Biomedical subjects

A Assal

Publications and source records attributed to A Assal.

4 recordsLinked to original sources

PubMed2003

[Application of molecular biology to blood transfusion safety: the nucleic acid testing].

Nucleic Acid Testing (NAT) for HIV-1 and HCV has been introduced in France and became mandatory for all homologous blood donations since July 1st 2001 in addition to serology screening. Previously, a feasibility study led to the selection of 2 technologies : a TMA based assay (Chiron) uses the Procleix HIV-/HCV assay on pools of 8 samples and a PCR based assay from BioMérieux-Roche which is a combination of an RNA extraction system (NucliSens, BioMérieux) with a fully automated system for nucleic acid amplification and detection (Cobas Amplicor, Roche). This system uses the Cobas Ampliscreen HCV test v.2.0 and the The Cobas Ampliscreen HIV test v1.5, on 24 sample pools. Pooling was required because single-donation testing is not yet feasible, as a result of the limitations in automation available for all current NAT technologies. The two technologies were easily implemented and showed nearly the same detection limit for HCV RNA and HIV-1 RNA. During a one-year period, from July 1st 2001 to June 30, 2002, out of the 2.5 million donations tested, the NAT yield resulted in one HIV-1 RNA positive-antibody negative donation and one HCV RNA positive-antibody negative donation. Two HIV NAT positive-antibody negative donations were missed by minipool NAT because a very low viral load. Moreover, the NAT implementation did not impact on blood component availability, including platelet concentrates.

Blood Transfusion↗

PubMed1999

[Comparison of two techniques for detection of anti-Plasmodium falciparum antibodies: Falciparum-spot IF (Biomérieux) and Malaria IgG Celisa (BMD). Preliminary results].

We compared a new Elisa assay to detect malaria antibodies: Malaria IgG Celisa (BMD) with the IFAT technique Falciparum-spot IF (Biomérieux): sensitivity, specificity, predictive positive and negative values were 81%, 99%, 95%, 95%, respectively. Eight patients had positive thick blood smear out of 23 performed. For these eight confirmed acute malaria cases, the Elisa assay was negative in five instances. For two recent malaria attacks both Elisa and IFI were negative. With blood donors, two sera were IFAT positive and Elisa negative; 16 were IFAT doubtful and Elisa negative. Doubtful results rose up to 13.5% by IFAT against 1.5% by Elisa assay. We preferred kappa coefficient instead of chi 2 test for data analysis, which measures the concordance degree between the two techniques. Here concordance is moderate. Choosing an Elisa assay to detect the transmission of malaria for at-risk blood donors collides with the method sensitivity compared with IFAT as reference.

Animals↗

PubMed1995

[Trophoblastic interferons and embryonal immune tolerance].

Current evidence support the hypothesis that trophoblast interferons play a key role in preventing maternal immunologal rejection of the embryonic semi-allograft. The information of this review is divided in two sections. In the first section we described molecular and biological characteristics of type I (alpha, beta, omega, tau and spl) and type II (gamma) interferons. In the second section we emphasize studies on immunoendocrine functions of IFN-tau (oTP-1 or trophoblastins) in the network of cytokines and hormonal environment at the uterine embryonic interface.

Animals↗

PubMed1993

Characterization of the bisphosphonate recognition site on hydroxyapatite using radioligand binding techniques with [14C]citric acid.

The present studies characterize the binding of [14C]citric acid to synthetic hydroxyapatite (HA) crystals. [14C]Citric acid specifically bound to HA and was dependent upon the concentration of HA in the assay. The binding of [14C] citric acid to HA reached equilibrium within 20 min and remained stable for at least 90 min. Dissociation of bound [14C]citric acid was biphasic in nature since both rapid and more slowly reversible binding components were detected. Saturation experiments also indicated that [14C]citric acid labeled two recognition sites with different affinity (KdH = 42 nM and KdL = 24,000 nM) and density (BmaxH = 161 fmol/micrograms HA and BmaxL = 8.8 pmol/micrograms HA). Ligand competition experiments revealed that compounds that are known to readily bind bone (e.g., sodium pyrophosphate, methylene diphosphonic acid, etidronate) potently inhibited the binding of [14C]citric acid to HA, whereas compounds known to have poorer affinity for bone (e.g., oxalic acid and GABA) did not. Computer analysis of these inhibition curves revealed specific ligand interactions at two different affinity recognition sites. The present results indicate that [14C]citric acid binds discrete sites on synthetic HA in a fashion consistent with a specific labeling of the bisphosphonate recognition site. Analysis of the binding of [14C]citric acid to HA provides a useful method to further explore the structure activity relationships of novel compounds that have binding affinity for bone.

Binding Sites↗