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Biomedical subjects

M Sixou

Publications and source records attributed to M Sixou.

9 recordsLinked to original sources
PubMed1999

Neutrophil dysfunctions, IL-8, and soluble L-selectin plasma levels in rapidly progressive versus adult and localized juvenile periodontitis: variations according to disease severity and microbial flora.

We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of whole-blood polymorphonuclear neutrophils (PMN) from 26 patients with periodontitis. Three different clinical entities were studied: adult periodontitis (AP), localized juvenile periodontitis (LJP), and rapidly progressive periodontitis (RPP). Unstimulated PMN from the patients showed reduced Lewis x, sialyl-Lewis x, and L-selectin expression relative to those from healthy control subjects. These alterations were present whatever the severity of periodontal disease. However, PMN from RPP patients showed increased basal H2O2 production and decreased L-selectin shedding. These latter impairments, which correlated with increased IL-8 plasma levels, could contribute to initial vascular damage. In addition, decreased IL-8 priming of H2O2 production by PMN from RPP patients could account for a lower bactericidal capacity of PMN, leading to the large number of bacteria in the subgingival region of RPP patients. Soluble L-selectin plasma levels were also decreased in the RPP group, indicating more severe or diffuse endothelial damage. These abnormalities were not found in the patients with less destructive forms of periodontitis (AP and LJP). Porphyromonas gingivalis, a bacterial pathogen known to increase IL-8 production by PMN, was found in the periodontal pockets of RPP patients only. These results show links among PMN abnormalities, the clinical form of periodontitis, and the gingival bacterial flora.

Adolescent↗
PubMed1998

Characterization of lymphocyte subpopulations in periapical lesions by flow cytometry.

The mechanisms by which the bacterial root-canal infection leads to periapical bone destruction (cysts or granulomas) are not yet well understood. Previous works have shown elements of an active immune response in the lesions. In the present study, flow cytometry was used to improve the characterization of immune cells. Semiquantitative immunohistochemical analysis showed the presence of plasma cells, macrophages and B and T cells. The simultaneous use of several antibodies in flow cytometry allowed a more precise phenotype of the lymphocytes. The cysts displayed an abundance of B lymphocytes at the same time as a relative scarcity of CD8+ cells. CD4+ lymphocytes were the dominant lymphocyte population in most cases. A small number of gamma delta T lymphocytes and natural killer cells was found. These preliminary results show that flow cytometry may be used to characterize immune cells from inflamed tissue and opens the possibility for further functional studies.

Adult↗
PubMed1994

Specific genetic variants of Actinobacillus actinomycetemcomitans correlate with disease and health in a regional population of families with localized juvenile periodontitis.

A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile periodontitis (LJP), and 35 healthy control subjects was monitored, over a 5-year period, for the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Restriction fragment length polymorphism (RFLP) analysis was used to monitor the distribution of genetic variants of this bacterium in LJP-susceptible subjects that converted from a healthy to a diseased periodontal status. A. actinomycetemcomitans was cultured from 57% of the LJP family members accessioned into the study. Nine of 36 LJP-susceptible subjects, in seven families, developed signs of periodontal destruction. All but one of these conversion subjects harbored A. actinomycetemcomitans. Bacterial variants representative of a single RFLP group (II) showed the strongest correlation with conversion (P < 0.002). Six of nine conversion subjects were infected with A. actinomycetemcomitans from this group. RFLP group II variants also prevailed in 8 of 22 probands but were absent in the 35 healthy control subjects. In contrast to the selective distribution of group II variants is diseased individuals, variants belonging to RFLP groups XIII and XIV were found exclusively in the control subjects. Thus, the use of RFLP to type clinical isolates of A. actinomycetemcomitans has resulted in the identification of genetic variants that predominate in LJP and health. These results indicate that studies concerned with the pathogenicity of this bacterium in LJP should be focused on the group II variants.

Adult↗
PubMed1992

[The adhesion of Actinobacillus actinomycetemcomitans to oral epithelial cells].

Adherence is a major pathogenicity factor for many bacteria. The aim of this study was to measure the adherence potential of Actinobacillus actinomycetemcomitans (A.a.) for buccal epithelial cells (BEC). In the second part of the study, the inhibitory potential of saliva on adherence between A.a. and BEC was tested. Saliva specimens were obtained from three groups of subjects: a group of normal subjects (NS), a group of subject with localized juvenile periodontitis (LJPS) and a group of subjects with adult periodontitis (APS). Clinical strains of A.a. showed a major adherence potential for BEC (25.5 A.a./BEC). In contrast, reference strains of bacteria appeared to possess a much lower potential for adherence (12.6 A.a./BEC). Saliva samples taken from from the LJPS and APS group had a high inhibitory adherence potential, since in each of these groups a reduction of 60.9% and 66.7% respectively, was observed in the number of bacteria adhering to BEC.

Adolescent↗
PubMed1991

[A comparison between 4 subgingival bacteriologic sampling technics].

A comparative study of four classical techniques employed in the sampling of subgingival microflora (paper points, swabbing, curette and washing followed by aspiration) has been carried out. This study was based upon quantitative criteria (number of bacteria sampled) and qualitative criteria (number of morphologically distinct colonies found per sampling technique). Sampling was done on three different groups of patients: a control group, a group of patients with gingivitis and a group of patients with periodontitis. The curette sampling technique was found to be efficient both quantitatively and qualitatively. Difficulties in standardizing this method however were encountered with the failure to achieve reproducible results. For this reason the technique of paper point was preferred. This method was found to be more reliable and reproducible in each of the three groups of patients sampled.

Adult↗
PubMed1991

[The transmission of Actinobacillus actinomycetemcomitans between spouses].

The aim of this investigation was to study the transmission of Actinobacillus actinomycetemcomitans (A.a) between husband and wife when one of them was affected by acute juvenile periodontitis (P.A.J.). The hypothesis tested was the role played by the reservoir of the non-infected partner in explaining the frequent recurrences of the disease in the affected spouse despite combined antibiotherapeutical and surgical treatments. Twenty subjects with P.A.J. were studied. A.a. was found in the sub-gingival flora of nineteen of them. This micro-organism was also isolated in each of the partners of the nineteen patients. Each couple presented strains of the same biotype. The serotypes were studied in seven of these couples and confirmed the results of the biotypes. All theses results are in favour of the transmission of A.a. between partners.

Actinobacillus↗
PubMed1991

[The distribution and prevalence of Haemophilus actinomycetemcomitans in the oral cavity].

The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 specimens of subgingival plaque on the four subgingival aspects of all teeth of the dental arch, 150 specimens from the mucosal surface (tongue and cheek) and 30 saliva specimens in 30 subjects. The sample population of 30 subjects was subdivided into three groups: 10 normal subjects, 10 subjects with localised juvenile periodontitis (SLJP) and 10 subjects with adult chronic periodontitis (SACP). The prevalences of H.a. in subgingival areas of each group mentioned were 30%, 90% and 60% respectively. Scores for prevalence obtained with other types of specimens proved to be lower except for saliva specimens which appear to be a less representative marker of subgingival prevalence of H.a.. Histograms for the distribution of H.a. revealed a predominance of this microorganism on the proximal surface of molar teeth in the three groups of patients. Only the SLJP also exhibited a high prevalence on the proximal aspect of the incisor teeth. The wide distribution of H.a. in all of the clinical groups studied suggests that this bacterium is not a good marker of periodontal disease and that it is necessary to define the most characteristic phenotypes and genotypes.

Actinobacillus Infections↗