and the proposed plan of action of C-SMCD are presented and discussed.