A cross-sectional ecological analysis of international and sub-national health inequalities in commercial geospatial resource availability.

BACKGROUND: Commercial geospatial data resources are frequently used to understand healthcare utilisation. Although there is widespread evidence of a digital divide for other digital resources and infra-structure, it is unclear how commercial geospatial data resources are distributed relative to health need. METHODS: To examine the distribution of commercial geospatial data resources relative to health needs, we assembled coverage and quality metrics for commercial geocoding, neighbourhood characterisation, and travel time calculation resources for 183 countries. We developed a country-level, composite index of commercial geospatial data quality/availability and examined its distribution relative to age-standardised all-cause and cause specific (for three main causes of death) mortality using two inequality metrics, the slope index of inequality and relative concentration index. In two sub-national case studies, we also examined geocoding success rates versus area deprivation by district in Eastern Region, Ghana and Lagos State, Nigeria. RESULTS: Internationally, commercial geospatial data resources were inversely related to all-cause mortality. This relationship was more pronounced when examining mortality due to communicable diseases. Commercial geospatial data resources for calculating patient travel times were more equitably distributed relative to health need than resources for characterising neighbourhoods or geocoding patient addresses. Countries such as South Africa have comparatively high commercial geospatial data availability despite high mortality, whilst countries such as South Korea have comparatively low data availability and low mortality. Sub-nationally, evidence was mixed as to whether geocoding success was lowest in more deprived districts. CONCLUSIONS: To our knowledge, this is the first global analysis of commercial geospatial data resources in relation to health outcomes. In countries such as South Africa where there is high mortality but also comparatively rich commercial geospatial data, these data resources are a potential resource for examining healthcare utilisation that requires further evaluation. In countries such as Sierra Leone where there is high mortality but minimal commercial geospatial data, alternative approaches such as open data use are needed in quantifying patient travel times, geocoding patient addresses, and characterising patients' neighbourhoods.

Telomere length increase after weight loss induced by bariatric surgery: results from a 10 year prospective study.

BACKGROUND/OBJECTIVES: Obesity contributes to telomere attrition. Studies focusing on short-term effects of weight loss have been unable to identify protection of telomere length. This study investigates long-term effects of pronounced weight loss induced by bariatric surgery on telomere length. SUBJECTS/METHODS: One hundred forty-two patients were recruited in a prospective, controlled intervention study, follow-up investigations were done after 10.46±1.48 years. A control group of normal weight participants was recruited and followed from 1995 to 2005 in the Bruneck Study. A total of 110 participants from each study was matched by age and sex to compare changes in telomere length. Quantitative PCR was used to determine telomere length. RESULTS: Telomere length increased significantly by 0.024±0.14 (P=0.047) in 142 bariatric patients within 10 years after surgery. The increase was different from telomere attrition in an age- and sex-matched cohort population of the Bruneck Study (-0.057±0.18; ß=0.08; P=0.003). Significant changes in telomere length disappeared after adjusting for baseline body mass index (BMI) because of general differences in BMI and telomere length between the two study populations (ß=0.07; P=0.06). Age was proportional to telomere length in matched bariatric patients (r=0.188; P=0.049) but inversely correlated with telomere length in participants of the Bruneck Study (r=-0.197; P=0.039). There was no association between percent BMI/excess weight loss and telomere attrition in bariatric patients. Baseline telomere length in bariatric patients was inversely associated with baseline plasma cholesterol and triglyceride concentrations. Telomere shortening was associated with lower high-density lipoprotein cholesterol and higher fasting glucose concentration at baseline in bariatric patients. CONCLUSIONS: Increases in relative telomere length were found after bariatric surgery in the long term, presumably due to amelioration of metabolic traits. This may overrule the influence of age and baseline telomere length and facilitate telomere protection in patients experiencing pronounced weight loss.

Dynamic inversion enables external magnets to concentrate ferromagnetic rods to a central target.

The ability to use magnets external to the body to focus therapy to deep tissue targets has remained an elusive goal in magnetic drug targeting. Researchers have hitherto been able to manipulate magnetic nanotherapeutics in vivo with nearby magnets but have remained unable to focus these therapies to targets deep within the body using magnets external to the body. One of the factors that has made focusing of therapy to central targets between magnets challenging is Samuel Earnshaw's theorem as applied to Maxwell's equations. These mathematical formulations imply that external static magnets cannot create a stable potential energy well between them. We posited that fast magnetic pulses could act on ferromagnetic rods before they could realign with the magnetic field. Mathematically, this is equivalent to reversing the sign of the potential energy term in Earnshaw's theorem, thus enabling a quasi-static stable trap between magnets. With in vitro experiments, we demonstrated that quick, shaped magnetic pulses can be successfully used to create inward pointing magnetic forces that, on average, enable external magnets to concentrate ferromagnetic rods to a central location.

Single particle tracking reveals biphasic transport during nanorod magnetophoresis through extracellular matrix.

Magnetic drug targeting has been proposed as a means of efficiently targeting drugs to tumors. However, the extracellular matrix (ECM) remains a significant barrier to long-range magnetophoretic transport through the tumor volume. While ensemble measurements of nanoparticle magnetophoresis have been reported, a single particle level understanding of magnetophoretic transport remains at large. We quantify nanorod magnetophoresis through ECM based on single particle observations. We find that smaller diameter particles achieve larger velocities through ECM despite experiencing smaller magnetic forces. Additionally, two interesting dynamics are elucidated. First, 18 nm diameter nanorods experience bimodal stick-slip motion through ECM during static field magnetophoresis, while similar bimodal transport is not observed for 55 nm nor 200 nm diameter nanorods. Second, smaller particles experience larger deviations in their orientation angle with respect to the magnetic field. This work elucidates important dynamics of nanoparticle transport through complex, porous biomaterials that may go unnoticed during ensemble measurements.

Evaluation of procalcitonin as a contribution to antimicrobial stewardship in SARS-CoV-2 infection: a retrospective cohort study.

It can be a diagnostic challenge to identify patients with coronavirus disease 2019 in whom antibiotics can be safely withheld. This study evaluated the effectiveness of a guideline implemented at Sheffield Teaching Hospitals NHS Foundation Trust that recommends withholding antibiotics in patients with low serum procalcitonin (PCT), defined as ≤0.25 ng/mL. Results showed reduced antibiotic consumption in patients with PCT ≤0.25 ng/mL with no increase in mortality, alongside a reduction in subsequent carbapenem prescriptions during admission. The results support the effectiveness of this guideline, and further research is recommended to identify the optimal cut-off value for PCT in this setting.

The nexus between improved water supply and water-borne diseases in urban areas in Africa: a scoping review.

Background: The sub-Saharan Africa has the fastest rate of urbanisation in the world. However, infrastructure growth in the region is slower than urbanisation rates, leading to inadequate provision and access to basic services such as piped safe drinking water. Lack of sufficient access to safe water has the potential to increase the burden of waterborne diseases among these urbanising populations. This scoping review assesses how the relationship between waterborne diseases and water sufficiency in Africa has been studied. Methods: In April 2020, we searched the Web of Science, PubMed, Embase and Google Scholar databases for studies of African cities that examined the effect of insufficient piped water supply on selected waterborne disease and syndromes (cholera, typhoid, diarrhea, amoebiasis, dysentery, gastroneteritis, cryptosporidium, cyclosporiasis, giardiasis, rotavirus). Only studies conducted in cities that had more than half a million residents in 2014 were included. Results: A total of 32 studies in 24 cities from 17 countries were included in the study. Most studies used case-control, cross-sectional individual or ecological level study designs. Proportion of the study population with access to piped water was the common water availability metrics measured while amounts consumed per capita or water interruptions were seldom used in assessing sufficient water supply. Diarrhea, cholera and typhoid were the major diseases or syndromes used to understand the association between health and water sufficiency in urban areas. There was weak correlation between the study designs used and the association with health outcomes and water sufficiency metrics. Very few studies looked at change in health outcomes and water sufficiency over time. Conclusion: Surveillance of health outcomes and the trends in piped water quantity and mode of access should be prioritised in urban areas in Africa in order to implement interventions towards reducing the burden associated with waterborne diseases and syndromes.

The use of objective digital matching to achieve an esthetic composite restoration.

OBJECTIVE: To investigate the ability to match composite restorations to teeth using digital imaging and CIE L*a*b* color differences. METHODS: Ten extracted human central incisors were used. Eleven discs of composite of differing shades were produced and mounted on white cardboard to create a customized shade guide (CSG). The CSG was photographed next to each of the ten teeth in a phantom head using a digital SLR camera. The images were analyzed, and color differences (deltaE) between the teeth and the shade discs were calculated using CIE L*a*b* values. Three cavities were then drilled into the labial surface of each tooth. Composite shades with the lowest three deltaE values were then used to restore the cavities. Ten observers evaluated the teeth under a standard D65 light source and recorded the best match. RESULTS: The majority of the observers selected the lowest deltaE in six out of the 10 teeth, and in a further two out of 10 teeth the second lowest deltaE was chosen. CONCLUSION: The lowest deltaE selected by objective color matching was agreed as the best match by observers. The high correlation between digital and visual color matching confirms the ability of digital camera and image analysis software to detect color differences.

Magnetic microkayaks: propulsion of microrods precessing near a surface by kilohertz frequency, rotating magnetic fields.

Surface-swimming nano- and micromotors hold significant potential for on-chip mixing, flow generation, sample manipulation, and microrobotics. Here we describe rotating microrods magnetized nearly orthogonally to their long axes. When actuated near a solid surface, these microrods demonstrate precessing motion, with rods describing a double cone similar to the motion of a kayaker's paddle. The precessing motion induces translation. At 1 kHz, these "microkayaks" move at translational velocities of ≈14 µm s-1 and generate advective flows up to 10 µm s-1.

Staining of in vivo subsurface degradation in dental composites with silver nitrate.

A previously reported technique for staining areas of degradation in dental composite restorations was evaluated in 51 removed restorations. The staining reagent was silver nitrate, which penetrated the degraded subsurface as ionic silver and was subsequently developed into colored deposits of metallic silver. Several artefacts were recognized that resulted in an apparent image of subsurface stain. Most importantly, the presence of a layer of adsorbed silver on the edge of the specimen exaggerated the extent of staining. In order for the true depth of stain to be determined, thin sections of the materials should first be examined with a stereomicroscope to distinguish any contribution from adsorbed silver on the specimen edge. With this regimen, no stain was present in 41% of the restorations, and in a further 30%, the depth of stain was less than 50 microns. In two composites, the depth of stain was greater than 900 microns, and in a number of specimens, localized stain was found in association with attrition scars. Energy-dispersive x-ray analysis indicated that the amount of silver present in the degraded layers was very small. Overall, the results indicated that the staining technique is useful in the study of composite degradation.

An association between the regular use of 3,4 methylenedioxy-methamphetamine (ecstasy) and excessive wear of the teeth.

AIMS: This study was established to determine if users of ecstasy had greater tooth wear than a comparison group of non-users. DESIGN: The study involved a direct comparison between two groups of young people gathered by a peer information network and divided by the response to the question "Do you take ecstasy?" SETTING: The information network was established at the Maryland Centre in Liverpool (UK). Besides offering advice on drug and sex-related problems this centre distributes free condoms and is therefore visited by many young people who would not consider themselves to have these problems. PARTICIPANTS: There were 30 users and 28 non-users with no significant difference in the gender ratio. Age was not recorded to maintain absolute confidentiality, but all the participants appeared to be of student age. MEASUREMENTS: Tooth wear was measured using the index of Smith & Knight. The social and drug-taking profile of the two groups was ascertained by questionnaire. FINDINGS: It was found that the mean (+/- STD) tooth wear score for the back teeth was 0.96 +/- 0.16 in the users compared with 0.12 +/- 0.08 for the comparison group. These values were significantly different (p < 0.001). The values for the front teeth were not significantly different. Many users were aware of clenching their teeth 12 or even 24 hours after taking the drug. CONCLUSION: Taking ecstasy results in an increased likelihood of tooth wear on the back teeth. This is likely to result from clenching the teeth in the acidic environment caused by carbonated (fizzy) drinks.

An investigation into the permeability of composite materials using silver nitrate.

A new effect of silver-nitrate staining on dental composites and unfilled polymers has been observed which may be useful in the study of polymer permeability. After extended storage in silver nitrate, the materials developed a layer of brown stain in the subsurface. The color was thought to be caused by the presence of finely divided silver precipitated in microcavities within the composite. Energy Dispersive Analysis by x-ray confirmed the presence of silver in the stained zone. The width and shade of staining varied in different materials. After 90 days, layers of different shades could be seen within the stained zone. The exact shade of the stain is thought to depend upon the size of the precipitated silver particles, which is directly related to the sizes of the microcavities.

The colors of silver with silver nitrate staining in dental materials.

Silver nitrate has been used as a stain to study the permeability, degradation, and marginal integrity of dental composite restorations. The reagent results in various colors in the composite or marginal interface. So that the cause of these colors could be investigated, this study compared the appearances of the stained layers by light and electron microscopy. The results indicated that the colors could be explained by the distribution of silver particles ranging from minute colloidal particles (20 nm) in the composite or dentin, to clusters of large particles (0.1-1 micron) in marginal interfaces. The colors can be explained by the absorption and scattering of light by these particles. At elevated temperatures, fused concretions of silver formed in the composite subsurface, resulting in direct reflection of incident light. The colors which appear with silver nitrate staining may indicate the size and distribution of microporosity in the material.

Surface permeability and degradation of dental composites resulting from oral temperature changes.

The surface changes in dental composites caused by thermal cycling and different temperatures were evaluated by use of silver nitrate to stain the surface layers. Rapid temperature change resulted in the formation of layers within the surface which may have resulted from microcracking. Slow rates of change increased the depth and rate of diffusion of silver nitrate. Determination of the temperature changes at the surface of a restoration in the mouth indicated that in vivo temperature change is more likely to increase the depth of diffusion of oral fluids than to cause microcracking of the surface.

Subsurface compression fatigue in seven dental composites.

OBJECTIVES: The purpose of this study was to evaluate subsurface fatigue in seven dental composites. METHODS: Cylindrical test pieces were subjected to 2000 compression cycles with a load of 120 N. The area of stained subsurface was measured, and subsequently, the specimens were examined by scanning electron microscopy. RESULTS: The greatest staining occurred in the composites with large quartz fillers, whereas there was little staining in the microfilled materials. Electron microscopy demonstrated very little evidence of cracks, suggesting that silver nitrate stained a network of crazes and microcracks in the subsurface. The pattern of staining indicated that the microcracks formed within the depth of the subsurface rather than by direct nucleation from the indenter. SIGNIFICANCE: The different patterns of subsurface damage occurring as a result of compression should be considered when studying the wear and degradation of these materials.

The silver sorption layer in dental composites: three year results.

OBJECTIVES: The purpose of this investigation was to observe the behaviour of a recently discovered silver sorption layer in seven dental composites for three years. METHODS: Rectangular block testpieces (3.0 x 2.5 x 2.5 mm) of seven resin composites were fabricated and the resin rich layer removed from one surface by grinding on silica carbide paper. The testpieces were immersed in aqueous AgNO3 (3 mol/l). After 26, 42, 90, 180, 360, 540, 720 and 1085 days, respectively, nine specimens of each material were removed to measure the depth of silver stain in the different composites. RESULTS: The depth of silver stain continued to increase at a rate proportional to (time)0.5. After three years, five homogeneous subsets [HS] were distinguished for the resin rich surface [HS1] Occlusin (stain depth = 45.6 microns); [HS2] Clearfil (117.8 microns), [HS3] Heliomolar (145.6 microns), Concise (148.8 microns), P-30 (168.9 microns); [HS4] Silux (243.3 microns); [HS5] Profile-TLC (446.7 microns). For the ground surface, the materials were in similar subsets but the depth of stain was less. Different coloured layers were seen within the sorption layer in some materials. SIGNIFICANCE: The linear relationship between the depth of stain and (time)0.5 indicate that the mechanism controlling the sorption is Case 1 (Fickian) diffusion. The different depths in the individual materials may indicate differences in the segmental mobility of the polymer chains and free space within the resin phase of the composites. If the silver sorption layer marks the extent of water penetration, then the results show different depth distributions for individual composites.

Measurement and analysis of clinical abrasion--a modified approach.

The abrasion of three posterior composites, after three years' clinical service, was measured by use of a calibrated stone step-wedge. The enamel exposure by each cusp was measured, so that the maximum and overall abrasion could be calculated. The results indicated uneven abrasion around the margin, signifying that local factors, acting by each cusp, had a significant effect on abrasion. This differs from the behavior of the earlier composites, where there was uniform abrasion around the margins. The overall abrasion had a nonparametric distribution, and frequency distribution diagrams proved to be the best way of comparing the performances of the individual materials.

The effect of thermal cycling on the fracture toughness of seven composite restorative materials.

Short-red chevron-notch samples of seven composite materials were thermal-cycled between 0 degrees C and 60 degrees C. The stress intensification factor, KIC, was found for four sample groups subjected to 10(1)-10(4) cycles, respectively. One group of uncycled samples was tested at the commencement of the investigation and another group after exposure to water for the equivalent time taken by 10(4) cycles (42 days). The KIC decreased for all materials, but the decrease after 10(4) cycles was not significantly different from that after storage in water for an equivalent period of time. These results indicate that, in the determination of KIC, the filler/matrix bond is of secondary importance to the presence of fillers. The effects of cyclic temperature changes likely to be encountered in the mouth are not a significant factor in reduction of the fracture strength of composite filling materials.

The occurrence of toothwear in users of Ecstasy (3,4-methylenedioxymethamphetamine).

UNLABELLED: Ecstasy users have reported that dry mouth, jaw tension and tooth grinding were common side effects of its use although the influence of these effects upon toothwear have not been previously investigated. OBJECTIVE: This study aimed to compare incisal and occlusal toothwear in Ecstasy users and a group of non-users of Ecstasy but users of other drugs. METHODS: Groups were established by a snowball peer information network from visitors to the "drop-in" Maryland Centre in Liverpool. Volunteers completed a questionnaire about social life, drug use and diet. Clinical examination for wear on the incisal edges and on canine tips was conducted with a mirror and probe, whereas occlusal wear was recorded in impressions and subsequently scored from stone replica casts. The degree of toothwear was scored according to the criteria of the Tooth Wear Index (Smith & Knight, Br Dent J 1984;157:16). RESULTS: Ecstasy users (n = 30) were compared with non-users (n = 28). Toothwear through the enamel into the underlying dentine occurred in 18 (60%) Ecstasy users but in only three (11%) non-users. The overall mean toothwear score in Ecstasy users was 0.63 compared with 0.16 in non-users (t = 4.34, P < 0.001). Dry mouth was reported by 93% of Ecstasy users whilst 89% stated that they clenched or ground their teeth after taking the drug. Tooth grinding commonly continued into the following morning. Carbonated (acidic) beverages were consumed by 93% of the users with a mean of three cans per "trip". CONCLUSION: The severity of toothwear and the number of teeth affected were greater in Ecstasy users than in a group of non-users. The occlusal surfaces were more commonly affected than the incisal, which may indicate jaw clenching rather than grinding as a feature of Ecstasy-induced muscle hyperactivity.

Wear patterns in two amalgams and three posterior composites after 5 years' clinical service.

OBJECTIVES: The purpose of this research was to evaluate the wear patterns of three posterior composites (Clearfil Posterior. Occlusin and P-30) and two amalgams (New True Dentalloy, Solila Nova) after 5 years' clinical service. METHODS: Marginal wear was measured using the stepwedge technique which determines the maximal marginal wear by any one cusp together with the mean marginal value. The overall maximum depth of wear, occurring at any site on the occlusal surface, was determined using an impression technique with epoxy models. RESULTS: The mean values (+/- standard deviations) for the overall maximum wear were: New True Dentalloy, 203 +/- 98 microns; Solila Nova, 200 +/- 96 microns; Clearfil Posterior, 252 +/- 141 microns; Occlusin, 324 +/- 189 microns; P-30, 380 +/- 273 microns. These values were significantly different (ANOVA F = 2.86 P = 0.05). There was no correlation between the marginal scores and the overall maximum depth of wear (P > 0.05). There was no correlation between the marginal scores and the overall maximum depth of wear (P > 0.05). With some restorations the maximum wear occurred at the margins, marginal ridges or cavity extensions rather than sites of occlusal contact. CONCLUSIONS: After 5 years' service the overall wear of three posterior composites exceeded that of two amalgams; however, for a number of restorations the difference was not significant. Marginal wear values cannot be used to predict the overall maximal depth of wear.