The Nordic Trueness Project 2002: use of reference measurement procedure values in a general clinical chemistry survey.

Up to 136 laboratories participated in a joint effort to assess the trueness of routine measurements for 14 serum components. An unmodified, fresh-frozen human serum ("IMEP-17 Material 1"), produced for an international inter-laboratory comparison, served as the "master material". The serum had assigned values of the highest available metrological quality, and is assumed to involve no or negligible commutability problems. The material was used in the assignment of traceable values to two other reference sera, "CAL" and "X", through parallel measurements on the three materials according to a common protocol. In this transfer process, uncertainty estimates were provided for all values. The material CAL had been supplied with reference measurement procedure values in 1997, and the two sets of assigned values agreed well. A lyophilized control serum "HK02" was also included in the routine analysis series. It, too, had assigned values based on reference measurement procedures. Significant matrix effects were found. The project has provided: Assigned traceable values for 14 components in a fresh-frozen serum, available to Nordic laboratories for the coming years as "NFKK reference serum X"; Confirmation of earlier assigned reference measurement procedure values for a number of components in CAL, the main calibrator in the Nordic Reference Interval project (NORIP). The transferred values will now serve as the primary reference.; Evidence of long-term stability ( > or = 5 years) of the fresh-frozen serum CAL when stored at -80 degrees C; Evidence of substantial matrix effects in the processed serum HK02. The findings should be used to discuss to what extent reference measurement procedure values are useful and cost-efficient for this type of material.

Anti-oxidant supplementation decreases TBA reactants in serum of elderly.

An "anti-oxidant cocktail" consisting of betacarotene, vitamins B6, C, E, zinc, and selenium or corresponding placebos were given for one y as daily dietary supplements to 45 elderly residents of a nursing home. Initially, the serum TBA reactant levels were higher (2.7 +/- 0.7 mumol/L) than those of an ad hoc control group of healthy younger adults (2.3 +/- 0.6 mumol/L), p less than 0.01. After three mo supplementation, the levels among the verum elderly had decreased to 2.2 +/- 0.6 mumol/L, and they remained at this lower level until the end of the study period, whereas the placebo group showed no change. A significant inverse correlation (r = -0.428, p less than 0.01) existed between the concentrations of serum TBA reactants and whole blood selenium (B-Se), but only B-Se levels above 200 micrograms/L were associated with a decrease in serum lipid peroxides. Serum alpha-tocopherol concentration also correlated inversely with serum TBA reactants but this correlation (r = -0.273, p less than 0.76) was not as strong as that of B-Se. Deficient vitamin B6 status, in biochemical terms, was observed in 25% of the elderly; a daily supplement of 2 mg B6 fully cured all cases of deficiency. The verum group improved slightly in several psychological tests, whereas subjects on placebo remained unchanged or deteriorated during the follow-up period. Clinical amelioration among the verum subjects was reported by the nurses; no toxic side effects were reported. In conclusion, the elderly benefited biochemically and clinically of dietary antioxidant supplements.

Erythrocyte glutathione peroxidase and superoxide dismutase in Alzheimer's disease and other dementias.

Activities of 2 enzymes protecting from free radical damage, erythrocyte glutathione peroxidase and superoxide dismutase, were measured in 4 patients with Alzheimer's disease, in 4 with multi-infarct dementia, in 1 with Huntington's disease and in 1 with Hakola-Nasu disease. In none of these dementing diseases the activities were diminished compared to controls.