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Biomedical subjects

A Dorn

Publications and source records attributed to A Dorn.

At least 91 records · Page 5Linked to original sources
PubMed1986

The extracellular electrical current pattern and its variability in vitellogenic Drosophila follicles.

We determined the extracellular electrical current pattern around Drosophila follicles at different developmental stages (7-14) with a vibrating probe. At most stages a characteristic pattern can be recognized: current leaves near the oocyte end of the follicle and enters at the nurse cells. Only at late vitellogenic stages was an inward-directed current located at the posterior pole of many follicles. Most striking was the observed heterogeneity both in current pattern and in current density between follicles of the same stage. Different media (changed osmolarity or pH, addition of cytoskeletal inhibitors or juvenile hormone) were tested for their effects on extrafollicular currents. The current density was consistently influenced by the osmolarity of the medium but not by the other parameters tested. Denuded nurse cells (follicular epithelium locally stripped off) show current influx, while an accidentally denuded oocyte produced no current. Our results show that individual follicles may be electrophysiologically different, though their uniform differentiation during vitellogenesis does not reflect such heterogeneity.

Animals↗
PubMed1986

[Low-molecular cysteine protease inhibitors in the human palatal tonsil].

2 low-molecular cysteine-proteinase inhibitors were purified from human tonsillar tissues: an acid cysteine proteinase inhibitor (ACPI), and a neutral cysteine proteinase inhibitor (NCPI). Their biochemical and immunological characteristics appeared to be identical to those inhibitors which we have identified in other human tissues in previous studies (epidermis and spleen). An immunohistological analysis revealed in tonsillar squamous epithelium a strong and consistent immunoreactivity for both inhibitors. In the tonsillar lymphatic tissue, ACPI-immunoreactivity appeared to be a characteristic mainly of dendritic reticulum cells whereas a prominent NCPI-immunoreactivity was confined mostly for the histiocytic reticulum cells in lymphoid secondary follicles. We also compared the distribution of the 2 immunoreactive inhibitors with the immunohistology as revealed by antisera raised against keratin and muramidase. Limitations of the immunohistochemistry of cysteine proteinase inhibitors are discussed in the light of an extensive trial of various fixation procedures. We deem that proposal of Barrett (1984) for the nomenclature of cysteine proteinase inhibitors is appropriate. According to it the ACPI is the cystatin A, and the NCPI is the cystatin B.

Child↗
PubMed1986

Immunohistochemical demonstration of ornithine decarboxylase in tissues. A preliminary study.

Using the unlabeled immunoenzyme technique, ornithine decarboxylase immunoreactivity was demonstrated in rat prostate gland and kidney. Three types of prostate epithelial cells could be revealed, displaying different strength of ODC immunoreactivity. In rat kidneys, ODC was found in proximal and distal tubules of immature tissue. Both tissues served as paradigms to optimize the immunohistochemical approach for ODC localization.

Animals↗
PubMed1986

Postnatal changes in thiol: protein-disulfide oxidoreductase immunoreactivity of rat brain.

Thiol: Protein-disulfide oxidoreductase (TPO) was localized in the brain of juvenile and adult rats by use of the unlabeled immunoperoxidase technique. In the brain of adult animals, TPO protein was revealed in neurons of Nucc. supraopticus and paraventricularis as well as in the subcommissural organ. In the developing rat, TPO seems to be a constituent of almost all neurons. The roles played by the enzyme remain to be elucidated, however.

Aging↗
PubMed1986

Cathepsins B and D in rat brain glia during experimentally induced neuropathological defects. An immunocytochemical approach.

The lysosome-associated cathepsins B and D were localized by means of immunocytochemistry (peroxidase-antiperoxidase technique) in glial cells of rat brain. A specific reaction pattern of hippocampal neuroglia could be observed after intracerebroventricular application of the neurotoxin kainic acid. After the induction of a focal epilepsy in rats by the implantation of cobalt pellets there was a pronounced immunoreaction of glia near the primary focus as well as the mirror focus. It is concluded that both cathepsins are useful immunocytochemical markers to trace functionally activated glia.

Animals↗
PubMed1986

Immunohistochemical analysis of the distribution of cathepsin D throughout human nervous system with reference to developmental aspects.

The aspartic endopeptidase cathepsin D was demonstrated in post mortem human brain by means of the peroxidase-antiperoxidase technique. The enzyme protein was found to be present in multiple neurons as well as in some glial cells. In embryonic nervous tissue cathepsin D was detected as early as at the 12th gestational week. During neuroontogenesis there was a continuous increase in cathepsin D immunoreactivity.

Aged↗
PubMed1985

Rat prostate gland--a good model for demonstration of ornithine decarboxylase by immunohistochemistry.

Ornithine decarboxylase was localized immunohistochemically in paraffin sections of prostate glands of the rat using Sternberger's PAP technique. Two types of immunoreactive cells were detected in the gland epithelium: strongly positive ones and weakly positive ones. Unreactive cells were also present. The functional role of the enzyme in the secretory process of the glands is discussed in the light of these findings.

Animals↗
PubMed1985

Distribution of cathepsin D immunoreactivity in the central nervous system of rat and selected brain regions of man.

The regional distribution and cellular localization of cathepsin D immunoreactivity was demonstrated at the light microscopic level in the CNS of rat and man by use of unlabelled immunoenzyme technique. A wide but uneven distribution was substantiated for the rat brain. Furthermore, we present evidence that antiserum produced against rat liver enzyme is capable of recognizing cathepsin D in human brain.

Animals↗
PubMed1985

A polypeptide immunoreactive nonchromaffin paraganglioma in the periglandular connective tissue of glandula suprarenalis of a dog. A case report.

A nonchromaffin paraganglioma was found in the periglandular connective tissue of the glandula suprarenalis of a sheep-dog bastard and characterized by histological and immunohistochemical techniques. Insulin-, glucagon- and gastrin/cholecystokinin-like material was revealed within the cells of the tumour. Possible functional consequences of these findings are discussed.

Adrenal Gland Neoplasms↗
PubMed1985

Attachment of sponge cells to collagen substrata: effect of a collagen assembly factor.

Collagen, isolated from the sponge Geodia cydonium in the absence of denaturing agents, had the typical amino acid composition and was associated with the carbohydrates galactose and glucose. The resulting individual fibrils with a diameter of 23 nm, displayed a 19.5 nm periodicity with one intraperiod band. A collagen assembly factor (CAF) was identified in and partially purified from the extracellular space. The CAF reacted with antibodies against intact Geodia cells but not with antibodies against Geodia lectin and Geodia aggregation factor. In the presence of the CAF, the collagen fibrils reconstituted collagen bundles in an ordered sequence of events, which were followed by electron-microscopical and biochemical methods. Bundle formation was not dependent on the presence of the homologous lectin, glycoconjugates or aggregation factor. Homologous cells (Geodia archaeocytes) were determined to attach only to those Geodia collagen substrates that contained CAF. The attachment of these cells did not require fibronectin or Geodia lectin. Homologous glycoconjugates or NaOH-treated collagen inhibited cell attachment. Collagen from the sponge Chondrosia reniformis, even in the presence of Geodia CAF, was no appropriate substrate for Geodia cell attachment. Whether collagen is a component of cell-matrix interactions in sponge systems also in vivo is discussed.

Animals↗
PubMed1985

The molecular mechanisms of the distinct calcium-dependent aggregation systems in marine sponges and corals.

During the last 15 years we have developed two biological systems, with whom it was possible to study the Ca++-dependent and the Ca++-independent adhesion on cellular level. In contrast to cells from other multicellular organisms, cells from the marine sponge Geodia cydonium are provided with Ca++-dependent adhesion mechanisms only. Two different mechanisms have been discovered by us, which were termed primary aggregation and secondary aggregation. In previous reports, we described that two macromolecules (aggregation factor [sAF] and aggregation receptor [AR] are involved in the secondary aggregation of sponge cells. The sAF was bound to a high-molecular-weight particle and was termed aggregation complex. The aggregation complex was shown to consist of two further functional subunits: UDP-glucuronosyltransferase and UDP-beta-D-galactosyltransferase. The AR with a molecular weight of approximately 17,000 was found to be a glycoprotein with D-glucuronic acid as the terminal sugar moiety. Data are presented from in vitro and in vivo experiments with the Geodia system, indicating that cell aggregation and cell separation are controlled first by alteration of the binding capacity of the aggregation receptor and second by an additional molecule (anti-aggregation receptor), which can decrease the interaction between the aggregation factor and the aggregation receptor. Recently we succeeded in the identification and isolation of the primary aggregation factor (pAF) from the same sponge species. This pAF is a glycoprotein that is firmly associated with the cell membrane. The Mr of the native pAF was 36,000; under denatured conditions three protein species were identified in the pAF preparation. We hypothesize that in contrast to the secondary aggregation, the initial aggregation of Geodia cells is mediated by the one-component system, the bivalent and bifunctional pAF. We were also able to dissociate the coral Eunicella cavolinii into single cells. These cells readily formed aggregates of a size of 2,100 micron during incubation in roller tubes: no aggregate formation was observed in non-rotating petri dishes. The formation of aggregates was not influenced by Ca++, urea or trypsin; it was also independent on temperature (4 degrees C to 30 degrees C) and pH (5.5-9.0). The intercellular material of the gorgonian contains a galactose-specific lectin, as determined by double diffusion experiments and haemagglutination inhibition experiments using a series of galacto-glycoconjugates. This lectin converted the aggregation-susceptible cells to aggregation-deficient cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

[Prenatal ontogenesis of human surface cerebral arteries. A mesoscopic, histologic and electron microscopy study].

The prenatal development of the meningeal arteries in human is studied with mesoscopic (stereomicroscopic), histologic and electron microscopic methods. In the ink injected membraneous preparation it can be shown developing and arbituarisation of the arteries, arteriols and venes in the Pia mater as a topographic study. Morphometric investigations should be done. The histologic study (on plastic semithin sections) shows the cellular composition of the vessels and the electron microscopic observations help us to differentiate the cells in the developing vessel's wall.

Capillaries↗