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D Hötzel

Publications and source records attributed to D Hötzel.

At least 37 records · Page 2Linked to original sources
PubMed1982

[Methods and their evaluation in estimating the vitamin B6-status in humans. 3. Determination- of 4-pyridoxic acid in urine].

A method based on the fluorimetric determination of the 4-PA-lactone is described. The applied method saves time and work compared to others. The analytical procedure may be interrupted for a few days after eluting the 4-PA from the ion exchanger as well as before measuring the transmission. Accuracy, precision and sensitivity of the method are demonstrated. Interfering substances influencing the fluorescence measurement and probable errors caused by the reference value creatinine are discussed. Storage tests applied with the urine samples at--18 degrees C have shown that 4-PA-values do not change considerably within two months.

Chromatography, Ion Exchange↗
PubMed1982

[Methods and their evaluation in estimating the vitamin B6-status in humans. 4. 4-PA: reliability of the parameters].

Effects of physiological factors on 4-PA-excretion of more than 400 industrial workers and students were examined. Borderline values are discussed. With increasing age men as well as women showed significant higher 4-PA-values. After optimizing the vitamin B6-uptake by means of vitamin administration the differences disappear. Age-depending variations in the ability forming 4-PA are not likely. The higher 4-PA-excretion of men is probably due to better dietary supply rather than to sex differences in metabolising the vitamin. There are no considerable influences on the parameter by oral contraceptives Short-term variations of dietary vitamin B6-supply have striking effects on the 4-PA-excretion and restrict the reliability of this parameter. An insufficient vitamin B2-supply can stimulate a marginal vitamin B6-status. Alcohol consumption the day before does not change the 4-PA-excretion.

Adult↗
PubMed1981

[Evaluation of methods to determine the vitamin B6 status of humans. 1. alpha-EGOT: methods and validation].

A semiautomatic method to determine the activation coefficient of the glutamic-oxaloacetic-transaminase in the erythrocytes is described. This method is compared with other methods and possible sources of error are discussed. Colorimetric methods show considerable disadvantages, such as lack of precision or unspecific hydrazone formation. The kinetic tests avoid these problems. This is in part due to the fact that enzyme stimulation by excessive PLP-addition as used in our procedure bears practical and theoretical advantages. Nevertheless, comparison with published data on vitamin B6 status remains difficult because of insufficient standardization of the used methods. To validate our method we performed experiments testing the stability of the samples, short-term physiological changes and influence of the chelating agent EDTA on transamination. Heparinised blood samples can be stored only for one day with changing at 4 degrees C or room temperature. Storing of the erythrocytic suspension at deep-freezing temperature (-18 degrees C) leads to considerable changes of results. When kept under liquid nitrogen there is no change of the alpha-values for at least 45 days. The addition of EDTA to the samples is known to exclude the influences of cations, such as non enzymatic transamination of a direct alteration of the enzyme activity and therefore EDTA should be added to improve standardisation of the method. The described procedure is a fast, reliable and precise way to determine the alpha-EGOT.

Aspartate Aminotransferases↗
PubMed1981

[Radiological investigations of cobalamin supply with regard to folate status (author's transl)].

In a study with 307 volunteers we estimated the cobalamin status by radiochemical (plasma cobalamin) and haematological (lobe average of granulocytes) methods. As there is a close biochemical connection between the folate and cobalamin metabolism (methyl-tetrahydrofolate-trap hypothesis) we additionally determined the plasma- and erythrocyte folate levels in 307 volunteers by radioimmunoassay. Further metabolic studies in humans showed that a cobalamin concentration of less than 160 pg/ml indicates a deficient supply. In the present study 6% of the men and 8% of the women showed an inadequate alimentary supply.

Erythrocytes↗
PubMed1980

[Investigation or oral substitution of iron and folic acid (author's transl)].

In a study of apparently healthy volunteers (5 male, 5 female) the bioavailability of iron and folacin was calculated using Tardyferon¿ resp. Tardyferon-Fol¿ as test substances. Blood samples for serum iron and folacin level determinations were obtained before and 1/2, 1, 2, 4, 6 and 8 hours after dosing. Because of the diurnal fluctuation of serum iron and folate levels, baseline levels were obtained at the corresponding 0, 1/2, 1, 2, 4, 6 and 8 hours one week prior to the study. Serum iron and folacin levels above the baseline values and the area under the curve were calculated. The data suggested a good bioavailability of the tested substances. The folacin absorption after a single dose of 0.35 mg produced a maximal serum concentration of mean = 28 ng/ml. Twice the dose resulted in a maximum of serum folacin level of mean = 51 ng/ml. The oral administration of 80 mg Fe2+ resp. 160 mg Fe2+ resulted in a significant increase of the serum iron levels, too.

Administration, Oral↗
PubMed1980

[Biochemical and hematological parameters for the estimation of folate status in man. 3. Importance of formiminoglutamic acid excretion in the urine in comparison to other measurements].

In a study on 250 industrial workers the amount of the formiminoglutamic acid excretion in urine was measured by an enzymatic spectrophotometric method. For the estimation of the folacine status the vitamine concentration in serum and erythrozytes was determined as well as the segmentation of the neutrophilic granulocytes. As shown in previous studies these parameters indicate the degree of folate supply. A correlation between the FIGLU excretion in urine and other folate dependent parameters could not be demonstrated. Criterial to judge the folate supply are the radioimmunological determination of folacine concentration in serum and erythrocytes as well as the estimation of the segmentation of the neutrophilic granulocytes.

Female↗
PubMed1978

[Biochemical and hematological measures for determination of folate status in humans. 1. Relation between serum folate and segmentation of neutrophil granulocytes].

In a study on 130 student volunteers the segmentation of neutrophil granulocytes was measured. The serum folate concentration was used as biochemical reference. Both parameters indicate the state of folate supply or the degree of folate deficiency, respectively. Considering the haematologic response as an objective criterion only 71% of the examines showed an adequate folate status. 11% were found "deficient" and 18% were in a marginal state of folate supply. This result was confirmed by repeating the experiment. Further studies are to include folate concentration of erythrocytes and urine concentration of formiminoglutamic acid.

Adult↗
PubMed1978

[Biochemical and hematological measures for determination of folate status in humans. 2. Comparative determination of folate in blood and in erythrocytes].

Criteria to judge the folate supply have been evaluated in previous studies. The present study is examining parameters to estimate the degree of folate deficiency. Serum folate levels and erythrocyte folate concentrations were measured in 116 volunteers (patients). The erythrocyte folate is to a large extend independent of exterior supply and is lowered only in severe chronic deficiency. Low levels of erythrocyte folate indicate longstanding undersupply. Our experiments show that folate concentration of greater than 250 ng per ml erythrocytes indicate adequate supply. Concentrations below this limit are characteristic for chronic folate deficiency. To confirm this statement further studies will take into account the urine concentration of formiminoglutamic acid.

Adult↗
PubMed1977

[Thin layer chromatography of riboflavin in urine (author's transl)].

A method is described for determining riboflavin excretion in urine by thin-Layer chromatography. The sample will be preliminarily purified on Permutit T with subsequent separation of riboflavin by thin-layer chromatography on Kieselgel HR with pyridine--acetic acid--water as an eluant. Substances interfering with the fluorescence of riboflavin can be eliminated through the procedure. Riboflavin remission is measured by a chromatogram-spectralphotometer with fluorescence equipment. Between 0.02 to 0.5 mug riboflavin intensity of fluorescence is proportional to the concentration of riboflavin.

Chromatography, Thin Layer↗
PubMed1977

[Biotin supply and pyruvate carboxylase in blood (author's transl)].

Assaying the activation of pyruvate carboxylase in erythrocytes by measuring the enzyme activity before and after addition of biotin and ATP to the reaction mixture enables to estimate the biotin supply in vitro. According to this method in biotin deficient rats the pyruvate carboxylase-activity increased to 70%, while the increase of activity in supplemented animals amounted to 16%.

Animals↗