Biomedical subjects

C Chappey

Publications and source records attributed to C Chappey.

28 records · Page 2Linked to original sources

PubMed1993

Diversity of the V3 region of HIV in Paris, France.

OBJECTIVE: To carry out, within France, a large-scale molecular epidemiological investigation on the principal neutralizing determinant of HIV-1, located in the third variable region (V3) of the envelope protein. Such investigations are of the utmost importance in the identification and monitoring of the distribution and spread of different viral strains internationally. DESIGN: Using polymerase chain reaction (PCR), we examined the genetic variation of the V3 region sequences of 28 HIV-infected patients from Paris, France. RESULTS: Comparison of the Parisian V3 loop sequences with other published data indicates that the range of diversity in France is included within that of a large group that contains sequences from North America, the rest of Europe, Japan, India and Africa. Variability appears to be lower in the V3 loop than in its flanking regions. Five out of the six putative N-linked glycosylation sites show preferential alterations to charged amino acids. We report two motifs at the tip of the loop that have not been described previously. CONCLUSIONS: The structural homogeneity and the wide geographic representation of the major V3 group suggests that a common strategy could be applied to a large proportion of isolates in the development of a broad-spectrum HIV vaccine.

Acquired Immunodeficiency Syndrome↗

PubMed1993

B epitopes and selection pressures in feline immunodeficiency virus envelope glycoproteins.

In order to map linear B epitopes in feline immunodeficiency virus (FIV) envelope glycoproteins (Env), a random library of FIV Env polypeptides fused to beta-galactosidase and expressed in Escherichia coli was screened by using sera from experimentally FIV-infected cats. We mapped five antibody-binding domains in the surface envelope glycoprotein (SU1 to SU5) and four in the transmembrane envelope glycoprotein (TM1 to TM4). Immunological analysis with 48 serum samples from naturally or experimentally infected cats of diverse origins revealed a broad group reactivity for epitopes SU2, TM2, and TM3, whereas SU3 appeared as strictly type specific. To study selection pressures acting on the identified immunogenic domains, we analyzed structural constraints and distribution of synonymous and nonsynonymous mutations (amino acids unchanged or changed). Two linear B epitopes (SU3 and TM4) appeared to be submitted to positive selection for change, a pattern of evolution predicting their possible involvement in antiviral protection. These experiments provide a pertinent choice of oligopeptides for further analysis of the protective response against FIV envelope glycoproteins, as a model to understand the role of antibody escape in lentiviral persistence and to design feline AIDS vaccines.

Animals↗

PubMed1993

Simian immunodeficiency viruses from central and western Africa: evidence for a new species-specific lentivirus in tantalus monkeys.

Although up to 50% of African green monkeys (AGMs) are infected by simian immunodeficiency viruses (SIV) in their natural habitat, they remain asymptomatic carriers of these lentiviruses. They provide an attractive model to study not only the origin but also the link among genetic variation, host-virus adaptation, and pathogenicity of primate lentiviruses. SIVagm have been isolated from three species of AGM: the vervet (Cercopithecus pygerythrus), the grivet (Cercopithecus aethiops), and the sabaeus (Cercopithecus sabaeus) monkey. We studied four new SIVagm isolates from a fourth AGM species, the tantalus monkey (Cercopithecus tantalus), caught in the Central African Republic, and four new isolates from feral sabaeus monkeys from Senegal. Antigenic properties and partial env sequences were used to evaluate the diversity among these isolates. Alignment of env sequences in SIVagm isolated from tantalus and sabaeus monkeys permitted detailed mapping of the variable and conserved domains in the external glycoprotein. Genetic distances indicated that SIVagm isolates from tantalus monkeys are the most divergent among SIVagm in feral AGMs in Africa. The fact that AGMs are infected by four distinct lentiviruses, each specific for a single AGM species, supports the hypothesis of a coevolution of these viruses and their natural hosts and suggests that SIV transmission is a rare event among separated AGM species in the wild.

Amino Acid Sequence↗

PubMed1992

A method for delineating structurally homogeneous regions in protein sequences.

A homogeneous region in a protein sequence is a set of contiguous residues that share common features, concerning physico-chemical, structural and mutational information. This paper presents a method for identifying such homogeneous regions. From a profile describing a given type of biological information along the sequence, the algorithm allows the segmentation of the sequence by optimizing a criterion characterized by two user-defined control parameters: the 'homogenizing degree' of the regions and the 'site neighbourhood' size. We apply the method to the envelope proteins of the human immunodeficiency virus HIV-1, for the identification of homogeneous regions in a hydrophobicity profile and the delineation of variable and conserved regions in a variability profile.

Algorithms↗

PubMed1991

MASH: an interactive program for multiple alignment and consensus sequence construction for biological sequences.

This paper presents a method for the multiple alignment of a sequence set. The MASH algorithm uses a non-redundant database of common motifs and an 'alignment priority' criterion that depends on the length and the occurrence frequency of the patterns in the set of sequences. This user-defined criterion allows the determination of the series of the patterns to be aligned. This program is applied to a fragment of envelope gene env gp120 for 20 isolates of the immunodeficiency virus. The multiplicity of alignments obtained by modifying the criterion parameters reveals different aspects of similarity between the sequences.

Algorithms↗

PubMed1991

'Size leap' algorithm: an efficient extraction of the longest common motifs from a molecular sequence set. Application to the DNA sequence reconstruction.

We propose a new method, called 'size leap' algorithm, of search for motifs of maximum size and common to two fragments at least. It allows the creation of a reduced database of motifs from a set of sequences whose size obeys the series of Fibonacci numbers. The convenience lies in the efficiency of the motif extraction. It can be applied in the establishment of overlap regions for DNA sequence reconstruction and multiple alignment of biological sequences. The method of complete DNA sequence reconstruction by extraction of the longest motifs ('anchor motifs') is presented as an application of the size leap algorithm. The details of a reconstruction from three sequenced fragments are given as an example.

Algorithms↗

PubMed1990

[Blepharoplasty: various technics in surgery of eyelid aging].

The authors reviewing their own experience of blepharoplasty (92 cases) over the last ten years, discuss the principal approaches used depending on the age of the patient, the amount of adipose tissue, the lower lid tarsal and muscular laxity and the quality of the skin excess. In the lower eyelid they emphasize the value of the transconjunctival approach in young and or coloured people and the use of a cutaneo-muscular flap in the classical technique. In the upper eyelid, they combine the skin excision with an orbicularis muscle strip and in old people with suspension of the lateral canthus. A wise selection of these various approaches avoids the rare complications (ectropion and scleral show) because blepharoplasty must be considered to be a "variable geometry" operation.

Adult↗

PubMed1990

["Delta" cartilaginous graft in secondary or post traumatic rhinoplasty].

The authors study some cases of surgical revision in post traumatic or secondary rhinoplasty. Cartilaginous grafts with temporal superficialis fascia are recommended. The removal of ear cartilage is used by a posterior approach for the concha cartilage associated with a septum or an alar cartilage removal. They describe the Delta graft associating a concha cartilage supported by a prop (auricular or septal) to repair a loss of substance from the middle or lower third of the nasal pyramid.

Adult↗

PubMed1990

[Blepharoplasties. Different techniques of surgery].

The authors, reviewing their own experience of Blepharoplasty (92 cases) since ten years, discuss the principal approaches used depending on the age of the patient, the amount of adipose tissue, the lower lid tarsal and muscular laxity and the quality of the skin excess. On the lower eye lid they emphasize the interest of the transconjunctival approach in young an or coloured people and they undermine a cutaneo-muscular flap in the classical technique. On the upper eye lid, they combine the skin excision with an orbicular muscle strip and in old people with a suspension of the lateral canthus. A good choice between these different approaches avoid the rare complications (ectropion and scleral show) because blepharoplasty must be considered like a "variable geometry" operation.

Age Factors↗

PubMed1989

Different technical approaches for blepharoplasty in eyelid rejuvenation surgery.

The authors have reviewed their clinical experiences with 92 cases of blepharoplasties treated during the past 10 years and discuss the principal approaches used, depending on the age of the patient, the amount of adipose tissue present, the degree of lower lid tarsal and muscle laxity present, and the quality of the skin excess encountered. On the upper eyelid, skin excision is combined with an orbicular muscle strip and in older patients a suspension of the lateral canthus. On the lower eyelid the transconjunctival approach is emphasized in young and or colored patients, using an undermined musculocutaneous flap in the classical technique. A good choice between these different approaches avoids the rare complications of ectropion and scleral show because the procedure used is considered to be a variable "geometric" operation.

Blepharoptosis↗