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Biomedical subjects

S Hamdi

Publications and source records attributed to S Hamdi.

10 recordsLinked to original sources
PubMed2005

[Intra-individual variability of the platelet anti-aggregation effect of aspirin in coronary patients].

UNLABELLED: Several studies have reported a biochemical resistance to aspirin in 5 to 10% of coronary patients. However, the stability of the platelet anti-aggregation effect with aspirin over time remains poorly understood. OBJECTIVE: To study the intra-individual variability at 6 months of the anti-platelet action of aspirin in coronary patients. METHOD: Prospective study including 40 consecutive patients with acute coronary syndrome and taking regular aspirin (250 mg a day). The biochemical impact of aspirin was determined by measuring the time to occlusion (TO) on a collagen/epinephrine cartridge with PFA-100. The determination of the TO was performed 2 months (TO1) and then 8 months (TO2) after starting aspirin. In our population, a resistance to aspirin was defined as a TO < or =125 sec. RESULTS: The median value for TO was generally stable over the two periods, at 158 sec for TO1 and 179 sec for TO2 (p = 0.29). Among the 9 initially resistant patients (22.5%), 4 became sensitive to aspirin without changing the dosage, while only one of the 31 initially sensitive patients became biochemically resistant. CONCLUSION: the existence of a medium term intra-individual variability in the antiplatelet response to aspirin in coronary patients underlines the importance of biochemical surveillance in these high vascular risk patients.

Acute Disease↗
PubMed2002

Influence of poly(methyl methacrylate) impregnation ratio on the surface properties of fumed silica and on the glassy temperature of poly(methyl methacrylate) using inverse gas chromatographic analysis.

The surface properties of poly(methyl methacrylate) (PMMA) impregnated fumed silicas, in a large range of impregnation ratios, were examined using inverse gas chromatography at infinite dilution. It was observed that the dispersive component gamma(s)d does not decrease monotonously with the impregnation ratio. Two critical coverage ratios were evidenced corresponding at first to the shielding of the most energetic sites and then to the achievement of total coverage of the silica surface. The influence of the coverage ratio on the glassy temperature (tg) of the adsorbed PMMA was also studied, which was evidenced down to a very low coverage ratio (1 monomer unit/nm2).

Adsorption↗
PubMed2000

[In situ PCR].

Explore the source record for details and available documents.

Chromosome Aberrations↗
PubMed1999

Development of a direct in situ RT-PCR method using labeled primers to detect cytokine mRNA inside cells.

We have developed an original protocol of direct in situ RT-PCR with biotinylated labeled primers to detect cytokine mRNA inside cells. This label improved the specificity of the technique compared with the use of digoxigenin or fluorescein-labeled primers. We found a reliable correlation between the known expression of cytokine mRNA in a given cell and a positive signal with in situ RT-PCR. Nuclear counterstaining demonstrated that the positive signal obtained was distributed in the cytoplasm in accordance with mRNA localization. In addition, direct demonstration of the presence of the expected PCR product in cell extracts without non-specific parasitic DNA amplification provided strong support for the specificity of the method. Designing the primers in order to prevent DNA amplification, the use of recombinant Thermus thermophilus (rTth) DNA polymerase and a decreased duration of each cycle of PCR by combining the annealing and hybridization steps improved the reproducibility and reliability of the technique and morphological preservation of the cells. Experiments in which different proportions of cytokine mRNA positive and negative cells were mixed argue against significant diffusion of PCR product into initially cytokine mRNA negative cells, thereby leading to false-positive results. In comparison with the direct incorporation of labeled dNTP during amplification, our procedure appears to ensure greater specificity and does not need DNAse treatment which is often difficult to standardize. Detection of IL-2 and IFNgamma mRNA induction after T cell activation using this direct in situ RT-PCR method showed that the technique may be helpful for monitoring cytokine gene expression at a single cell level.

Animals↗
PubMed1998

Molecular characterization of a cytokinin-inducible periwinkle protein showing sequence homology with pathogenesis-related proteins and the Bet v 1 allergen family.

Cytokinin treatment of periwinkle callus cultures increased the accumulation of a protein, designated T1, in two-dimensional separated protein extracts. The first 30 NH2-terminal amino acids were determined by Edman degradation and showed significant sequence homology with intracellular pathogenesis-related (IPR) plant proteins and the Bet v 1 allergen family. The deduced amino acid sequence of cDNAs coding for T1, isolated by RT-PCR and 5' RACE-PCR, exhibited an average sequence identity of 40% with both IPR and Bet v 1-related allergens. T1 and all related proteins contained a p-loop motif typically found in nucleotide-binding proteins as the most conserved sequence feature. Northern blot analysis showed that cytokinin treatment of periwinkle callus induced T1 transcripts, whereas addition of 2,4-dichlorophenoxyacetic acid inhibited this accumulation. Hybridization of genomic periwinkle DNA with the T1 cDNA suggested that the protein is encoded by a single-copy gene. Immunoblot studies with a panel of Bet v 1-specific antibodies and sera from Bet v 1 allergic individuals identified T1 as a protein that is immunologically distinct from the Bet v 1 allergen family and has no allergenic properties.

Allergens↗
PubMed1997

[Characterization of a protein related to Bet v 1, the major birch pollen antigen, from cells of the Madagascar periwinkle. Universal presence of proteins of this type among higher plants].

In this work we present the characterisation of a gene that codes for a protein of 17 kDa, in in vitro cultures of a plant with ornamental and pharmaceutical properties, the Madagascan periwinkle, (Catharanthus roseus [L] G. DON). This protein is very close to the principal allergen of birch and also to allergens isolated from or demonstrated in some foods such as celery, parsley, apple tree, peas, asparagus and potato, but it has no allergenic characteristics.

Allergens↗
PubMed1987

Master Regulatory Genes, Auxin Levels, and Sexual Organogeneses in the Dioecious Plant Mercurialis annua.

In Mercurialis annua L. (2n = 16) genes for sex determination are considered as major regulator genes controlling stamen and ovary development and sexual phenotypes. After stamen induction, sterility determinants control sporogenous tissue and pollen formation. Moreover, exogenous auxins are able to induce male flowers on female plants. In order to verify if sex and sterility genes have an effect on indole-3-acetic acid (IAA) contents of these plants, various wild or genetically constructed strains were assayed. The IAA levels of their apices were determined by HPLC followed by gas chromatography, selected ion monitoring, mass spectrometry. Results show that high auxin levels are linked to male phenotypes. The genes inducing maleness and the determinants of restored male fertility appear to control and modulate the IAA content. Close correspondence between the number of these dominant genes and IAA levels was established. A final hypothesis about the control of sexual specialization by phytohormones induced by the presence of these genes is discussed.

Journal Article↗
PubMed1977

[Prolonged ovarian pregnancy associated with an intrauterine pregnancy. Apropos of a case].

Case of advanced ovarian pregnancy are exceptional because ovarian pregnancy itself is very rare. The authors describe a case of prolonged ovarian pregnancy with retention of the dead fetus for more than a year and associated with an intra-uterine pregnancy. Usually ovarian pregnancy finishes in rupture which occurs before the end of the first trimester. It is then difficult to make out the intergrity of the organs and in particular of the tube and indeed to recognize them. On the other hand when the mass persists intact with the development of the pregnancy in a retort shape, it is easy to see how confusion is possible and arises between it and an intra-uterine pregnancy. In this case, however, the different anatomical forms are clear and an almost definite diagnosis can be made at the time of operation (the three first criteria of Spiegelbery). The diagnosis of ovarian pregnancy is never made before operation. At the very best one can say, when things happen early, that an extra-uterine pregnancy has ruptured, or in certain particular circumstances like in the case we are reporting lithopedian. The presence of ovarian tissue in the wall of the sac--which is the fourth criterion of Spiegelberg-is easier to recognize in early accidents than in advanced cases of ovarian pregnancy in which the parenchyma of the ovary is compressed, distended and laminated by the increasing development of the fetus and the adnexae. The absence of the placenta being adherent to other organs than the ovary can then be kept as a worthwhile criterion of ovarian pregnancy.

Adult↗
PubMedDate not supplied

Characterization of exosome subpopulations from RBL-2H3 cells using fluorescent lipids.

Fluorescent lipid probes were used to track lipid trafficking between parent RBL cells and exosomes. We have checked the intracellular labeling of exosomes ("in vivo labeling") from parent cell incubated with either Bodipy-Cer, Bodipy-PC, or NBD-PC. Bodipy-PC labeled equally cells and exosomes, whereas Bodipy-Cer, a Golgi marker, was enriched in exosomes. Golgi membranes participated effectively in exosome biogenesis since cell incubation with brefeldin A leads to a modified phospholipid/protein ratio in exosomes. At the opposite, NBD-PC, a plasma membrane marker weakly labeled exosome membranes. Sorting of subpopulations indicated that the MHC-II containing exosomes were enriched in Bodipy-PC, whereas tetraspanin(CD 63 or CD81)-containing exosomes are essentially labeled with Bodipy-Cer and Bodipy-PC. These results indicated that RBL released two main subpopulations of exosomes that can be discriminated by their protein and lipid contents. When the bulk of exosomes was labeled after their purification ("in vitro labeling") with either of the above-mentioned lipid probes, the Bodipy-Cer was the only one to incorporate noticeably in all the subpopulations, indicating that the previous results obtained during "in vivo labeling" monitored real intracellular lipid trafficking between organelles and exosomes. Bodipy-Cer was further used as a tool to measure the respective amounts of each subpopulations. CD63, MHC II, and CD81-containing exosomes accounted for 47%, 32%, and 21%, respectively, of total exosomes.

Animals↗