Per Simonsson

The Nordic reference interval project 2000 : recommended reference intervals for 25 common biochemical properties

Each of 102 Nordic routine clinical biochemistry laboratories collected blood samples from at least 25 healthy reference individuals evenly distributed for gender and age, and analysed 25 of the most commonly requested serum/plasma components from each reference individual. A reference material (control) consisting of a fresh frozen liquid pool of serum with values traceable to reference methods (used as the project “calibrator” for non‐enzymes to correct reference values) was analysed together with other serum pool controls in the same series as the project samples. Analytical data, method data and data describing the reference individuals were submitted to a central database for evaluation and calculation of reference intervals intended for common use in the Nordic countries. In parallel to the main project, measurements of commonly requested haematology properties on EDTA samples were also carried out, mainly by laboratories in Finland and Sweden. Aliquots from reference samples were submitted to storage in a central bio‐bank for future establishment of reference intervals for other properties. The 25 components were, in alphabetical order: alanine transaminase, albumin, alkaline phosphatase, amylase, amylase pancreatic, aspartate transaminase, bilirubins, calcium, carbamide, cholesterol, creatine kinase, creatininium, γ‐glutamyltransferase, glucose, HDL‐cholesterol, iron, iron binding capacity, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, triglyceride and urate.

5-Hydroxytryptamine stimulates the formation of inositol phosphate in astrocytes from different regions of the brain

5-Hydroxytryptamine (5-HT) stimulated the turnover of phosphoinositide in primary cultures of astroglia from the cerebral cortex, striatum, hippocampus and brain stem. Ketanserin and ritanserin, selective antagonists for the central 5-HT2 receptor, inhibited the 5-HT-stimulated formation of inositol monophosphate. In contrast, there was no statistically significant accumulation of cyclic AMP after incubation with different concentrations of 5-HT in any of the cultures studied. The results indicate that astrocytes from various regions of the brain possess 5-HT2 receptors coupled to the formation of inositol phosphates.

Prediction of relative glomerular filtration rate in adults: New improved equations based on Swedish Caucasians and standardized plasma‐creatinine assays

Objective. To evaluate newly developed equations predicting relative glomerular filtration rate (GFR) in adult Swedish Caucasians and to compare with the Modification of Diet in Renal Disease (MDRD) and Mayo Clinic equations using enzymatic and zero‐calibrated plasma creatinine assays. Material and methods. GFR was measured with iohexol clearance adjusted to 1.73 m2. One population sample (n = 436/Lund) was used to derive an equation based on plasma‐creatinine/age/gender, and a second with the addition of lean body mass (LBM). Both equations were validated in a separate sample (n = 414/Malmö). The coefficients of the equations were eventually fine‐tuned using all 850 patients and yielding Lund–Malmö equations without (LM) and with LBM‐term (LMLBM). Their performance was compared with the MDRDCC (conventional creatinine calibration), MDRDIDMS (isotope dilution mass spectroscopy traceable calibration) and Mayo Clinic equations. Results. The Lund equations performed similarly in both samples. In the combined set, the Mayo Clinic/MDRDCC resulted in +19.0/+10.2 % median bias, while bias for the other equations was<10 %. LMLBM had the highest accuracy (86 % of estimates within 30 % of measured GFR), significantly (p<0.001) better than for MDRDIDMS (80 %). In men with BMI<20 kg/m2, MDRDIDMS/LM had +46 %/+19 % median bias. MDRDIDMS also overestimated GFR by 22 %/14 % in men/women above 80 years of age. The LMLBM equation had<10 % bias irrespective of BMI, age or GFR except for a 15 % negative bias at GFR⩾90 mL/min/1.73 m2. Conclusion. The newly developed Lund–Malmö equations for GFR estimation performed better than the MDRDIDMS and Mayo Clinic equations in a Swedish Caucasian sample. Inclusion of an LBM term improved performance markedly in certain subgroups.

Expression of trkB in Human Neuroblastoma in Relation to MYCN Expression and Retinoic Acid Treatment

Expression of full-length trkB can be found in some highly malignant neuroblastoma tumors with an amplified MYCN gene. This contrasts sympathetic neuroblasts, from which neuroblastomas are thought to arise, which neither express trkB nor are dependent on the p145trkB ligands, brain-derived neurotrophic factor (BDNF) or neurotrophin-4/5, for their normal development. In this study we show that trkB was expressed in two out of five neuroblastoma tumors with amplified MYCN, while no trkB expression was observed when the MYCN gene was overexpressed in a non–MYCN-amplified neuroblastoma cell line. This shows that MYCN overexpression per se is not sufficient to induce trkB expression. trkB expression and BDNF responsiveness in neuroblastoma cells can be induced by all-trans-retinoic acid (RA). When SH-SY5Y cells were stimulated with a combination of RA and BDNF, norepinephrine and tyrosine hydroxylase levels were unaltered, showing that the cells did not change toward a more catecholaminergic sympathetic phenotype. However, expression of growth-associated protein 43, indicative of a neuronal phenotype, was elevated. Vesicular acetylcholine transporter, choline acetyl transferase, and neuropeptide tyrosine mRNA levels also increased in RA-BDNF–treated cells, which could suggest that these cells develop into a sympathetic cholinergic phenotype. In addition, treatment with RA-induced expression of the platelet-derived growth factor receptor-α. As previously shown for BDNF, platelet-derived growth factor stimulated growth of the RA-treated cells, findings that could have clinical relevance. If these receptors mediate a mitogenic signal in vivo also, this might limit the effect of RA treatment on neuroblastoma patients.

Total nucleated cell differential for blood and bone marrow using a single tube in a five-color flow cytometer.

Flow cytometry allows the use of several antibodies in addition to light scatter, and most flow cytometers will provide at least seven measurements on each cell passing through the laser beam. A skilled microscopist will classify at least 14 cell classes in bone marrow or blood. Our goal was to use the seven parameters available in our flow cytometer to provide a reliable differential count using only one tube.

The 5-hydroxytryptamine stimulated formation of inositol phosphate is inhibited in platelets from alcoholics

The accumulation of inositol monophosphate (IP1) was measured after stimulation of 5-hydroxytryptamine2 (5-HT2) receptors on platelets from alcoholics and healthy controls. In controls, 5-HT induced a dose-dependent response with an EC50 = 2 x 10(-6) M and a maximal response at 10(-5) M. Ritanserin, a selective 5-HT2 antagonist, markedly reduced the accumulation. The IP1 formation after stimulation by 10(-5) M 5-HT was significantly impaired in platelets from alcoholics as compared to controls. This study indicates that the 5-HT2 receptor function is inhibited in alcoholics. It also illustrates the possibility of using IP1 formation in peripheral cells as a mean of studying receptor function in disease.

Nordic Reference Interval Project Bio-bank and Database (NOBIDA): a source for future estimation and retrospective evaluation of reference intervals

In the Nordic Reference Interval Project 2000 (NORIP) serum, Li‐heparin plasma and EDTA buffy coat were collected at 102 laboratories in 5 Nordic countries from healthy individuals aged 18 years or more and evenly distributed for laboratory, gender and age. Multiple aliquots of these samples from each of about 3000 persons are now stored at the Nordic Reference Interval Project Bio‐bank and Database (NOBIDA) at a temperature of below −80°C. The commutable NFKK Reference Serum X with certified values traceable to reference methods and measured in NORIP in the same series as the samples is also available from NOBIDA. Data describing the person and the sample conditions are stored together with analytical results and data describing the measurement systems. The bio‐bank along with material and data is administered by the NOBIDA committee on behalf of the NFKK (Scandinavian Society of Clinical Chemistry) to be used by Nordic laboratories for any purpose beneficial to the development of clinical biochemistry in general and particularly for creating reference intervals for other biochemical properties than those established by NORIP. Furthermore, research on the already stored information alone is encouraged. Thus colleagues are now welcome to use this extensive material for research and development in clinical biochemistry.

The role of monoamines in suicidal behavior

Cerebrospinal fluid (CSF), urine, platelet and neuroendochrine challenge tests of monoaminergic function give evidence of monoamines, especially serotonin, playing an important role in suicidal behavior. However, additional clinical, social and biochemical factors are necessary to better define suicide‐prone psychiatric patients.

Phosphatidylethanol affects inositol 1,4,5-trisphosphate levels in NG108-15 neuroblastoma x glioma hybrid cells

Abstract: Phosphatidylethanol is formed by phospholipase D in animal cells exposed to ethanol. Previous reports have demonstrated that the degradation of phosphatidylethanol is slow, indicating that this lipid may be present in the cells after ethanol itself has disappeared. Accumulation of an abnormal alcohol metabolite may influence cellular functions. In the present study, cultivation of NG108–15 neuroblastoma × glioma hybrid cells in the presence of ethanol resulted in an accumulation of phosphatidylethanol and a simultaneous increase in basal inositol 1,4,5‐trisphosphate levels. The direct effects of phosphatidylethanol on the phosphoinositide signal transduction system were examined through incorporation of exogenous phosphatidylethanol into membranes of ethanol‐naive cells. An incorporation amounting to 2.8% of cellular phospholipids was achieved after a 5‐h incubation with 30 μM phosphatidylethanol. Phosphatidylethanol was found to cause a time‐and dose‐dependent increase in the basal levels of inositol 1,4,5‐trisphosphate. The effects on inositol 1,4,5‐trisphosphate levels of exogenously added phosphatidylethanol and ethanol exposure for 2 days were not additive. No effect on bradykinin‐stimulated inositol 1,4,5‐trisphosphate production could be detected. However, the increase in basal inositol 1,4,5‐trisphosphate levels indicates that phosphatidylethanol affects inositol 1,4,5‐trisphosphate turnover and emphasizes the importance of considering phosphatidylethanol as a possible mediator of ethanol‐induced effects on cellular processes.

G proteins coupled to phospholipase C : molecular targets of long-term ethanol exposure

Abstract: Long‐term ethanol exposure is known to inhibit bradykinin‐stimulated phosphoinositide hydrolysis in cultures of neuroblastoma × glioma 108–15 cells. In the present study, [3H]bradykinin binding, GTP‐binding protein function, and phospholipase C activity were assayed in cells grown for 4 days in 100 mM ethanol with the aim of elucidating the molecular target of ethanol on signal transduction coupled to inositol trisphosphate and diacylglycerol formation. Ethanol exposure reduced guanosine 5′‐O‐(3‐thiotriphosphate) [GTP(S)]‐ and, to a lesser extent, NaF/AlCl3‐stimulated phosphoinositide hydrolysis, whereas it had no effect on the enzymatic activity of a phosphatidylinositol 4,5‐bisphosphate‐specific phospholipase C. [3H]Bradykinin binding in the absence of GTP(S) was not influenced by ethanol exposure. However, the reduction in [3H]bradykinin binding seen in control cells after addition of GTP analogue was inhibited in cells grown in ethanol‐containing medium. The results indicate that long‐term ethanol exposure exerts its effects on receptor‐stimulated phosphoinositide hydrolysis primarily at the level of the GTP‐binding protein.