Biomedical subjects

E Buse

Publications and source records attributed to E Buse.

At least 19 recordsLinked to original sources

PubMed2006

Background pathology of the common marmoset (Callithrix jacchus) in toxicological studies.

Two hundred common marmosets (Callithrix jacchus) from control groups (100 males, 100 females) of toxicological studies were examined histopathologically to evaluate the spectrum of spontaneous lesions in this species. Frequent findings were extramedullary hematopoiesis affecting adrenal glands, liver, kidney and spleen, cystic Brunner's glands in the duodenum, acute or subacute inflammation in the large intestine and gall bladder, renal mineralization and pigmentation, hepatic Ito-cell vacuolation, microgranuloma and glycogen storage, pituitary cysts, C-cell hyperplasia and lymphocytic foci of the thyroid gland, luteal hyperplasia of the ovary and inflammatory cell foci in various organs.

Acute Disease↗

PubMed2004

Spontaneous epithelial plaques in the uterus of a non-pregnant cynomolgus monkey (Macaca fascicularis).

Two epithelial plaques were observed in the uterus of a 4 years 8 month old non-pregnant cynomolgus monkey. Normally, epithelial plaques occur near the implantation site of primates during early pregnancy but can also be induced by various procedures. Both plaques consisted of clusters and nest of cells with large nuclei and a faintly basophilic cytoplasm. Marked cellular pleomorphism was seen, including cells with giant nuclei and binucleated cells. Further histological features were vacuolation, mitosis and PAS-positive granules in several cells and polymorphonuclear infiltration in the periphery of the plaque. This is the second description of a spontaneous epithelial plaque in a primate and the first in a cynomolgus monkey.

Animals↗

PubMed2003

Spontaneous squamous cysts and squamous epithelial plaques in the heart of cynomolgus monkeys (Macaca fascicularis).

Squamous cysts and squamous epithelial plaques were observed in a total of seventeen cynomolgus monkeys. Eleven monkeys had squamous cysts, three of them also revealed squamous plaques and six revealed squamous plaques exclusively. At necropsy, cysts were recognized as yellow-white nodules with a smooth surface, that were located superficially along the interventricular septum, on the surface of the left ventricle or the apex of the heart. Microscopically, cysts were lined by a flattened epithelium and filled with keratin. Occasionally the epithelium was multi-layered or replaced by a rim of foreign body-type multinucleated giant cells. All animals with squamous cysts came from Mauritius, while those with squamous plaques came from Mauritius, China and Vietnam. As discussed in man, squamous cysts and plaques in cynomolgus monkeys are considered to represent displaced foregut epithelium, that was sequestered in the dorsal mesocardium prior to closure of the pleuropericardial fold during early embryologic development.

Animals↗

PubMed2001

Spontaneous pulmonary neoplasms in cynomolgus monkeys (Macaca fascicularis)--a report of two cases.

The first lung tumour-bearing animal was a 7 years and 3 months old cynomolgus monkey. Microscopic examination revealed a neoplastic mass under the pleura that consisted of squamous islands with little keratinization, multifocal mineralization of the keratin, inflammatory cell and foreign body-type giant cell infiltration. It was classified as pulmonary squamous cell carcinoma. In a second cynomolgus monkey (2 years and 10 months old) a lung mass was observed at necropsy. Microscopically the tumour consisted of numerous islands of cartilage with glandular structures lined by a cuboidal epithelium between them. The neoplasm was classified as cartilaginous hamartoma.

Animals↗

PubMed2001

The Pars tuberalis of the monkey (Macaca fascicularis) hypophysis: cell types and hormone expression.

The pars tuberalis (Pt) of most mammalian species contains specific cells which are structurally and functionally different from the pars distalis (Pd) cells. Pt-specific cells possess melatonin receptors and reveal morphological changes dependent on the duration of the photoperiod. Furthermore, in hamsters the transmission of photoperiodic stimuli to the endocrine system is influenced by melatonin, an effect which is likely to be mediated by Pt-specific cells. In monkeys, however, only little is known about this cell type. Therefore, we studied the ultrastructural differentiation of Pt-specific cells and describe the expression of different hormones and their mRNA by immunohistochemistry and in situ hybridization. Apparently the Pt consists of (1) cells similar to gonadotropic cells of the Pd, (2) folliculostellate cells and (3) a cell population which is morphologically and functionally clearly distinct from all other cell types found in the Pd. Morphologically they resemble the Pt-specific cells found in other species. Regarding the expression of secretory products there is evidence that they transcribe and translate the beta-TSH subunit. Although there is a strong signal for the mRNA of the common alpha-chain, protein staining is much weaker. POMC mRNA is expressed in the Pt while there is no evidence for PRL mRNA. The present results lead to the conclusion that the Pt of the monkey contains Pt-specific cells which express different hormonal subunits as was already shown for other species. In context with previous findings of melatonin receptors in the monkey Pt further investigations are necessary to establish the possible role of Pt-specific cells in the photoperiod-dependent generation of endocrine rhythms.

Animals↗

PubMed1998

In vitro-model for Toxoplasma gondii invasion into neuroepithelial cells.

In order to study the interactions of Toxoplasma gondii and neuroepithelial cells morphologically and biochemically we established an easy in vitro model, which simulates cellular contacts in congenital toxoplasmosis. Monolayer cultures of neuroepithelial cells from 13-14-day-old mouse embryos were prepared containing the typical ventricular cell types found in an embryonic brain, such as young neurons, macroglial and microglial cells. Ultrastructural investigations on cultures incubated for 1, 5 and 30 min or 1, 6, 12, 24 and 48 h with T. gondii indicated that all three cell types had been invaded by the parasites, multiplying in parasite vacuoles by means of endodyogeny. Microglial cells had already been penetrated by trophozoites within one minute and showed up to 3 or 5 parasite vacuoles per cell. Neurons and glial cells were invaded within 5 min and contained only one vacuole per host cell. All the parasite vacuoles were bounded by a membrane and bordered by the rough endoplasmic reticulum and mitochondria of the host cell after a few minutes. The vacuoles also contained some membranic tubuli. After 30 min some neuronal neurites were destroyed while the perikarya seemed to be unchanged. After 6 h the cytoplasm of the microglia lost more and more ribosomes and organelles. Neurons and glial cells showed no alterations. After 12h large areas of the vacuole membrane were folded up and lay curled up in the vacuoles. After 24 h incubation T. gondii had destroyed nearly all the microglial cells. The ultrastructure of neurons and glial cells now began to change in the same way as shown for microglial cells. The organelles and cellular membranes disintegrated and after 48 h incubation nearly all the cells in the neuroepithelial cell culture had fallen to pieces. For an identification of T. gondii in vitro by light microscopy or for the characterization of the cell surface we tried to label the parasites with 11 different FITC-stained lectins. None of the tested lectins bound to the parasites. We conclude that our in vitro-model for invasion of T. gondii in neuroepithelial cells opens an opportunity for studying the interaction of these cells or the pharmacological effects on this interaction under defined conditions.

Animals↗

PubMed1998

Glycoconjugate expression during early mouse oculogenesis.

The carbohydrate side-chain of glycoconjugates can show a developmentally regulated expression pattern. In order to analyse these changes during the development of the eye, 13 lectins were used to reveal glycoconjugates histochemically in 8.5- to 14-day-old mouse embryos. During this period, eyes develop from the most immature vesiculation of the neural plate neuroepithelium into a primitive stage with all structures present, such as pigment epithelium, not yet differentiated neuroretina and lens. A striking diversity of carbohydrate side-chain expression was observed in the preocular somatoectoderm and neural plate of 8.5-day-old embryos, as indicated by the binding of nine different lectins. Binding sites at the apical poles of neuroepithelium of five of these lectins (PNA, LCA, SBA, LPA and GSA-II) disappeared completely during further development. The binding sites of four other lectins, WGA, MPA, Con A and BPA, remained expressed during the course of development, being indicative for the carbohydrate side-chains beta-GlcNAc(1-4)Gluc, alpha-Gal(1-3)GalNAc, alpha-D-Man/alpha-D-Gluc and alpha-GalNAc. In contrast, binding sites for GSA-I, RCA-I (alpha-D-Gal), UEA-I (alpha-L-Fuc) and DBA (alpha-GalNAc(1-3)GalNAc) were not present at any developmental stage. The time point of gross changes of lectin binding sites correlates well with the period of neural tube formation. During later development from neuroectoderm to the ocular pigment epithelium, a sharp reduction in all lectin binding sites at the apical cell poles, except for WGA and MPA, was observed. WGA binding sites were present until embryonic day 10, while those for MPA were present until day 9. At the basal cell poles of the pigment epithelium, all lectin binding sites except for WGA were lost after embryonic day 11.5. These results indicate that there are sophisticated kinetics of glycoconjugate expression during the course of early embryonic development of ectoderm into its descendent tissues.

Animals↗

PubMed1998

Development of neuroventricular cells into ocular pigment cells in embryonic chick eyes: morphometrical and electrophysiological observations.

The development of neuro-ventricular cells into pigment cells (outer layer of the optic cup) was studied morphometrically and electrophysiologically in eye primordia of chick embryos. The prospective pigment cells are homogeneous until days 4 to 5 1/2 of embryonic development. During this period, all cells are devoid of pigment and display a basic neuroventricular profile of both inward (probably sodium) and outward (potassium) currents evoked by depolarization. Pigment cell differentiation occurs rapidly between days 5 and 6. On day 6 most cells are pigmented and respond to depolarization with outward currents only. Inward currents were elicted only in a few pigmented cells. By contrast, the minority of unpigmented cells (or cells with faintly dark cytoplasmic inclusions, probably premelanosomes) still present on day six displayed the "immature" pattern of mixed inward and outward currents. We conclude, that the differentiation of neuroepithelial cells into pigment cells involves both the synthesis of pigment granula and the down-regulation of the expression of inward current-mediating ion channels in their membrane.

Animals↗

PubMed1997

Comparative studies on mammalian Müller (retinal glial) cells.

Müller cells from 22 mammalian species were subjected to morphological and electrophysiological studies. In the 'midperiphery' of retinae immunocytochemically labeled for vimentin, estimates of Müller cell densities per unit retinal surface area, and of neuron-to-(Müller) glia indices were performed. Müller cell densities were strikingly similar among the species studied (around 8000-11,000 mm-2) with the extremes of the horse (< or = 5000 mm-2) and the tree shrew (> or = 20,000 mm-2). By contrast, the number of neurons per Müller cell varied widely, being clustered at 6-8 (in retinae with many cones), at about 16, and at up to more than 30 (in strongly rod-dominated retinae). Isolated Müller cell volumes were estimated morphometrically, and cell surface areas were calculated from membrane capacities. Müller cells isolated from thick vascularized retinae (carnivores, rats, mice, ungulates) were longer and thinner, and had smaller volumes but higher surface-to-volume ratios than cells from thin paurangiotic (i.e. with blood vessels only near the optic disc) or avascular retinae (rabbits, guinea pigs, horses, zebras). In whole-cell voltage-clamp studies, Müller cells from all mammals studied displayed two dominant K+ conductances, inwardly rectifying currents and delayed rectifier currents. TTX-sensitive Na+ currents were recorded only in some species. Based on these data, the following hypotheses are presented, (a) neuron-to-(Müller) glia indices are determined by precursor cell proliferation rather than by metabolic demands; (b) Müller cell volumes depend on available space rather than on the number of supported neurons; and (c) it follows that, the specific metabolic activities of Müller cells must differ greatly between species, a difference that may contribute to distinct patterns of retinal vascularization.

Animals↗

PubMed1995

Immunocytochemical localization of glycogen phosphorylase in primary sensory ganglia of the peripheral nervous system of the rat.

Neuronal localization was investigated of glycogen phosphorylase (GP) in ganglia of the peripheral nervous system of the rat. Immunofluorescence and immunoenzymatic procedures were applied with a monoclonal anti-bovine brain GP antibody on paraformaldehyde-fixed, paraffin-embedded tissues. Immunoreactivity was only present in the somatic neurons of the mesencephalic trigeminal nucleus in the brain stem and in dorsal root ganglia (DRG), but not in the autonomic neurons of the superior cervical ganglia or in the sensory nuclei of the spinal cord. GP immunoreactivity was present as early as day 1 after birth. In the adult rat, staining was present in neurons of different sizes, and to varying intensities. No relationship was apparent between the staining intensities and morphologically distinguishable types of neurons. In DRG, the type of reactivity was the same from cervical to sacral ganglia. The selected occurrence of GP in specific neurons of the peripheral nervous system in contrast to the ubiquitous occurrence in all astrocytes of the central nervous system may indicate a different role of neuronal glycogen compared to astrocytic glycogen.

Animals↗

PubMed1994

Diversity of ethnic and racial VNTR RFLP fixed-bin frequency distributions.

To examine the impact that intra- and interracial genetic diversities have on VNTR RFLP-fragment-size distributions, a multiracial (East Asian, African American, U.S. Southwest Hispanic, and European Caucasian) and multiethnic (Chinese, Japanese, Korean, and Vietnamese) database has been constructed for the following loci: D1S7, D2S44, D4S139, and D10S28. Homogeneity between samples was examined using the Komologorov-Smirnov two-sample test for RFLP fragment sizes and a log-likelihood test for fixed-bin frequencies with theoretical and Monte Carlo empirical significance levels. Small but significant differences between theoretical and empirical significance-level distributions were observed with both procedures, particularly with the latter. The significance levels of the two types of tests were poorly correlated. Statistically significant differences in fragment-size and fixed-bin distributions were found within and between races, with greater differences occurring between races. Cluster analysis and principal components analysis, using different similarity measures, did not support the hypothesis of greater intra- than interracial diversity, which suggests that ethnic variation can be conservatively estimated by racial variation.

Cluster Analysis↗

PubMed1993

Differentiation of the mammalian retinal pigment epithelium in vitro: influence of presumptive retinal neuroepithelium and head mesenchyme.

The ancestor cells of the pigment epithelium of the mammalian eye are derived from the neuroepithelial cells of the neural plate. They are neurally determined in the process of neurulation but finally decide to follow the pigment cell lineage, whereas the adjacent tissue develops into the neuroretina and the optic stalk. This decision is most probably made in the developmental stage of eye cup formation. The pigment epithelium becomes restricted to the outer leaf of the eye cup and does not encroach on the adjacent neuroepithelial tissues of the internal leaf and the eye stalk. It is therefore supposed to be channelled by a locally confined determinant factor that has not yet been identified. In the present study, development of the mammalian eye and the neural versus pigment cell decision were investigated in mouse embryos. Three approaches were used to discover the source of the putative determinant involved in the process of neuroepithelial decision. First, eye primordia were cultured from stage 11 embryos (0 somites, early neural plate stage, embryonic day 7 1/2-8) to stage 16 embryos (34 somites, neural tube stage, ed 10); this is prior to pigment cell induction. The eye primordia were first cultured in head segments and their natural position. In these experiments, 50% of the ocular neuroepithelia developed along the nerve cell and glial cell lineage. However, the other 50% of the cultured specimens partly developed into pigment epithelia. In these specimens the determinant factors had obviously remained functionally intact in vitro. In the second type of experiment, the eye primordia were also cultured within the head segments, but with the prospective neuroretina selectively removed. This experiment should show whether the inner layer of the eye cup (the prospective neuroretina) is involved in the neuroepithelial lineage decision. In these experiments 90% of the cultured eye primordia failed to develop pigmented cells. The prospective neuroretina was therefore considered as a candidate for the production of an inductive factor. Finally, eye primordia from stage 14-15 embryos (13-29 somites, ed 9-9 1/2) were either transplanted into heterotopic tissues, such as mesenchymal organs, neuroepithelium or heterochronic muscle, or grown as controls in their natural position and tissue environment. In these conditions both transplanted eye primordia and controls bore pigmented epithelium. Hence, the lineage decision, whether to form neural or pigment cell, remained undisturbed in all epitopes tested. On the basis of these experiments, it seemed unlikely that the development of pigment cells was initiated by a mesenchyme-derived factor exclusively produced near the eye vesicle.

Animals↗

PubMed1993

Glycogen phosphorylase activity and immunoreactivity during pre- and postnatal development of rat brain.

Catalytic activity and immunoreactivity of glycogen phosphorylase were studied in pre- and postnatal rat brain. The catalytic activity was assayed in brain homogenates; immunoreactivity was investigated by immunoblot analysis using a monoclonal anti-bovine brain glycogen phosphorylase antibody. The cellular localization and intensity of immunoreactivity were analysed on paraffin-embedded sections utilizing the same monoclonal antibody. The catalytic activity increased 10-fold from embryonic day 16 to adult; immunoreactivity became detectable on embryonic day 16 and increased in intensity as the enzyme activity rose to adult values. The first cellular elements to be stained immunohistochemically were ependymal cells lining the ventricles, ependymal cells of the choroid plexus, meningeal cells and a selected population of neurons in the brain stem. The immunoreactivity of plexus cells and meningeal cells was reduced or absent in the adult rat brain. The earliest appearance of glycogen phosphorylase immunoreactivity in astroglial cells was seen at postnatal day 9 in the hippocampus. The staining pattern of the adult brain was reached at day 22 post partum. The developmental changes in glycogen deposition and in glycogen phophorylase activity and immunoreactivity may indicate a variable physiological role of glycogen metabolism for different cell types in the pre- and postnatal periods.

Animals↗

PubMed1992

Development of membrane currents in mammalian neuroventricular cells from the early neural tube stage in vitro: aspects of the neuronal lineage.

Neuroepithelial cells from the murine brain anlage at the early neural tube stage (embryonic day 9 1/2, stage 15) were cultured. Their morphology and the development of membrane currents were studied during 2 weeks in culture. Immediately after dissociation the cells were equal in shape and no morphological or ultrastructural differences were evident. Patch-clamp measurements within the first 2 h, however, showed different membrane properties. Either sodium inward currents or potassium outward currents were observed in these undifferentiated cells, but no combined inward and outward currents were found. This would mean that some of the neuroventricular cells, but obviously not all of them, display neuronal membrane properties (sodium currents) in the immediate post neural plate stage. After 1 day, developing neurons could be identified morphologically by neurotubuli and process formation. The transformation of these cells into neurons was electrophysiologically characterized by an increasing sodium channel density and the expression of various kinds of potassium channels. After 4 days the vast majority of the neurons was electrically excitable, i.e. they could generate action potentials. The standard electrical profile at this time was characterized by a sodium inward current followed by a delayed potassium outward current. In the following days the complexity of membrane currents increased in some neurons by the emergence of transient potassium currents. After 2 weeks in culture different neuronal phenotypes could be identified.

Animals↗

PubMed1992

Neuronal ectopia in tiger retina.

Ocular pathology in a ten week-old tiger is described. In the retinae of both glaucomatous eyes, venous congestion and scattered hemorrhages were observed; rare perivascular infiltrates were seen. The basal lamina of the inner limiting membrane was considerably thickened, and serous exudates were widely distributed within the vitreous body. The retina was studied with a series of specific antibodies. Müller (glial) cells were well developed and could be immuno-labelled by antibodies against both vimentin and glial fibrillary protein (GFAP). Neurofilament-specific antibodies revealed the presence of ganglion and horizontal cells, and of a nerve fibre layer which was unusually distant from the inner limiting membrane. Within both plexiform layers, scattered neuronal cells were found. The most important finding was the presence of cells between the nerve fibre layer and the inner limiting membrane, which could be immuno-labelled by neuron-specific antibodies, and which expressed thy typical morphology of migrating neuroblasts. It is suggested that this neuronal ectopia might be due to an inflammatory related reactive change in Müller cells which, in turn, might have lost their orderly guiding function for migrating neuroblasts.

Animals↗

PubMed1991

Generation of developmental patterns in the neuroepithelium of the developing mammalian eye: the pigment epithelium of the eye.

Culture experiments with eye anlages of mouse embryos were performed to study developmental traits of the neuroepithelial cells of the prospective pigment epithelium in the eye anlage of pigmented mice. Between the neural plate stage on embryonic day 8 (ED 8, developmental stage 12) and the neural tube stage on embryonic day 9 1/2 (stage 15), the cultured neuroepithelium of the eye generated neurons and glia, identified by morphological and immunocytochemical evidence, but no pigmented cells. In contrast, eye anlages did produce pigment epithelium when cultured in their natural position in a head tissue fragment. A minority of developing neurons displayed tyrosine hydroxylase immunoreactivity, whereas GABAergic, serotoninergic and substance P-ergic neurons, which are common in the mature neuroretina, were not observed. When neuroepithelial cells from embryonic eyes older than stage 15 (ED 9 1/2) were cultured, they differentiated into pigment cells but not into nerve cells or glia. This developmental sequence indicates that the pigment cells derive from the neural lineage. Pigment cell fate dominates over the neural fate beginning at about stage 15 (ED 9 1/2-10). That is at least 2 days before the pigment cell phenotype becomes apparent in vivo (ED 11 1/2-12).

Animals↗

PubMed1990

Generation of GABA-synthesizing nerve cells cultured from embryonic cortex cerebri of mice with and without cell-to-cell contacts.

Neuroblasts, growing from cerebral cortices of embryonic mice, Theiler stages 16, 19, 20, 21, 23 and 24 (embryonic days (ed) 10, 11 1/2, 12, 13, 15 and 16) were cultured in plasma clot and serum-containing MEM-medium in whole-mount cultures, suspension cultures or single-cell cultures. In whole-mount cultures, cell connections were preserved, allowing continuity of cell interactions in vivo and in vitro. In suspension cultures cell adherences and contacts were interrupted by the dissociation procedure. However, contacts re-establish when cells re-aggregate. In single-cell cultures, neuroblasts were cultured without cell-to-cell contacts, and were deprived of potentially mediating cell interactions. Individual features of these cells supposedly reflected both the effect of the medium-derived environment and the state of their intrinsic program at the time of culturing. The neuroblasts' potential for differentiation into GABAergic neurons was studied in all three kinds of culture. GABAergic neurons developed in both tissue samples and suspension cultures, in small numbers from 11 1/2-day-old embryos (stage 19), but in increasing numbers in cortices of advanced ages. GABA immuno-reactivity starts at day 3 in vitro and persists throughout the whole culture period of up to 26 days. Neuroblasts developed in sufficient numbers without cell-to-cell contacts at the earliest in cultures from 12-day-old embryos (stage 20). At that time a few nerve cells expressed GABA after 3 days in vitro. Immunoreactivity increased and persisted until at least day 9. These results indicate that the GABAergic phenotype is expressed irrespective of whether physical cell-to-cell contacts are present or not. Moreover, differences are apparent in the intrinsic program of neuroepithelial cells prior to their display in vivo.

Animals↗

PubMed1989

In vitro experiments on neuronal and glial cell lineages among the ventricular cells of the mouse neural plate.

The proliferative ventricular cells of the early neural plate of the mouse are generally assumed to be pluripotent and equivalent to one another in their developmental capability. Ventricular cells from the rostral parts of the neural plates of mice (Theiler stages 11 and 12, embryonic days 71/2 and 8) were studied in tissue culture with respect to their potential to give rise to neurons or glial cells, or both. Autoradiographic and immunohistochemical analyses showed that ventricular cells developing into neuronal phenotypes stopped proliferating immediately upon transfer to cell culture. Using polyclonal anti-GFAP antibodies, a small proportion of immunoreactive cells could be detected after 4 days of culture. These cells retained their proliferative activity, displayed morphological characteristics of radial glial cells, and may have either developed from specific glial progenitor cells or have been induced to proceed along the glial differentiation pathway at the beginning of culture. Therefore, two distinct types of progenitor cells, committed either to neuronal or glial lineages, appear to co-exist among the cultured neural plate ventricular cells.

Animals↗