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Sugar-rich diets and poor dental hygiene promote the formation of a biofilm (plaque) that strongly adheres to the dental enamel surface and fosters the evolution of aciduric bacteria. The acid contributes to demineralization of the exterior tooth enamel, which accelerates after the pH drops below a critical value (∼5.5) for extended time periods resulting in the need for restorative procedures. Preventative techniques to alert the dentist and caries-susceptible patients regarding vulnerability to dental decay require a clinical measure of plaque activity. Therefore, there is a need to evaluate the acid production capability of plaque deposits in the pits and fissures of occlusal and interproximal regions. A ratiometric fluorescence pH-sensing device has been developed using an FDA-approved dye and LED excitation. Fluorescein spectral profiles were collected using a spectrometer and analyzed with a spectral unmixing algorithm for calibration over the pH range of 4.5 to 7. An in vivo pilot study on human subjects was performed using a sucrose rinse to accelerate bacterial metabolism and to measure the time-dependent drop in pH. The optical system is relatively immune to confounding factors such as photobleaching, dye concentration, and variation in excitation intensity associated with earlier dye-based pH measurement techniques.

PURPOSE: To ameliorate tradeoffs between a fixed spatial resolution and signal-to-noise ratio (SNR) for hyperpolarized (13)C MRI. METHODS: In MRI, SNR is proportional to voxel volume but retrospective downsampling or voxel averaging only improves SNR by the square root of voxel size. This can be exploited with a metabolite-selective imaging approach that independently encodes each compound, yielding high-resolution images for the injected substrate and coarser resolution images for downstream metabolites, while maintaining adequate SNR for each. To assess the efficacy of this approach, hyperpolarized [1-(13)C]pyruvate data were acquired in healthy Sprague-Dawley rats (n = 4) and in two healthy human subjects. RESULTS: Compared with a constant resolution acquisition, variable-resolution data sets showed improved detectability of metabolites in pre-clinical renal studies with a 3.5-fold, 8.7-fold, and 6.0-fold increase in SNR for lactate, alanine, and bicarbonate data, respectively. Variable-resolution data sets from healthy human subjects showed cardiac structure and neuro-vasculature in the higher resolution pyruvate images (6.0 × 6.0 mm(2) for cardiac and 7.5 × 7.5 mm(2) for brain) that would otherwise be missed due to partial-volume effects and illustrates the level of detail that can be achieved with hyperpolarized substrates in a clinical setting. CONCLUSION: We developed a variable-resolution strategy for hyperpolarized (13)C MRI using metabolite-selective imaging and demonstrated that it mitigates tradeoffs between a fixed spatial resolution and SNR for hyperpolarized substrates, providing both high resolution pyruvate and coarse resolution metabolite data sets in a single exam. This technique shows promise to improve future studies by maximizing metabolite SNR while minimizing partial-volume effects from the injected substrate.

Background and purpose Nurse practitioners (NPs) frequently treat acute conditions presenting in children and adolescents in the outpatient setting. No evidence-based guidance exists pertaining to the treatment of concussion with medications. The purpose of this study was to examine recommendations by NPs for pharmacotherapy of acute symptoms for adolescent concussion. Methods This is a secondary analysis of data from a web-based census survey of all licensed NPs in Oregon and Washington State, where they practice as independent providers with prescriptive authority. Based on a standardized adolescent patient scenario video, NPs were asked to indicate prescription or nonprescription medication recommendations for concussion symptoms. Open-ended descriptions of medication recommendations were coded, summarized, and described. Conclusions In narrative text, 78.4% of the 991 respondents recommended at least one type of prescription or nonprescription medication. Prescription medications (recommended by 17.2%) included antiemetics and antimigraine medications; nonprescription medications (recommended by 75.5%) included nonsteroidal anti-inflammatory drugs, over-the-counter pain relievers, and herbal medications. Pharmacotherapy recommendations varied by NP practice setting and rurality. Implications for practice Nurse practitioners have full prescriptive authority in many states. No guidelines inform medication use in managing acute concussion symptoms, yet many providers recommend their use.

Introduction Nurse practitioners (NPs) are authorized to manage concussion recovery. Common adolescent activities, like driving, are omitted from guidelines. We investigated NP driving guidance and its clinical basis for restriction or limitation following adolescent concussion. Method NPs completed a web-based questionnaire after viewing a scripted video scenario of an adolescent describing symptoms of concussion occurring 72 hours prior. Driving recommendations were collected using an open-ended query, then coded and categorized by type, characteristic, and basis. Results 1,051 (20%) responded to the question of interest. The majority (93.8%) provided driving recommendations: 32.6% based on time, 49.8% based on symptoms, and 28.5% based on health care utilization. 5.3% mentioned fatigue and sleep symptoms. 1% advised use of a standardized assessment tool. Discussion Symptomatology, examination, and time were key factors in clinical decision-making for post-concussion driving, rather than use of standardized tools. Persistent symptoms that can impact driving, such as sleep and visual disturbances, may warrant consideration.

We have developed a new tool to measure the acid production by plaque oral bacteria. Many species of oral bacteria metabolize sugars in food and produce organic acids that demineralize the dental enamel leading to the formation of cavities. Measuring the acidity level before and after a sugar rinse can indicate the susceptibility of an individual to tooth decay and location of active caries. In a case study on two subjects, a non-contact optics-based pH device was able to track pH before and after a sugar rinse. The fiber optic probe measures acidity level in difficult to access dental locations such as occlusal pits and fissures based on changes in the spectral fluorescence profile of fluorescein (FL) dye. Fiber coupled 420 nm LED excites 200uM aqueous FL solution in the mouth. The fluorescence spectrum in 450-650 nm range is obtained using an adjacent fiber optic cable coupled to a spectrometer. Chemometric analysis of endmember dianion and anion species using least-square fitting is performed to determine the pH of the FL absorbed into the extracellular region of the oral biofilm. Other unwanted noise, like background light and auto-fluorescence in the range of 450-650 nm is removed before calculating biofilm pH. Using this device in a darkened room on two subjects, we were able to measure resting pH (before a sugar rinse) and track time dependent change in pH (after a sugar rinse) in the range of pH 4-7 paving the way for first clinical optical pH measurement in the mouth.

Undetected caries can lead to painful cavities and surgical restorations. Lack of proper detection tools makes caries prevention dependent on dentist's expertise and presents obstacles in oral health monitoring. To overcome this problem, we have developed a new approach to predict early stages of enamel demineralization caused by oral bacteria. These bacteria metabolize sugars in our food and produce organic acids that lead to cavities. Measuring the acidity level can help predict early stages of tooth decay. pH paper or pH electrodes can be used to monitor acidity, but neither are able to track pH levels in all dental locations. Our device, DpOW, is a noncontact optics-based pH device that uses changes in the spectral fluorescence of FDA allowed fluorescein dye to measure acidity levels in difficult to access dental locations such as occlusal fissures. A prototype has been tested over a wide pH range (7.12 to 3.89) and shown to track the change in pH with 0.94 correlation coefficient.

A pH measurement of oral biofilms is helpful for monitoring the impact of acidogenic bacteria in the caries process. Demineralization of dental enamel is closely related to the time dependent pH of human plaque. Therefore, providing a means to easily measure the local pH of biofilms is a useful clinical diagnostic in the arsenal of caries prevention tools. Optical measurement methods of plaque metabolism can use intrinsic fluorescence or extrinsic fluorescence from added dyes. Autofluorescence spectral features of human oral biofilms at green (500 nm) and red (634 nm) fluorescence wavelengths using 405 nm excitation did not demonstrate a spectral or intensity shift between neutral and acidic conditions. Chlorin e6, an ingredient in chlorophyllin food supplement, exhibited a spectral and intensity shift of fluorescence emission in buffered solutions, but this quantitative pH-dependence was not transferable to a human plaque environment. Finally, a ratiometric quantitative pH measure was achieved by exciting (405 nm laser) a mixture of two dyes, fluorescein and rhodamine B. This two-dye mixture produced two strong fluorescent bands centered at 515 nm (fluorescein) and 580 nm (rhodamine B), where the 515 nm band was pH sensitive and the 580 nm band served as a pH insensitive reference. This dual-dye fluorescence ratio exhibited a linear response over pH 7 to 5 in human oral biofilms during a sugar challenge. We have explored methods to use non-contact, optical measures of local acidity levels in difficult to access dental locations such as occlusal fissures using various pH sensitive fluorescent dye systems.

Dentists rely on visual examination for diagnosing tooth decay which lacks quantification. To predict enamel demineralization, pH is spectrally mapped using fluorescence. To monitor enamel healing, lesion extent is measured using infrared endoscopic imaging.

Sugar-rich diets and poor dental hygiene promote the formation of a biofilm (plaque) that strongly adheres to the dental enamel surface and fosters the evolution of aciduric bacteria. The acid contributes to demineralization of the exterior tooth enamel, which accelerates after the pH drops below a critical value (∼5.5) for extended time periods resulting in the need for restorative procedures. Preventative techniques to alert the dentist and caries-susceptible patients regarding vulnerability to dental decay require a clinical measure of plaque activity. Therefore, there is a need to evaluate the acid production capability of plaque deposits in the pits and fissures of occlusal and interproximal regions. A ratiometric fluorescence pH-sensing device has been developed using an FDA-approved dye and LED excitation. Fluorescein spectral profiles were collected using a spectrometer and analyzed with a spectral unmixing algorithm for calibration over the pH range of 4.5 to 7. An in vivo pilot study on human subjects was performed using a sucrose rinse to accelerate bacterial metabolism and to measure the time-dependent drop in pH. The optical system is relatively immune to confounding factors such as photobleaching, dye concentration, and variation in excitation intensity associated with earlier dye-based pH measurement techniques.