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Biomedical subjects

H Breuer

Publications and source records attributed to H Breuer.

At least 91 records · Page 5Linked to original sources
PubMed1982

LH pattern in ovariectomised rats after continuous blood withdrawal: effects of different substitutions.

Plasma concentrations of LH and of sodium, potassium, total protein and haemoglobin were measured in ovariectomised rats during continuous blood withdrawal up to 180 min; 0.45 ml blood samples were taken every 10 min, the total volume of blood removed not exceeding 9 ml. Four groups of animals were studied: group A received no substitution (controls), group B was substituted with 0.9% NaCl-solution, group C with 3.5% polypeptide solution (Haemaccel), and group D with a suspension of washed erythrocytes from the blood removed. During blood withdrawal, the mean values of LH concentrations as well as the amplitudes of the rhythmic LH pulses remained constant in all the animals. However, the rate of pulses was reduced in the control animals and in the group receiving 0.9% NaCl-solution during the period between 90 and 180 min; in contrast no change was observed in the groups C and D during the whole period. The results presented here show that the characteristic LH pattern in ovariectomised rats is not affected by volume depletion, provided the blood is replaced by a solution containing either a polypeptide or a suspension of washed erythrocytes.

Animals↗
PubMed1982

Simultaneous perfusion of [4-14C]oestriol and [6,9-3H2]oestriol 16 alpha-monoglucuronide through the isolated rat liver. I. Qualitative aspects.

Equimolar concentrations of [4-14C]oestriol and [6,9-3H]oestriol 16 alpha-monoglucuronide were simultaneously perfused through isolated rat livers. Oestriol was hydroxylated to 2-hydroxyoestriol and 6 xi-hydroxyoestriol; 2-hydroxyoestriol was further methylated to 2-methoxyoestriol. Oxidoreduction of oestriol led to the formation of 16 alpha-hydroxyoestrone, 16-0xooestradio-17 beta and 16-epioestriol. In addition, two dehydroxylation products, namely oestrone and oestradiol-17 beta were found. The metabolites formed from oestriol were partly conjugated to monoglucuronides, monosulphates and sulphoglucuronides. About 80% of the oestriol perfused was hydroxylated at C-atom 2. Most of the 2-hydroxyoestriol formed was either methylated (about 37%) or sulphated (about 55%). Only small amounts (less than 2%) of the catecholoestrogens formed were methylated as well as sulphated. The 2-hydroxyoestriol monosulphates accumulated in the liver. After their conjugation with glucuronic acid, the double conjugates formed were immediately excreted into the bile. In fact, 2-hydroxyoestriol 16 alpha-monoglucuronide 2(3?)-monosulphate comprised by far the main biliary metabolite of [4-14C]oestriol, followed by oestriol 16 alpha-monoglucuronide and 2-methoxyoestriol 16 alpha-monoglucuronide. No triated sulphoglucuronides were detected, thus indicating that the monosulphates are the immediate precursors of the double conjugates. [6,9-3H2]Oestriol 16 alpha-monoglucuronide was metabolised only to a small extent. After its uptake into the liver more than 90% of this conjugate was secreted unchanged into the bile. The remaining part was hydrolysed; the oestriol liberated followed the same metabolic reactions as those found for [4-14C]oestriol. This indicates that the 16 alpha-glucuronide of oestriol is not metabolised to any appreciable extent.

Animals↗
PubMed1982

Simultaneous perfusion of [4-14C]oestriol and [6,9-3H2]oestriol 16 alpha-monoglucuronide through the isolated rat liver. II. Kinetic aspects.

The uptake of [4-14C]oestriol by the isolated perfused rat liver is 3.8 times faster as compared to that of simultaneously perfused [6,9-3H2]oestriol 16 alpha-monoglucuronide. During perfusion the concentration of both radioactive oestrogens decreased exponentially in perfusion medium (apparent kel: 0.061 min-1 and 0.016 min-1, respectively). [6,9-3H2]Oestriol 16 alpha-monoglucuronide was metabolized only to a small extent; more than 92% was secreted unchanged into the bile where it was highly concentrated (1800 nmol/g). In contrast [4-14C]oestriol was extensively metabolized; it was mainly hydroxylated at C-atom 2, leading to a rapid increase in the concentration of 2-hydroxyoestriol in the perfused medium. This metabolite was quickly taken up by the liver during recirculation and subsequently either methylated or sulphated. 2-Hydroxyoestriol monosulphate was glucuronated to 2-hydroxyoestriol 16 alpha-monoglucuronide 3-sulphate, which was rapidly excreted into the bile. No double conjugate was formed when [6,9-3H2]oestriol 16 alpha-monoglucuronide was perfused; this is additional evidence for the correctness of the assumption that monoglucuronides cannot serve as precursors of sulphoglucuronides.

Animals↗
PubMed1982

[Results of quality control surveys for urinary calculus analyses].

In 1980 and 1981, four quality control surveys for urinary calculus analyses were carried out, within the framework of external quality controls of the Deutsche Gesellschaft für Klinische Chemie. During these quality control surveys the participating laboratories received a total of 16 samples (eight pure substances and eight mixtures of two components), to be analyzed qualitatively and quantitatively. For the qualitative analyses, a laboratory could provide simplified descriptions of the analytes - for example, without stating the number of molecules of the water of crystallization; or, to the extent permitted by the mode of analysis, the exact chemical composition could be presented. Of 1283 analyses, 818 (64%) attained the goals of the simplified analysis. The most frequent errors in chemical analyses were false negative and false positive results for calcium oxalate, and false negative results for calcium phosphate. Laboratories using analysis by infrared spectroscopy also submitted the biggest proportion of incorrect analyses for these components. The most reliable results were produced by X-ray-diffraction: 86% of the results in this category represented correct differentiated analyses. The generally accurate results achieved by some participants using chemical analysis suggest, however, that - in addition to the principle of analysis used - the qualification of the operator is an important determinant in the reliability of the results.

Calcium Oxalate↗
PubMed1981

Immunohistochemical localisation of alpha-fetoprotein (AFP) in germ cell tumours: evidence for AFP production by tissues different from endodermal sinus tumour.

20 germ cell tumours have been studied with respect to the presence of alpha-fetoprotein (AFP), using the peroxidase-antiperoxidase (PAP) technique. 6 out of 20 tumours contained elements of endodermal sinus tumour (EST) and were AFP positive. 16 tumours were diagnosed either as pure embryonal carcinomas (6) or as mixed germ cell tumours, containing elements of embryonal carcinoma (10). In 3 of these 16 tumours AFP was localised definitely in the embryonal carcinoma cells; in an additional 6, AFP was also detected but it could not be decided whether AFP was present in embryonal carcinoma cells or in EST cells during early differentiation. In 2 of 7 immature teratomas, AFP was shown to be present in cylindric epithelia. All seminomas (4) studied were AFP-negative. These results show that AFP, which occurs regularly in EST, may also be present in embryonal carcinomas as well as in immature teratomas. Thus, it seems that the immunohistochemical demonstration of AFP by the PAP technique is a suitable method of identifying late stages of embryonal carcinoma or early stages of endodermal sinus tumour during the process of differentiation.

Dysgerminoma↗
PubMed1981

Effect of rifampicin on the biosynthesis of testosterone in rat testis.

Male Wistar rats were treated with rifampicin (10 mg/kg) daily for 5 days. After 6 days, the rats were killed and the testes homogenised in tris buffer. The microsomal fractions were incubated with [4-14C]4-progesterone, [4-14C]17-hydroxyprogesterone or [4-14C]-androstene-3, 17-dione, respectively, and a NADPH generating system. In rifampicin-treated animals, less [4-14C]progesterone was recovered after incubation with testicular microsomes than in controls. There was no significant difference in the formation of 17-hydroxyprogesterone between rifampicin-treated animals and the controls; however, a significant increase was found in the androstenedione fraction (+83%) and the testosterone fraction (+48%) under the influence of rifampicin. When [4-14C]17-hydroxyprogesterone or [4-14C]4-androstene-3, 17-dione were incubated, no differences in the metabolic pattern were observed between treated and untreated rats. These findings suggest that rifampicin stimulates the activity of 17 alpha-hydroxylase in the microsomal fraction of rat testes, thus leading to an increased formation of testosterone and androstenedione; in contrast, the 17, 20-lyase and 17 beta-hydroxysteroid-dehydrogenase remain unaffected by rifampicin.

Androstenedione↗
PubMed1981

Effect of oestradiol-17 beta on the metabolism of noradrenaline in brain slices of ovariectomized rats.

Ovariectomized rats received a single injection of 10 microgram oestradiol-17 beta 3-benzoate; 90 min or 19 h after injection, slices of various brain areas were prepared and incubated with tritiated noradrenaline for 30 min. Methylated and non-methylated metabolites of tritiated noradrenaline were determined after chromatographic separation. Nineteen h after administration of oestradiol-17 beta 3-benzoate, the formation of normetanephrine, 3-methoxy 4-hydroxy phenylglycol and 3-methoxy 4-hydroxy mandelic acid was decreased (P less than 0.05) in hypothalamic tissue, whereas that of 3,4-dihydroxy mandelic acid was increased (P less than 0.001). In thalamus tissue a decrease or normetanephrine (P less than 0.005) and an increase of 3,4-dihydroxy mandelic acid (P less than 0.001) were also observed. No conclusive results were obtained with hypophyseal tissue. The present findings suggest that oestrogens reduce the methylation of noradrenaline, probably through a competitive inhibition of the catechol-O-methyl-transferase by 2-hydroxylated oestrogens.

Animals↗
PubMed1981

Localization and concentration of carcinoembryonic antigen (CEA) in gastrointestinal tumors: correlation with CEA levels in plasma.

In 50 patients with gastrointestinal carcinomas, the following tumor parameters were studied: the concentration and localization of carcinoembryonic antigen (CEA) in tissue, extension, invasion, infiltration, differentiation, and necrosis. CEA concentrations were measured in plasma samples of all patients. In 7 patients with gastric carcinomas, CEA concentrations in tissue were low. Generally, only single cells or cell groups were CEA-positive. Elevated CEA levels in plasma resulted mainly from distant metastases and not from the primary tumor. In 43 colorectal carcinomas, CEA concentrations in tissue varied between 1.5 and 472 microgram/g tissue. They were closely related to the degree of accumulation of CEA-positive necrotic material in the degree of accumulation of CEA-positive necrotic material in the neoplastic glands. In 35 patients with colorectal carcinomas without CEA producing distant metastases, preoperative CEA levels in plasma were normal when tumor necrosis and perineural invasion were absent and CEA concentrations in tissue were low. CEA levels in plasma were regularly elevated when the tumor showed considerable necrosis in the presence of high CEA concentrations in tissue.

Carcinoembryonic Antigen↗
PubMed1981

Circadian changes of clinical chemical and endocrinological parameters.

It is known that all forms of life possess biological rhythms. The structure of this biological daily periodicity is caused by endogenous and exogenous factors. The reasons of circadian periodicity are endogenous processes, which can be modified by exogenous factors. This review describes the daily fluctuations of concentrations or excretions of haematologic, clinical chemical and endocrinological parameters. In blood and serum the largest daily variations are found for the concentrations of haemoglobin, potassium, iron, cortisol, testosterone, somatotropin, prolactin, adrenaline and noradrenaline. In contrast to the serum concentrations of the electrolytes sodium, potassium, calcium and phosphate, their urinary excretions demonstrate pronounced daily rhythms with amplitudes being twice as high as the daily means. There is a remarkable phase shift of 180 degrees between phosphate and the cations both in the serum concentrations and urinary excretions. A daily rhythm comparable to the urinary excretion of electrolytes, has been measured for the urinary excretion of adrenaline, noradrenaline and cortisol. A constant, well defined timing of the sampling is important for those constituents with a marked daily variation. For numerous parameters very contradictory results have been reported in the literature concerning their daily variations, especially in cases of less pronounced rhythms. For some parameters the reasons for the differences in the observed daily variations are discussed.

Animals↗