A pheromone antagonist liberates female sea lamprey from a sensory trap to enable reliable communication.

The evolution of male signals and female preferences remains a central question in the study of animal communication. The sensory trap model suggests males evolve signals that mimic cues used in nonsexual contexts and thus manipulate female behavior to generate mating opportunities. Much evidence supports the sensory trap model, but how females glean reliable information from both mimetic signals and their model cues remains unknown. We discovered a mechanism whereby a manipulative male signal guides reliable communication in sea lamprey (Petromyzon marinus). Migratory sea lamprey follow a larval cue into spawning streams; once sexually mature, males release a pheromone that mimics the larval cue and attracts females. Females conceivably benefit from the mimetic pheromone during mate search but must discriminate against the model cue to avoid orienting toward larvae in nearby nursery habitats. We tested the hypothesis that spawning females respond to petromyzonol sulfate (PZS) as a behavioral antagonist to avoid attraction to the larval cue while tracking the male pheromone despite each containing attractive 3-keto petromyzonol sulfate (3kPZS). We found 1) PZS inhibited electrophysiological responses to 3kPZS and abated preferences for 3kPZS when mixed at the same or greater concentrations, 2) larvae released more PZS than 3kPZS whereas males released more 3kPZS than PZS, and 3) mixtures of 3kPZS and PZS applied at ratios measured in larval and male odorants resulted in the discrimination observed between the natural odors. Our study elucidates how communication systems that arise via deception can facilitate reliable communication.

Convergent olfactory trace amine-associated receptors detect biogenic polyamines with distinct motifs via a conserved binding site.

Biogenic amines activate G-protein-coupled receptors (GPCRs) in the central nervous system in vertebrate animals. Several biogenic amines, when excreted, stimulate trace amine-associated receptors (TAARs), a group of GPCRs in the main olfactory epithelium, and elicit innate behaviors. How TAARs recognize amines with varying numbers of amino groups is largely unknown. We reasoned that a comparison between lamprey and mammalian olfactory TAARs, which are thought to have evolved independently but show convergent responses to polyamines, may reveal structural determinants of amine recognition. Here, we demonstrate that sea lamprey TAAR365 (sTAAR365) responds strongly to biogenic polyamines cadaverine, putrescine, and spermine, and shares a similar response profile as a mammalian TAAR (mTAAR9). Docking and site-directed mutagenesis analyses show that both sTAAR365 and mTAAR9 recognize the two amino groups of cadaverine with the conserved Asp3.32 and Tyr6.51 residues. sTAAR365, which has remarkable sensitivity for cadaverine (EC50 = 4 nM), uses an extra residue, Thr7.42, to stabilize ligand binding. These cadaverine recognition sites also interact with amines with four and three amino groups (spermine and spermidine, respectively). Glu7.36 of sTAAR365 cooperates with Asp3.32 and Thr7.42 to recognize spermine, whereas mTAAR9 recognizes spermidine through an additional aromatic residue, Tyr7.43. These results suggest a conserved mechanism whereby independently evolved TAAR receptors recognize amines with two, three, or four amino groups using the same recognition sites, at which sTAAR365 and mTAAR9 evolved distinct motifs. These motifs interact directly with the amino groups of the polyamines, a class of potent and ecologically important odorants, mediating olfactory signaling.

Spermine in semen of male sea lamprey acts as a sex pheromone.

Semen is fundamental for sexual reproduction. The non-sperm part of ejaculated semen, or seminal plasma, facilitates the delivery of sperm to the eggs. The seminal plasma of some species with internal fertilization contains anti-aphrodisiac molecules that deter promiscuity in post-copulatory females, conferring fitness benefits to the ejaculating male. By contrast, in some taxa with external fertilization such as fish, exposure to semen promotes spawning behaviors. However, no specific compounds in semen have been identified as aphrodisiac pheromones. We sought to identify a pheromone from the milt (fish semen) of sea lamprey (Petromyzon marinus), a jawless fish that spawns in lek-like aggregations in which each spermiating male defends a nest, and ovulatory females move from nest to nest to mate. We postulated that milt compounds signal to ovulatory females the presence of spawning spermiating males. We determined that spermine, an odorous polyamine initially identified from human semen, is indeed a milt pheromone. At concentrations as low as 10-14 molar, spermine stimulated the lamprey olfactory system and attracted ovulatory females but did not attract males or pre-ovulatory females. We found spermine activated a trace amine-associated receptor (TAAR)-like receptor in the lamprey olfactory epithelium. A novel antagonist to that receptor nullified the attraction of ovulatory females to spermine. Our results elucidate a mechanism whereby a seminal plasma pheromone attracts ready-to-mate females and implicates a possible conservation of the olfactory detection of semen from jawless vertebrates to humans. Milt pheromones may also have management implications for sea lamprey populations.

Bile acid production is life-stage and sex-dependent and affected by primer pheromones in the sea lamprey.

Pheromonal bile salts are important for sea lampreys (Petromyzon marinus Linnaeus) to complete their life cycle. The synthesis and release of a releaser/primer pheromone 3-keto petromyzonol sulfate (3kPZS) by spermiating males have been well characterized. 3kPZS evokes sexual behaviors in ovulatory females, induces immediate 3kPZS release in spermiating males, and elicits neuroendocrine responses in prespawning adults. Another primer pheromone released by spermiating males, 3-keto allocholic acid (3kACA), antagonizes the neuroendocrine effects of 3kPZS in prespermiating males. However, the effects of 3kACA and 3kPZS on pheromone production in prespawning adults is unclear. To understand the foundation of pheromone production, we examined sea lamprey bile salt levels at different life stages. To investigate the priming effects of 3kACA and 3kPZS, we exposed prespawning adults with vehicle or synthetic 3kACA or 3kPZS. We hypothesized that endogenous bile salt levels were life-stage and sex-dependent, and differentially affected by 3kACA and 3kPZS in prespawning adults. Using ultra-performance liquid chromatography tandem mass spectrometry, we found that sea lampreys contained distinct mixtures of bile salts in the liver and plasma at different life stages. Males usually contained higher amounts of bile salts than females. Petromyzonamine disulfate was the most abundant C27 bile salt and petromyzonol sulfate was the most abundant C24 bile salt. Waterborne 3kACA and 3kPZS exerted differential effects on bile salt production in the liver and gill, their circulation and clearance in the plasma, and their release into water. We conclude that bile salt levels are life-stage and sex-dependent and differentially affected by primer pheromones.

Fatty-acid derivative acts as a sea lamprey migratory pheromone.

Olfactory cues provide critical information for spatial orientation of fish, especially in the context of anadromous migrations. Born in freshwater, juveniles of anadromous fish descend to the ocean where they grow into adults before migrating back into freshwater to spawn. The reproductive migrants, therefore, are under selective pressures to locate streams optimal for offspring survival. Many anadromous fish use olfactory cues to orient toward suitable streams. However, no behaviorally active compounds have been identified as migratory cues. Extensive studies have shown that the migratory adult sea lampreys (Petromyzon marinus), a jawless fish, track a pheromone emitted by their stream-dwelling larvae, and, consequently, enter streams with abundant larvae. We fractionated extracts of larval sea lamprey washings with guidance from a bioassay that measures in-stream migratory behaviors of adults and identified four dihydroxylated tetrahydrofuran fatty acids, of which (+)-(2S,3S,5R)-tetrahydro-3-hydroxy-5-[(1R)-1-hydroxyhexyl]-2-furanoctanoic acid was shown as a migratory pheromone. The chemical structure was elucidated by spectroscopies and confirmed by chemical synthesis and X-ray crystallography. The four fatty acids were isomer-specific and enantiomer-specific in their olfactory and behavioral activities. A synthetic copy of the identified pheromone was a potent stimulant of the adult olfactory epithelium, and, at 5 × 10-13 M, replicated the extracts of larval washings in biasing adults into a tributary stream. Our results reveal a pheromone that bridges two distinct life stages and guides orientation over a large space that spans two different habitats. The identified molecule may be useful for control of the sea lamprey.

Estimating the economic cost of nurse sensitive adverse events amongst patients in medical and surgical settings.

AIMS: To identify the costs associated with nurse sensitive adverse events and the impact of these events on patients' length of stay. DESIGN: Retrospective cohort study using administrative hospital data. METHODS: Data were sourced from patient discharge information (N = 5544) from six acute wards within three hospitals (July 2016-October 2017). A retrospective patient record review was undertaken by extracting data from the hospitals' administrative systems on inpatient discharges, length of stay and diagnoses; eleven adverse events sensitive to nurse staffing were identified within the administrative system. A negative binomial regression is employed to assess the impact of nurse sensitive adverse events on length of stay. RESULTS: Sixteen per cent of the sample (n = 897) had at least one nurse sensitive adverse event during their episode of care. The model revealed when age, gender, admission type and complexity are controlled for, each additional nurse sensitive adverse event experienced by a patient was associated with an increase in the length of stay beyond the national average by 0.48 days (p = .001). Applying this to the daily average cost of inpatient stay per patient (€1456), we estimate the average cost associated with each nurse sensitive adverse event to be €694. Extrapolating this nationally, the economic cost of nurse sensitive adverse events to the health service in Ireland is estimated to be €91.3 million annually. CONCLUSION: These potentially avoidable events are associated with a significant economic burden to health systems. The estimates provided here can be used to inform and prepare the way for future economic evaluations of nurse staffing initiatives that aim to improve care and safety. IMPACT: As many of these nurse sensitive adverse events are avoidable, in addition to patient benefits, there is a potential substantial financial return on investment from strategies such as improved nurse staffing that can reduce their occurrence.

Safe and competent nursing care: An argument for a minimum standard?

There is no agreed minimum standard with regard to what is considered safe, competent nursing care. Limited resources and organizational constraints make it challenging to develop a minimum standard. As part of their everyday practice, nurses have to ration nursing care and prioritize what care to postpone, leave out, and/or omit. In developed countries where public healthcare is tax-funded, a minimum level of healthcare is a patient right; however, what this entails in a given patient's actual situation is unclear. Thus, both patients and nurses would benefit from the development of a minimum standard of nursing care. Clarity on this matter is also of ethical and legal concern. In this article, we explore the case for developing a minimum standard to ensure safe and competent nursing care services. Any such standard must encompass knowledge of basic principles of clinical nursing and preservation of moral values, as well as managerial issues, such as manpower planning, skill-mix, and time to care. In order for such standards to aid in providing safe and competent nursing care, they should be in compliance with accepted evidence-based nursing knowledge, based on patients' needs and legal rights to healthcare and on nurses' codes of ethics. That is, a minimum standard must uphold a satisfactory level of quality in terms of both professionalism and ethics. Rather than being fixed, the minimum standard should be adjusted according to patients' needs in different settings and may thus be different in different contexts and countries.

Socioeconomic disparities in access to intensive insulin regimens for adults with type 1 diabetes: a qualitative study of patient and healthcare professional perspectives.

BACKGROUND: Type 1 diabetes is a complex chronic condition which requires lifelong treatment with insulin. Health outcomes are dependent on ability to self-manage the condition. Socioeconomic inequalities have been demonstrated in access to treatment and health outcomes for adults with type 1 diabetes; however, there is a paucity of research exploring how these disparities occur. This study explores the influence of socioeconomic factors in gaining access to intensive insulin regimens for adults with type 1 diabetes. METHODS: We undertook a qualitative descriptive study informed by a phenomenological perspective. In-depth face-to-face interviews were conducted with 28 patients and 6 healthcare professionals involved in their care. The interviews were analysed using a thematic approach. The Candidacy theory for access to healthcare for vulnerable groups framed the analysis. RESULTS: Access to intensive insulin regimens was through hospital-based specialist services in this sample. Patients from lower socioeconomic groups had difficulty accessing hospital-based services if they were in low paid work and because they lacked the ability to navigate the healthcare system. Once these patients were in the specialist system, access to intensive insulin regimens was limited by non-alignment with healthcare professional goals, poor health literacy, psychosocial problems and poor quality communication. These factors could also affect access to structured diabetes education which itself improved access to intensive insulin regimens. Contact with diabetes specialist nurses and attendance at structured diabetes education courses could ameliorate these barriers. CONCLUSIONS: Access to intensive insulin regimens was hindered for people in lower socioeconomic groups by a complex mix of factors relating to the permeability of specialist services, ability to navigate the healthcare system and patient interactions with healthcare providers. Improving access to diabetes specialist nurses and structured diabetes education for vulnerable patients could lessen socioeconomic disparities in both access to services and health outcomes.

Enabling the hypothesis-driven prioritization of ligand candidates in big databases: Screenlamp and its application to GPCR inhibitor discovery for invasive species control.

While the advantage of screening vast databases of molecules to cover greater molecular diversity is often mentioned, in reality, only a few studies have been published demonstrating inhibitor discovery by screening more than a million compounds for features that mimic a known three-dimensional (3D) ligand. Two factors contribute: the general difficulty of discovering potent inhibitors, and the lack of free, user-friendly software to incorporate project-specific knowledge and user hypotheses into 3D ligand-based screening. The Screenlamp modular toolkit presented here was developed with these needs in mind. We show Screenlamp's ability to screen more than 12 million commercially available molecules and identify potent in vivo inhibitors of a G protein-coupled bile acid receptor within the first year of a discovery project. This pheromone receptor governs sea lamprey reproductive behavior, and to our knowledge, this project is the first to establish the efficacy of computational screening in discovering lead compounds for aquatic invasive species control. Significant enhancement in activity came from selecting compounds based on one of the hypotheses: that matching two distal oxygen groups in the 3D structure of the pheromone is crucial for activity. Six of the 15 most active compounds met these criteria. A second hypothesis-that presence of an alkyl sulfate side chain results in high activity-identified another 6 compounds in the top 10, demonstrating the significant benefits of hypothesis-driven screening.

Petromylidenes A⁻C: 2-Alkylidene Bile Salt Derivatives Isolated from Sea Lamprey (Petromyzon marinus).

Three novel bile acid derivatives, petromylidenes A⁻C (1⁻3), featuring uncommon alkylidene adductive scaffolds, were isolated from water conditioned with sexually mature male sea lampreys (Petromyzon marinus). Their structures were elucidated by mass spectrometry and NMR spectroscopy, and by comparison to spectral data of related structures. The identification of compounds 1⁻3, further illustrates the structural diversity of the 5α bile salt family. Compounds 1⁻3 exhibited notable biological properties as well, including high olfactory potencies in adult sea lampreys and strong behavioral attraction of ovulated female sea lampreys. Electro-olfactogram recordings indicated that the limit of detection for 1 was 10-9 M, 2 was 10-11 M, and 3 was less than 10-13 M. These results suggested 1⁻3 were likely male pheromones, which guide reproductive behaviors in the sea lamprey.

Patient perspectives on barriers and enablers to the use and effectiveness of de-escalation techniques for the management of violence and aggression in mental health settings.

AIM: Investigate patient perspectives on barriers and enablers to the use and effectiveness of de-escalation techniques for aggression in mental health settings. BACKGROUND: De-escalation techniques are the recommended first-line intervention for the management of aggression in mental health settings internationally, yet use of higher risk restrictive practices persists. This indicates de-escalation techniques are not used at optimum frequency and/or there are important factors limiting their use and effect. DESIGN: Descriptive qualitative research using semi-structured interviews and Framework Analysis. METHODS: Inpatient interviews (N = 26) exploring staff, patient and environmental factors influencing the use and effectiveness of staff de-escalation were conducted mid-2014. Three service user researchers led analysis. RESULTS: Data were synthesized in three deductive themes relating to staff, patient and environmental influences on the use and effectiveness of de-escalation techniques. The dominant view was that restrictive practices, rather than de-escalation techniques, are used in response to escalating patient behaviour. Under-use of de-escalation techniques was attributed to: lack of staff reflection on culture and practice and a need to retain control/dominance over patients. Ward rules, patient factors and a lack of staff respect for patients diluted their effectiveness. Participants identified a systematic process of de-escalation, rule subversion, reduced social distance and staff authenticity as enablers of effective de-escalation. CONCLUSION: This study investigated patient perspectives on staff, patient and environmental influences on the use and effectiveness of de-escalation techniques. Our framework of barriers and enablers provides indicators of organizational/behaviour change targets for interventions seeking to reduce violence and restrictive practices through enhanced de-escalation techniques.

A protocol to measure the impact of intentional changes to nurse staffing and skill-mix in medical and surgical wards.

AIM: The aim of this research is to measure the impact that planned changes to nurse staffing and skill-mix have on patient, nurse, and organizational outcomes. BACKGROUND: It has been highlighted that there are several design limitations in studies that explore the relationship between nurse staffing and patient, nurse and organizational outcomes; not least that the vast majority of research in this area emanates from studies that are predominantly observational in design. There are limited studies that measure nurse, patient, organizational, and economic outcomes using a longitudinal design following a planned change in nurse staffing. DESIGN: The research will employ a longitudinal, multimethod approach to evaluate the impact that planned changes in nurse staffing and skill-mix have on wards in three pilot hospitals. METHODS: Administrative data collection will take place on a shift-by-shift basis prospectively over a three-year period including the measurement of nursing sensitive outcomes: cross-sectional patient experience data and nurse outcomes (nursing work, job satisfaction, burnout, missed care) will be collected at intervals prior to, during and after the implementation of planned changes in nurse staffing and skill-mix. Data will be analysed using interrupted time-series models, adjusted for key hospital, ward and patient-level factors. An economic costing of the changes will further investigate the resources required for the intervention that can then be aggregated to a national level for future roll-out plans. DISCUSSION: The study aims to provide evidence on the impact of planned changes to nurse staffing and skill-mix based on a systematic approach using a longitudinal design and to determine the extent to which the approach can be implemented at a national level.

Self-management for bipolar disorder and the construction of the ethical self.

The promotion of the self-managing capacities of people has become a marker of contemporary mental health practice, yet self-management remains a largely uncontested construct in mental health settings. This discourse analysis based upon the work of Foucault investigates self-management practices for bipolar disorder and their action upon how a person with bipolar disorder comes to think of who they are and how they should live. Using Foucault's framework for exploring the ethical self and transcripts of interviews with people living with bipolar disorder, this discourse analysis finds that the discursive practices of self-management for bipolar disorder are prescribing a restricted regime for living based upon the quintessential neo-liberal subject using practices that are focused upon managing an unreliable and problematic self. The article concludes with the proposition that the problem of bipolar disorder (for which self-management is an answer) is less about the object itself and more about how we construct the nature of the self. A Maori indigenous ontology is used here as an example of an alternative discursive resource through which people make sense of the self and which allows ways of thinking about self-management that engage with ambivalence and ambiguity rather than restriction and regulation.

Characterization of enamel caries lesions in rat molars using synchrotron X-ray microtomography.

Dental caries is a ubiquitous infectious disease with a nearly 100% lifetime prevalence. Rodent caries models are widely used to investigate the etiology, progression and potential prevention or treatment of the disease. To explore the suitability of these models for deeper investigations of intact surface zones during enamel caries, the structures of early-stage carious lesions in rats were characterized and compared with previous reports on white spot enamel lesions in humans. Synchrotron X-ray microcomputed tomography non-destructively mapped demineralization in carious rat molar specimens across a range of caries severity, identifying 52 lesions across the 30 teeth imaged. Of these lesions, 13 were shown to have intact surface zones. Depth profiles of fractional mineral density were qualitatively similar to lesions in human teeth. However, the thickness of the surface zone in the rat model ranges from 10 to 58 µm, and is therefore significantly thinner than in human enamel. These results indicate that a fraction of lesions in rat caries possess an intact surface zone and are qualitatively similar to human lesions at the micrometer scale. This suggests that rat caries models may be a suitable analog through which to investigate the structure of surface zone enamel and its role during dental caries.

Three Novel Bile Alcohols of Mature Male Sea Lamprey (Petromyzon marinus) Act as Chemical Cues for Conspecifics.

Sea lamprey, Petromyzon marinus, rely heavily on chemical cues that mediate their life history events, such as migration and reproduction. Here, we describe petromyzone A-C (1-3), three novel bile alcohols that are highly oxidized and sulfated, isolated from water conditioned with spermiated male sea lamprey. Structures of these compounds were unequivocally established by spectroscopic analyses and by comparison with spectra of known compounds. Electro-olfactogram recordings showed that 1 at 10-11 M was stimulatory to the adult sea lamprey olfactory epithelium, while 2 and 3 were stimulatory at 10-13 M. Behavioral assays indicated that 1 is attractive, 2 is not attractive or repulsive, and 3 is repulsive to ovulated female sea lamprey. The results suggest that 1 and 2 may be putative pheromones that mediate chemical communication in sea lamprey. The identification of these three components enhances our understanding of the structures and functions of sex pheromone components in this species and may provide useful behavioral manipulation tools for the integrated management of sea lamprey, a destructive invader in the Laurentian Great Lakes.

Tensions within management roles in healthcare organisations.

Aim This article reports the results of a study that gives an insight into ward leaders' perspectives of their leadership role and explores how they deliver leadership at ward level within organisational constraints and processes. Previous studies have been evaluations of clinical leadership in general, or literature reviews of the ward leader role. The aim of this study was to examine the leadership role of ward sisters and to understand how they lead improvements in quality of care on their wards. Methods A qualitative methodology was used, incorporating 19 in-depth interviews with ward leaders and modern matrons. Results Three main themes were identified: empty conformity, authority and autonomy, and visibility and leading by example. Participants aimed to be role models in leading and maintaining standards of care for patients, but this was sometimes constrained by organisational processes, lack of authority and autonomy, and lack of support and preparation. Conclusion Perceived differences between nursing and health service management mean that ward leaders' efforts to lead improvements in quality care are often undermined. Ward leaders must strike a balance between leading high-quality nursing care, in the context of organisational and political performance requirements, and the demands of administrative work, while often lacking autonomy and authority.

Quantification of Oxidized and Unsaturated Bile Alcohols in Sea Lamprey Tissues by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry.

A sensitive and reliable method was developed and validated for the determination of unsaturated bile alcohols in sea lamprey tissues using liquid-liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The liver, kidney, and intestine samples were extracted with acetonitrile and defatted by n-hexane. Gradient UHPLC separation was performed using an Acquity BEH C18 column with a mobile phase of water and methanol containing 20 mM triethylamine. Multiple reaction monitoring modes of precursor-product ion transitions for each analyte was used. This method displayed good linearity, with correlation coefficients greater than 0.99, and was validated. Precision and accuracy (RSD %) were in the range of 0.31%-5.28%, while mean recoveries were between 84.3%-96.3%. With this technique, sea lamprey tissue samples were analyzed for unsaturated bile alcohol analytes. This method is practical and particularly suitable for widespread putative pheromone residue analysis.

Transcription of Oxidative Stress Genes Is Directly Activated by SpxA1 and, to a Lesser Extent, by SpxA2 in Streptococcus mutans.

UNLABELLED: The SpxA1 and SpxA2 (formerly SpxA and SpxB) transcriptional regulators of Streptococcus mutans are members of a highly conserved family of proteins found in Firmicutes, and they were previously shown to activate oxidative stress responses. In this study, we showed that SpxA1 exerts substantial positive regulatory influence over oxidative stress genes following exposure to H2O2, while SpxA2 appears to have a secondary regulatory role. In vitro transcription (IVT) assays using purified SpxA1 and/or SpxA2 showed that SpxA1 and, less often, SpxA2 directly activate transcription of some of the major oxidative stress genes. Addition of equimolar concentrations of SpxA1 and SpxA2 to the IVT reactions neither enhanced transcription of the tested genes nor disrupted the dominant role of SpxA1. Substitution of a conserved glycine residue (G52) present in both Spx proteins by arginine (SpxG52R) resulted in strains that phenocopied the Δspx strains. Moreover, addition of purified SpxA1G52R completely failed to activate transcription of ahpC, sodA, and tpx, further confirming that the G52 residue is critical for Spx functionality. IMPORTANCE: Streptococcus mutans is a pathogen associated with the formation of dental caries in humans. Within the oral cavity, S. mutans routinely encounters oxidative stress. Our previous data revealed that two regulatory proteins, SpxA1 and SpxA2 (formerly SpxA and SpxB), bear high homology to the Spx regulator that has been characterized as a critical activator of oxidative stress genes in Bacillus subtilis. In this report, we prove that Spx proteins of S. mutans directly activate transcription of genes involved in the oxidative stress response, though SpxA1 appears to have a more dominant role than SpxA2. Therefore, the Spx regulators play a critical role in the ability of S. mutans to thrive within the oral cavity.

The collagen binding protein Cnm contributes to oral colonization and cariogenicity of Streptococcus mutans OMZ175.

Streptococcus mutans is the etiological agent of dental caries and one of the many bacterial species implicated in infective endocarditis. The expression of the collagen-binding protein Cnm by S. mutans has been associated with extraoral infections, but its relevance for dental caries has only been theorized to date. Due to the collagenous composition of dentinal and root tissues, we hypothesized that Cnm may facilitate the colonization of these surfaces, thereby enhancing the pathogenic potential of S. mutans in advancing carious lesions. As shown for extraoral endothelial cell lines, Cnm mediates the invasion of oral keratinocytes and fibroblasts by S. mutans. In this study, we show that in the Cnm(+) native strain, OMZ175, Cnm mediates stringent adhesion to dentinal and root tissues as well as collagen-coated surfaces and promotes both cariogenicity and carriage in vivo. In vitro, ex vivo, and in vivo experiments revealed that while Cnm is not universally required for S. mutans cariogenicity, it contributes to (i) the invasion of the oral epithelium, (ii) enhanced binding on collagenous surfaces, (iii) implantation of oral biofilms, and (IV) the severity of caries due to a native Cnm(+) isolate. Taken together, our findings reveal that Cnm is a colonization factor that contributes to the pathogenicity of certain S. mutans strains in their native habitat, the oral cavity.

The direct cost of intravenous insulin infusions to the NHS in England and Wales.

The cost of intravenous insulin infusion to the NHS is unknown. The aim of this study was to estimate the direct cost of insulin infusions to the NHS in England and Wales in the first 24-hour period of infusion. Data from the National Inpatient Diabetes Audit 2013 in the UK were used to estimate the number of insulin infusions in use across England and Wales. Costs were calculated for six models for setting up and maintenance of insulin infusions, depending on the extent of involvement of different healthcare professionals in the UK. In this study, the direct costs of intravenous insulin infusions to the NHS in England and Wales have been estimated to vary from £6.4-8.5 million in the first 24-hour period on infusion. More appropriate use of these infusions could result in substantial cost savings.