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Abstract Background Urine from male Sprague-Dawley rats 25, 40, and 80 days old was analyzed by NMR and UPLC/MS. The effects of data normalization procedures on principal component analysis (PCA) and quantitative analysis of NMR-based metabonomics data were investigated. Additionally, the effects of age on the metabolic profiles were examined by both NMR and UPLC/MS analyses. Results The data normalization factor was shown to have a great impact on the statistical and quantitative results indicating the need to carefully consider how to best normalize the data within a particular study and when comparing different studies. PCA applied to the data obtained from both NMR and UPLC/MS platforms reveals similar age-related differences. NMR indicated many metabolites associated with the Krebs cycle decrease while citrate and 2-oxoglutarate, also associated with the Krebs cycle, increase in older rats. Conclusion This study compared four different normalization methods for the NMR-based metabonomics spectra from an age-related study. It was shown that each method of normalization has a great effect on both the statistical and quantitative analyses. Each normalization method resulted in altered relative positions of significant PCA loadings for each sample spectra but it did not alter which chemical shifts had the highest loadings. The greater the normalization factor was related to age, the greater the separation between age groups was observed in subsequent PCA analyses. The normalization factor that showed the least age dependence was total NMR intensity, which was consistent with UPLC/MS data. Normalization by total intensity attempts to make corrections due to dietary and water intake of the individual animal, which is especially useful in metabonomics evaluations of urine. Additionally, metabonomics evaluations of age-related effects showed decreased concentrations of many Krebs cycle intermediates along with increased levels of oxidized antioxidants in urine of older rats, which is consistent with current theories on aging and its association with diminishing mitochondrial function and increasing levels of reactive oxygen species. Analysis of urine by both NMR and UPLC/MS provides a comprehensive and complementary means of examining metabolic events in aging rats.

Abstract Background Computerised cognitive behaviour therapy (cCBT) involves standardised, automated, interactive self-help programmes delivered via a computer. Randomised controlled trials (RCTs) and observational studies have shown than cCBT reduces depressive symptoms as much as face-to-face therapy and more than waiting lists or treatment as usual. cCBT’s efficacy and acceptability may be influenced by the “human” support offered as an adjunct to it, which can vary in duration and can be offered by people with different levels of training and expertise. Methods/design This is a two-by-two factorial RCT investigating the effectiveness, cost-effectiveness and acceptability of cCBT supplemented with 12 weekly phone support sessions are either brief (5–10 min) or extended (20–30 min) and are offered by either an expert clinician or an assistant with no clinical training. Adults with non-suicidal depression in primary care can self-refer into the study by completing and posting to the research team a standardised questionnaire. Following an assessment interview, eligible referrals have access to an 8-session cCBT programme called Beating the Blues and are randomised to one of four types of support: brief-assistant, extended-assistant, brief-clinician or extended-clinician. A sample size of 35 per group (total 140) is sufficient to detect a moderate effect size with 90% power on our primary outcome measure (Work and Social Adjustment Scale); assuming a 30% attrition rate, 200 patients will be randomised. Secondary outcome measures include the Beck Depression and Anxiety Inventories and the PHQ-9 and GAD-7. Data on clinical outcomes, treatment usage and patient experiences are collected in three ways: by post via self-report questionnaires at week 0 (randomisation) and at weeks 12 and 24 post-randomisation; electronically by the cCBT system every time patients log-in; by phone during assessments, support sessions and exit interviews. Discussion The study’s factorial design increases its efficiency by allowing the concurrent investigation of two types of adjunct support for cCBT with a single sample of participants. Difficulties in recruitment, uptake and retention of participants are anticipated because of the nature of the targeted clinical problem (depression impairs motivation) and of the studied interventions (lack of face-to-face contact because referrals, assessments, interventions and data collection are completed by phone, computer or post). Trial registration Current Controlled Trials ISRCTN98677176

Abstract Background Most people who stop smoking successfully for a few weeks will return to smoking again in the medium term. There are few effective interventions to prevent this relapse and none used routinely in clinical practice. A previous exploratory meta-analysis suggested that self-help booklets may be effective but requires confirmation. This trial aims to evaluate the effectiveness and cost-effectiveness of a set of self-help educational materials to prevent smoking relapse in the National Health Service (NHS) Stop Smoking Service. Methods/design This is an open, randomized controlled trial. The target population is carbon monoxide (CO) verified quitters at four weeks in the NHS stop smoking clinic (total sample size N = 1,400). The experimental intervention tested is a set of eight revised Forever Free booklets, including an introduction booklet and more extensive information on all important issues for relapse prevention. The control intervention is a leaflet that has no evidence to suggest it is effective but is currently given to some patients using NHS stop smoking services. Two follow-up telephone interviews will be conducted at three and 12 months after the quit date. The primary outcome will be prolonged abstinence from months four to 12 with no more than five lapses, confirmed by a CO test at the 12-month assessment. The secondary outcomes will be seven-day self-report point prevalence abstinence at three months and seven-day biochemically confirmed point prevalence abstinence at 12 months. To assess cost-effectiveness, costs will be estimated from a health service perspective and the EQ-5D will be used to estimate the QALY (Quality Adjusted Life Year) gain associated with each intervention. The comparison of smoking abstinence rates (and any other binary outcomes) between the two trial arms will be carried out using odds ratio as the outcome statistic and other related statistical tests. Exploratory subgroup analyses, including logistic regression analyses with interaction terms, will be conducted to investigate possible effect-modifying variables. Discussion The possible effect of self-help educational materials for the prevention of smoking relapse has important public health implications. Trial registration Current Controlled Trials ISRCTN36980856

Abstract Background Hypertension is a common major risk factor for stroke and coronary heart disease. Little is known about how achievement of financially incentivised and non-incentivised indicators of quality of care varies with deprivation, or about the effect of financial incentives on health inequalities in hypertension. General practices in the UK have received financial incentives for high quality care since 2004. This study set out to assess the variations in achievement of incentivised and non-incentivised quality indicators for hypertension by patient area deprivation, before and after the introduction of financial incentives. Methods Achievement of 14 quality indicators for hypertension in 304 patient participants in 18 general practices in Norfolk, England was assessed one year before (2003) and one year after (2005) the introduction of financial incentives. Four indicators were incentivised and 10 were non-incentivised. Each participant's postcode was linked to an index of multiple deprivation score. Results The range of achievement of incentivised quality indicators was 65-94% in the least deprived third of participants, and 77-94% in the most deprived third in 2003 and 2005 combined. For non-incentivised indicators, the range was 7-85% in the least deprived and 24-93% in the most deprived third. Achievement of incentivised quality indicators in 2003 and 2005 combined did not vary significantly by area deprivation. Achievement of three of 10 non-incentivised indicators was higher in participants from more deprived postcode areas: providing lifestyle advice (odds ratio 1.34, 95% confidence interval 1.00-1.79), assessment of peripheral vascular disease (1.54, 1.02-2.35) and electrocardiography (1.38, 1.04-1.82). Conclusions Participants from more deprived areas received at least the same, and sometimes better, quality of care than those from less deprived areas. Quality of care for hypertension in general practice may not follow the inequitable distribution seen with some other conditions.

Abstract Background Evidence demonstrates that measures are needed to optimise therapy and improve administration of medicines in care homes for older people. The aim of this study is to determine the clinical and cost effectiveness of a novel model of multi-professional medication review. Methods A cluster randomised controlled trial design, involving thirty care homes. In line with current practice in medication reviews, recruitment and consent will be sought from general practitioners and care homes, rather than individual residents. Care homes will be segmented according to size and resident mix and allocated to the intervention arm (15 homes) or control arm (15 homes) sequentially using minimisation. Intervention homes will receive a multi-professional medication review at baseline and at 6 months, with follow-up at 12 months. Control homes will receive usual care (support they currently receive from the National Health Service), with data collection at baseline and 12 months. The novelty of the intervention is a review of medications by a multi-disciplinary team. Primary outcome measures are number of falls and potentially inappropriate prescribing. Secondary outcome measures include medication costs, health care resource use, hospitalisations and mortality. The null hypothesis proposes no difference in primary outcomes between intervention and control patients. The primary outcome variable (number of falls) will be analysed using a linear mixed model, with the intervention specified as a fixed effect and care homes included as a random effect. Analyses will be at the level of the care home. The economic evaluation will estimate the cost-effectiveness of the intervention compared to usual care from a National Health Service and personal social services perspective. The study is not measuring the impact of the intervention on professional working relationships, the medicines culture in care homes or the generic health-related quality of life of residents. Discussion This study will establish the effectiveness of a new model of multi-professional clinical medication reviews in care homes, using novel approaches to recruitment and consent. It is the first study to undertake an examination of direct patient outcomes, together with an economic analysis. Trial Registration ISRCTN: ISRCTN90761620

Abstract Web services have become a key technology for bioinformatics, since life science databases are globally decentralized and the exponential increase in the amount of available data demands for efficient systems without the need to transfer entire databases for every step of an analysis. However, various incompatibilities among database resources and analysis services make it difficult to connect and integrate these into interoperable workflows. To resolve this situation, we invited domain specialists from web service providers, client software developers, Open Bio* projects, the BioMoby project and researchers of emerging areas where a standard exchange data format is not well established, for an intensive collaboration entitled the BioHackathon 2008. The meeting was hosted by the Database Center for Life Science (DBCLS) and Computational Biology Research Center (CBRC) and was held in Tokyo from February 11th to 15th, 2008. In this report we highlight the work accomplished and the common issues arisen from this event, including the standardization of data exchange formats and services in the emerging fields of glycoinformatics, biological interaction networks, text mining, and phyloinformatics. In addition, common shared object development based on BioSQL, as well as technical challenges in large data management, asynchronous services, and security are discussed. Consequently, we improved interoperability of web services in several fields, however, further cooperation among major database centers and continued collaborative efforts between service providers and software developers are still necessary for an effective advance in bioinformatics web service technologies.

Abstract Background Biologists need to perform complex queries, often across a variety of databases. Typically, each data resource provides an advanced query interface, each of which must be learnt by the biologist before they can begin to query them. Frequently, more than one data source is required and for high-throughput analysis, cutting and pasting results between websites is certainly very time consuming. Therefore, many groups rely on local bioinformatics support to process queries by accessing the resource's programmatic interfaces if they exist. This is not an efficient solution in terms of cost and time. Instead, it would be better if the biologist only had to learn one generic interface. BioMart provides such a solution. Results BioMart enables scientists to perform advanced querying of biological data sources through a single web interface. The power of the system comes from integrated querying of data sources regardless of their geographical locations. Once these queries have been defined, they may be automated with its "scripting at the click of a button" functionality. BioMart's capabilities are extended by integration with several widely used software packages such as BioConductor, DAS, Galaxy, Cytoscape, Taverna. In this paper, we describe all aspects of BioMart from a user's perspective and demonstrate how it can be used to solve real biological use cases such as SNP selection for candidate gene screening or annotation of microarray results. Conclusion BioMart is an easy to use, generic and scalable system and therefore, has become an integral part of large data resources including Ensembl, UniProt, HapMap, Wormbase, Gramene, Dictybase, PRIDE, MSD and Reactome. BioMart is freely accessible to use at http://www.biomart.org.

Abstract Background Self-administered questionnaires are becoming increasingly common in general practice. Much research has explored methods to increase response rates but comparatively few studies have explored the effect of questionnaire administration on reported answers. Methods The aim of this study was to determine the effect on responses of returning patient questionnaires to the respondents' medical practice or an independent researcher to questions relating to adherence and satisfaction with a GP consultation. One medical practice in Waveney primary care trust, Suffolk, England participated in this randomised trial. Patients over 18 years initiated on a new long-term medication during a consultation with a GP were randomly allocated to return a survey from their medical practice to either their medical practice or an independent researcher. The main outcome measures were self reported adherence, satisfaction with information about the newly prescribed medicine, the consultation and involvement in discussions. Results 274 (47%) patients responded to the questionnaire (45% medical practice, 48% independent researcher (95% CI -5 to 11%, p = 0.46)) and the groups appeared demographically comparable, although the high level of non-response limits the ability to assess this. There were no significant differences between the groups with respect to total adherence or any of the satisfaction scales. Five (4%) patients reported altering doses of medication in the medical practice group compared with 18 (13%) in the researcher group (P = 0.009, Fisher's exact test). More patients in the medical practice group reported difficulties using their medication compared to the researcher group (46 (35%) v 30 (21%); p = 0.015, Fisher's exact test). Conclusion Postal satisfaction questionnaires do not appear to be affected by whether they are returned to the patient's own medical practice or an independent researcher. However, returning postal questionnaires relating to detailed patient behaviours may be subject to response biases and further work is needed to explore this phenomena.

Objectives: The dental health of 73 workers previously exposed to mercury vapour at a chloralkali plant was studied and compared with that of 51 non-exposed referents., Methods: A record of oral, periodontal, gingival and mucosal conditions, including teeth, restorations, prostheses, and oral hygiene, was established during a 30 min examination. The participants' periodontal conditions were assessed according to the community periodontal index of treatment needs (CPITN). The results with the CPITN index were also compared with previously published data for another similar population., Results: There was no significant difference between the exposed workers and the referents with respect to the number of remaining teeth, amount of amalgam restorations, crowns, bridges, or endodontically treated teeth. The oral hygiene among the exposed workers was significantly better than among the referents, but the periodontal health conditions did not significantly differ between the two groups, nor from those of another Norwegian population., Discussion: The present results seem to contradict previous reports claiming tooth loss as a possible result of exposure to mercury vapour.

Objectives: The purpose of this investigation was to compare the degree of abrasion in vitro of two acrylic veneers and dental enamel using a dentifrice with and without fluoride., Methods: Ten specimens of each of the two acrylics and enamel were embedded in resin, and eventually polished to 1 micron with diamond paste. Specimens were brushed in a brushing machine with 10,000 double strokes using a dentifrice (Solidox, A/S Denofa) with and without fluoride. The abrasion was evaluated by the naked eye, by photographs and measured by means of profilometer., Results: One of the polymer materials (Dentacolor, Kulzer) showed a significantly higher resistance to abrasion than the other (Biodent, DeTrey), irrespective of fluoride treatment. Brushing with or without fluoride revealed no significant difference in degree of abrasion between the two acrylic materials. Dentacolor showed significantly higher abrasion resistance than enamel, whereas Biodent did not. There was no significant difference in the degree of abrasion of enamel using dentifrice with or without fluoride., Significance: Abrasion of acrylic veneering material differed greatly between brands, but did not seem to be influenced by the fluoride in toothpaste.

The concentrations of total mercury (B-Hg), inorganic mercury (B-IHg), and methyl mercury (B-MeHg) in whole blood, urinary mercury (U-Hg), and selenium in urine (U-Se) and whole blood (B-Se) were determined in 74 chloralkali workers previously exposed to Hg vapour, and compared with 51 age matched referents. Dental amalgam state, fish consumption, and exposure related indices were studied with regard to the determined elements. A significant relation between the surface of dental amalgam and U-Hg (Pearson's r = 0.63, p < 0.001) was found among the referents. Mean U-Se was significantly lower (p < 0.001) among the subjects previously exposed to Hg (34.1 nmol/mmol creatinine) compared with that for the referents (42.6 nmol/mmol creatinine). A significant negative relation between the cumulative Hg dose and U-Se was also found. The mechanisms and the clinical significance of these findings are not clear. No relation between current U-Hg and previous occupational exposure to Hg was found among subjects in whom exposure had ceased more than one year before the study.

The release of mercury vapor was determined from eleven different amalgams exposed to externally induced corrosion by galvanic contact with a dental casting gold alloy. The electrolyte was an artificial saliva solution at 37 degrees C. The corrosion rates of the amalgams could be divided into two groups corresponding to the grouping into conventional and high-copper materials. The mercury release rate decreased during the 24 h test period for all the amalgams except one containing indium. There was no significant difference in the total mercury release between the conventional and high-copper amalgams as groups. The same applied for the individual products, except the one containing indium, which released significantly more mercury vapor than the two products with the lowest release.

The effect of different electrolytes on the results from potentiodynamic polarization corrosion testing was studied for nine different dental alloys. In general, the difference in the results was greater between certain alloys using the same electrolyte than between the electrolytes with the same alloy. However, there were some differences between the electrolytes, most pronounced when testing dental amalgams. The electrolyte consisting of 1% NaCl seemed to offer the most corrosive environment. Darvell's and Fusayama's solutions were much less corrosive, at least for dental amalgam specimens. With regard to the ranking by corrosion sensitivity of the amalgams, only the results obtained by using Fusayama's solution were consistent with the clinical experience of the materials.

The number and in particular the diversity in types and composition of alloys used in dentistry are increasing, thus enhancing the need for predictive corrosion testing. No corrosion test is generally accepted as being both applicable to and relevant for all dental alloys. However, some methods have gained a certain recognition, and among these are the potentiodynamic polarization techniques. The purpose of the present work was to study the application, the reproducibility and the influence of some methodological variables on the results of potentiodynamic polarization corrosion testing. Embedded specimens of 18 different dental alloys, representing all major types, were subjected to anodic polarization scan within the potential range of -700 mV to 1000 mV (SCE). Artificial saliva, with and without organic compounds, and sodium sulfide solution were used as electrolytes. The results were processed on a microcomputer using locally developed software. The curves of current density versus potential showed fair reproducibility, with great differences between some of the alloys, showing a clear relationship to nobility or passivity of the alloy. There were marked differences between the results obtained in artificial saliva and in sodium sulfide solution, while addition of organic components to the artificial saliva only had a minor effect. The potentiodynamic polarization corrosion test supplies detailed information such as anodic charge, and open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. These are all useful when evaluating the corrosion properties of a dental alloy. An analysis of variance of the results in this study showed that possible differences between the alloys were clearly detectable with this method. However, for alloys releasing non-ionic products during corrosion/degradation, the method may be inappropriate. It is thus concluded that the method appears applicable as an in vitro corrosion test for most dental alloys, with the possible exception of amalgams.

The Rota-dent brush has been compared to conventional manual toothbrushes as to the abrasive effect on the dentin. Thirty-two teeth were embedded in epoxyresin. The test blocks were ground and polished, thereafter brushed with Jordan Soft, Jordan Blå Kjerne, Wisdom Plaque Master (hard) and three different Rota-dent brushes, Standardpoint, Hollow-cup and Longpoint. The brushing experiment was made in a test chamber filled with distilled water. After the brushing, the profiles of the brushtracks on the blocks were measured. On all the blocks, small tracks appeared which were not measurable. Conventional toothbrushes and Rota-Dent brushes used without dentifrice gave minimal abrasion on the dentin.

Dental amalgam emits mercury, especially during setting. In addition, the preparation of the amalgam and its compaction into the cavity involve unbound metallic mercury or create a waste product with free metallic mercury. The present study was performed to explore whether emission of mercury in these situations would measurably influence the individual urinary mercury concentration of dental patients as a result of a single-session treatment with dental amalgam restorations. Informed consent was obtained from the patients of nine children about to be treated with amalgam restorations as part of their regular dental care. The children delivered a total of five morning urine samples before, during, and after the treatment period. No effect on the urine mercury concentration was found during the treatment period. Conclusively, one single session of amalgam treatment did not per se represent a mercury exposure of sufficient quantity to be detectable in a longitudinal, individual study.

Professional commercial divers working with electrical cutting and welding sometimes experience a metallic taste phenomenon. An enquéte study among divers showed no influence of different equipment on the occurrence of such metallic taste, but it seems to occur less frequently in low salinity water. It has been suggested that this metallic taste phenomenon is due to increased corrosion rate of dental restorations, especially of amalgam. Experimental results recording the potential of amalgam specimens placed in the oral cavity of divers during welding, showed influence on the potential, and thus probably on the corrosion rate, during welding only when the diver came into direct contact with the water, e.g. through leakage in the suit.

Six mM fluoride had no effect on lactate production in LS cells incubated in Eagle's minimum essential medium. In Krebs-Ringer phosphate buffer with 10 mM glucose inhibition was found with 3mM fluoride. The fluoride effect was similar in aerobic and anaerobic conditions. Twelve mM fluoride had no inhibitory effect on ATP levels in LS cells.

Galvanic corrosion of amalgam, induced by contact with a type IV dental casting gold alloy, was determined under simulated oral conditions in an electrochemical cell. The effect of a pellicle layer formed by 1 h exposure to saliva in the oral cavity was determined. Pellicle on the amalgam had no effect on the maximum corrosion rate or the 2 h corrosion charge, whereas pellicle on the gold alloy substantially reduced both these parameters of the conventional low-copper amalgam; the corrosion of the high-copper amalgam was less and was not influenced by pellicle formation.

Sodium fluoride exhibited a dose dependent inhibitory effect on protein and DNA synthesis at concentrations from 1.3 mM in growing LS cells. The activity of ornithine decarboxylase (ODC) was slightly stimulated by 0.5 mM-NAF, but inhibited at 1.3 mM and above. The reduced enzyme activity seemed to be due to a reduced de novo formation of the enzyme caused by an inhibition of the protein synthesis. In spite of a reduction of ODC-activity, fluoride had no effect on the cellular polyamine content during the experimental period (10 hours).

Cells cultured in vitro can be adapted to grow in the presence of high concentrations of fluoride by stepwise increasing the fluoride concentration in the culture medium. Such cells seem to have the ability to exclude fluoride from intracellular compartments.

The percent pore area and the mean pore size were measured in specimens made of nine brands of composite resin restorative materials. The overall percent porosity ranged from 0.01 to 4.5%. The specimens for the study were prepared in two ways; by condensation or by pressure. Most of the materials, including all those chemically activated, showed more porosity in the condensed than in the pressure specimens. Reversed results emerged for two of the materials, and for another two, the specimens were similar in this respect. The mean pore sizes were smaller in the condensed than in the pressure specimens. Neither mean pore size nor total amount of porosities could be correlated to the curing method of the materials.

The susceptibility of amalgam to deviations in the preparation procedure produced an overall trend for both the setting dimensional stability and the number of porosities. The dimensional stability of ANA 2000 was the least affected by the deviations, while ANA 68 exhibited low susceptibility to the deviations when porosities are concerned. Lowered condensation pressure usually increased both the setting expansion and the number of porosities, and vice versa. Dispersalloy exhibited an increased number of porosities with both higher and lower condensation pressure. Except for ANA 2000, undertrituration caused increased expansion and porosities, while overtrituration resulted in increased contraction but minor effects on porosities. Lower mercury/alloy ratio increased the setting expansion and the number of porosities, while the response to a higher ratio was relatively small with the exception of a markedly increased setting expansion for ANA 68.

DNA synthesis in isolated nuclei from both fluoride sensitive and resistant LS cells was inhibited by fluoride at and above 3 mM. These fluoride concentrations also had an inhibitory effect on DNA synthesis in intact sensitive cells, but not in resistant cells. Due to previous findings that the intracellular fluoride concentration in the sensitive cells is only 30-40% of the extracellular, it is suggested that inhibition of DNA synthesis in intact cells is secondary to the inhibitory effect on protein synthesis.

The established cell line LS (mouse fibroblasts) has been adapted to grow at otherwise toxic concentrations of fluoride. Different substrains of adapted LS cells consumed less glucose and converted less of the glucose to lactate than the unadapted cells. Differences were also found in the two parameters dependent on the number of generations grown in the presence of fluoride. The more generations with fluoride, the less lactate was produced and the less glucose consumed.

Rats were exposed to fluoride (F) for up to 8 weeks through the drinking water containing 100 p.p.m. F. Urine samples were regularly collected, together with tissue samples of liver and kidney at termination. All samples were assayed for cyclic AMP. No F-effect was found on liver or kidney levels of cyclic AMP. In the urine from the F-exposed rats there was an overall increase in the cyclic AMP concentration, but a decreased or unaffected 24 hrs urinary excretion of cyclic AMP. However, the F-exposed rats exhibited a considerably lower diuresis than the control animals. Because a significant negative correlation was found between diuresis and urinary concentration of cyclic AMP, the material was corrected to similarity in the mean diuresis between the two groups. Then no effect of F-exposure could be detected either in the urinary concentration or the daily excretion of cyclic AMP.

Radioactive chromium accumulated in human erythrocytes exists in two forms: one bound to macromolecules, e.g., hemoglobin, and one in a low molecular weight form. Both forms are released from cells either spontaneously or as a result of toxic induction.

The aim of the study was to analyse the concentration levels of mercury and copper in urine, blood/blood plasma and saliva in relation to intra-oral electrical activity. Five Swedish Navy divers took part in the study in order to determine whether working submerged with electrical cutting equipment produced changes in the presence and level of oral galvanism and whether this posed a serious occupational health risk. The investigation concluded that the risk of seriously increased intra-oral electrical activity during welding or cutting activities was small. Development of the study is suggested, with long-term sampling of urine and blood samples of divers supported.

Twelve single crowns were cast in a silver-palladium alloy by six different casting techniques. Polished sections of the crowns were inspected and photographically recorded by light microscopy. The area of the inspected section of the casting and the number and area of pores were recorded on the photographs by means of a digitizing table connected to a microcomputer. A great number of defects were observed unevenly distributed in all castings. Only small variations were observed between the various casting techniques.

The correlation between microstructure, tarnish, and corrosion behavior of a commercial dental Ag-Pd-Cu-Au casting alloy after various heat treatments was studied. The attacked structural components were identified by comparing SEM micrographs with light optical micrographs taken after exposure of the alloy to a 2% Na2S solution and after dynamic polarization in de-aerated artificial saliva. The characteristic dynamic polarization curves for the alloy after the heat treatments were established. The results were verified by analogous testing of two experimental alloys with compositions similar to those of the analyzed components in the commercial alloy annealed at 600 degrees C for seven wk. The matrix of the commercial alloy was decomposed, according to the heat treatments, into varying proportions of a tarnish- and corrosion-resistant Cu- and Pd-rich component (A) and a nonresistant Ag-rich component (B). The presence of A considerably increased the tarnish rate of B, due to galvanic coupling. Age-hardening of the alloy increased the proportion of the tarnish- and corrosion-prone component B.

The sensitivity of the 51Cr release assay was evaluated with two known cytotoxic agents; fluoride and cadmium. The sensitivity was far less than that of other assays, e.g. growth inhibition of cultured cells, and additional a two-peaked dose-response curve was found with cadmium.

The galvanic currents between gold and amalgam were determined in vitro in aerated artificial saliva kept at 37 degrees C. Using conventional amalgam, the current between gold and amalgam was rapidly fluctuating, and both the magnitude of this fluctuation and the maximum current density increased with increased ratio between the gold and the amalgam surface area (G/A). The current density exhibited by the non-gamma 2 amalgam was lower, independent of G/A, and showed no fluctuations.

The fluoride sensitivity, determined as effect on protein synthesis (incorporation of 14C-leucine), of liver and kidney cells in suspension culture was exposed. The cells were freshly prepared by collagenase perfusion from rats given drinking water with or without addition of 100 p.p.m. (5.26 mM) fluoride for 9-28 weeks. The fluoride sensitivity of the liver cells from rats given fluoride sensitivity of the kidney cells from fluoride exposed and control rats appeared similar. Fluoride resistance (i.e. decreased sensitivity) may thus develop also in cells in vivo. When exposed to 3 mM NaF for 1 hour the intracellular concentration of fluoride in liver cells from fluoride exposed and controls animals were similar.

The potentials of 407 amalgam restorations have been determined in vivo. The measurements were performed with very high impedance equipment, and relative to a Ag/AgCl reference electrode. The readings varied from -23 mV to -595 mV, with 90% of the readings confined to within -127 mV to -431 mV and a mean value of -226.1 mV. Of the restorations, 394 were measured twice, and no significant difference could be found between the first and the second reading. During the study, eight new restorations were inserted. Their potentials varied from -180 mV to -565 mV, with a mean of -339.4 mV, which was significantly lower than that of the older restorations.

The fluoride sensitivity of cells released from rat livers and kidneys by collagenase perfusion was investigated by measuring effect on protein synthesis rate in vitro. Both cell types were sensitive to fluoride with clear concentration/effect relationships. Significant difference in sensitivity for fluoride between the cell types was found, with the kidney cells being the most sensitive type.

The effects of deviations from recommended preparation procedures on the compressive strength, modulus of elasticity, plastic deformation, toughness, and creep of four commercial amalgam alloys have been investigated. Deviations included changes in trituration time, mercury/alloy ratio, and condensation pressure. With regard to both compressive strength and creep, there were great differences in the susceptibility of different amalgam alloys to variations in manipulation. One conventional alloy showed almost no variation in compressive strength as a result of the deviations from the recommended preparation procedure. This material also showed much greater plastic deformation and fracture toughness than the other materials, making it less brittle and probably more resistant to bending forces. Dispersalloy exhibited both increased and decreased strength as a result of the deviations, while ANA 2000 and Revalloy only showed decreased strength. Some of the alterations for ANA 2000 and Revalloy resulted in a decrease in strength below an acceptable clinical level. Regarding the modulus of elasticity, only the conventional alloys were affected by the alterations in the preparation procedure. However, for the plastic deformation, the results were reversed; only the high-copper alloys were affected. The toughness of the specimens was decreased for all the alloys with the exception of one, which was insensitive to changes in the preparation procedure as far as compressive strength was concerned. One of the high-copper alloys showed the least change in creep relative to deviations in preparation procedures. Lowered condensation pressure increased the creep value for all the amalgams; and for the conventional alloys a lowered mercury/alloy ratio also resulted in increased creep.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluoride concentrations at and above 0.9 mM caused a progressive, concentration-related inhibition in the incorporation of both 14C-leucine and 3H-thymidine in LS cells incubated in medium with serum. The incorporation of leucine was more affected than that of thymidine. Lowering the pH enhanced the effect of fluoride on both. Removing serum from the incubation medium changed the effect of fluoride, particularly at low pH (7.0). Incorporation of leucine was then stimulated by low fluoride concentrations (0.5 and 0.9 mM), and the effect on thymidine incorporation was eradicated up to 1.3 mM-NaF. No differences were found in the pool and the specific activity of 14C-leucine in the fluoride exposed cells compared to control cells without fluoride (incubated at pH 7.4 in medium without serum). The cellular pool of 3H-thymidine decreased markedly during the incubation period, somewhat less in the fluoride exposed cells than in the control.

Fluoride decreased the initial uptake of 2-aminoisobutyric acid (AIB) in LS cells only in high (supralethal) concentrations and after several hours of exposure. The steady state level of AIB seemed somewhat more sensitive as it was halved after 23 hours exposure to 6 mM-NaF. The cellular levels of some natural amino acids were also reduced by fluoride. However, cells resistant to fluoride showed equally lowered levels of amino acids, indicating that the observed effect of fluoride on cellular amino acid levels may be of little importance.

The effect of 10 mM fluoride on glycerol production in vitro from rat epididymal adipocytes was investigated. Fluoride had no effect on the basal glycerol production, irrespective of the presence or absence of Ca++ and Mg++ ions. When stimulating the glycerol production with 10 mM theophylline, fluoride reduced the stimulation in the absence of either Ca++ or Mg++ or both. In the presence of both ions, fluoride had no effect on the theophylline stimulation. Fluoride also reduced the stimulative effect of adrenaline on glycerol production, but not that of glucagon. Increased adrenaline concentration could not overcome the inhibitory effect of fluoride.

The possible role of adenosine 3',5'-monophosphate (cAMP) in the cytotoxic effect of fluoride was investigated in fluoride sensitive mouse fibroblasts (LS) and a subline of LS resistant to 6 mM fluoride (FR6). In both cell lines, growth was inhibited by dibutyryl-cAMP, prostaglandin (PG)E2 and theophylline, FR6 being somewhat more sensitive to these agents than LS. FR6 had lower basal cAMP levels in the intact cells and lower basal adenylate cyclase activity in the homogenate preparation than LS, but the percentual response of intact cells or adenylate cyclase preparations to PGE1 or PGE2 was about the same in the two cell lines, and the sensitivity of the adenylate cyclase to fluoride was similar. No measurable increase in cAMP content was found in either LS or FR6 after exposure of the intact cells to various concentrations of fluoride for various times. The present results indicate that the development of fluoride resistance in these cells is not due to decreased sensitivity to cAMP, and probably not due to altered cAMP-formation in response to fluoride. The growth inhibitory and cytotoxic effects of fluoride in LS cells is probably not mediated through cAMP.

Uptake of 51Cr-chromate by freshly collected human erythrocytes was inhibited by 90 mM sodium fluoride only in cells preincubated with fluoride. In vitro storage also increased the sensitivity of the cells: 90 mM NaF clearly inhibited the uptake of chromate in cells stored in vitro for 5 weeks. Gel chromatography revealed two forms of 51Cr within the cells, one of small molecular weight, which thin layer chromatography indicated was unchanged chromate; the other form was apparently bound to macromolecules such as hemoglobin.