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Biomedical subjects

E Reynaud

Publications and source records attributed to E Reynaud.

14 recordsLinked to original sources
PubMed2006

Neural responses to dynamic expressions of fear in schizophrenia.

Abnormalities in social functioning are a significant feature of schizophrenia. One critical aspect of these abnormalities is the difficulty these individuals have with the recognition of facial emotions, particularly negative expressions such as fear. The present work focuses on fear perception and its relationship to the paranoid symptoms of schizophrenia, specifically, how underlying limbic system structures (i.e. the amygdala) react when probed with dynamic fearful facial expressions. Seven paranoid and eight non-paranoid subjects (all males) with a diagnosis of schizophrenia took part in functional magnetic resonance imaging study (1.5T) examining neural responses to emerging fearful expressions contrasted with dissipating fearful expressions. Subjects viewed emerging and dissipating expressions while completing a gender discrimination task. Their brain activation was compared to that of 10 healthy male subjects. Increased hippocampal activation was seen in the non-paranoid group, while abnormalities in the bilateral amygdalae were observed only in the paranoid individuals. These patterns may represent trait-related hippocampal dysfunction, coupled with state (specifically paranoia) related amygdala abnormalities. The findings are discussed in light of models of paranoia in schizophrenia.

Adolescent↗
PubMed2003

Changes in glycation of fibrous type I collagen during long-term in vitro incubation with glucose.

The course of glycation of calf skin fibrous type I collagen was monitored in vitro under physiological conditions during an 8-week incubation period in order to take into account the long half-life of this protein. The formation of glycated compounds was measured by determining fructosamine, pentosidine, and carboxymethyllysine content. The incubation conditions were as physiological as possible in sterile saline phosphate buffer, except glucose concentration. With incubation medium containing 200 mmol glucose, fibrous collagen underwent solubilization; in addition an increase in fructosamine, pentosidine, and carboxymethyllysine content in both solubilized and remaining insoluble collagen was noticed. There was a spontaneous, restricted, and time-dependent native glycated state of collagen; high concentration glucose enhanced the formation of glycated compounds and induced changes in solubility and glycoxidated products. The production of pentosidine during incubation without glucose should be considered as an event resulting from the initial fructosamine. Whereas the production of carboxymethyllysine during long-term incubation with glucose provided indirect proof of an additional oxidative process after early glycated product formation. These experimental observations provide insight into the in vivo context of advanced glycation end product formation in chronic hyperglycemia and aging.

Animals↗
PubMed2003

In vitro glycoxidation of insoluble fibrous type I collagen: solubilization and advanced glycation end products.

The deleterious effects of glycoxidation are dependent on the half-life of proteins. Collagen, the main component of extracellular matrices, is a long live protein and thus may be sensitive to the glycoxidation process. We incubated calf skin fibrous type I collagen in PBS at 37 degrees C with glucose. The fibrous type I collagen was solubilized and an increase in the amount of advanced glycation end products of the solubilized fraction was observed. As there was no bacterial contamination and no proteolytic activities in the incubation medium, the solubilization of fibrous type I collagen is probably due to the speculative production of the free radicals in our experimental conditions. To test this hypothesis, fibrous type I collagen was incubated in PBS with AAPH (2,2'azo-bis 2-aminodinopropane) a free radicals generator. AAPH induced a dramatic and dose dependent solubilization of fibrous type I collagen.

Amidines↗
PubMed2002

Serum pentosidine as an indicator of Alzheimer's disease.

Pentosidine, an advanced glycation end product (AGE), was assayed by HPLC in serum proteins from patients with Alzheimer type dementia (AD), patients with diabetes mellitus (D), and healthy (C) age-matched old subjects (mean age from each group = 84 years). Serum pentosidine was significantly different between the three groups despite similar renal function (serum creatinine < 160 micromol/L). In all groups of patients, pentosidine was independent of glycated hemoglobin (HbA1C) and the early glycation marker fructosamine and appeared to be an independent marker, mainly bound to serum albumin. Pentosidine could be an important factor useful for the diagnosis of Alzheimer's disease.

Aged↗
PubMed2001

Synergy between ascorbate and alpha-tocopherol on fibroblasts in culture.

Ascorbate and tocopherol are important antioxidants that protect cells against oxidative stress. The interaction of ascorbate and alpha-tocopherol in cells is difficult to detect as both ascorbate and alpha-tocopherol are unstable in vitro in a biological medium. We examined the interactions between human dermal fibroblasts, ascorbate and alpha-tocopherol to determine the effects of the vitamins on growth and cell viability. The interaction of ascorbate and alpha-tocopherol was studied in a fibroblast culture medium during 48h. Ascorbate and alpha-tocopherol were detected by fluorimetry after high-performance liquid chromatography (HPLC). Cell growth and cell viability were studied by cell numeration after trypan blue staining. The ascorbate concentration fell in presence of alpha-tocopherol in cell culture medium under all experimental conditions, with or without cells. Ascorbate partly protected alpha-tocopherol but only in presence of cells. Cell viability was preserved by alpha-tocopherol whereas ascorbate enhanced fibroblast growth. The synergy between ascorbate and alpha-tocopherol corresponds to a consumption of ascorbate which spares alpha-tocopherol but only in presence of cells.

Ascorbic Acid↗
PubMed1999

The Drosophila melanogaster homologue of the Xeroderma pigmentosum D gene product is located in euchromatic regions and has a dynamic response to UV light-induced lesions in polytene chromosomes.

The XPD/ERCC2/Rad3 gene is required for excision repair of UV-damaged DNA and is an important component of nucleotide excision repair. Mutations in the XPD gene generate the cancer-prone syndrome, xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy. XPD has a 5'- to 3'-helicase activity and is a component of the TFIIH transcription factor, which is essential for RNA polymerase II elongation. We present here the characterization of the Drosophila melanogaster XPD gene (DmXPD). DmXPD encodes a product that is highly related to its human homologue. The DmXPD protein is ubiquitous during development. In embryos at the syncytial blastoderm stage, DmXPD is cytoplasmic. At the onset of transcription in somatic cells and during gastrulation in germ cells, DmXPD moves to the nuclei. Distribution analysis in polytene chromosomes shows that DmXPD is highly concentrated in the interbands, especially in the highly transcribed regions known as puffs. UV-light irradiation of third-instar larvae induces an increase in the signal intensity and in the number of sites where the DmXPD protein is located in polytene chromosomes, indicating that the DmXPD protein is recruited intensively in the chromosomes as a response to DNA damage. This is the first time that the response to DNA damage by UV-light irradiation can be visualized directly on the chromosomes using one of the TFIIH components.

Amino Acid Sequence↗
PubMed1998

Molecular analysis and chromosome mapping of the H2A, H3 and H4 histone genes from the malaria vector Anopheles gambiae.

In this article we report the cloning and analysis of PCR generated fragments that encode H2A, H3 and H4 histone genes from the malaria vector An. gambiae. Sequence analysis indicated that some conservative changes are present in the An. gambiae H2A and H4 genes as compared with histone genes from other organisms. Divisional mapping showed that these genes map in division 20 on the left arm of the second chromosome. Southern blot experiments and the molecular characterization of the genomic fragment containing the H2A, H2B, H3 and H4 genes showed that they are organized in a cluster with an orientation different from the one found in other dipterans.

Amino Acid Sequence↗
PubMed1997

Antisense suppression of the putative ribosomal protein S3A gene disrupts ovarian development in Drosophila melanogaster.

The Drosophila melanogaster homologue of the Anopheles gambiae C3 cDNA has been isolated and characterized by sequence analysis. The encoded protein was localized by immunochemical and immunocytochemical methods. The Drosophila C3 protein is highly similar to homologues of disputed function, which have previously been identified in fungi, plants and animals. The protein is ubiquitous and localized in the cytoplasm. Cell fractionation followed by detection with a specific antibody preparation shows that the protein is associated with the 40S ribosomal subunit. The C3 gene is located in section 101F of chromosome 4. Antisense transgenic analysis shows that this gene is essential for oogenesis. The most prominent phenotype resulting from antisense depletion of C3 RNA is disappearance of the follicular cells of the ovary (where the concentration of C3 protein is normally high) and abnormalities of the associated germline derivatives, leading to failure of egg production.

Amino Acid Sequence↗
PubMed1997

Cloning and characterization of cDNAs preferentially expressed in the ovary of the mosquito, Anopheles gambiae.

We used differential screening to isolate from an ovarian cDNA library two expressed sequences that are enriched substantially in ovaries of blood-fed female Anopheles gambiae, as compared to female carcass and male mosquitoes. One of these clones encodes an isoform of histone H2B, whose transcript is polyadenylated at the 3' end. The other cDNA clone encodes a protein that is highly conserved in evolution and has been implicated in growth control although its function is still obscure. Both genes can be used to study gene activation during An. gambiae oogenesis.

Amino Acid Sequence↗
PubMed1993

Ionic bases of the membrane potential and intracellular pH changes induced by speract in swollen sea urchin sperm.

Signal transduction initiated by the egg peptide, speract, in sea urchin sperm is not fully understood. Hypotonically swollen sperm are a suitable model to study peptide signal transduction. Ion substitution experiments now indicate (i) that the permeability to Na+, Ca2+, and Mg2+ contributes to the sperm resting membrane potential; (ii) the repolarization induced by nM concentrations of speract is Na+ dependent and mediated by an as yet unidentified channel; (iii) the depolarization triggered by nM concentrations of speract involves Ca2+ channels since it is Ca(2+)-dependent and blocked by Co2+ and Ni2+, two Ca2+ channel blockers; (iv) hyperpolarizing swollen sperm with valinomycin increases intracellular pH (pHi) in the same way as speract, thus the speract-induced hyperpolarization may be responsible for the pHi increase.

Animals↗
PubMed1991

A new affinity adsorbent for the purification of phospholipases A1 and A2 from animal venoms.

Dimethyl-DL-2,3-distearoyloxy-propyl-2'-hydroxy-ethylammonium++ + (Rosenthal's inhibitor) was coupled to carboxyhexyl-Sepharose 4B, through carbodiimide chemistry. Phospholipase A2 from Heloderma horridum horridum and Crotalus adamanteus bind to the immobilized ligand in the presence of Ca2+ and can be easily eluted under acidic conditions or in the presence of a chelating agent, respectively. This affinity media proved to be effective also in the purification of a Ca2(+)-independent phospholipase A1 from vespid venom.

Animals↗