BackgroundLow and middle income countries are ageing at a much faster rate than richer countries, especially in Asia. This is happening at a time of globalisation, migration, urbanisation, and smaller families. Older people make significant contributions to their families and communities, but this is often undermined by chronic disease and preventable disability. Social participation can help to protect against morbidity and mortality. We argue that social participation deserves much greater attention as a protective factor, and that older people can play a useful role in the prevention and management of chronic conditions. We present, as an example, a low-cost, sustainable strategy that has increased social participation among elders in Sri Lanka.DiscussionCurrent international policy initiatives to address the increasing prevalence of non-communicable chronic diseases are focused on cardiovascular disease, diabetes, respiratory disease and cancers, responsible for much premature mortality. Interventions to modify their shared risk factors of high salt and fat diets, inactivity, smoking and alcohol use are advocated. But older people also suffer chronic conditions that primarily affect quality of life, and have a wider range of risk factors. There is strong epidemiological and physiological evidence that social isolation, in particular, is as important a risk factor for chronic diseases as the 'lifestyle' risk factors, yet it is currently neglected. There are useful experiences of inexpensive and sustainable strategies to improve social participation among older people in low and lower middle income countries. Our experience with forming Elders' Clubs with retired tea estate workers in Sri Lanka suggests many benefits, including social support and participation, inter-generational contact, a collective voice, and facilitated access to health promotion activities, and to health care and social welfare services.SummaryPolicies to address the increase in chronic non-communicable diseases should include consideration of healthy ageing, conditions that affect quality of life, and strategies to increase social participation. There are useful examples showing that it is feasible to catalyse the formation of Elders' Clubs or older people's associations which become self-sustaining, promote social participation, and improve health and well-being of elders and their families.

Gingival crevicular fluid is an inflammatory exudate derived from the periodontal tissues. It is composed of serum and locally generated materials such as tissue breakdown products, inflammatory mediators, and antibodies directed against dental plaque bacteria. It plays a special part in maintaining the structure of junctional epithelium and the antimicrobial defense of periodontium. Some of the suspected periodontal pathogens such as Porphyromonas gingivalis and Treponema denticola produce broad-spectrum neutral proteinases as part of their virulence arsenal. These proteinases may be detected in plaque and gingival crevicular fluid samples of patients with periodontitis. The potential diagnostic importance of gingival fluid was recognized more than six decades ago. The fluid component of gingival crevicular fluid is derived primarily from microvascular (postcapillary venule) leakage. There are number of distinct advantages and challenges of using gingival crevicular fluid as a diagnostic test for periodontal disease.

Abstract. In recent decades, extensive mortality of reef-building corals throughout the Caribbean region has led to the erosion of reef frameworks and declines in biodiversity. Using field observations, structural models, and high-precision U–Th dating methods, we quantify changes in structural complexity in the major framework-building coral Orbicella annularis over a 20-year period at Long Caye (Belize). Despite extensive mortality following the mass coral bleaching event of 1998, the structural complexity of frameworks remained largely unchanged between 1998 (rugosity index, R, of 2.35±0.1) and 2018 (R of 2.29±0.1). Colony-scale structural complexity was maintained, as the rapid growth of surviving ramets (0.69±0.1 cm yr−1) offset the slower bioerosion of dead ramets (-0.11±0.16 cm yr−1). Despite the apparent stability of the structural complexity at colony scales, bioerosion of individual dead ramets over 2 decades led to declines in microhabitat complexity, with an overall reduction in the depth of microhabitats within frameworks. Altered microhabitat complexity appears to have negative effects on cryptic fauna, with the grazing urchin Echinometra viridis declining from 1.5±0.4 individuals m−2 in 1998 to 0.02± individuals m−2 in 2018. Changes in microhabitat complexity have the potential to alter ecological interactions that can impact recovery dynamics on coral reefs in ways that are undetectable using traditional rugosity metrics of structural complexity.

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