Patterns of periodontal disease progression based on linear mixed models of clinical attachment loss.

AIM: The goal of the present longitudinal cohort study was to examine patterns of periodontal disease progression at progressing sites and subjects defined based on linear mixed models (LMM) of clinical attachment loss (CAL). MATERIALS AND METHODS: A total of 113 periodontally healthy and 302 periodontitis subjects had their CAL calculated bimonthly for 12 months. LMMs were fitted for each site and the predicted CAL levels used to categorize their progression state. Participants were grouped based on the number of progressing sites into unchanged, transitional and active subjects. Patterns of periodontal disease progression were explored using descriptive statistics. RESULTS: Progression occurred primarily at molars (50% of progressing sites) and inter-proximal sites (72%), affected a higher proportion of deep than shallow sites (2.7% versus 0.7%), and pocketing was the main mode of progression (49%). We found a low level of agreement (47%) between the LMM and traditional approaches to determine progression such as change in CAL ≥3 mm. Fourteen per cent of subjects were classified as active and among those 93% had periodontitis. The annual mean rate of progression for the active subjects was 0.35 mm/year. CONCLUSION: Progressing sites and subjects defined based on LMMs presented patterns of disease progression similar to those previously reported in the literature.

Modelling changes in clinical attachment loss to classify periodontal disease progression.

AIM: The goal of this study was to identify progressing periodontal sites by applying linear mixed models (LMM) to longitudinal measurements of clinical attachment loss (CAL). METHODS: Ninety-three periodontally healthy and 236 periodontitis subjects had their CAL measured bi-monthly for 12 months. The proportions of sites demonstrating increases in CAL from baseline above specified thresholds were calculated for each visit. The proportions of sites reversing from the progressing state were also computed. LMM were fitted for each tooth site and the predicted CAL levels used to categorize sites regarding progression or regression. The threshold for progression was established based on the model-estimated error in predictions. RESULTS: Over 12 months, 21.2%, 2.8% and 0.3% of sites progressed, according to thresholds of 1, 2 and 3 mm of CAL increase. However, on average, 42.0%, 64.4% and 77.7% of progressing sites for the different thresholds reversed in subsequent visits. Conversely, 97.1%, 76.9% and 23.1% of sites classified as progressing using LMM had observed CAL increases above 1, 2 and 3 mm after 12 months, whereas mean rates of reversal were 10.6%, 30.2% and 53.0% respectively. CONCLUSION: LMM accounted for several sources of error in longitudinal CAL measurement, providing an improved method for classifying progressing sites.

A unique family of proteins associated with internalized membranes in protein storage vacuoles of the Brassicaceae.

The protein storage vacuole (PSV) is a specialized organelle in plant seeds that accumulates storage proteins and phytate during seed development. In many plant species, such as tomato and tobacco, the PSV contains two types of microscopically visible intra-organellar inclusions: a large crystalline lattice of membranes and proteins, the crystalloid, and one or a few large phytate crystals, the globoids. In seeds of the family Brassicaceae, the PSVs lack visible crystalloids and have many small globoids dispersed throughout. We biochemically fractionated PSVs from Brassica napus and defined a crystalloid-like fraction that contained integral membrane protein markers found in crystalloids of other plants. Protein analyses identified a previously undescribed family of proteins, the Brassicaceae PSV-embedded proteins (BPEPs), associated with 'crystalloid' and globoid fractions. The defining characteristics of the BPEPs are an N-terminal signal peptide and tandem MATH domains, which may mediate protein-protein interactions. Database analyses indicated that the BPEPs are unique to Brassicaceae. Immunofluorescence studies using anti-BPEP antibodies and antibodies to other biochemical markers to label B. napus and Arabidopsis thaliana seed sections localized the BPEPs to structures within the PSVs, whose appearance was consistent with a diffuse network of internalized membranes and globoids. These results demonstrate that Brassicaceae PSVs contain internalized membranes, and raise the possibility that BPEPs modify these internal membrane structures to yield a PSV morphology different from that of tomato or tobacco.

Effect of television advertisements for foods on food consumption in children.

The impact of television (TV) advertisements (commercials) on children's eating behaviour and health is of critical interest. In a preliminary study we examined lean, over weight and obese children's ability to recognise eight food and eight non-food related adverts in a repeated measures design. Their consumption of sweet and savoury, high and low fat snack foods were measured after both sessions. Whilst there was no significant difference in the number of non-food adverts recognised between the lean and obese children, the obese children did recognise significantly more of the food adverts. The ability to recognise the food adverts significantly correlated with the amount of food eaten after exposure to them. The overall snack food intake of the obese and overweight children was significantly higher than the lean children in the control (non-food advert) condition. The consumption of all the food offered increased post food advert with the exception of the low-fat savoury snack. These data demonstrate obese children's heightened alertness to food related cues. Moreover, exposure to such cues induce increased food intake in all children. As suggested the relationship between TV viewing and childhood obesity appears not merely a matter of excessive sedentary activity. Exposure to food adverts promotes consumption.