Biomedical subjects

J Saura

Publications and source records attributed to J Saura.

At least 19 recordsLinked to original sources

PubMed2003

Localization of monoamine oxidase A and B and semicarbazide-sensitive amine oxidase in human peripheral tissues.

Monoamine oxidase (MAO) A and B and semicarbazide-sensitive amine oxidase (SSAO) localizations in peripheral human tissues were compared by immunohistochemistry. The primary antibodies used were mouse monoclonal anti-human MAO-A (6G11/E1) and anti-human MAO-B (3F12/G10/2E3) and a rabbit polyclonal anti-bovine SSAO antibody. Immunoreactivities of the samples, obtained from 6 routine autopsy cases, showed different distributions in the tissues studied (heart, lung, duodenum, liver, pancreas, spleen, thyroid gland, adrenal gland and kidney). The relative MAO-A, MAO-B and SSAO distributions indicated a widespread distribution of these enzymes in the human body that is characterized by a matching cellular pattern in only few tissues. These differences suggest that each amine oxidase may play a specific function in, at least some, peripheral tissues.

Journal Article↗

PubMed2001

Cellular localization of monoamine oxidase A and B in human tissues outside of the central nervous system.

We studied the localization of monoamine oxidase (MAO) A and B in human heart, liver, duodenum, blood vessels and kidney by immunohistochemistry. The primary antibodies used were mouse monoclonal anti-human MAO-A (6G11/E1) and anti-human MAO-B (3F12/G10/2E3). Samples were obtained from six routine autopsy cases and fixed in 2% paraformaldehyde. All cardiomyocytes and hepatocytes showed MAO-A and MAO-B immunoreactivity. In the duodenum, both immunoreactivities were present in all cells of the villi, Lieberkühn crypts, muscularis mucosae and muscular layers, whereas Brunner glands were devoid of MAO-A and MAO-B staining. Endothelial cells of lymphatic vessels showed MAO-A but no MAO-B immunoreactivity, whereas arteries and veins presented MAO-A and MAO-B staining in muscular layers and fibroblasts but not in endothelial cells. In the kidney, renal tubuli showed MAO-A and MAO-B immunoreactivities, whereas collecting ducts and the Bowman's capsule showed only MAO-A staining. These data represent the first study of the cellular distribution of MAO-A and MAO-B in these human tissues. They show that both enzymes have a widespread distribution in the human body with a matching pattern in many, but not all tissues, and with strong differences from the pattern of distribution in rodents.

Aged↗

PubMed2001

Neuronal injury-induced expression and release of apolipoprotein E in mixed neuron/glia co-cultures: nuclear factor kappaB inhibitors reduce basal and lesion-induced secretion of apolipoprotein E.

In order to better delineate the intracellular signaling pathways underlying glial apolipoprotein E (apoE) expression and release, we have characterized an in vitro model of induction of glial apoE production induced by neuronal death. Exposure of mixed fetal cortical neuron/glia co-cultures to the neurotoxin N-methyl-D-aspartate results in increased apoE expression and release in a time- and concentration-dependent manner. Increased expression of apoE messenger RNA precedes the increase in intracellular apoE, followed by accumulation of the holoprotein in the culture medium. Neuronal injury induced by N-methyl-D-aspartate is accompanied by a reactive astrogliosis as measured by an increase in glial fibrillary acidic protein messenger RNA and protein at 48 and 72h post-lesion, respectively. A similar microgliosis was observed using the microglial marker ED-1. Neuronal injury-induced glial apoE secretion is attenuated by the nuclear factor kappaB inhibitors, aspirin, Bay 11-7082 and MG-132, suggesting that this transcription factor is involved in both constitutive and induced glial apoE expression. The present data show that up-regulation of apoE is an early event in the glial activation triggered by neurodegeneration in vitro and that activation of nuclear factor kappaB directly or indirectly mediates the increase in apoE expression.

Alzheimer Disease↗

PubMed2000

PU.1 expression in microglia.

The transcription factor PU.1 has a pivotal role in both the generation and function of macrophages. To determine whether PU.1 is also involved in microglial regulation, we investigated its expression following hypoxic-ischemia (HI) brain injury and in the BV-2 microglial cell line. We found that microglia constitutively expressed high levels of PU.1 protein in both their 'resting' and 'activated' states.

Animals↗

PubMed2000

Differential vulnerability of hippocampus, basal ganglia, and prefrontal cortex to long-term NMDA excitotoxicity.

In human brain, nonartherosclerotic calcification is associated with normal aging and several pathological conditions without any clear significance. In all situations, calcification appears predominantly in the basal ganglia, but is also frequent in the hippocampus and cerebral cortex. alpha-Amino-(3-hydroxi-5-methyl-4-isoxazol-4-il)-propionic acid-induced lesion of the globus pallidus is associated in rats with the formation of calcium deposits similar to those observed in the human brain. To determine whether direct neuronal activation may induce calcification, N-methyl-d-aspartate (NMDA) was microinjected in rat hippocampus, globus pallidus, and lateral prefrontal cortex. Two months later, neuronal death was associated with calcium deposits that were characterized in terms of distribution and size. A unique population of deposits was present in the hippocampus and prefrontal cortex, whereas in the globus pallidus two main groups could be differentiated. Calcification was always associated with a significant microglial reaction as shown by the peripheral benzodiazepine receptor autoradiography. Monoamine oxidase B autoradiography, reflecting the astroglial reaction, was also significantly increased. Our results provide evidence that acute NMDA neuronal activation leads with time to calcification associated with a glial reaction and indicate that nonartherosclerotic calcification in the human brain may develop from an acute NMDA receptor activation. A key role of the metabotropic mGluR1 receptor is also suggested.

Animals↗

PubMed2000

Neuroanatomical abnormalities in behaviorally characterized APP(V717F) transgenic mice.

Histological analyses were performed on the brains of APP(V717F) transgenic (Tg)mice previously studied in a battery of behavioral tests. We describe here the regional and age-dependent deposition of amyloid in both heterozygous and homozygous Tg mice. We also report that Tg mice show significant and age-dependent changes in synaptic density measured by synaptophysin immunoreactivity. Surprisingly, a rather marked hippocampal atrophy is observed as early as 3 months of age in Tg mice (20-40%). Statistical analyses revealed that the deficits in object recognition memory are related to the number of amyloid deposits in specific brain regions, whereas deficits in spatial reference and working memory are related to the changes in synaptic density and hippocampal atrophy. Our study suggests that the behavioral deficits observed in Tg mice are only in part related to amyloid deposition, but are also related to neuroanatomical alterations secondary to overexpression of the APP(V717F) transgene and independent of amyloid deposition.

Age Factors↗

PubMed2000

Localization of monoamine oxidase A and B in human pancreas, thyroid, and adrenal glands.

We studied monoamine oxidase (MAO) A and B localization in human pancreas, thyroid gland, and adrenal gland by immunohistochemistry. The primary antibodies used were mouse monoclonal anti-human MAO-A (6G11/E1) and anti-human MAO-B (3F12/G10/2E3). Samples were obtained from six routine autopsy cases and fixed in 2% paraformaldehyde. Exocrine pancreas showed a widespread distribution of MAO-A, whereas MAO-B was present only in centroacinar cells and epithelial cells of pancreatic ducts. In endocrine pancreas, MAO-A was observed in around 50% of islet cells, whereas MAO-B was less abundant and was restricted to the periphery of islets. Thyroid gland showed strong MAO-A immunoreactivity in all cell types and was MAO-B-negative. In adrenal gland, the capsule displayed MAO-A but not MAO-B immunoreactivity, whereas the cortex showed widespread MAO-A staining but was MAO-B-negative in interstitial cells. Finally, in the medulla only a few scattered cells showed either MAO-A or MAO-B immunoreactivity. To our knowledge, these data represent the first study of the cellular distribution of MAO-A and MAO-B in the three human tissues included.

Adrenal Glands↗

PubMed2000

Age-related changes of MAO-A and -B distribution in human and mouse brain.

Age-related changes of MAO-A and -B were studied in human and BL/C57 mouse brain areas (substantia nigra, putamen and cerebellum). [3H]Ro41-1049 and [3H]lazabemide were used as selective radioligands to image and quantify MAO-A and MAO-B respectively by enzyme autoradiography. MAO-A binding was higher in mouse, whereas MAO-B binding was higher in human. With aging, mouse MAO-A was significantly reduced between 4 and 8 weeks and remained unchanged until 19 months followed by a slight increase between 19 and 25 months. In contrast, no clear variation was observed in humans between the age of 17-93 years. In most of the structures studied a clear age-related increase in MAO-B was observed beginning in mouse brain at 4 weeks, whereas in human tissue this increase started at the age of 50-60 years. These results show marked differences in the levels and variations of mouse and human MAO-A and -B associated with aging and should be taken into account when extrapolating experimental data from mouse to human.

Adolescent↗

PubMed2000

MAO-A and MAO-B localisation in human lung and spleen.

Localisation of MAO-A and -B in human lung and spleen was studied by immunohistochemistry. The primary antibodies used were mouse monoclonal anti-human MAO-A (6G11/E1) and anti-human MAO-B (3F12/G10/2E3). Samples of lung and spleen were obtained from 6 routine autopsy cases. Both immunoreactivities showed a homogeneous distribution in lung, where all cell types had both MAO-A and -B staining. In spleen MAO-A and -B showed a very weak immunoreactivity, which was restricted to smooth muscle cells and reticular cells of the white pulp. These data represent the most comprehensive study of MAO-A and -B localisation in the two tissues.

Aged↗

PubMed1999

Apolipoprotein E is essential for amyloid deposition in the APP(V717F) transgenic mouse model of Alzheimer's disease.

We quantified the amount of amyloid beta-peptide (Abeta) immunoreactivity as well as amyloid deposits in a large cohort of transgenic mice overexpressing the V717F human amyloid precursor protein (APP(V717F+/-) TG mice) with no, one, or two mouse apolipoprotein E (Apoe) alleles at various ages. Remarkably, no amyloid deposits were found in any brain region of APP(V717F+/-) Apoe(-/-) TG mice as old as 22 mo of age, whereas age-matched APP(V717F +/-) Apoe(+/-) and Apoe(+/+) TG mice display abundant amyloid deposition. The amount of Abeta immunoreactivity in the hippocampus was also markedly reduced in an Apoe gene dose-dependent manner (Apoe(+/+) > Apoe(+/-) >> Apoe(-/-)), and no Abeta immunoreactivity was detected in the cerebral cortex of APP(V717F+/-) Apoe(-/-) TG mice at any of the time points examined. The absence of apolipoprotein E protein (apoE) dramatically reduced the amount of both Abeta(1-40) and Abeta(1-42) immunoreactive deposits as well as the resulting astrogliosis and microgliosis normally observed in APP(V717F) TG mice. ApoE immunoreactivity was detected in a subset of Abeta immunoreactive deposits and in virtually all thioflavine-S-fluorescent amyloid deposits. Because the absence of apoE alters neither the transcription or translation of the APP(V717F) transgene nor its processing to Abeta peptide(s), we postulate that apoE promotes both the deposition and fibrillization of Abeta, ultimately affecting clearance of protease-resistant Abeta/apoE aggregates. ApoE appears to play an essential role in amyloid deposition in brain, one of the neuropathological hallmarks of Alzheimer's disease.

Alzheimer Disease↗

PubMed1999

Neuroprotective effects of Gly-Pro-Glu, the N-terminal tripeptide of IGF-1, in the hippocampus in vitro.

Insulin-like growth factor 1 (IGF-1) plays a critical role in CNS development. IGF-1 can block neuronal apoptosis in vitro and in vivo. IGF-1 is thought to be cleaved into des-N-(1-3)-IGF-1 and an amino terminal glycine-proline-glutamate (GPE tripeptide). Here we report a neuroprotective role for GPE tripeptide, with enhanced survival of the CA1-2 hippocampal neurons following an excitotoxic insult in vitro. Binding and displacement studies suggest uniquely distributed sites of action within the rat including the hippocampal CA1-2, pyriform cortex, amygdala, choroid plexus, blood vessels and to a lesser extent in the cortical regions. A similar pattern of binding was seen in the human. This finding could lead to new strategies to reduce neuronal death after injury and in disease.

Animals↗

PubMed1999

Long-term effects of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate and 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2,3-dione in the rat basal ganglia: calcification, changes in glutamate receptors and glial reactions.

Previous data from our laboratory indicate that 25 mM ibotenic acid induces intracellular calcifications in the rat basal forebrain. Because of the lack of specificity of ibotenic acid for a glutamate receptor subtype, a dose-response study with alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate was undertaken and calcified areas (identified with Alizarin Red staining) as well as astro- and microglial reactions (by autoradiography with [3H]lazabemide and [3H]Ro 5-4864) were quantified at one month post-lesion. alpha-Amino-3-hydroxy-5-methyl-4-isoxazole propionate administered into the globus pallidus induced, in a dose-dependent manner, the formation of calcium deposits and the activation of both glial cells, the microglial reaction being particularly robust. From this study, a dose of 5.4 mM alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate was selected for further experiments. [3H]alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate, [3H]dizocilpine maleate and [3H]PN 200-110 binding in vitro were performed to assess autoradiographically whether the tissue damage was associated with changes in glutamate receptors and calcium channel binding sites. In the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate-treated animals, the specific binding of [3H]alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate was significantly reduced by 28% in the lesioned ventral pallidum, whereas it was unchanged in the globus pallidus and substantia innominata. In these three nuclei, calcifications developed and an increase in both glial markers was measured. In contrast, the binding of [3H]PN 200-110 and [3H]dizocilpine maleate were unaffected. Co-injection of 15 mM 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2,3-dione, a selective alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate/kainate receptor antagonist, prevented the formation of calcium concretions, the microglial reaction and the decrease in [3H]alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate binding but it failed to inhibit totally the astroglial reaction induced by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate. This may suggest that the microglial reaction and calcification take place through different mechanisms from the astrogliosis associated with the neuronal loss. In conclusion, acute administration of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate in the rat globus pallidus elicits a dose-dependent calcification process associated with a chronic reaction of astrocytes and microglia. alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate-induced injury is accompanied by a slight reduction of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors in the ventral pallidum, whereas the binding of N-methyl-D-aspartate and L-type calcium channels receptors remains unchanged in any lesioned nucleus.

Animals↗

PubMed1998

CCAAT-enhancer binding protein alpha is expressed in activated microglial cells after brain injury.

Microglial cells play important roles in brain injury and repair and are implicated in diseases such as Alzheimer's disease, Creutzfeldt-Jacob disease, multiple sclerosis, the Aids Dementia Complex and stroke. Despite their importance in neuropathology, the underlying molecular basis for the activation of microglia after brain injury is not understood. We show, using RT-PCR, in situ hybridisation, immunocytochemistry, and electrophoretic mobility shift assay, that the CCAAT-enhancer binding protein alpha (C/EBP alpha), a sequence specific DNA-binding protein, is induced in microglial cells, but not astrocytes or neurons, after hypoxic-ischemic brain injury. These results suggest that C/EBP alpha might regulate gene expression and consequentially have a role in the activation and/or proliferation of microglia following brain injury.

Animals↗

PubMed1998

Monoamine oxidases: from brain maps to physiology and transgenics to pathophysiology.

The present report reviews recent advances in mapping the cellular sites of synthesis and catalytic activity, as well as age- and disease-related changes of monoamine oxidases A and B in the brain. A transgenic model of oxidative stress is also described. The relevance of these findings for the physiological and pathophysiological roles of monoamine oxidases is briefly discussed.

Alzheimer Disease↗

PubMed1997

Etoposide-induced PC12 cell death: apoptotic morphology without oligonucleosomal DNA fragmentation or dependency upon de novo protein synthesis.

Etoposide, a topoisomerase II inhibitor used in cancer therapy, has been shown to induce apoptosis in vitro in a variety of cell types. In the present study, we have characterized the effects of etoposide on undifferentiated rat pheochromocytoma PC12 cells. Etoposide killed PC12 cells in a time- and concentration-dependent manner. 20-24 h incubation with 10 micrograms/ml etoposide induced 25-50% cell death. Hoechst 33258 staining revealed apoptotic morphology in dying cells. No evidence was found of either oligonucleosomal DNA fragmentation, as shown by agarose gel electrophoresis, or endonuclease involvement, as shown by the inability of aurintricarboxylic acid to prevent cell death. Cycloheximide and actinomycin-D were unable to prevent etoposide cytotoxicity indicating that the process is not dependent upon de novo protein or mRNA synthesis. NGF (5 ng/ml) prevented etoposide-induced PC12 cell death. These results offer an example of how the morphological features of apoptosis are not necessarily associated with oligonucleosomal DNA fragmentation or with de novo macromolecule synthesis.

Analysis of Variance↗

PubMed1996

Localization of monoamine oxidases in human peripheral tissues.

Localization of monoamine oxidases (MAO) A and B and beta-adrenoceptors, was studied in aged human peripheral tissues (age 68-80 years) by quantitative autoradiography. The tissues analyzed were heart, lung, liver, kidney, spleen and duodenum. [3H]Ro41-1049 and [3H]lazabemide, two recently characterized selective radioligands were used to map MAO-A and MAO-B respectively. The regional pattern of distribution of MAO-A and MAO-B did not differ markedly, except in kidney and especially in duodenum. Highest levels of MAOs were measured in liver, and lowest in spleen. MAO-A was more abundant than MAO-B in lung and duodenal mucosa, and the reverse was true in myocardium. These results show marked differences in the abundance and patterns of distribution of MAOs, particularly MAO-B, in human and rodent peripheral tissues.

Aged↗

PubMed1996

Molecular neuroanatomy of human monoamine oxidases A and B revealed by quantitative enzyme radioautography and in situ hybridization histochemistry.

Monoamine oxidases are key enzymes in the metabolism of amine neurotransmitters and neuromodulators and are targets for drug therapy in depression, Parkinson's and Alzheimer's diseases. Knowledge of their distribution in the brain is essential to understand their physiological role. To study the regional distribution and abundance of monoamine oxidases A and B in human brain, pituitary and superior cervical ganglion, we used quantitative enzyme radioautography with radioligands [3H]Ro41-1049 and [3H]lazabemide, respectively. Furthermore, 35S-labelled oligonucleotides complementary to isoenzyme messengerRNAs were used to map the cellular location of the respective transcripts in adjacent sections by in situ hybridization histochemistry. A markedly different pattern of distribution of the isoenzymes was observed. Highest levels of monoamine oxidase A were measured in the superior cervical ganglion, locus coeruleus, interpeduncular nucleus and ventromedial hypothalamic nucleus. The corresponding messengerRNA was detected only in the noradrenergic neurons of the superior cervical ganglion and locus coeruleus. In contrast to rat brain, monoamine oxidase B was much more abundant in most human brain regions investigated. Highest levels were measured in the ependyma of ventricles, stria terminalis and in individual hypothalamic neurons. Monoamine oxidase B transcripts were detected in serotoninergic raphe neurons, histaminergic hypothalamic neurons and in dentate gyrus granule cells of the hippocampal formation. We conclude that [3H]Ro41-1049 and [3H]azabemide are extremely useful radioligands for high-resolution analyses of the abundance and distribution of catalytic sites of monoamine oxidases A and B, respectively, in human brain sections. From levels of messenger RNA detected, the cellular sites of synthesis of the isoenzymes are the noradrenergic neurons of the locus coeruleus (for monoamine oxidase A) and the serotoninergic and histaminergic neurons of the raphe and posterior hypothalamus, respectively (for monoamine oxidase B). The combination of quantitative enzyme radioautography with in situ hybridization histochemistry is a useful approach to study, with high resolution, both the physiology and pathophysiology of monoamine oxidases in human brain.

Aged↗

PubMed1995

Calcium deposit formation and glial reaction in rat brain after ibotenic acid-induced basal forebrain lesion.

The mechanisms underlying amino acid neurotoxicity may involve a rise in the intracellular concentration of calcium. Some neurons appear to die as a consequence of increased intracellular calcium levels induced by excitatory amino acids. One month after injection of ibotenic acid in the rat basal forebrain, the induced formation of calcium deposits and concomitant glial reaction were studied. Alizarine Red-positive calcium deposits were observed after ibotenic acid injection in the ventral part of the globus pallidus, but not in the medial septum. These deposits were present in the globus pallidus, ventral pallidum, substantia innominata, zona incerta, lateral hypothalamic area, entopeduncular nucleus, medial amygdaloid nucleus and several thalamic nuclei. Three types of round shaped deposit were identified morphologically. Differential astroglial and microglial reactions, studied autoradiographically with the monoamine oxidase-B marker [3H]Ro19-6327 and the peripheral benzodiazepine receptor marker [3H]Ro5-4864 respectively, were observed after both lesions. Our data suggest that excitotoxic lesions in the globus pallidus and medial septum lead with time to different neurodegenerative consequences and glial reactions. This differential sensitivity is discussed on the basis of the presence of different glutamate receptor subtypes and calcium-binding proteins.

Animals↗