Cryopreservation of the collector urchin embryo, Tripneustes gratilla

The collector urchin, Tripneustes gratilla, is an ecologically important member of the grazing community of Hawai'i's coral reefs. Beyond its ability to maintain balance between native seaweeds and corals, T. gratilla has also been used as a food source and a biocontrol agent against alien invasive algae species. Due to overexploitation, habitat degradation, and other stressors, their populations face local extirpation. However, artificial reproductive techniques, such as cryopreservation, could provide more consistent seedstock throughout the year to supplement aquaculture efforts. Although the sperm and larvae of temperate urchins have been successfully cryopreserved, tropical urchins living on coral reefs have not. Here, we investigated the urchin embryos' tolerance to various cryoprotectants and cooling rates to develop a cryopreservation protocol for T. gratilla. We found that using 1 M Me2SO with a cooling rate of 9.7 °C/min on gastrula stage embryos produced the best results with survival rates of up to 85.5% and up to 50.8% maturation to the 4-arm echinopluteus stage, assessed three days after thawing. Continued research could see cryopreservation added to the repertoire of artificial reproductive techniques for T. gratilla, thereby assisting in the preservation of this ecologically important urchin, all while augmenting aquaculture efforts that contribute to coral reef restoration.

Conduction-Dominated Cryomesh for Organism Vitrification

Vitrification-based cryopreservation is a promising approach to achieving long-term storage of biological systems for maintaining biodiversity, healthcare, and sustainable food production. Using the "cryomesh" system achieves rapid cooling and rewarming of biomaterials, but further improvement in cooling rates is needed to increase biosystem viability and the ability to cryopreserve new biosystems. Improved cooling rates and viability are possible by enabling conductive cooling through cryomesh. Conduction-dominated cryomesh improves cooling rates from twofold to tenfold (i.e., 0.24 to 1.2 × 105  °C min-1 ) in a variety of biosystems. Higher thermal conductivity, smaller mesh wire diameter and pore size, and minimizing the nitrogen vapor barrier (e.g., vertical plunging in liquid nitrogen) are key parameters to achieving improved vitrification. Conduction-dominated cryomesh successfully vitrifies coral larvae, Drosophila embryos, and zebrafish embryos with improved outcomes. Not only a theoretical foundation for improved vitrification in µm to mm biosystems but also the capability to scale up for biorepositories and/or agricultural, aquaculture, or scientific use are demonstrated.

Failure Mode and Effects Analysis Prior to the Introduction of AI Generated GTVs for Brain Metastases in the Clinical Workflow

PURPOSE/OBJECTIVE(S)

AI autosegmentation of organs-at-risk (OARs) is common practice at many radiotherapy clinics. Despite the abundance of gross tumor volume (GTV) autosegmentation algorithms, adoption in clinical care has been slow due to the high risk associated with errors in GTV delineation. Here we present a failure mode and effects analysis (FMEA) to evaluate the risk associated with introducing AI derived GTVs in patients treated with stereotactic radiosurgery (SRS).

MATERIALS/METHODS

An AI GTV autosegmentation algorithm for brain metastases was developed in-house based on a V-Net 3D CNN. Registered CT and MR images and a contour of the brain are input into the software and all identified lesions are returned in a DICOM-RT structure set. Following algorithm evaluation, a workflow was developed to enable AI GTV autosegmentation to be introduced clinically for every SRS patient. The following steps were added to existing procedures: 1) workflow to send CT/MR and brain structure to external server, 2) autosegmentation run on the server, 3) AI GTV structures with a standard nomenclature added to existing OAR structure set, and 4) MD review, editing, and approval of AI GTVs. After successfully completing the physics evaluation testing of the new process, we formed a team of 10 faculty and staff including physicists, residents, physicians, and planners to perform the FMEA prior to clinical implementation. The team met to map the process, identify potential failure modes, and score their frequency of occurrence, severity, and detectability. A 3-point scale (1, 3, or 5) was used to simplify the scoring process. Occurrence was defined as rare, sometimes, or often; severity as low, medium, or high; and detectability as obvious, possible, or challenging. The risk probability numbers (RPNs) were calculated and the steps in the process with the highest RPNs were flagged for further discussion.

RESULTS

The FMEA team completed their process map and analysis primarily in 4 meetings. The process map began with acquisition of the patients CT simulation scan and ended with physician approval of final volumes for treatment planning. We identified 17 process steps and 72 possible failure modes, of which 26 were associated with the new workflow. Eighteen failure modes had an RPN greater than 30 (highest risk score in at least one category) and were flagged to assess mitigation strategies. Five were unique to the new AI GTV workflow and mitigation strategies will be designed prior to clinical use. Those involved risks related to inaccurate AI GTV contours, false positives, and an incomplete review stemming from over-reliance by team members on AI.

CONCLUSION

AI is increasingly being employed at every step of radiotherapy to automate and streamline processes. The FMEA analysis resulted in the identification of the riskiest parts of using AI GTV autosegmentation. This can be an effective tool in the development of checks to ensure that GTV autosegmentation methods can be safely introduced in support of patient care.

Cryopreservation Cooling Rate Impacts Post-Thaw Sperm Motility and Survival in Litoria booroolongensis

The cryopreservation and storage of gametes (biobanking) can provide a long-term, low-cost option for the preservation of population genetic diversity and is particularly impactful when applied to manage selective breeding within conservation breeding programs (CBPs). This study aimed to develop a sperm cryopreservation protocol for the critically endangered Booroolong frog (Litoria booroolongensis) to capture founder genetics within the recently established (est. 2019) CBP for this species. Hormone-induced sperm release was achieved using established protocols, and spermic urine samples were collected over a 6-h period. Pooled spermic urine samples (n = 3 males) were divided equally between two cryoprotectant (CPA) treatments and diluted by 1:5 (sperm:CPA) with either 15% (v/v) dimethyl sulfoxide + 1% (w/v) sucrose in simplified amphibian Ringer's (SAR; CPAA) or 10% (v/v) dimethylformamide + 10% (w/v) trehalose dihydrate in SAR (CPAB). The samples were cryopreserved in 0.25 mL straws using either a programmable freezer (FrA) or an adapted dry shipper method (FrB). The thawed samples were activated via dilution in water and assessed for viability and motility using both manual assessment and computer-assisted sperm analysis (CASA; 0 h, 0.5 h post-thaw). Upon activation, the survival and recovery of motility (total motility, forward progression and velocity) of cryopreserved sperm suspensions were higher for sperm preserved using FrB than FrA, regardless of CPA composition. This work supports our long-term goal to pioneer the integration of biobanked cryopreserved sperm with population genetic management to maximize restoration program outcomes for Australian amphibian species.

Cryopreservation and revival of Hawaiian stony corals using isochoric vitrification

Corals are under siege by both local and global threats, creating a worldwide reef crisis. Cryopreservation is an important intervention measure and a vital component of the modern coral conservation toolkit, but preservation techniques are currently limited to sensitive reproductive materials that can only be obtained a few nights per year during spawning. Here, we report the successful cryopreservation and revival of cm-scale coral fragments via mL-scale isochoric vitrification. We demonstrate coral viability at 24 h post-thaw using a calibrated oxygen-uptake respirometry technique, and further show that the method can be applied in a passive, electronics-free configuration. Finally, we detail a complete prototype coral cryopreservation pipeline, which provides a platform for essential next steps in modulating post-thaw stress and initiating long-term growth. These findings pave the way towards an approach that can be rapidly deployed around the world to secure the biological genetic diversity of our vanishing coral reefs.

Tank fouling community enhances coral microfragment growth

Anthropogenic stressors threaten reefs worldwide and natural in situ coral reproduction may be inadequate to meet this challenge. Land-based culture can provide increased coral growth, especially with microfragments. We tested whether culture methods using different algal fouling communities could improve the growth and health metrics of microfragments of the Hawaiian coral, Porites compressa. Culture method fouling communities were: (1) similar to a reef environment (Mini Reef); (2) clean tanks managed to promote crustose coralline algae (Clean Start); and (3) tanks curated beforehand with poorly-competing algae (Green Film) assessed in winter and summer months. The Green Film method during the winter produced the fastest microfragment mean growth at 28 days until the first row of new polyps developed, and also the highest tank and plate metric health scores. Time efficient, standardized methods for land-based culture designed to maximize growth and production of coral fragments will contribute considerably to the success of large-scale restoration efforts.

Pharmacologic inhibition of NLRP3 reduces the levels of α-synuclein and protects dopaminergic neurons in a model of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is characterized by a progressive degeneration of dopaminergic neurons, which leads to irreversible loss of peripheral motor functions. Death of dopaminergic neurons induces an inflammatory response in microglial cells, which further exacerbates neuronal loss. Reducing inflammation is expected to ameliorate neuronal loss and arrest motor dysfunctions. Because of the contribution of the NLRP3 inflammasome to the inflammatory response in PD, we targeted NLRP3 using the specific inhibitor OLT1177^®.

METHODS

We evaluated the effectiveness of OLT1177^® in reducing the inflammatory response in an MPTP neurotoxic model of PD. Using a combination of in vitro and in vivo studies, we analyzed the effects of NLRP3 inhibition on pro-inflammatory markers in the brain, α-synuclein aggregation, and dopaminergic neuron survival. We also determined the effects of OLT1177^® on locomotor deficits associated with MPTP and brain penetrance.

RESULTS

Treatment with OLT1177^® prevented the loss of motor function, reduced the levels of α-synuclein, modulated pro-inflammatory markers in the nigrostriatal areas of the brain, and protected dopaminergic neurons from degeneration in the MPTP model of PD. We also demonstrated that OLT1177^® crosses the blood-brain barrier and reaches therapeutic concentrations in the brain.

CONCLUSIONS

These data suggest that targeting the NLRP3 inflammasome by OLT1177^® may be a safe and novel therapeutic approach to arrest neuroinflammation and protect against neurological deficits of Parkinson's disease in humans.

45 INTERPROFESSIONAL EDUCATION AND COLLABORATIVE PRACTICE IN FRAIL OLDER PERSONS’ CARE

Background

Frail older adults present with complex care needs. Inter-Professional Education (IPE) is a means of creating a practice-ready workforce to improve patient safety and healthcare outcomes. A Steering Group was established comprised of acute and community clinicians, members of the Health Service Executive, service user, students and members of all Schools in the College of Medicine and Health in an Irish University (Medicine, Nursing and Midwifery, Pharmacy, Public Health, Clinical Therapies and Dentistry) to evaluate the effectiveness of IPE. A workshop dedicated to the management of frail older adults occurred for multidisciplinary healthcare students as part of a suite of three IPE workshops.

Methods

The validated ‘Interprofessional Collaborative Competencies Attainment Survey’ (ICCAS) evaluated student views of IPE pre- & post-workshop. This workshop involved a case-based study and facilitated discussion with involvement of frail older adult service users. One service user was in a rehabilitation unit post hospital admission, the other was living well at home. Their participation occurred using an online platform, supported by a consultant geriatrician in the rehabilitation unit and a relative for the home-based service user.

Results

Student scores on the six subscales of the ICCAS (communication, collaboration, roles and responsibilities, collaborative patient-centred approach, conflict management and team functioning) were compared. Scores in all categories achieved statistically significant increases after completion of the IPE workshop. The greatest positive change was observed in collaborative patient-centred approach with pre-workshop scores increasing from a mean of 2.61 to 4.25 (p<0.05).

Conclusion

This initiative explored the inclusion of a frail older adult workshop in the higher education setting. Older adults had an opportunity to share their lived experiences. Evaluation of this IPE initiative will inform future IPE activities to be incorporated into undergraduate education programmes. Similar IPE models can be replicated nationally to enable and enhance team-based working and integrated care.

Reproductive plasticity of Hawaiian Montipora corals following thermal stress

Ocean warming, fueled by climate change, is the primary cause of coral bleaching events which are predicted to increase in frequency. Bleaching is generally damaging to coral reproduction, can be exacerbated by concomitant stressors like ultraviolet radiation (UVR), and can have lasting impacts to successful reproduction and potential adaptation. We compared morphological and physiological reproductive metrics (e.g., sperm motility, mitochondrial membrane integrity, egg volume, gametes per bundle, and fertilization and settlement success) of two Hawaiian Montipora corals after consecutive bleaching events in 2014 and 2015. Between the species, sperm motility and mitochondrial membrane potential had the most disparate results. Percent sperm motility in M. capitata, which declined to ~ 40% during bleaching from a normal range of 70-90%, was still less than 50% motile in 2017 and 2018 and had not fully recovered in 2019 (63% motile). By contrast, percent sperm motility in Montipora spp. was 86% and 74% in 2018 and 2019, respectively. This reduction in motility was correlated with damage to mitochondria in M. capitata but not Montipora spp. A major difference between these species is the physiological foundation of their UVR protection, and we hypothesize that UVR protective mechanisms inherent in Montipora spp. mitigate this reproductive damage.

Freezing on the beach: A robust coral sperm cryopreservation design

Cryopreservation of coral sperm requires reliable, travel-ready, inexpensive hardware. To this end, we developed and tested a robust, second-generation, conduction-based cryovial cooling rack assembled from 3D-printed and commercially available parts. Cooling rates from -10 to -80 °C were found to be repeatable at -22.9 ± 1.9 (rate ± SD) °C/min for 1-mL samples and -35.4 ± 3.3 °C/min for 0.5-mL samples. This represents an improvement on the variability of cooling rates in an older design, which was found to be -31.8 ± 7.1 °C/min for 1-mL samples. Design files and a manual were produced to encourage widespread use and the development of derivative designs.

New directions in assisted breeding techniques for fish conservation

Fish populations continue to decline globally, signalling the need for new initiatives to conserve endangered species. Over the past two decades, with advances in our understanding of fish germ line biology, new exsitu management strategies for fish genetics and reproduction have focused on the use of germ line cells. The development of germ cell transplantation techniques for the purposes of propagating fish species, most commonly farmed species such as salmonids, has been gaining interest among conservation scientists as a means of regenerating endangered species. Previously, exsitu conservation methods in fish have been restricted to the cryopreservation of gametes or maintaining captive breeding colonies, both of which face significant challenges that have restricted their widespread implementation. However, advances in germ cell transplantation techniques have made its application in endangered species tangible. Using this approach, it is possible to preserve the genetics of fish species at any stage in their reproductive cycle regardless of sexual maturity or the limitations of brief annual spawning periods. Combining cryopreservation and germ cell transplantation will greatly expand our ability to preserve functional genetic samples from threatened species, to secure fish biodiversity and to produce new individuals to enhance or restore native populations.

The impact of COVID-19 on population oral health

Over the last year, coronavirus disease 2019 (COVID-19) has accumulated over 37 million cases and over one million deaths worldwide (WHO, 2020). With no population immunity or vaccine at hand, all but fifteen countries issued 'stay at home' orders in a bid to contain the spread of the virus and limit the healthcare burden. 'Lockdown' included closure of dental practices. Both the virus itself and the various Government responses have had a profound impact on the work, home and social lives of the entire population and are likely to impact the oral health of many people. These oral health effects can be attributed to those caused directly by the virus and those caused indirectly through the subsequent societal response. Direct effects of COVID-19 on oral health include ageusia (an official symptom of COVID-19) and case reports of vesiculobullous lesions and necrotising periodontal disease (Patel and Woolley 2020). The ageusia associated with COVID-19 is transient and reports of other oral manifestations are based on low-grade and disputed evidence. The direct effects of COVID-19 are likely to be of modest consequence for population oral health.

Cryopreservation and Laser Nanowarming of Zebrafish Embryos Followed by Hatching and Spawning

This study shows for the first time the ability to rewarm cryopreserved zebrafish embryos that grow into adult fish capable of breeding normally. The protocol employs a single injection of cryoprotective agents (CPAs) and gold nanorods (GNRs) into the yolk and immersion in a precooling bath to dehydrate the perivitelline space. Then embryos are encapsulated within CPA and GNR droplets, plunged into liquid nitrogen, cryogenically stabilized, and rewarmed by a laser pulse. Postlaser nanowarming, embryos (n = 282) exhibit intact structure by 1 h (40%), continued development after 3 h (22%), movement after 24 h (11%), hatching after 48 h (9%), and swimming after Day 5 (3%). Finally, from fish that survives till Day 5, two larvae are grown to adulthood and spawned, yielding survival comparable to an unfrozen control. Future efforts will focus on improving the survival to adulthood and developing methods to cryopreserve large numbers of embryos for research, aquaculture, and biodiversity preservation.

First instance of settlement by cryopreserved coral larvae in symbiotic association with dinoflagellates

Coral reefs are suffering on a global scale due to human impacts, thereby necessitating cryopreservation efforts. The objective of this study was to develop a suitable vitrification and laser warming protocol for larvae of the scleractinian coral Seriatopora caliendrum, which inherit their dinoflagellate algal symbionts vertically. Toxicity experiments were conducted with the cryoprotectants (CPAs) ethylene glycol (EG), propylene glycol (PG), dimethyl sulfoxide (DMSO), glycerol (GLY), and methanol (METH; listed in order from least to most toxic), and larvae were subjected to vitrification and laser warming using 2 M EG + 1 M PG and 2 M EG + 1 M DMSO. Vitrification and laser warming (300 V, 10 ms pulse width, 2 mm beam diameter) using a vitrification solution of 2 M EG + 1 M PG, 40% w/v Ficoll, and 10% v/v gold nanobars (GNB) at a final concentration of 1.2 × 1018 GNB/mL and a characteristic wavelength of 535 nm resulted in larvae with vitality and settlement percentages of 55 and 9%, respectively. This represents the first successful instance of cryopreservation of coral larvae that proceeded to settle upon warming, and suggests that the vitrification and ultra-fast laser warming approach may be applicable to other threatened marine species.

Challenges Related to the Implementation of an EMS-Administered, Large Vessel Occlusion Stroke Score

Introduction

There is considerable interest in triaging victims of large vessel occlusion (LVO) strokes to comprehensive stroke centers. Timely access to interventional therapy has been linked to improved stroke outcomes. Accurate triage depends upon the use of a validated screening tool in addition to several emergency medical system (EMS)-specific factors. This study examines the integration of a modified Rapid Arterial oCcclusion Evaluation (mRACE) score into an existing stroke treatment protocol.

Methods

We performed a retrospective review of EMS and hospital charts of patients transported to a single comprehensive stroke center. Adult patients with an EMS provider impression of “stroke/TIA,” “CVA,” or “neurological problem” were included for analysis. EMS protocols mandated the use of the Cincinnati Prehospital Stroke Score (CPSS). The novel protocol authorized the use of the mRACE score to identify candidates for triage directly to the comprehensive stroke center. We calculated specificity and sensitivity for various stroke screens (CPSS and a mRACE exam) for the detection of LVO stroke. The score’s metrics were evaluated as a surrogate marker for a successful EMS triage protocol.

Results

We included 312 prehospital charts in the final analysis. The CPSS score exhibited reliable sensitivity at 85%. Specificity of CPSS for an LVO was calculated at 73%. For an mRACE score of five or greater, the sensitivity was 25%. Specificity for mRACE was calculated at 75%. The positive predictive value of the mRACE score for an LVO was estimated at 12.50%.

Conclusion

In this retrospective study of patients triaged to a single comprehensive stroke center, the addition of an LVO-specific screening tool failed to improve accuracy. Reliable triage of LVO strokes in the prehospital setting is a challenging task. In addition to statistical performance of a particular stroke score, a successful EMS protocol should consider system-based factors such as provider education and training. Study limitations can inform future iterations of LVO triage protocols.

Relationship between Hypotension and Cerebral Ischemia during Hemodialysis

The relationship between BP and downstream ischemia during hemodialysis has not been characterized. We studied the dynamic relationship between BP, real-time symptoms, and cerebral oxygenation during hemodialysis, using continuous BP and cerebral oxygenation measurements prospectively gathered from 635 real-world hemodialysis sessions in 58 prevalent patients. We examined the relationship between BP and cerebral ischemia (relative drop in cerebral saturation >15%) and explored the lower limit of cerebral autoregulation at patient and population levels. Furthermore, we estimated intradialytic exposure to cerebral ischemia and hypotension for each patient, and entered these values into multivariate models predicting change in cognitive function. In all, 23.5% of hemodialysis sessions featured cerebral ischemia; 31.9% of these events were symptomatic. Episodes of hypotension were common, with mean arterial pressure falling by a median of 22 mmHg (interquartile range, 14.3-31.9 mmHg) and dropping below 60 mmHg in 24% of sessions. Every 10 mmHg drop from baseline in mean arterial pressure associated with a 3% increase in ischemic events (P<0.001), and the incidence of ischemic events rose rapidly below an absolute mean arterial pressure of 60 mmHg. Overall, however, BP poorly predicted downstream ischemia. The lower limit of cerebral autoregulation varied substantially (mean 74.1 mmHg, SD 17.6 mmHg). Intradialytic cerebral ischemia, but not hypotension, correlated with decreased executive cognitive function at 12 months (P=0.03). This pilot study demonstrates that intradialytic cerebral ischemia occurs frequently, is not easily predicted from BP, and may be clinically significant.

A Procedure-Spanning Analysis of Plasma Membrane Integrity for Assessment of Cell Viability in Sperm Cryopreservation of Zebrafish Danio rerio

The goal of this study was to evaluate plasma membrane integrity and motility for zebrafish sperm quality assessment along the cryopreservation pathway-from sample collection through refrigerated storage, cryoprotectant equilibration, freezing, thawing, and fertilization. The objectives were to: (1) evaluate the effects of osmolality, extender, and refrigerated storage on sperm plasma membrane integrity and motility, and (2) compare cryopreservation of sperm from farm-raised and well-characterized research populations by evaluating motility and membrane integrity of fresh, post-equilibration (before freezing) and post-thaw sperm, and post-thaw fertility. Osmolality, extender, and storage time each influenced sperm motility and membrane integrity. Isotonic osmolality showed the best protection for motility and membrane integrity compared to hypotonic and hypertonic osmolalities. Of the four tested extenders, Hanks' balanced salt solution (HBSS) and Ca(2+)-free HBSS showed the best protection compared with NaCl and glucose, and sperm retained motility and membrane integrity for 24 h of refrigerated storage. Sperm cryopreservation of zebrafish from a farm population (n = 20) and an AB research line (n = 20) showed significant differences in post-thaw fertility (32% ± 18% vs. 73% ± 21%). No differences were found in post-thaw motility, although the farm-raised zebrafish possessed a larger body size, testis weight, and higher fresh motility. Correlation analysis of pooled data did not identify correlations among motility, flow cytometry analysis of membrane integrity and recognizable cells, and post-thaw sperm fertility (p ≥ 0.202). More research is needed to standardize the fertilization conditions especially sperm-to-egg ratio to avoid possible overabundance of sperm to obscure the differences.

Determination of sperm concentration using flow cytometry with simultaneous analysis of sperm plasma membrane integrity in zebrafish Danio rerio

Control of sperm concentration is required to ensure consistent and reproducible results for cryopreservation and in vitro fertilization protocols. Determination of sperm concentration is traditionally performed with a counting chamber (e.g., hemocytometer), or more recently with a spectrophotometer. For small-sized biomedical model fishes, the availability of sperm sample is limited to microliters, so it is desirable to develop fast and accurate approaches for concentration determination that also minimize sample use. In this study, a new approach was developed for sperm concentration determination using a flow cytometer (Accuri C6, BD Biosciences, San Jose, CA) with simultaneous measurement of sperm membrane integrity after fluorescent staining with SYBR(®) -14 and propidium iodide (PI) in sperm from Zebrafish Danio rerio. The goal was to develop a protocol for simultaneous determination of sperm quality and quantity by flow cytometry. The objectives were to (1) determine the effects of sample volume (250 and 500 µl) and analysis volume (10 and 50 µl) on the accuracy of particle counting using standard volumetric validation beads; (2) identify the effective range of sperm concentrations that flow cytometry can measure; (3) test the precision and reproducibility of the sperm concentration measurements; and (4) verify the flow cytometry approach by comparison with measurement with a hemocytometer and a microspectrophotometer. Sample volumes of 250 and 500 µl and analysis volumes of 10 and 50 µl did not affect bead count with the factory-set flow rates of "medium" or "fast," and the precision and accuracy was retained across a concentration range of 1 × 10(3) -1 × 10(7) cells/ml. The approach developed in this study was comparable to traditional methodologies such as hemocytometer or microspectrophotometer. This study provides an efficient, accurate, and rapid method for determination of sperm concentration using flow cytometry while providing simultaneous assessment of sperm membrane integrity. Such approaches can reduce the time needed for quantity assessment and maximize the use of valuable sperm samples. © 2015 International Society for Advancement of Cytometry.

Non-contact measurement of oxygen saturation with an RGB camera

A novel method (Sophia) is presented to track oxygen saturation changes in a controlled environment using an RGB camera placed approximately 1.5 m away from the subject. The method is evaluated on five healthy volunteers (Fitzpatrick skin phenotypes II, III, and IV) whose oxygen saturations were varied between 80% and 100% in a purpose-built chamber over 40 minutes each. The method carefully selects regions of interest (ROI) in the camera image by calculating signal-to-noise ratios for each ROI. This allows it to track changes in oxygen saturation accurately with respect to a conventional pulse oximeter (median coefficient of determination, 0.85).

Vitrification of Sperm from Marine Fishes: Effect on Motility and Membrane Integrity

Our goal was to develop a standardized approach for sperm vitrification of marine fishes that can be applied generally in aquatic species. The objectives were to: 1) estimate acute toxicity of cryoprotectants over a range of concentrations; 2) evaluate the properties of vitrification solutions (VS); 3) evaluate different thawing solutions, and 4) evaluate sperm quality after thawing by examination of motility and membrane integrity. Sperm were collected from red snapper (Lutjanus campechanus), spotted seatrout (Cynoscion nebulosus), and red drum (Sciaenops ocellatus). A total of 29 combinations of cryoprotectants were evaluated for toxicity and glass formation. Samples were loaded onto 10-µL polystyrene loops and plunged into liquid nitrogen. There was a significant difference (P < 0.05) in post-thaw motility among VS and among species when using the same VS. The sperm in VS of 15% DMSO + 15% ethylene glycol + 10% glycerol + 1% X-1000™ + 1% Z-1000™ had an average post-thaw motility of 58% and membrane integrity of 19% for spotted seatrout, 38% and 9% for red snapper, and 30% and 19% for red drum. Adaptations by marine fish to high osmotic pressures could explain the survival in the high cryoprotectant concentrations. Vitrification offers an alternative to conventional cryopreservation.

How well does physician selection of microbiologic tests identify Clostridium difficile and other pathogens in paediatric diarrhoea? Insights using multiplex PCR-based detection

The objective of this study was to compare the aetiologic yield of standard-of-care microbiologic testing ordered by physicians with that of a multiplex PCR platform. Stool specimens obtained from children and young adults with gastrointestinal illness were evaluated by standard laboratory methods and a developmental version of the FilmArray Gastrointestinal (GI) Diagnostic System (FilmArray GI Panel), a rapid multiplex PCR platform that detects 23 bacterial, viral and protozoal agents. Results were classified according to the microbiologic tests requested by the treating physician. A median of three (range 1-10) microbiologic tests were performed by the clinical laboratory during 378 unique diarrhoeal episodes. A potential aetiologic agent was identified in 46% of stool specimens by standard laboratory methods and in 65% of specimens tested using the FilmArray GI Panel (p < 0.001). For those patients who only had Clostridium difficile testing requested, an alternative pathogen was identified in 29% of cases with the FilmArray GI Panel. Notably, 11 (12%) cases of norovirus were identified among children who only had testing for Clostridium difficile ordered. Among those who had C. difficile testing ordered in combination with other tests, an additional pathogen was identified in 57% of stool specimens with the FilmArray GI Panel. For patients who had no C. difficile testing performed, the FilmArray GI Panel identified a pathogen in 63% of cases, including C. difficile in 8%. Physician-specified laboratory testing may miss important diarrhoeal pathogens. Additionally, standard laboratory testing is likely to underestimate co-infections with multiple infectious diarrhoeagenic agents.

Sources of variation in flow cytometric analysis of aquatic species sperm: The effect of cryoprotectants on flow cytometry scatter plots and subsequent population gating

The use of fluorescent staining and flow cytometry to assess sperm quality in aquatic species has increased over the past decade, but comparisons among studies are difficult or impossible due to variation in application, analysis, and reporting of protocols and data.The goal of the present study was to determine the effect of exposure to two cryoprotectants commonly used for cryopreservation of sperm from aquatic species on the accuracy of flow cytometric assessment of sperm quality.Membrane integrity of zebrafish (Danio rerio) sperm exposed to 10% and 20%methanol and dimethyl sulfoxide (DMSO)in 300 mOsm kg(-1) Hanks' balanced salt solution (HBSS) or calcium-free HBSSwas determined using SYBR 14/propidium iodide staining. Both cryoprotectants significantly affected forward-scatter and side-scatter characteristics of sperm samples, resulting in significant changes in the number of total and gated events, and in the number and percentage of intact cells. These results indicate that it cannot be assumed that the approach to flow cytometric analysis of fresh sperm will be applicable to cryoprotectant-treated or cryopreserved sperm. In total, we document examples of five potentially interacting factors that produce errors of 5 to 50% each, resulting in underestimates and overestimates of total and intact sperm (actual numbers and percentages) in the presence of the two most commonly used cryoprotectants at the concentrations used most often for cryopreservation of sperm from aquatic species. This study provides methods to reduce or eliminate these errors and recommendations necessary for standardization and reporting.

Consensus statement by hospital based dentists providing dental treatment for patients with inherited bleeding disorders

Avoidance of dental care and neglect of oral health may occur in patients with inherited bleeding disorders because of concerns about perioperative and postoperative bleeding, but this is likely to result in the need for crisis care, and more complex and high-risk procedures. Most routine dental care in this special needs group can be safely managed in the general dental setting following consultation with the patient's haematologist and adherence to simple protocols. Many of the current protocols for dental treatment of patients with inherited bleeding disorders were devised many years ago and now need revision. There is increasing evidence that the amount of factor cover previously recommended for dental procedures can now be safely reduced or may no longer be required in many cases. There is still a need for close cooperation and discussion between the patient's haematologist and dental surgeon before any invasive treatment is performed. A group of hospital based dentists from centres where patients with inherited bleeding disorders are treated met and, after discussions, a management protocol for dental treatment was formulated.

Production of F₁ offspring with vitrified sperm from a live-bearing fish, the green swordtail Xiphophorus hellerii

This study reports the first production of offspring with vitrified sperm from a live-bearing fish Xiphophorus hellerii. The overall goal of this study was to develop streamlined protocols for integration into a standardized approach for vitrification of aquatic species germplasm. The objectives were to (1) estimate acute toxicity of cryoprotectants, (2) evaluate vitrification solutions, (3) compare different thawing methods, (4) evaluate membrane integrity of post-thaw sperm vitrified in different cryoprotectants, and (5) evaluate the fertility of vitrified sperm. Nine cryoprotectants and two commercial vitrification additives were tested for acute toxicity and glass forming ability, alone and in combination. Two vitrification solutions, 40% glycerol (Gly) and 20% Gly+20% ethylene glycol (EG) in 500 mOsmol/kg Hanks' balanced salt solution (HBSS), were selected for vitrification of 10 μL sperm samples using inoculating loops plunged into liquid nitrogen. Samples were thawed at 24°C (one loop in 5 μL of HBSS or three loops in 500 μL of HBSS). Samples thawed in 500 μL were concentrated by centrifugation (1000 g for 5 min at 4°C) into 5 μL for artificial insemination. Offspring were produced from virgin females inseminated with sperm vitrified with 20% Gly+20% EG and concentrated by centrifugation.

Control of equine influenza: scenario testing using a realistic metapopulation model of spread

We present a metapopulation model of the spread of equine influenza among thoroughbred horses parametrized with data from a 2003 outbreak in Newmarket, UK. The number of horses initially susceptible is derived from a threshold theorem and a published statistical model. Two simulated likelihood-based methods are used to find the within- and between-yard transmissions using both exponential and empirical latent and infectious periods. We demonstrate that the 2003 outbreak was largely locally driven and use the parametrized model to address important questions of control. The chance of a large epidemic is shown to be largely dependent on the size of the index yard. The impact of poor responders to vaccination is estimated under different scenarios. A small proportion of poor responders strongly influences the efficiency of vaccine policies, which increases risk further when the vaccine and infecting strains differ following antigenic drift. Finally, the use of vaccinating in the face of an outbreak is evaluated at a global and individual management group level. The benefits for an individual horse trainer are found to be substantial, although this is influenced by the behaviour of other trainers.

Outcomes of antifungal prophylaxis in high-risk liver transplant recipients

Antifungal prophylaxis for liver transplant recipients (LTRs) is common among patients considered at high risk of infection, but optimal prophylaxis duration and drug has not been defined. This study aimed to assess the effects of 14 days of antifungal therapy prophylaxis in reducing proven invasive fungal infections (IFI) in high-risk subjects. Eligible subjects who met 2 or more risk criteria were randomized 1:1 to the treatment arms (liposomal amphotericin B or fluconazole) and were followed for 100 days post transplantation for evidence of IFI. The study was designed to enroll 300 subjects, but was closed early for insufficient enrollment. A total of 71 subjects were enrolled and randomized. Two-thirds of subjects completed 14 days of study therapy. Ten subjects developed proven or probable IFI with Candida species (9 subjects) and Cryptococcus neoformans (1 subject); rates were similar in the 2 treatment arms. Eleven subjects died, but no death was attributed to study drug or IFI. In summary, high-risk LTRs tolerated antifungal prophylaxis well, and rates of IFI were lower than previously reported in untreated high-risk LTRs.

Clinical leadership in contemporary clinical practice: implications for nursing in Australia

BACKGROUND

Leadership in the clinical practice environment is important to ensure both optimal patient outcomes and successive generations of motivated and enthusiastic clinicians.

AIM

The present paper seeks to define and describe clinical leadership and identify the facilitators and barriers to clinical leadership. We also describe strategies to develop clinical leaders in Australia. Key drivers to the development of nursing leaders are strategies that recognize and value clinical expertise. These include models of care that highlight the importance of the nursing role; evidence-based practice and measurement of clinical outcomes; strategies to empower clinicians and mechanisms to ensure participation in clinical decision-making.

KEY ISSUES

Significant barriers to clinical leadership are organizational structures that preclude nurses from clinical decision making; the national shortage of nurses; fiscal constraints; absence of well evaluated models of care and trends towards less skilled clinicians.

CONCLUSIONS

Systematic, strategic initiatives are required to nurture and develop clinical leaders. These strategies need to be collegial collaborations between the academic and health care sectors in order to provide a united voice for advancing the nursing profession.