Search PubMed⌕ Search

Biomedical subjects

F Simon

Publications and source records attributed to F Simon.

At least 55 records · Page 3Linked to original sources
PubMed1998

HIV type 1 diversity and the reliability of the heteroduplex mobility assay.

We investigated HIV-1 diversity by means of heteroduplex mobility assay (HMA) genotyping. We studied 199 samples from patients originating from 26 countries and living in France. The HMA successfully genotyped 182 (91%) of these samples, as follows: 77 (42%) subtype A, 57 (31%) subtype B, 5 (3%) subtype C, 5 (3%) subtype D, 8 (4%) subtype E, 22 (12%) subtype F, 5 (3%) subtype G, and 3 (2%) subtype H. We were not able to genotype 12 samples by means of the HMA. These latter strains were sequenced, and phylogenetic analyses revealed that they were highly divergent subtype A-, D-, or G-related strains. Eight (of 12) subtype D strains were indeterminate by HMA, owing to the broad intrasubtype diversity, suggesting that new reference subtype D plasmids are required, as previously proposed. Thirty-seven strains belonging to the different subtypes were sequenced, and the results showed perfect concordance with the HMA results. Interlaboratory quality controls confirmed the reliability of the HMA for HIV-1 subtyping, despite the extensive viral variability. However, plasmid selection must be continuously revised to cover viral diversification.

Amino Acid Sequence↗
PubMed1998

HIV-1 diversity in Romania.

OBJECTIVES: To evaluate the prevalence and the dynamics of HIV-1 subtypes in Romanian adults and children, and to investigate the origins of the nosocomial epidemic. DESIGN: A total of 1000 serum and plasma samples, from adults (n = 579) and children (n = 421) who were diagnosed as being HIV-1-infected during 1990-1997 in 39 of the 41 Romanian districts, were serotyped. Viral DNA was isolated from blood samples of 84 patients and the viruses were genotyped. METHODS: Serotyping was performed with a peptide subtype-specific enzyme immunoassay (SSEIA), based on in vitro competition for antibody binding between the representative V3 peptides of the different clades (A-F). Proviral HIV-1 DNA was genotyped by heteroduplex mobility assay or by sequence analysis of the C2-V3 env region. RESULTS: SSEIA showed that 93% of the samples from horizontally infected children were serotype F, 1% were serotype B, and the remaining 6% were uninterpretable. In vertically infected children, 74% of strains were serotype F, 10% were serotype A, 3% were serotype B, and 3% were serotype E. Serotype F was also the dominant subtype in adults (68%), but serotypes A, B, C, D and E were also detected. SSEIA gave indeterminate results in 7% of cases. A strong correlation (90%) between serotyping and genotyping for subtype F was found. Analysis of the relative incidence of the different serotypes over a 7-year period (1990-1997) showed a stable distribution. CONCLUSIONS: Subtype F largely dominates the epidemiology of HIV-1 infection in both children and adults in Romania, although other major subtypes are present. The predominance of subtype F in Romania may be a future potential source of HIV-1 variability in Europe.

Adult↗
PubMed1998

Identification of a new human immunodeficiency virus type 1 distinct from group M and group O.

A highly divergent HIV-1 isolate, designated YBF 30, was obtained in 1995 from a 40-year-old Cameroonian woman with AIDS. Depending on the genes studied, phylogenetic analysis showed that YBF30 branched either with SIVcpz-gab or between SIVcpz-gab and HIV-1 group M. The structural genes and tat, vpr, and nef of YBF30 are approximately equidistant from those of HIV-1 group M and SIVcpz-gab. In contrast, vif and rev are closer to HIV-1 group M, and vpu is highly divergent. Using a YBF30 V3 loop peptide enzyme immunoassay, we screened 700 HIV-1-positive sera collected in Cameroon; three reacted strongly with the YBF30 peptides and one was confirmed as being related to YBF30 by genetic analysis of a pol fragment. YBF30 is as distinct from SIVcpz-gab as it is from HIV-1 group M and can thus be considered as the prototype strain of a new human immunodeficiency virus group.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Alginate gel culture allows the retention of extracellular matrix and follicular structure of rat thyroid tissue but does not lead to the formation of follicles by FRTL-5 cells.

Extracellular matrix (ECM) and basement membrane (BM) components were studied by immunohistological methods in native rat thyroid tissue, and in rat thyroid tissue and FRTL-5 cells cultured in a three-dimensional alginate bead system. In all three situations, the presence of collagen IV, laminin, perlecan, and fibronectin was demonstrated. There were marked differences between rat thyroid tissue and FRTL-5 cells in culture. Rat thyroid tissue maintained a follicular structure, whereas FRTL-5 cells did not form follicles. Rat thyroid cells multiplied more slowly than FRTL-5 cells and thyroglobulin (Tg) was visible in the follicular lumen, while in FRTL-5 cells Tg was only seen intracellularly. Tg iodination was much lower in FRTL-5 cells than in rat cells. In rat thyroid cells, positive staining for collagen IV, laminin, and perlecan was seen in thin membranes around individual follicles, and for fibronectin around groups of follicles. In FRTL-5 cells, these ECM/BM components could be identified, but were not organized into equally regular networks around groups of cells. These results demonstrate that of the two types of cells examined, primary cultures of rat thyroid cells in alginate beads maintain structural and functional similarities to native thyroid tissue and would therefore be suitable for future in vitro studies of thyroidal ECM/BM and their interrelationship with growth and function of this organ. FRTL-5 cells cultured in alginate beads show some functional, but not structural similarities to native thyroid tissue and so would be less valuable for use in such studies.

Alginates↗
PubMed1998

Highly sensitive method for amplification of human immunodeficiency virus type 2 DNA.

We evaluated a new human immunodeficiency virus type 2 (HIV-2) DNA amplification strategy based on peripheral blood mononuclear cell long PCR (XL PCR) followed by nested PCR amplification. The primers used were located in the highly conserved long terminal repeat and in the pol regions of the genome. Five primer pairs corresponding to different regions of the HIV-2 env gene were used in the nested step. Samples from 42 patients were tested, which yielded positive amplification with at least two primer pairs in 40 (95%) samples. A primer pair (EB2/EB5) located on the V3 region succeeded in amplifying proviral DNA in 40 samples.

DNA Primers↗
PubMed1998

Human immunodeficiency virus type 1 subtype F reverse transcriptase sequence and drug susceptibility.

We sequenced and phylogenetically analyzed the reverse transcriptase (RT) regions of the pol genes of 14 human immunodeficiency virus type 1 (HIV-1) isolates from Romanian patients, which were classified as subtype F on the basis of env gene structure. The RT sequences showed that the strains clustered phylogenetically and were equidistant from other HIV-1 subtypes as shown by the neighbor-joining and maximum-likelihood methods, allowing us to define HIV-1 subtype F according to the pol classification. The subtype F RT sequences differed from reported group M RT sequences by 10.94% (for nucleotides) and 7.6% (for amino acids). Phenotypic analysis of subtype F susceptibility to three classes of antiretroviral compounds showed an increase in the 50% inhibitory concentration of the tetrahydroimidazo[4,5,1-jk] [1,4]-benzodiazepin-2-(1H)-one and -thione (TIBO) derivate R82913 for one strain which was naturally resistant to this compound. This first report of subtype F pol sequences confirms the perfect correlation between the phylogenetic positions determined by env and pol analyses and suggests that virus variability might influence the efficacy of antiretroviral treatments. This finding warrants a global evaluation of the phenotypic and genotypic susceptibility of HIV-1 subtypes to antiretroviral drugs.

Adult↗
PubMed1998

[Rifampicin].

Explore the source record for details and available documents.

Antibiotics, Antitubercular↗
PubMed1998

[The Dakin solution].

Explore the source record for details and available documents.

Anti-Infective Agents, Local↗
PubMed1998

[Quinine].

Explore the source record for details and available documents.

Antimalarials↗
PubMed1998

[Difficult catheterization].

We report a case of a spontaneously ruptured implantable-chamber catheter which migrated to the right atrium. Removal by interventional radiology techniques is the treatment of choice for this type of complication.

Aged↗
PubMed1997

Synthetic peptide ELISAs for detection of and discrimination between group M and group O HIV type 1 infection.

We developed and evaluated two peptide-based immunoassays to confirm and discriminate between group M and group O HIV-1 infection. These assays are based on in vitro competition for antibody binding between M and O peptides. The first EIA is based on competition between group M and group O gp41 immunodominant domains and the second on competition between group O and group M V3 regions of gp120. Two panels of sera were used: the first consisted of 109 sera collected from 27 group O- and 92 group M-infected patients in whom the HIV isolates had been genotyped by sequencing or heteroduplex mobility assay. In this panel, the combination of the two assays correctly discriminated 106 samples (100% group O and 96.7% group M samples). The second panel, used for the field evaluation of the two assays, consisted of 157 samples from HIV-1-infected Cameroonian patients, 33 strains having been genotyped. The combination of the two techniques in a serogrouping algorithm discriminated 147 of these samples, 74 being HIV-1 group O and 73 group M. These results always correlated with genotyping results. The 10 sera that were not successfully classified by these assays were from early seroconverters. Altogether, the two assays clearly differentiated 263 of 276 (94.9%) samples in the two panels. On the basis of the genotyping results, the positive predictive value for group discrimination in the two panels was 100% for both GSEIA assays. Our peptide-blocking group-specific EIAs for differentiation and confirmation of HIV-1 group M and group O infection are complementary tools for epidemiological studies and surveillance of HIV-1 group O strain trafficking.

Amino Acid Sequence↗
PubMed1997

Feline heartworm (Dirofilaria immitis) infection: detection of specific IgG for the diagnosis of occult infections.

Sera from 54 cats, 53 asymptomatic and one symptomatic (chronic dyspnoea and coughing), living in a hyper-endemic area for canine heartworm (Dirofilaria immitis) infection were studied to evaluate the reliability of two ELISA-based antibody tests coupled with both somatic (ELISASA) and excretory/secretory (ELISAE/S) antigens. All cats were examined by echocardiography and radiography. In addition, an ELISA-based test to detect adult female heartworm circulating antigens and a modified Knott test for microfilariae in the blood were carried out on all cats. No cat was positive for microfilariae in the blood. Heartworms were visualized in 12 of 54 cats by echocardiography. Of these, three asymptomatic cats and the symptomatic one had radiographic signs of infection and were the only ones positive for heartworm circulating antigens. All sera except two were positive when analyzed in ELISA(SA). In ELISA(E/S), nine sera were positive but three were negative. No sera from the 42 echocardiography-negative cats was positive in ELISA(E/S), but 11 were positive in ELISA(SA). Western blot analyses with somatic antigens of sera from echocardiography-positive cats showed at least four bands of recognition between 19 and 30 kDa and one of about 40 kDa. With E/S antigen, a large band of about 22 kDa and one of about 25 kDa were recognized; these appear to be most specific.

Animals↗