Induction of IL-6 and MMP-8 in human periodontal fibroblasts by static tensile strain

Objectives

Mechanical loading is a potential activator of inflammation and able to stimulate factors for periodontal and alveolar bone destruction. Aim of this study was to investigate the inflammatory response and synthesis of proteinases by human periodontal ligament fibroblast (HPdLF) dependent on different strengths of static tensile strain (STS).

Materials and methods

HPdLFs were loaded with different STS strengths (1, 5, and 10 %) in vitro. Gene expressions of cyclooxygenase (COX)-2 and interleukin (IL)-6 were analyzed by quantitative real-time polymerase chain reaction. Production of IL-6, prostaglandin E₂ (PGE₂), matrix metalloproteinase (MMP)-8, and tissue inhibitors of matrix metalloproteinase (TIMP)-1 were measured by enzyme-linked immunosorbent assay. Receptor activator of nuclear factor-kappa ligand (RANKL) synthesis was detected by immunocytochemical staining.

Results

Ten percent STS led to an increased gene expression of IL-6 and COX-2 (34.4-fold) in HPdLF, and 1 and 5 % STS slightly reduced the gene expression of IL-6. Synthesis of IL-6 was significantly reduced by 1 % STS and stimulated by 10 % STS. Ten percent STS significantly induced PGE₂ production. RANKL was not detectable at any strength of STS. MMP-8 synthesis showed significantly higher values only at 10 % STS, but TIMP-1 was stimulated by 5 and 10 % STS, resulting into highest TIMP-1/MMP-8 ratio at 5 % STS.

Conclusions

High-strength STS is a potent inducer of periodontal inflammation and MMP-8, whereas low-strength STS shows an anti-inflammatory effect. Moderate-strength STS causes the highest TIMP-1/MMP-8 ratio, leading to appropriate conditions for reformation of the extracellular matrix.

Clinical relevance

Furthermore, this study points out that the strength of force plays a pivotal role to achieve orthodontic tooth movement without inducing periodontal inflammation and to activate extracellular matrix regeneration.     

Capacity building in health economics. Opportunities for training in developing countries

This paper provides an overview of the opportunities available for training in health economics in the regions of Africa, Asia and Latin America, following a WHO forum on Capacity Building in Health Economics held in Geneva in December 1995. It describes in brief the training opportunities available throughout Asia, Africa and Latin America. It then gives a detailed resume of courses available for students and professionals at Chulanlongkorn University, Thailand, the University of Cape Town, South Africa and the University of the West Indies, Trinidad. It also describes the international and regional networks which have developed and now provide further opportunities for training. The final section of this paper looks to the future and suggests that although continued financial and academic support will be needed from the countries of the North, the development of regional capacities in health economics should be as much as possible through regional resources, and regional strategies should be a priority.     

Eating problems and interpersonal functioning among several groups of women

This paper examines the relationship between eating disorders and problems in interpersonal functioning. Questionnaires that measure eating problems, interpersonal adjustment, and general neuroticism were completed by several groups of women: anorexic patients, persons whose interests or occupations involved a concern about bodily shape or condition (dancers, models, and athletes), and members of the general public. A substantial and significant relationship was found between eating symptomatology and interpersonal functioning in all groups. However, this association survived only in the anorexic patient group when general neuroticism was partialled out. We take this to imply that psychosocial difficulties are unlikely to play a strong role in the initial development of eating problems.