A model of the UV skin dose distribution in paediatric whole-body phototherapy.

The radiance equation is applied in this study to model the ultraviolet (UV) radiation dose distribution over the skin in paediatric and adult patients treated in a whole-body phototherapy cabin. This approach extends a previously published model of UV radiation dose based on thermal radiation exchange between surfaces (Colemanet al2020Biomed. Phys. Eng. Express6055023). The new model makes it feasible to predict the distribution of UV irradiance over the head, trunk and legs in patients of varying height. The modelled irradiance distributions to directly lamp-facing skin surfaces agree to within 10% of those measured in simulated clinical paediatric treatments in a modern narrowband UVB treatment cabin. For a 10 year old (of height 1.36 m), for example, the model and the clinical measurements both show a UV radiation dose to the face that is around 25% more than that in an adult (of height 1.8 m). The dose to the crown of the head of a 10 year old is both predicted and measured to be more than double that of an adult. The automated dosimetry system, incorporated within the treatment cabin, is also predicted to overestimate irradiance to the body by between 10% and 25% in patients aged between 10 and 4 years (height 1.36-1.0 m). The value of the model and its implications for paediatric whole-body UV treatment in adult-size whole-body treatment cabins are considered.

A thermal radiation exchange model of whole-body UV phototherapy.

A novel model of the skin dose in whole-body UV phototherapy treatment cabins is presented. The model is based on an analysis of the thermal radiation exchange between two surfaces, in this case the UV source and the patient. It is shown to allow analytical treatment of the multiple internal reflections in a treatment cabin that account for around 40% of the skin irradiance. The model provides predictions of the absolute irradiance at the skin and shielding factors in seven different UVA and NB-UVB cabins that are within 6% of those measured using a calibrated radiometer and within 12% for all nine cabins. The model predicts reducing skin irradiances with increasingly patient size, a trend demonstrated in clinical measurements. The exact sensitivity to patient size in automated cabin dosimetry systems, however, varies with in-built sensor positioning. The potential to extend the use of the model to investigate improved design of automated dosimetry systems is discussed.

Interprofessional education in dentistry.

A collaborative health workforce is required to respond to the increasing demands on healthcare resources. Various national and international bodies are promoting interprofessional education (IPE) as a method to provide this collaborative health workforce. IPE is therefore becoming increasingly prominent within healthcare training and will be an essential aspect of dental education. A literature search was completed to provide this narrative review which will introduce IPE, discuss the rationale for IPE within dentistry and the challenges faced. Based on current literature, it will provide practical advice on how to implement an effective IPE learning activity within dentistry.

Toward dissecting the etiology of schizophrenia: HDAC1 and DAXX regulate GAD67 expression in an in vitro hippocampal GABA neuron model.

Schizophrenia (SZ) is associated with GABA neuron dysfunction in the hippocampus, particularly the stratum oriens of sector CA3/2. A gene expression profile analysis of human postmortem hippocampal tissue followed by a network association analysis had shown a number of genes differentially regulated in SZ, including the epigenetic factors HDAC1 and DAXX. To characterize the contribution of these factors to the developmental perturbation hypothesized to underlie SZ, lentiviral vectors carrying short hairpin RNA interference (shRNAi) for HDAC1 and DAXX were used. In the hippocampal GABA neuron culture model, HiB5, transduction with HDAC1 shRNAi showed a 40% inhibition of HDAC1 mRNA and a 60% inhibition of HDAC1 protein. GAD67, a enzyme associated with GABA synthesis, was increased twofold (mRNA); the protein showed a 35% increase. The expression of DAXX, a co-repressor of HDAC1, was not influenced by HDAC1 inhibition. Transduction of HiB5 cells with DAXX shRNAi resulted in a 30% inhibition of DAXX mRNA that translated into a 90% inhibition of DAXX protein. GAD1 mRNA was upregulated fourfold, while its protein increased by ~30%. HDAC1 expression was not altered by inhibition of DAXX. However, a physical interaction between HDAC1 and DAXX was demonstrated by co-immunoprecipitation. Inhibition of HDAC1 or DAXX increased expression of egr-1, transcription factor that had previously been shown to regulate the GAD67 promoter. Our in vitro results point to a key role of both HDAC1 and DAXX in the regulation of GAD67 in GABAergic HiB5 cells, strongly suggesting that these epigenetic/transcription factors contribute to mechanisms underlying GABA cell dysfunction in SZ.

Automated registration of optical coherence tomography and dermoscopy in the assessment of sub-clinical spread in basal cell carcinoma.

Optical coherence tomography (OCT) has been shown to be of clinical value in imaging basal cell carcinoma (BCC). A novel dual OCT-video imaging system, providing automated registration of OCT and dermoscopy, has been developed to assess the potential of OCT in measuring the degree of sub-clinical spread of BCC. Seventeen patients selected for Mohs micrographic surgery (MMS) for BCC were recruited to the study. The extent of BCC infiltration beyond a segment of the clinically assessed pre-surgical border was evaluated using OCT. Sufficiently accurate (<0.5 mm) registration of OCT and dermoscopy images was achieved in 9 patients. The location of the OCT-assessed BCC border was also compared with that of the final surgical defect. Infiltration of BCC across the clinical border ranged from 0 mm to >2.5 mm. In addition, the OCT border lay between 0.5 mm and 2.0 mm inside the final MMS defect in those cases where this could be assessed. In one case, where the final MMS defect was over 17 mm from the clinical border, OCT showed >2.5 mm infiltration across the clinical border at the FOV limit. These results provide evidence that OCT allows more accurate assessment of sub-clinical spread of BCC than clinical observation alone. Such a capability may have clinical value in reducing the number of surgical stages in MMS for BCC. There may also be a role for OCT in aiding the selection of patients most suitable for MMS.

Ultraviolet A1 phototherapy: a British Photodermatology Group workshop report.

Whole-body ultraviolet (UV)A1 (340-400 nm) phototherapy was first introduced 30 years ago, but is currently available in the UK in only three dermatology departments. A workshop to discuss UVA1 was held by the British Photodermatology Group in May 2009, the aim of which was to provide an overview of UVA1 phototherapy and its role in practice, and to identify areas in which further studies are required. The conclusions were that UVA1 phototherapy is an effective treatment in several inflammatory skin diseases, including localized scleroderma and atopic eczema (AE); however, deficiencies and limitations exist in the published evidence base. For most diseases, such as AE, other treatments also exist, which are generally more effective than UVA1. However, for some diseases, particularly morphoea, the evidence of efficacy is stronger for UVA1 than for other treatments. Acute adverse effects of UVA1 are minimal. The risk of long-term adverse effects, particularly skin cancer, is unknown. Medium to high doses of UVA1 are needed for efficacy in most situations, but the equipment to deliver such doses is large, expensive and difficult to install. UVA1 is currently underprovided, and the recommendation of the workshop is that more tertiary centres should have access to UVA1 phototherapy in the UK.

Magnetic resonance spectroscopy biomarkers in premanifest and early Huntington disease.

OBJECTIVES: To evaluate in vivo brain metabolite differences in control subjects, individuals with premanifest Huntington disease (pre-HD), and individuals with early HD using ¹H magnetic resonance spectroscopy (MRS) and to assess their relationship with motor performance. METHODS: Eighty-five participants (30 controls, 25 pre-HD, and 30 early HD) were recruited as part of the TRACK-HD study. Eighty-four were scanned at 3 T with single-voxel spectroscopy in the left putamen. Disease burden score was >220 among pre-HD individuals. Subjects underwent TRACK-HD motor assessment including Unified Huntington's Disease Rating Scale (UHDRS) motor scoring and a novel quantitative motor battery. Statistical analyses included linear regression and one-way analysis of variance. RESULTS: Total N-acetylaspartate (tNAA), a neuronal integrity marker, was lower in early HD (∼15%) vs controls (p < 0.001). N-acetylaspartate (NAA), a constituent of tNAA, was lower in pre-HD (∼8%) and early HD (∼17%) vs controls (p < 0.05). The glial cell marker, myo-inositol (mI), was 50% higher in early HD vs pre-HD (p < 0.01). In early HD, mI correlated with UHDRS motor score (R² = 0.23, p < 0.05). Across pre-HD and early HD, tNAA correlated with performance on a tongue pressure task (R² = 0.30, p < 0.0001) and with disease burden score (R² = 0.17, p < 0.005). CONCLUSIONS: We demonstrate lower putaminal tNAA in early HD compared to controls in a cross-section of subjects. A novel biomarker role for mI in early HD was also identified. These findings resolve disagreement in the literature about the role of MRS as an HD biomarker. We conclude that putaminal MRS measurements of NAA and mI are promising potential biomarkers of HD onset and progression.

Calibration accuracy of hospital-based non-invasive blood pressure measuring devices.

Accurate blood pressure (BP) measurement is dependent on a trained observer using validated and properly maintained equipment. BP devices should be checked regularly to ensure that their calibration remains within the European Standard specification of +/-3 mm Hg. This study assessed the air leakage rates and calibration accuracy of BP devices in use at a large teaching hospital, using a calibrated electronic pressure gauge as reference. Air leakage rates were recorded over 1 min and static pressures were recorded at 250/200/150/100/50/0 mm Hg for computer download and analysis. A total of 127 devices were assessed (18 mercury, 62 aneroid and 47 automated). In total, 22 different models of devices were available, of which 11 were automated and only 4 had published evidence of a validation using a recognized protocol (British Hypertension Society, Association for the Advancement of Medical Instrumentation or International Protocol). Only 3% (n=4) of devices had an air leakage rate within 4 mm Hg per min and 25% (n=32) of devices failed to meet the European calibration standard of +/-3 mm Hg. Respective failure rates were 6% (1/18) for mercury, 31% (19/62) for aneroid and 26% (12/47) for automated devices. Inaccurate BP measurement of only 3 mm Hg can have detrimental effects in the patient. This study shows a quarter of devices currently in use at a large teaching hospital to have an unacceptable calibration error. Regular maintenance and calibration checks are vital in ensuring that BP is measured as accurately as possible.

A passive acoustic device for real-time monitoring of the efficacy of shockwave lithotripsy treatment.

Extracorporeal shockwave lithotripsy (ESWL) is the preferred modality for the treatment of renal and ureteric stone disease. Currently X-ray or ultrasound B-scan imaging are used to locate the stone and to check that it remains targeted at the focus of the lithotripter during treatment. Neither imaging modality is particularly effective in allowing the efficacy of treatment to be judged during the treatment session. A new device is described that, when placed on the patient's skin, can passively monitor the acoustic signals that propagate through the body after each lithotripter shock, and which can provide useful information on the effectiveness of targeting. These acoustic time histories are analyzed in real time to extract the two main characteristic peak amplitudes (m(1) and m(2)) and the time between these peaks (t(c)). A set of rules based on the acoustic parameters was developed during a clinical study in which a complete set of acoustic and clinical data was obtained for 30 of the 118 subjects recruited. The rules, which complied with earlier computational fluid dynamics (CFD) modeling and in vitro tests, allow each shock to be classified as "effective" or "ineffective." These clinically-derived rules were then applied in a second clinical study in which complete datasets were obtained for 49 of the 85 subjects recruited. This second clinical study demonstrated almost perfect agreement (kappa = 0.94) between the number of successful treatments, defined as >50% fragmentation as determined by X-ray at the follow-up appointment, and a device-derived global treatment score, TS(0), a figure derived from the total number of effective shocks in any treatment. The acoustic system is shown to provide a test of the success of the treatment that has a sensitivity of 91.7% and a specificity of 100%. In addition to the predictive capability, the device provides valuable real-time feedback to the lithotripter operator by indicating the effectiveness of each shock, plus an indication TS(t) of the cumulative effectiveness of the shocks given so far in any treatment, and trends in key parameters. This feedback would allow targeting adjustments to be made during treatment. An example is given of its application to mistargeting because of respiration.

Acoustic streaming in lithotripsy fields: preliminary observation using a particle image velocimetry method.

This study considers the acoustic streaming in water produced by a lithotripsy pulse. Particle image velocimetry (PIV) method was employed to visualize the acoustic streaming produced by an electromagnetic shock wave generator using video images of the light scattering particles suspended in water. Visualized streaming features including several local peaks and vortexes around or at the beam focus were easily seen with naked eyes over all settings of the lithotripter from 10 to 18 kV. Magnitudes of the peak streaming velocity measured vary in the range of 10-40 mm s(-1) with charging voltage settings. Since the streaming velocity was estimated on the basis of a series of the video images of particles averaged over 1/60s, the time resolution limited by the video frame rate which is 1-2 orders of magnitude larger than driving acoustic activities, measured velocities are expected to be underestimated and were shown a similar order of magnitude lower than those calculated from a simple theoretical consideration. Despite such an underestimation, it was shown that, as predicted by theory, the magnitude of the streaming velocity measured by the present PIV method was proportional to acoustic intensity. In particular it has almost a linear correlation with peak negative pressures (r=0.98683, p=0.0018).

Guidelines for dosimetry and calibration in ultraviolet radiation therapy: a report of a British Photodermatology Group workshop.

This report examines the dosimetry of ultraviolet (UV) radiation applied to dermatological treatments, and considers the definition of the radiation quantities and their measurement. Guidelines are offered for preferred measurement techniques and standard methods of dosimetry. The recommendations have been graded according to the American Joint Committee on Cancer classification of strength of recommendation and quality of evidence (summarized in Appendix 5).

Macromolecular leakage beneath full cast crowns: A two-year in vitro investigation.

STATEMENT OF PROBLEM: Most microleakage studies have used low molecular weight dyes or isotopes rather than clinically relevant materials such as lipopolysaccharides (LPSs) or cell wall materials that have been shown to provoke inflammatory reactions in the dental pulp. PURPOSE: This investigation evaluated the leakage (diffusion) of fluorescently labeled LPS and dextran beneath cast-gold crowns luted with 3 cements. MATERIAL AND METHODS: Thirty extracted molars were prepared for crowns. Ten crowns with access ports (facial or lingual) were cast in gold and luted with zinc phosphate, glass ionomer, and an adhesive resin cement onto their preparations. Teeth and crowns with filters inserted into the ports were immersed in a solution of labeled macromolecules (TRITC-LPS, FITC-dextran) and evaluated for leakage every month for 24 months. Filters were retrieved and analyzed with fluorescent microscopy. RESULTS: All filters retrieved from crowns luted with zinc phosphate, glass ionomer, and adhesive resin cements demonstrated no detectable leakage and were negative for both FITC-dextran and TRITC-LPS for all evaluation periods. CONCLUSION: For the 24 months of this investigation, zinc phosphate, Ketac-Cem, and C&B-Metabond were equally effective at preventing leakage of detectable molecular concentrations of LPS and dextran to the level of the access ports.

A multifunctional, provisional, implant-retained fixed partial denture.

This article describes the modification of a procedure for fabricating a laboratory-processed, metal-reinforced, acrylic resin provisional restoration that becomes an implant-retained fixed partial denture. The modification involves the incorporation of patrix and matrix components into a cast metal framework. The prosthesis can be used as an alternative to a removable radiologic stent and surgical guide. It can function as a surgical guide during implant placement and help retract the buccal mucogingival flap during implant placement. The prosthesis also can be used as an aid in locating the implant during stage II surgery. Finally, the pontics can be converted into an implant-supported provisional restoration immediately after the implant prosthetic components are attached to the uncovered implants.

Macromolecular leakage beneath complete cast crowns. A 6-month in vitro investigation using microfluorimetry.

OBJECTIVE: This investigation evaluated the leakage (diffusion) of lipopolysaccharide and dextran beneath cast-gold crowns luted with one of three cements. METHOD AND MATERIALS: Thirty extracted molars were prepared for crowns. Thirty crowns with access ports (facial or lingual) were cast in gold and luted to their preparations with zinc phosphate, glass-ionomer, or an adhesive resin cement (10 per group). Teeth and crowns with filters inserted in the ports were immersed in a solution of labeled macromolecules (tetramethylrhodamine isothiocyanate-labeled lipopolysaccharide and fluorescein isothiocyanate-labeled-dextran) and evaluated for leakage at 2 weeks and 1, 2, 3, 4, 5, and 6 months. Filters were retrieved and analyzed with microfluorimetry. RESULTS: No filters retrieved from any crowns demonstrated any detectable leakage, and all filters were negative for both dextran and lipopolysaccharide for all evaluation periods. CONCLUSION: For the 6 months of this investigation, zinc phosphate, glass-ionomer, and adhesive resin cements were equally effective at preventing leakage of detectable molecular concentrations of lipopolysaccharide and dextran to the level of the access ports in the absence of thermal or mechanical stress.

Traceable calibration of ultraviolet meters used with broadband, extended sources.

A calibration system has been developed to provide increased accuracy in the measurement of the irradiance responsivity appropriate for UV meters used with broadband, extended sources of the type employed in phototherapy. The single wavelength responsivity of the test meter is obtained in the wavelength range 250-400 nm by intercomparison with a transfer standard meter in a narrow, monochromatic beam. Traceability to primary standard irradiance scales is provided via the National Measurement System with a best uncertainty of 7% (at 95% confidence). The effective responsivity of the test meter, when used with broadband extended sources, is calculated using the measured spectral and angular response of the meter and tabulated data on the spectral and spatial characteristics of the source radiance. The uncertainty in the effective responsivity, independent of the source variability, is estimated to be 10% (at 95% confidence). The advantages of this calibration system over existing approaches are discussed.

Macromolecular leakage beneath full cast crowns. Part III: The diffusion of lipopolysaccharide and dextran.

STATEMENT OF PROBLEM: Most microleakage studies have used low molecular weight dyes or isotopes rather than clinically relevant materials, such as lipopolysaccharides or cell wall materials, that have been shown to provoke inflammatory reactions in the dental pulp. PURPOSE: This study evaluated the leakage (diffusion) of lipopolysaccharide and dextran beneath cast gold crowns luted with 3 cements. MATERIALS AND METHODS: Thirty extracted molars were prepared for crowns. Ten crowns with access ports (facial or lingual) were cast in gold and luted with zinc phosphate, glass ionomer, and an adhesive resin cement onto their preparations. Teeth and crowns with filters inserted into the ports were immersed in a solution of labeled macromolecules (TRITC-LPS, FITC-dextran) and evaluated for leakage at 2 weeks, and 1, 2, 3, 4, 5, and 6 months. Filters were retrieved and analyzed with fluorescent microscopy. RESULTS: All filters retrieved from crowns luted with zinc phosphate, glass ionomer, and adhesive resin cements demonstrated no detectable leakage and were negative for both FITC-dextran and TRITC-lipopolysaccharide at all evaluation periods. CONCLUSION: Leakage of lipopolysaccharides and dextran did not occur during the period of this study. For the length of this investigation, zinc phosphate, Ketac-Cem, and C&B-Metabond were equally effective at preventing leakage of detectable molecular concentrations of lipopolysaccharide and dextran to the level of the access ports.

Acoustic performance and clinical use of a fibreoptic hydrophone.

Initial clinical experience with the use of an optical fibre hydrophone for in vivo ultrasound dosimetry is reported. The hydrophone, originally described by Beard and Mills (1997), operates as an extrinsic, low-finesse Fabry-Perot optical sensor where acoustically-induced thickness changes in a polymer film modulate the phase difference between light beams reflected from the two surfaces of the film. The pressure waveforms from the sensor are compared with those from a calibrated piezoelectric polymer membrane hydrophone. The sensor is found to have a frequency resonance at around 12 MHz, corresponding to the thickness mode of the 50-micron polymer film. The directional responses at 0.16 MHz, 1.0 MHz and 5.0 MHz are found to be similar to those predicted for a plane piston receiver with the same diameter as that of the polymer film (400 microns). The performance of the sensor as a broad-band hydrophone is degraded by the relatively low acoustical impedance of the adhesive used in the fibre-film bond. The hydrophone was used in the clinic for measurement of acoustic pressures within the ureter of 4 patients undergoing clinical extracorporeal shock-wave lithotripsy on a Dornier HM3 lithotripter. Pressures in the range 0.5 to 5.0 MPa were recorded in the ureter at positions over 10 cm from the renal pelvis. Problems related to the clinical use of the sensor, including instability in the sensitivity of the sensor following handling and its mechanical strength in high-amplitude acoustic fields, are discussed.

Restorations using osseointegrated implants with resilient attachments.

This article presents a clinical report of the prosthodontic treatment of a patient with a partially edentulous mandible. Osseointegrated titanium implants and resilient attachments for overdentures were used to retain and stabilize a mandibular overdenture that restored the patient's occlusion. This provided a simple and economical solution to retention and stability problems for a patient with a partially edentulous mandible.

An injection technique for generating direct resin post and core patterns.

An injection technique can be used to rapidly generate direct post and core patterns with autopolymerizing acrylic resin. The technique uses an autopolymerizing acrylic resin, a serrated plastic pin, and a syringe with a disposable needle tube and plug to inject acrylic resin into the root canal. The technique is simple, accurate, and faster than the bead-brush technique and eliminates some of its shortcomings.