Arginine Metabolism in Supragingival Oral Biofilms as a Potential Predictor of Caries Risk

INTRODUCTION

Ammonia production via the arginine deiminase system (ADS) of oral bacteria can function to reduce the cariogenicity of oral biofilms by neutralizing glycolytic acids that cause tooth demineralization.

OBJECTIVES

This cohort study investigated the relationship between ADS activity and bacterial profile changes of supragingival biofilms with caries experience among children over time.

METHODS

A total of 79 children aged 2 to 7 y at baseline were assessed every 6 mo for a period of 18 mo. Children were grouped as caries free (CF), caries active with enamel lesions (CAE), or caries active with dentin lesions (CA). Supragingival plaque samples were collected from caries-free surfaces (PF) and from enamel (PE) and dentin (PD) lesions. Plaque ADS activity was measured by monitoring citrulline production from arginine and compared with ribosomal 16S rRNA-derived taxonomic profiles for the same samples.

RESULTS

At baseline, 37% of the children were CF, 34% CAE, and 29% CA. At 18 mo, 26% were CF, 41% CAE, 23% CA, and 10% were caries experienced (new restorations but no caries activity). Throughout the study period, ADS activity was significantly higher in the CF group than the CA group (P < 0.0001), and ADS activity in the PF samples was significantly higher than in the PE and PD samples (P < 0.0001). Distance-based redundancy analysis showed that the bacterial communities could be differentiated when plaque samples are grouped into levels of high and low ADS activity.

CONCLUSIONS

There is a positive correlation between caries activity and low arginolytic capacity of the supragingival oral biofilms of children and tooth surfaces over time. Measurements of arginine metabolism via ADS may be useful to differentiate the caries risk of individuals and tooth surfaces.

KNOWLEDGE TRANSFER STATEMENT

Findings from this study support the development of new strategies for caries risk assessment and prevention based on modulation of the virulence of the oral microbiome through arginine metabolism in supragingival biofilms.

Enhanced coupling of broadband light into amorphous silicon via periodic nanoplasmonic arrays

Achieving enhanced coupling of solar radiation over the full range of the silicon absorption spectrum up to the bandgap is essential for increased efficiency of solar cells, especially thin film versions. While many designs for enhancing trapping of radiation have been explored, detailed measurements of light scattering inside silicon cells is still lacking. Here, we demonstrate experimentally and computationally that plasmonic-assisted localized and traveling modes can efficiently couple red and infrared radiation into ultrathin amorphous silicon (a-Si) layers. Utilizing patterned periodic arrays of aluminum nanostructures on thin a-Si, we perform specular and diffuse reflectivity and transmission measurements over a broad spectrum. Based on these results, we are able to separate parasitic absorption in aluminum plasmonic arrays from enhanced light absorption in the 200 nm thick amorphous silicon layer, as compared to a blank silicon layer. We discover a very efficient near-infrared a-Si absorption mechanism that occurs at the transition from the radiative to evanescent diffractive coupling, analogous to earlier surface-enhanced infrared studies. These results represent a direct demonstration of enhanced radiation coupling into silicon due to large angle scattering and show a path forward to improved ultrathin solar cell efficiency.

Transferrin-Targeted Nanoparticles Containing Zoledronic Acid as a Potential Tool to Inhibit Glioblastoma Growth

The treatment of glioblastoma (GBM) is a challenge for the biomedical research since cures remain elusive. Its current therapy, consisted on surgery, radiotherapy, and concomitant chemotherapy with temozolomide (TMZ), is often uneffective. Here, we proposed the use of zoledronic acid (ZOL) as a potential agent for the treatment of GBM. Our group previously developed self-assembling nanoparticles, also named PLCaPZ NPs, to use ZOL in the treatment of prostate cancer. Here, we updated the previously developed nanoparticles (NPs) by designing transferrin (Tf)-targeted self-assembling NPs, also named Tf-PLCaPZ NPs, to use ZOL in the treatment of brain tumors, e.g., GBM. The efficacy of Tf-PLCaPZ NPs was evaluated in different GBM cell lines and in an animal model of GBM, in comparison with PLCaPZ NPs and free ZOL. Tf-PLCaPZ NPs were characterized by a narrow size distribution and a high incorporation efficiency of ZOL. Moreover, the presence of Tf significantly reduced the hemolytic activity of the formulation. In vitro, in LN229 cells, a significant uptake and cell growth inhibition after treatment with Tf-PLCaPZ NPs was achieved. Moreover, the sequential therapy of TMZ and Tf-PLCaPZ NPs lead to a superior therapeutic activity compared to their single administration. The results obtained in mice xenografted with U373MG, revealed a significant anticancer activity of Tf-PLCaPZ NPs, while the tumors remained unaffected with free TMZ. These promising results introduce a novel type of easy-to-obtain NPs for the delivery of ZOL in the treatment of GBM tumors.

Preliminary evaluation of a radioactive waste repository safety performance by a Monte Carlo simulation-based reliability model

Disposal facilities are designed to provide long-term isolation of the wastes from the human environment by means of a system of barriers, both engineered and natural. In this regard, it is required that the containment function of the multi-barrier system be evaluated by a quantitative risk analysis procedure, also called performance assessment. This entails the implementation of a Probabilistic Safety Assessment model for representing the stochastic failure behavior of the repository barriers, estimating the release rates of radionuclides into the groundwater stream and the doses from subsequent ingestion of drinking water. To this aim, a Monte Carlo simulation scheme is provided within a reliability modelling approach for the safety performance analysis of a repository, accounting also for barrier degradation processes. An application to a case study of the literature is presented to validate the approach and demonstrate its simplicity and flexibility.

How do memory clinics compare with traditional old age psychiatry services?

METHODS

100 consecutive referrals to the Northern Memory Clinic (NMC) were compared with 100 referrals to a traditional Old Age Psychiatry (OAPsych) service in the same city in terms of demographic variables, cognitive function (assessed by the Mini-Mental State Examination), and diagnosis. The study also examined the ability of psychometric assessments (CAMCOG, MMSE, Trail-Making Tests A & B, Word Fluency) and CT scans included in the NMC assessment to differentiate between those with and without DSM-IV dementia.

RESULTS

NMC patients were significantly younger than OAPsych patients, had lower levels of cognitive impairment, and had a wider range of diagnoses. The NMC patients who were diagnosed as having dementia were found to be at least 2 years earlier in the course of the disease than those seen by the OAPsych team. The CAMCOG and MMSE were proved to be effective at distinguishing between patients diagnosed as dementing versus non-dementing with cut-offs of 82/83 and 23/24 respectively, confirming previous findings. The Memory subscale of the CAMCOG, though much shorter, was equally as effective using a cut-off of 20/21. Trail-Making Tests, Word Fluency (FAS), and measurement of the minimum width of the medial temporal lobe (MTL) on angled CT scans were poor indicators of dementia in this sample.

CONCLUSIONS

This study confirms that the memory clinic is targeting a distinct patient group compared to traditional old age psychiatry services, is identifying cases of dementia much earlier, and as such has potential to make valuable contributions to patient care.

A randomized controlled trial of Moderation-Oriented Cue Exposure

OBJECTIVE

A randomized controlled trial was conducted to examine the effectiveness of Moderation-Oriented Cue Exposure (MOCE) in comparison to Behavioral Self-Control Training (BSCT). The main hypothesis was that MOCE would be more effective than BSCT among a sample of problem drinkers aiming at moderate drinking. A subsidiary hypothesis was that MOCE would be relatively more effective than BSCT among problem drinkers with higher levels of alcohol dependence.

METHOD

Clients (N = 91; 75% men) were randomly allocated to either MOCE or BSCT. Treatment was delivered in weekly sessions by two trained therapists, in a nested design in which therapists switched to the alternative treatment modality approximately halfway through the trial. Follow-up was carried out 6 months following posttreatment assessment, with 85% successful contact.

RESULTS

There was no evidence for the general superiority of MOCE over BSCT. The subsidiary hypothesis was not confirmed. A subsample of clients (n = 14) showing levels of dependence at baseline above the commonly accepted cut-point for a moderation goal (Severity of Alcohol Dependence Questionnaire [SADQ] > 29) showed outcomes at least as favorable as those below the cut-point. The validity of self-reports of alcohol consumption and problems was supported by significant relationships with liver function tests (gamma-glutamyl transferase and alanine transferase).

CONCLUSIONS

These results provide no grounds for the replacement of BSCT by MOCE in routine, moderation-oriented treatment practice. Assuming they prefer it to abstinence and that it is not contra-indicated on other grounds, there seems no reason why clients showing a higher level of dependence (SADQ = 30-45) should not be offered a moderation goal.

Impaired Control Scale: cross-validation and relationships with treatment outcome

AIMS

(1) To cross-validate Australian findings on the Impaired Control Scale (ICS) in an English sample of problem drinkers. (2) To examine a possible improvement to the scoring of the ICS. (3) To explore the relationship of the ICS to treatment outcome.

DESIGN

In a repeated measures design, questionnaires and interviews were administered by trained staff during treatment and again at 6 months follow-up.

SETTING

Two alcohol and drug treatment services in Newcastle and Liverpool (UK).

PARTICIPANTS

Two hundred and twenty-nine problem drinkers attending as in- or outpatients, with abstinence or moderation treatment goals.

MEASUREMENTS

ICS scores; typical weekly alcohol consumption (units); degree of alcohol-related problems; severity of alcohol dependence; and classification of outcome using consumption levels and current alcohol-related problems, with collateral confirmation of self-reports.

FINDINGS

The satisfactory reliability and validity of the ICS was confirmed in an English sample of problem drinkers in treatment. An improved "substitution method" of scoring was developed to give a single measure of impaired control for all subjects irrespective of degree of attempted control. ICS scores were significantly correlated with treatment outcome and, among a subgroup of subjects who had aimed at abstinence but failed, predicted outcome status after the effects of degree of dependence had been extracted.

CONCLUSIONS

Impaired control over alcohol consumption can be measured in a reliable and valid fashion by the ICS. The ICS has potential uses in research on impaired control and as a clinical assessment tool.