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Trastornos Psicofisiológicos/psicología , Enfermedades de la Piel/psicología , Enfermedades de la Piel/terapia , Encuestas y Cuestionarios/estadística & datos numéricos , Adulto , Anciano , Actitud del Personal de Salud , Delirio de Parasitosis/psicología , Delirio de Parasitosis/terapia , Dermatología/educación , Dermatología/estadística & datos numéricos , Medicina Familiar y Comunitaria/educación , Medicina Familiar y Comunitaria/estadística & datos numéricos , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Masculino , Persona de Mediana Edad , Preceptoría/métodos , Psiquiatría/educación , Psiquiatría/estadística & datos numéricos , Trastornos Psicofisiológicos/diagnóstico , Trastornos Psicofisiológicos/terapia , Enfermedades de la Piel/diagnóstico , Tricotilomanía/psicología , Tricotilomanía/terapiaRESUMEN
OBJECTIVE: African American Women (AAW) are disproportionately impacted by both physical inactivity and asthma. The aims of this study were to: 1) understand barriers to physical activity among AAW with asthma; 2) obtain feedback from AAW on an evidence-based walking intervention; and 3) modify the intervention using input from AAW with asthma. METHODS: Focus groups and interviews were conducted with sedentary AAW with uncontrolled asthma to identify barriers to walking. Women also suggestions for tailoring an existing walking intervention. Qualitative data were coded using domains from the Behavior Change Wheel and guided modifications of the existing walking intervention to tailor the content for sedentary AAW with asthma. RESULTS: Six focus groups (2-4 /group) and five interviews were completed. Women (n=20) represented an obese (37 kg/m2 ± 11), middle-aged (46 years ± 15) and low-income population. Barriers to physical activity were mapped to 8 theoretical domains: 1) Limited physical capability; 2) Lack of knowledge; 3) Lack of self-monitoring skills; 4) Complex decision making processes; 5) Lack of areas to walk; 6) Lack of social support; 7) Beliefs about consequences; 8) Beliefs about capability. To target these barriers, the existing walking intervention was modified to include an asthma education session, text messages, monthly group meetings, a walking session and informational materials. CONCLUSION: AAW with asthma reported unique barriers to engaging in physical activity. An assessment of the feasibility, acceptability and efficacy of a modified intervention that addresses these barriers is warranted to address physical inactivity and poor asthma outcomes among AAW with asthma.
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PURPOSE: To explore how students use and benefit from virtual patient cases (VPCs). METHOD: In academic years 2013-2014 and 2014-2015, cohorts of students in pediatrics (Peds), family medicine (FM), and internal medicine (IM) clerkships were allocated to either core required use (CRU) or self-directed use (SU) of MedU VPCs. Outcomes included number and time of case review, student perception of learning from VPCs, National Board of Medical Examiners (NBME) subject examination scores, and summative clinical ratings for medical knowledge and differential diagnoses/problem solving. Focus groups were conducted each year. Mean differences were compared by t test. RESULTS: A total of 255 students participated in the study. Mean number of cases completed by the CRU group was significantly higher than that by the SU group (13.9 vs. 3.1 for FM, 16.1 vs. 3.9 for Peds, and 10.4 vs. 1.2 for IM) (P < .001). Student-perceived value ratings of VPCs were similar between groups. Students described VPCs as time consuming but useful for supplementing clinical conditions not seen in person. Mean scores on NBME subject examinations for CRU versus SU groups were not different between groups in any clerkship, nor were there significant differences in the summative clinical ratings for medical knowledge or differential diagnosis/clinical reasoning. CONCLUSIONS: Although VPCs continue to serve an important role in exposing students to clinical conditions not seen in person, the optimal employment of this technology in clerkship pedagogy requires further exploration.
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Prácticas Clínicas/métodos , Medicina Familiar y Comunitaria/educación , Medicina Interna/educación , Estudiantes de Medicina/estadística & datos numéricos , Realidad Virtual , Adulto , Competencia Clínica , Evaluación Educacional , Femenino , Grupos Focales , Humanos , MasculinoRESUMEN
OBJECTIVES: The purpose of this study was to investigate the relationship between operator volume and implantable defibrillator lead failure and patient mortality at a single large implanting center. METHODS: This study analyzed the differences between high-volume and low-volume defibrillator implanters in the Pacemaker and Implantable Defibrillator Lead Survival Study ("PAIDLESS") between February 1, 1996 and December 31, 2011 at NYU Winthrop Hospital. "High-volume" was defined as performing ≥500 implants over the study period, while "low-volume" was defined as performing <500 implants. Comparisons between the procedure volume groups were performed using Fisher's Exact test, Wilcoxon rank-sum test, and Kaplan-Meier analysis as appropriate. RESULTS: Eight operators participated in the study, four of whom were high-volume operators. Of 3801 patients, a total of 3149 (83%) were operated upon by high-volume operators. Low-volume operators implanted fewer recalled leads (12% vs 42%; P<.001) and more often obtained venous access through the cephalic vein cutdown approach (63% vs 38%; P<.001) than high-volume operators. Kaplan-Meier analysis revealed shorter time to lead failure in the low-volume group (P=.02). Time to mortality was not significantly different between the high-volume and low-volume groups (P=.18). When adjusted for lead recall status, patients of high-volume operators were 43% less likely to experience lead failure compared to patients of low-volume operators. CONCLUSIONS: High-volume defibrillator implanters selected a higher percentage of recalled leads, but their patients were less likely to encounter lead failure when adjusted for lead recall status compared to low-volume operators.
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Desfibriladores Implantables , Cardioversión Eléctrica , Fibrilación Ventricular , Adulto , Anciano , Desfibriladores Implantables/efectos adversos , Desfibriladores Implantables/normas , Cardioversión Eléctrica/efectos adversos , Cardioversión Eléctrica/instrumentación , Cardioversión Eléctrica/métodos , Diseño de Equipo/métodos , Diseño de Equipo/normas , Falla de Equipo/estadística & datos numéricos , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Recall de Suministro Médico , Persona de Mediana Edad , Evaluación de Procesos y Resultados en Atención de Salud , Estados Unidos , Fibrilación Ventricular/mortalidad , Fibrilación Ventricular/prevención & controlRESUMEN
BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most common form of childhood leukemia. The treatment of ALL involves multimodality therapy, and methotrexate (MTX) remains a mainstay of treatment. A complication of MTX therapy includes acute, subacute, and chronic neurotoxocity. Signs and symptoms may range from headaches, dizziness, and mood disorders to seizures and stroke-like symptoms. CASE REPORT: An 18-year-old woman with a history of ALL presented to the emergency department with acute onset of right-sided facial paralysis, right upper extremity flaccid paralysis, and right lower extremity weakness after receiving MTX therapy 3 days earlier. Diagnostic studies were unremarkable and the patient was treated with oral dextromethorphan for presumed MTX-induced neurotoxicity. The patient's symptoms began to improve within hours and she was discharged home within 48 hours with no neurologic deficits. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should be aware of this complication of MTX therapy given the sensitivity in regards to time with respect to cerebral vascular accidents. An awareness of this complication in the setting of the appropriate history and physical examination can lead to an accurate diagnosis and intervention and the avoidance of administering thrombolytics.
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Metotrexato/toxicidad , Síndromes de Neurotoxicidad/etiología , Accidente Cerebrovascular/diagnóstico , Adolescente , Antimetabolitos Antineoplásicos/farmacología , Antimetabolitos Antineoplásicos/uso terapéutico , Terapia Combinada/métodos , Dextrometorfano/farmacología , Dextrometorfano/uso terapéutico , Servicio de Urgencia en Hospital/organización & administración , Antagonistas de Aminoácidos Excitadores/farmacología , Antagonistas de Aminoácidos Excitadores/uso terapéutico , Parálisis Facial/etiología , Femenino , Humanos , Extremidad Inferior/inervación , Extremidad Inferior/fisiopatología , Metotrexato/farmacología , Metotrexato/uso terapéutico , Hipotonía Muscular/etiología , Debilidad Muscular/etiología , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Extremidad Superior/inervación , Extremidad Superior/fisiopatologíaRESUMEN
OBJECTIVES: The purpose of this study was to determine if implantation of multiple recalled defibrillator leads is associated with an increased risk of lead failure. BACKGROUND: The authors of the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS") have previously reported a relationship between recalled lead status, lead failure, and patient mortality. This substudy analyzes the relationship in a smaller subset of patients who received more than one recalled lead. The specific effects of having one or more recalled leads have not been previously examined. METHODS: This study analyzed lead failure and mortality of 3802 patients in PAIDLESS and compared outcomes with respect to the number of recalled leads received. PAIDLESS includes all patients at Winthrop University Hospital who underwent defibrillator lead implantation between February 1, 1996 and December 31, 2011. Patients with no recalled ICD leads, one recalled ICD lead, and two recalled ICD leads were compared using the Kaplan-Meier method and log-rank test. Sidak adjustment method was used to correct for multiple comparisons. All calculations were performed using SAS 9.4. P-values <.05 were considered statistically significant. RESULTS: This study included 4078 total ICD leads implanted during the trial period. There were 2400 leads (59%) in the no recalled leads category, 1620 leads (40%) in the one recalled lead category, and 58 leads (1%) in the two recalled leads category. No patient received more than two recalled leads. Of the leads categorized in the two recalled leads group, 12 experienced lead failures (21%), which was significantly higher (P<.001) than in the no recalled leads group (60 failures, 2.5%) and one recalled lead group (81 failures; 5%). Multivariable Cox's regression analysis found a total of six significant predictive variables for lead failure including the number of recalled leads (P<.001 for one and two recalled leads group). CONCLUSIONS: The number of recalled leads is highly predictive of lead failure. Lead-based multivariable Cox's regression analysis produced a total of six predictive variable categories for lead failure, one of which was the number of recalled leads. Kaplan-Meier analysis showed that the leads in the two recalled leads category failed faster than both the no recalled lead and one recalled lead groups. The greater the number of recalled leads to which patients are exposed, the greater the risk of lead failure.
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Desfibriladores Implantables , Cardioversión Eléctrica , Falla de Equipo/estadística & datos numéricos , Recall de Suministro Médico , Marcapaso Artificial , Anciano , Desfibriladores Implantables/efectos adversos , Desfibriladores Implantables/clasificación , Desfibriladores Implantables/estadística & datos numéricos , Cardioversión Eléctrica/efectos adversos , Cardioversión Eléctrica/instrumentación , Cardioversión Eléctrica/métodos , Diseño de Equipo , Análisis de Falla de Equipo/métodos , Análisis de Falla de Equipo/estadística & datos numéricos , Femenino , Cardiopatías/terapia , Humanos , Masculino , Persona de Mediana Edad , Marcapaso Artificial/efectos adversos , Marcapaso Artificial/clasificación , Marcapaso Artificial/estadística & datos numéricos , Estados UnidosRESUMEN
OBJECTIVES: The purpose of this study was to investigate the influences of gender and age on defibrillator lead failure and patient mortality. BACKGROUND: The specific influences of gender and age on defibrillator lead failure have not previously been investigated. METHODS: This study analyzed the differences in gender and age in relation to defibrillator lead failure and mortality of patients in the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS"). PAIDLESS includes all patients at Winthrop University Hospital who underwent defibrillator lead implantation between February 1, 1996 and December 31, 2011. Male and female patients were compared within each age decile, beginning at 15 years old, to analyze lead failure and patient mortality. Statistical analyses were performed using Wilcoxon rank-sum test, Fisher's exact test, Kaplan-Meier analysis, and multivariable Cox regression models. P<.05 was considered statistically significant. No correction for multiple comparisons was performed for the subgroup analyses. RESULTS: A total of 3802 patients (2812 men and 990 women) were included in the analysis. The mean age was 70 ± 13 years (range, 15-94 years). Kaplan-Meier analysis found that between 45 and 54 years of age, leads implanted in women failed significantly faster than in men (P=.03). Multivariable Cox regression models were built to validate this finding, and they confirmed that male gender was an independent protective factor of lead failure in the 45 to 54 years group (for male gender: HR, 0.37; 95% confidence interval, 0.14-0.96; P=.04). Lead survival time for women in this age group was 13.4 years (standard error, 0.6), while leads implanted in men of this age group survived 14.7 years (standard error, 0.3). Although there were significant differences in lead failure, no differences in mortality between the genders were found for any ages or within each decile. CONCLUSIONS: This study is the first to compare defibrillator lead failure and patient mortality in relation to gender and age deciles at a single large implanting center. Within the 45 to 54 years group, leads implanted in women failed faster than in men. Male gender was found to be an independent protective factor in lead survival. This study emphasizes the complex interplay between gender and age with respect to implantable defibrillator lead failure and mortality.
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Desfibriladores Implantables , Cardiopatías/mortalidad , Cardiopatías/terapia , Marcapaso Artificial , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Diseño de Equipo , Falla de Equipo , Femenino , Estudios de Seguimiento , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Estudios Retrospectivos , Factores Sexuales , Tasa de Supervivencia/tendencias , Estados Unidos/epidemiología , Adulto JovenRESUMEN
OBJECTIVES: The purpose of the study was to examine survival in the implantable defibrillator subset of implanted leads at a large-volume implanting hospital. BACKGROUND: Implantable lead survival has been the subject of many multicenter studies over the past decade. Fewer large implanting volume single-hospital studies have examined defibrillator lead failure as it relates to patient survival and lead construction. METHODS: This investigator-initiated retrospective study examined defibrillator lead failure in those who underwent implantation of a defibrillator between February 1, 1996 and December 31, 2011. Lead failure was defined as: failure to capture/sense, abnormal pacing and/or defibrillator impedance, visual insulation defect or lead fracture, extracardiac stimulation, cardiac perforation, tricuspid valve entrapment, lead tip fracture and/or lead dislodgment. Patient characteristics, implant approach, lead manufacturers, lead models, recalled status, patient mortality, and core lead design elements were compared using methods that include Kaplan Meier analysis, univariate and multivariable Cox regression models. RESULTS: A total of 4078 defibrillator leads were implanted in 3802 patients (74% male; n = 2812) with a mean age of 70 ± 13 years at Winthrop University Hospital. Lead manufacturers included: Medtronic: [n = 1834; 801 recalled]; St. Jude Medical: [n = 1707; 703 recalled]; Boston Scientific: [n = 537; 0 recalled]. Kaplan-Meier analysis adjusted for multiple comparisons revealed that both Boston Scientific's and St. Jude Medical's leads had better survival than Medtronic's leads (P<.001 and P=.01, respectively). Lead survival was comparable between Boston Scientific and St. Jude Medical (P=.80). A total of 153 leads failed (3.5% of all leads) during the study. There were 99 lead failures from Medtronic (5.4% failure rate); 56 were recalled Sprint Fidelis leads. There were 36 lead failures from St. Jude (2.1% failure rate); 20 were recalled Riata or Riata ST leads. There were 18 lead failures from Boston Scientific (3.35% failure rate); none were recalled. Kaplan Meier analysis also showed lead failure occurred sooner in the recalled leads (P=.01). A total of 1493 patients died during the study (mechanism of death was largely unknown). There was a significant increase in mortality in the recalled lead group as compared with non-recalled leads (P=.01), but no significant difference in survival when comparing recalled leads from Medtronic with St. Jude Medical (P=.67). A multivariable Cox regression model revealed younger age, history of percutaneous coronary intervention, baseline rhythm other than atrial fibrillation or atrial flutter, combination polyurethane and silicone lead insulation, a second defibrillation coil, and recalled lead status all contributed to lead failure. CONCLUSION: This study demonstrated a significantly improved lead performance in the Boston Scientific and St. Jude leads as compared with Medtronic leads. Some lead construction variables (insulation and number of coils) also had a significant impact on lead failure, which was independent of the manufacturer. Recalled St. Jude leads performed better than recalled Medtronic leads in our study. Recalled St. Jude leads had no significant difference in lead failure when compared with the other manufacturer's non-recalled leads. Defibrillator recalled lead status was associated with an increased mortality as compared with non-recalled leads. This correlation was independent of the lead manufacturer and clinically significant even when considering known mortality risk factors. These results must be tempered by the largely unknown mechanism of death in these patients.
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Arritmias Cardíacas/terapia , Desfibriladores Implantables/efectos adversos , Recall de Suministro Médico , Diseño de Prótesis/instrumentación , Falla de Prótesis , Factores de Edad , Anciano , Arritmias Cardíacas/mortalidad , Desfibriladores Implantables/estadística & datos numéricos , Femenino , Estudios de Seguimiento , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Análisis Multivariante , Ensayos Clínicos Controlados no Aleatorios como Asunto , Marcapaso Artificial , Estudios RetrospectivosRESUMEN
The match-play demands of rugby union have increased over time, and these demands should be quantified so as to provide a basis for optimal player loading during training. The primary aim of this article was to quantify accelerations, decelerations, impacts and aggregated body demands during the first half of match-play in a Super Rugby team. The secondary aim was to determine whether these characteristics are position-specific. Thirty-three players were monitored for 14 matches using global positioning system units with inbuilt microtechnology. Players were grouped according to positional roles and data were analysed for those who completed the entire duration of the first half of a given match. Forwards sustained more (d = 0.44) high-intensity impacts and greater (d = 0.26) aggregated body demands, while backs had more moderate (d = 0.55) and heavy accelerations (d = 0.76), and moderate (d = 0.23) and heavy decelerations (d = 0.54). These differences suggest that conditioning and recovery strategies should reflect the physical demands placed on players in different playing positions. Forwards should be conditioned with a focus on impacts and require longer recovery for the same duration of playing time, whereas conditioning for backs should emphasise rapid accelerations and decelerations.
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Rendimiento Atlético/fisiología , Conducta Competitiva/fisiología , Fútbol/fisiología , Aceleración , Adulto , Sistemas de Información Geográfica , Humanos , Masculino , Destreza Motora/fisiología , Educación y Entrenamiento Físico , Estaciones del Año , Estudios de Tiempo y Movimiento , Adulto JovenRESUMEN
Using dual-frequency ultrasound (DFU), microbubbles (<10 µm diameter) have been detected in tissue following decompression. It is not known if these microbubbles are the precursors for B-mode ultrasound-detectable venous gas emboli (bmdVGE). The purpose of this study was to determine if microbubbles could be detected intravascularly postdecompression and to investigate the temporal relationship between microbubbles and larger bmdVGE. Anesthetized swine (n = 15) were exposed to 4.0-4.5 ATA for 2 h, followed by decompression to 0.98 ATA. Microbubble presence and VGE grade were measured using DFU and B-mode ultrasound, respectively, before and for 1 h postdecompression, approximately every 4-5 min. Microbubbles appeared in the bloodstream postdecompression, both in the presence and absence of bmdVGE. In swine without bmdVGE, microbubbles remained elevated for the entire 60-min postdecompression period. In swine with bmdVGE, microbubble signals were detected initially but then returned to baseline. Microbubbles were not detected with the sham dive. Mean bmdVGE grade increased over the length of the postdecompression data collection period. Comparison of the two response curves revealed significant differences at 5 and 10 min postdecompression, indicating that microbubbles preceded bmdVGE. These findings indicate that decompression-induced microbubbles can 1) be detected intravascularly at multiple sites, 2) appear in the presence and absence of bmdVGE, and 3) occur before bmdVGE. This supports the hypothesis that microbubbles precede larger VGE bubbles. Microbubble presence may be an early marker of decompression stress. Since DFU is a low-power ultrasonic method, it may be useful for operational diving applications.
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Enfermedad de Descompresión/diagnóstico por imagen , Embolia Aérea/diagnóstico por imagen , Microburbujas , Animales , Medios de Contraste , Enfermedad de Descompresión/sangre , Modelos Animales de Enfermedad , Diagnóstico Precoz , Embolia Aérea/sangre , Fluorocarburos , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Índice de Severidad de la Enfermedad , Porcinos , Factores de Tiempo , UltrasonografíaRESUMEN
BACKGROUND: Preclinical models show that an antiangiogenic regimen at low-dose daily (metronomic) dosing may be effective against chemotherapy-resistant tumors. We undertook a prospective, open-label, single-arm, multi-institutional phase II study to evaluate the efficacy of a "5-drug" oral regimen in children with recurrent or progressive cancer. PROCEDURE: Patients ≤21 years old with recurrent or progressive tumors were eligible. Treatment consisted of continuous oral celecoxib, thalidomide, and fenofibrate, with alternating 21-day cycles of low-dose cyclophosphamide and etoposide. Primary endpoint was to assess, within eight disease strata, activity of the 5-drug regimen over 27 weeks. Blood and urine angiogenesis markers were assessed. RESULTS: One hundred one patients were enrolled; 97 began treatment. Median age was 10 years (range: 191 days-21 years); 47 (49%) were female. Disease strata included high-grade glioma (HGG, 21 patients), ependymoma (19), low-grade glioma (LGG, 12), bone tumors (12), medulloblastoma/primitive neuroectodermal tumor (PNET, 8), leukemia (4), neuroblastoma (3), and miscellaneous tumors (18). Treatment was generally well tolerated; most common toxicities were hematologic. Twenty-four (25%) patients completed 27 weeks therapy without progression, including HGG: 1 (5%), ependymoma: 7 (37%), LGG: 7 (58%), medulloblastoma/PNET: 1, neuroblastoma: 1, and miscellaneous tumors: 7 (39%). Best response was complete response (one patient with medulloblastoma), partial response (12), stable disease (36), progressive disease (47), and inevaluable (1). Baseline serum thrombospondin levels were significantly higher in patients successfully completing therapy than in those who progressed (P = 0.009). CONCLUSION: The 5-drug regimen was well tolerated. Clinical activity was demonstrated in some but not all tumor strata.
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Inhibidores de la Angiogénesis/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Recurrencia Local de Neoplasia/tratamiento farmacológico , Neoplasias/tratamiento farmacológico , Neovascularización Patológica/tratamiento farmacológico , Adolescente , Adulto , Celecoxib , Niño , Preescolar , Ciclofosfamida/administración & dosificación , Etopósido/administración & dosificación , Femenino , Fenofibrato/administración & dosificación , Estudios de Seguimiento , Humanos , Lactante , Masculino , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Neoplasias/patología , Pronóstico , Estudios Prospectivos , Pirazoles/administración & dosificación , Sulfonamidas/administración & dosificación , Tasa de Supervivencia , Talidomida/administración & dosificación , Adulto JovenRESUMEN
Burkholderia pseudomallei is a category B pathogen and the causative agent of melioidosis--a serious infectious disease that is typically acquired directly from environmental reservoirs. Nearly all B. pseudomallei strains sequenced to date (> 85 isolates) contain gene clusters that are related to the contact-dependent growth inhibition (CDI) systems of γ-proteobacteria. CDI systems from Escherichia coli and Dickeya dadantii play significant roles in bacterial competition, suggesting these systems may also contribute to the competitive fitness of B. pseudomallei. Here, we identify 10 distinct CDI systems in B. pseudomallei based on polymorphisms within the cdiA-CT/cdiI coding regions, which are predicted to encode CdiA-CT/CdiI toxin/immunity protein pairs. Biochemical analysis of three B. pseudomallei CdiA-CTs revealed that each protein possesses a distinct tRNase activity capable of inhibiting cell growth. These toxin activities are blocked by cognate CdiI immunity proteins, which specifically bind the CdiA-CT and protect cells from growth inhibition. Using Burkholderia thailandensis E264 as a model, we show that a CDI system from B. pseudomallei 1026b mediates CDI and is capable of delivering CdiA-CT toxins derived from other B. pseudomallei strains. These results demonstrate that Burkholderia species contain functional CDI systems, which may confer a competitive advantage to these bacteria.
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Proteínas Bacterianas/inmunología , Toxinas Bacterianas/inmunología , Burkholderia pseudomallei/crecimiento & desarrollo , Burkholderia pseudomallei/metabolismo , Inhibición de Contacto , Melioidosis/inmunología , Melioidosis/microbiología , Proteínas Bacterianas/genética , Toxinas Bacterianas/genética , Burkholderia pseudomallei/enzimología , Burkholderia pseudomallei/genética , Endorribonucleasas/genética , Endorribonucleasas/metabolismo , Humanos , Familia de MultigenesRESUMEN
Venous gas emboli (VGE) can be readily detected in the bloodstream using existing ultrasound methods. No method currently exists to detect decompression-induced microbubbles in tissue. We hypothesized that dual-frequency ultrasound (DFU) could detect these microbubbles. With DFU, microbubbles are driven with two frequencies: a lower "pump" (set to the resonant frequency of the desired bubble size) and a higher "image" frequency. A bubble of the resonant size emits the sum and difference of the two transmitted frequencies. For this study we used a pump frequency of 2.25 MHz and an image frequency of 5.0 MHz, which detects bubbles of roughly 1-10 µm in diameter in a water tank. Four anesthetized swine were pressurized at 4.5 ATA for 2 h and decompressed over 5 min, inducing moderate to very severe VGE scores. Four sites on the thigh of each swine were monitored with DFU before and after the dives. A single mock dive was also performed. The number of sites returning signals consistent with microbubbles increased dramatically after the chamber dive (P < 0.01), but did not change with the mock dive. The increase in DFU signal after the chamber dive was sustained and present at multiple sites in multiple swine. This research shows for the first time that decompression-induced tissue microbubbles can be detected using DFU and that DFU could be used to monitor decompression-induced microbubbles at multiple sites on the body. Additionally, DFU could be used to track the time course of microbubble formation and growth during decompression stress.
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Enfermedad de Descompresión/diagnóstico por imagen , Embolia Aérea/diagnóstico por imagen , Microburbujas , Ultrasonido/métodos , Animales , Descompresión/métodos , Equipo Médico Durable , Femenino , Porcinos , Muslo/diagnóstico por imagen , UltrasonografíaRESUMEN
Exercise may produce micronuclei (presumably gas-filled bubbles) in tissue, which could serve as nucleation sites for bubbles during subsequent decompression stress. These micronuclei have never been directly detected in humans. Dual-frequency ultrasound (DFU) is a resonance-based, ultrasound technique capable of detecting and sizing small stationary bubbles. We surveyed for bubbles in the legs of six normal human subjects (ages 28-52 yr) after exercise using DFU. Eleven marked sites on the left thigh and calf were imaged using standard imaging ultrasound. Subjects then rested in a reclining chair for 2 h before exercise. For the hour before exercise, a series of baseline measurements was taken at each site using DFU. At least six baseline measurements were taken at each site. Subjects exercised at 80% of their age-adjusted maximal heart rate for 30 min on an upright bicycle ergometer. After exercise, the subjects returned to the chair, and multiple postexercise measurements were taken at the marked sites. Measurements continued until no further signals consistent with bubbles were returned or 1 h had elapsed. All subjects showed signals consistent with bubbles after exercise at at least one site. The percentage of sites in a given subject showing signals significantly greater than baseline (P < 0.01) at first measurement ranged from 9.1 to 100%. Overall, 58% of sites showed signals consistent with bubbles at the first postexercise measurement. Signals decreased over time after exercise. These data strongly suggest that exercise produces bubbles detectable using DFU.
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Ejercicio Físico/fisiología , Gases/sangre , Pierna/diagnóstico por imagen , Pierna/fisiología , Adulto , Enfermedad de Descompresión/diagnóstico por imagen , Enfermedad de Descompresión/fisiopatología , Humanos , Rodilla/diagnóstico por imagen , Rodilla/fisiología , Masculino , Persona de Mediana Edad , Procesamiento de Señales Asistido por Computador , Muslo/diagnóstico por imagen , Muslo/fisiología , Transductores , UltrasonografíaRESUMEN
Indirect evidence suggests that microbubbles that exist normally in tissue may play a key role in decompression sickness (DCS). Their sizes and locations are unknown. Dual-frequency ultrasound (DFU) exploits bubble resonance to detect bubbles over a wide size range and could potentially detect stationary tissue microbubbles. To test this capability, DFU was used to detect stationary microbubbles of known size (2-3 microm mean diameter) over a range of ultrasound pressures and microbubble concentrations. In gelatin phantoms doped with microbubbles and in ex vivo porcine tissue, signals indicative of bubbles were detected for microbubble concentrations of 5x10(5) per mL and greater. Signals were not returned from solid particle microspheres of similar size to the microbubbles or from saline controls. In the thigh of an anesthetized swine, signals were detected for concentrations of 5x10(7) per mL and greater. Because of its ability to detect bubbles over a wide range of sizes, this technique could potentially detect naturally-existing microbubbles in tissue and lead to (a) an improved understanding of the mechanics of bubble formation during decompression and (b) a new metric for evaluating DCS.
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Enfermedad de Descompresión/diagnóstico por imagen , Microburbujas , Animales , Gelatina , Fantasmas de Imagen , Sensibilidad y Especificidad , Porcinos , Muslo/diagnóstico por imagen , Ultrasonografía/métodosRESUMEN
Neisseria gonorrhoeae is a sexually transmitted pathogen that initiates infections in humans by adhering to the mucosal epithelium of the urogenital tract. The bacterium then enters the apical region of the cell and traffics across the cell to exit into the subepithelial matrix. Mutations in the fast intracellular trafficking (fitAB) locus cause the bacteria to transit a polarized epithelial monolayer more quickly than the wild-type parent and to replicate within cells at an accelerated rate. Here, we describe the crystal structure of the toxin-antitoxin heterodimer, FitAB, bound to a high affinity 36-bp DNA fragment from the fitAB promoter. FitA, the antitoxin, binds DNA through its ribbon-helix-helix motif and is tethered to FitB, the toxin, to form a heterodimer by the insertion of a four turn alpha-helix into an extensive FitB hydrophobic pocket. FitB is composed of a PIN (PilT N terminus) domain, with a central, twisted, 5-stranded parallel beta-sheet that is open on one side and flanked by five alpha-helices. FitB in the context of the FitAB complex does not display nuclease activity against tested PIN substrates. The FitAB complex points to the mechanism by which antitoxins with RHH motifs can block the activity of toxins with PIN domains. Interactions between two FitB molecules result in the formation of a tetramer of FitAB heterodimers, which binds to the 36-bp DNA fragment and provides an explanation for how FitB enhances the DNA binding affinity of FitA.
Asunto(s)
Proteínas Bacterianas/química , Proteínas Portadoras/química , ADN Bacteriano/metabolismo , Proteínas de Unión al ADN/química , Neisseria gonorrhoeae/química , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Antitoxinas/química , Antitoxinas/genética , Antitoxinas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/química , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Secuencia de Bases , Sitios de Unión/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Cristalografía por Rayos X , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Genes Bacterianos , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/patogenicidad , Regiones Promotoras Genéticas , Estructura Cuaternaria de Proteína , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homología de Secuencia de Aminoácido , Electricidad EstáticaRESUMEN
Purified pili and porin from Neisseria quickly mobilize calcium (Ca(2+)) stores in monocytes and epithelial cells, ultimately influencing host cell viability as well as bacterial intracellular survival. Here, we examined the Ca(2+) transients induced in human epithelial cells during infection by live, piliated N. gonorrhoeae. Porin induced an influx of Ca(2+) from the extracellular medium less than 60 s post infection. The porin-induced transient is followed by a pilus-induced release of Ca(2+) from intracellular stores. The timing of these events is similar to that observed using purified proteins. Interestingly, the porin-induced Ca(2+) flux is required for the pilus-induced transient, indicating that the pilus-induced Ca(2+) release is, itself, Ca(2+) dependent. Several lines of evidence indicate that porin is present on pili. Moreover, pilus retraction strongly influences the porin- and pilus-induced Ca(2+) fluxes. These and other results strongly suggest that the pilus and porin cooperate to modulate calcium signalling in epithelial cells, and propose a model to explain how N. gonorrhoeae triggers Ca(2+) transients in the initial stages of pilus-mediated attachment.
Asunto(s)
Calcio/metabolismo , Fimbrias Bacterianas/metabolismo , Neisseria gonorrhoeae/metabolismo , Porinas/metabolismo , Células Epiteliales/metabolismo , Células Epiteliales/microbiología , Humanos , Transducción de SeñalRESUMEN
The fit locus, encoding two proteins, FitA and FitB, was identified in a genetic screen for Neisseria gonorrhoeae determinants that affect trafficking across polarized epithelial cells. To better understand how the locus may control these activities, we have undertaken a biochemical analysis of FitA and FitB. FitA is a DNA-binding protein with a putative ribbon-helix-helix (RHH) motif. Purified FitA forms a homodimer that binds a 150 bp fit promoter sequence containing the translational start site. A putative beta strand mutant of FitA, FitA(R7A), is unable to bind this DNA, supporting further that FitA is a RHH protein. FitB interacts with FitA to form a 98 kDa complex. FitA/B binds DNA with a 38-fold higher affinity than the FitA homodimer. In DNase I footprint assays, FitA/B protects a 62-bp region within the fit promoter containing the predicted -10 sequence and an 8-bp inverted repeat, TGCTATCA-N(12)-TGATAGCA. FitA/B(His) is able to bind to either half-site alone with high affinity.
Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Proteínas Portadoras/química , Proteínas Portadoras/metabolismo , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Neisseria gonorrhoeae/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Secuencia de Consenso , Datos de Secuencia Molecular , Sondas de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Conformación Proteica , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Alineación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
TorsinA is a novel protein identified in the search for mutations underlying the human neurologic movement disorder, early onset torsion dystonia. Relatively little is understood about the normal function of torsinA or the physiological effects of the codon deletion associated with most cases of disease. Overexpression of wild-type torsinA in cultured cells by DNA transfection results in a reticular distribution of immunoreactive protein that co-localizes with endoplasmic reticulum resident chaperones, while the dystonia-related mutant form accumulates within concentric membrane whorls and nuclear-associated membrane stacks. In this study we examined the biogenesis of mutant torsinA-positive membrane inclusions using tetracycline-regulated herpes simplex virus amplicon vectors. At low expression levels, mutant torsinA was localized predominantly around the nucleus, while at high levels it was also concentrated within cytosolic spheroid inclusions. In contrast, the distribution of wild-type torsinA did not vary, appearing diffuse and reticular at all expression levels. These observations are consistent with descriptions of inducible membrane synthesis in other systems in which cytosolic membrane whorls are derived from multilayered membrane stacks that first form around the nuclear envelope. These results also suggest that formation of mutant torsinA-positive inclusions occurs at high expression levels in culture, whereas the perinuclear accumulation of the mutant protein is present even at low expression levels that are more likely to resemble those of the endogenous protein. These nuclear-associated membrane structures enriched in mutant torsinA may therefore be of greater relevance to understanding how the dystonia-related mutation compromises cellular physiology.