[Implants in middle ear surgery].
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Biocompatible Materials↗
Biomedical subjects
G Geyer
Publications and source records attributed to G Geyer.
[Treatment of prolactinoma with a new dopamine agonist].
Eleven patients (6 men, 5 women, mean age 42 [25-65] years) with prolactinomas were treated for 4-16 months with a new dopamine agonist (CV 205-502), at a daily dose of between 0.075 and 0.45 mg. All patients had previously undergone surgery and/or been treated with bromocriptine or lisuride, but had not tolerated this therapy well, and/or had not shown sufficient suppression of serum prolactin levels. Baseline prolactin levels were between 149 and 4120 ng/ml. During treatment, levels fell significantly in all patients, to between 2.0 and 683 ng/ml, and to within the reference range in five patients. In seven patients, the adenoma size decreased by 10 to greater than 50%. Adverse reactions were less frequent and less marked than with the prior therapy. The new dopamine agonist is an alternative treatment for prolactinomas where other therapies have been unsuccessful.
Adult↗
Tetracosactrin vs. methylprednisolone in the prevention of emesis in patients receiving FEC regimen for breast cancer.
0.5 mg tetracosactrin is considered to be equivalent to 40 mg methylprednisolone with regard to the induced cortisol secretion. 97 female breast cancer patients who received their first two FEC courses (epirubicin 50-75 mg/m2, 5-fluorouracil 500 mg/m2, cyclophosphamide 500 mg/m2) entered this randomised crossover study (76 had previously received an adjuvant treatment); tetracosactrin was administered intramuscularly and methylprednisolone intravenously immediately before chemotherapy administration. The tolerability was evaluated using a diary card during 5 days and patients were asked for their preference at the end of the two cycles. There was no difference either for vomiting (dry heaves were included) or nausea between the two treatments (the analysis was performed on day 1, the worse day of days 2 and 3 and the worse day of days 4 and 5). At day 1, 49% of the patients experienced no or mild nausea after tetracosactrin and 62% after methylprednisolone (not significant) (first period analysis); a complete control of vomiting (including dry heaves) was observed in 49% of the patients after tetracosactrin and 53% after methylprednisolone (not significant). No difference was observed between patients with or without previous chemotherapy. However, slightly more patients preferred tetracosactrin (P = 0.048).
Antineoplastic Combined Chemotherapy Protocols↗
Medroxyprogesterone acetate lowers plasma corticotropin and cortisol but does not suppress anterior pituitary responsiveness to human corticotropin releasing factor.
The endocrine action of medroxyprogesterone acetate (MPA) has been claimed to be of a glucocorticoid-like nature. Upon clinical observation, MPA has been shown to improve life quality and overall well-being in patients with advanced breast cancer, renal carcinoma, prostatic carcinoma, and uterine adenocarcinoma. The authors have evaluated MPA endocrine action by the administration of human corticotropin releasing factor (hCRF) in a 90-minute assay in 15 patients with advanced breast cancer or renal cell carcinoma both, before the initiation of oral high-dose MPA treatment (1000 mg MPA) as well as after at least 10 days of therapy. The curves for corticotropin, beta-endorphin, and cortisol responses to hCRF of tumor patients who were tested before the initiation of MPA treatment were parallel to the curves of a healthy control group of probands tested under equal conditions, although at significantly higher respective hormone levels. In patients with malignant disorders assayed after MPA administration, both basal and peak hormone levels were found to be comparable with values obtained in healthy controls. In conclusion, MPA appeared to act at a suprapituitary level since pituitary responsiveness to hCRF was preserved under MPA treatment. Moreover, it appeared that MPA brought the hormonal stress state found in patients with malignant tumors back to normal.
Administration, Oral↗
Horseradish peroxidase as a label of injured cells.
The present study is concerned with artifacts likely to occur in a horseradish peroxidase exclusion test. Incubation of murine peritoneal macrophages and lymphocytes with the peroxidase showed a close relationship between the number of living cells and the percentage of cells excluding the tracer. The penetration of the cytoplasm by horseradish peroxidase is attributed to an increase in the permeability of the cell membrane during the incubation (ranging from 10 to 120 min). It was not increased by the presence of tracer throughout the incubation period. However, concomitant fixation of the cell in the presence of horseradish peroxidase caused an increase in the influx of the tracer. The horseradish peroxidase exclusing test applied to the guinea-pig organ of Corti has proved to be valid provided that: (a) mechanical lesions prior to the tracer incubation are avoided; (b) incubation is terminated by removal of the extracellular tracer; (c) fixation is carried out as soon as possible; (d) a low concentration of horseradish peroxidase is used; and (e) specimens are incubated in diaminobenzidine-H2O2 medium for the shortest possible period. Although fixation-induced cytoplasmic infiltration by horseradish peroxidase was not detected in cochlear specimens, the findings call attention to possible sources of error and define the level of significance of the test. Horseradish peroxidase does not appear to be a cytotoxic agent under the conditions used.
Animals↗
Rat endo- and mesothelium lack Fc receptors.
The present study is concerned with the interaction of rat endo- and mesothelium with homologous erythrocytes under various conditions of pretreatment and incubation. Its findings show rat endo- and mesothelial cells a) nonadhesive to native or pretreated erythrocytes irrespective of the presence of gamma-globulin in the medium, b) devoid of primary or cryptic receptors sensitive to the Fc segment of the IgG molecule, and c) provided with binding sites at the oxidized glycocalyx which together with receptor groups of modified erythrocytes share the same class of IgG.
Agglutination↗
Hypotonic unmasking of erythrocyte receptor sites.
The study reports on plasmalemmal perturbation of erythrocytes under osmotic stress. In comparison with isotonic human erythrocytes a 10 minutes incubation in 150 mosm sodium cacodylate pH 7.4 at 20 degrees C results in an increase of the anti AH P binding rate by a factor of two. 0.1 M N-acetyl galactosamine inhibits the binding of anti-AH P of both isotonic and hypotonic red cells. Contrary to isotonic mouse erythrocytes the agglutination with peritoneal murine leukocytes of hypotonic red cells is greatly enhanced provided the erythrocytes have been incubated in autologous serum. The findings are considered evidence of the unmasking of binding sites due to nonspecific rearrangement of membrane constituents.
Acetylgalactosamine↗
Alteration of the enucleating erythroblast glycocalyx.
Plasmalemmal differentiation of the enucleating normoblast of rabbit and rat was studied by means of cytochemical methods and freeze-etching. Staining with colloidal iron revealed about identical amounts of iron particles bound to various areas of the normoblast membrane. Cationized ferritin and ruthenium red, likewise, failed in the demonstration of significant changes of the enucleating normoblast glycocalyx. Despite these findings the topo-optical staining with toluidine blue showed the plasmalemmal envelope of the protruding normoblast nucleus moderately birefringent, clearly discriminated from the intense anisotropic staining of the future reticulocyte membrane. The ferritin-labeled snail lectin anti AHP localized a great number of binding sites at the plasmalemmal envelope of the nucleus under extrusion. That is in sharp contrast with rather low lectin binding to the future reticulocyte membrane which amounts to about 30 to 50% of the nuclear envelope label. The findings provide evidence of unmasking of bindings sites of the normoblast membrane. Apparently, the effect is due to conformational changes of the cell membrane, rather than it could be attributed to degradation of glycoproteins. Moreover, enucleation kinetics may also be related to supramolecular changes of membrane structure albeit missing evidence for the rearrangement of membrane particles.
Animals↗
CPC-PTA section staining of acid glycans.
A cetylpyridinium chloride-phosphotungstic acid procedure suggested by Kelényi and Kiss (1976) for the staining of mast cell granules in ultrathin sections was slightly modified with regard to pretreatment, pH of incubation, and rinsing of sections. The method also proved suitable for the demonstration of various mucosubstances and of cartilage proteoglycan aggrebates.
Animals↗
Decay of murine intestinal epithelial cells under extrusion.
Electron microscopic findings of this study revealed 2 types of extrusion of brush border cells from the summits of intestinal villi: a) By expansion of initial vacuolation the degenerating cell enlarges and elevates itself above the level of the extrusion zone. Cells about to lift become sphered and are shed into the lumen for degradation to continue. b) Another group of cells vacuolating to a similar extend already may start apical decay in situ. In this case mechanical elevation, apparently, is inefficient or retarded such as to offer a cell the opportunity to decompose at its proper place in the mucosal lining. Contrary to type A extrusion, i.e. the desquamation of the entire degenerating cell, type B produces cellular debris to be shed into the lumen. Either type of exfoliation may be associated with the formation of gaps the closure of which proceeds slowly. The light microscopic test of cell viability by means of horseradish peroxidase demonstrated many brush border cells leaky such as to become loaded with the tracer irrespective of its vascular or enteric approach to the extrusion zone. Damage of the cell membrane due to a brief pretreatment with digitonin resulted in a dramatic rise of horseradish peroxidase positive cells. With respect to these findings, one cannot escape the conclusion that both types of extrusion confer intermittent leakage on the summits of intestinal villi which at least could account for part of the diffusion of macromolecules in either direction.
Animals↗
[Electron microscopic autoradiography on semithin sections (author's transl)].
The present study applies semithin sections for electron microscopic autoradiography. Due to (a) the decrease of exposition time, and (b) lower intensity of isotope labelling, low power electron microscopic autoradiography on semithin sections is favoured in comparison with conventional (ultrathin section high power) electron microscopic autoradiography, and due to (c) more precise localization of silver granules, and (d) ease of quantitative evaluation of autoradiography, it is superior to ordinary (thick section) light microscopic autoradiography.
Animals↗
Negative surplus charge of coated erythrocytes.
The effect on the net negative surface charge of single or multiple coating of erythrocytes was studied on human group A red cells previously washed and fixed. Single coating with either group A antiserum or protectin decreased the electrophoretic mobility of erythrocytes by 16% and 13%, respectively. Following an incubation in group A glycophorin or bovine submaxillary mucin of agglutinin coated cells, the electrophoretic mobility was restored or slightly increased compared with uncoated erythrocytes. Upon repeating this scheme, the second agglutinin binding again reduced these cells' cytophoretic mobility, and they were accelerated once more by a second coating with acid glycoprotein. Intensity and homogeneity of colloidal iron staining of uncoated and variously coated erythrocytes reflected their electrophoretic retardation and acceleration, respectively.
ABO Blood-Group System↗
[Sialic acid content and IgG binding of the glycocalyx of preserved erythrocytes].
Fractions of light and heavy erythrocytes were separated by centrifugation from blood samples banked in ACD-AG medium at 4 degrees C for periods up to 6 weeks. Both light and heavy erythrocytes have lost about 4,9% of their content of sialic acids during banking for 6 weeks. This reduction is in accord with a 6%-decrease of their agglutination by means of alcian blue. It is, however, a variance with the inhibition of agglutination by anti-IgG sera. The present findings provide evidence for the role alterations of the red cell membrane may play in the process of recognition and phagocytosis of banked erythrocytes. With regard to these alterations we suggest two types of rapid elimination of transfused banked erythrocytes: a) Primary elimination refers to cells primarily loaded with immunoglobulins such as to get recognized and phagocytized by macrophages. b) Secondary elimination accounts for rigid erythrocytes suffering from additional degradation while retained in the spleen prior to their loading with immunoglobulins and ensuing phagocytosis. Secondary elimination is considered a process more relevant to reutilisation of banked blood.
Binding Sites, Antibody↗
[A ruthenium red-osmium tetroxide section staining method (author's transl)].
We suggest a method for the section staining of polyanions by means of ruthenium red and osmium tetroxide. A 5 min incubation in diluted ruthenium red-OsO4 solution pH = 7.4 of ultrathin Durcupan-sections previously treated with sodium methoxide results in the opaque stining of mast cell granules, cartilage proteoglycans, and various epithelial mucosubstances.
Animals↗
Endolymphatic leakage in case of acute loss of cochlear microphonics.
Rapid loss of cochlear microphonics in guinea-pigs previously exposed to high-energy impulse noise was shown to be related to the breakdown of the endolymphatic boundary. The cochlear duct was rendered leaky by deterioration of the reticular membrane, and damage of sensory and supporting cells.
Animals↗
Effect of in vivo administration of somatostatin on cell-free protein synthesis of pituitary and of adrenal ribosomes.
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Adrenal Glands↗
A peroxidase exclusion test for cell viability.
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Animals↗
Toluidine blue staining of cartilage proteoglycan subunits.
Selective binding of toluidine blue to basophilic proteoglycans is the first stage of a staining method which proceeds to the formation of a heavy metal salt of the dyestuff. By means of this procedure matrix complexes of hyalin cartilage were stained such as to display granular subunits about 25 to 35 A in diameter. The findings are interpreted as the demonstration of proteoglycan constituents of chondromucin aggregates.
Animals↗