A model for quality achievement--the NORDKEM protein project.

UNLABELLED: The Nordic protein project demonstrates a model for the process of achieving analytical quality. GOAL: based on use of common reference intervals leading to the quality specifications. Creation of quality: through common high quality calibrator (with IFCC-values) (external factor) and individual trouble-shooting and guidelines (internal factor). Control of quality: with specially designed set of control samples and problem-related evaluation of control data. Establishing common reference intervals: through associated projects.

A programme for assigning target values for external quality assessment schemes in countries with no authorized reference laboratories. Annex. Experiences with deviating results on Ektachem 700 XR.

The use of consensus values in external quality assessment schemes (EQAS) involves several problems and should preferably be replaced with target values obtained by methods of high metrological level. However, such values are difficult to obtain. In the present study we transferred values from the NIST (former NBS) certified reference serum SRM 909 to lyophilized and frozen test sera for various inorganic components using flame absorption or flame emission spectrometry. Enzyme values were assigned by laboratories of members of the former Scandinavian Enzyme Committee. The assignment was based on 2-4 determinations each day through 3 days of experiment. A total of 10 laboratories participated in the work. The results were utilized in a Danish EQAS. One practical concern is the fairly long time (9 months) which was needed for production, collection and compiling all data. To get an impression of how much dry chemistry analysers, e.g, could influence consensus values a Kodak Ektachem 700 XR was studied using lyophilized and frozen sera. The results are reported in the annex. On NIST SRM 909 the values found for sodium(I) were 6% too high even though the findings on frozen human sera were accurate. For aspartate aminotransferase a result three times the target values was found on a human lyophilized serum, while the values on the frozen sera only were slightly too high.

External analytical quality assurance for proteins.

In the Nordic Protein Project an external control scheme (external quality assessment) was combined with the two other indispensable aspects of analytical quality, i.e. standardization (with a common high quality calibrator) and specification of needed analytical quality for sharing common reference intervals for nine serum proteins in the Nordic countries. The quality specifications are reliable for the purpose and given in clinical chemical terms--ready for application to the control systems. Further, a control design for disclosing external and internal errors, separately, is designed with respect to calibration and robustness towards analytical interference from turbid patient samples.

Leukocyte glutamate dehydrogenase and CSF amino acids in late onset ataxias.

Leukocyte glutamate dehydrogenase (GDH) activity was measured in 11 healthy control subjects, 16 neurological controls, 12 patients with dominant late onset ataxia, 15 with sporadic late onset ataxia and 8 with alcoholic cerebellar ataxia. Serum hexosaminidase activity was also determined in ataxic patients. Concentrations of free amino acids were determined in the lumbal CSF of 16 neurological controls, 8 patients with late onset ataxia and 5 with alcoholic ataxia. Mean total GDH activity was reduced significantly in dominant (p less than 0.05) and sporadic (p less than 0.01) cerebellar ataxia, while the heat-labile form was decreased significantly (p less than 0.01) only in sporadic ataxia. All GDH activities were within normal range in patients with alcoholic ataxia. The serum hexosaminidase activities were also within reference range in all patient groups. The CSF concentrations of alanine, glycine, methionine and valine were significantly elevated and those of GABA and glutamate were normal in patients with late onset ataxia as compared to neurological controls. The most significant (p less than 0.01) increase was found for methionine. The amino acid levels of patients with alcoholic ataxia did not differ from those of the controls. The results suggest that GDH activity is only partially decreased in some ataxic patients and that altered amino acid metabolism may be reflected in the CSF.

Leukocyte glutamate dehydrogenase and CSF amino acids in late onset ataxias.

Leukocyte glutamate dehydrogenase (GDH) activity was measured in 11 healthy control subjects, 16 neurological controls, 12 patients with dominant late onset ataxia, 15 patients with sporadic late onset ataxia and 8 with alcoholic cerebellar ataxia. Serum hexosaminidase activity was also determined in ataxic patients. Concentrations of free amino acids were determined in the lumbal CSF of 16 neurological controls, 8 patients with late onset ataxia and 5 with alcoholic ataxia. Mean total GDH activity was reduced significantly in dominant (p less than 0.05) and sporadic (p less than 0.01) cerebellar ataxia, while the heat-labile form was decreased significantly (p less than 0.01) only in sporadic ataxia. All GDH activities were within normal range in patients with alcoholic ataxia. The serum hexosaminidase activities were also within reference range in all patient groups. The CSF concentrations of alanine, glycine, methionine and valine were significantly elevated and those of GABA and glutamate were normal in patients with late onset ataxia as compared to neurological controls. The most significant (p less than 0.01) increase was found for methionine. The amino acid levels of patients with alcoholic ataxia did not differ from those of the controls. The results suggest that GDH activity is only partially decreased in some ataxic patients and that altered amino acid metabolism may be reflected in the CSF.

Reference intervals for immunoglobulins IgA, IgG and IgM in serum in adults and in children aged 6 months to 14 years.

Reference intervals were estimated for immunoglobulins IgA, IgG and IgM in serum in 313 healthy adults aged 17 to 64 years and in 399 children aged 6 months to 14 years. In adults a nonparametric method was chosen for estimating reference interval limits. In children the limits were estimated age-specifically using regression analysis. Immunoglobulin assays used in this study were standardized with a Finnish secondary standard which was calibrated against the World Health Organisation 67/99 immunoglobulin standard. Later, another international primary standard (US National protein standard preparation) was used, the immunoglobulin levels of which are calibrated against the WHO standard. The nominal immunoglobulin concentrations assigned by the manufacturers of several commercial immunoglobulin standard preparations were found to differ from the concentrations measured with the international calibrator used in this study. In conclusion, the reference intervals estimated in this study should be transferable to any laboratory using immunoglobulin assays calibrated against the WHO standard. The usefulness of commercial immunoglobulin standard preparations not calibrated against these primary standards is limited.

Basic urinalysis and urine culture: Finnish recommendations from the working group on clean midstream specimens.

A recommendation for basic urinalysis and urine culture is published as an attempt to improve the clinical value of urinary tests and to create a system that utilizes laboratory work as sensibly as possible. More clinical background information is needed when basic urinalysis and urine culture is performed in stages. Collection and storage of urine specimens are standardized in addition to used equipment and bacterial culture. Cytological supravital stain improves qualitative and quantitative findings of urine sediment cytology. A close cooperation between central hospital district is necessary and stressed for further bacterial cultures in more complicated microbiological findings.

Finnish recommendation for methods used in urinalysis: results for five-year period.

A recommendation concerning basic urine examinations and bacteriological cultures was published in 1983 in Finland including three clinical indication groups with different screening strategies. Close cooperation between laboratory experts and clinicians as well as much training in urine sediment cytology were essential before the new principle became widely accepted. Decreased workload in laboratories in clinically less significant cases was shown with the use of the full capacity and qualities of complete urinalysis when needed. Standardized test procedures combined with sediment staining improved the clinical efficiency of urine microscopy.

SCE Nordic alpha-amylase study. II: Assessment of proposed calibration procedure. A report by the Scandinavian Committee on Enzymes (SCE).

Eighty-seven Nordic Hospital laboratories participated in a joint SCE-NORDKEM follow-up study of the long-term stability of the previously established calibration factors for a number of alpha-amylase routine methods based on six different substrates. Human control materials with 90% pancreatic, 90% salivary, and pure pancreatic alpha-amylases were measured by the participants. The data were plotted before and after calibration of each method using a human pancreatic calibrator with an assigned catalytic concentration of 390 U/l (Phadebas blue starch method, 37 degrees C). As in the previous study, carried out 9 months earlier, the pre-calibration values varied over a six-fold range. The post-calibration values of all methods except those based on a tetraose substrate showed an acceptable inter-laboratory comparability. As a temporary measure, SCE recommends that the Nordic laboratories calibrate the accepted routine methods by their individual calibration factor. Detailed suggestions for calibration procedures and a discussion of the principles of transferability will shortly be published by the SCE in this journal.

SCE Nordic alpha-amylase method selection and calibration study. A report by the Committee of Enzymes of the Scandinavian Society for Clinical Chemistry (SCE).

Seventy-six Nordic routine laboratories participated in a joint SCE-NORDKEM study comprising evaluation, selection, and temporary calibration of amylase methods. Human control materials with known fractions of salivary and pancreatic amylase were determined by seven routine amylase assays based on substrates with glucosyl (G) chain lengths G4, G5, G5-6, G7, G9, amylopectin and blue starch polymer (Phadebas). The data were plotted before and after calibration of each method using a human pancreatic calibrator with an assigned value of 390 U/l (37 degrees C, Phadebas). the study led to three conclusions: The analytical overestimation of salivary to pancreatic amylase ratio (S:P) increased with decreasing number of glucosyl units in the substrates. Relative to the S:P value of blue starch polymer (set at 1.00), for example, tetraose mean S:P value was 1.55. The hydrolysis rates relative to that with blue starch polymer decreased with the number of glucosyl units in the substrates. The precalibration values of all methods spread over an approximately six-fold range. Post-calibration values of all methods, except tetraose, showed an acceptable inter-laboratory comparability. The CV values for low, medium, and high controls were about 5.5, and 6% respectively. As a temporary solution to the current problem of diverse amylase assays, the SCE suggests calibration of the methods considered acceptable in this study. The long-term effects will be evaluated in a follow-up study within a year.

CSF in Alzheimer's disease. Studies on blood-brain barrier function and intrathecal protein synthesis.

Serum and cerebrospinal fluid (CSF) from 22 ambulatory and 10 institutionalised patients with Alzheimer's disease (AD) and 22 age-matched controls were assayed nephelometrically for concentrations of IgG, IgA, IgM, haptoglobin, transferrin, prealbumin and albumin. The CSF/serum ratio and index were calculated for each protein. In the CSF of ambulatory patients IgG, transferrin and albumin were elevated while the institutionalised patients had higher IgG and IgA levels compared to the controls. The CSF haptoglobin was elevated in institutionalised AD patients compared to those who were ambulatory. The CSF/serum ratio for albumin was elevated in both groups. An increase in the IgG ratio was also found in both groups. The ratios for haptoglobin and prealbumin were markedly increased in the institutionalised patients. CSF indices gave no evidence for increased intrathecal synthesis of any of the proteins investigated. The increased CSF/serum ratios for IgG and albumin and also the higher CSF albumin in patients with AD suggest an increased blood-brain barrier permeability in this disease. The high prealbumin ratio may be related to amyloidogenesis often present in AD.

Chromatofocusing of glutathione S-transferases from human kidney.

The glutathione S-transferase isoenzyme patterns of four human kidneys have been determined by chromatofocusing. The elution profiles were essentially similar in each tissue. Two major basic transferases and one acidic were partially characterized. All three were inhibited by bilirubin but considerable differences were found in the rate and extent of inactivation. The molecular weights, KM values and pH optima were similar to the values for transferases from other tissues. Chromatofocusing was found to be effective for the separation and purification of human glutathione transferases.

Trial with human leucocyte interferon and vidarabine in herpes simplex virus encephalitis: diagnostic and therapeutic problems.

A combination therapy of human interferon, vidarabine, and dexamethasone was administered to six patients with proven (Patients I-III) or presumed (Patients IV-VI) herpes simplex virus encephalitis (HSVE). Interferon combined with dexamethasone was given to one patient with presumed HSVE (Patient VII). Leucopenia and elevated serum transaminase levels appeared in all patients and a diffuse bleeding in one of them. Patients II, III and IV died, 26, 43, and 209 days after the onset of encephalitis, respectively. Patients I, V, VI, and VII were left with moderate brain damage although their physical condition was good. HSV encephalitis presents diagnostic difficulties, complementary diagnostic methods are needed, and current therapeutic trials must be considered as preliminary.

Juvenile metachromatic leukodystrophy. Clinical, biochemical, and neuropathologic studies in nine new cases.

We describe nine patients with metachromatic leukodystrophy. Seven patients had the juvenile form; in two others, the age at onset was 1 year, but the clinical course was different from the late infantile form. The age at onset ranged from 1 to 18 years; the duration ranged from three to 17 years. Mental retardation associated with motor impairment and pathological EEG and electromyographic findings were the main clinical findings. In patients with early onset, mental retardation was almost the only symptom for the first ten years. Segmental demyelination, remyelination, onion bulb formation, and occasional perivascular macrophages containing metachromatic lipid were the main findings in sural nerves studied after biopsy. The mean arylsulfatase-A (ASA) activity was 1.3 nmoles of nitrocatechol sulfate per milligram of protein per 30 minutes in peripheral leukocytes of the patients, 62.0 in the heterozygotes, and 139.0 in the controls. The ASA band could not be detected in enzyme electrophoresis.

Arylsulphatase A and B in juvenile metachromatic leukodystrophy.

A series of five living patients with juvenile metachromatic leukodystrophy (MLD), ten first-degree relatives, and a number of controls were subjected to biochemical investigations including quantitative determination of arylsulphatase A (ASA) and B (ASB) activities in peripheral leukocytes and polyacrylamide disc gel elctrophoresis of arylsulphatases. Five relatives were family members of four previously deceased patients with juvenile MLD. The mean ASA activity of the patients was 1.3 nmol of p-nitrocatechol sulphate hydrolysed in 30 min per mg protein. It was 84 nmol in the relatives, 129 nmol in other neurological patients and 136 nmol in normal controls. The corresponding ASB activity was 38 nmol in the patients, 49 nmol in the relatives, and 99 nmol in normal controls. An extremely low ASB activity, 3.4 nmol, was found in one relative. No ASA band could be visualised in the enzyme electrophoretic patterns of the patients' leukocytes but the bands representing ASB appeared normal. Seven relatives showed ASA bands weaker than normal, and the relative with low ASB activity exhibited very weak ASB band. The low ASB activity in the patients and heterozygotes may be a characteristic feature of the slowly progressive juvenile type MLD diagnosed in the present series.