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Biomedical subjects

A Müller

Publications and source records attributed to A Müller.

At least 595 records · Page 33Linked to original sources
PubMed1983

Sonographic morphology of the breast.

The interpretation of ultrasound mammograms is complicated by the heterogeneous tissue structure of the breast. To improve the diagnostic analysis, a method has been developed which enables us to correlate ultrasound images of mastectomized specimen with the cross-sectional anatomy, the computerized tomography, the X-ray photographs of the specimen and the histopathologic study of the corresponding gross serial sections. Some echophenomena considering the propagation properties of ultrasound are discussed.

Breast↗
PubMed1983

Ultrasonic diagnosis of malignant and benign human breast lesions.

Since 1979 445 ultrasound examinations of the breast have been performed. Histological examinations took place in 268 cases. There were 91 patients with 97 carcinomas (5 patients had multicentric carcinomas). In every case x-ray mammography preceded ultrasound examination. The over-all detection rate of malignant breast lesions was 90% by ultrasound examination and corresponded well to the x-ray mammographic findings with 93%. However, false positive results were obtained in 28% of the patients on the basis of sonographic examination. Cysts--with an incidence of 12% in all benign changes in this study--were always correctly diagnosed by ultrasonography. According to these results ultrasonography of the breast may be considered a meaningful additional method to preoperative examination.

Breast Diseases↗
PubMed1983

Quantitative angiographic assessment of coronary stenoses: problems and pitfalls.

A precondition for quantitative angiography is strict standardization of all geometric parameters, i.e., position of the patient and radiation-source-object-image geometry. Correction for respiratory and cardiac cycles is equally important. When all these variables are controlled, the absolute size of a vessel can be a major source of error, since border recognition becomes progressively difficult with decreasing vascular diameter. Finally, contrast density, independent of vascular geometry, will induce errors by virtual magnification of minimal diameters. The results in this paper show the influences of image intensifier position, angulation of the imaging device, and contrast concentration on the geometry of model coronary stenoses when evaluated with computer-assisted quantitative methods. Increase of object-image intensifier distance led to an underestimation of size which increased with decreasing vascular diameter. Decrease in contrast concentration led to a significant overestimation of actual size, up to 20% (p less than 0.05). This effect could be confirmed in human coronary arteriograms (n = 11, p less than 0.05). In conclusion, realistic contrast-perfused calibration devices will have to be developed to replace wire or plaster models in order to control systemic errors that may impede the measurement of absolute vascular size.

Contrast Media↗
PubMed1983

[Echomorphology of the breast. Comparative sonographic, radiologic, anatomic and histologic studies of breast specimens].

The interpretation of ultrasound mammograms is complicated by the heterogeneous structure of breast tissue. To improve the diagnostic analysis, a method has been developed which enables us to correlate ultrasound images of mastectomized specimens with the cross-sectional anatomy, the computed tomography, the x-ray photographs of the specimen and the histopathologic study of the corresponding gross serial sections. Some echophenomena considering the propagation properties of ultrasound are discussed. Echodense areas correlate well with inhomogeneous structures of the glandular tissue, i.e. the continuous change of microcystically alterated alveoli, dense and looser connective tissue, dilated ducts and small fat lobules. The histomorphologic equivalent to less echogenic lesions is represented by a homogeneous tissue structure, for example the homogeneous fibrosis of glandular tissue or tumourous tissue. Even fatty tissue appears echopoor. Shadowing phenomena are explained by refraction and absorption effects. The topographic comparison of echograms with identical x-ray photographs of specimen slices emphasizes that the sonographic examination of the breast can enhance the radiographic findings and therefore improve the diagnostic accuracy.

Breast↗
PubMed1982

Nuclear oestrogen receptors in rat liver. Development of assay conditions, characterization and the translocation of oestrogens in vivo.

A method for the determination of specific oestrogen-receptor binding sites in rat liver nuclei is described. Nuclear receptors showed a high affinity for oestradiol (Kd approximately 3 x 10(-9)M), a low capacity, and a distinct specificity for substances with known oestrogenic and anti-oestrogenic activity. No sex differences were seen in the concentrations of nuclear receptors from either vehicle- or ethynyloestradiol-pretreated rats. Only a limited number of binding sites could be extracted with 0.4 M-KCl. The remaining sites, which were solubilized by sonication and treatment with deoxyribonuclease I, sedimented at 3-4 S. Of four oestrogens tested (oestradiol, ethynyloestradiol, diethylstilboestrol, tri-p-anisylchloroethylene), ethynyloestradiol was the most effective translocation agent in vivo, nuclear uptake occurring at doses below 1 microgram/rat; changes in salt extractability of nuclear receptors occurred at doses lower than those required to achieve absolute increases in nuclear receptor concentrations.

Animals↗
PubMed1982

Role of alcohol dehydrogenase activity and the acetaldehyde in ethanol- induced ethane and pentane production by isolated perfused rat liver.

The volatile hydrocarbons ethane and n-pentane are produced at increased rates by isolated perfused rat liver during the metabolism of acutely ethanol. The effect is half-maximal at 0.5 mM-ethanol, and its is not observed when inhibitors of alcohol dehydrogenase such as 4-methyl- or 4-propyl-pyrazole are also present. Propanol, another substrate for the dehydrogenase, is also active. Increased alkane production can be initiated by adding acetaldehyde in the presence of 4-methyl- or 4-propyl-pyrazole. An antioxidant, cyanidanol, suppresses the ethanol-induced alkane production. The data obtained with the isolated organ demonstrate that products known to arise from the peroxidation of polyunsaturated fatty acids are formed in the presence of ethanol and that the activity of alcohol dehydrogenase is required for the generation of the active radical species. The mere presence of ethanol, e.g. at binding sites of special form(s) of cytochrome P-450, it not sufficient to elicit an increased production of volatile hydrocarbons by rat liver.

Acetaldehyde↗
PubMed1982

Digoxin does not alter plasma steroid levels in health men.

Digoxin has been reported to induce feminizing effects in man. It does not compete for estradiol cytosol receptors in human breast carcinoma cells, however, and has no uterotrophic effect. We therefore investigated whether feminization might be due to digoxin action on plasma concentrations of sex steroids. Six healthy men (31.5 +/- 4 yr old) received therapeutic doses of digoxin for 43 days. We measured plasma concentrations of testosterone, androstenedione, dehydroepiandrosterone, estrone, estradiol, progesterone, 17-hydroxyprogesterone, cortisol, and aldosterone. During 35 days on digoxin levels of these steroids remained in the normal range and there was no change from before-drug values. Digoxin was in the therapeutic range of 1.9 +/- 3 nmol/l throughout. After stimulation by adrenocorticotropic hormone or human choriongonadotropin, the rise in plasma steroids was in the same range as when digoxin was given, as well as 16 wk after it had been discontinued. A normal rise in luteinizing hormone after luteinizing hormone-releasing hormone showed that the hypothalamogonadal feedback was not altered by digoxin. Free testosterone, estradiol, and cortisol concentrations under basal conditions and after stimulation were also the same before and after drug. It is concluded that the estrogen-like activity of digoxin cannot be explained by altered steroid availability from plasma. Feminizing effects attributed to digoxin may be caused by other conditions known to influence sex steroid hormones that are common in patients with heart disease. Our data suggest that digoxin may be the preferred digitalis therapy to avoid feminizing effects.

Adrenal Cortex Hormones↗
PubMed1982

Pharmacologically induced changes in human beta-chorionic gonadotropin (beta-hCG) synthesis by human placenta in organ culture.

In organ cultures the regulation of beta-hCG formation in human placentas of early gestation (EG) and at term (T) was analyzed using the following test substances: dibutyryl cAMP (dbcAMP), theophylline, and by two drugs used to treat patients with premature labor, fenoterol hydrobromide and verapamil hydrochloride. The rapid increase in beta-hCG in culture medium beginning at 24-48 h corresponds to morphologic changes (proliferation of the cytotrophoblast). Beta-hCG synthesis of human placenta is related to an adenylate cyclase as could be shown by dose-dependent stimulation by dbcAMP (T) (after 72 h) (controls = 100%): 2 nM = 125%; 70 nM = 200%; 2 microM = 300%. Similar results were obtained using EG. First stimulation by dbcAMP was found after 2 h and may be caused by a release of intracellular beta-CG or by a direct stimulation of beta-hCG synthesis; late effects (after 48-72 h) are suspected to be due to changes in morphologic differentiation of the placenta in organ culture. Theophylline (0.1 and 1 mM) did not influence beta-hCG formation in EG, whereas in T a dose-dependent stimulation could be achieved (controls = 100%): 0.1 mM = 110%; 1 mM = 300%; and 10 mM = 160%. Fenoterol hydrobromide, a tocolytic beta 2-receptor stimulating agent showed a slight (130-160%) beta-hCG stimulation (after 72 h) (EG and T). The stimulatory effect of a high dose (1 microgram/ml) of fenoterol hydrobromide could be due to a stimulation of beta 2 receptors related to an adenylate cyclase. Dose-related changes in beta-hCG in T were found for the calcium antagonist verapamil hydrochloride (controls = 100%): 0.01 microgram/ml = 125% stimulation; 0.33 microgram/ml = 200% stimulation; 10 micrograms/ml = 100%. As indicated by verapamil tests, calcium ions may play a role in the regulation of beta-hCG production.

Bucladesine↗
PubMed1982

Active oxygen metabolites and their action in the hepatocyte. Studies on chemiluminescence responses and alkane production.

"Oxidative stress" takes place in animal tissues when the balance between the cellular defense mechanisms (glutathione cycle, superoxide dismutase, catalase, vitamin E, etc.) and conditions capable of triggering oxidative reactions is altered. The oxidative reactions which occur under a variety of conditions were assessed by two non-invasive methods, low-level chemiluminescence and volatile hydrocarbon production. Oxidative stress induced by hyperoxia or organic hydroperoxides in isolated hepatocytes or the perfused liver, respectively, is accompanied by low-level chemiluminescence, the intensity of which is enhanced upon perturbation of the glutathione cycle system, i.e., glutathione depletion and/or selenium deficiency. Oxidative stress during redox cycling of paraquat, when infused into the perfused liver, is not accompanied by light emission, whereas menadione, a substance also capable of redox cycling, was found to elicit photoemission under similar conditions. The basal rates of ethane release by the perfused liver are enhanced during oxidative conditions such as metabolism of hydroperoxides, paraquat redox cycling, and ethanol oxidation. Alkane release during the latter involves the participation of alcohol dehydrogenase and further products of ethanol oxidation, i.e., acetaldehyde, as well as free radicals in some stage of the process. In vivo ethane release by animals with adjuvant arthritis was found higher than in controls, presumably due to a systemic response of liver to inflammation.

Alkanes↗
PubMed1981

Acute saline expansion lowers blood pressure of early DOCA salt hypertensive rats.

Changes in blood pressure and body fluids volume caused by an acute saline load were studied in 6 normal and 7 DOCA-salt early hypertensive rats having normal inulin space and plasma volume. After loading, blood pressure increased in the normal group (+23 mm Hg) and fell (-17 mm Hg) in the DOCA-salt group. Expansion of extracellular fluid volume was similar in both groups but expansion of plasma volume was twice as high in the DOCA-salt than in the normal group. The results are compatible with an inhibition of a volume-sensitive vasopressor mechanism possibly involving vasopressin.

Animals↗