A prospective, pragmatic non-inferiority study of emergency intubation success with the single-use i-view versus standard reusable video laryngoscope.

INTRODUCTION: Video laryngoscope (VL) technology improves first-pass success. The novel i-view VL device is inexpensive and disposable. We sought to determine the first-pass intubation success with the i-view VL device versus the standard reusable VL systems in routine use at each site. METHODS: We performed a prospective, pragmatic study at two major emergency departments (EDs) when VL was used. We rotated i-view versus reusable VL as the preferred device of the month based on an a priori schedule. An investigator-initiated interim analysis was performed. Our primary outcome was a first-pass success with a non-inferiority margin of 10% based on the per-protocol analysis. RESULTS: There were 93 intubations using the reusable VL devices and 81 intubations using the i-view. Our study was stopped early due to futility in reaching our predetermined non-inferiority margin. Operator and patient characteristics were similar between the two groups. The first-pass success rate for the i-view group was 69.1% compared to 84.3% for the reusable VL group. A non-inferiority analysis indicated that the difference (-15.1%) and corresponding 90% confidence limits (-25.3% to -5.0%) did not fall within the predetermined 10% non-inferiority margin. CONCLUSIONS: The i-view device failed to meet our predetermined non-inferiority margin when compared to the reusable VL systems with the study stopping early due to futility. Significant crossover occurred at the discretion of the intubating operator during the i-view month.

Comparative Analysis of Whole Blood Infusion Effects: Assessing LifeFlow Versus Pressure Bag in a Sus scrofa Model.

BACKGROUND: To improve survival for hemorrhagic shock treatment, guidelines emphasize two patient care priorities: (1) immediate hemorrhage control and (2) early resuscitation with whole blood or blood products. The LifeFlow device is designed to rapidly infuse blood products. However, the effects of using this device compared to pressure-bag systems remain unclear. We hypothesize that there will be no laboratory-measured difference with the blood when infused through the LifeFlow versus the current standard pressure bag system. METHODS: Two units of fresh whole blood were obtained from a sus scrofa model. One unit was "infused" using the LifeFlow with the other unit used as a control through a standard pressure bag system into an empty bag. The "before" measurements were obtained from blood samples from a standard fresh whole blood collection bag. The blood was "infused" into a whole blood bag devoid of storage solution from which the "after" measurements were obtained. RESULTS: This study utilized 22 clinically healthy sus scrofa. Blood units were primarily obtained from a left subclavian central line (50.0%). The median time to acquire and administer a unit of blood was similar for both the LifeFlow device (8.4 min and 8.1 min) and the pressure bag (8.7 min and 7.4 min). No significant differences were found in the total time to acquire or administer blood between the two devices. The median volume of blood acquired was 500 mL for both groups. While no significant differences in blood parameters were observed between the two devices, significant differences were noted when comparing pre- and post-transfusion values within each device. For the LifeFlow device, an increase in hemoglobin and chloride levels and a decrease in thromboplastin time and glucose levels were observed. With the pressure bag, only a decrease in blood urea nitrogen was observed. CONCLUSIONS: In comparing the LifeFlow to the pressure bag, there were no significant differences noted in the total time to acquire or administer a whole unit of blood. However, there were differences with several laboratory parameters of unclear clinical significance.

Characteristics of COVID-19 and mortality-associated factors during the first year of the pandemic in southeast Mexico.

Aim: The present study was designed to evaluate the clinical characteristics of COVID-19 and mortality-associated factors during the first year of the pandemic in patients from southeastern Mexico. Patient & methods: A total of 953 records from patients with COVID-19 were cross-sectionally studied in a primary care hospital in southeast Mexico between 2020 and 2021. Results: The prevalent symptoms were fever (78.6%), cough (80.5%) and headache (82.8%) and dyspnea reached 13.5%. The mortality rate was 7.63% and the clinical variables associated with it were age >60 years, hypertension, severe disease, radiographic pneumonia, days to diagnosis and having two Mayan surnames. Conclusion: Future health strategies should consider age, comorbidities, disease severity, clinical manifestations and possessing ethnicity of risk (i.e., Mayan genetic background).

A prospective assessment of the time required to obtain one unit of fresh whole blood by civilian phlebotomists and Army laboratory technicians (68 K).

BACKGROUND: Resuscitation with blood products improves survival after major hemorrhage. Blood product administration at or near the point-of-injury (POI) amplifies this benefit. Size, weight, and cold-chain management challenges all limit the amount of blood medics can carry. Warm fresh whole blood (WFWB) transfusions from a pre-screened donor within the unit represent an alternative source of blood at the POI. We measured the time required for civilian and Army technicians performing phlebotomy frequently to obtain one unit of blood to serve as a goal metric for combat medics being trained in this skill. METHODS: We gathered demographic and experience data along with proportion of first intravenous cannulation attempt success, time to blood flow initiated, and time to unit draw complete. RESULTS: We prospectively enrolled 12 civilian phlebotomy technicians and 10 Army laboratory technicians performing whole blood collections on 50 and 68 donors respectively. The mean time from setup to needle insertion was 3.7 min for civilians versus 4.2 min for Army technicians. The mean time from blood flowing to the bag being full was 10.7 min versus 8.4 min for civilians versus Army technicians respectively. The mean bag weights were 514 g versus 522 g. First-pass intravenous cannulation success was 96% versus 98% respectively. CONCLUSIONS: We found a high first intravenous cannulation attempt success among both the civilian and Army technicians. Medians times were <5 min to obtain venipuncture and <11 min to obtain one unit. These findings provide time-based benchmarks for potential use during transfusion training among military medics.

A prospective assessment of the medic autologous blood transfusion skills for field transfusion preparation.

BACKGROUND: Data demonstrate the benefit of blood product administration near point-of-injury (POI). Fresh whole blood transfusion from a pre-screened donor provides a source of blood at the POI when resources are constrained. We captured transfusion skills data for medics performing autologous blood transfusion training. METHODS: We conducted a prospective, observational study of medics with varying levels of experience. Inexperienced medics were those with minimal or no reported experience learning the autologous transfusion procedures, versus reported experience among special operations medics. When available, medics were debriefed after the procedure for qualitative feedback. We followed them for up to 7 days for adverse events. RESULTS: The median number of attempts for inexperienced and experienced medics was 1 versus 1 (interquartile range 1-1 for both, p = .260). The inexperienced medics had a slower median time to needle venipuncture access for the donation of 7.3 versus 1.5 min, needle removal after clamping time of 0.3 versus 0.2 min, time to bag preparation of 1.9 versus 1.0 min, time to IV access for reinfusion of 6.0 versus 3.0 min, time to transfusion completion of 17.3 versus 11.0 min, and time to IV removal of 0.9 versus 0.3 min (all p < .05). We noted one administrative safety event in which an allogeneic transfusion occurred. No major adverse events occurred. Qualitative data saturated around the need for quarterly training. CONCLUSIONS: Inexperienced medics have longer procedure times when training autologous whole blood transfusion skills. This data will help establish training measures of performance for skills optimization when learning this procedure.

Expert Consensus Panel Recommendations for Selection of the Optimal Supraglottic Airway Device for Inclusion to the Medic's Aid Bag.

INTRODUCTION: Airway obstruction is the second leading cause of potentially survivable death on the battlefield. The Committee on Tactical Combat Casualty Care (CoTCCC) has evolving recommendations for the optimal supraglottic airway (SGA) device for inclusion to the medics' aid bag. METHODS: We convened an expert consensus panel consisting of a mix of 8 prehospital specialists, emergency medicine experts, and experienced combat medics, with the intent to offer recommendations for optimal SGA selection. Prior to meeting, we independently reviewed previously published studies conducted by our study team, conducted a virtual meeting, and summarized the findings to the panel. The studies included an analysis of end-user after action reviews, a market analysis, engineering testing, and prospective feedback from combat medics. The panel members then made recommendations regarding their top 3 choices of devices including the options of military custom design. Simple descriptive statistics were used to analyze panel recommendations. RESULTS: The preponderance (7/8, 88%) of panel members recommended the gel-cuffed SGA, followed by the self-inflating-cuff SGA (5/8, 62%) and laryngeal tube SGA (5/8, 62%). Panel members expressed concerns primarily related to the (1) devices' tolerance for the military environment, and (2) ability to effectively secure the gel-cuffed SGA and the self-inflating-cuff SGA during transport. CONCLUSIONS: A preponderance of panel members selected the gel-cuff SGA with substantial feedback highlighting the need for military-specific customizations to support the combat environment needs.

Clinical Assessment of Low Calcium In traUMa (CALCIUM).

Major trauma frequently occurs in the deployed, combat setting and is especially applicable in the recent conflicts with explosives dominating the combat wounded. In future near-peer conflicts, we will likely face even more profound weapons including mortars and artillery. As such, the number of severely wounded will likely increase. Hypocalcemia frequently occurs after blood transfusions, secondary to the preservatives in the blood products; however, recent data suggests major trauma in and of itself is a risk factor for hypocalcemia. Calcium is a major ion involved in heart contractility; thus, hypocalcemia can lead to poor contractility. Smaller studies have linked hypocalcemia to worse outcomes, but it remains unclear what causes hypocalcemia and if intervening could potentially save lives. The objective of this study is to determine the incidence of hypocalcemia on hospital arrival and the association with survival. We are seeking to address the following scientific questions, (1) Is hypocalcemia present following traumatic injury prior to transfusion during resuscitation? (2) Does hypocalcemia influence the amount of blood products transfused? (3) To what extent is hypocalcemia further exacerbated by transfusion? (4) What is the relationship between hypocalcemia following traumatic injury and mortality? We will conduct a multicenter, prospective, observational study. We will gather ionized calcium levels at 0, 3, 6, 12, 18, and 24 hours as part of scheduled calcium measurements. This will ensure we have accurate data to assess the early and late effects of hypocalcemia throughout the course of resuscitation and hemorrhage control. These data will be captured by a trained study team at every site. Our findings will inform clinical practice guidelines and optimize the care delivered in the combat and civilian trauma setting. We are seeking 391 patients with complete data to meet our a priori inclusion criteria. Our study will have major immediate short-term findings including risk prediction modeling to assess who is at risk for hypocalcemia, data assessing interventions associated with the incidence of hypocalcemia, and outcome data including mortality and its link to early hypocalcemia.

Simulation-Based Assessment of the Novel, Disposable i-view Video Laryngoscope by Emergency Medicine Physicians.

INTRODUCTION: Airway obstruction is the second leading cause of potentially preventable death on the battlefield. Previous studies demonstrate the most frequent airway intervention is intubation. Currently, the US Army has advanced video laryngoscopy (VL) in its sets, kits, and outfits (SKOs) at a cost of approximately $12,000 and generally only deploys them to the forward resuscitative surgical detachments and field hospitals. The i-view is a disposable video laryngoscope that costs approximately $120. The purpose of this study was to assess operator performance with this device and survey user opinions. METHODS: We conducted a prospective, observational study with emergency medicine residents and attending physicians using a synthetic cadaver model. Placement success, time-to-cannulation, number of attempts, and number and type of complications were recorded, followed by surveys. RESULTS: We enrolled 31 participants. One was missing data and was excluded, leaving 30 for analysis. The median age was 29, most (66%) were male, most were Air Force (57%), in-training residents (77%) with few reporting previous deployment experience (13%). Almost all had real patient experience with both direct (93%) and video laryngoscopy (90%). Most (90%) were able to get a grade 1 view with all achieving airway cannulation on first-pass attempt. The median time to cannulation was 11.6 seconds. On the post-procedure survey, most strongly agreed they would use this in the deployed setting (77%). Most reported they found it easy to use (77%). CONCLUSION: Our simulation-based study demonstrates the device has strong potential use for the clinical setting with all achieving rapid first-pass success for intubation. This study lays the foundation for validation of this device in the clinical setting.

A mixed methods end-user assessment to determine the ideal supraglottic airway device for inclusion into the medic's aid bag.

BACKGROUND: Many advancements in supraglottic airway technology have occurred since the start of the Global War on Terrorism. While the Tactical Combat Casualty Care guidelines previously recommend the i-gel device, this is based on little data and minimal end-user input. OBJECTIVE: We sought to use a mixed methods approach to investigate the properties of an ideal device for inclusion into the medic's aid bag. METHODS: We performed prospective, serial qualitative studies to uncover and articulate themes relative to airway device usability with 68W-combat medics. 68W are trained roughly to the level of a civilian advanced emergency medical technician with a heavier focus on trauma care. Physicians with airway expertise demonstrated the use of each device and provided formal training on all the presented devices. We then administered performed focus groups to solicit end-user feedback along with survey data. RESULTS: We enrolled 250 medics during the study. The preponderance of medics were of the rank E4 (28%) and E5 (44%). Only 35% reported ever placing a supraglottic airway in a real human. When reporting on usability, the i-gel had the highest median score, ease of manipulation, grip comfort and ease of insertion while also scoring the best in regard to requiring minimal training. The other compared devices had no clear highest score. Qualitative data saturated around a strong preference for the BaskaMask and/or the i-gel airway device, with the least favorite being the AirQ and the LMA Fastrach airway devises. There was a strong qualitative alignment in how both the BaskaMask and i-gel provided ease of use and simplicity of training. CONCLUSION: There were strong qualitative preferences for two specific airway devices: Baska Mask and i-gel. However, many medics commented on their previous experience with the i-gel compared with the other devices, which may have biased them toward the i-gel. The overall data suggest that medics would prefer a device engineered with features from several devices. LEVEL OF EVIDENCE: Therapeutic/care management; Level V.

A Prospective, Feasibility Assessment of a Novel, Disposable Video Laryngoscope With Special Operations Medical Personnel in a Mobile Helicopter Simulation Setting.

BACKGROUND: Video laryngoscopy (VL) is shown to improve first-pass success rates and decrease complications in intubations, especially in novice proceduralists. However, the currently fielded VL devices are cost-prohibitive for dispersion across the battlespace. The novel i-view VL is a low-cost, disposable VL device that may serve as a potential solution. We sought to perform end-user performance testing and solicit feedback. METHODS: We prospectively enrolled Special Operations flight medics with the 160th Special Operations Aviation Regiment at Hunter Army Airfield, Savannah, Georgia. We asked them to perform an intubation using a synthetic cadaver model while in a mobile helicopter simulation setting. We surveyed their feedback afterward. RESULTS: The median age of participants was 30 and all were male. Of those, 60% reported previous combat deployments, with a median of 20 months of deployment time. Of the 10, 90% were successful with intubation, with 60% on first-pass success with an average of 83 seconds time to intubation. Most had a grade 1 view. Most agreed or strongly agreed that it was easy to use (70%), with half (50%) reporting they would use it in the deployed setting. Several made comments about the screen not being bright enough and would prefer one with a rotating display. CONCLUSIONS: We found a high proportion of success for intubation in the mobile simulator and a high satisfaction rate for this device by Special Operations Forces medics.

An Assessment of Combat Medic Supraglottic Airway Device Design Needs Using a Qualitative Methods Approach: A Preliminary Analysis.

INTRODUCTION: Airway obstruction is the second leading cause of potentially preventable death on the battlefield during the recent conflicts. Previous studies have noted challenges with enrolling medics using quantitative methods, with specific challenges related to limited prior experience with the devices presented. This limited the ability to truly assess the efficacy of a particular device. We sought to implement a qualitative methods design for supraglottic airway (SGA) device testing. METHODS: We performed prospective, qualitative-designed studies in serial to discover emerging themes on interview. We obtained consent and demographic information from all participants. Medics were presented 2-3 airway devices in the same session with formal training by a physician with airway expertise to include practice application and troubleshooting. Semi-structured interviews were used after the training to obtain end-user feedback with a focus on emerging themes. RESULTS: Of the 77 medics surveyed and interviewed, the median age was 24, and 86% were male. During the interview sessions, we noted five emerging themes: (1) insertion, which pertains to the ease or complexity of using the devise; (2) material, which pertains to the tactile features of the device; (3) versatility, which pertains to the conditions in which the device can be used as well as with which other devices it can be used; (4) portability, which refers to how and where the device is stored and carried; and (5) training, which refers to the ease and frequency of initial and ongoing training to sustain medics' technical capability when using the device. CONCLUSIONS: In our preliminary analysis after enrolling 77 medics, we noted 5 emerging themes focused on insertion material, versatility, portability, and training methodology. Our results will inform the future enrollment sessions with a goal of narrowing the market options from themes to ideal device or devices or modifications needed for the operational environment.

Development of the Defense Registry for Emergency Airway Management (DREAM).

INTRODUCTION: Airway obstruction is the second leading cause of potentially preventable death on the battlefield. Endotracheal intubation is a critical skill needed by emergency military physicians to manage these patients. Our objective is to describe the development of the Defense Registry for Emergency Airway Management (DREAM) at Brooke Army Medical Center (BAMC), a level 1 trauma center over a 7-month period. METHODS: Emergency physicians (EP) performing endotracheal intubations in the BAMC emergency department (ED) completed standardized data collection forms with information about each event. Trained study team members extracted additional data from the medical records. We cross-referenced each intubation with patient tracking systems in the department and would fill in missing variables through interview with the intubating operator and/or medical records review. RESULTS: The study period comprised January through July 2020. During the study period emergency physicians (EP) performed a total of 74 intubations. Reasons for intubation were related to trauma for 47 patients (64%) and medical conditions for 26 patients (36%). The median age was 51 (interquartile range 30-72) and most were male 48 (65.7%). Difficult airway characteristics encountered included blood in the airway (26%), facial trauma (23%), and airway obstruction (1%). Most intubations utilized video laryngoscopy, and the most frequently used airway devices were Macintosh-shaped (45%) and hyperangulated-shaped (41%). Overall, firstpass success rate was 93% (69) with majority of intubations performed by second-year emergency residents (61%) followed by first-year residents (28%). CONCLUSIONS: Most DREAM intubations were related to traumatic injuries. The most frequently encountered difficult airway characteristics were blood in airway and facial trauma. Most intubations were conducted using video laryngoscopy with a high first-pass success rate similar to other published studies. Expansion of the registry to other military emergency departments would enable a data-driven solution for development of individual critical task lists.

Morfología cefalométrica de la sínfisis del mentón en individuos jóvenes de la ciudad de Quito-Ecuador / Cephalometric morphology of chin symphysis in young individuals from the city of Quito-Ecuador

Resumen Introducción: La sínfisis del mentón aporta equilibrio, simetría y armonía al rostro. Por ser una estructura anatómica mandibular muy importante y altamente modificable en cirugía estética, se considera indispensable conocer su morfología y así obtener una correcta interacción en el diagnóstico, pronóstico y terapéutica médico-odontológica. Objetivo: Determinar la morfología sínfisis del mentón en jóvenes adultos de la ciudad de Quito- Ecuador, año 2019, mediante la identificación de las longitudes sagitales y coronales. Metodología: Este estudio tuvo un enfoque cuantitativo, tipo descriptivo-observacional, con temporalidad retrospectiva. Se calibraron, analizaron y trazaron 384 radiografías digitales laterales de adultos jóvenes de la ciudad de Quito-Ecuador, año 2019 en el software AutoCAD-2019. Resultados: Existió una elevada frecuencia de la forma geométrica cuadrada (60%) con respecto a la rectangular (40%), adicionalmente se identificó que la figura cuadrada es más frecuente en individuos de sexo femenino y sujetos clase I (56%) y II (70%), además de todos los patrones de crecimiento vertical hipodivergentes (58%), normodivergentes (64%) e hiperdivergentes (57%). Conclusiones: La forma cuadrada de la sínfisis del mentón es mayor que la forma rectangular. Por la originalidad de los resultados, se sugiere realizar nuevos estudios que correlacionen la morfología mentoniana con las diferentes estructuras cráneo-maxilofaciales.

Abstract Introduction: The chin symphysis contributes to the balance, symmetry and harmony of the face. Since it is an important anatomical jaw structure and highly modifiable in aesthetic surgery, it is considered crucial to know its morphology and, thus, obtain a correct interaction in the diagnosis, prognosis and medical-dental therapy. Objective: To determine the symphysis morphology of the chin in young adults in the city of Quito, Ecuador, in the year 2019, through the identification of sagittal and coronal lengths. Methodology: This study had a quantitative approach, descriptive-observational type, with retrospective temporality. We calibrated, analyzed and plotted 384 lateral digital radiographs of young adults from the city of Quito-Ecuador, year 2019 in the software AutoCAD-2019. Results: There was a high frequency of the square geometric shape (60%) in comparison to the rectangular one (40%). Additionally, it was identified that the square figure is more frequent in female individuals and class I (56%) and II (70%) subjects, in addition to all the hypodivergent (58%), normodivergent (64%) and hyperdivergent (57%) vertical growth patterns. Conclusions: The square shape of the chin symphysis is larger than the rectangular shape. Due to the originality of the results, it is suggested to carry out new studies that correlate chin morphology with the different cranio-maxillofacial structures.

Home-Based Palliative Care and Its Influence on Quality of Life in Patients With a Life-Limiting Condition.

The need for comprehensive palliative care is inevitable with the aging population. Incorporating home-based palliative care is a new frontier within healthcare. The purpose of this study was to embed home-based palliative care services within the visiting nursing association (VNA) at a health system in Pennsylvania, examining effect on quality of life and symptom control, and average number of hospital admission days. A convenience sample of patients with one or more chronic conditions was selected from the existing VNA census (n = 22). A series of topics were outlined for discussion at each weekly visit for the pilot length of up to 6 months, scripted by evidence-based guidelines from the ENABLE II: Charting Your Course booklet (). A pretest/posttest survey method was conducted by utilizing results of the Edmonton Symptom Assessment System (ESAS) and the National Comprehensive Cancer Network Distress Thermometer. The effectiveness of the program was assessed using Spearman correlation to compare the difference in scores to the number of weeks in the program. The average number of hospital admission days during the pilot period was compared with admission days 6 months before enrollment in the pilot using the Wilcoxon signed-rank test. A significant relationship was found between the number of weeks in the program and reduction in the total ESAS symptom scores (rho = -0.484, p = .022), indicating that a reduction in symptoms was significantly more likely the longer a patient was in the program. Percentage of patients hospitalized decreased from 86% during preintervention period to 32% while enrolled. There was a noted reduction in the average number of days patients spent in the hospital while enrolled in the pilot (z = -2.24, p = 0.025).

In Vivo Bioluminescent Imaging of Yersinia ruckeri Pathogenesis in Fish.

Bioluminescent reporters and advanced luciferase technologies are useful to study host-pathogen interactions. This chapter describes the use of the luxCDABE operon from Photorhabdus luminescens as a tool to analyze the progression of the fish pathogen Yersinia ruckeri during the infection of rainbow trout, as well as the quantification of promoter activity of specific bacterial genes during host colonization.

Changes in physiology and virulence during the selection of resistant Yersinia ruckeri mutants under subinhibitory cefotaxime concentrations.

Bacterial antibiotic resistance is one of the main healthcare problems currently. Apart from reducing antibiotic efficacy, it has awakened the interest of scientists due to its association with bacterial fitness and virulence. Interestingly, antibiotic resistance can be a source of both increased fitness and decreased fitness, even though the molecular basis of these relationships remains unknown. The aim of this work is to define the effects of sub-MIC concentrations of cefotaxime, an antibiotic extensively used in clinical practice, on the physiology and virulence of Yersinia ruckeri and to determine the importance of these sub-MIC concentrations for the selection of antibiotic-resistant mutants in the aquatic environment. Results indicated that exposure to sub-MIC concentrations of cefotaxime selected Y. ruckeri populations with irreversible alterations in the physiology, such as slow growth, aggregation in liquid cultures and modification of the colony morphology. These bacteria also displayed changes in the OMPs and LPS profiles and a full attenuation of virulence. An overexpression of the envelope stress regulator RpoE was also detected after exposure to the antibiotic. In conclusion, exposure to cefotaxime selected, at high frequency, Y. ruckeri strains that survive the antibiotic stress at the expense of a fitness cost and the loss of virulence.

The Infection Process of Yersinia ruckeri: Reviewing the Pieces of the Jigsaw Puzzle.

Finding the keys to understanding the infectious process of Yersinia ruckeri was not a priority for many years due to the prompt development of an effective biotype 1 vaccine which was used mainly in Europe and USA. However, the gradual emergence of outbreaks in vaccinated fish, which have been reported since 2003, has awakened interest in the mechanism of virulence in this pathogen. Thus, during the last two decades, a large number of studies have considerably enriched our knowledge of many aspects of the pathogen and its interaction with the host. By means of both conventional and a variety of novel strategies, such as cell GFP tagging, bioluminescence imaging and optical projection tomography, it has been possible to determine three putative Y. ruckeri infection routes, the main point of entry for the bacterium being the gill lamellae. Moreover, a wide range of potential virulence factors have been highlighted by specific gene mutagenesis strategies or genome-wide transposon/plasmid insertion-based screening approaches, such us in vivo expression technology (IVET) and signature tagged mutagenesis (STM). Finally, recent proteomic and whole genomic analyses have allowed many of the genes and systems that are potentially implicated in the organism's pathogenicity and its adaptation to the host environmental conditions to be elucidated. Altogether, these studies contribute to a better understanding of the infectious process of Y. ruckeri in fish, which is crucial for the development of more effective strategies for preventing or treating enteric redmouth disease (ERM).

Temperature-Dependent Gene Expression in Yersinia ruckeri: Tracking Specific Genes by Bioluminescence During in Vivo Colonization.

Yersinia ruckeri is a bacterium causing fish infection processes at temperatures below the optimum for growth. A derivative Tn5 transposon was used to construct a library of Y. ruckeri mutants with transcriptional fusions between the interrupted genes and the promoterless luxCDABE and lacZY operons. In vitro analysis of ß-galactosidase activity allowed the identification of 168 clones having higher expression at 18°C than at 28°C. Among the interrupted genes a SAM-dependent methyltransferase, a diguanylated cyclase, three genes involved in legionaminic acid synthesis and three transcriptional regulators were defined. In order to determine, via bioluminescence emission, the in vivo expression of some of these genes, two of the selected mutants were studied. In one of them, the acrR gene coding a repressor involved in regulation of the AcrAB-TolC expulsion pump was interrupted. This mutant was found to be highly resistant to compounds such as chloramphenicol, tetracycline, and ciprofloxacin. Although acrR mutation was not related to virulence in Y. ruckeri, this mutant was useful to analyze acrR expression in fish tissues in vivo. The other gene studied was osmY which is activated under osmotic stress and is involved in virulence. In this case, complemented mutant was used for experiments with fish. In vivo analysis of bioluminescence emission by these two strains showed higher values for acrR in gut, liver and adipose tissue, whereas osmY showed higher luminescence in gut and, at the end of the infection process, in muscle tissue. Similar results were obtained in ex vivo assays using rainbow trout tissues. The results indicated that this kind of approach was useful for the identification of genes related to virulence in Y. ruckeri and also for the in vivo and in vitro studies of each of the selected genes.

Repeatability of the infant food reinforcement paradigm: Implications of individual and developmental differences.

The relative reinforcing value of food versus engagement in other behaviors may be related to the development of obesity, and interventions to reduce FRR may prevent the development of obesity. Our laboratory recently developed a paradigm to measure the reinforcing value of food versus an alternative behavior (i.e., playing with bubbles) in infants using a computerized laboratory task, during which infants press a button to earn reinforcers following a progressive ratio schedule of reinforcement. The primary purpose of this study was to examine the short-term (within 2 weeks) repeatability of this measure, specifically the outcome of infant food reinforcing ratio (FRR), or how hard infants will work for food relative to the alternative. The secondary aim was to examine whether infant age and temperament dimensions related to novelty responsiveness (high intensity pleasure and approach) moderated the repeatability of FRR. Thirty-seven infants aged 9-18 months completed this study. Repeated measures analysis of variance (ANOVA) showed no differences between time 1 and time 2 in responding for food (F = 0.463, p = 0.501), bubbles (F = 1.793, p = 0.189), or overall FRR (F = 0.797, p = 0.378). Regression models showed the association between BUB Pmax at time 1 and time 2 were moderated by infant age (p = 0.04), with greater repeatability in older infants. Linear regression models also demonstrated that the infant temperamental dimension of high intensity pleasure significantly predicted BUB Pmax at time 1 (ß = 2.89, p = 0.01), but not at time 2. Overall, our findings support the repeatability of this measure for food portion of the reinforcement task, but demonstrated that the measure of non-food portion of the task required modification, in particular among children younger than 13 months old.

Comparative genome analysis reveals important genetic differences among serotype O1 and serotype O2 strains of Y. ruckeri and provides insights into host adaptation and virulence.

Despite the existence of a commercial vaccine routinely used to protect salmonids against Yersinia ruckeri, outbreaks still occur, mainly caused by nonmotile and lipase-negative strains (serotype O1 biotype 2). Moreover, epizootics caused by other uncommon serotypes have also been reported. At the moment, one of the main concerns for the aquaculture industry is the expanding range of hosts of this pathogen and the emergence of new biotypes and serotypes causing mortality in fish farms and against which the vaccine cannot protect. The comparative analysis of the genome sequences of five Y. ruckeri strains (150, CSF007-82, ATCC29473, Big Creek 74, and SC09) isolated from different hosts and classified into different serotypes revealed important genetic differences between the genomes analyzed. Thus, a clear genetic differentiation was found between serotype O1 and O2 strains. The presence of 99 unique genes in Big Creek 74 and 261 in SC09 could explain the adaptation of these strains to salmon and catfish, respectively. Finally, the absence of 21 genes in ATCC29473 which are present in the other four virulent strains could underpin the attenuation described for this strain. The study reveals important genetic differences among the genomes analyzed. Further investigation of the genes highlighted in this study could provide insights into the understanding of the virulence and niche adaptive mechanisms of Y. ruckeri.