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BACKGROUND: Regional anaesthesia techniques, including the erector spinae fascial plane (ESP) block, reduce postoperative pain after video-assisted thoracoscopic surgery (VATS). Fascial plane blocks rely on spread of local anaesthetic between muscle layers, and thus, intermittent boluses might increase their clinical effectiveness. We tested the hypothesis that postoperative ESP analgesia with a programmed intermittent bolus (PIB) regimen is better than a continuous infusion (CI) regimen in terms of quality of recovery after VATS. METHODS: We undertook a prospective, double-blinded, randomised, controlled trial involving 60 patients undergoing VATS. All participants received ESP block catheters and were randomly assigned to CI or PIB of local anaesthetic regimen for postoperative analgesia. The primary outcome was Quality of Recovery-15 (QoR-15) score 24 h after surgery. Secondary outcomes included postoperative respiratory function, opioid consumption, verbal rating pain score, time to first mobilisation, nausea, vomiting, and length of hospital stay. RESULTS: Overall QoR-15 scores at 24 h after VATS were similar (PIB 115.5 [interquartile range 107-125] vs CI 110 [93-128]; Δ<6, P=0.29). The only quality of recovery descriptor showing a significant difference was nausea and vomiting, which was favourable in the PIB group (10 [10-10] vs 10 [7-10]; P=0.03). Requirement for rescue antiemetics up to 24 h after surgery was lower in the PIB group (4 [14%] vs 11 [41%]; P=0.04). There were no differences in other secondary outcomes between groups. CONCLUSIONS: Delivering ESP block analgesia after VATS via a PIB regimen resulted in similar QoR-15 at 24 h compared with a CI regimen.
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BACKGROUND: Prolonged media exposure after collective crises is widely shown to have adverse effects on people's mental health. Do these effects show variation across different countries? In the present study, we compared the link between media exposure related to COVID-19 and mental health-related outcomes in the United States and Italy, two countries with high levels of early COVID-19 prevalence. METHOD: Participants matched on age and gender in the United States (n = 415) and Italy (n = 442) completed assessments of media exposure, stress, anxiety, COVID-19 worry, and other variables shortly after the first wave of infections in 2020. RESULTS: COVID-19 related media exposure predicted higher levels of stress, anxiety, and COVID-19 worry, net of the effects of neuroticism, political identification, and demographics. Moreover, COVID-19 related media exposure interacted with country to predict more stress and COVID-19 worry in the United States than in Italy. CONCLUSIONS: Findings are among the first to document cross-national differences in the association of media exposure with mental health outcomes.
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COVID-19 , Humanos , Estados Unidos/epidemiología , COVID-19/epidemiología , Salud Mental , SARS-CoV-2 , Exposición a los Medios , Ansiedad/epidemiología , Ansiedad/psicologíaRESUMEN
Antibiotic use is an important component in dairy herd management both to treat bacterial diseases and to maximize animal welfare. However, there is concern among scientists that antibiotic misuse and/or overuse by farmers might promote the emergence of resistant pathogens. We conducted a cross-sectional web-based questionnaire study with dairy farmers/managers in New York, USA to evaluate their (i) level of concern about antibiotic resistance and (ii) interest in adopting new judicious antibiotic use practices regarding mastitis treatment. A total of 118 responses were subjected to statistical analysis. The findings revealed that nearly half (45%) of study participants were undecided or disagreed that antibiotic resistance due to antibiotic use in dairy farming may negatively impact the health of dairy cattle. In contrast, the majority (78%) of participants self-reported that they do not treat with antibiotics at the first sign of mastitis, and the majority (66%) have either fully or partially implemented culture-based mastitis treatment on their farm. The self-reported adoption of culture-based mastitis treatment practices was statistically significantly associated with higher numbers of injectable and intramammary doses of antibiotics used on the participants' farms. These findings will aid future research investigations on how to promote sustainable antibiotic use practices in dairy cattle.
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[This corrects the article DOI: 10.1093/beheco/arab007.].
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BACKGROUND: Current clinical tests do not provide a method to reliably measure closed chain hip extension. We developed the Posterior Standing Overhead Arm Reach (SOAR) test for this purpose. OBJECTIVES: This was a preliminary intrarater and interrater reliability and validity study of the Posterior SOAR test as a measure of functional hip extension. DESIGN: Cross-sectional. METHOD: Hip extension on the Posterior SOAR test was measured with a standard goniometer independently by two examiners. The test was then repeated using three-dimensional (3D) motion capture. Intraclass correlation coefficients (ICC) were used to determine the intrarater and interrater reliability of the goniometric measure and Pearson correlations were used to assess the relationship between measures obtained via goniometry and 3D motion capture. RESULTS: Fifty hips were assessed in 25 (14 female, 11 male) asymptomatic participants (mean age = 24.0 years, SD = 1.1). Intrarater reliability (ICC2,3) was 0.80 (95% CI = 0.68-0.88) for Examiner 1 and 0.77 (95% CI = 0.64-0.86) for Examiner 2, indicating excellent reliability. The standard error of the measure (SEM90) ranged from 2.5° to 3.0° with a minimal detectable change (MDC90) of 3.5° to 4.2°. Interrater reliability was good with ICC = 0.65 (95% CI = 0.36-0.80). Pearson correlations were significant with low to moderate associations (r = 0.36, P = 0.009; r = 0.51, P < 0.001). CONCLUSIONS: The Posterior SOAR test demonstrated excellent intrarater reliability, good interrater reliability, and low to moderate associations with 3D motion capture. The Posterior SOAR test has the potential to provide a reliable and accurate assessment of closed chain hip extension.
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Brazo , Posición de Pie , Adulto , Estudios Transversales , Femenino , Humanos , Masculino , Rango del Movimiento Articular , Reproducibilidad de los Resultados , Adulto JovenRESUMEN
Because sex ratios are a key factor regulating mating success and subsequent fitness both across and within species, there is widespread interest in how population-wide sex ratio imbalances affect marriage markets and the formation of families in human societies. Although most modern cities have more women than men and suffer from low fertility rates, the effects of female-biased sex ratios have garnered less attention than male-biased ratios. Here, we analyze how sex ratios are linked to marriages, reproductive histories, dispersal, and urbanization by taking advantage of a natural experiment in which an entire population was forcibly displaced during World War II to other local Finnish populations of varying sizes and sex ratios. Using a discrete time-event generalized linear mixed-effects model, and including factors that change across time, such as annual sex ratio, we show how sex ratios, reproduction, and migration are connected in a female-dominated environment. Young childless women migrated toward urban centers where work was available to women, and away from male-biased rural areas. In such areas where there were more females, women were less likely to start reproduction. Despite this constraint, women showed little flexibility in mate choice, with no evidence for an increase in partner age difference in female-biased areas. We propose that together these behaviors and conditions combine to generate an "urban fertility trap" which may have important consequences for our understanding of the fertility dynamics of today including the current fertility decline across the developed world.
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Help is directed towards kin in many cooperative species, but its nature and intensity can vary by context. Humans are one of few species in which grandmothers invest in grandchildren, and this may have served as an important driver of our unusual life history. But helping behaviour is hardly uniform, and insight into the importance of grandmothering in human evolution depends on understanding the contextual expression of helping benefits. Here, we use an eighteenth-nineteenth century pre-industrial genealogical dataset from Finland to investigate whether maternal or paternal grandmother presence (lineage relative to focal individuals) differentially affects two key fitness outcomes of descendants: fertility and survival. We found grandmother presence shortened spacing between births, particularly at younger mother ages and earlier birth orders. Maternal grandmother presence increased the likelihood of focal grandchild survival, regardless of whether grandmothers had grandchildren only through daughters, sons, or both. In contrast, paternal grandmother presence was not associated with descendants' fertility or survival. We discuss these results in terms of current hypotheses for lineage differences in helping outcomes.
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Fertilidad/fisiología , Abuelos/psicología , Conducta de Ayuda , Familia/historia , Femenino , Finlandia/epidemiología , Historia del Siglo XVIII , Historia del Siglo XIX , Humanos , Longevidad/fisiología , Núcleo Familiar , Linaje , Análisis de SupervivenciaRESUMEN
Understanding how conditions experienced during development affect reproductive timing is of considerable cross-disciplinary interest. Life-history theory predicts that organisms will accelerate reproduction when future survival is unsure. In humans, this can be triggered by early exposure to mortality. Previous studies, however, have been inconclusive due to several confounds that are also likely to affect reproduction. Here we take advantage of a natural experiment in which a population is temporarily divided by war to analyze how exposure to mortality affects reproduction. Using records of Finnish women in World War II, we find that young girls serving in a paramilitary organization wait less time to reproduce, have shorter inter-birth intervals, and have more children than their non-serving peers or sisters. These results support the hypothesis that exposure to elevated mortality rates during development can result in accelerated reproductive schedules and adds to our understanding of how participation in warfare affects women.
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Adultos Sobrevivientes de Eventos Adversos Infantiles/psicología , Personal Militar/psicología , Conducta Reproductiva/psicología , Estrés Psicológico/psicología , Exposición a la Guerra , Adolescente , Adulto , Adultos Sobrevivientes de Eventos Adversos Infantiles/estadística & datos numéricos , Factores de Edad , Niño , Femenino , Finlandia/epidemiología , Humanos , Personal Militar/estadística & datos numéricos , Mortalidad , Conducta Reproductiva/estadística & datos numéricos , Hermanos , Factores Socioeconómicos , Factores de Tiempo , Voluntarios/psicología , Voluntarios/estadística & datos numéricos , Segunda Guerra Mundial , Adulto JovenRESUMEN
Understanding how refugees integrate into host societies has broad implications for researchers interested in intergroup conflict and for governments concerned with promoting social cohesion. Using detailed records tracking the movements and life histories of Finnish evacuees during World War II, we find that evacuees who intermarry are more likely to be educated, work in professional occupations, marry someone higher in social status and remain in the host community. Evacuees who intermarry before the war have fewer children, whereas those who marry into their host community after the war have more children. These results indicate that life-history and assimilation outcomes depend on key differences between pre-war environments-when migrants are living in their own communities-and post-war environments-when migrants are living in the host community. Overall, this suggests that integration involves a trade-off between reproduction and status such that evacuees who integrate gain social status, whereas those who maintain stronger bonds with their natal communities have higher fertility. We discuss these results within the framework of social capital, intergroup conflict and life-history theory and suggest how they can inform our understanding of evolutionary adaptations that affect tribalism.
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Tasa de Natalidad , Emigración e Inmigración/estadística & datos numéricos , Procesos de Grupo , Matrimonio/estadística & datos numéricos , Refugiados/estadística & datos numéricos , Capital Social , Clase Social , Adolescente , Adulto , Femenino , Finlandia , Estudios de Seguimiento , Humanos , Masculino , Modelos Estadísticos , Segunda Guerra Mundial , Adulto JovenRESUMEN
Developing sustainable and efficient thermoelectric materials is a challenge because the most common thermoelectric materials are based on rare elements such as bismuth and telluride. In this context, we have produced bio-based carbon nanofibres (CNFs) derived from mixtures of polyacrylonitrile and lignin using electrospinning. The addition of lignin (up to 70%) reduces the diameter of CNFs from 450â¯nm to 250â¯nm, increases sample flexibility, and promotes inter-fibre fusion. The crystalline structure of the CNFs was analysed by Raman spectroscopy. The electrical conductivity and the Seebeck coefficient were evaluated as function of the lignin content in the precursor and carbonised equivalents. Finally, a conversion of p-type to n-type semiconducting behaviour was achieved with a hydrazine vapour treatment. We observe a maximum p-type power factor of 9.27⯵Wâ¯cm-1â¯K-2 for CNFs carbonised at 900⯰C with 70% lignin which is a 34.5-fold increase to the CNFs with 0% lignin. For the hydrazine treated samples, we observe a maximum n-type power factor of 10.2⯵Wâ¯cm-1â¯K-2 for the CNFs produced in the same way which is an 11.0-fold increase to the hydrazine-treated CNFs with 0% lignin.
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Carbono/química , Conductividad Eléctrica , Lignina/química , Nanofibras/química , TemperaturaRESUMEN
INTRODUCTION: Clostridium difficile is the leading cause of health care-associated gastric illness. Environmental contamination with C difficile spores is a risk factor for contact transmission, and toilet flushing causes such contamination. This work explores toilet contamination persistence and environmental contamination produced over a series of flushes after contamination. METHODS: A flushometer toilet was seeded with C difficile spores in a sealed chamber. The toilet was flushed 24times, with postflush bowl water samples and settle plates periodically collected for culturing and counting. Air samples were collected after each of 12 flushes using rotating plate impactors. RESULTS: Spores were present in bowl water even after 24 flushes. Large droplet spore deposition accumulated over the 24-flush period. Droplet nuclei spore bioaerosol was produced over at least 12 flushes. CONCLUSIONS: Toilets contaminated with C difficile spores are a persistent source of environmental contamination over an extended number of flushes.
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Aerosoles/análisis , Aparatos Sanitarios/microbiología , Clostridioides difficile/crecimiento & desarrollo , Contaminación Ambiental/prevención & control , Esporas Bacterianas/crecimiento & desarrollo , Cuartos de Baño/estadística & datos numéricos , Microbiología del Aire , Desinfección/métodos , Humanos , AguaRESUMEN
Because parental care is expected to depend on the fitness returns generated by each unit of investment, it should be sensitive to both offspring condition and parental ability to invest. The Trivers-Willard Hypothesis (TWH) predicts that parents who are in good condition will bias investment towards sons, while parents who are in poor condition will bias investment towards daughters because high-quality sons are expected to out-reproduce high quality daughters, while low-quality daughters are expected to out-reproduce low quality sons. We report results from an online experiment testing the Trivers-Willard effect by measuring implicit and explicit psychological preferences and behaviorally implied preferences for sons or daughters both as a function of their social and economic status and in the aftermath of a priming task designed to make participants feel wealthy or poor. We find only limited support for predictions derived from the TWH and instead find that women have strong preferences for girls and men have preferences for boys.
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Padre/psicología , Modelos Psicológicos , Madres/psicología , Apego a Objetos , Relaciones Padres-Hijo , Sexismo , Adopción , Adulto , Organizaciones de Beneficencia , Comportamiento del Consumidor , Escolaridad , Femenino , Donaciones , Humanos , Renta , Inversiones en Salud , Masculino , Pobreza , Estados UnidosRESUMEN
Marriage in many traditional societies often concerns the institutionalized exchange of reproductive partners among groups of kin. Such exchanges most often involve cross-cousins-marriage with the child of a parent's opposite-sex sibling-but it is unclear who benefits from these exchanges. Here we analyze the fitness consequences of marrying relatives among the Yanomamö from the Amazon. When individuals marry close kin, we find that (i) both husbands and wives have slightly lower fertility; (ii) offspring suffer from inbreeding depression; (iii) parents have more grandchildren; and (iv) siblings, especially brothers, benefit when their opposite-sex siblings marry relatives but not when their same-sex siblings do. Therefore, individuals seem to benefit when their children or opposite-sex siblings marry relatives but suffer costs when they, their parents, or same-sex siblings do. These asymmetric fitness outcomes suggest conflicts between parents and offspring and among siblings over optimal mating strategies. Parental control of marriages is reinforced by cultural norms prescribing cross-cousin marriage. We posit that local mate competition combined with parental control over marriages may escalate conflict between same-sex siblings who compete over mates, while simultaneously forging alliances between opposite-sex siblings. If these relationships are carried forward to subsequent generations, they may drive bilateral cross-cousin marriage rules. This study provides insights into the evolutionary importance of how kinship and reciprocity underlie conflicts over who controls mate choice and the origins of cross-cousin marriage prescriptions.
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Consanguinidad , Familia , Matrimonio , Femenino , Humanos , Masculino , Linaje , HermanosRESUMEN
BACKGROUND: Demonstrating the impact that parents have on the fitness of their children is a crucial step towards understanding how parental investment has affected human evolution. Parents not only transfer genes to their children, they also influence their environments. By analyzing reproductive patterns within and between different categories of close relatives, this study provides insight into the genetic and environmental effects that parents have on the fitness of their offspring. METHODS: We use data spanning over two centuries from an exceptionally accurate Icelandic genealogy, Íslendingabók, to analyze the relationship between the fertility rates of close relatives. Also, using genetic data, we determine narrow sense heritability estimates (h2) to further explore the genetic impact on lifetime reproductive success. Finally, we construct four simulations to model the expected contribution of genes and resources on reproductive success. RESULTS: The relationship between the reproduction of all full sibling pairs was significant and positive across all birth decades (r = 0.19) while the reproductive relationship between parents and offspring was often negative across many decades and undetectable overall (r = 0.00) (Fig. 1 and Table 1). Meanwhile, genetic data among 8,456 pairs of full siblings revealed a narrow sense heritability estimate (h2) of 0.00 for lifetime reproductive success. A resources model (following the rule that resources are transmitted from parents to children, distributed equally among siblings, and are the only factor affecting reproductive success) revealed a similar trend: a negative relationship between parent and offspring reproduction (r = - 0.35) but a positive relationship among full siblings (r = 0.28). The relationship between parent and offspring lifetime reproductive success (LRS) and full sibling LRS was strongly and positively correlated across time (r = 0.799, p < 0.001). Similarly, the LRS among full siblings was positively correlated with both the LRS among half siblings (r = 0.532, p = 0.011) and the relationship between the LRS of aunts and uncles with their nieces and nephews (r = 0.438, p = 0.042). DISCUSSION: We show that an individual's lifetime reproductive success is best predicted by the reproduction of their full and half siblings, but not their parents, grandparents or aunts and uncles. Because all siblings share at least one parent, we believe parental investment has had an important impact on fitness. Overall, these results indicate that direct parental investment, but not genes, is likely to have had an important and persistent impact on lifetime reproductive success across more than two centuries of Icelandic history.
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Toilets contaminated with infectious organisms are a recognized contact disease transmission hazard. Previous studies indicate that toilet bowl water can remain contaminated for several flushes after the contamination occurs. This study characterized contamination persistence over an extended series of flushes using both indicator particles and viable bacteria. For this study, toilets were seeded with microbe-size microbial surrogates and with Pseudomonas fluorescens or Clostridium difficile bacteria and flushed up to 24 times. Bowl water samples collected after seeding and after each flush indicated the clearance per flush and residual bowl water contaminant concentration. Toilets exhibited 3 + log10 contaminant reductions with the first flush, only 1-2 logs with the second flush, and less than 1 log thereafter. Contamination still was present 24 flushes post contamination. Clearance was modeled accurately by a two-stage exponential decay process. This study shows that toilet bowl water will remain contaminated many flushes after initial contamination, posing a risk of recurring environmental contamination and associated infection incidence.
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How to optimally allocate time, energy and investment in an effort to maximize one's reproductive success is a fundamental problem faced by all organisms. This effort is complicated when the production of each additional offspring dilutes the total resources available for parental investment. Although a quantity-quality trade-off between producing and investing in offspring has long been assumed in evolutionary biology, testing it directly in humans is difficult, partly owing to the long generation time of our species. Using data from an Icelandic genealogy (Íslendingabók) over two centuries, I address this issue and analyse the quantity-quality trade-off in humans. I demonstrate that the primary impact of parents on the fitness of their children is the result of resources and or investment, but not genes. This effect changes significantly across time, in response to environmental conditions. Overall, increasing reproduction has negative fitness consequences on offspring, such that each additional sibling reduces an individual's average lifespan and lifetime reproductive success. This analysis provides insights into the evolutionary conflict between producing and investing in children while also shedding light on some of the causes of the demographic transition.
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Elevated fish mercury (Hg) concentrations in freshwater ecosystems worldwide are a significant human and ecological health concern. Mercury bioaccumulation and biomagnification in lakes and reservoirs are controlled by numerous biogeochemical and ecological factors, contributing to variability in fish Hg concentrations both within and among systems. We measured total mercury concentrations ([THg]) and stable isotopes (δ(15)N, δ(13)C) in over 30 fish species in two connected subtropical freshwater reservoirs (Grand Lake and Lake Hudson, Oklahoma, USA), their tributaries, and local farm ponds, all of which are potentially impacted by nearby atmospheric Hg sources. We also conducted an inter-system analysis among 61 reservoirs in Oklahoma to explore biological, chemical and physical factors associated with fish [THg] across systems. We found that [THg] for most species in Grand Lake and Lake Hudson were relatively low compared to other reservoirs in Oklahoma. There were significant spatial variations in many species within and between Grand Lake and Lake Hudson, even after accounting for length and/or trophic position (based on δ(15)N). Fish in local farm ponds, commonly used in agricultural regions for raising game fish, had 2-17 times higher [THg] than fish of a similar length in nearby reservoirs. The inter-system analysis revealed that pH, water color, rainfall, and nutrients are the best predictors of fish [THg] across systems. Our results provide insight into the key factors associated with fish [THg] variations both within and across systems, and may be useful for exposure assessment and for identifying sites and water bodies prone to high fish [THg] as monitoring priorities.
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Monitoreo del Ambiente , Peces/metabolismo , Agua Dulce/análisis , Lagos/química , Mercurio/análisis , Mercurio/metabolismo , Contaminantes Químicos del Agua/análisis , Animales , Ecosistema , Cadena Alimentaria , Humanos , OklahomaRESUMEN
BACKGROUND: Invasive aspergillosis (IA) remains a leading cause of mortality in immunocompromised patients, in part due to the difficulty of diagnosing this infection. METHODS: Using thermal desorption-gas chromatography/mass spectrometry, we characterized the in vitro volatile metabolite profile of Aspergillus fumigatus, the most common cause of IA, and other pathogenic aspergilli. We prospectively collected breath samples from patients with suspected invasive fungal pneumonia from 2011 to 2013, and assessed whether we could discriminate patients with proven or probable IA from patients without aspergillosis, as determined by European Organization for Research and Treatment of Cancer/Mycoses Study Group consensus definitions, by direct detection of fungal volatile metabolites in these breath samples. RESULTS: The monoterpenes camphene, α- and ß-pinene, and limonene, and the sesquiterpene compounds α- and ß-trans-bergamotene were distinctive volatile metabolites of A. fumigatus in vitro, distinguishing it from other pathogenic aspergilli. Of 64 patients with suspected invasive fungal pneumonia based on host risk factors, clinical symptoms, and radiologic findings, 34 were diagnosed with IA, whereas 30 were ultimately diagnosed with other causes of pneumonia, including other invasive mycoses. Detection of α-trans-bergamotene, ß-trans-bergamotene, a ß-vatirenene-like sesquiterpene, or trans-geranylacetone identified IA patients with 94% sensitivity (95% confidence interval [CI], 81%-98%) and 93% specificity (95% CI, 79%-98%). CONCLUSIONS: In patients with suspected fungal pneumonia, an Aspergillus secondary metabolite signature in breath can identify individuals with IA. These results provide proof-of-concept that direct detection of exogenous fungal metabolites in breath can be used as a novel, noninvasive, pathogen-specific approach to identifying the precise microbial cause of pneumonia.
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Aspergilosis/diagnóstico , Aspergilosis/metabolismo , Aspergillus fumigatus/metabolismo , Aspergillus fumigatus/patogenicidad , Adulto , Anciano , Monoterpenos Bicíclicos , Compuestos Bicíclicos con Puentes/análisis , Ciclohexenos/análisis , Femenino , Cromatografía de Gases y Espectrometría de Masas , Humanos , Limoneno , Masculino , Persona de Mediana Edad , Monoterpenos/análisis , Estudios Prospectivos , Sesquiterpenos/análisis , Terpenos/análisisRESUMEN
OBJECTIVES: Ethanol is bactericidal against most pathogens implicated in central line-associated bloodstream infections (CLABSIs) and biofilms. Current Infectious Diseases Society of America guidelines cite insufficient evidence to support adjunctive ethanol-lock therapy (ELT) for central venous catheter (CVC) salvage in patients with CLABSI in combination with systemic antimicrobial treatment. We evaluated the safety and potential efficacy of 70% ELT for CLABSI at our institution after implementation of a hospital ELT protocol. METHODS: We collected data on all patients treated with adjunctive 70% ELT for catheter salvage from September 2009 to September 2011 and assessed clinical outcomes and adverse events associated with ELT. RESULTS: Sixty-eight hospitalized patients received 70% ELT for CVC salvage: 45 (66%) met the criteria for CLABSI. Five (11%) had persistent or recurrent bacteraemia triggering CVC removal; 28 (62%) preserved their CVC long term. There were no documented adverse events associated with ELT. DISCUSSION: Adjunctive 70% ELT is an inexpensive, well-tolerated option for CVC salvage in patients with CLABSI and warrants further investigation.
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Antiinfecciosos Locales/administración & dosificación , Cateterismo Venoso Central/efectos adversos , Catéteres Venosos Centrales/efectos adversos , Etanol/administración & dosificación , Sepsis/etiología , Sepsis/terapia , Adulto , Anciano , Anciano de 80 o más Años , Antiinfecciosos/uso terapéutico , Antiinfecciosos Locales/efectos adversos , Terapia Combinada , Etanol/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sepsis/diagnóstico , Sepsis/prevención & control , Resultado del Tratamiento , Adulto JovenRESUMEN
We propose a three-step model of electrochemical nanopore formation in n-InP in KOH that explains how crystallographically oriented etching can occur even though the rate-determining process (hole generation) occurs only at pore tips. The model shows that competition in kinetics between hole diffusion and electrochemical reaction determines the average diffusion distance of holes along the semiconductor surface and this, in turn, determines whether etching is crystallographic. If the kinetics of reaction are slow relative to diffusion, etching can occur at preferred crystallographic sites within a zone in the vicinity of the pore tip, leading to pore propagation in preferential directions. Symmetrical etching of three {111}A faces forming the pore tip causes it to propagate in the (remaining) [111]A direction. As a pore etches, propagating atomic ledges can meet to form sites that can become new pore tips and this enables branching of pores along any of the [111]A directions. The model explains the observed uniform width of pores and its variation with temperature, carrier concentration and electrolyte concentration. It also explains pore wall thickness, and deviations of pore propagation from the [111]A directions. We believe that the model is generally applicable to electrochemical pore formation in III-V semiconductors.