Experimental gingivitis around deciduous teeth in children with Down's syndrome

Abstract. Epidemiological studies have shown that there is a high prevalence and rapid progression of periodontal disease in children with Down's Syndrome (DS). In this respect, DS children exhibit a markedly different response compared with healthy children. In order to understand the reasons for this difference, a controlled study was set up to determine the extent and the quality of the differences in the early periodontal tissue response towards dental plaque in the deciduous dentition of DS children and matched control children. In a preliminary investigation, the gingival health was estimated by determining the bleeding tendency. 9 healthy children were selected from a group of 14 and matched with 9 DS children with respect to plaque development, sulcus depth and age. The DS children had a higher bleeding tendency than the matched controls. In the DS children, moreover, a correlation was found between bleeding tendency and age. No such correlation was found in the controls. After a period of intensive oral hygiene, all cleaning of teeth was discontinued for 21 days. The amount of plaque according to the plaque index, the gingival health according to the gingival index, and the amount of crevicular leucocytes and gingival exudate were assessed at days 0, 7, 14 and 21. During the experimental phase of the study, the amount of plaque increased at a similar rate in both groups. In the DS children, the development of gingival inflammation started earlier and was more extensive. It increased after day 14, whereas in the control children, the gingival inflammation seemed to stabilize at this time. The results of the present experimental study thus confirm earlier results from epidemiological studies. The amount of gingival exudate was very low in both groups, but in the DS group it increased after day 14. In contrast to the DS children, the amount of crevicular leukocytes increased significantly in the control children from day 0 to day 21, the highest score being found on day 14. On day 7, a significantly larger amount of crevicular leucocytes was found in the DS children than in the controls. The findings of this study suggest that DS children have a different leucocyte response together with a more extensive gingival inflammation than normal children.     

Detection of sodium ions in anisotropic environments through spin-lock NMR.

A new method for selectively detecting sodium ions in anisotropic environments is presented. A spin-lock (SL) sequence, followed by a coherence transfer pulse, generates rank-two zero-quantum coherences, and converts them into observable transverse magnetization. The quadrupolar polarization is only generated when there are residual quadrupolar couplings in the sample, and provided the SL field strength is comparable to these couplings. This filter has proved to be more efficient than a double-quantum magic-angle (DQ-MA) filter in generating observable signal from ions in anisotropic media in both a nasal bovine cartilage sample and a liquid crystalline DNA sample. Finally, the SL filtering technique does not rely on a flip angle effect for the selection of the desired signal component, as does a DQ-MA filter, and may therefore prove desirable in an imaging experiment, due to its better tolerance to phase and flip angle imperfections.     

Socioeconomic differences in lung cancer incidence: a systematic review and meta-analysis

Objective  To investigate the associations between various socioeconomic indicators and lung cancer incidence. Methods  We searched PubMed and EMBASE databases for studies on socioeconomic position (SEP) and lung cancer incidence published through October 2007. Random-effect model was used to pool the risk estimates from the individual studies. We stratified the analysis by adjustment strategy to investigate the influence of smoking on socioeconomic gradient in lung cancer incidence. Results  Out of 3,288 citations, we identified 64 studies eligible for inclusion. Compared to the highest SEP level, we observed an overall increased risk in lung cancer incidence among people with low educational SEP (61%), low occupational SEP (48%), and low income-based SEP (37%). The negative social gradient for lung cancer incidence remained for most of the possible sets of pooled estimates obtained in subgroup analyses for occupational and educational SEP with less consistency for SEP based on income in studies adjusted and unadjusted for smoking. No evidence of publication bias was apparent. Conclusion  Lung cancer incidence was associated with low educational, occupational, and income-based SEP. The association, adjusted or unadjusted for smoking, points out the importance of social position to be addressed in all discussions on cancer preventive measures. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. This work was performed in the Department of Public Health Sciences, Division of Social Medicine/Epidemiology, Karolinska Institutet, Stockholm, Sweden.     

Analysis of pethidine disposition in the pregnant rat by means of a physiological flow model

The disposition of pethidine (meperidine) in the pregnant rat is described by means of a physiological flow model. The model includes arterial and venous blood, brain, fat, fetal, hepatic, intestinal, muscular, pulmonar, and renal tissues. The concentration-time profiles of pethidine calculated by the model are consistent with experimental data, except for the brain and renal tissues, where the model predicts initially higher concentrations. Simulations are carried out to further explore the contribution from different organs on the kinetics in blood and tissues. The tissue-to-blood partition coefficients vary over a range from 5 to 316, where fat has the lowest and liver the highest after a correction is made due to hepatic extraction. Rapid uptake occurs into highly perfused organs such as brain, kidneys, liver, and lungs, followed by fetus, intestines, muscle, and fat. Data indicate no marked membrane resistance to pethidine of the investigated organs, except for fetal tissues, but rather a perfusion-limited uptake. Simulations suggest that muscles and adipose tissue play an important role in the rat, becoming the major reservoir of drug during the intermediate and terminal elimination phase, respectively. Volume of distribution and the biological half-life agree with reported findings. Pethidine is subject to a high systemic blood clearance, which exceeds the total hepatic blood flow in the rat. No degradation of pethidine is found in blood, and therefore a pulmonary expression for pethidine clearance is added as a potential source of pethidine elimination. The elimination of pethidine after a single i.v. bolus dose is found to be dependent on simulated changes in cardiac output and hepatic blood flow. A simulation is performed with the scaled model to mimic the human concentration-time profiles in maternal blood and brain tissues and fetal tissue during repetitive doses of pethidine.