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Biomedical subjects

M Schmidt

Publications and source records attributed to M Schmidt.

At least 865 records · Page 48Linked to original sources
PubMed1982

Variance comparison as a tool in clinical pharmacology: an example with two loop diuretics.

Comparison of variances can be usefUl in assessing the regularity of drug effects. In order to compare the variances of the saluretic effects of piretanide and frusemide, two loop diuretics with different bioavailabilities, a double-blind cross-over study was carried out in 34 normal volunteers. The diuretics were given in randomized order, with an interval of 7 days, in single equipotent doses (frusemide 6.25 mg and piretanide 1.0 mg chosen from previous results) adjusted by body weight. The dispersion of individual values (comparison of variances from paired measures) for Na+, Cl- and Ca++ excretion, urine osmolality and excretion of the drugs, was significantly smaller for piretanide than for frusemide. It is concluded that the saluretic effect of a single dose of piretanide varies less than that of an equipotent dose of frusemide. The methodology may be useful in trials of drugs for which regularity of effect is important.

Biological Availability↗
PubMed1982

[Indirect breast lymphography (author's transl)].

Intradermal areolar contrast injection of a new water-soluble contrast medium, Iotasul, results in regular demonstration of the latero-cranial breast lymphatics and of the subareolar lymphatic plexus. It has been possible, for the first time, to show lymph nodes with this water-soluble contrast medium, although the results are not entirely satisfactory. There have been no side effects.

Breast Neoplasms↗
PubMed1982

Comparison of radioimmunoassay, chemical assay (HPLC) and bioassay for arginine vasopressin in synthetic standards and posterior pituitary tissue.

Radioimmunoassay and chemical assay (high performance liquid chromatography (HPLC) with fluorescence detection) for arginine vasopressin (AVP) in purified synthetic preparations and in posterior lobe tissue samples (ox and rat) yielded essentially identical values. In tissue samples from the neurohypophysis, the reproducibility of the former method was roughly twice as good. The routinely used blood pressure bioassay was very poorly reproducible and yielded values deviating from the two ther methods. In all three assays, the coefficient of variation was roughly five times higher in tissue samples than in synthetic preparations. It is suggested that a chemical rather than a biological assay is used for standardization of AVP for radioimmunoassay. Large differences were found in the quality of AVP preparations potentially usable as standards and tracers (after iodination) for radioimmunoassay. All commercial preparations should therefore be checked for their AVP and impurity content by high performance liquid chromatography.

Amino Acids↗
PubMed1982

[Direct determination of free thyroxine in two simultaneous radioimmunoassays with different test principles: validity of test research derived from an area of marked iodine deficiency (author's transl)].

Serum FT4 was measured simultaneously by the commercial FT4 kits of Amersham-Buchler and Corning Medical in 4 groups with defined thyroid function as follows: 57 euthyroid subjects with and without goitre, 27 patients on T4 supplementation, 12 subjects on oral contraceptives and 26 subclinically hyperthyroid patients. All patients underwent physical examination, thyroid scintigraphy and additional in-vitro tests (total thyroxine T4, total triiodothyronine T3 and TRH/TSH assay). Both assays generally correlated well with the defined thyroid functional status except for the patients on oral contraceptives. Contrary to the FT4-test (Amersham-Buchler) in this group the FT4-test (Corning Medical) produced a significantly increased mean for FT4 as compared to the euthyroid groups thus indicating a probably insufficient compensation for high but not necessarily abnormal levels of TBG concentration. Using the FT4-assay (Amersham-Buchler) the normal range of FT4 values of euthyroid subjects from the area of Bamberg with marked iodine deficiency agrees well with recently published results of a multicentre trial thus confirming the assumption of serum FT4 not being strongly dependent on iodine intake. The results of the FT4-test (Corning) showed a wider scatter of normal ranges of FT4 values for all groups and concomitantly reduced discrimination compared to the corresponding simultaneously obtained FT4-test (Amersham-Buchler) results. Though cost and time saving, the commercial radioimmunoassays will require further critical evaluation of normal range validity on larger populations of defined abnormalities of thyroid function to elucidate inherent deficiencies of the new FT4 methods and of their diagnostic efficiency.

Contraceptives, Oral↗
PubMed1981

Exaggerated cyclic AMP accumulation and glial cell reaction in the cerebellum during Purkinje cell degeneration in pcd mutant mice.

The Purkinje cell degeneration mutant (pcd) is characterized by a complete loss of cerebellar Purkinje cells. Norepinephrine causes an accumulation of cyclic AMP in the cerebellum of pcd that is far greater than in normal mice. Experiments were conducted 1) to correlated changes in the cyclic-nucleotide response with a histologic examination of the cerebellum during neuronal loss and 2) to examine the role of cyclic AMP catabolism and adenosine receptor interactions in the phenomenon. The greatest elevation in cyclic AMP occurred between 30 and 128 days of age when a severe astrocytic response was demonstrated throughout the cerebellar cortex. Purkinje cells had degenerated by 45 days of age. Norepinephrine elicited a smaller increase in cyclic AMP from 155-day-old mice than at earlier ages, and the response continued to decrease with age; at 270 days, equal accumulation, and at 365 days. lower accumulation of cyclic AMP was detected in pcd cerebella. During this time, the Purkinje cell debris had been removed, the granule cell layer was depleted of granule cells, and the molecular layer was deprived of a large number of parallel fibers. However, although phagocytosis of neuronal debris was completed, large numbers of astrocytic processes were still seen in the neuropil. Biochemical experiments in vitro established that the exaggerated accumulation of cyclic AMP in the presence of norepinephrine was not due to lower catabolism of cyclic AMP, a synergistic interaction with adenosine, or a result of lower protein in the pcd cerebellum. The correlates of heightened norepinephrine-stimulated accumulation of cyclic AMP with neuronal loss and the glial cell reaction might indicate that cyclic nucleotides play a role in controlling some glial cell functions, ie, proliferation, migration, and phagocytosis.

Animals↗