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O Oster

Publications and source records attributed to O Oster.

30 records · Page 2Linked to original sources
PubMed1982

A methodological comparison of hydride and carbon furnace atomic absorption spectroscopy for the determination of selenium in serum.

Two methods based on different chemical and physical principles for the determination of selenium in serum are elaborated, evaluated and compared--the hydride atomic absorption (AAS) technique and the carbon furnace technique. For the hydride AAS technique a wet destruction method is described. The sensitivity of the method is 10 micrograms Se/1. The carbon furnace technique makes use of the fact that selenium forms refractory selenides when nickel compounds are added. The sensitivity of the carbon furnace technique is 11 micrograms Se/1. The determination of selenium in serum by the hydride AAS and carbon furnace technique correlates satisfactorily (correlation coefficient 0.94; mean value for the hydride AAS 69.1 micrograms Se/1; mean value for the carbon furnace 67.4 micrograms Se/1) indicating that with the carbon furnace technique total selenium (inorganic and organic) is determined. A reference range was established with 99 persons (42 men and 57 women) which show an average selenium content in serum of 80.55 (SD 13.78) micrograms Se/1 [1.02 (0.17) mumol Se/1].

Carbon↗
PubMed1981

The aluminium content of human serum determined by atomic absorption spectroscopy with a graphite furnace.

A method is described for the determination of aluminium in serum by atomic absorption spectroscopy with a graphite furnace. The serum sample is diluted with a diluent of Triton X-100 and HNO3. The dilution enables shorter drying and charring times and a lower charring temperature. The detection limit of the method is 2.5 microgram Al/l serum. Precautions for sample handling are discussed and instrument settings are defined. The direct determination of aluminium in serum is compared with the standard addition method. A good correlation between the two methods was found. Serum from 37 healthy persons was investigated. The serum contained less than 4 microgram Al/l with a range of less than 2.5 microgram to 7 microgram Al/l. The aluminium content of 50 serum samples from hemodialysis patients was determined. The aluminium content of the serum of the hemodialysis patients was in the range of 8 to 713 microgram Al/l. A mean value of 87.7 microgram Al/l (S.D. 122.8) was found.

Aluminum↗
PubMed1981

[The direct determination of mercury in urine by cold vapor atomic absorption spectroscopy (author's transl)].

A method is described for the determination of mercury in urine by atomic absorption spectroscopy. The organically bound mercury is oxidized by treatment of the urine with KMnO4, followed by dilution with a mixture of HNO3 and H2SO4. The sample is then treated with NaBH4 to release the mercury vapor. This procedure measures total mercury (inorganic and organically bound) in the urine. The method was compared with the standard addition method and with the determination after wet digestion with concentrated HNO3. A good correlation was found between the three methods. Other organic and inorganic compounds present in urine do not interfere. Using 1 ml urine samples, the detection limit is 2 micrograms/l Hg. Sensitivity is also 2 micrograms/l Hg. Urinary mercury in a non-exposed population (30 men, 30 women) was found to be less than 4 micrograms/l Hg.

Adult↗
PubMed1975

Deuterium nuclear magnetic resonance of deuterium-labeled diacetyldeuterohemin incorporated into sperm whale myoglobin.

The heme derivative 2,4-diacetyldeuterohemin deuterated in the methyl groups of the acetyl moieties was reconstituted with sperm whale apomyoglobin and the two labeled methyl groups in the protein environment were observed by deuterium nuclear magnetic resonance spectroscopy. The results were compared to the free hemin form as the dimethyl ester in chloroform and in a pyridine-water mixture, as well as in the zinc complex form. Under most conditions the two methyl resonances overlie each other to a large degree. Resonance width at half-height is of the order of 25 Hz for the protein and approximately one-third as much for the free hemin at 16 degrees and is little affected by conversion to paramagnetic derivatives. Chemical shifts for the oxy- and carbonmonoxymyoglobins are very similar. In cyanoferrimyoglobin a positive pseudo-contact contribution of 3.04 ppm was computed to explain a relative upfield shift offset in part by a small negative contact shift contribution. The cyanoferrimyoglobin resonance was sensitive to the presence of phosphate buffer as well as to cyclopropane. The aquoferrimyoglobin form shows distinct resonances for the two methyl groups, with the downfield resonance considerably broadened. The expected effects of temperature on chemical shift were observed, the paramagnetic derivatives showing an effect and carbonmonoxymyoglobin showing none. The relaxation behavior was gauged from the line widths and from measurements of spin-lattice relaxation time, T1. The effective rotational correlation time is of the order of 50 ps for the liganded myoglobin forms. The temperature dependence of the line widths may imply an increased retational freedom with increasing temperature. The broadening observed in the aquoferrimyoglobin case is indicative of restricted internal rotational motion of one of the methyl groups. The method is suitable for probing the more mobile structures in proteins and retains its value in the neighborhood of paramagnetic centers.

Animals↗
PubMedDate not supplied

The daily dietary selenium intake of West German adults.

The selenium content of food consumed in the Federal Republic of Germany (FRG) was determined for the estimation of the dietary selenium intake of West German adults. The daily dietary selenium intake of men is 47 micrograms (micrograms) and that of women 38 micrograms, corresponding to 0.67 microgram/kg body weight per day for both men and women. Animal protein is the main source of dietary selenium, accounting for 65.5% of the total selenium intake. Pork contributes 25.1% to the total Se intake, reflecting the current consumption and the selenium supplementation of feedstock rather than the availability of selenium from natural dietary sources. The selenium intake of adults in West Germany is only slightly higher than in New Zealand, Finland, and Italy, nearly equal to that in Belgium and France, and distinctly lower than in Great Britain, the USA, Canada, and Japan.

Adult↗
PubMedDate not supplied

The organ distribution of selenium in German adults.

The selenium concentrations were determined in liver, kidney, skeletal muscle, heart, brain, prostate, testis, bile, lung, and spleen of German traffic accident victims. In addition, the nitrogen and phosphorus contents were determined in the same organs and tissues. On a per-weight unit basis, the highest selenium concentration was found in kidney. However, this corresponds to only 4% of the total body selenium. Most of the whole body selenium (50%) is present in skeletal muscle, which thus appears to act as a selenium storage organ. However, there is also evidence that selenium is required for muscle function. In plasma and interstitial fluid, .450 mg of Se, or 7.5% of the total body selenium is present. A comparison of the organ Se concentrations of the German traffic accident victims with the selenium concentrations of the same human organs as reported in different countries indicates that the organ concentrations of West Germans are comparable to that of the population of New Zealand, a low-Se country, and significantly lower than that observed in the organs of American, Canadian, and especially Japanese subjects. The international comparison of the organ selenium concentrations also revealed that the selenium uptake of kidney is higher at low- and adequate dietary Se intakes and lower if the dietary Se supply is high, as is the case for Japanese subjects. Estimates of the daily excretion of selenium with the bile indicate that the amounts are three times higher than the daily urinary losses and in the same order of magnitude as the daily dietary selenium intakes. Enterohepatic reabsorption of selenium from the bile appears to be a significant mechanism of conserving dietary selenium and to maintain Se balance at comparatively low dietary Se intakes.

Adult↗
PubMedDate not supplied

Correlations of blood selenium with hematological parameters in West German adults.

The serum selenium and the whole blood selenium of 72 healthy persons (47 women, 25 men) was determined. There exist sex specific differences of the whole blood selenium between men (98 +/- 19 micrograms Se/L) and women (89 +/- 17 micrograms Se/L). The serum selenium did not show sex specific differences, but sex specific differences are found if the total amount of extracellular selenium is calculated by correction of the serum selenium with the hematocrit. Women have more extra-cellular selenium/L whole blood (40 +/- 8 micrograms Se) than men (36 +/- 7 micrograms Se). Men have more intraerythrocyte selenium (cellular selenium = 67 +/- 14 micrograms Se) in one L whole blood than women (52 +/- 17 micrograms Se). There exist also sex specific differences if the cellular selenium is calculated/g hemoglobin (men .44 micrograms Se/g Hb, women .37 micrograms Se/Hb) or per erythrocyte (men 136.1 x 10(-19) g Se/Ery, women 113.9 x 10(-19) g Se/Ery). In the cellular compartment of one L whole blood on the average 1.56 times more selenium is present than in the extracellular compartment. Most of the intraerythrocyte selenium is hemoglobin bound (84%) and utmost 16% glutathione peroxidase associated. An erythrocyte contains about 3500 mol glutathione peroxidase, or, for every 80000 mol hemoglobin one mol glutathione peroxidase. A standard man needs about 2.5 micrograms selenium/d for the synthesis of the hemoglobin and the erythrocyte. The hematological parameters hemoglobin and the erythrocyte number are correlated with the cellular selenium and the ratio cellular selenium/extracellular selenium. Positive significant correlations are found that are best if a parabolic model is used to interpret the shape of the curves. From the shape of the best correlation lines it can be concluded that selenium may be beneficial for hemoglobin synthesis and erythropoesis. The extracellular selenium may have influence on the volume of the erythrocyte by protecting the outer erythrocyte membrane from lipid peroxidation. A method is reported based on the carbon furnace atomic absorption spectroscopy, which is able to determine without wet digestion selenium in whole blood.

Adult↗
PubMedDate not supplied

The arsenic content of human semen.

Arsenic concentration was measured by atomic absorption spectrometer in ejaculates of 13 subfertile men, 6 control individuals and pool-ejaculate of 24 further andrological patients. While the detection limit was 1 microgram/l, arsenic concentration amounted to 2 micrograms AS/l in ejaculates. In the cellular fractions of seminal fluid, concentration of arsenic was under the detection limit. Arsenic concentration of smokers and non-smokers did not differ.

Adult↗
PubMedDate not supplied

Increase in proto-oncogene raf expression precedes differentiation induction in different clonal rhabdomyosarcoma subpopulations.

Three clonal rat rhabdomyosarcoma subpopulations (A, B, C) with a block of differentiation at different levels of rhabdomyogenesis were exposed to the differentiation inducers retinoic acid (RA), N-methylformamide (NMF) and sodium butyrate (NaBut). Since an increased expression of c-raf and c-fos had recently been demonstrated for subpopulation C after exposure to RA and NMF (1), the mRNA expression of c-raf, c-fos and retinoic acid receptor (RAR) alpha, beta and gamma was compared in all three subpopulations. After exposure to RA, NMF or NaBut, subpopulation C exhibited a significant (p = 0.0001) increase in creatine kinase (CK) activity and in morphological differentiation. In subpopulation B, the response was confined to a significant (p = 0.0001) increase in creatine kinase activity, whereas subpopulation A proved to be differentiation-refractory. On the molecular level, a uniform increase in c-raf expression became evident in all three subpopulations after 6 to 12 hours, persisting at an elevated level throughout the observation period of 120 hours. In contrast, the pattern of c-fos expression observed after exposure to RA, NMF or NaBut was heterogeneous. Expression of RAR alpha and gamma was detected in all subpopulations, whereas RAR beta mRNA was not expressed. Summarizing our results, the uniform pattern of c-raf expression might suggest a participation of c-raf in differentiation signal transduction. Since the three subpopulations differ markedly in their degree of differentiation, the block of differentiation characteristic for each subpopulation supposedly becomes effective only after the action of the c-raf gene product.

Animals↗
PubMedDate not supplied

Purification of histone F3 by covalent chromatography.

The arginine-rich histone F3 has been purified by covalent affinity chromatography. By the use of activated Thiol-Sepharose 4B for the purification of cysteine containing histone F3 a highly purified protein was obtained. The simple purification procedure offers the opportunity to get larger amounts of pure histone F3 within short time.

Animals↗