"Willingness to Pay": The Value Attributed to Program Location by Pulmonary Rehabilitation Participants

The "contingent valuation" method is used to quantify the value of services not available in traditional markets, by assessing the monetary value an individual ascribes to the benefit provided by an intervention. The aim of this study was to determine preferences for home or center-based pulmonary rehabilitation for participants with chronic obstructive pulmonary disease (COPD) using the "willingness to pay" (WTP) approach, the most widely used technique to elicit strengths of individual preferences. This is a secondary analysis of a randomized controlled equivalence trial comparing center-based and home-based pulmonary rehabilitation. At their final session, participants were asked to nominate the maximum that they would be willing to pay to undertake home-based pulmonary rehabilitation in preference to a center-based program. Regression analyses were used to investigate relationships between participant features and WTP values. Data were available for 141/163 eligible study participants (mean age 69 [SD 10] years, n = 82 female). In order to undertake home-based pulmonary rehabilitation in preference to a conventional center-based program, participants were willing to pay was mean $AUD176 (SD 255) (median $83 [IQR 0 to 244]). No significant difference for WTP values was observed between groups (p = 0.98). A WTP value above zero was related to home ownership (odds ratio [OR] 2.95, p = 0.02) and worse baseline SF-36 physical component score (OR 0.94, p = 0.02). This preliminary evidence for WTP in the context of pulmonary rehabilitation indicated the need for further exploration of preferences for treatment location in people with COPD to inform new models of service delivery.

The Impact of COPD Exacerbations in the Year Following Pulmonary Rehabilitation: Secondary Analysis of a Randomised Controlled Trial

Background

Pulmonary rehabilitation is an effective treatment for people with chronic obstructive pulmonary disease (COPD), but its benefits are poorly maintained. The aim of this study was to evaluate the impact of COPD exacerbations in the year following pulmonary rehabilitation on outcomes at 12 months.

Methods

This was a secondary analysis from a trial of home versus hospital-based rehabilitation in COPD, with 12 months of follow-up. Moderate and severe exacerbations were identified using administrative data (prescriptions) and hospital records (admissions) respectively. The impact of exacerbations at 12 months following pulmonary rehabilitation was evaluated for quality of life (Chronic Respiratory Questionnaire, CRQ), dyspnea (modified Medical Research Council, mMRC), exercise capacity (6-minute walk distance, 6MWD) and objectively measured physical activity (moderate-to-vigorous physical activity, MVPA).

Results

A total of 166 participants were included, with mean age (SD) 69 (9) years and forced expiratory volume in one second (FEV₁) 49 (19)% predicted. Moderate exacerbations occurred in 68% and severe exacerbations in 34% of participants. Experiencing a severe exacerbation was an independent predictor of worse 12-month outcomes for CRQ (total, fatigue and emotional function domains), mMRC, 6MWD and MVPA (all p<0.05). Participants who completed pulmonary rehabilitation were less likely to have a severe exacerbation (29% vs 48%, p=0.02). Severe exacerbations were more likely in those with worse baseline CRQ total (odds ratio 0.97, 95% CI 0.95 to 0.99) and FEV_1%predicted (0.98, 95% CI 0.96 to 0.99).

Conclusion

Severe exacerbations occur frequently following pulmonary rehabilitation and predict worse 12-month outcomes. Strategies to maintain the benefits of pulmonary rehabilitation should address exacerbation prevention and management.

Comparison of self-report and administrative data sources to capture health care resource use in people with chronic obstructive pulmonary disease following pulmonary rehabilitation

Background

The optimal method to collect accurate healthcare utilisation data in people with chronic obstructive pulmonary disease (COPD) is not well established. The aim of this study was to determine feasibility and compare self-report and administrative data sources to capture health care resource use in people with COPD for 12 months following pulmonary rehabilitation.

Methods

This is a secondary analysis of a randomised controlled equivalence trial comparing centre-based and home-based pulmonary rehabilitation. Healthcare utilisation data were collected for 12 months following pulmonary rehabilitation from self-report (monthly telephone questionnaires and diaries) and administrative sources (Medicare Benefits Schedule, medical records). Feasibility was assessed by the proportion of self-reports completed and accuracy was established using month-by-month and per participant comparison of self-reports with administrative data.

Results

Data were available for 145/163 eligible study participants (89%, mean age 69 (SD 9) years, mean forced expiratory volume in 1 s 51 (SD 19) % predicted; n = 83 male). For 1725 months where data collection was possible, 1160 (67%) telephone questionnaires and 331 (19%) diaries were completed. Accuracy of recall varied according to type of health care encounter and self-report method, being higher for telephone questionnaire report of emergency department presentation (Kappa 0.656, p < 0.001; specificity 99%, sensitivity 59%) and hospital admission (Kappa 0.669, p < 0.001; specificity 97%, sensitivity 68%) and lower for general practitioner (Kappa 0.400, p < 0.001; specificity 62%, sensitivity 78%) and medical specialist appointments (Kappa 0.458, p < 0.001; specificity 88%, sensitivity 58%). A wide variety of non-medical encounters were reported (allied health and nursing) which were not captured in administrative data.

Conclusion

For self-reported methods of healthcare utilisation in people with COPD following pulmonary rehabilitation, monthly telephone questionnaires were more frequently completed and more accurate than diaries. Compared to administrative records, self-reports of emergency department presentations and inpatient admissions were more accurate than for general practitioner and medical specialist appointments.

Trial registration

NCT01423227 at clinicaltrials.gov

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-020-05920-0.

Acceptability and validity of a home exercise diary used in home-based pulmonary rehabilitation: A secondary analysis of a randomised controlled trial

INTRODUCTION

Evaluating adherence to home-based pulmonary rehabilitation (PR) could be challenging due to lack of direct supervision and the complex nature of the rehabilitation model. To measure adherence to home-based PR in the HomeBase trial, participants were encouraged to work towards a goal of at least 30 min of whole-body exercise on most days of the week and report their participation using a home exercise diary.

OBJECTIVE

This project aimed to evaluate the acceptability and validity of the home exercise diary.

METHODS

Diary return and completion rates assessed acceptability of the home exercise diary. Home participants underwent physical activity (PA) monitoring using the Sensewear armband during the final week of an 8-week PR. The correlation between self-documented and objective daily exercise minutes was calculated. Objective exercise minutes were defined as bouts of ≥10 min spent in ≥ moderate PA. Differences in self-documented weekly exercise minutes between sufficiently active (≥7000 daily steps) and inactive participants were computed.

RESULTS

Diaries were returned by 92% of programme completers. Of those who returned diaries, 72% have completed exercise documentation. Fifteen programme completers underwent PA monitoring [mean age 69 (9) (SD) years, FEV₁ 55 (19) %predicted]. A moderate correlation was observed between self-documented and objective mean daily exercise minutes (r = .59, P = .02). Active participants [n = 6, 10 253 (1521) daily steps] documented more exercise (111 min) during week eight compared with inactive participants [n = 9, 2705 (1772) daily steps, P = .002].

CONCLUSION

The self-documented home exercise diary is an acceptable and valid method to reflect exercise participation during home-based PR.

Radiomics in Brain Tumor: Image Assessment, Quantitative Feature Descriptors, and Machine-Learning Approaches

Radiomics describes a broad set of computational methods that extract quantitative features from radiographic images. The resulting features can be used to inform imaging diagnosis, prognosis, and therapy response in oncology. However, major challenges remain for methodologic developments to optimize feature extraction and provide rapid information flow in clinical settings. Equally important, to be clinically useful, predictive radiomic properties must be clearly linked to meaningful biologic characteristics and qualitative imaging properties familiar to radiologists. Here we use a cross-disciplinary approach to highlight studies in radiomics. We review brain tumor radiologic studies (eg, imaging interpretation) through computational models (eg, computer vision and machine learning) that provide novel clinical insights. We outline current quantitative image feature extraction and prediction strategies with different levels of available clinical classes for supporting clinical decision-making. We further discuss machine-learning challenges and data opportunities to advance radiomic studies.

Combined PET/MRI: Global Warming-Summary Report of the 6th International Workshop on PET/MRI, March 27-29, 2017, Tübingen, Germany

The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tübingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.

Home-based pulmonary rehabilitation for people with COPD: A qualitative study reporting the patient perspective

This study aimed to document the perspective of patients with chronic obstructive pulmonary disease (COPD) who underwent home-based pulmonary rehabilitation (HBPR) in a clinical trial. In this qualitative study, open-ended questions explored participants’ views regarding HBPR. Thirteen semi-structured interviews were analysed using a thematic analysis approach. Major themes from interviews included the positive impact of HBPR on physical fitness, breathing and mood. Participants valued the flexibility and convenience of the programme. Participants also highlighted the importance of social support received, both from the physiotherapist over the phone and from family and friends who encouraged their participation. Reported challenges were difficulties in initiating exercise, lack of variety in training and physical incapability. While most participants supported the home setting, one participant would have preferred receiving supervised exercise training at the hospital. Participants also reported that HBPR had helped establish an exercise routine and improved their disease management. This study suggests that people with COPD valued the convenience of HBPR, experienced positive impacts on physical fitness and symptoms and felt supported by their community and programme staff. This highly structured HBPR model may be acceptable to some people with COPD as an alternative to centre-based pulmonary rehabilitation.

Combined PET/MRI: from Status Quo to Status Go. Summary Report of the Fifth International Workshop on PET/MR Imaging; February 15-19, 2016; Tübingen, Germany

This article provides a collaborative perspective of the discussions and conclusions from the fifth international workshop of combined positron emission tomorgraphy (PET)/magnetic resonance imaging (MRI) that was held in Tübingen, Germany, from February 15 to 19, 2016. Specifically, we summarise the second part of the workshop made up of invited presentations from active researchers in the field of PET/MRI and associated fields augmented by round table discussions and dialogue boards with specific topics. This year, this included practical advice as to possible approaches to moving PET/MRI into clinical routine, the use of PET/MRI in brain receptor imaging, in assessing cardiovascular diseases, cancer, infection, and inflammatory diseases. To address perceived challenges still remaining to innovatively integrate PET and MRI system technologies, a dedicated round table session brought together key representatives from industry and academia who were engaged with either the conceptualisation or early adoption of hybrid PET/MRI systems. Discussions during the workshop highlighted that emerging unique applications of PET/MRI such as the ability to provide multi-parametric quantitative and visual information which will enable not only overall disease detection but also disease characterisation would eventually be regarded as compelling arguments for the adoption of PET/MR. However, as indicated by previous workshops, evidence in favour of this observation is only growing slowly, mainly due to the ongoing inability to pool data cohorts from independent trials as well as different systems and sites. The participants emphasised that moving from status quo to status go entails the need to adopt standardised imaging procedures and the readiness to act together prospectively across multiple PET/MRI sites and vendors.

Home-based rehabilitation for COPD using minimal resources: a randomised, controlled equivalence trial

BACKGROUND

Pulmonary rehabilitation is a cornerstone of care for COPD but uptake of traditional centre-based programmes is poor. We assessed whether home-based pulmonary rehabilitation, delivered using minimal resources, had equivalent outcomes to centre-based pulmonary rehabilitation.

METHODS

A randomised controlled equivalence trial with 12 months follow-up. Participants with stable COPD were randomly assigned to receive 8 weeks of pulmonary rehabilitation by either the standard outpatient centre-based model, or a new home-based model including one home visit and seven once-weekly telephone calls from a physiotherapist. The primary outcome was change in 6 min walk distance (6MWD).

RESULTS

We enrolled 166 participants to receive centre-based rehabilitation (n=86) or home-based rehabilitation (n=80). Intention-to-treat analysis confirmed non-inferiority of home-based rehabilitation for 6MWD at end-rehabilitation and the confidence interval (CI) did not rule out superiority (mean difference favouring home group 18.6 m, 95% CI -3.3 to 40.7). At 12 months the CI did not exclude inferiority (-5.1 m, -29.2 to 18.9). Between-group differences for dyspnoea-related quality of life did not rule out superiority of home-based rehabilitation at programme completion (1.6 points, -0.3 to 3.5) and groups were equivalent at 12 months (0.05 points, -2.0 to 2.1). The per-protocol analysis showed the same pattern of findings. Neither group maintained postrehabilitation gains at 12 months.

CONCLUSIONS

This home-based pulmonary rehabilitation model, delivered with minimal resources, produced short-term clinical outcomes that were equivalent to centre-based pulmonary rehabilitation. Neither model was effective in maintaining gains at 12 months. Home-based pulmonary rehabilitation could be considered for people with COPD who cannot access centre-based pulmonary rehabilitation.

TRIAL REGISTRATION NUMBER

NCT01423227, clinicaltrials.gov.

Patient recollections of perioperative anaesthesia risks

There is widespread variation as to the method of presentation of informed anaesthetic consent with little empirical data on the nature of communication and how much information is retained. At a dedicated anaesthesia pre-admission clinic, 149 patients undergoing elective surgery under general anaesthesia were both verbally informed and shown written information about four major and three minor anaesthesia risks. The major risks were death, pneumonia, heart attack and stroke. The minor risks were dental damage, nausea and vomiting. On the day of scheduled surgery, retention of information about these anaesthetic risks was examined. Thirty-eight patients (26%) could not recall any anaesthesia risks, 55 patients (37%) could not recall any major risks and 126 patients (84%) could not recall any minor risks. Our findings indicate that patients should receive a second explanation on the day of surgery, even if informed consent was provided only two weeks earlier.

Convenient and Efficient Synthesis of a Lanthanide-Coordinated, Diethylene Triamine Pentaacetic Acid Labeled Biopolymer as an Assay for the Cholecystokinin B Receptor

To develop an assay for the cholecystokinin B receptor with an Eu(3+)-labeled cholecystokinin peptide via a diethylene triamine pentaacetic acid chelating linker, a commercial dianhydride diethylene triamine pentaacetic acid precursor was directly attached to the N-terminus of cholecystokinin peptides by a solid-phase synthesis method with a satisfactory yield and purity after reverse-phase high-performance liquid chromatography separation. Lanthanide was then coordinated to the peptide via a diethylene triamine pentaacetic acid bifunctional agent. This method is a useful approach to the large-scale synthesis of lanthanide(3+)-coordinated, diethylene triamine pentaacetic acid labeled biopolymers. This research provides not only a simple and convenient method for the preparation of lanthanide-based peptide ligand libraries but also possible lanthanide-based high-throughput screening of peptide receptors with a timeresolved fluorescence assay system. Five biopolymers were synthesized and characterized with high-resolution electrospray ionization in this study.

Exploring the views of second-year Foundation Programme doctors and their educational supervisors during a deanery-wide pilot Foundation Programme

AIM

To explore the views of second-year Foundation Programme doctors (F2s) and their educational supervisors taking part in a deanery-wide pilot Foundation Programme, in order to gain an understanding of their perceptions of the available learning experiences, support and supervision.

METHODS

20 semi-structured interviews were undertaken with randomly selected F2 doctors and educational supervisors participating in the deanery-wide pilot Foundation Programme.

RESULTS

F2 trainees received appropriate and sufficient support and supervision from a variety of sources during their placements; however, it was believed that additional training of educational supervisors was required. Trainees reported some problems with the perception of the role of an F2; further understanding of the purpose and role of the F2 programme is required at trust level. The portfolio was viewed positively as a record and a learning tool, but was thought to be too bureaucratic. Trainees believed that it was more beneficial to their careers to take part in a foundation programme as opposed to a traditional senior house officer post, but both trainees and educational supervisors expressed some concerns about the generic nature of some skills F2s were expected to acquire.

CONCLUSIONS

This evaluation has highlighted successful aspects of the Foundation Programme, particularly with regard to the level of support and range of experiences provided for trainees. Issues of concern to both trainees and educational supervisors have been identified, which require additional understanding.

The portfolio: how was it for you? Views of F2 doctors from the Mersey Deanery Foundation Pilot

A study was conducted between August 2004 and August 2005 to explore the experiences of Foundation year 2 (F2) trainees who used the learning portfolio on the Mersey Deanery pilot scheme. Seventy-three trainees (77%) reported receiving their portfolio during their induction. In their first four-month placement, 90 trainees (96%) completed the two case-based discussions, 80 (87%) the three mini clinical examinations and 92 (97%) the two direct observation of practical procedures. The number of trainees who felt there was an opportunity to make a record of and analyse clinical critical incidents and critical incidents related to professional behaviour was only 32 (35%) and 13 (15%) respectively. Free text responses suggested that trainees appreciate the portfolio but that an understanding of its content and purpose, particularly by educational supervisors, is paramount to its success.

Non-invasive in vivo determination of UVA efficacy of sunscreens using diffuse reflectance spectroscopy

BACKGROUND

Evaluation of sunscreen efficacy is most relevant when measured on the surface it is meant to protect, namely on human skin in vivo. Application of any material to the surface of the skin alters its optical properties. Diffuse reflectance spectroscopy (DRS) is a non-invasive technique to measure changes in the optical properties of the skin decoupled from its biological responses following sunscreen application.

METHODS

This study compared measurements of UVA efficacy of oxybenzone and avobenzone at different concentrations (0-5%) using DRS, human phototest and an in vitro technique. Twenty subjects were enrolled for each product measured by DRS and 10 different subjects were enrolled for each product measured by human phototest. Six areas 5 cm x 10 cm were outlined on each subject's back. DRS measurements were performed on four subsites within each area before and 20 min after sunscreen application. UVA efficacy for each concentration of product was calculated from the measured transmission spectrum of a given product convoluted with the spectrum of a Xenon light source adequately filtered to obtain the UVA spectrum from 320 to 400 nm and the erythema action spectrum. Phototesting was performed using the same light source and persistent pigment darkening as the biological endpoint. Measurements were made with sunscreen coverage of 2 mg/cm2. In vitro measurements were performed using an Optometrics instrument.

RESULTS

All three techniques showed a linear response between calculated UVA efficacy and product concentration.

CONCLUSIONS

This study showed that DRS is a rapid and reproducible method to calculate UVA efficacy of sunscreen materials and that its results correlate closely with those obtained by human phototesting.

Interrater reliability of the Glasgow Coma Scale scoring among nurses in sub-specialties of critical care

The Glasgow Coma Scale (GCS) is used as an assessment tool to measure the levels of consciousness and coma in patients. This research investigated the reliability of scoring the GCS among registered nurses (RNs) working in five different sub-specialty clinical areas of critical care; general intensive care, neurosurgical intensive care, coronary care, emergency room and post anaesthetic recovery room. Seven video recordings were made of six patients (one patient was recorded twice) having their level of neurological response assessed utilising the GCS. Seventy five RNs (15 from each sub-specialty) viewed each of the GCS assessments on the videotape and rated each patient on the scoring sheet provided. Analysis was performed for all RN subjects as a single group as well as separately for each of the five groups under investigation. The ratings for the first six videos were used to test interrater reliability and the scores from videotape four and seven (same patient) were used to calculate intrarater reliability. Based on comparison with expert scores, of the 75 participants, 38 responded correctly to eye opening responses; only 26 responded correctly to the motor response ratings. However, a better accuracy was achieved in the verbal response category with 67 participants responding correctly. Education qualifications and previous neurosurgical experience were statistically significant with regard to the nurses' accuracy of GCS assessment with p values of 0.004 and 0.043 respectively. The results were consistent with previously published studies demonstrating the motor response rating is most problematic in relation to rate accuracy.

Aging and effects of ultraviolet A exposure may be quantified by fluorescence excitation spectroscopy in vivo

The fluorescence properties of skin chromophores such as tryptophan and collagen cross-links might be useful markers of aging and photoaging. As the fluorescence of pepsin-digestible collagen cross-links was found to increase with aging and decrease with photoaging we investigated the characteristics of this dependence. In vivo fluorescence excitation spectra (emission at 380 nm) of SKH hairless mouse model skin are characterized by two bands centered near 295 nm and 335 nm due, respectively, to epidermal tryptophan moieties and pepsin-digestible collagen cross-links. Several groups of hairless mice were followed over a period of 18 mo to document changes in skin fluorescence with aging. Other groups of animals were exposed to either broad band or narrowband ultraviolet A radiation to determine the effects of ultraviolet A exposure on the fluorescence of the dermal collagen cross-links and to determine an action spectrum for the induced changes. We also found that the intensity of pepsin-digestible collagen cross-links in vivo increases linearly with age and that the fluorescence of epidermal tryptophan decreases linearly with age. We found that the fluorescence of pepsin-digestible collagen cross-links decreases immediately following exposure to ultraviolet A whereas epidermal tryptophan fluorescence increases. Both changes were dose dependent but the increase in tryptophan fluorescence occurred exclusively in young animals (2--6 mo old). We found that the ultraviolet-induced fluorescence decrease of pepsin-digestible collagen cross-links is wavelength specific. The action spectrum for the ultraviolet A effect on the in vivo fluorescence of pepsin-digestible collagen cross-links shows a distinct maximum at 335 nm that corresponds to the maximum in the fluorescence excitation spectrum due to pepsin-digestible collagen cross-links. Our results seem to indicate that in vivo fluorescence of epidermal tryptophan moieties and collagen cross-links in the dermal matrix may serve as markers for skin aging, for photoaging, and for immediate assessment of exposure to ultraviolet A radiation.

A rapid method to detect dried saliva stains swabbed from human skin using fluorescence spectroscopy

Saliva on skin is important in forensic trace evidence. If areas where saliva is present can be outlined, this may lead to DNA analysis and identification. This study describes a rapid and non-destructive method to detect dried saliva on the surface of the skin by fluorescence spectroscopy. Eighty-two volunteers deposited samples of their own saliva on the skin of their ventral forearm. A control sample of water was deposited at three different sites on the contralateral arm. Saliva and water control were then allowed to air-dry. Swab samples were taken from dried saliva and control sites and were dissolved in 0.1M KCl solution. Emission spectra were obtained from the solution and were characterized by a principal maximum at 345-355nm with excitation at 282nm. The fluorescence emission intensity was greater than background readings obtained from the control swab site in 80 of 82 volunteers (approximately 97.6%). The fluorescence profile of saliva samples were similar to those obtained from aqueous samples of pure amylase and tryptophan, an endogenous fluorophore in alpha-amylase. The presence of an emission peak at 345-355nm with excitation at 282nm could provide a strong presumptive indication of saliva deposition.

Fluorescence excitation spectroscopy provides information about human skin in vivo

Fluorescence spectroscopy of human skin has the potential to provide useful morphologic and biochemical information. The endogenous fluorescence of human skin has been investigated in vivo on normal human volunteers as well as on patients with psoriasis and it was found that characteristic bands can be identified in the fluorescence spectra that are associated with specific skin fluorophores. One epidermal band (295 nm excitation, attributed to tryptophan) and two dermal bands (335 and 370 nm excitation, attributed to collagen cross-links) were consistently present in all fluorescence spectra. In addition, the fluorescence spectra obtained from lesions and nonlesional sites of psoriatic patients differed from those obtained from healthy volunteers and the hyperproliferative state of the lesions was characterized by a significantly larger signal at 295 nm excitation. These results indicate that fluorescence spectroscopy is a promising technique for the investigation of human skin in vivo.

Endogenous skin fluorescence is a good marker for objective evaluation of comedolysis

OBJECTIVE

evaluation of comedone lesions, especially in vivo, remains a challenge. We have used the rhino mouse model in combination with topical application of all-trans retinoic acid as a comedolytic agent, to investigate the potential of fluorescence spectroscopy as a noninvasive technique in the assessment of noninflammatory acne. The results indicate that there is a strong correlation between the fluorescence excitation spectral features assessed in vivo, and the histologic changes identified, particularly the size of the utriculi as well as the dermal and epidermal thickness. We conclude that fluorescence excitation spectroscopy represents a promising novel and useful tool in the quantitative evaluation of the pseudocomedones and could also be used for the rapid and noninvasive assessment of comedolysis induced by the application of pharmacologic agents such as retinoids.

Microfine zinc oxide is a superior sunscreen ingredient to microfine titanium dioxide

BACKGROUND

Microfine zinc oxide and microfine titanium dioxide are particulate sunscreen ingredients that absorb broad-spectrum ultraviolet (UV) irradiation.

OBJECTIVE

We compare microfine zinc oxide and microfine titanium dioxide for their abilities to attenuate UVA radiation and their relative whiteness in cosmetic formulations.

METHODS

UVA attenuation was measured by diffuse reflectance spectroscopy on normal human skin in vivo. Whiteness was determined by reflectance density of dried coatings on a black background of the two particulates at varying concentrations.

RESULTS

Microfine zinc oxide demonstrates superior protection compared to microfine titanium dioxide in the UV spectrum between 340 and 380 nm. Microfine zinc oxide is less white than titanium dioxide at all concentrations.

CONCLUSION

Microfine zinc oxide is superior to microfine titanium dioxide as a sunscreen ingredient. It is more protective against long-wave UVA and is less white at a given concentration.

Spectroscopic determination of skin viability. A predictor of postmortem interval

We have demonstrated that skin viability decreases at a measurable rate following death in an animal model. The decreased skin viability was measured by fluorescein diacetate and ethidium bromide using fluorescence emission spectroscopy. There is significant decrease of the fluorescence intensity of the fluorescein diacetate assay between the 1-4 h, the 6-24 h, and the >40 h time points postmortem. For times between 6-24 h and >40 h postmortem the ethidium bromide assay showed consistent and significant increases in signal. The fluorescence measurements in this study showed that under the experimental conditions the time of death could be determined for <4, 6-24, and >40 hapotmotrem. The application of these assays in the field will require further study of the environmental factors.