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K Brauer

Publications and source records attributed to K Brauer.

At least 55 records · Page 3Linked to original sources
PubMed1995

Digoxigenylated primary antibodies for sensitive dual-peroxidase labelling of neural markers.

This study extends the application of the digoxigenin-anti-digoxigenin (DIG) technique to immunocytochemistry by using digoxigenin-tagged primary antibodies. Certain features of this technique when applied to non-radioactive in situ hybridization, such as the absence of endogeneous digoxigenin immunoreactivity in animal tissues, seem to be advantageous also for its application to immunocytochemistry. Thus, the present work is focused on dual-peroxidase staining experiments based on digoxigenylated antibodies directed against glial fibrillary acidic protein, parvalbumin, and calbindin, in a straightforward combination with conventional cytochemical methods. The protocols include the concomitant detection of two antigens, for which only primary antibodies from one animal species are available, with differently haptenized antibodies (e.g., biotinylated anti-calbindin and digoxigenylated anti-parvalbumin). The versatility of the DIG technique is exemplified by the combination of lectin and immunocytochemical procedures for the detection of astrocytes and microglia, and the simultaneous visualization of perineuronal nets and parvalbumin-containing neurons in the rat brain.

Animals↗
PubMed1994

Cortical areas are revealed by distribution patterns of proteoglycan components and parvalbumin in the Mongolian gerbil and rat.

Cortical areas in rodents have been basically characterized by its cytoarchitecture, connectivity or by physiological parameters. In this study we show that they are revealed by distribution patterns of proteoglycans and parvalbumin-immunoreactivity. Brains of young adult Mongolian gerbils (Meriones unguiculatus) and Wistar rats were cut into series of transversal sections. Proteoglycan components were detected using the N-acetylgalactosamine binding Wisteria floribunda agglutinin (WFA) and antibodies against chondroitin sulphate proteoglycan (CSPG). Differences between cortical areas were found to exist with regard to the occurrence and the density of perineuronal nets, but were also expressed in varying staining intensities for WFA and CSPG of the neuropil. Primary neocortical areas (somatosensory, auditory, visual cortex) were characterized by an intense neuropil staining in layer IV and the upper part of layer VI. Using the same methods strong labelling was also typical of the neuropil in the retrosplenial cortex, of layer Ia in the prepiriform cortex and the hippocampal CA3 field. In tangential sections cut from gerbil cortical hemispheres, some of the heavily lectin-stained cortical areas were sharply delineated from adjacent faintly labelled regions, others showed more diffuse borders. In the rat, the area-specific staining for WFA was less clearly expressed than in the gerbil. Immunocytochemistry of the calcium-binding protein parvalbumin in alternate sections showed labelling patterns of neuropil which resembled those of WFA-binding and CSPG-immunoreactivity in the entire neocortex and hippocampus. From these results it can be concluded that functional peculiarities of cortical fields may not only be determined by neuronal network parameters but also by the spatial arrangement of extracellular matrix proteoglycans.

Animals↗
PubMed1994

Digoxigenin-tagged anti-GFAP and multiple labelling of human glia, vessels and beta-amyloid.

Cytochemical procedures for the combined demonstration of astroglia, microglia, blood vessels and beta-amyloid in the human brain were developed. These multiple label experiments include the first adaptation of the digoxigenin-antidigoxigenin technique to immunocytochemistry by using digoxigenylated antibodies directed against the glial fibrillary acidic protein and its visualization in astrocytes with an antidigoxigenin-peroxidase conjugate and diaminobenzidine as chromogen. Furthermore, the specific labelling of microglial cells was performed with the novel enhanced polymer one-step staining technique, non-interfering with conventional detection systems. The demonstration of spatial relationships between glial and vascular components in normal tissue and their alterations, e.g. in Alzheimer's disease, might provide insights into the time course and localization of pathological events.

Alzheimer Disease↗
PubMed1994

Chondroitin sulfate proteoglycan-immunoreactivity of lectin-labeled perineuronal nets around parvalbumin-containing neurons.

Perineuronal nets represent highly specialized glial and glia-associated structures. In this study, a triple fluorescence labeling of chondroitin sulfate proteoglycan-immunoreactive (CSPG-ir) and N-acetylgalactosamine (GalNac)-specific plant lectin Wisteria floribunda agglutinin (WFA) binding net components as well as parvalbumin-immunoreactivity (-ir) was performed. It was shown in the rat cortex, that the same nets frequently surrounding parvalbumin-ir neurons are stained by CSPG-ir as well as by the lectin binding method.

Animals↗
PubMed1994

Mapping of perineuronal nets in the rat brain stained by colloidal iron hydroxide histochemistry and lectin cytochemistry.

Net-like structures, visualized with the Golgi technique and several histochemical and immunocytochemical methods, have been described to ensheath somata, parts of dendrites and axon initial segments of various types of neurons. The origin and function of these perineuronal nets have been controversially discussed. Recently, it was confirmed that they are glia-associated. In the present study such perineuronal nets were demonstrated by using colloidal iron hydroxide staining for detection of polyanionic components and the plant lectins Vicia villosa agglutinin and Wisteria floribunda agglutinin with affinity for N-acetylgalactosamine. This paper shows their distribution patterns and the occurrence of regional specialization of these nets which might provide a basis to suggest functional implications of these structures. Perineuronal nets were found in more than 100 brain regions, such as neocortex, hippocampus, piriform cortex, basal forebrain complex, dorsal lateral septal nucleus, lateral hypothalamic area, reticular thalamic nucleus, zona incerta, deep parts of superior and inferior colliculus, red nucleus, substantia nigra, some tegmental nuclei, cerebellar nuclei, dorsal raphe and cuneiform nuclei, central gray, trochlear nucleus, pontine and medullar reticular nuclei, superior olivary nucleus and vestibular nuclei. Neurons enwrapped by perineuronal nets not only differ in morphology but also in transmitter content. In neocortical and hippocampal regions there occurs a much higher number of perineuronal nets ensheathing non-pyramidal cells than in paleocortical structures. Most subcortical regions containing perineuronal nets were found to be integrated in motor functions. The findings are discussed with respect to known electrophysiological data of cell types described in our investigation as net-associated. There are some indications that such cells may represent fast firing types.

Animals↗
PubMed1994

Projection of non-cholinergic basal forebrain neurons ensheathed with perineuronal nets to rat mesocortex.

The existence of non-cholinergic (GABAergic) components in the septo-hippocampal system but also in basal forebrain projections terminating in the olfactory bulb and certain cortical areas has been documented by several authors using retrograde and anterograde tracing techniques. On the other hand, the basal forebrain also contains a high number of mainly parvalbumin-positive neurons ensheathed by a lattice-like matrix of polyanionic proteoglycans forming so-called perineuronal nets of as yet unknown function. By a combination of retrograde tracing using Fluoro-Gold injection into mesocortical areas of rats and staining of perineuronal nets by Wisteria floribunda agglutinin (WFA) the present study describes the projection pattern and distribution of non-cholinergic projection neurons characterized by perineuronal nets in the anterior parts of the basal forebrain complex (medial septal nucleus, nucleus of the diagonal band of Broca, magnocellular preoptic nucleus). After tracer injection into the cingulate cortex labelled net-associated neurons were distributed within the rostrocaudal extension of the basal forebrain complex but were predominantly found in the horizontal limb of the diagonal band of Broca. Retrograde labelling of neurons with perineuronal nets after tracer injection into the retrosplenial cortex was more pronounced in the medial septum. Choline acetyltransferase-immunoreactive (ChAT-ir) projection neurons were in no case associated with perineuronal nets. The results demonstrate that a large portion of the non-cholinergic projection neurons of the basal forebrain are endowed with a specialized microenvironment of proteoglycans and form a strong input system of mesocortical components of the limbic system.

Animals↗
PubMed1993

Distribution of parvalbumin-containing neurons and lectin-binding perineuronal nets in the rat basal forebrain.

In sections of rat brain treated for Wisteria floribunda agglutinin (WFA) labelling the occurrence of parvalbumin (PARV)-, calbindin (CALB)- or choline acetyltransferase (ChAT) immunoreactivity was analyzed in the basal forebrain using dual-peroxidase and double-fluorescence methods. Only PARV-immunoreactive (-ir) neurons were surrounded by WFA-labelled, i.e. N-acetylgalactosamine-containing, perineuronal lattice-like structures known as perineuronal nets. The distribution of these nets and PARV-ir cells in the rat basal forebrain was documented to obtain detailed data on their co-existence. A remarkable diversity in distribution of both markers was observed, as PARV-ir neurons are only associated with nets in the medial septal nucleus, the nuclei of the diagonal band and the magnocellular preoptic nucleus, but not in the ventral pallidum or the substantia innominata/nucleus basalis complex. These differences in the neuronal microenvironment may reflect system-related specializations of neurons within the basal forebrain nuclei.

Animals↗
PubMed1993

Quantitative phylogenetic constancy of cerebellar Purkinje cell morphological complexity.

Golgi-stained material of cerebellar cortices from 17 species was examined by measuring the fractal dimensions of the borders of Purkinje cells, which is a quantitative, objective measure of morphological complexity. Nine species (from birds to man) were chosen for a comparison with ANOVA and no statistically significant differences were found in their fractal dimensions. In contrast, a wide range of differences was found in the membrane areas across species lines. The Sholl coefficient, a measure of branch formation and termination away from the soma, showed no consistent pattern for each cell. We interpret our results as indicating a constancy in morphological cellular complexity of Purkinje cells during late evolutionary time.

Analysis of Variance↗
PubMed1993

Perineuronal nets provide a polyanionic, glia-associated form of microenvironment around certain neurons in many parts of the rat brain.

The nature and function of previously described perineuronal nets are still obscure. In the present study their polyanionic components were demonstrated in the rat brain using colloidal iron hydroxide (CIH) staining. In subcortical regions, such as the red nucleus, cerebellar, and vestibular nuclei, most neurons were ensheathed by CIH-binding material. In the cerebral cortex perineuronal nets were seen around numerous nonpyramidal neurons. Biotinylated hyaluronectin revealed that hyaluronan occurs in perineuronal nets. Two plant lectins [Wisteria floribunda agglutinin (WFA) and Vicia villosa agglutinin (VVA)] with affinity for N-acetylgalactosamine visualized perineuronal nets similar to those rich in anionic components. Glutamic acid decarboxylase (GAD)-immunoreactive synaptic boutons were shown to occupy numerous meshes of perineuronal VVA-positive nets. Electron microscopically, VVA binding sites were scattered throughout perisynaptic profiles, but accumulated at membranes and in the extracellular space except not in synaptic clefts. To investigate the spatial relationship between glial cell processes and perineuronal nets, two astrocytic markers (S100-protein and glutamine synthetase) were visualized at the light and electron microscopic level. Two methods to detect microglia by the use of Griffonia simplicifolia agglutinin (GSA I-B4) and the monoclonal antibody, OX-42, were also applied. Labelled structures forming perineuronal nets were observed with both astrocytic, but not with microglial, markers. It is concluded that perineuronal nets are composed of a specialized type of glia-associated extracellular matrix rich in polyanionic groups and N-acetylgalactosamine. The net-like appearance is due to perisynaptic arrangement of the astrocytic processes and these extracellular components. Similar to the ensheathment of nodes of Ranvier, perineuronal nets may provide a special ion buffering capacity required around various, perhaps highly active, types of neurons.

Acetylgalactosamine↗
PubMed1993

Mechanics of respiratory system in healthy anesthetized humans with emphasis on viscoelastic properties.

The classic model of the respiratory system (RS) is comprised of a Newtonian resistor in series with a capacitor and a viscoelastic unit including a resistor and a capacitor. The flow interruption technique has often been used to study the viscoelastic behavior under constant inspiratory flow rate. To study the viscoelastic behavior of the RS during complete respiratory cycles and to quantify viscoelastic resistance (Rve) and compliance (Cve) under unrestrained conditions, we developed an iterative technique based on a differential equation. We, as others, assumed Rve and Cve to be constant, which concords with volume and flow dependency of model behavior. During inspiration Newtonian resistance (R) was independent of flow and volume. During expiration R increased. Static elastic recoil showed no significant hysteresis. The viscoelastic behavior of the RS was in accordance with the model. The magnitude of Rve was 3.7 +/- 0.7 cmH2O.l-1 x s, i.e., two times R. Cve was 0.23 +/- 0.051 l/cmH2O, i.e., four times static compliance. The viscoelastic time constant, i.e., Cve.Rve, was 0.82 +/- 0.11s. The work dissipated against the viscoelastic system was 0.62 +/- 0.13 cmH2O x 1 for a breath of 0.56 liter, corresponding to 32% of the total energy loss within the RS. Viscoelastic recoil contributed as a driving force during the initial part of expiration.

Adult↗
PubMed1992

Wisteria floribunda agglutinin-labelled nets surround parvalbumin-containing neurons.

Net-like structures surrounding several types of neurones contain glycoconjugates which are detectable by lectins specific for N-acetylgalactosamine. Wisteria floribunda agglutinin (WFA) was introduced as a further marker for the visualization of such perineuronal nets, which were also revealed in regions of the rat brain where these structures could not be clearly demonstrated using other lectins. The WFA-labelled perineuronal nets resembled in detail those which could be visualized using Vicia villosa agglutinin, colloidal iron or hyaluronectin as markers. Furthermore, WFA-stained perineuronal net components appeared to be similar to proteoglycan-immunoreactive structures. Dual-peroxidase experiments and fluorescence double labelling demonstrated that WFA-binding structures frequently ensheath GABAergic neurons containing the calcium-binding protein parvalbumin in the areas investigated.

Animals↗
PubMed1991

Comparative morphometry of Bergmann glial (Golgi epithelial) cells. A Golgi study.

Bergmann glial (Golgi epithelial) cells were Golgi-impregnated in the cerebella of species with great differences in the thickness of the molecular layer, in small African native mouse, rat, rhesus monkey, and man. The thickness of the molecular layer determines the length of the radial Bergmann cell processes. Whereas the overall morphology of the cells was found to be strikingly similar in all species studied, there were great quantitative differences in length and diameter of the stem processes. Species with thick molecular layers (man, monkey) have thicker stem processes than species with short distances between Bergmann glial cell soma and pial surface (rat, mouse). This could mean that larger animals with longer gestation periods allow for prolonged growth of cell volumes. On the other hand, an increase in the diameter of long processes should reduce the cytoplasmic resistance against ionic currents; this would be important when Bergmann glial cells--like retinal Müller cells--would act as "cables" for spatial buffering of potassium ions released by electrically active neurons. By contrast, the fractal dimension--i.e., a quantitative measure of the complexity of the cell's border--of the cell processes was lower in species with long processes. In an age series of rat cells, the fractal dimension is shown to increase slightly up to a very old age.

Animals↗
PubMed1991

Isocapnic high frequency jet ventilation: dead space depends on frequency, inspiratory time and entrainment.

Twelve healthy pigs were ventilated with high frequency jet ventilation via a Mallinckrodt HiLo jet tube. The expired gas was led to a conventional ventilator and CO2 analyzer which were used to measure CO2 elimination. There was no bias flow, so that the jet entrained only expired gas, i.e. rebreathing occurred. Frequency was varied between 2 and 11 Hz and the duration of inspiration, as a fraction of the ventilatory cycle (Ti/Ttot), from 5 to 20%. The minute ventilation, Vjet, delivered by the jet ventilator was adjusted to maintain a constant PaCO2. At 2 Hz and a Ti/Ttot of 5%, Vjet was of the same magnitude as ventilation during conventional intermittent positive pressure ventilation, and the total dead space fraction, VD/VT was 0.32. Both increasing frequency at a constant Ti/Ttot, and increasing Ti/Ttot at a constant frequency, increased VD/VT which was maximal (0.8) at 11 Hz and a Ti/Ttot of 20%. When entrainment was blocked, tidal jet volume had to be greatly increased. The continuous measurement of CO2 elimination was found to be useful for maintaining isocapnia when the jet ventilator setting was changed.

Animals↗
PubMed1991

Morphology of neurons in the rat basal forebrain nuclei: comparison between NADPH-diaphorase histochemistry and immunohistochemistry of glutamic acid decarboxylase, choline acetyltransferase, somatostatin and parvalbumin.

Transversal sections through the basal forebrain of 11 adult male rats were immunostained for glutamic acid decarboxylase (GAD), choline acetyltransferase (ChAT), somatostatin (SOM) and parvalbumin (PARV). Immunohistochemistry of ChAT, PARV, and SOM was combined with histochemistry of NADPH-diaphorase (NADPH-d) to obtain information on the colocalization of various neuroactive substances and this enzyme and to facilitate the recognition of morphological details of double-stained neurons. The distribution patterns of GAD- and PARV-immunoreactive cells were only in part congruent in basal forebrain nuclei in the rat. In the medial septal nucleus (MS) and the vertical limb of the diagonal band (vDB) PARV-immunopositive neurons were homogeneously scattered inside the nucleus, whereas the GAD-immunoreactive cells were much more numerous in the lateral part of this nuclear complex. In the horizontal limb of the diagonal band (hDB) and the nucleus preopticus magnocellularis (NPM), where GAD-immunoreactive cells occurred in high number, only very few cells contained PARV-immunoreaction product. In the substantia innominata-nucleus basalis Meynert complex (SI-NB) and in the ventral pallidum (VP) the neuropil was heavily stained with the GAD-immunoreaction product. The number of GAD-positive cells appeared low in the SI-NB, but much higher in the VP. In this nucleus GAD- and PARV-immunoreactive cells seem to be identical. PARV-positive neurons are very sparse in the SI-NB. Double-staining of PARV-immunoreactivity and NADPH-d was not registered. These nuclei were the only ones in which some cells with SOM-like immunoreactivity were observed. Among ChAT-positive neurons those double-stained with NADPH-d occurred in moderate number, but with obvious regional differences. In MS-vDB and the marginal zone of hDB the two neuron groups were intermingled, but only in the innermost part of the hDB ChAT-single-immunostained cells form aggregates, which were also typical of the zone in the SI-NB that surrounds and infiltrates the globus pallidus (GP). Double-labelled cells were more frequent in the lateral aspect of the NPM and SI-NB. Cells single-stained for NADPH-d were frequent in the MS-vDB along the border toward the lateral septal nuclei, but low in number in the NPM, VP and SI-NB. The functional aspects of the occurrence of GAD-immunoreactive cell aggregates in the lateral preoptic area (LP) and the lateral hypothalamic area (LH) were discussed with special regards to extrinsic GABAergic input in the dorsal SI-NB.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

[Electron microscopic studies on the medial septal nucleus of the rat: neuronal somata and axosomatic contact].

At least 4 categories of neurons were found in this region, whose somata differ in ultrastructural features. 1. Large cells with a broad rim of cytoplasm (nucleus cytoplasm-index; 3.07 +/- 0.67), RER is densely arranged throughout the whole perikaryon. The nuclear invagination index (1.34 +/- 0.19) is low. Few axosomatic contacts are present. 2. Large to medium-sized cells with a broad rim of cytoplasm (nucleus/cytoplasm-index 2.58 +/- 0.36 and 2.08 +/- 0.42). The RER is clustered in voluminious staples. There are differences in the nuclear invagination indices between subpopulations. In large cells it is low (1.36 +/- 0.24), but it is high in medium-sized cells (1.70 +/- 0.5). Axo-somatic contacts are more numerous in this type than in others. 3. Large, medium-sized and small cells with a broad rim of cytoplasm (nucleus/cytoplasm-index; 2.50 +/- 0.32, in large and medium-sized 2.25 +/- 0.5 and 2.24 +/- 0.48 in small cells). Single RER elements tends to be arranged in loops. The cells are characterized by a high nuclear invagination index. It is 1.68 +/- 0.38, in the large cells, 1.56 +/- 0.44 in the medium-sized and 1.55 +/- 0.34 in the small ones. In this neuron category the number of axo-somatic contacts is very low. 4. Medium-sized to small cells with a narrow cytoplasmic rim (nucleus/cytoplasm-index; 1.78 +/- 0.23 and 1.89 +/- 0.39). RER is nearly absent. The nuclear invagination index of medium-sized cells (1.11 +/- 0.07) and of small cells (1.14 +/- 0.12) is lower than in other categories. These cells exhibit a very low number of axo-somatic contacts. Comparison with findings of immunostained cells lead to the conclusion that category 2 corresponds to GABA-ergic and category 3 to cholinergic neurons of the medial septal region.

Animals↗
PubMed1990

[Characterization of the neurons of the basal forebrain complex in the rat: A Nissl- and Golgi impregnation study].

Nissl stained neurons were classified in some nuclei of the basal forebrain complex of the rat (Nc. septi medialis, MS; vertical limb of the nucleus of the diagonal band, vDB; horizontal limb of the nucleus of the diagonal band, hDB; Nc. preopticus magnocellularis, NPM; Substantia innominata, SI; Nc. basalis Meynert, NB). Several types of neurons are coexistent in each of these nuclei. They differ in soma size and shape, but also in their cytoplasmic and nuclear texture. We found three classes of neurons as well in the MS-vDB, as in the hDB and NPM, but five classes in the SI-NB complex. On the basis of these findings some conclusions were drawn regarding the cytoarchitecture of this region, as the demarcation of vDB and hDB and of hDB and NPM. The borderline between vDB and hDB was found to be undefinable in Nissl stained preparations, whereas the NPM is characterized by its high content of giant neurons in cotontrast the adjacent hDB. Additionally, we tried to identify the Nissl stained neurons on the basis of soma features with Golgi impregnated neurons. The daimpregnations of Golgi impregnated neurons enabled us to compare the width of the cytoplasm and the nuclear position of neurons stained after these methods. From the thirteen classes of neurons described in Golgi investigations, 8 were identified in Nissl stained sections through this region of the rat's forebrain.

Animals↗
PubMed1990

Ultrastructure of neurons and their synaptic contacts in the medial septal nucleus of the rat.

The medial septal nucleus of non-experimentally treated albino rats was investigated electron microscopically. According to former light microscopical findings most of the dendrites in this region are spineless but conspicuously varicose. Besides a striking diminution of the packing density of neurotubules inside the varicosities--compared with the narrow portions of varicose dendrites--some organelles like multivesicular bodies, lamellated bodies and cisterns of the smooth endoplasmic reticulum were found to be characteristic of them. Large neuronal somata rich in RER with a broad rim of cytoplasm around the nucleus and numerous lipofuscin-like granules occur. But there are numerous small cells exhibiting a narrow rim of cytoplasm and pourly developed RER, too. At least six classes of synaptic junctions can be distinguished, three of the asymmetric and three of the symmetric type. Most of axo-somatic contacts are of the symmetric type, at the dendrites asymmetric contacts dominate. Presynaptic profiles with large dense-core vesicles form symmetrical contacts with varicose and non-varicose dendritic profiles.

Animals↗