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Biomedical subjects

M G Woldring

Publications and source records attributed to M G Woldring.

At least 55 records · Page 3Linked to original sources
PubMed1977

Reevaluation of triethers as markers for triglycerides during gastric emptying.

The validity of using triethers as markers for triglycerides during gastric emptying was investigated. Rats were given a lipid mixture containing [75Se]triether plus [131I]triolein or [3H]triether plus [14C]triolein intragastrically. Similar studies were performed on humans using a homogenized test meal to which was added [75Se]triether plus corn oil. Analysis of gastric contents at various time intervals after administration of the test meal did not show evidence of separation of triglyceride and triether in the stomach. It is discussed that the disappointing results of other workers using [3H]triether may be due to an artifact associated with instability of the tritium-to-triether bond in the preparation used.

Animals↗
PubMed1977

Estimation of fat absorption from single fecal specimens using 131I-triolein and 75Se-triether. A study in rats with and without induced steatorrhea.

The simultaneous use of 131I-triolein and 75Se-triether, a nonabsorbable marker, in a single oral dose to estimate fat absorption from incomplete fecal collections was tested in rats with and without induced steatorrhea. The results in normal rats showed that analysis of single stool samples allows a valid estimate of fat absorption as defined by the balance study based on the total fecal recovery of 131I. However, in the few normal rats with poor absorption, the absorption values from successively excreted stools showed a tendency to increase. Similar findings were obtained from biliary fistula rats with marked steatorrhea. No evidence of different intestinal transit rates of test fat and marker was observed in bile-diverted rats, thus suggesting that the observed inconsistency in fat absorption values from different stool specimens reflects intraprandial differences in the absorption of fat. Studies on rats subjected to intestinal ischemia do not support the suggestion of others that separation of fat and triether will occur if a mucosal defect is involved as the cause of fat malabsorption. It is concluded that this dual isotope technique may be of value in the clinical estimation of fat absorption, as it offers important technical advantages over conventional fat balance studies.

Animals↗
PubMed1976

Specificity of immunoassays. I. Effect of plasma proteins on the specificity of steroid immunoassay.

The theory of the measurement of the specificity of antigen binding by antibodies is reviewed. The specificity of steroid immunoassay has been investigated using a new solid phase radioimmunoassay system. The effects of plasma proteins on the specificity of the immunoassays have been tested. The methods used and the conclusions reached have been tested with homogeneous antibodies in order to simplify the interpretation of the results obtained. A new criterium of antibody homogeneity is proposed. The importance of correcting all results accurately for "non-specific binding" is emphasised. A new method for plotting radioimmunoassay standard curves is presented.

Aldosterone↗
PubMed1976

Cobalt-57-bleomycin scanning of hila and mediastinum in patients with bronchial carcinoma: a prospective study.

Because the results with cobalt-57-bleomycin (57Co-bleo) as a tumour-seeking agent in patients with pulmonary tumours were promising, a prospective study was carried out to test the sensitivity and selectivity of this technique for metastases in lung hila and mediastinum in a group of patients with bronchial cancer. The sensitivity of 57Co-bleo scintigraphy appeared to be higher than that of routine radiological investigations and mediastinoscopy. For this reason it is suggested that 57Co-bleo scintigraphy can be used as a method to select patients for mediastinoscopy.

Adult↗
PubMed1976

Labelling of bleomycin with cobalt-57, indium-111, technetium-99m, mercury-197, lead-203, and copper-67.

The radiochemical purity of the cobalt-57 complex of bleomycin could be enhanced by adjusting the pH of the final product to a value between 5 and 6. This radiopharmaceutical appeared to have better tumor visualizing properties compared to the not neutralized preparation. The clinical use of the cobalt-57 bleomycin complex is however limited by the long physical half-life of the label, causing a risk of radioactive contamination. It appeared to be possible to label bleomycin with radioactive cations (111In3+, 99mTc4+, 197Hg2+ and 67Cu2+) having suitable gamma ray energies and short half-lifes. These bleomycin complexes showed a high radio-chemical purity judged by their behaviour on thin layer chromatography, paper chromatography, and electrophoresis, but their application as tumor visualizing radiopharmaceutical turned out to be disappointing compared with cobalt-57 bleomycin.

Bleomycin↗
PubMed1975

Evaluation of carbon-11 labelled phenylglycine and phenylalanine for pancreas scintigraphy.

Carbon-11 (t1/2 equals 20.4 min, beta-+) labelled DL-alpha-phenylalanine and DL-alpha-phenylglycine were administered intravenously to rats and the distribution of the radioactive amino acids over pancreas, liver, spleen, kidneys and blood was measured after several time intervals. From these results the ratios of the concentration in pancreas and liver were calculated and compared with the corresponding ratios from the literature for some 18-F-labelled aromatic amino acids and L-selenomethionine-75-Se. On the basis of this study it appears that DL-alpha-phenylglycine-1-11-C, in spite of a small percentage of the administered dose reaching the pancreas, and DL-alpha-phenylalanine-1-11-C are better suited to pancreas scintigraphy than L-selenomethionine-75-Se.

Animals↗
PubMed1975

Estimation of plasma testosterone without extraction and chromatography.

A new radioimmunoassay for plasma testosterone in human blood plasma is described. The assay is performed directly upon the plasma without extraction and purification of the testosterone. Antibodies to testosterone-7alpha-carboxyethyl thioether-bovine serum albumin are used and data concerning the specificity of these antibodies are given.

Animals↗
PubMed1975

A new cocktail for liquid scintillation counting of aqueous radioimmunoassay-samples.

The aim of this investigation was to find a scintillation mixture for counting up to 1 ml of plasma. We succeeded in obtaining a mixture of xylene/Triton X-100/mono- and di-butylphosphate, and called it Plasmasol. The properties were ideal for radioimmunoassays of steroids. Good dissolving properties, high counting efficiency, absence of chemiluminescence and a good stability and reproducibility with respect to the disintegrations per minute were achieved. The cost was only 25% of the commercially available ready-to-use liquid scintillation mixtures, with which a comparison was made.

Blood↗