The distribution of plaque and gingivitis and the influence of toothbrushing hand in a group of South Wales 11–12 year-old children

Numerous factors may affect the distribution of plaque and gingivitis in any individuals mouth. Of considerable importance must be the oral hygiene habits of each person, which will be influenced by compliance and dexterity with tooth cleaning methods. The pattern of gingivitis seen at a young age may, with time, reflect the eventual distribution of attachment loss. This in part, could explain the considerable variation in chronic periodontal disease seen between individuals and at different sites within the same mouth. This study reports the baseline data for the distribution of plaque and gingivitis in 1105, 11-12-year-old children in South Wales. The children were selected by disproportionate stratified random sampling and examined by a multidisciplinary group with the long-term aim of evaluating the importance of malocclusion to dental health and psychosocial variables. Toothbrushing frequency had a very low but significant correlation with the distribution of plaque and gingivitis, accounting therefore for only a small % of the variance in the group. For the total group and right-handed toothbrushers, buccal plaque and gingivitis was significantly increased on right contralateral teeth. No specific pattern for plaque and gingivitis distribution by side was seen for 100 left-handed toothbrushers. Plaque and gingivitis also showed significant differences dependent upon arch, tooth number, and surface. The population is being followed at 4-year intervals to monitor the pattern of periodontal disease with time and correlate changes with these baseline findings.     

Selected Nonpharmacological Therapies for Chronic Pain: The Therapeutic Use of the Placebo Effect

Chronic pain is a common problem requiring a multidisciplinary approach. Nursing can offer diverse therapies complementary to the medical-surgical approach. Guidelines for practice and challenges for research are outlined for selected nonpharmacological chronic pain therapies. This article discusses the placebo effect, which is common to all therapies. Placebos can therapeutically empower patients to stimulate their psychophysiologic self-regulation abilities. Effects, theories, ethics, and therapeutic methods of stimulating the placebo effect are explored.     

Exposure to power frequency electric fields and the risk of childhood cancer in the UK

The United Kingdom Childhood Cancer Study, a population-based case-control study covering the whole of Great Britain, incorporated a pilot study measuring electric fields. Measurements were made in the homes of 473 children who were diagnosed with a malignant neoplasm between 1992 and 1996 and who were aged 0-14 at diagnosis, together with 453 controls matched on age, sex and geographical location. Exposure assessments comprised resultant spot measurements in the child's bedroom and the family living-room. Temporal stability of bedroom fields was investigated through continuous logging of the 48-h vertical component at the child's bedside supported by repeat spot measurements. The principal exposure metric used was the mean of the pillow and bed centre measurements. For the 273 cases and 276 controls with fully validated measures, comparing those with a measured electric field exposure >/=20 V m(-1) to those in a reference category of exposure <10 V m(-1), odds ratios of 1.31 (95% confidence interval 0.68-2.54) for acute lymphoblastic leukaemia, 1.32 (95% confidence interval 0.73-2.39) for total leukaemia, 2.12 (95% confidence interval 0.78-5.78) for central nervous system cancers and 1.26 (95% confidence interval 0.77-2.07) for all malignancies were obtained. When considering the 426 cases and 419 controls with no invalid measures, the corresponding odds ratios were 0.86 (95% confidence interval 0.49-1.51) for acute lymphoblastic leukaemia, 0.93 (95% confidence interval 0.56-1.54) for total leukaemia, 1.43 (95% confidence interval 0.68-3.02) for central nervous system cancers and 0.90 (95% confidence interval 0.59-1.35) for all malignancies. With exposure modelled as a continuous variable, odds ratios for an increase in the principal metric of 10 V m(-1) were close to unity for all disease categories, never differing significantly from one.     

Ischaemic episodes of less than 5 minutes produce preconditioning but not stunning in the isolated rat heart

The aim of the present study was to examine whether ischaemic episodes of less than 5 min could induce preconditioning or stunning in the isolated rat heart. Hearts were subjected to total global ischaemia of 1, 2 and 4 min followed by 10 min of reperfusion before an 18-min main ischaemic period and 30 min of reperfusion. The effects on physiology, purine metabolism and anaerobic glycolysis were compared with a control group subjected to the main ischaemia only. The brief ischaemic episodes did not produce stunning based on the recovery of left ventricular developed pressure (LVDP) and heart rate (HR) product during the first reperfusion. Preconditioning of 11–14% increased recovery of LVDP x HR during the second reperfusion was observed in the 1- and 4-min group. In the 2-min group a low repayment of flow debt during the first reperfusion was associated with a slightly reduced recovery of LVDP x HR compared to the other preconditioned groups during the second reperfusion. Only in the 4-min group was preconditioning associated with fewer breakdown products of the purine nucleotide pool (adenosine) and anaerobic glycolysis (lactate) in both tissue and effluate after the main ischaemia. Preconditioning (reflected in recovery of function) could be produced with ischaemic episodes of less than 5 min that did not produce stunning. Thus, stunning is probably not the primary cause of preconditioning.     

Iron supplement in pregnancy and development of gestational diabetes—a randomised placebo-controlled trial

Objective  To test the hypothesis that iron supplement from early pregnancy would increase the risk of gestational diabetes mellitus (GDM).
Design  Randomised placebo-controlled trial.
Setting  A university teaching hospital in Hong Kong.
Population  One thousand one hundred sixty-four women with singleton pregnancy at less than 16 weeks of gestation with haemoglobin (Hb) level between 8 and 14 g/dl and no pre-existing diabetes or haemoglobinopathies.
Methods  Women were randomly allocated to receive 60 mg of iron supplement daily ( n = 565) or placebo ( n = 599). Oral glucose tolerance tests (OGTTs) were performed at 28 and 36 weeks. Women were followed up until delivery.
Outcome measures  The primary outcome was development of GDM at 28 weeks. The secondary outcomes were 2-hour post-OGTT glucose levels, development of GDM at 36 weeks and delivery and infant outcomes.
Results  There was no significant difference in the incidence of GDM in the iron supplement and placebo groups at 28 weeks (OR: 1.04, 95% confidence interval [CI]: 0.7–1.53 at 90% power) or 36 weeks. Maternal Hb and ferritin levels were higher in the iron supplement group at delivery ( P < 0.001 and P = 0.003, respectively). Elective caesarean section rate was lower in the iron supplement group (OR: 0.58, 95% CI: 0.37–0.89). Infant birthweight was heavier ( P = 0.001), and there were fewer small-for-gestational-age babies in the iron supplement group (OR: 0.46, 95% CI: 0.24–0.85).
Conclusion  Iron supplement from early pregnancy does not increase the risk of GDM. It may have benefits in terms of pregnancy outcomes.     

Interactions between chromatic- and luminance-contrast-sensitive stereopsis mechanisms

It is well known that chromatic information can assist in solving the stereo correspondence problem. It has also been suggested that there are two independent first-order stereopsis mechanisms, one sensitive to chromatic contrast and the other sensitive to luminance contrast (Vision Research 37 (1997) 1271). Could the effect of chromatic information on stereo correspondence be subserved by interactions between these mechanisms? To address this question, disparity thresholds (1/stereoacuity) were measured using 0.5 cpd Gabor patches. The stimuli possessed different relative amounts of chromatic and luminance contrast which could be correlated or anti-correlated between the eyes. Stereoscopic performance with these compound stimuli was compared to that with purely isoluminant and isochromatic stimuli at different contrasts. It was found that anti-correlated chromatic contrast severely disrupted stereopsis with achromatic stimuli and that anti-correlated luminance contrast severely disrupted stereopsis with chromatic stimuli. Less dramatic, but still significant, was the improvement in stereoacuity obtained using correlated colour and luminance contrast. These data are consistent with there being positive and negative interactions between chromatic and achromatic stereopsis mechanisms that take place after the initial encoding of disparity information, but before the extraction of stereoscopic depth. These interactions can be modelled satisfactorily assuming probability summation of depth sign information between independent mechanisms.     

Texture-orientation mechanisms pool colour and luminance contrast

Do texture-sensitive mechanisms operate separately on, or pool, luminance and colour contrast information? We addressed this question by measuring threshold-versus-amplitude functions for orientation-modulated (OM) gratings comprised of gabor elements defined by either colour or luminance contrast. In both the uncrossed (all elements in test and mask defined by either colour or luminance contrast) and crossed (equal mixtures of luminance and colour contrast in both test and mask) conditions, evidence of sub-threshold facilitation between test and mask was obtained. The sub-threshold facilitation in the crossed condition could not be accounted for by luminance artifacts in the ostensibly isoluminant gabors. The results are consistent with a single visual mechanism sensitive to OM textures that pools information from both the luminance and chromatic post-receptoral mechanisms.     

Hypoxia favours necrotic versus apoptotic shedding of placental syncytiotrophoblast into the maternal circulation

In the third trimester of normal pregnancy, the mother tolerates daily shedding of several grams of dying placental trophoblast into the maternal circulation. The balance between apoptotic and necrotic shedding is presently unknown. Since pre-eclampsia is characterized by an altered placental oxygenation and increased trophoblast shedding, we investigated the role of oxygen on the balance of apoptotic versus necrotic trophoblast shedding in vitro.We studied human trophoblast turnover in explanted villi from late first and third trimester placentas in low oxygen (2 per cent) and higher oxygen tensions (6 per cent and 18 per cent) for up to 72h. Trophoblast turnover including apoptosis and necrosis were assessed by histology, immunolocalization of Mib-1 (proliferation marker), Bcl-2 (apoptosis inhibitor), activated caspase 3 (apoptosis promoter), cytokeratin 18 neo-epitope formation (M30 antibody), TUNEL test (DNA degradation), and (3)H-cytidine and(3) H-uridine incorporations.Culture in 2 per cent oxygen increased cytotrophoblast proliferation and syncytiotrophoblast shedding by necrosis. The proteins necessary for execution of apoptosis were mostly retained in the cytotrophoblast due to lack of syncytial fusion. Culture in 6 per cent and 18 per cent oxygen reduced cytotrophoblast proliferation. Syncytial fusion occurred and activity of caspase 3 was found in the syncytiotrophoblast; the latter remained intact demonstrating physiologic turnover, including apoptotic shedding.We conclude that severe placental hypoxia favours necrotic rather than apoptotic shedding of syncytial fragments into the maternal circulation. Since uteroplacental ischaemia is a significant risk factor for pre-eclampsia, these findings may explain the link between reduced uteroplacental blood flow and the systemic clinical manifestations of this disease.