[Nutrition and prostaglandins].
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Animals↗
Biomedical subjects
P Koivistoinen
Publications and source records attributed to P Koivistoinen.
High-performance liquid chromatographic determination of tocopherols and tocotrienols and its application to diets and plasma of Finnish men. I. Analytical method.
A HPLC Method is described for the determination of tocopherols and tocotrienols in human diets and plasma. After a room-temperature saponification diet samples were extracted with n-hexane. A direct hexane extraction was used for plasma samples. Using a normal-phase column at elevated temperature and a fluorescence detector complete separation of all four tocopherols, alpha-, beta-, gamma-tocotrienols and BHA and good reproducibility and sensitivity were obtained. The recovery of tocopherols added to diet samples was 99% for alpha-tocopherol, 95% for beta-tocopherol, 99% for gamma-tocopherol and 80% for delta-tocopherol. The recovery of alpha-tocopherol added into plasma was 99%.
Butylated Hydroxyanisole↗
High-performance liquid chromatographic determination of tocopherols and tocotrienols and its application to diets and plasma of Finnish men. II. Applications.
The composed one-day diets and plasma of 40 Finnish men screened for a selenium supplementation study were analyzed for tocopherols and tocotrienols. The men were divided into a low-Se group (in the screening phase plasma Se levels less than 70 micrograms/l and plasma alpha-tocopherol levels less than 1.2 mg/100 ml) and a high-Se group (plasma Se greater than 70 micrograms/l, plasma alpha-tocopherol not determined before the study). In the low-Se group plasma levels of alpha-tocopherol averaged 0.97 +/- 0.18 mg/100 ml. The daily dietary intake of alpha-tocopherol was 6.1 +/- 2.7 mg and that of total vitamin E 7.3 +/- 3.1 mg of alpha-tocopherol equivalents. In the high-Se group the corresponding average values were 1.16 +/- 0.21 mg of alpha-tocopherol/100 ml of plasma, 8.8 +/- 4.3 mg of alpha-tocopherol/day and 10.3 +/- 5.1 mg of alpha-tocopherol equivalents/day. The overall average for the contribution of alpha-tocopherol to the total dietary tocopherols was 44.6 +/- 11.0%. In the plasma samples alpha-tocopherol accounted for 92.0 +/- 2.1%, beta-tocopherol for 2.7 +/- 0.7% and gamma-tocopherol for 5.3 +/- 2.1% of the total amount of tocopherols.
Canada↗
Determination of chromium in human milk, serum and urine by electrothermal atomic absorption spectrometry without preliminary ashing.
In the present study a Perkin-Elmer 5000 atomic absorption spectrometer equipped with a tungsten--iodide lamp for improved background correction at the 357.9 nm chromium absorption line and an HGA 500 graphite furnace were employed for the direct determination of chromium in human serum, milk and urine. The method of standard additions was used: 0.25-0.75 ng Cr was added to 1 ml samples. Except for urine samples, a dilution of 1 + 1 to 1 + 2 with H2O was necessary in order to obtain correct calibration curves. The average concentration of chromium in all the samples of normal subjects was less than 0.5 ng Cr ml-1. The day-to-day variation for all of the pooled samples was around 10% (relative standard deviation). For urine, the accuracy of the method was tested by comparing the results of another laboratory for the same two round robin samples. Excellent agreement was found between the present method and those of the other laboratory that had used isotope dilution--mass spectrometry and continuum source wavelength modulated echelle--atomic absorption spectrometry to define the chromium concentration in the samples. The detection limit of the method, 0.05 ng Cr ml-1 for urine and serum and 0.1 ng Cr ml-1 for human milk, was sufficient for the biological fluids analyzed. The method was employed for the determination of chromium in 24-h urine samples of maturity onset diabetics supplemented with 20 or 200 micrograms Cr3+ d-1 for six weeks. It was shown that the 24-h urinary chromium excretion accurately indicates the daily dietary chromium intake of these patients.
Adult↗
Bioavailability of selenium to Finnish men as assessed by platelet glutathione peroxidase activity and other blood parameters.
Three groups of 10 men of low selenium status were given 200 micrograms Se/day as Serich wheat, Se-rich yeast, or sodium selenate for 11 wk. Twenty unsupplemented subjects served as controls. Plasma Se levels increased steadily in the wheat and yeast groups for 11 wk without plateauing, whereas in the selenate group, plasma Se plateaued around 110 ng/ml after 4 wk. Platelet glutathione peroxidase (GSH-Px) activities increased rapidly in the wheat and selenate groups for 4 wk and then plateaued. Platelet GSH-Px increased more slowly in the yeast group. Ten weeks after the supplements were discontinued, platelet GSH-Px was higher in the wheat and yeast groups than in the selenate group. Assessment of Se bioavailability requires a short-term platelet GSH-Px measurement to determine immediate availability, a medium-term plasma Se measurement to estimate retention, and a long-term platelet GSH-Px measurement after supplements are discontinued to determine the covertibility of tissue Se stores to biologically active Se.
Adult↗
Effect of heat treatment of dietary fiber: interlaboratory study.
The effects of thermal treatments on the dietary fiber composition of cereal and potato samples were studied at 8 laboratories using different analytical methods. Thermal treatments included extrusion cooking for cereals, and boiling and frying for potatoes. No changes in the amounts of dietary fiber or starch were observed in the extruded samples. Heat-treated potato samples contained significantly more water-insoluble dietary fiber (cellulose) and less starch than did raw potato. However, this may be due, at least in part, to the sample preparation procedure rather than the heat treatment alone. The study indicates that gravimetric and sequential hydrolysis methods give similar results, but the variation in most cases is still wide. Further standardization of methods is evidently needed, especially if legislative measures for setting limits on the fiber content of foods are to be introduced. Standardization of starch analysis should also be of primary importance in future work on carbohydrate methodology. This can be concluded from the variation in results concerning this extremely important food constituent. It should be noted that the sample matrix in the present study was simpler than that of complex meals or diets.
Dietary Fiber↗
Electrothermal atomic absorption spectrometric determination of selenium in foods and diets.
The validity of 2 electrothermal atomic absorption spectrometric methods for determination of selenium in foods and diets was tested. By using 0.5% Ni(II) as a matrix modifier to prevent selenium losses during the ashing step, it was shown that selenium can be determined in samples containing greater than or equal to 1 microgram Se/g dry wt without organic extraction. The mean recovery tested, using NBS Bovine Liver, was 98%; recovery of added inorganic selenium in Bovine Liver matrix was 100%. In addition, this method gave values closest to the median value of all participating laboratories using hydride generation AAS or the spectrofluorometric method in a collaborative study on high selenium wheat, flour, and toast samples. For samples with concentrations less than 1 microgram Se/g dry wt, separation of selenium from interfering Fe and P ions by organic extraction was necessary. Using inorganic 75Se in meat and human milk matrixes, an ammonium pyrrolidine dithiocarbamate-methyl isobutyl ketone-extraction system with added Cu(II) as a matrix modifier yielded the best extraction recoveries, 97 and 98%, respectively. Accuracy and precision of the method were tested using several official and unofficial biological standard materials. The mean accuracy was within 4% of the certified or best values of the standard materials and the day-to-day variation was 9%. The Se/Fe or Se/P interference limits proved to be low enough not to affect selenium determinations in practically all foods or diets. The practical detection limit of the method was 3 ng Se/g dry wt for 1.0 g dry wt samples.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The role of imported grain on the selenium intake of Finnish population in 1941-1981.
When the average intake of selenium among the Finnish population during the period 1941 to 1981 was estimated, the proportion of imported grain used for human consumption, as well as its country of origin, was taken into account as a factor increasing the total intake. The figures indicting the intake of selenium during the study period range from 21 to 56 micrograms/day, clearly exceeding the values obtained when the intake is assessed on the basis of the selenium content of Finnish grain only. The proportion of selenium derived from grain out of the total intake of selenium ranged from 10 to 67% during the study period.
Commerce↗
Strontium in Finnish foods.
The strontium content of Finnish foods was analyzed and the average daily intake of strontium estimated according to national food consumption statistics. The average intake was 1.9 mg of Sr/d/person, which is well within the range of intakes found in other industrialized countries. The most important sources were dairy products (35%), and vegetables and fruits (32%). The strontium contents of foods showed a highly significant correlation with their calcium contents. No special problem was evident in dietary strontium in Finland.
Animals↗
Iodine in Finnish foods.
The iodine content of Finnish foods was analysed and the average daily intake of iodine estimated according to national food consumption statistics. The average calculated intake was 340 micrograms/d/person, although an extensive seasonal variation was found in the estimate for the summer season (280 micrograms) and for the winter season (400 micrograms). The intake is from 4 to 5 times greater now than it was in the mid 1950's, when endemic goitre was common in Finland. The most significant sources of iodine in the average Finnish diet are dairy products, which also cause the seasonal variation in intake. Iodized table salt and eggs are other important sources. The present level of intake can be considered adequate and the further intensification of prohylactic practices with iodine unnecessary.
Animals↗
Annual variations in the average selenium intake in Finland: cereal products and milk as sources of selenium in 1979/80.
Grain, flour and milk samples were collected in spring 1980 and analysed for selenium. The selenium content of flour was approximately 10 times higher than in 1975-1977, and that of milk twice as high. The increase in the selenium content of flour is a reflection of the massive grain imports in 1979/80. The increased selenium level in milk was more unexpected, and may at least partly be due to the increased use of fodders enriched with selenium. The average intake of selenium in 1980 may have been between 50 and 60 micrograms/d/person, while the mid seventies it was found to be substantially lower, about 30 microns/d.
Animals↗
Isolation, purification, and partial chemical characterization of chromium(III) fractions existing in brewer's yeast and Sabouraud's liquid medium.
An ethanol extract of brewer's yeast which had been cultivated in a medium containing trivalent 51Cr was analyzed for 51Cr compounds by using petroleum ether extraction, gel filtration, cation and anion exchange chromatography and thin layer chromatography. Similar analytical procedures as for the above analysis were used for studying 51Cr compounds formed in the spent culture medium and in a sterile medium. Several 51Cr fractions were isolated from the three chromium sources, but one anionic 51Cr fraction present in the yeast and in the spent culture medium was not found in the sterile medium. Molecular weight estimations of the 51Cr fractions by gel filtration chromatography showed that the 51Cr ion exchange fractions contained several 51Cr compounds. The molecular weights of these compounds ranged from 150 to 1000 daltons and the molecular weights of 51Cr compounds separated from the yeast were markedly lower than those of the corresponding ion exchange fractions isolated from the culture medium. By using thin layer chromatography it was possible to isolate 51Cr compounds from the main bulk of ninhydrin active impurities. The polarity of all 51Cr compounds was found to be greater than that of most amino acids. The 51Cr compounds isolated from the yeast were mixed with 125I-insulin and incubated, after which the solution was eluted through Sephadex G-50 gel to test if binding had occurred. Elution peaks of 51Cr and 125I-insulin showed that 51Cr compounds were not bound to the insulin.
Chromium↗
Effects of glucose and chromium(III) concentrations in the medium on the uptake of 51Cr by brewer's yeast.
The incorporation of trivalent chromium into S. carlsbergensis as function of time, the effects of chromium and glucose concentrations in the medium on the uptake of 51Cr by the yeast cells, and the effect of chromium on growth of the yeast were studied. 51Cr was taken up by yeast cells most rapidly during the logarithmic growth period in Sabouraud's liquid medium containing 5% glucose. Cells grown in a medium containing only 0.5% glucose at the beginning of cultivation incorporated very little 51Cr, and incorporation ceased when the glucose concentration was reduced to less than 0.1%. Addition of 5% glucose into this culture resulted in a very rapid increase in the 51Cr uptake. The second glucose addition did not notably increase the rate of 51Cr uptake by the yeast. Chromium, reduced yeast growth slightly, however, was not clearly toxic.
Biological Transport↗
Advances in tin compound analysis with special reference to organotin pesticide residues.
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Colorimetry↗
Bioevaluation of dietary iron in growing rats. V. Response of rats to different levels on meat in a stimulated Finnish diet.
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Anemia, Hypochromic↗
Bioevaluation of dietary iron in growing rats. IV. Response of rats to a simulated Finnish diet with and without iron and copper supplementation.
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Anemia, Hypochromic↗