Patients with localized juvenile periodontitis (LJP) have elevated levels of immunoglobulin G2 (IgG2) in their sera. This is also observed in vitro when peripheral blood leukocytes from LJP patients are stimulated with pokeweed mitogen. In previous studies, we showed that lymphocytes from subjects with no periodontitis (NP subjects) produced substantial amounts of IgG2 when they were cultured with monocytes from LJP patients (LJP monocytes). These observations indicate that monocytes or monocyte-derived mediators are positive regulators of the production of IgG2. The present study was initiated to determine if secreted factors from LJP monocytes were capable of enhancing IgG2 production and to determine if prostaglandin E2 (PGE 2 ), which LJP monocytes produce at elevated levels, enhances IgG2 production. Experiments in a transwell system and with monocyte-conditioned media indicated that cell-cell contact was not necessary for LJP monocytes to augment the production of IgG2 by T and B cells from NP subjects. Moreover, the production of IgG2 was selectively induced by the addition of PGE 2 or platelet-activating factor (PAF), another lipid cytokine, which can elevate PGE 2 synthesis. Furthermore, IgG2 production was abrogated when cells were treated with indomethacin, a cyclooxygenase inhibitor that blocks the synthesis of PGE 2 , or the PAF antagonists CV3988 and TEPC-15. The effects of indomethacin were completely reversed by PGE 2 , indicating that this is the only prostanoid that is essential for the production of IgG2. Similarly, PGE 2 reversed the effects of a PAF antagonist, suggesting that the effects of PAF are mediated through the induction of PGE 2 synthesis. Together, these data indicate that PGE 2 and PAF are essential for the production of IgG2.Recent results suggest that early-onset periodontitis (EOP) patients have a genetic predisposition to develop disease early in life (22). The clinical manifestations of EOP are variable. Even in the same family, some patients may have a localized form restricted to first molars and incisors (localized juvenile periodontitis [LJP]) and others a severe generalized form. It is likely that these differences in clinical expression are related to several factors, including differences in microbial flora and differences in the host response. Serum total immunoglobulin G2 (IgG2) levels in LJP patients are significantly elevated over those in race-and age-matched controls with no periodontitis (NP controls) (21). Much of this IgG2 antibody is directed against Actinobacillus actinomycetemcomitans serotype b, a putative etiologic agent for EOP, and Porphyromonas gingivalis, which is also associated with EOP (8,20,36,37). The immunodominant antigens of these organisms are the serotype-specific carbohydrates, and, for A. actinomycetemcomitans, the carbohydrate is a high-molecular-weight form of lipopolysaccharide (LPS) (7,8,35,36). Compared to NP subjects, EOP patients frequently have very high titers of IgG2 reactive with the high-molecular-weight A. actinomycetemcomita...

Susceptibility to early‐onset periodontitis (EOP) appears to be attributable to a gene inherited in an autosomal dominant pattern. This explains why EOP clusters in families and why about half of the family members develop periodontal disease early in life. Manifestation of EOP is variable, with some patients having a localized form restricted to first molars and incisors (LJP) and others with a severe generalized form of periodontitis (SP). The extent and severity of disease is less in patients who are seropositive for Actinobacillus actinomycetemcomitans than in seronegative patients, and this relationship prompted the hypothesis that anti‐A. actinomycetemcomitans helps limit disease. The dominant antibody is an IgG2 reactive with the serotypespecific carbohydrate. The incidence of the LJP form of EOP is about 10 times higher in blacks than in whites. Interestingly, blacks have higher levels of serum IgG2, a higher frequency of anti‐A. actinomycetemcomitans antibody, and higher serum titers of IgG2 anti‐A. actinomycetemcomitans which may help explain why the disease is localized. Studies in progress suggest that smoking reduces serum IgG2 levels in SP patients and is associated with more severe periodontal destruction. In marked contrast, IgG2 does not appear to be reduced in LJP patients who smoke, and smoking does not appear to increase periodontal destruction. We think that IgG2 anti‐A. actinomycetemcomitans is playing a role in limiting the extent and severity of disease in patients genetically susceptible to EOP. J Periodontol 1996;67:317–322.

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This study demonstrates that DLQI and PASI remain low after 12 months, and, in fact, both gradually decline further with time. Patients on biologic agents for prolonged periods maintained their improvement in QoL for up to 6.5 years.

Purpose This study aims to explore the association between internet addiction and problem behaviours on social networking sites (SNS) using the general strain theory (Agnew, 1992). Design/methodology/approach Using the purposive sampling method, a survey was conducted, which collected data from 414 college students studying in two public universities in South Australia. The Delphi method was used to develop the questionnaire used for the survey. Findings 'Results of this research indicated a significant association between internet addiction and problem behaviours on SNS. Respondents who had engaged in problem behaviours on SNS had high internet addiction test scores (Young, 1998). On the basis of this finding, the present research argues that the general strains associated with the suffering of newly emerging challenges such as internet addiction might contribute to victimisation and deviant and problem behaviours on SNS in specific and possibly in cyberspace in general. Research limitations/implications Results of the present study need to be interpreted cautiously due to many limitations it has. This research is a cross-sectional study, which might not adequately explain the associations between internet addiction and problem behaviours on SNS. Longitudinal studies involving larger samples might have added significant value to this study. The present study uses purposive sampling technique, which has limited its generalizability, and its findings may not be generalised to large populations. Originality/value Limited information is available pertaining to the association between problem behaviours on SNS and internet addiction. The present study is a pioneering effort, which argues that rapid popularity of SNS is likely to increase internet addiction and the frustration of not getting proper treatment for their internet addiction might lead to deviant behaviours on SNS.