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1.
J Emerg Med ; 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38816260

ABSTRACT

BACKGROUND: Incidental findings are unrelated to a patient's complaint, found on diagnostic imaging, such as point-of-care ultrasound (POCUS). Incidental findings represent potential harms to patients and may lead to increased patient anxiety and health care costs related to downstream testing and surveillance. STUDY OBJECTIVES: In this study, we aimed to calculate the rate of incidental renal cysts found by POCUS. Further, we hoped to describe how emergency physicians relay the findings to patients. Lastly, we hoped to examine if patients suffered harms in the 12 months following identification of an incidental renal cyst. METHODS: From our single-center, academic emergency department (ED), we reviewed renal POCUS images from 1000 consecutive adult ED patients to determine if there was a renal cyst. Next, we performed manual chart review to determine if patients were informed of the incidental renal cyst or suffered any patient harms. RESULTS: We found the prevalence of renal cysts to be 6.5% (95% confidence interval: 4.9%-8.4%). Those with cysts were more likely to be older compared to those without (63 ± 14 vs. 49 ± 15 years of age). Only 8% of patients had evidence that they were informed of their incidental renal cyst. No patients received a biopsy or were diagnosed with renal cell carcinoma or polycystic kidney disease. CONCLUSION: Incidental renal cysts are common and are more likely to be found in older adults. In our study, physicians infrequently informed patients of their incidental finding.

3.
J Am Coll Emerg Physicians Open ; 3(4): e12794, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35978655

ABSTRACT

Objective: Point-of-care ultrasound for the detection of hydronephrosis is frequently used by emergency physicians. The aim of this study was to assess the accuracy of longitudinal views of the kidney compared with a combination of longitudinal and transverse views of the kidney on emergency physician-performed renal point-of-care ultrasound to detect hydronephrosis. Methods: This was a retrospective case-control study of patients who received a renal point-of-care ultrasound examination performed and interpreted as hydronephrosis in the emergency department (ED). These were then matched with a cohort of kidneys from different patients without hydronephrosis. Longitudinal ultrasound views and transverse ultrasound views were reviewed for the presence of hydronephrosis by ultrasound-trained emergency physicians. The gold standard of hydronephrosis was an overall interpretation based on the complete ultrasound examination consisting of both transverse and longitudinal views by ultrasound-trained emergency physicians. Results: Renal point-of-care ultrasound exams from 140 kidneys performed in the ED were enrolled in the study. The sensitivity and specificity of longitudinal ultrasound views compared with a combination of longitudinal and transverse ultrasound views of the kidney as a gold standard were 84.3% (95% confidence interval [CI], 77.2-89.9) and 92.9% (95% CI, 87.3-96.5), the positive predictive value was 92.2% (95% CI, 86.1-96.2), and the negative predictive value was 85.5% (95% CI, 78.9-90.7). The positive and negative likelihood ratios were 11.8 (95% CI, 6.5-21.5) and 0.2 (95% CI, 0.1-0.2), respectively. Conclusions: Longitudinal views of the kidney on ultrasound showed good sensitivity and specificity to detect the presence of hydronephrosis compared with a combination of longitudinal and transverse ultrasound views of the kidney. However, a combination of longitudinal and transverse ultrasound views may still be warranted in high-risk patients or in those with inadequate visualization of the upper pole of the kidney.

4.
Cureus ; 14(3): e23375, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35475095

ABSTRACT

Background Point-of-care ultrasound (POCUS) is an indispensable tool in emergency medicine. With the emergence of the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a need for improved diagnostic capabilities and prognostic indicators for patients who are symptomatic for COVID-19 has become apparent. POCUS has been demonstrated to be a useful diagnostic and prognostic tool in the emergency department (ED) in assessing other lung complications. Still, limited data regarding its utility in assessing COVID-19 are available. This study sought to evaluate whether POCUS findings in the ED were correlated with vital signs or laboratory abnormalities typically seen among patients with COVID-19. Methods A retrospective study was conducted that included 39 patients who presented with COVID-19 and systemic inflammatory response syndrome (SIRS) to a large, urban tertiary care ED. The study population was limited to adults aged 18 and above who came to the ED with the primary complaint of respiratory symptoms, met SIRS criteria on admission, and had images of at least one anterior and one posterior intercostal space per lung and a minimum of four intercostal spaces. POCUS images were obtained by trained operators in the ED using portable ultrasound machines, recorded in an image database, and reviewed by ultrasound fellowship-trained emergency physicians. Clinical data (e.g., acute phase reactants and vital signs) were obtained through a chart review of patients' electronic medical records. Results  Both the percentage of intercostal spaces with B-lines and the percentage of merging B-lines were correlated with decreased oxygen saturation on presentation. No other statistically significant correlations were observed between these sonographic findings and other vital signs or acute phase reactants, nor between these clinical data and the percentage of intercostal spaces that were positive for the shred sign. Conclusions With the emergence of the COVID-19 pandemic, emergency medicine physicians are on the frontline of identifying and caring for patients affected by the virus. This study found that sonographic findings associated with interstitial pneumonitis, notably merging B-lines, and the overall percentage of intercostal spaces with B-lines, were clearly associated with worsening oxygen saturation, now thought to be one of the driving causes of morbidity and mortality in COVID-19. As ultrasound has become a ubiquitous and indispensable tool in the ED, this study demonstrated its utility in assessing and managing patients with COVID-19. Bedside ultrasound is a cheap, fast, and non-invasive tool that healthcare providers can use as an essential adjunct in addition to laboratory markers and other imaging modalities for the diagnosis and prognosis of COVID-19.

5.
Cureus ; 14(1): e21620, 2022 Jan.
Article in English | MEDLINE | ID: mdl-35233305

ABSTRACT

We report the case of a transgender woman with HIV (CD4 349), shortness of breath, and chest pain, who was found to have multiple mycotic aortic aneurysms by point-of-care ultrasound (PoCUS). This report highlights the utility of point-of-care ultrasonography in the diagnosis and management of this rare clinical entity.Multiple mycotic aortic aneurysms and purulent pericarditis are uncommon. They have high morbidity and mortality and are associated with immunocompromised states (e.g., HIV). Diagnosis of the mycotic aneurysm, and its precursor, infectious aortitis, can be challenging, and delays in care can lead to poor outcomes. Often, as described in this case report, making the diagnosis requires a high clinical suspicion, multiple imaging modalities, and laboratory studies.

6.
West J Emerg Med ; 22(6): 1335-1340, 2021 Nov 05.
Article in English | MEDLINE | ID: mdl-34787559

ABSTRACT

INTRODUCTION: To determine the accuracy of landmark-guided shoulder joint injections (LGI) with point-of-care ultrasound for patients with anterior shoulder dislocations. METHODS: Patients with anterior shoulder dislocations who underwent LGI were enrolled at our tertiary-care and trauma center. LGI attempts were recorded by an ultrasound fellowship-trained ED physician who determined if they were placed successfully. Pain and satisfaction scores were recorded. RESULTS: A total of 34 patients with anterior shoulder dislocation and their treating ED physicians were enrolled. 41.1% of all LGI were determined to be misplaced (n=14). Patients with successful LGI had a greater decrease in mean pain scores post-LGI. CONCLUSIONS: LGI had a substantial failure rate in our study. Using ultrasound-guidance to assist intra-articular injections may increase its accuracy and thus reduce pain and the need for subsequent procedural sedation.


Subject(s)
Shoulder Dislocation , Shoulder Joint , Humans , Injections, Intra-Articular , Shoulder Dislocation/diagnostic imaging , Shoulder Dislocation/drug therapy , Shoulder Joint/diagnostic imaging , Ultrasonography , Ultrasonography, Interventional
9.
Crit Care ; 19: 282, 2015 Jul 21.
Article in English | MEDLINE | ID: mdl-26325623

ABSTRACT

INTRODUCTION: In low-resource settings it is not always possible to acquire the information required to diagnose acute respiratory distress syndrome (ARDS). Ultrasound and pulse oximetry, however, may be available in these settings. This study was designed to test whether pulmonary ultrasound and pulse oximetry could be used in place of traditional radiographic and oxygenation evaluation for ARDS. METHODS: This study was a prospective, single-center study in the ICU of Harborview Medical Center, a referral hospital in Seattle, Washington, USA. Bedside pulmonary ultrasound was performed on ICU patients receiving invasive mechanical ventilation. Pulse oximetric oxygen saturation (SpO2), partial pressure of oxygen (PaO2), fraction of inspired oxygen (FiO2), provider diagnoses, and chest radiograph closest to time of ultrasound were recorded or interpreted. RESULTS: One hundred and twenty three ultrasound assessments were performed on 77 consecutively enrolled patients with respiratory failure. Oxygenation and radiographic criteria for ARDS were met in 35 assessments. Where SpO2 ≤ 97%, the Spearman rank correlation coefficient between SpO2/FiO2 and PaO2/FiO2 was 0.83, p < 0.0001. The sensitivity and specificity of the previously reported threshold of SpO2/FiO2 ≤ 315 for PaO2/FiO2 ≤ 300 was 83% (95% confidence interval (CI) 68-93), and 50% (95% CI 1-99), respectively. Sensitivity and specificity of SpO2/FiO2 ≤ 235 for PaO2/FiO2 ≤ 200 was 70% (95% CI 47-87), and 90% (95% CI 68-99), respectively. For pulmonary ultrasound assessments interpreted by the study physician, the sensitivity and specificity of ultrasound interstitial syndrome bilaterally and involving at least three lung fields were 80% (95% CI 63-92) and 62% (95% CI 49-74) for radiographic criteria for ARDS. Combining SpO2/FiO2 with ultrasound to determine oxygenation and radiographic criteria for ARDS, the sensitivity was 83% (95% CI 52-98) and specificity was 62% (95% CI 38-82). For moderate-severe ARDS criteria (PaO2/FiO2 ≤ 200), sensitivity was 64% (95% CI 31-89) and specificity was 86% (95% CI 65-97). Excluding repeat assessments and independent interpretation of ultrasound images did not significantly alter the sensitivity measures. CONCLUSIONS: Pulse oximetry and pulmonary ultrasound may be useful tools to screen for, or rule out, impaired oxygenation or lung abnormalities consistent with ARDS in under-resourced settings where arterial blood gas testing and chest radiography are not readily available.


Subject(s)
Blood Gas Analysis , Lung/diagnostic imaging , Oximetry , Respiratory Distress Syndrome/diagnosis , Adult , Aged , Female , Humans , Male , Middle Aged , Observer Variation , Pilot Projects , Prospective Studies , Radiography, Thoracic , Reproducibility of Results , Respiratory Distress Syndrome/blood , Respiratory Distress Syndrome/diagnostic imaging , Sensitivity and Specificity , Ultrasonography
10.
Crit Ultrasound J ; 7(1): 28, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26123609

ABSTRACT

BACKGROUND: Access to ultrasound has increased significantly in resource-limited settings, including the developing world; however, there remains a lack of sonography education and ultrasound-trained physician support in developing countries. To further investigate this potential knowledge gap, our primary objective was to assess perceived barriers to ultrasound use in resource-limited settings by surveying care providers who practice in low- and middle-income settings. METHODS: A 25-question online survey was made available to health care providers who work with an ultrasound machine in low- and middle-income countries (LMICs), including doctors, nurses, technicians, and clinical officers. This was a convenience sample obtained from list-serves of ultrasound and radiologic societies. The survey was analyzed, and descriptive results were obtained. RESULTS: One hundred and thirty-eight respondents representing 44 LMICs including countries from the continents of Africa, South America, and Asia completed the survey, with a response rate of 9.6 %. Ninety-one percent of the respondents were doctors, and 9 % were nurses or other providers. Applications for ultrasound were diverse, including obstetrics (75 %), DVT evaluation (51 %), abscess evaluation (54 %), cardiac evaluation (64 %), inferior vena cava (IVC) assessment (49 %), Focused Assessment Sonography for Trauma (FAST) exam (64 %), biliary tree assessment (54 %), and other applications. The respondents identified the following barriers to use of ultrasound: lack of training (60 %), lack of equipment (45 %), ultrasound machine malfunction (37 %), and lack of ultrasound maintenance capability (47 %). Seventy-four percent of the respondents wished to have further training in ultrasound, and 82 % were open to receiving distance learning or telesonography training. Subjects used communication tools including Skype, Dropbox, emailed photos, and picture archiving and communication system (PACS) as ways to communicate and receive feedback on ultrasound images. CONCLUSIONS: Health care providers in the developing world identify lack of training as a primary barrier to regular use of ultrasound in their practice. While equipment requirements including maintenance and cost of machines are also important factors, future research is warranted on best practices for training methods, including telesonography and distance learning to enhance ultrasound use in low-resource settings.

11.
J Surg Educ ; 72(4): e82-7, 2015.
Article in English | MEDLINE | ID: mdl-25911457

ABSTRACT

OBJECTIVE: Point-of-care ultrasound (POCUS) is a vital tool for diagnosis and management of critically ill patients, particularly in resource-limited settings where access to diagnostic imaging may be constrained. We aimed to develop a novel POCUS training curriculum for surgical practice in the United States and in resource-limited settings in low- and middle-income countries and to determine its effect on surgical resident self-assessments of efficacy and confidence. DESIGN: We conducted an observational cohort study evaluating a POCUS training course that comprised 7 sessions of 2 hours each with didactics and proctored skills stations covering ultrasound applications for trauma (Focused Assessement with Sonography for Trauma (FAST) examination), obstetrics, vascular, soft tissue, regional anesthesia, focused echocardiography, and ultrasound guidance for procedures. Surveys on attitudes, prior experience, and confidence in point-of-care ultrasound applications were conducted before and after the course. SETTING: General Surgery Training Program in Seattle, Washington. PARTICIPANTS: A total of 16 residents participated in the course; 15 and 10 residents completed the precourse and postcourse surveys, respectively. RESULTS: The mean composite confidence score from pretest compared with posttest improved from 23.3 (±10.2) to 37.8 (±6.7). Median confidence scores (1-6 scale) improved from 1.5 to 5.0 in performance of FAST (p < 0.001). Residents reported greater confidence in their ability to identify pericardial (2 to 4, p = 0.009) and peritoneal fluid (2 to 4.5, p < 0.001), to use ultrasound to guide procedures (3.5 to 4.0, p = 0.008), and to estimate ejection fraction (1 to 4, p = 0.004). Both before and after training, surgical residents overwhelmingly agreed with statements that ultrasound would improve their US-based practice, make them a better surgical resident, and improve their practice in resource-limited settings. CONCLUSIONS: After a POCUS course designed specifically for surgeons, surgical residents had improved self-efficacy and confidence levels across a broad range of skills.


Subject(s)
General Surgery/education , Internship and Residency , Point-of-Care Systems , Ultrasonography , Global Health/education , Treatment Outcome
12.
West J Emerg Med ; 15(6): 636-40, 2014 Sep.
Article in English | MEDLINE | ID: mdl-25247032

ABSTRACT

INTRODUCTION: Late obstetric emergencies are time critical presentations in the emergency department. Evaluation to ensure the safety of mother and child includes rapid assessment of fetal viability, fetal heart rate (FHR), fetal lie, and estimated gestational age (EGA). Point-of-care (POC) obstetric ultrasound (OBUS) offers the advantage of being able to provide all these measurements. We studied the impact of POC OBUS training on emergency physician (EP) confidence, knowledge, and OBUS skill performance on a live model. METHODS: This is a prospective observational study evaluating an educational intervention we designed, called the BE-SAFE curriculum (BEdside Sonography for the Assessment of the Fetus in Emergencies). Subjects were a convenience sample of EP attendings (N=17) and residents (N=14). Prior to the educational intervention, participants completed a self-assessment survey on their confidence regarding OBUS, and took a pre-test to assess their baseline knowledge of OBUS. They then completed a 3-hour training session consisting of didactic and hands-on education in OBUS. After training, each subject's time and accuracy of performance of FHR, EGA, and fetal lie was recorded. Post-intervention knowledge tests and confidence surveys were administered. Results were compared with non-parametric t-tests. RESULTS: Pre- and post-test knowledge assessment scores for previously untrained EPs improved from 65.7% [SD=20.8] to 90% [SD=8.2] (p<0.0007). Self-confidence on a scale of 1-6 improved significantly for identification of FHR, fetal lie, and EGA. After training, the average times for completion of OBUS critical skills were as follows: cardiac activity (9s), FHR (68.6s), fetal lie (28.1s), and EGA (158.1 sec). EGA estimates averaged 28w0d (25w0d-30w6d) for the model's true gestational age of 27w0d. CONCLUSION: After a focused POC OBUS training intervention, the BE-SAFE educational intervention, EPs can accurately and rapidly use ultrasound to determine FHR, fetal lie, and estimate gestational age in mid-late pregnancy.


Subject(s)
Emergency Service, Hospital , Fetal Diseases/diagnostic imaging , Obstetrics/education , Pregnancy Complications/diagnostic imaging , Clinical Competence , Educational Measurement , Female , Gestational Age , Humans , Obstetrics/instrumentation , Point-of-Care Systems , Pregnancy , Pregnancy Trimester, Third , Prospective Studies , Ultrasonography
13.
J Emerg Med ; 47(1): e1-3, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24199726

ABSTRACT

BACKGROUND: Presentation of congenital megaureter in adult life is rare; patients usually become symptomatic in childhood. CASE REPORT: A 32-year-old man presented to the Emergency Department (ED) with dyspnea, tongue swelling, and a rash, which he attributed to amoxicillin he had taken shortly prior to onset of symptoms. He was hypotensive on arrival to the ED. To further evaluate the hypotension, point-of-care ultrasound of the heart, lungs, and abdomen were performed while treatment for anaphylaxis was initiated. Ultrasound examination did not identify a cause for hypotension, but the treating physician noted an anechoic structural abnormality posterior to the bladder, suggestive of megaureter. The patient responded well to treatment of anaphylaxis; further history and diagnostic imaging subsequently confirmed a diagnosis of congenital megaureter. CONCLUSION: We report an unusual case of congenital megaureter, identified by point-of-care ultrasound performed to evaluate hypotension. Clinicians performing limited ultrasound examinations must be attentive to incidental findings that will require follow-up.


Subject(s)
Point-of-Care Systems , Ureter/abnormalities , Ureter/diagnostic imaging , Adult , Anaphylaxis/chemically induced , Anaphylaxis/therapy , Humans , Hypotension/etiology , Incidental Findings , Male , Radiography , Ultrasonography
14.
J Emerg Med ; 46(1): 46-53, 2014 Jan.
Article in English | MEDLINE | ID: mdl-23942153

ABSTRACT

BACKGROUND: Bedside ultrasound (US) is associated with improved patient satisfaction, perhaps as a consequence of improved time to diagnosis and decreased length of stay (LOS). OBJECTIVES: Our study aimed to quantify the association between beside US and patient satisfaction and to assess patient attitudes toward US and perception of their interaction with the clinician performing the examination. METHODS: We enrolled a convenience sample of adult patients who received a bedside US. The control group had similar LOS and presenting complaints but did not have a bedside US. Both groups answered survey questions during their emergency department (ED) visit and again by telephone 1 week later. The questionnaire assessed patient perceptions and satisfaction on a 5-point Likert scale. RESULTS: Seventy patients were enrolled over 10 months. The intervention group had significantly higher scores on overall ED satisfaction (4.69 vs. 4.23; mean difference 0.46; 95% confidence interval [CI] 0.17-0.75), diagnostic testing (4.54 vs. 4.09; mean difference 0.46; 95% CI 0.16-0.76), and skills/abilities of the emergency physician (4.77 vs. 4.14; mean difference 0.63; 95% CI 0.29-0.96). A trend to higher scores for the intervention group persisted on follow-up survey. CONCLUSIONS: Patients who had a bedside US had statistically significant higher satisfaction scores with overall ED care, diagnostic testing, and with their perception of the emergency physician. Bedside US has the potential not only to expedite care and diagnosis, but also to maximize satisfaction scores and improve the patient-physician relationship, which has increasing relevance to health care organizations and hospitals that rely on satisfaction surveys.


Subject(s)
Patient Satisfaction , Physician-Patient Relations , Point-of-Care Systems , Ultrasonography , Adult , Aged , Clinical Competence , Emergency Service, Hospital , Female , Humans , Length of Stay , Male , Middle Aged , Perception , Prospective Studies , Surveys and Questionnaires
16.
Emerg Med Pract ; 13(3): 1-27; quiz 27-8, 2011 Mar.
Article in English | MEDLINE | ID: mdl-22164403

ABSTRACT

Paramedics bring into the ED an elderly man who is complaining of right-sided chest and abdominal pain. Earlier this morning, a friend had arrived at the patient's home and found him on the floor at the bottom of the stairs. The patient is in pain, somewhat altered, and unable to provide further details about what happened. After numerous attempts, the paramedics were only able to place a 22-gauge peripheral line. On examination, his blood pressure is 98/55 mm Hg, heart rate is 118 beats per minute, respiratory rate is 32 breaths per minute, oxygen saturation is 94% on a nonrebreather, and temperature is 36.0 degrees C (96.8 degrees F). His Glasgow Coma Scale score is 12 (eyes 3, verbal 4, motor 5). Given the unclear events surrounding his presentation and the concern for trauma, the patient is boarded and collared. His chest is stable but tender, and because of noise in the resuscitation room, you have difficulty auscultating breath sounds. The abdominal examination is notable for marked tenderness over the right upper quadrant and right flank, with some guarding. There is also mild asymmetric swelling of his right lower extremity. The patient is critically ill, his history is limited, and at this point the differential is quite broad. You consider the possibility of a syncopal episode followed by a fall, with a closed head injury, blunt thoracic trauma, and blunt abdominal trauma. His hypotension could be secondary to hypovolemia (dehydration or blood loss due to a ruptured aortic aneurysm), heart failure (left- or right-sided dysfunction), cardiac tamponade, tension pneumothorax, or sepsis. Your ED recently purchased an ultrasound machine, you wonder whether bedside ultrasound can help narrow the differential and guide your resuscitation. You call over one of your new faculty members who just finished resident training; a fortunate decision for both you and the patient.


Subject(s)
Emergency Medicine , Point-of-Care Systems , Ultrasonography/methods , Aged , Evidence-Based Medicine , Hemopneumothorax/diagnostic imaging , Humans , Male , Risk Management , Wounds and Injuries/diagnostic imaging
17.
Virtual Mentor ; 12(9): 744-9, 2010 Sep 01.
Article in English | MEDLINE | ID: mdl-23186883
18.
Injury ; 40(1): 40-3, 2009 Jan.
Article in English | MEDLINE | ID: mdl-19117561

ABSTRACT

BACKGROUND: Stab wounds to the thorax and upper abdomen have the potential to cause pneumothorax (PTX). When a CXR (CXR) obtained during initial resuscitation is negative, a second CXR (CXR-2) is commonly performed with the goal of identifying delayed PTX. OBJECTIVES: To assess the diagnostic yield of the CXR-2 in identifying delayed PTX. METHODS: Prospective observational study of patients (age >or=13 years) with stab wounds to the thorax (chest/back) and upper abdomen with suspected PTX, in a level 1 trauma centre. Patients were included if they had a negative initial CXR followed by a repeat CXR 3-6h after the initial one. EXCLUSION CRITERIA: patients who died, were transferred out of the ED, or received chest tubes before the second CXR. The outcome of interest was delayed PTX. All CXR were read by an attending radiologist. To test the inter-observer agreement, another blinded radiologist reviewed 20% of CXR. Continuous data is presented as mean+/-standard deviation and categorical data as percentages with 95% confidence interval (CI). Kappa statistics were used to measure the inter-observer agreement between radiologists. RESULTS: Between January 2003 and December 2006 a total of 185 patients qualified for the enrollment (mean age: 28+/-10 years, age range: 13-65, 94% male). Only 2 patients (1.1%, 95% CI, 0.4- 4.1%) had PTX on the CXR-2. Both patients received chest tubes. The inter-observer agreement for radiology reports was high (kappa: 0.79). CONCLUSION: Occurrence of delayed PTX in patients with stab wounds to the thorax and upper abdomen and negative triage CXR is rare.


Subject(s)
Abdominal Injuries/complications , Pneumothorax/etiology , Thoracic Injuries/complications , Wounds, Stab/complications , Abdominal Injuries/diagnostic imaging , Adolescent , Adult , Female , Humans , Lung/diagnostic imaging , Male , Pneumothorax/diagnostic imaging , Pneumothorax/epidemiology , Probability , Prospective Studies , Radiography , Thoracic Injuries/diagnostic imaging , Time Factors , Triage/methods , Wounds, Stab/diagnostic imaging , Young Adult
19.
Mol Biochem Parasitol ; 143(1): 80-9, 2005 Sep.
Article in English | MEDLINE | ID: mdl-15996766

ABSTRACT

Peroxiredoxins are an important class of antioxidant enzymes found from Archaea to humans, which reduce and thereby detoxify peroxides and peroxynitrites. The major thiol-containing surface antigen of the invasive ameba, Entamoeba histolytica, is a peroxiredoxin and is likely to be important during the transition from the anaerobic environment of the large intestine to human tissues. The closely related species, Entamoeba dispar, is incapable of invasion and more sensitive to hydrogen peroxide, yet also has a peroxiredoxin. We cloned and expressed the two active recombinant enzymes and found that their activity was similar by a fluorometric stopped-flow assay, giving a Km of <10 microM for hydrogen peroxide. Three monoclonal antibodies produced to recombinant E. histolytica peroxiredoxin cross-reacted with Entamoeba dispar.E. histolytica contains as much as 50 times more peroxiredoxin than E. dispar as demonstrated by a sensitive capture ELISA. In addition, the peroxiredoxin is present largely on the outer surface of the cell, in contrast to E. dispar. This unusual peroxiredoxin localizes to the site of parasite-host cell contact where it can effectively counteract oxidants generated by host cells, thus facilitating invasion.


Subject(s)
Oxidants/toxicity , Peroxidases/metabolism , Protozoan Proteins/metabolism , Amino Acid Sequence , Animals , Base Sequence , Conserved Sequence , Entamoeba histolytica , Host-Parasite Interactions , Molecular Sequence Data , Peroxidases/chemistry , Peroxidases/genetics , Peroxiredoxins , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid
20.
J Neurosci ; 23(28): 9276-88, 2003 Oct 15.
Article in English | MEDLINE | ID: mdl-14561854

ABSTRACT

Increased expression of certain extracellular matrix (ECM) molecules after CNS injury is believed to restrict axonal regeneration. The chondroitin sulfate proteoglycans (CSPGs) are one such class of ECM molecules that inhibit neurite outgrowth in vitro and are upregulated after CNS injury. We examined growth responses of several classes of axons to this inhibitory environment in the presence of a cellular fibroblast bridge in a spinal cord lesion site and after a growth factor stimulus at the lesion site (fibroblasts genetically modified to secrete NGF). Immunohistochemical analysis showed dense labeling of the CSPGs NG2, brevican, neurocan, versican, and phosphacan at the host-lesion interface after spinal cord injury (SCI). Furthermore, robust expression of NG2, and to a lesser extent versican, was also observed throughout grafts of control and NGF-secreting fibroblasts. Despite this inhibitory milieu, several axonal classes penetrated control fibroblast grafts, including dorsal column sensory, rubrospinal, and nociceptive axons. Axon growth was amplified more in the presence of NGF-secreting grafts. Confocal microscopy demonstrated that axon growth was, paradoxically, preferentially associated with NG2-rich substrates in both graft types. NG2 expression also increased after sciatic nerve injury, wherein axons successfully regenerate. Cellular sources of NG2 in SCI and peripheral nerve lesion sites included Schwann cells and endothelial cells. Notably, these same cellular sources in lesion sites produced the cell adhesion molecules L1 and laminin, and these molecules all colocalized. Thus, axons grow along substrates coexpressing both inhibitory and permissive molecules, suggesting that regeneration is successful when local permissive signals balance and exceed inhibitory signals.


Subject(s)
Axons/physiology , Chondroitin Sulfate Proteoglycans/metabolism , Nerve Regeneration/physiology , Spinal Cord Injuries/physiopathology , Animals , Antigens/biosynthesis , Axons/drug effects , Cell Adhesion Molecules/biosynthesis , Cell Division/physiology , Cells, Cultured , Chondroitin Sulfate Proteoglycans/biosynthesis , Disease Models, Animal , Endothelium, Vascular/cytology , Endothelium, Vascular/metabolism , Extracellular Matrix/metabolism , Female , Fibroblasts/cytology , Fibroblasts/metabolism , Fibroblasts/transplantation , Graft Survival , Laminin/metabolism , Lectins, C-Type , Nerve Growth Factor/biosynthesis , Nerve Growth Factor/genetics , Nerve Growth Factor/pharmacology , Proteoglycans/biosynthesis , Rats , Rats, Inbred F344 , Schwann Cells/cytology , Schwann Cells/metabolism , Sciatic Neuropathy/pathology , Sciatic Neuropathy/physiopathology , Spinal Cord/metabolism , Spinal Cord/pathology , Spinal Cord Injuries/pathology , Versicans
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