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A Probst

Publications and source records attributed to A Probst.

At least 55 records · Page 3Linked to original sources
PubMed1988

Differential modification of muscarinic cholinergic receptors in the hippocampus of patients with Alzheimer's disease: an autoradiographic study.

We have used quantitative light microscopic autoradiographic techniques to analyze changes in muscarinic cholinergic receptors in the hippocampus in Alzheimer type dementia (ATD). The density and distribution of muscarinic cholinergic receptors has been correlated with the density of neurons, neuritic plaques and neurofibrillary tangles in the CA1 subfield of the hippocampus of control and ATD patients. The number of pyramidal cells per mm2 in the CA1 sector was significantly decreased in ATD cases as compared to controls, although there were large variations among cases. The most marked reductions in cell counts were observed in patients with a history of profound dementia. The densities of muscarinic receptors, as well as the proportions of M1 and M2 subtypes, in the CA1 sector and dentate gyrus were not significantly different between ATD and old non-demented patients. Neuritic plaques, even in high numbers, did not affect the density of muscarinic receptors; moreover, the densities of receptors over the neuritic plaques did not differ from the surrounding neuropil. However, in some ATD cases there was a marked decrease in the concentration of these receptors in the CA1 sector and subiculum, with no change in the proportions of muscarinic receptor sybtypes. These patients exhibited frequent extracellular remnants of neurofibrillary tangles (ghost tangles), but scarce neuritic plaques, and were those showing severe losses of pyramidal cells. There was a significant positive correlation between the total concentration of muscarinic receptors in the CA1 and the density of pyramidal cells, suggesting that decreases in receptor concentration result from a severe neuronal loss. We observed that the ratio of muscarinic receptors per pyramidal cell was significantly increased in ATD patients. This might indicate a possible up-regulatory mechanism for muscarinic receptors in the population of remaining neurons in ATD However, decreases of receptor numbers following severe neuronal fall out suggest that compensatory mechanisms are no longer possible in such cases. The question is raised whether these differences between cases reflect different diseases or different stages of the same disease.

Aged↗
PubMed1988

Visualization of a novel serotonin recognition site (5-HT1D) in the human brain by autoradiography.

The localization of a novel serotonin (5-hydroxytryptamine, 5-HT) recognition site named 5-HT1D was studied by autoradiography in human postmortem brain material. Serotonin-1 sites were labeled with [3H]5-HT. The different subpopulations of 5-HT1 sites were investigated by the use of unlabeled selective compounds. 8-OH-DPAT (8-hydroxy-2-[N,N-di-n-propyl-amino]tetralin) was used to block [3H]5-HT binding to 5-HT1A, the beta-blocker (-)-21 009 (4-[3-ter-butyl-amino-2-hydroxy-propoxy]indol-2-carbonic acid isopropyl ester) to 5-HT1B and the ergoline mesulergine to 5-HT1C recognition sites. 5-HT1D sites were defined as the binding sites remaining when both 8-OH-DPAT and mesulergine were added to the incubation medium. Under these conditions, 5-HT1D sites represented a high proportion of total [3H]5-HT binding sites in the basal ganglia and substantia nigra. Lower proportions were observed in other brain areas such as the hippocampal formation and raphé nuclei. 5-HT1D sites thus represent the majority of 5-HT1 binding sites in the striatonigral pathway in man. This localization suggests an involvement of these sites in the mediation of serotoninergic mechanisms in basal ganglia functions and a possible role in brain diseases where these areas are known to be involved.

Autoradiography↗
PubMed1988

Beta-adrenergic receptor mediated release of tissue plasminogen activator in anaesthetized dogs.

Drugs like epinephrine or isoproterenol can enhance fibrinolytic activity of blood. It is still a matter of debate whether this effect can be totally or only partially blocked by beta-receptor blockers. We have developed a dog model for ex vivo measurement of the fibrinolytic activity using a spectrophotometric assay employing human plasminogen, chromogenic plasmin substrate and human fibrinogen-BrCN digests for the stimulation of t-PA. After i.v. administration of isoproterenol the fibrinolytic activity increased, but this could be seen only in the presence of fibrinogen-BrCN digest in the test system. This suggests that isoproterenol caused higher levels of dog t-PA. Pretreatment with the beta-blocker propranolol completely blocked the increase in t-PA.

Anesthesia↗
PubMed1988

Identification of a 5-HT1 recognition site in human brain membranes different from 5-HT1A, 5-HT1B and 5-HT1C sites.

In human caudate and cortex membranes, [3H]serotonin ([3H]5-HT) labels 5-HT1A and 5-HT1C recognition sites which show nanomolar affinity for 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)-tetralin) and mesulergine respectively, whereas no 5-HT1B binding could be identified. However, the majority of the sites labelled by [3H]5-HT (greater than or equal to 60% in cortex, 90% in caudate) are different from 5-HT1A, 5-HT1B and 5-HT1C sites. Competition experiments were performed in human caudate membranes incubated with [3H]5-HT in the presence of 100 nM 8-OH-DPAT and 100 nM mesulergine. Under those conditions, [3H]5-HT labelled an apparently homogeneous population of 5-HT1-like sites which display nanomolar affinity for tryptamines (5-carboxamido-tryptamine, (5-CT) greater than 5-HT greater than or equal to 5-methoxytryptamine (5-MeOT) greater than tryptamine) and some ergolines (metergoline greater than methysergide). In contrast, these sites showed low affinity for drugs with high affinity and/or selectivity for 5-HT1A (8-OH-DPAT, buspirone), 5-HT1B (21-009, RU 24969), 5-HT1C (mesulergine, mianserin) and 5-HT2 sites (ketanserin, cinanserin). The pharmacological profile of these sites is different from that of 5-HT1A, 5-HT1B, 5-HT1C, 5-HT2 and 5-HT3 sites but is consistent with the pharmacology of a 5-HT1-like receptor. It is very similar to that of the 5-HT1D site recently described in bovine brain by Heuring and Peroutka.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1988

Mapping dopamine receptors in the human brain.

We have investigated the anatomic localization of dopamine D1 and D2 receptors in the human brain using selective high affinity ligands for both types of dopamine receptors and the technique of receptor autoradiography. Dopamine D1 receptors were labeled in postmortem human brain tissue sections using the antagonist [3H]SCH 23390. Dopamine D2 receptors were labeled in consecutive tissue sections using the agonist [3H]205-502 and the antagonist [3H]spiroperidol. D1 and D2 dopamine receptors presented a heterogeneous distribution in the human brain. The highest concentrations of both D1 and D2 receptors were found in parts of the basal ganglia, particularly the nucleus caudatus and putamen. Lower concentrations were seen in other areas for example, the lateral globus pallidus was enriched in D2 receptors and the medial globus pallidus in D1 receptors. The substantia nigra contained intermediate densities of both D1 and D2, D1 receptors being present in higher concentrations. Dopamine D1 receptors were also localized in areas outside of the basal ganglia, particularly in the neocortex, amygdala and hippocampal formation. Dopamine D2 receptors were also present in areas outside of the basal ganglia, the most significant densities being found in the hippocampal formation. We observed a marked age-dependent decline in the density of D1 receptors during the first decades of life. In contrast, D2 receptor concentrations appeared to be unaltered with age. The distribution and densities of dopamine receptors were examined in 12 cases of Parkinson's disease and compared to a control adult population. No significant differences in density and distribution were seen for either D1 nor D2 receptors.

Adolescent↗
PubMed1988

Somatostatin-like immunoreactivity in non-pyramidal neurons of the human entorhinal region.

The distribution of somatostatin-immunoreactive cells and processes throughout the human entorhinal region and subjacent white matter was examined either by the unlabelled antibody-enzyme method or by the avidin-biotin method. The brain slices were obtained at autopsy with a short post-mortem delay. The majority of somatostatin immunoreactive nerve cells was found in the inner principal layer and subjacent white matter. In addition, individually scattered immunoreactive neurons were observed in both the outer principal layer and lamina dissecans. The immunoreactive perikarya varied in shape and ranged in size from 10 to 30 micron. Without exception the neurons could be classified as belonging to the group of non-pyramidal neurons. Each neuron gave rise to a few thick dendrites and a thin axon with a beaded appearance. In the adult human brain, the pattern formed by lipofuscin granules deposited in the nerve cells can be considered characteristic for the type of the neuron. Therefore, immunoreactive perikarya were documented, destained of chromogen and restained to demonstrate lipofuscin pigment and basophilic substance. It became evident from these studies that the previously immunoreactive cells were characterized by a large rounded and eccentrically located nucleus, sparse basophilic substance and, in most cases, a lack of lipofuscin granules. A few of the immunoreactive cells were laden with coarse pigment granules. The findings permit classification of entorhinal somatostatin-immunoreactive neurons as either non-pigmented or pigment-laden non-pyramidal neurons.

Aged↗
PubMed1988

Somatostatin-14-like immunoreactive neurons and fibres in the human olfactory bulb.

This study describes the morphological features and the distribution pattern of neurons in the human olfactory bulb which are immunoreactive for an antiserum against the neuropeptide somatostatin-14. Immunoreactive nerve cell bodies were mainly found in the white matter surrounding the cell clusters of the anterior olfactory nucleus. Some immunoreactive neurons were also found scattered throughout the anterior olfactory nucleus and the deeper parts of the inner granule cell layer. Only a few immunoreactive neurons were localized in the glomerular layer and the outer granule cell layer. Immunoreactive fibres were found in all layers of the olfactory bulb. In addition, an impressive number of coiled and kinked immunoreactive fibres were localized within the anterior olfactory nucleus forming a dense plexus. Accumulations of twisted and coiled branches of immunoreactive fibres were rarely found either surrounding or within the olfactory glomerula. The characteristics of somatostatin-14 immunoreactive neurons as seen in the combined pigment-Nissl preparation were studied after decolourizing the chromogen and restaining the preparations with aldehydefuchsin in order to demonstrate the lipofuscin pigment and gallocyanin chrome alum for Nissl material. About 90% of the immunoreactive neurons studied in this manner turned out to be devoid of lipofuscin granules. The remaining 10% displayed different patterns of pigmentation. These findings suggest the presence of different types of somatostatin-14-like immunoreactive neurons in the olfactory bulb of the human adult.

Adult↗
PubMed1988

Progressive supranuclear palsy: extensive neuropil threads in addition to neurofibrillary tangles. Very similar antigenicity of subcortical neuronal pathology in progressive supranuclear palsy and Alzheimer's disease.

Light microscopic immunohistochemical investigations were performed on neurofibrillary tangles (NFT) in four histologically confirmed cases of Alzheimer's disease (AD) and in five patients with a progressive supranuclear palsy (PSP). The antibody panel included antisera to the neuronal microtubule-associated protein, tau, and to isolated paired helical filaments (PHF), as well as mouse monoclonal antibodies (MAbs) to phosphorylated epitopes on high and medium molecular weight neurofilament subunits (RT97 and BF10, respectively). Paraffin sections were also impregnated with the Gallyas silver method, which specifically stains tangles and cortical neuropil threads in AD, but does not stain normal neurofilaments. All tangles in PSP and AD showed consistent immunostaining with antibodies to tau protein and isolated PHF, regardless of their localization. MAbs RT97 and BF10, however, did not stain or only weakly stained, subcortical tangles in PSP and AD, whereas most cortical NFT in AD were intensely immunostained. All tangles in PSP were as heavily impregnated with Gallyas as they were in AD. Furthermore there were extensive networks of Gallyas-positive, tau- and PHF-immunoreactive neurites in subcortical gray areas containing NFT, and bundles of positive axons in white matter tracts interconnecting subcortical nuclei of PSP. Our studies indicate a much more extensive disruption of fibrillar proteins in PSP subcortical neurons than previously reported. They furthermore indicate a very similar antigenic profile of NFT in PSP and AD, as far as subcortical neurons are concerned.

Aged↗
PubMed1988

Regional distribution of the expression of a human stimulatory GTP-binding protein alpha-subunit in the human brain studied by in situ hybridization.

Using a cDNA probe complementary to an mRNA coding for the alpha-subunit of a human GTP-binding protein that stimulates adenylate cyclase we have studied its regional distribution in human brain by in situ hybridization histochemistry. The specificity of the hybridization signal was examined by using a labelled sense probe and RNase treatment. Gs alpha transcripts presented a widespread but heterogeneous distribution in human brain postmortem tissues. The cell bodies of the granular layer of the cerebellum were the most heavily labelled cells in all the cases examined. High levels of hybridization were also seen in the pyramidal cell layer of the hippocampus and over the cell bodies of the granule cells of the dentate gyrus. Several cortical regions also presented high levels of hybridization. Another area rich in the Gs alpha mRNA was the hypothalamus. The caudate and putamen nuclei presented intermediate levels while the globus pallidus, the thalamus, the midbrain and the brainstem presented only very low levels of hybridization. This distribution differs from the known distribution of adenylate cyclase activity and other GTP-binding proteins, and could indicate that this particular Gs alpha clone codes for a subset of the alpha-subunit of the Gs protein family.

Adenylyl Cyclases↗
PubMed1988

Benzodiazepine receptor sites in the human brain: autoradiographic mapping.

Receptor autoradiography was used to localize and quantify the distribution of benzodiazepine receptor sites in human post mortem materials using [3H]flunitrazepam. The distribution and density of these sites was analysed in the brains of 21 patients dying without reported neurological disease. The distribution of benzodiazepine receptors in the human brain was found to be comparable from case to case although differences in the density occurred among the brains examined. No influence of the post mortem delay, age, gender or pre mortem drug treatment on the distribution and densities was observed in our series. The highest densities of benzodiazepine receptors in human brain were localized in cortical and hippocampal areas, nucleus accumbens, amygdala and mammillary bodies. Intermediate densities were found in the basal ganglia and thalamic and hypothalamic nuclei. [3H]Flunitrazepam binding was low in the brainstem nuclei and very low in white matter. The triazolopyridazine Cl 218872, reported to differentiate between type I and type II benzodiazepine receptor sites, exhibited regional differences in affinity when used to block [3H]flunitrazepam binding. Benzodiazepine receptors in the cerebellar cortex were more sensitive to this compound than those in the dentate gyrus of the hippocampus and the tuberal nuclei of the hypothalamus. An enrichment in the concentration of type I benzodiazepine receptor Cl 218872-sensitive sites was observed in motor areas as compared to structures of the limbic system. The addition of GABA to the incubation medium resulted in an increase of [3H]flunitrazepam binding, suggesting the coupling of these sites to a GABAA receptor. The increase in binding was directly proportional to the density of benzodiazepine receptors but unrelated to the density of high-affinity GABAA sites. The distribution of benzodiazepine receptor sites in the human brain compares well with that previously described in the rat brain. The high densities of receptors localized in the limbic system and in the cortical areas suggest that the effects of benzodiazepines are mediated through an interaction with the sites we have visualized in these anatomical structures. Our results provide a detailed map of the distribution of benzodiazepine receptors and a basis for the understanding of pharmacological effects of these drugs in humans and for future studies of modifications of these receptors in neurological and neuropsychiatric conditions in humans.

Aged↗
PubMed1988

Autoradiography of antidepressant binding sites in the human brain: localization using [3H]imipramine and [3H]paroxetine.

[3H]Imipramine and [3H]paroxetine were used to label sites associated with serotonin uptake mechanisms in post-mortem brain tissue from control subjects. The anatomical localization of these sites was examined by autoradiography and densities measured by microdensitometry. We found [3H]imipramine binding to increase with age in the cortex and amygdala, but to be independent of gender and post-mortem delay. Preliminary results indicate that the binding of both [3H]imipramine and [3H]paroxetine is diminished in the brain of patients treated with imipramine. The distribution of [3H]imipramine and [3H]paroxetine high-affinity binding sites was very similar, and correlated well with the distribution of serotonergic presynaptic markers in the brain. The highest densities of binding sites were found in the raphé nuclei and the midline thalamic nuclei. Other structures presenting high levels of binding were the substantia nigra, nucleus interpeduncularis, locus coeruleus, nucleus nervi hypoglossi, nucleus nervi facialis, mammillary bodies and other parts of the hypothalamus. In contrast, regions such as the neocortex, hippocampus, amygdala and cerebellum showed low densities of [3H]imipramine and [3H]paroxetine binding sites. This distribution seems to indicate that the ascending serotonergic pathways are the main site of action of antidepressants.

Aged↗
PubMed1988

Receptors in human brain diseases: a use for receptor autoradiography in neuropathology.

The application of the technique of in vitro receptor autoradiography to the study of neurotransmitter receptor alterations associated with human brain diseases is reviewed. Focus is made on receptor alterations in Parkinson's disease and Senile Dementia. Different types of modifications have been found. The most important are 1) receptor changes related to a specific neuronal loss; 2) receptor regulation associated with modifications of presynaptic input; 3) receptor changes which cannot directly be related to neuronal loss or presynaptic changes. The possible value as a diagnostic tool and the utility of receptor autoradiography in neuropathology is discussed.

Autoradiography↗
PubMed1987

Visualization of adenosine A1 receptors in the human and the guinea-pig kidney.

Adenosine A1 receptors were localized in sections of human and guinea-pig kidney with quantitative receptor autoradiography and [3H]cyclohexyladenosine [( 3H]CHA) used as ligand. The binding sites had the characteristics of an A1 receptor. In the human kidney a high density of receptor sites was measured over the glomeruli. In the guinea-pig kidney the receptor sites were localized in the inner and outer medulla although a low density of binding was also seen over the glomeruli. The functional significance of the findings is discussed.

Adenosine↗
PubMed1987

Distinct topographical localisation of two somatostatin receptor subpopulations in the human cortex.

The use of two different radioligands, [125I]Leu8, D-Tryp22,Tyr25-somatostatin-28 and the stable somatostatin octapeptide analog [125I]204-090, D-Phe-Cys[125I]Tyr-D-Trp-Lys-Thr-Cys-Thr(ol), allowed to differentiate between two somatostatin receptor subpopulations in the human cortex. In homogenates, octapeptide somatostatin analogs displaced only part of the somatostatin-28 radioligand with high affinity. Autoradiography showed that the receptor subpopulation labelled with [125I]204-090, which we named SS1, was preferentially localized in layers V and VI, whereas the subpopulation having low affinity for somatostatin octapeptides (named SS2), measured with somatostatin-28 radioligand, was concentrated in the superficial cortical layers (I-IV) and particularly enriched in parts of lamina IV.

Aged↗
PubMed1987

On the distribution of cholecystokinin receptor binding sites in the human brain: an autoradiographic study.

Cholecystokinin (CCK) binding sites were localized by in vitro autoradiography in human postmortem brain materials from 12 patients without reported neurological diseases using [125I]Bolton-Hunter CCK octapeptide (BHCCK-8) as a ligand. The pharmacological characteristics of BHCCK-8 binding to mounted tissue sections were comparable to those previously reported in the rat. CCK-8 being the most potent displacer, followed by caerulein, CCK-4, and gastrin I. The distribution of BHCCK-8 binding sites was heterogeneous. These sites were highly concentrated in a limited number of gray matter areas and nuclei. The highest binding densities were seen in the glomerular and external plexiform layers of the olfactory bulb. BHCCK-8 binding sites were also enriched in the neocortex, where they presented a laminar distribution with low levels in lamina I, moderate concentration in laminae II to IV, high density in lamina V, and low levels in lamina VI. A different laminar distribution was seen in the visual cortex, where a low receptor density was observed in lamina IV but higher density in laminae II and VI. In the basal ganglia the nucleus accumbens, caudatus, and the putamen presented moderate to high densities of binding sites, while the globus pallidus lacked sites of BHCCK-8 binding. In the limbic system the only area presenting moderate to high density was the amygdaloid complex, particularly in the granular nucleus, while most of the thalamic nuclei were extremely poor or lacked BHCCK-8 binding. The hippocampal formation showed low (CA1-3) to moderate (subiculum) densities. Midbrain areas generally disclosed very low levels of BHCCK-8 binding sites. The pontine gray and the nucleus reticularis tegmenti pontis showed a relatively high density of CCK-8 receptor specific binding. Moderate to very high densities were found in few nuclei of the lower brainstem and spinal cord as the inferior olives and their accessory nuclei, the arcuate nuclei, the striae medullares, the efferent (motor) nucleus of the vagus, and the substantia gelatinosa of the cervical and thoracic spinal cord. These results are discussed in relation to the distribution of endogenous peptide and to the known physiological and pharmacological effects of substances acting on these receptors.

Aged↗
PubMed1987

Alzheimer dementia and Pick's disease: neurofibrillary tangles and Pick bodies are associated with identical phosphorylated neurofilament epitopes.

Sections of formaldehyde-fixed paraffin-embedded cortical and hippocampal brain tissue from five cases with senile dementia of Alzheimer type (SDAT) and five cases with Pick's disease (PD) were immunostained with the monoclonal antibodies (mabs) 147, RT 97, BF 10 and 8D8 with and without pretreatment with alkaline phosphatase (AP) or trypsin (Tr). The mabs 147, RT 97 and BF 10 had previously been demonstrated to bind exclusively to phosphorylated epitopes of neurofilament proteins, while mab 8D8 is shown in this report to bind mainly, but not exclusively, to phosphorylated neurofilament epitopes. The mabs RT 97, BF 10 and 8D8, but not 147 stain most, if not all, Pick bodies (PB) and Alzheimer neurofibrillary tangles (NFT). When sections are pretreated with AP or Tr the immunostaining with mab BF 10 is very resistent in both PB and NFT. This resistance of PB and NFT is in contrast to the reduced staining of axons and of swollen cells in PD by the same enzymatic pretreatment. Immunostaining with mab RT 97 of PB and NFT is reduced moderately by AP and considerably by Tr. Only when stained with mab 8D8 is there a discrepancy between PB and NFT in their reaction to the pretreatment with AP: NFT staining with mab 8D8 is not affected, while that of PB is abolished. Thus, in spite of their different ultrastructure, PB and NFT are very similar immunocytochemically and in the accessibility of their phosphorylated epitopes to enzymatic treatment.

Alzheimer Disease↗
PubMed1987

A special type of senile plaque, possibly an initial stage.

It is customary to distinguish "primitive", "classic" and "compact" ("burned out") senile plaques in Alzheimer's disease and senile dementia of the Alzheimer type (SDAT). Primitive plaques are characterized by altered neurites without accumulation of amyloid, classic plaques by an amyloid core surrounded by altered neurites and compact plaques by amyloid without pathological neurites. Here we describe a further type of plaque in which no amyloid or obviously altered neurites could be found by light microscopy with appropriate stains. This type of plaque was found mainly in the lateral entorhinal region and could be recognized by a slightly more intense staining and an altered texture of the neuropil in a spherical area having the same size as an early or mature plaque (100-150 microns in diameter). In non-serial paraffin sections (3-4 microns thick), a dark, silver-positive cell measuring 10-12 microns in diameter was found in the center of 49 out of 400 such plaques (about 12%), which is the expected frequency if one assumes that every plaque contains such a cell and measures itself about 125 microns. In fact, the reconstruction of 15 plaques (from four different patients) by means of serial sections demonstrated the presence of a central cell in each of them suggesting that this cell is an essential component of this plaque type. The central cell did not react with antibodies against cells of the mononuclear phagocyte lineage, such as alpha-1-antichymotrypsin, alpha-1-antitrypsin, leucocyte common antigen and lysozyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗