Anders Kallner

Supplementation with vitamins C and E inhibits the release of interleukin‐6 from contracting human skeletal muscle

Contracting human skeletal muscle is a major contributor to the exercise‐induced increase of plasma interleukin‐6 (IL‐6). Although antioxidants have been shown to attenuate the exercise‐induced increase of plasma IL‐6, it is unknown whether antioxidants inhibit transcription, translation or translocation of IL‐6 within contracting human skeletal muscle. Using a single‐blind placebo‐controlled design with randomization, young healthy men received an oral supplementation with either a combination of ascorbic acid (500 mg day−1) and RRR‐α‐tocopherol (400 i.u. day−1) (Treatment, n= 7), or placebo (Control, n= 7). After 28 days of supplementation, the subjects performed 3 h of dynamic two‐legged knee‐extensor exercise at 50% of their individual maximal power output. Muscle biopsies from vastus lateralis were obtained at rest (0 h), immediately post exercise (3 h) and after 3 h of recovery (6 h). Leg blood flow was measured using Doppler ultrasonography. Plasma IL‐6 concentration was measured in blood sampled from the femoral artery and vein. The net release of IL‐6 was calculated using Ficks principle. Plasma vitamin C and E concentrations were elevated in Treatment compared to Control. Plasma 8‐iso‐prostaglandin F2α, a marker of lipid peroxidation, increased in response to exercise in Control, but not in Treatment. In both Control and Treatment, skeletal muscle IL‐6 mRNA and protein levels increased between 0 and 3 h. In contrast, the net release of IL‐6 from the leg, which increased during exercise with a peak at 3.5 h in Control, was completely blunted during exercise in Treatment. The arterial plasma IL‐6 concentration from 3 to 4 h, when the arterial IL‐6 levels peaked in both groups, was ∼50% lower in the Treatment group compared to Control (Treatment versus Control: 7.9 pg ml−1, 95% confidence interval (CI) 6.0–10.7 pg ml−1, versus 19.7 pg ml−1, CI 13.8–29.4 pg ml−1, at 3.5 h, P < 0.05 between groups). Moreover, plasma interleukin‐1 receptor antagonist (IL‐1ra), C‐reactive protein and cortisol levels all increased after the exercise in Control, but not in Treatment. In conclusion, our results show that supplementation with vitamins C and E attenuated the systemic IL‐6 response to exercise primarily via inhibition of the IL‐6 protein release from the contracting skeletal muscle per se.

GLOMERULAR FILTRATION RATE : A COMPARISON BETWEEN CR-EDTA CLEARANCE AND A SINGLE SAMPLE TECHNIQUE WITH A NON-IONIC CONTRAST AGENT

An algorithm for the calculation of the glomerular filtration rate (GFR) from a single-point determination of the serum concentration of the non-ionic contrast medium iohexol has been evaluated. The algorithm is based upon the assumption that the distribution volumes of iohexol and 51Cr-EDTA are similar. It includes correction factors for non-immediate mixing and irregular extracellular distribution during the elimination phase. The calculated GFR from single-point determinations of iohexol obtained at 180, 200, 220 and 240 min after injection of 5 mL of this compound (300 g iodine/L) were compared with the results from simultaneously performed 51Cr-EDTA clearance in 98 patients. The single-point iohexol clearance values calculated from the different sampling times showed a coefficient of correlation of more than 0.95 to 51Cr-EDTA clearance.

Does the uncertainty of commonly performed glucose measurements allow identification of individuals at high risk for diabetes

Abstract Revised recommendations for diagnosis of diabetes introduce the intermediary risk group of impaired fasting glucose (IFG), defined as individuals with a fasting blood-glucose concentration between 5.6 and 6.0 mmol/l. We apply the concept of uncertainty to identifiable steps of sampling and measuring blood-glucose. Since many instruments in primary health care measure plasma-glucose and report results as blood-glucose and vice versa, factors affecting the transformation are also considered. The study identifies the measurement procedure as the major source of uncertainty, closely followed by preanalytical sources. The estimated uncertainties indicate that the presently available procedures do not allow identification of IFG by a single investigation. The approach to establish an uncertainty budget can be used to evaluate the clinical usefulness of measurements.

Concentrations of vitamin C, vitamin B12 and folic acid in patients treated with hemodialysis and on-line hemodiafiltration or hemofiltration

Objective. Uncertainty has arisen as to whether vitamin supplements are needed by dialysis patients, in particular those treated by means of hemofiltration or hemodiafiltration using highly permeable (high-flux) filters. We therefore measured the concentrations of vitamin C, cobalamin (vitamin B12) and folic acid in conventional (low-flux) dialysis patients and in those receiving on-line treatment (hemofiltration or hemodiafiltration). Material and methods. Plasma (P-)ascorbate, serum (S-)cobalamin and S-folate concentrations were measured before and after a treatment session in 15 patients treated with low-flux hemodialysis and in 14 treated with on-line hemofiltration or hemodiafiltration. The patients’ vitamin supplementations were also recorded. Results. P-ascorbate concentrations were lowered by 51% and 53% in the hemodialysis and on-line groups, respectively after treatment and this reduction was significant (p<0.001). Concentrations below the reference values were found in 12/14 patients not receiving vitamin C supplementation. S-cobalamin did not decrease in the hemodialysis or on-line groups. S-folates did not change significantly in the hemodialysis or filtration groups. Patients without folacin supplementation had low values. Conclusions. P-ascorbate was reduced by both dialysis and filtration treatments. Neither S-cobalamin nor S-folate were reduced by dialysis or filtration treatments.

Increased Concentrations of Lactate Dehydrogenase in Pregnancy with Preeclampsia: A Predictor for the Birth of Small-for-Gestational-Age Infants

Lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) concentrations and platelet counts were measured in 26 normal pregnant women and 51 preeclamptic women. In the normal-pregnancy group, no significant changes were found in the results of these tests. In the preeclampsia group, ALT and AST concentrations were not significantly higher than those in normal pregnancy, but the LDH concentrations increased and the platelet counts decreased significantly through the pregnancy. The increases in LDH did not correlate with changes in ALT or AST. Preeclamptic women with small-for-gestational-age (SGA) infants had significantly higher LDH concentrations than those in the appropriate-for-gestational-age (AGA) group, but ALT and AST concentrations did not increase significantly. As reasons for the LDH increase in our subjects, liver damage was excluded and more active glycolysis in addition to severe cell damage due to chronic anoxemia were inferred. It is suggested that an increase in LDH is predictive of SGA infants in preeclamptic pregnancy, especially in those with normal liver function.

Can Age and Sex Related Reference Intervals Be Derived for Non-Healthy and Non-Diseased Individuals from Results of Measurements in Primary Health Care?

Abstract Reference intervals in clinical chemistry are commonly based on results of measurements in reference populations or are taken from the literature. A reference population should represent a defined group of individuals and be as similar as possible to the patients under investigation. Frequently, reference populations have been recruited from institutionalised healthy young people who do not necessarily fulfill these criteria. In the present study we describe the temporal changes in 37 commonly measured quantities in men and women from childhood to late in life. The samples were collected in the primary health care and sorted according to an assumed decision by the physician. The emerging group of individuals forms a reference population that was regarded as “non-diseased” and the results of measurements in this population are reference values. A remaining group of “non-healthy” were likewise identified for comparison. The central 95 percentile was wider than those usually assigned to the quantities whereas the medians almost coincided. In the “non-healthy” group the medians were shifted in a direction that would be expected from pathophysiology aspects.

The use of error and uncertainty methods in the medical laboratory

Abstract Error methods – compared with uncertainty methods – offer simpler, more intuitive and practical procedures for calculating measurement uncertainty and conducting quality assurance in laboratory medicine. However, uncertainty methods are preferred in other fields of science as reflected by the guide to the expression of uncertainty in measurement. When laboratory results are used for supporting medical diagnoses, the total uncertainty consists only partially of analytical variation. Biological variation, pre- and postanalytical variation all need to be included. Furthermore, all components of the measuring procedure need to be taken into account. Performance specifications for diagnostic tests should include the diagnostic uncertainty of the entire testing process. Uncertainty methods may be particularly useful for this purpose but have yet to show their strength in laboratory medicine. The purpose of this paper is to elucidate the pros and cons of error and uncertainty methods as groundwork for future consensus on their use in practical performance specifications. Error and uncertainty methods are complementary when evaluating measurement data.

Human creatine kinase: Isoenzymes and logistics of energy distribution

A simple procedure to estimate creatine kinase of mitochondrial origin (CK-mit) was tested in homogenates from human myocardial and skeletal muscle. Thereafter CK-mit was estimated as the difference between the activity remaining after immunoinhibition with anit-CK-M and chromatographic isolation of CK-MB. This method was applied to selected human myocardial and skeletal muscle biopsies. These biopsies were selected on the basis of citrate synthetase activity so as to give a large range in oxidative capacity. CK-MB and CK-mit were correlated and both CK-MB and CK-mit correlated to citrate synthetase activity. The isoenzymes CK-MB and CK-mit were thus associated with the oxidative capacity of the tissue. The results confirm the energy shuttle hypothesis for CK with CK-MB located at target organelles.

Can both EDTA and citrate plasma samples be used in measurements of fibrinogen and C-reactive protein concentrations?

Abstract Background: Fibrinogen and C-reactive protein (CRP) concentrations are predictors of outcome in the atherosclerotic patient. It is important in risk stratification that these quantities are measured reproducibly in routine and research. Method: In the present study, we compare measurements of fibrinogen and high-sensitivity CRP in EDTA and citrate plasma samples (n=150) using nephelometric immunoassays. Fibrinogen was also measured in citrate plasma using a clotting method. Results: In approximately one-third of the samples, the fibrinogen concentration measured by immunoassay was higher in citrate plasma than in EDTA plasma, in spite of the dilution by citrate. The immunoassay results of fibrinogen concentration measurements in EDTA and citrate plasma differed significantly and also differed from those of functionally measured fibrinogen concentrations. A difference was found between the concentration of CRP in EDTA plasma and citrated plasma which also did not correspond to the dilution. Conclusions: Reproducibility of results is essential in risk stratification by fibrinogen or high-sensitivity CRP concentrations and small differences close to the decision limits may have a decisive impact. Immunological measurements are liable to confounding effects that may be difficult to foresee, qualitatively and quantitatively. Great care should be observed when measuring the concentration of calcium containing analytes in anticoagulated samples. Fibrinogen concentrations should preferably be measured functionally in citrate plasma. Clin Chem Lab Med 2008;46:1175–9.

Female Urinary Tract Infection in Primary Health Care: Bacteriological and Clinical Characteristics

Female patients with symptoms of urinary tract infection (n = 1136) were studied in primary health care with respect to (a) clinical symptoms as predictors of bacteriuria; (b) relation between aetiological agent and clinical picture, especially for P-fimbriated Escherichia coli; and (c) clinical findings in cases with 10(2)- less than 10(5) CFU/ml of E. coli. Prevalence of bacteriuria (greater than or equal to 10(5) CFU/ml) was 61%. Concurrence of urgency/frequency and dysuria, short duration of symptoms and hematuria increased the probability of bacteriuria and were also significantly more frequent among cases with low counts of E. coli (10(2) less than 10(5) CFU/ml in pure culture or mixed flora) than among cases with sterile urine, indicating an aetiological role of E. coli in many of those cases. Infections with P-fimbriated E. coli were as benign as the P-fimbriae-negative. The rate of P-fimbriation was 29% in specimens containing greater than or equal to 10(5) CFU/ml of E. coli, 30% among specimens with less than 10(5) CFU/ml in pure culture and 10% in specimens containing less than 10(5) CFU/ml of E. coli in mixed culture. Patients infected with Klebsiella, Enterobacter or Proteus did not show a higher rate of previous urinary tract disease or anomalies.