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In this study we investigate the upgoing electron beams at the topside ionosphere and their counterpart feature, the bidirectional quasi-parallel electron beams (QPEB) in the equatorial magnetosphere, with highlight on their potential application in estimating the location of the arc's root (AR) in the magnetotail central plasma sheet (CPS). We infer from FAST data that the upgoing electron beam is often found in the equatorward vicinity of the inverted-V arc. On the premise of such a scenario, we propose a method to estimate the location of the AR from available magnetospheric measurements by assuming that the tailward boundary of the QPEB demarcates the earthward boundary of the AR. We report two events with THEMIS observations of QPEBs in the magnetotail CPS, and demonstrate how to use the QPEB features, together with the magnetic signatures of the current circuit constituted by the QPEB and arc, to estimate the earthward boundary of the AR. We find that the estimated earthward boundary of AR is situated at the periphery of a quasi-dipolar magnetosphere characterized by a strong Bz gradient. This finding is consistent with previously existing proposals on the possible AR location in the tail (e.g., Lui and Burrows, 1978; Sergeev et al., 2012).

Changes in diet type and nutrient availability can impose significant environmental stress on organisms, potentially compromising physiological functions and reproductive success. In nature, dramatic fluctuations in dietary resources are often observed and adjustments to restore cellular homeostasis are crucial to survive this type of stress. In this study, we exposed male Drosophila melanogaster to two modulated dietary treatments: one without a fasting period before exposure to a high-fat diet and the other with a 24-h fasting period. We then investigated mitochondrial metabolism and molecular responses to these treatments. Exposure to a high-fat diet without a preceding fasting period resulted in disrupted mitochondrial respiration, notably at the level of complex I. On the other hand, a short fasting period before the high-fat diet maintained mitochondrial respiration. Generally, transcript abundance of genes associated with mitophagy, heat-shock proteins, mitochondrial biogenesis, and nutrient sensing pathways increased either slightly or significantly following a fasting period and remained stable when flies were subsequently put on a high-fat diet, whereas a drastic decrease of almost all transcript abundances was observed for all these pathways when flies were exposed directly to a high-fat diet. Moreover, mitochondrial enzymatic activities showed less variation after the fasting period than the treatment without a fasting period. Overall, our study sheds light on the mechanistic protective effects of fasting prior to a high-fat diet and highlights the metabolic flexibility of Drosophila mitochondria in response to abrupt dietary changes and have implication for adaptation of species to their changing environment., (© 2024 The Authors. Insect Science published by John Wiley & Sons Australia, Ltd on behalf of Institute of Zoology, Chinese Academy of Sciences.)

Objective: This study assessed the quality of campus alcohol policies against best practice to assist campus decision-makers in strengthening their campus alcohol policies and reducing student alcohol use and harm., Methods: Drawing on empirical literature and expert opinion, we developed an evidence-based scoring rubric to assess the quality of campus alcohol policies across 10 alcohol policy domains. Campus alcohol policy data were collected from 12 Atlantic Canadian universities. All extracted data were verified by the institutions and then scored., Results: On average, post-secondary institutions are implementing only a third of the evidence-based alcohol policies captured by the 10 domains assessed. The average campus policy score was 33% (range 15‒49%). Of the 10 domains examined, only enforcement achieved an average score above 50%, followed closely by leadership and surveillance at 48%. The two heaviest-weighted domains-availability and access, and advertising and sponsorship-had average scores of 27% and 24%, respectively. However, if post-secondary campuses adopted the highest scoring policies from across all 12 campuses, they could achieve a score of 74%, indicating improvement is possible., Conclusion: Atlantic Canadian universities are collectively achieving less than half their potential to reduce student alcohol-related harm. However, this study identifies opportunities where policies can be enhanced or modified. The fact that most policies are present at one or more campuses highlights that policy recommendations are an achievable goal for campuses. Campuses are encouraged to look to each other as models for improving their own policies., (© 2024. The Author(s).)

The ionization of bioactive molecules impacts many ADME-relevant physicochemical properties, in particular, solubility, lipophilicity, and permeability. Ampholytes contain both acidic and basic groups and are distinguished as ordinary ampholytes and zwitterions. An influential review states that zwitterions only exist if the acidic p K a is significantly lower than the basic p K a . Through concordance of measured and calculated p K a and log P , we show that the zwitterionic behavior of several marketed drugs and natural products occurs despite a low or negative Δp K a . These nonclassical zwitterions are characterized by a weak acidic and basic p K a and conjugation through an extended aromatic system, often including pseudorings via intramolecular hydrogen bonds. In contrast to most classical zwitterions, nonclassical zwitterions can exhibit excellent permeability. As permeability and lipophilicity are typically correlated, the combination of low lipophilicity and high permeability makes nonclassical zwitterions an attractive design principle in medicinal chemistry.

Competing Interests: Intérêts concurrents:: Matt Bowes, Robert Strang et Dirk Huyer participent à la collaboration dans leur province entre les systèmes d’investigations médicolégales et de santé publique. Aucun autre intérêt concurrent n’a été déclaré.

The Werner syndrome RecQ helicase WRN was identified as a synthetic lethal target in cancer cells with microsatellite instability (MSI) by several genetic screens 1-6 . Despite advances in treatment with immune checkpoint inhibitors 7-10 , there is an unmet need in the treatment of MSI cancers 11-14 . Here we report the structural, biochemical, cellular and pharmacological characterization of the clinical-stage WRN helicase inhibitor HRO761, which was identified through an innovative hit-finding and lead-optimization strategy. HRO761 is a potent, selective, allosteric WRN inhibitor that binds at the interface of the D1 and D2 helicase domains, locking WRN in an inactive conformation. Pharmacological inhibition by HRO761 recapitulated the phenotype observed by WRN genetic suppression, leading to DNA damage and inhibition of tumour cell growth selectively in MSI cells in a p53-independent manner. Moreover, HRO761 led to WRN degradation in MSI cells but not in microsatellite-stable cells. Oral treatment with HRO761 resulted in dose-dependent in vivo DNA damage induction and tumour growth inhibition in MSI cell- and patient-derived xenograft models. These findings represent preclinical pharmacological validation of WRN as a therapeutic target in MSI cancers. A clinical trial with HRO761 (NCT05838768) is ongoing to assess the safety, tolerability and preliminary anti-tumour activity in patients with MSI colorectal cancer and other MSI solid tumours., (© 2024. The Author(s).)

Competing Interests: Competing interests:: Matt Bowes, Robert Strang, and Dirk Huyer are involved in the collaboration in their province between death investigation and public health systems. No other competing interests were declared.

The Werner Syndrome RecQ helicase (WRN) is a synthetic lethal target of interest for the treatment of cancers with microsatellite instability (MSI). Different hit finding approaches were initially tested. The identification of WRN inhibitors proved challenging due to a high propensity for artefacts via protein interference, i. e., hits inhibiting WRN enzymatic activities through multiple, unspecific mechanisms. Previously published WRN Helicase inhibitors (ML216, NSC19630 or NSC617145) were characterized in an extensive set of biochemical and biophysical assays and could be ruled out as specific WRN helicase probes. More innovative screening strategies need to be developed for successful drug discovery of non-covalent WRN helicase inhibitors., (© 2024 Wiley‐VCH GmbH.)

Health care providers (HCPs) are entrusted with providing credible health-related information to their patients/clients. Patients/clients who receive physical activity and exercise (PAE) advice from an HCP typically increase their PAE level. However, most HCPs infrequently discuss PAE or prescribe PAE, due to the many challenges (e.g., time, low confidence) they face during regular patient care. The purpose of this study was to ascertain HCPs' perspectives of what could be done to promote PAE in health care. HCPs ( n = 341) across Nova Scotia completed an online self-reflection survey regarding their current PAE practices and ideas to promote PAE. The sample consisted of 114 physicians, 114 exercise professionals, 65 dietitians, and 48 nurses. Quantitative textual analysis (frequency of theme ÷ number of respondents) was performed to identify common themes to promote PAE in health care. In the pooled sample, the primary theme cited was to increase the availability of community programs (24.1% of respondents), followed by more educational opportunities for providers (22.5%), greater promotion of PAE from HCPs (17.1%), reducing financial barriers experienced by patients/clients (16.3%), and increasing availability of qualified exercise professionals (15.0%). Altogether, increased PAE education and greater availability of affordable community PAE programs incorporating qualified exercise professionals, would reduce barriers preventing routine PAE promotion and support the promotion of PAE in Nova Scotia.

Metabolic inflexibility is a condition that occurs following a nutritional stress which causes blunted fuel switching at the mitochondrial level in response to hormonal and cellular signalling. Linked to obesity and obesity related disorders, chronic exposure to a high-fat diet (HFD) in animal models has been extensively used to induce metabolic inflexibility and investigate the development of various metabolic diseases. However, many questions concerning the systemic and mitochondrial responses to metabolic inflexibility remain. In this study, we investigated the global and mitochondrial variations following a 10-day exposure to a HFD in adult Drosophila melanogaster. Our results show that following 10-day exposure to the HFD, mitochondrial respiration rates measured in isolated mitochondria at the level of complex I were decreased. This was associated with increased contributions of non-classical providers of electrons to the electron transport system (ETS) such as the proline dehydrogenase (ProDH) and the mitochondrial glycerol-3-phosphate dehydrogenase (mtG3PDH) alleviating complex I dysfunctions, as well as with increased ROS production per molecule of oxygen consumed. Our results also show an accumulation of metabolites from multiple different metabolic pathways in whole adult Drosophila and a drastic shift in the lipid profile which translated into decreased proportion of saturated and monounsaturated fatty acids combined with an increased proportion of polyunsaturated fatty acids. Thus, our results demonstrate the various responses to the HFD treatment in adult Drosophila melanogaster that are hallmarks of the development of metabolic inflexibility and reinforce this organism as a suitable model for the study of metabolic disorders., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Retinoic acid receptor-related orphan receptor gamma-t (RORγt) is considered to be the master transcription factor for the development of Th17 cells that produce proinflammatory cytokines such as IL-17A. Overproportionate Th17 cell abundance is associated with the pathogenesis of many inflammatory conditions including psoriasis. In a high-throughput fluorescence resonance energy transfer (FRET) screen, we identified compound 1 as a hit with promising lipophilic efficiency (LipE). Using structure-based drug design based on a number of X-ray cocrystal structures, we morphed this hit class into potent imidazoles, exemplified by compound 3 . To improve the poor absorption, distribution, metabolism, and excretion (ADME) properties of neutral imidazoles, we extended our ligands with carboxylic acid substituents toward a polar, water-rich area of the protein. This highly lipophilicity-efficient modification ultimately led to the discovery of compound 14 , a potent and selective inhibitor of RORγt with good ADME properties and excellent in vivo pharmacokinetics. This compound showed good efficacy in an in vivo delayed-type hypersensitivity pharmacology model in rats.

Competing Interests: Competing interests: None declared.

Design and optimization of benzo- and pyrido-thiazoles/isothiazoles are reported leading to the discovery of the potent, orally bioavailable Syk inhibitor 5, which was found to be active in a rat PK/PD model. Compound 5 showed acceptable overall kinase selectivity. However, in addition to Syk it also inhibited Aurora kinase in enzymatic and cellular settings leading to findings in the micronucleus assay. As a consequence, compound 5 was not further pursued., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Overhead athletes often suffer injury to the glenohumeral joint secondary to inherent instability. However, little is known about the relationship between core stability and shoulder dysfunction among athletes., Purpose: The purpose of this study was to analyze the difference between healthy athletes and those with shoulder dysfunction in regard to core stability measures. Secondary purpose was to explore the relationship between measures of core stability and measures of shoulder dysfunction., Methods: Participants consisted of NCAA Division III overhead athletes (28 males, 33 females) with a mean age of 19.3 ± (1.1) years, mean weight of 173.6 ± (36.9) pounds, mean height of 67.8 ± (3.5) inches. Functional questionnaires (the Kerlan-Jobe Orthopaedic Clinical Scale [KJOC] and the QuickDASH sports module) as well as Single-Leg Stance Balance Test (SLBT), Double Straight Leg Lowering Test (DLL), Sorensen Test, and Modified Side Plank Test were completed in a randomized order with consistent raters., Results: MANOVA was significant at (p = .038) for the comparison between the experimental group and the control group for the values of Right SLBT. The experimental group had significantly less balance than the control group with means of 10.14 ± (5.76) seconds and 18.98 ± (15.22) seconds respectively. Additionally, a positive correlation was found between the DLL and the KJOC at (r = .394, p > .05) and a negative correlation was found between the Right SLBT and the Quick DASH sports module (QD) at (r = -.271, p > .05)., Discussion and Conclusion: Balance deficiency was found in athletes with shoulder dysfunction. According to this study, greater shoulder dysfunction is correlated with greater balance and stability deficiency. Therapists and trainers should consider incorporating balance training as an integral component of core stability into rehabilitation of athletes with shoulder dysfunction., Level of Evidence: 3b.

Objectives: Canada's progress in establishing a national immunization registry and coordinated immunization schedule across provinces has been slow. The absence of a centralized registry means there are only limited data available on childhood immunization coverage in Canada. The aim of this study was to estimate the completeness and timeliness of immunization for two year-old children in Nova Scotia., Methods: The study included 8,245 babies born in Nova Scotia during 2006. Immunization data were derived from three sources: Provincial Medical Insurance Physician Billing data, public health records, and self-report by parents. Immunization uptake rates for vaccines included in the Nova Scotia immunization schedule were calculated at ages 12, 18 and 24 months. Logistic regression was used to analyze vaccine uptake in relation to socio-economic factors. A telephone survey of a sample of parents of study children was completed., Results: The overall immunization completeness rate was 49% at 12 months, 40% at 18 months and 58% at 24 months of age. Immunization completeness was significantly higher in more socially disadvantaged communities., Conclusions: Nova Scotia spends many millions of dollars on vaccine purchase and administration, but, as with numerous Canadian jurisdictions, there is no accurate system for monitoring or evaluating the program. The timeliness and completeness of immunization administration to pre-school children in Nova Scotia is inadequate. Further work should elucidate the barriers and enablers to immunization to ensure that public health education targets those most likely to be under-immunized. A provincial vaccination database should be established to monitor and evaluate the system.

Hypertension is the leading risk for premature death in the world. High dietary sodium is an important contributor to increased blood pressure and is strongly associated with other important diseases (e.g., gastric cancer, calcium containing kidney stones, osteoporosis, asthma and obesity). The average dietary sodium intake in Canada is approximately 3400 mg/day. It is estimated that 30% of hypertension, more than 10% of cardiovascular events and 1.4 billion dollars/year in health care expenses are caused by this high level of intake in Canada. Since 2006, Canada has had a focused and evolving effort to reduce dietary sodium based on actions from Non Governmental Organizations (NGO), and Federal and Provincial/Territorial Government actions. NGOs initiated Canadian sodium reduction programs by developing a policy statement outlining the health issue and calling for governmental, NGO and industry action, developing and disseminating an extensive health care professional education program including resources for patient education, developing a public awareness campaign through extensive media releases and publications in the lay press. The Federal Government responded by striking a Intersectoral Sodium Work Group to develop recommendations on how to implement Canada's dietary reference intake values for dietary sodium and by developing timelines and targets for foods to be reduced in sodium, assessing key research gaps with funding for targeted dietary sodium based research, developing plans for public education and for conducting evaluation of the program to reduce dietary sodium. While food regulation is a Federal Government responsibility Provincial and Territorial governments indicated reducing dietary sodium needed to be a priority. Federal and Provincial Ministers of Health have endorsed a target to reduce the average consumption of sodium to 2300 mg/day by 2016 and the Deputy Ministers of Health have tasked a joint committee to review the recommendations of the Sodium Work Group and report back to them.

Key members (a.k.a. "champions") within specific work units were provided with a brief training session designed to increase awareness of the benefits associated with influenza vaccination. The champions were responsible for encouraging members of their work units to accept an influenza vaccination and in some cases had the requisite training to administer the vaccination on site. Work units were randomly assigned to either champion present or champion absent conditions. Results show increased vaccination compliance for groups where a champion was present (N = 23). An independent sample t-test revealed a significant difference between the two groups t = 2.30, p < .03 which resulted in a percentage change from 41% in the unchampioned group to 52% in the championed group. Analyses which included only those units that had a fully trained champion (N = 13) produced a similar percentage increase in vaccine uptake from 41% to 54% (although this did not reach statistical significance; p = .08). Overall, the presence of a unit champion did produce a clinically relevant increase in vaccination rates in championed work units. This result has implications for future vaccination campaigns in hospital settings. Future research targeting the barriers and drivers of influenza vaccination among HCWs is recommended.

Background: Chlamydia is the most prevalent sexually transmissible infection (STI) in Canadian adolescents. STI account for 20% of cases of infertility in Canada and 42% of ectopic pregnancies are attributable to previous chlamydia infection. Despite the importance of this infection, little is understood about young people's knowledge of it., Methods: A survey was conducted at a rural high school in Nova Scotia, Canada, to assess students' knowledge of chlamydia and associations of knowledge with gender and protective behaviours. Knowledge was assessed using true-false responses to 15 statements about chlamydia. Each statement was examined for differences in the percentage of correct responses by sex. Correct responses were summed, creating a knowledge score. Socioeconomic status variables and age were included in multivariate regression models to determine if they modified associations between knowledge score and protective behaviours seen in simple regression., Results: Eighty-six percent of registered students (n = 538) participated in the survey. Girls responded to 10 of the 15 knowledge statements significantly more often than boys. Respondents were least knowledgeable about their rights to confidential health services for chlamydia infection. Knowledge score was associated with use of both condoms and oral contraception at last intercourse in girls (odds ratio 1.15; 95% confidence interval 1.01-1.31). No association of knowledge score was seen with having had an STI test in the previous year., Conclusions: School sexual health programs should make special efforts to meet the needs of male students, and programs and health professionals should include information about the confidential nature of sexual health services for adolescents.

Objective: The effective decontamination of reusable dental instruments is essential to reduce the risks from onward transmission of infectious diseases. There are therefore a number of legislative requirements placed upon manufacturers of medical devices (which includes dental instruments) to provide validated methods for the reprocessing of such devices. The aim of this study was to determine the availability and content of manufacturer's instructions for the reprocessing of reusable dental instruments., Materials and Methods: A database of reusable dental instruments with details of their manufacturers was collated from information received from three dental hospitals. A questionnaire was sent to all the manufacturers requesting information about the reprocessing instructions for their products. The response from each manufacturer was assessed for the quality of the information and compliance with the British, European and International Standard, BS EN ISO 17664 (2004)., Results: The database from the three dental hospitals included over 800 items supplied by 54 different manufacturers/suppliers. Forty protocols were available for assessing compliance with BS EN ISO 17664 (2004). These protocols accounted for 25 (46%) manufacturers covering 300 devices. The majority (90%) of the returned questionnaires did not comply with the required standard and provided insufficient information to allow for the effective decontamination of the instruments., Conclusions: Manufacturers of medical devices are legally required to supply the user with validated instructions to enable effective decontamination of these devices. The information must be in a format as specified in BS EN ISO 17664 (2004). The information obtained in this survey demonstrated that the manufacturers' instructions fall short of the required regulatory requirements. The absence of such instructions increases the risk of cross-infection arising from inadequate cleaning, decontamination and sterilisation.

Objectives: A self-test screening program for genital C. trachomatis infection in female students attending high school in rural Nova Scotia was introduced. The objectives of this pilot study were to determine the extent of uptake, reasons for being/not being screened, and whether students at risk would be more likely to be screened., Methods: The screening program was carried out between September 2005 and May 2006. Test kits were accessed through the school's health centre without first seeing the school nurse for counselling. Tests were processed non-nominally at the laboratory. A cross-sectional survey was offered to all students in the school to assess factors related to participation or non-participation. Univariate analysis was carried out for young women's sexual activity and risk taking, reasons for being participants or non-participants, risk behaviours, and knowledge about chlamydia., Results: One hundred and sixty-three women (58%) had had vaginal intercourse at least once. Twenty-four of these used the self-test kit. Though 83% of those not using the self-test knew that females with chlamydia are very often asymptomatic, 54% indicated lack of symptoms as a reason for not doing so. Many (49%) gave low probability of infection as a reason for not using the kit, but high-risk sexual activity was frequent in these young, Discussion: Uptake of self-testing for C. trachomatis was lower than anticipated. This may be due to lack of counselling meant to encourage testing to overcome a dissonance of knowledge and behaviour. Self-testing should be further explored to better understand its potential to increase chlamydia screening among Canadian adolescents.

The purpose of this study was to determine whether direct nursing care providers have decisional conflict about receiving influenza vaccinations and characteristics associated with decisional conflict. The researchers used a self-administered questionnaire mailed to direct nursing care providers in two long-term-care organizations. Most direct nursing care providers in both organizations (80% and 93%, respectively) intended to get the influenza vaccine. Unregulated direct nursing care providers had more decisional conflict than regulated providers, especially related to feeling uninformed about the pros and cons of influenza vaccination. Unclear valuing of the pros and cons of influenza vaccination was related to the age of the direct care providers in both organizations. Decisional conflict and influenza vaccination practices may be determined, in part, by age and by the culture of a health care organization. A decision aid to improve knowledge and clarify values may improve decision quality and increase influenza vaccination rates.

Objective: To report the use of spectroscopic analysis of dental fluorescence excited with a blue InGaN laser diode operating at 405 nm., Method: The spectra resulting from three classifications of smooth surface non-cavitated caries lesions (dull, shiny, brown) with 20 samples in each group were examined using the ratio of integrated fluorescence intensity in two spectral bands., Results: All lesions demonstrated spectra which were significantly different from sound tooth structure. As expected, the 'brown' lesions demonstrated a significantly different spectral profile from the two white spot lesion classifications. Dull and shiny lesions had significantly different spectral measurements when examining the ratio of the integrated fluorescence in spectral bands between 480-500 and 620-640 nm., Conclusion: This method has application for detection of dental caries as well as demonstrating potential application to evaluate lesions which may represent different degrees of caries activity.

This study aimed to determine the contribution of the underlying dentine and the enamel-dentine junction to measurements of mineral loss from enamel recorded using quantitative light fluorescence (QLF). Sixteen square blocks (5 x 5 mm) were cut from the labial surfaces of extracted bovine incisor teeth. A dental drill was used to remove dentine and the enamel-dentine junction from half of each specimen. All specimens were embedded in epoxy resin and ground to produce a smooth, flat enamel surface. Half of the enamel surface of the block, perpendicular to where the dentine had been removed, was demineralised for 72 h prior to undertaking QLF measurements from the enamel surface to compare fluorescence loss from different areas of the block. QLF readings taken from lesions with no underlying dentine or enamel-dentine junction were very similar to readings from lesions with underlying dentine. A comparison of the two data sets demonstrated a linear relationship with a gradient of 0.95 and a y intercept of -1.24 (r(2) = 0.936). From these data, the underlying dentine and enamel-dentine junction did not influence mineral loss in enamel measured using QLF., (Copyright 2002 S. Karger AG, Basel)

Evidence is accumulating that gastrin precursors may act as growth factors for the colonic mucosa in vivo. The aims of this study were to prepare recombinant human progastrin(6-80) and to investigate its structure and biological activities in vitro. Human progastrin(6-80) was expressed in Escherichia coli as a glutathione S-transferase fusion protein. After thrombin cleavage progastrin(6-80) was purified by reverse phase high pressure liquid chromatography and characterized by radioimmunoassay, amino acid sequencing, and mass spectrometry. Assays for metal ions by atomic emission spectroscopy revealed the presence of a single tightly bound calcium ion. Progastrin(6-80) at concentrations in the pm to nm range stimulated proliferation of the conditionally transformed mouse colon cell line YAMC. The observations that progastrin(6-80) did not bind to either the cholecystokinin (CCK)-A or the gastrin/CCK-B receptor expressed in COS cells and that antagonists selective for either receptor did not reverse the proliferative effects of progastrin(6-80) suggested that progastrin(6-80) stimulated proliferation independently of either the CCK-A or the gastrin/CCK-B receptor. We conclude that recombinant human progastrin(6-80) is biologically active and contains a single calcium ion. With the exception of the well known zinc-dependent polymerization of insulin and proinsulin, this is the first report of selective, high affinity binding of metal ions to a prohormone.

Objectives: To investigate the effect of four variables: wavelength (633 nm and 780 nm), bandwidth filter (3 kHz, 15 kHz, 22 kHz), probe fibre separation (250 microns) and 500 microns) and distance of the probe from the gingival margin (2-3 mm and 4-5 mm) when assessing the vitality of anterior teeth with a laser Doppler flowmetry system., Design: Split-mouth cohort clinical trial., Setting: Childrens dental clinic, Glasgow Dental Hospital and School., Sample and Methods: Sample included 11 non-vital maxillary incisors with necrotic pulps in 10 patients (mean age 12.25 years old). Recordings were taken from the non-vital tooth and from a vital maxillary incisor from the same patient, using all 24 combinations of the recording variables listed above. The vital/non-vital ratios of the signals from the 11 pairs of teeth were calculated and discriminant analysis applied to the data., Results: Of the variables investigated, the combination of a 633 nm laser source with a 3 kHz bandwidth filter using a probe with a 500 microns fibre separation placed 2-3 mm from the gingival margin was the most reliable, with 10 out of a possible 11 true positives for pulpal necrosis, no false positives, and one equivocal diagnosis, and was the only combination that recorded a smaller blood flow from the non-vital tooth compared with the vital control tooth for all 11 pairs of teeth investigated., Conclusions: It was concluded, therefore, that laser Doppler flowmetry can be of use in assessing the vitality of anterior teeth and that this is the preferred combination of recording variables for further investigations.

Background and Objective: A novel pulsed CO(2) laser was examined for its ability to ablate hard dental tissues., Study Design/materials and Methods: Lased human enamel surfaces were viewed using light and scanning electron microscopy for evidence of adverse structural changes. In vitro shear bond strength tests were conducted on composite resin bonded to lased enamel surfaces and compared with conventionally prepared specimens. A thermal camera was used to monitor temperature changes during cavity preparation in tooth slabs to assess likely changes to the dental pulp., Results: No charring or surface cracks were observed on lased enamel surfaces using both microscopic techniques. Bonding of the lased enamel surfaces to composite resin was not significantly different from the acid-etched control group. For cavities with a remaining dentine thickness of less than 1 mm, the temperature rise was less than 6 degrees C., Conclusion: A novel pulsed CO(2) laser shows promise for cutting cavities in teeth., (Copyright 2000 Wiley-Liss, Inc.)

Laser Doppler flowmetry is a non-invasive electrooptical technique which allows the semi-quantitative recording of pulpal blood flow. This study aimed to determine the reliability (measured as the sensitivity and specificity) of laser Doppler flowmetry as a method of assessing the vitality of traumatised anterior teeth, and to compare it with standard pulpal diagnostic tests. Recordings of pulpal blood flow were taken from 67 non-vital anterior teeth (55 patients), where the pulpal status was confirmed by pulpectomy. For comparison, recordings were also taken from 84 vital anterior teeth (84 patients). Analysis of the recordings allowed diagnostic criteria to be developed which gave the technique a sensitivity and specificity of 1.0 for this sample. None of the other standard pulpal diagnostic methods tested was as reliable. This was usually due to low sensitivities, which ranged between 0.92 for sensibility testing with ethyl chloride down to 0.36 for periapical radiolucency and 0.16 for a history of pain. Laser Doppler flowmetry was found to be a reliable method of assessing the pulpal status of traumatised anterior teeth, although it is technique-sensitive and time-consuming to use.

This review of the published literature on dental materials for the year 1997 has been compiled by the Dental Materials Panel of UK. It continues a series of annual reviews started in 1973. Emphasis has been placed upon publications, which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, ceramometallic restorations and resin-bonded bridges, ceramics, denture base resins and soft lining materials, impression materials, dental implant materials, orthodontic materials, biomechanics and image processing, resin composites, and casting investment materials and waxes). Three hundred and thirty three articles have been reviewed.

The present study aims to assess the ability of saliva, both in vitro and in situ, to prevent surface mineral loss from enamel and dentine when exposed to an erosive challenge. Fifteen groups of four varnished thin tooth sections were stored in saliva collected from individuals taking part in the in situ study and a further eight groups, each containing four sections, were stored in deionised water. In vitro, sections were stored in saliva or water for 14 days. In addition, fifteen subjects each wore an appliance with four varnished sections. Appliances with sections were worn for 14 days. All sections were exposed to 25 ml of erosion solution for 5 min twice daily. Microradiography and image analysis of the recovered sections demonstrated significant protection of surface mineral loss from enamel and dentine by saliva in vitro and in situ compared with deionised water (p < 0.05). Significantly less mineral loss (p < 0.05) was observed for enamel and dentine stored in situ compared with storage in saliva in vitro. Generalised linear modelling demonstrated both the subject and protocol had significant effect on mineral loss. A weak positive correlation (r = 0.64) was noted when in situ and in vitro mineral loss from enamel were compared, demonstrating greater reactivity of the in vitro enamel specimens to the erosion challenge. The dentine data did not show any linear correlation. Saliva protected against mineral loss by erosion and, for enamel, in vitro results demonstrated a weak positive correlation with in situ results.

This critical review of the published literature on dental materials for the year 1996 has been compiled by the Dental Materials Panel of the UK. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, resin-bonded bridges and ceramo-metallic restorations, ceramics, denture base resins and soft lining materials, impression materials, implants materials, orthodontic materials, biomechanics and image processing, resin composites and casting investment materials and waxes). Three hundred and thirteen articles have been reviewed.

This paper describes a novel application of transverse microradiography for the detection and quantification of mineral loss due to acid erosion in thin tooth sections. Sixty-four specimens were randomly divided into eight equal-sized groups and exposed to an orthophosphoric-acid-based erosive fluid (pH = 3) for 0, 0.25, 0.5, 1, 2, 5, 12, or 24 hrs. We made microdensitometric scans separately across both enamel and dentin to derive data for the total mineral loss and the minimum mineral content within the eroded area. We then analyzed specimens using a profilometer to determine (1) the area above a plot of penetration depth against distance and (2) the maximum depth of penetration. Correlation coefficients for comparisons between microradiographic and profilometric data for both enamel and dentin specimens varied between 0.87 and 0.96. Two-sample t tests demonstrated that the microradiographic technique could detect early erosion, i.e., discriminate between erosion times of less than 1 hr. It was concluded that this application of transverse microradiography was a useful and acceptable method for the measurement of early mineral loss in vitro, occurring as a result of acid erosion.

Plaque pH was measured using a glass combination pH microelectrode of plaque deposits lining the trough of an intra-oral appliance which contained single sections of human teeth with artificial enamel lesions. Plaque exposure to a 10% sucrose solution produced significantly lower plaque pH levels than a solution of sorbitol gum extract. The subsequent flow of saliva over the plaque/pH electrode interface resulted in a significant and rapid increase in pH. Repeat experiments, using deionised water instead of saliva, demonstrated no increase in pH at the plaque/electrode interface. This system may provide a convenient method of producing plaque suitable for repeated pH analysis in intimate association with artificial enamel lesions. This may permit further study of the relationship between plaque acidogenicity, salivary buffering capacity and mineral change within the incipient enamel lesion.

A Neodymium-yttrium aluminium garnet (Nd-YAG) pulsed laser was used in vitro to determine whether various laser energy levels from 0.75 W to 1.7 W at 15 pulses s(-1) (pps) were able to (i) remove debris from the walls of prepared root canals (ii) remove pulpal tissue from unprepared canals and (iii) create a fused apical plug from dentine chips, hydroxyapatite (HAP) or low-fusing dental porcelain. Single-rooted teeth were sectioned at the amelocemental junction and the crowns discarded. The root canals of 50 teeth were prepared chemomechanically and allocated to four groups of 10 teeth for laser treatment. One group was left unlased as a control. After lasing, the teeth were split longitudinally, stained and examined for residual debris. Results showed that there was no statistically significant difference between the groups (P<0.05). A further 20 teeth were not prepared and lased in the coronal one-third of the root canal at different energy levels; five teeth were not lased. The teeth were split and examined as previously. The results showed that lasing cleaned the coronal part of the root canal almost completely of pulpal tissue. In the final part of the study laser energy was applied to dentine chips, HAP and low-fusing porcelain in an attempt to produce a fused apical plug. The laser was unable to melt the dentine chips but some hardening of HAP occurred when combined with blue food-colouring, with or without glycerine, at energy levels of 1.0 W, at 15 pps for 30 s. Superficial hardening of low-fusing porcelain occurred at 1.0 W, 15 pps for 30 s.

The pulsed Nd: YAG laser is advocated as an alternative means of providing analgesia during routine dental procedures. Since the evidence to support this claim is mainly anecdotal, a clinical trial was carried out using an electric pulp tester (EPT) to measure the extent and duration of any analgesic effect induced by pulsed Nd: YAG laser treatment. A double-blind crossover experiment involving laser and sham treatments was used on 21 subjects. A small (3.6 arbitrary units) but statistically significant increase was observed in the mean responses measured 5 min after laser treatment with 113 mJ pulses at 15 pulses s-1 (pps) for 3 min. The pain thresholds returned to baseline values after 60 min. No statistically significant changes in threshold were found with the sham treatment. The order in which laser and sham treatment was received made no difference to the results.

Two independent cross-over studies have now been carried out to evaluate the effect of a regime of chewing sucrose-containing gum on enamel lesion remineralization. The first study has been reported in detail elsewhere. This further study aimed to increase the data set with an additional 13 volunteers. Similar protocols were followed in both studies. Weighted averages from the two studies showed delta z values corresponding to 16.8% remineralization for the gum versus 11.6% remineralization for the control (p = 0.046, two-sided). A significant difference between test and control was evident for lesion body (p = 0.0004, two-sided) but not for surface zone (p = 0.32, two-sided).

The aims of this study were firstly to investigate the fluoride-releasing characteristics of five commercial glass ionomer materials: Ketac Fil, Chemfil Superior, Fuji II LC, Aquacem and Vitrebond. The second aim was to assess the fluoride uptake and subsequent release from the same range of materials. In both tests, ten discs, 6 mm in diameter with a thickness of 1.5 mm, were made for each material. The initial fluoride release was assessed over a 60-day period for all materials. Each disc was immersed in 2 ml of de-ionised water within a plastic vial. The solutions were changed daily up to day 15, and thereafter every 3 and 4 days until the end of the test. All of the materials released measurable amounts of fluoride throughout the test period, with a considerable range on day 1 (15.3-155.2 ppm F). The concentration of fluoride released on the 2nd day fell sharply for all materials (range 6.3-44.3 ppm F). By day 60 all materials continued to release fluoride, albeit to a lesser extent (range 0.9-3.99 ppm F). With regard to the uptake and release of fluoride, a similar protocol was employed, although all samples were immersed in 1 litre of de-ionised water for 60 days to allow the majority of the fluoride to leach out from the materials. The ten pellets for each material were divided into two groups, five samples as control and five samples as test. Each day over a 20-day period all test samples were exposed to a 1000-ppm F solution for 2 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization with the use of chewing gum. The first study involved a sorbitol-containing chewing gum, and the second, which had an identical protocol, tested a sucrose-containing chewing gum. In each study, 12 volunteers wore in situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice daily for two min with a 1100-ppm-F (NaF) dentifrice (control and test) and in the test phase chewed five sticks of gum per day for 20 min after meals and snacks. Microradiographs of the enamel lesions were made at baseline and at the end of the seven-week experimental period. In the sugar-free gum study, the weighted mean total mineral loss (delta z) difference [(wk7-wk0) x (-1)] was 788 vol.% min. x micron for the gum, corresponding to remineralization of 18.2%, vs. the control value of 526 vol.% min. x micron, 12.1% remineralization (p = 0.07). There were no significant differences for the surface-zone (p = 0.20) and lesion-body (p = 0.28) values. In the sucrose-containing gum study, the delta z difference was 743 vol.% min. x micron for the gum, corresponding to a remineralization of 18.3%, vs. the control value of 438 vol.% min. x micron, 10.8% remineralization (p = 0.08). The surface-zone values were not significantly different (p = 0.55). For the lesion body, however, the sucrose-containing gum value of 6.11 vol.% min. was significantly different (p = 0.01) from that of the control (2.81 vol.% min.).

This study investigated the marginal seal of resin composite inlays in dentin and enamel when either unfilled resin or a second or third generation dentin bonding agent is used. Standardized mesial and distal inlay cavities were cut in 135 human third molar teeth. The teeth were randomly divided into 9 groups and inlays fabricated in a hybrid resin composite inlay material. Each group of teeth was then treated with one of 8 dentin bonding agents or an unfilled resin and cemented with a dual curing resin cement. Each group was stored in deionized water for 1 week, thermocycled between 5 degrees C, 37 degrees C and 55 degrees C for 500 cycles, then placed in 2% methylene blue solution for 15 hours. Following this the teeth were sectioned and scored for the degree of leakage observed. Marginal microleakage was minimal at enamel margins, however there was marked leakage, even when a dentin bonding agent was used, on the dentin side. Only two dentin bonding agents proved more effective than unfilled resin and in only one case was the leakage not significantly worse than in enamel.

Composite inlays have been introduced to overcome some of the problems encountered with direct placement techniques. However, some doubt has been expressed about the strength of the bond between the inlay surface and the composite luting cement due to the decreased number of C = C bonds remaining following supercuring of the inlay. This study investigated the bond strength of three composite inlay systems to etched bovine enamel and recorded the plane of fracture of the samples. The bond strength of one system was significantly greater than that of the other groups and was increased by the application of an unfilled resin enamel bonding agent. Unfilled resin application did not significantly alter the other systems tested. In only one of the systems tested was the inlay/composite cement bond found to be the weak link in the bonding procedure. In this group, the application of the manufacturer's specially formulated bond enhancer did not lead to an increase in bond strength.