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1.
bioRxiv ; 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-37503170

RESUMO

Weather-related disasters can radically alter ecosystems. When disaster-driven ecological damage persists, the selective pressures exerted on individuals can change, eventually leading to phenotypic adjustments. For group-living animals, social relationships are believed to help individuals cope with environmental challenges and may be a critical mechanism enabling adaptation to ecosystems degraded by disasters. Yet, whether natural disasters alter selective pressures on patterns of social interactions and whether group-living animals can, as a result, adaptively change their social relationships remains untested. Here, we leveraged unique data collected on rhesus macaques from 5 years before to 5 years after a category 4 hurricane, leading to persistent deforestation which exacerbated monkeys' exposure to intense heat. In response, macaques increased tolerance for and decreased aggression toward other monkeys, facilitating access to scarce shade critical for thermoregulation. Social tolerance predicted individual survival for 5 years after the hurricane, but not before it, revealing a clear shift in the adaptive function of social relationships in this population. We demonstrate that an extreme climatic event altered selection on sociality and triggered substantial and persistent changes in the social structure of a primate species. Our findings unveil the function and adaptive flexibility of social relationships in degraded ecosystems and identify natural disasters as potential evolutionary drivers of sociality. One-Sentence Summary: Testard et al. show that a natural disaster altered selection on sociality in group-living primates triggering persistent changes in their social structure.

2.
Appl Radiat Isot ; 190: 110509, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36306679

RESUMO

To determine the safety of using argon as a deuteron beam stopping material, the  40Ar(d,p)41Ar cross section was measured at average deuteron energies of 3.6 MeV, 5.5 MeV, and 7.0 MeV using an activation method. A 16-MeV deuteron beam produced by Lawrence Berkeley National Laboratory's 88-Inch Cyclotron was degraded to each energy by nickel foils and the front wall of an aluminum gas chamber. The reduced-energy deuterons were used to activate a sample of natAr gas. After each irradiation, the gas chamber's  41Ar activation was measured with a high-purity germanium detector. The cross sections measured were larger than a previous measurement by ∼40%.


Assuntos
Ciclotrons
3.
Lymphology ; 51(1): 18-27, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30248728

RESUMO

Gorham-Stout disease - also known as "disappearing bone disease" is currently considered a single entity with varying clinical manifestations. We reviewed the existent literature from the earliest historic description(Jackson in 1838) and Gorham and Stout's original series of patients, multiple case reports and series since. After analyzing 212 reported cases, we identified 76 cases with details that recorded either a history of multifocal disease or an identifiable history of preceding trauma. From this review, we have defined two distinct Gorham-Stout entities - those characteristically associated with lymphangiomatosis [a form of GLA (generalized lymphangiomatosis) questionably distinguishable by bone biopsy and radiologic appearance] with multifocal distributed bone lesions, and those others, usually self-limited, first appearing after a traumatic event and always confined to a single bone or closely adjacent one. Multifocal disease is more likely to have chylothorax as a complication. These two Gorham-Stout entities differ in their demographic distribution, clinical history and manifestations, and they follow divergent clinical courses. The prognosis differs, and so should approaches to monitoring as well as acute and long-term treatment. Further research should seek to identify and define the differences in pathology and molecular mechanisms.


Assuntos
Quilotórax/patologia , Contusões/patologia , Fraturas Ósseas/patologia , Linfangioma/patologia , Osteólise Essencial/patologia , Adolescente , Adulto , Idoso , Osso e Ossos/patologia , Criança , Pré-Escolar , Quilotórax/diagnóstico , Quilotórax/etiologia , Quilotórax/cirurgia , Contusões/complicações , Contusões/diagnóstico , Gerenciamento Clínico , Feminino , Fraturas Ósseas/complicações , Fraturas Ósseas/diagnóstico , Humanos , Lactente , Linfangioma/complicações , Linfangioma/diagnóstico , Masculino , Pessoa de Meia-Idade , Osteólise Essencial/diagnóstico , Osteólise Essencial/etiologia , Osteólise Essencial/cirurgia , Prognóstico , Resultado do Tratamento
4.
Clin Otolaryngol ; 41(6): 660-665, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26519088

RESUMO

OBJECTIVE: The objective was to ascertain the efficacy of a new analgesic regimen introduced in children undergoing (adeno)tonsillectomy in view of the ban on codeine use in children <12 years by the European Medicines Agency (EMA) and UK Medicines and Healthcare Products Regulatory Agency (MHRA). DESIGN: Prospective pilot study at a paediatric tertiary referral centre. MATERIALS AND METHODS: A total of 176 children undergoing (adeno) tonsillectomy over a 5-month period (Sept 2013-Jan 2014) were included in the study. Data were prospectively collected on analgesia used peri-operatively and patients were discharged on regular paracetamol and ibuprofen for 7 days and three doses of oral morphine sulphate solution to be used on days 3, 4 and 5. Pain scores were recorded on days 1-10 post-operatively using the Wong Baker Faces Pain Rating scale. RESULTS: The pain scores were significantly better (P-value < 0.0001) in children who were compliant with morphine (n = 93) than those who were not (n = 32). We also found that children who were compliant with morphine were less likely to seek help out of hours (P-value < 0.001). CONCLUSIONS: Oral morphine sulphate solution provides a reasonable alternative to codeine, albeit one should bear in mind that parental concerns and adverse effects of the drug were seen in a minority of patients (n = 11) and anaesthetists were reluctant to prescribe the drug in cases of severe OSA or associated central apnoeas (n = 7).


Assuntos
Adenoidectomia/efeitos adversos , Analgésicos/uso terapêutico , Dor Pós-Operatória/tratamento farmacológico , Tonsilectomia/efeitos adversos , Acetaminofen/uso terapêutico , Criança , Pré-Escolar , Quimioterapia Combinada , Feminino , Humanos , Ibuprofeno/uso terapêutico , Masculino , Morfina/uso terapêutico , Manejo da Dor , Dor Pós-Operatória/diagnóstico , Dor Pós-Operatória/etiologia , Projetos Piloto , Estudos Prospectivos , Escócia
9.
J Laryngol Otol ; 121(6): 559-62, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17156577

RESUMO

OBJECTIVES: The aims of this study were: (1) to establish current UK practice with respect to 'group and save' of serum for paediatric tonsillectomy; and (2) to determine the need to group and save serum prior to routine paediatric tonsillectomy. METHODS: Members of the British Association of Otorhinolaryngologists-Head and Neck Surgeons were surveyed by e-mail. A prospective study (November 1999 to August 2002) of all children undergoing tonsillectomy or adenotonsillectomy was undertaken. Outcome measures included reactionary and secondary post-tonsillectomy haemorrhage rates, blood transfusion requirements and 'return to theatre' rates. RESULTS: We surveyed 464 association members. The response rate was 52 per cent (n=242). Twenty-five respondents (10.3 per cent) indicated that they undertook group and save prior to tonsillectomy or adenotonsillectomy in children. Two hundred and seventeen (89.7 per cent) indicated that they did not. Of those who did group and save for children, 20 respondents (80 per cent) did so routinely. The remaining five respondents (20 per cent) did so only for children weighing less than 15 kg (n=4) or less than 10 kg (n=1). During the study period, 325 children underwent tonsillectomy or adenotonsillectomy. The reactionary haemorrhage rate was 0.6 per cent (n=2) and the secondary haemorrhage rate 5.5 per cent (n=18). The two cases of reactionary haemorrhage were returned to theatre immediately for control of haemostasis. All secondary haemorrhages were managed conservatively. No child required blood transfusion during the study period. CONCLUSION: Routine group and save of serum for children undergoing elective tonsillectomy or adenotonsillectomy seems unnecessary. We recommend that it be undertaken only in special circumstances.


Assuntos
Adenoidectomia/efeitos adversos , Tipagem e Reações Cruzadas Sanguíneas , Hemorragia Pós-Operatória/etiologia , Tonsilectomia/efeitos adversos , Adolescente , Criança , Pré-Escolar , Pesquisas sobre Atenção à Saúde , Hemostasia Cirúrgica/métodos , Humanos , Hemorragia Pós-Operatória/terapia , Estudos Prospectivos , Sociedades Médicas , Resultado do Tratamento , Reino Unido
10.
J Laryngol Otol ; 120(4): 314-8, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16623976

RESUMO

OBJECTIVE: This survey assesses patients' perceptions of a daily otolaryngology ward round in a teaching hospital. METHODS: Initial, open-ended questionnaires generated themes from which a structured questionnaire was constructed. Patients' perceptions in a wide range of areas were examined by asking them to indicate on a Likert scale the extent to which they agreed or disagreed with a number of statements concerning various aspects of the ward round. RESULTS: One hundred patients were surveyed. The response rate was 79 per cent. The findings showed overall patient satisfaction with the ward round, particularly in the areas of information-giving regarding diagnosis, treatment and follow-up arrangements. The large size of the ward round appeared to be intimidating and induced anxiety for approximately one-third of patients. Patients wished the roles of staff present to be better defined and to be informed of the presence of medical students. One-third of patients perceived staff to use language that was difficult to understand. CONCLUSIONS: The survey identified some improvement opportunities and will assist our department with its on-going endeavours to improve the ward round experience for both patients and staff.


Assuntos
Otolaringologia , Satisfação do Paciente , Hospitais Gerais , Hospitais de Ensino , Humanos , Planejamento de Assistência ao Paciente , Equipe de Assistência ao Paciente , Relações Médico-Paciente , Inquéritos e Questionários
11.
J Laryngol Otol ; 120(6): 450-4, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16441968

RESUMO

OBJECTIVE: To determine whether bipolar dissection tonsillectomy is associated with a higher post-operative haemorrhage rate than cold dissection tonsillectomy. DESIGN: Prospective, randomized, controlled trial. SETTING: Otolaryngology department of a teaching hospital. PARTICIPANTS: Two hundred and forty-five patients undergoing elective tonsillectomy between July 2002 and November 2004. INTERVENTIONS: Patients were randomly assigned to either bipolar dissection or cold dissection (with bipolar haemostasis). MAIN OUTCOME MEASURES: Post-operative haemorrhage rates, management (conservative or surgical) and blood transfusion requirements were recorded. The grade of surgeon and history of quinsy were also recorded. RESULTS: One hundred and forty-one patients (58 per cent) were randomized to the bipolar dissection and 104 (42 per cent) to the cold dissection groups. Seventeen patients (12.1 per cent) in the bipolar dissection group and eight patients (7.7 per cent) in the cold dissection group suffered haemorrhage (p = 1.0; degrees of freedom (Df) 0.0; 95 per cent confidence intervals (CI) -0.1 to 0.0). The haemorrhage rates for procedures conducted by senior house officers, specialist registrars and consultants were 11.4 per cent, 10.3 per cent and 5.0 per cent, respectively. Two patients required surgical intervention, both from the bipolar dissection group. No patients required blood transfusion. A history of quinsy was not associated with an increased haemorrhage rate. CONCLUSION: The difference in haemorrhage rates between groups and surgeon grades did not reach statistical significance. Nonetheless the trend towards a greater incidence of haemorrhage in the bipolar group and in procedures conducted by more junior surgeons during the trial raised concerns. The results of the National Prospective Tonsillectomy Audit and our interim results have led us to abandon the trial and disallow the use of bipolar dissection in tonsillectomies performed by junior staff members.


Assuntos
Diatermia/efeitos adversos , Dissecação/efeitos adversos , Hemorragia Pós-Operatória/etiologia , Tonsilectomia/métodos , Adulto , Criança , Competência Clínica , Diatermia/métodos , Dissecação/métodos , Hemostasia Cirúrgica , Humanos , Otolaringologia , Estudos Prospectivos , Tonsilectomia/efeitos adversos , Tonsilite/cirurgia
12.
J Laryngol Otol ; 119(11): 894-8, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16354342

RESUMO

The aim of this study was to determine whether certain weather variables influence the secondary post-tonsillectomy haemorrhage rate and to examine the influence of a change in these variables on secondary haemorrhage. This was a prospective study carried out in a tertiary referral institution. All patients undergoing bilateral tonsillectomy over a one-year period were included. Local weather data, including daily temperature (max/min), relative humidity and water vapour pressure, were acquired. All patients readmitted to our department with secondary post-tonsillectomy haemorrhage were recorded. Of 346 patients undergoing tonsillectomy, 32 developed secondary haemorrhage (9.2 per cent). A significant negative correlation was found between secondary haemorrhage rate and the average monthly temperature (max/min) and water vapour pressure (Pearson's correlation = -0.8) (p < or = 0.002). These results suggest that performing tonsillectomy in warmer weather when the water vapour pressure is higher may reduce the secondary haemorrhage rate.


Assuntos
Hemorragia Pós-Operatória/etiologia , Tonsilectomia/efeitos adversos , Tempo (Meteorologia) , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Temperatura Alta , Humanos , Umidade , Masculino , Pessoa de Meia-Idade , Hemorragia Pós-Operatória/prevenção & controle , Estudos Prospectivos , Estações do Ano , Temperatura
13.
J Laryngol Otol ; 119(4): 293-8, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15949084

RESUMO

The value of theatre attendance by undergraduates is uncertain. This study aimed to evaluate the perceived benefits of attending operating theatre sessions during undergraduate otolaryngology attachments. The study comprised a questionnaire survey carried out in a university medical school. Fourth-year medical students were asked to complete a questionnaire at the end of their two-week attachment in otolaryngology. Completed questionnaires were returned by 152 students. The three most common student expectations were to see and learn common ENT operations, to see the anatomy involved and to learn about the disease being operated upon. Sixty per cent of students reported that their expectations had been met. On a Likert scale from 1 (strongly disagree) to 7 (strongly agree), the importance of theatre attendance as part of the curriculum was rated to be 4.7 (95 per cent confidence interval (CI) = 3.7 to 4.2) and the satisfaction of educational needs in operating theatre teaching was rated to be 3.9 (95 per cent CI = 3.7 to 4.2). Students perceived attending otolaryngology theatre sessions to be beneficial. This information is important in the planning of the otolaryngology undergraduate curriculum.


Assuntos
Educação de Graduação em Medicina/métodos , Salas Cirúrgicas , Procedimentos Cirúrgicos Otorrinolaringológicos/educação , Adulto , Atitude do Pessoal de Saúde , Currículo , Humanos , Escócia , Estudantes de Medicina/psicologia , Inquéritos e Questionários , Ensino/normas
14.
Surgeon ; 2(1): 7-14, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15570801

RESUMO

More than 90% of head and neck tumours are squamous cell carcinomas. This review focuses on tumours arising from the mucosal surfaces of the upper aerodigestive tract. We discuss the aetiology, presentation and investigation of these tumours and give special attention to their management which may comprise surgical resection, chemoradiation or combined therapy. The surgical treatment of the clinically positive neck and the somewhat controversial topic of management of the N0 neck are also discussed.


Assuntos
Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/cirurgia , Neoplasias de Cabeça e Pescoço/patologia , Neoplasias de Cabeça e Pescoço/cirurgia , Linfonodos/patologia , Qualidade de Vida , Biópsia por Agulha , Carcinoma de Células Escamosas/mortalidade , Feminino , Neoplasias de Cabeça e Pescoço/mortalidade , Humanos , Imuno-Histoquímica , Excisão de Linfonodo/métodos , Linfonodos/cirurgia , Imageamento por Ressonância Magnética , Masculino , Estadiamento de Neoplasias , Prognóstico , Procedimentos de Cirurgia Plástica/métodos , Medição de Risco , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Procedimentos Cirúrgicos Operatórios/métodos , Análise de Sobrevida , Resultado do Tratamento
15.
J Laryngol Otol ; 118(6): 465-7, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15285868

RESUMO

Retropharyngeal space swelling is a rare occurrence following minor head and neck trauma. Upper airway obstruction is a potentially life-threatening sequela. The authors present a case of retropharyngeal space haematoma following minor blunt head and neck trauma. Management was conservative with gradual spontaneous resolution of the haematoma. The literature is reviewed and the management and treatment principles presented.


Assuntos
Traumatismos Craniocerebrais/complicações , Hematoma/etiologia , Lesões do Pescoço/complicações , Doenças Faríngeas/etiologia , Acidentes por Quedas , Traumatismos Craniocerebrais/diagnóstico por imagem , Traumatismos Craniocerebrais/terapia , Hematoma/diagnóstico por imagem , Hematoma/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Lesões do Pescoço/diagnóstico por imagem , Lesões do Pescoço/terapia , Doenças Faríngeas/diagnóstico por imagem , Doenças Faríngeas/terapia , Radiografia , Remissão Espontânea , Resultado do Tratamento
16.
J Laryngol Otol ; 118(12): 963-71, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15667684

RESUMO

This survey investigates the attitudes of medical and nursing staff towards the daily otolaryngology ward rounds in a teaching hospital. Initial, open-ended questionnaires generated themes from which a structured questionnaire was constructed. Respondents indicated on a Likert scale the extent to which they agreed or disagreed with statements concerning their attitudes towards the ward round. Thirty-five members of staff were surveyed. The overall response rate was 74.3 per cent (n = 26). The majority of staff agreed that the ward round was a constructive use of their time and served to promote team spirit. It allowed for adequate communication between medical and nursing staff but there was uncertainty about the provision of adequate patient communication. The nursing staff agreed that the ward round provided a valuable learning experience. There was uncertainty about this among the medical staff. There was agreement in both groups that patients find the ward round to be reassuring. A significant majority of staff expressed concerns over maintenance of patient confidentiality. These findings could be used to inform changes in the departmental ward round structure. Specific attention should be directed to discussing sensitive issues in a more private setting and maximizing educational opportunities for junior medical staff.


Assuntos
Atitude do Pessoal de Saúde , Corpo Clínico Hospitalar/psicologia , Recursos Humanos de Enfermagem Hospitalar/psicologia , Otolaringologia/organização & administração , Confidencialidade , Educação Médica/normas , Educação em Enfermagem/normas , Hospitais de Ensino , Humanos , Corpo Clínico Hospitalar/educação , Recursos Humanos de Enfermagem Hospitalar/educação , Otolaringologia/educação , Otolaringologia/ética , Equipe de Assistência ao Paciente/organização & administração , Quartos de Pacientes , Relações Profissional-Paciente , Qualidade da Assistência à Saúde , Escócia , Inquéritos e Questionários
17.
Clin Otolaryngol Allied Sci ; 28(5): 411-6, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12969342

RESUMO

The objective of the present study is to propose guidelines to ensure safe practice in teaching centres while allowing endoscopic sinonasal surgery (ESS) training to proceed. A prospective complications audit of ESS procedures was undertaken over a 5-year period (January 1996-December 2000). The results have been used to form specific guidelines for safe and effective ESS training. A total of 500 patients underwent ESS during the 5-year period. The senior author was the main surgeon in 55% of cases with the trainee observing or assisting. A supervised trainee was the main surgeon in 45% of cases. The overall complication rate was 1.2% (n = 6) (i.e. 0.7% for the 815 procedures performed). These were all minor complications. We encountered no major complications in 500 patients over the 5-year period. This audit shows that training need not compromise patient safety provided it is phased and structured. We propose appropriate phases and suggest the minimum requirements for units involved in ESS training.


Assuntos
Endoscopia/efeitos adversos , Endoscopia/educação , Aprendizagem , Procedimentos Cirúrgicos Otorrinolaringológicos/efeitos adversos , Procedimentos Cirúrgicos Otorrinolaringológicos/educação , Complicações Pós-Operatórias/prevenção & controle , Endoscopia/estatística & dados numéricos , Humanos , Internato e Residência/estatística & dados numéricos , Auditoria Médica , Procedimentos Cirúrgicos Otorrinolaringológicos/estatística & dados numéricos , Complicações Pós-Operatórias/epidemiologia , Guias de Prática Clínica como Assunto , Estudos Prospectivos , Reino Unido/epidemiologia
18.
Clin Otolaryngol Allied Sci ; 28(1): 48-50, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12580881

RESUMO

Patients with peri-tonsillar abscess require hospitalization. The aim of this prospective study was to determine whether the admission of patients with peri-tonsillar abscess to the same ward as those undergoing tonsillectomy influences the incidence of secondary post-tonsillectomy haemorrhage. We included all adult patients undergoing in-patient tonsillectomy (n = 183) and all patients with proven peri-tonsillar abscess (n = 46) over a 1-year period. Both patient groups were nursed in the same general otolaryngology ward. The operation dates of those patients who developed secondary post-tonsillectomy haemorrhage were matched to the dates when patients with peri-tonsillar abscess were admitted. Out of the 71 patients who had tonsillectomy on days when patients with peri-tonsillar abscess were admitted, 10 developed secondary haemorrhage. Out of the 112 patients who had tonsillectomy on days when no one in the ward had peri-tonsillar abscess, 16 developed secondary haemorrhage. No difference was demonstrated (chi2 = 0.0014, P > 0.05). In this study, admission of patients with peri-tonsillar abscess to a general otolaryngology ward does not influence the incidence of secondary post-tonsillectomy haemorrhage in patients undergoing elective surgery.


Assuntos
Departamentos Hospitalares , Otolaringologia , Admissão do Paciente/estatística & dados numéricos , Abscesso Peritonsilar/reabilitação , Abscesso Peritonsilar/cirurgia , Hemorragia Pós-Operatória , Tonsilectomia/métodos , Adolescente , Adulto , Idoso , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Tempo de Internação/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
19.
Health Educ Behav ; 28(3): 290-305, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11380050

RESUMO

The Anti-Cancer Council of Victoria has been running sun protection programs for more than 20 years: Slip! Slop! Slap! from 1980 to 1988 and SunSmart from 1988 to the present. The Victorian Health Promotion Foundation has provided funding for the SunSmart program for the past 13 years. These programs have played an important role in changing the whole society's approach to the sun and have resulted in marked reductions in sun exposure. This article describes the social, political, economic, and organizational context within which these programs developed. Then 10 areas are discussed that illustrate a critical aspect of the development and implementation of this successful systemwide health promotion program. These areas focus on key aspects of the context within which the program operates and on issues that derive from the experience of implementing program strategies. In summary, the success of the two programs is described as having been built on two key foundations: the vital integration of research and evaluation, on one hand, and a strong basis of consistency and continuity, on the other.


Assuntos
Exposição Ambiental/prevenção & controle , Promoção da Saúde/organização & administração , Neoplasias Cutâneas/prevenção & controle , Luz Solar , Adolescente , Adulto , Criança , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Implementação de Plano de Saúde , Humanos , Masculino , Modelos Educacionais , Desenvolvimento de Programas , Neoplasias Cutâneas/etiologia , Luz Solar/efeitos adversos , Vitória
20.
J Bacteriol ; 182(19): 5359-64, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10986237

RESUMO

The periplasmic protein FepB of Escherichia coli is a component of the ferric enterobactin transport system. We overexpressed and purified the binding protein 23-fold from periplasmic extracts by ammonium sulfate precipitation and chromatographic methods, with a yield of 20%, to a final specific activity of 15,500 pmol of ferric enterobactin bound/mg. Periplasmic fluid from cells overexpressing the binding protein adsorbed catecholate ferric siderophores with high affinity: in a gel filtration chromatography assay the K(d) of the ferric enterobactin-FepB binding reaction was approximately 135 nM. Intrinsic fluorescence measurements of binding by the purified protein, which were more accurate, showed higher affinity for both ferric enterobactin (K(d) = 30 nM) and ferric enantioenterobactin (K(d) = 15 nM), the left-handed stereoisomer of the natural E. coli siderophore. Purified FepB also adsorbed the apo-siderophore, enterobactin, with comparable affinity (K(d) = 60 nM) but did not bind ferric agrobactin. Polyclonal rabbit antisera and mouse monoclonal antibodies raised against nearly homogeneous preparations of FepB specifically recognized it in solid-phase immunoassays. These sera enabled the measurement of the FepB concentration in vivo when expressed from the chromosome (4,000 copies/cell) or from multicopy plasmids (>100,000 copies/cell). Overexpression of the binding protein did not enhance the overall affinity or rate of ferric enterobactin transport, supporting the conclusion that the rate-limiting step of ferric siderophore uptake through the cell envelope is passage through the outer membrane.


Assuntos
Proteínas de Transporte/metabolismo , Enterobactina/metabolismo , Proteínas de Escherichia coli , Compostos Férricos/metabolismo , Proteínas de Membrana Transportadoras , Proteínas Periplásmicas , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/isolamento & purificação , Cromatografia de Afinidade/métodos , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Radioisótopos de Ferro/metabolismo , Camundongos , Periplasma/metabolismo , Ligação Proteica , Coelhos , Sideróforos/metabolismo
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