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1.
Int J Cancer ; 153(2): 399-406, 2023 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-36866965

RESUMO

Human papillomavirus (HPV) vaccine effectiveness may differ between settings. Here we present the first real-world effectiveness study of HPV vaccination on high-grade cervical lesions from Norway, among women who received HPV vaccine outside the routine program. We performed an observational study of all Norwegian women born 1975 to 1996 and retrieved individual data from nationwide registries on HPV vaccination status and incidence of histologically verified high-grade cervical neoplasia during 2006 to 2016. We estimated the incidence rate ratio (IRR) and 95% confidence intervals (CI) for vaccination vs no vaccination by Poisson regression stratified by age at vaccination <20 years and ≥20 years. The cohort consisted of 832 732 women, of which 46 381 (5.6%) received at least one dose of HPV vaccine by the end of 2016. The incidence rate of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) increased with age regardless of vaccination status and was highest at age 25 to 29, at 637/100 000 among unvaccinated women, 487/100 000 among women vaccinated before age 20 and 831/100 000 among women vaccinated at age 20 or older. The adjusted IRR of CIN2+ between vaccinated and unvaccinated women was 0.62 (95% CI: 0.46-0.84) for women vaccinated below age 20, and 1.22 (95% CI: 1.03-1.43) for women vaccinated at age 20 or older. These findings indicate that HPV vaccination among women too old to be eligible for routine HPV vaccination is effective among women who are vaccinated below age 20 but may not have the desired impact among women who are vaccinated at age 20 or older.


Assuntos
Infecções por Papillomavirus , Vacinas contra Papillomavirus , Displasia do Colo do Útero , Neoplasias do Colo do Útero , Feminino , Humanos , Adulto , Adulto Jovem , Coorte de Nascimento , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/prevenção & controle , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/prevenção & controle , Neoplasias do Colo do Útero/patologia
2.
J Pediatr Nurs ; 71: e154-e164, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37270387

RESUMO

PROBLEM: The transition from paediatric-centred to adult healthcare services in adolescent solid organ transplantation recipients is a period of increased risk and vulnerability, the issues related to healthcare transition have become key concerns to the healthcare community. ELIGIBILITY CRITERIA: Qualitative studies of any design and qualitative components of mixed method studies that explored the experiences of healthcare transition among adolescent solid organ transplant recipients, parents, and healthcare professionals were included. SAMPLE: Nine articles were finalised and included in the review. METHODS: A systematic review of qualitative studies was conducted. Databases searched were Scopus, PsycINFO, EMBASE, Web of Science, PubMed, CINAHL and ProQuest Dissertations and Theses. Studies published between the inception of respective database and December 2022 inclusive were considered. A three-step inductive thematic synthesis method outlined by Thomas and Harden was used to form descriptive themes and the 10-item Joanna Briggs Institute Critical Appraisal Checklist was utilised to appraise the quality of included articles. RESULTS: Two hundred and twenty studies were screened, and 9 studies published between 2013 and 2022 were included. Five analytical themes were generated: 'the struggle of being an adolescent with a transplant'; 'perceptions of transition'; 'the role of parents'; 'lack of transition readiness' and 'the need for better support'. CONCLUSIONS: Adolescent solid organ transplant recipients, parents, and healthcare professionals faced multiple challenges in the healthcare transition. IMPLICATIONS: Future interventions and health policies should provide targeted intervention strategies that address the barriers present in the healthcare transition to facilitate the optimization of the youth healthcare transition.


Assuntos
Transplante de Órgãos , Transição para Assistência do Adulto , Adulto , Humanos , Criança , Adolescente , Pessoal de Saúde , Pais , Pesquisa Qualitativa , Atenção à Saúde
3.
Ann Plast Surg ; 86(3S Suppl 2): S239-S243, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33346557

RESUMO

OBJECTIVES: The aims of the study were to explore the application of endoscopy in the correction of septal deviation and nasal skeletal deviation in crooked nose deformity and, using multiple evaluation methods, to investigate the effect of endoscopy-assisted 1-stage surgery in restoring crooked nose airway function and aesthetic morphology. METHODS: From March 2015 to March 2018, 45 patients with nasal septum and skeletal deviation were treated with endoscopy-assisted septoplasty simultaneously with rhinoplasty. The follow-up period was at least 8 months. Treatment effects were evaluated both objectively and subjectively using various methods. RESULTS: All cases showed certain degree of airway function and nose morphology improvement. In patients with abnormal nasal ventilation, the volume and minimal cross-sectional area increased significantly after the surgery (t = 2.470 and 3.134, respectively, P < 0.05). External nose deviation distance measured on 3-dimensional models decreased significantly from 3.230 ± 1.661 mm to 1.997 ± 1.037 mm after the surgery (t = 3.772, P < 0.05). Patients visual analog scale score of nasal patency and nose morphology were significantly improved (t = 5.795 and 7.187, respectively, P < 0.05). Overall patient satisfaction was 100%, and no complication (nasal septal perforation, nasal cavity synechia, etc) was reported. CONCLUSIONS: Septal deviation combined with external nose deflection can be corrected by endoscopy-assisted rhinoplasty and septoplasty simultaneously, to achieve 1-stage improvement of crooked nose morphology and nasal airway function. This approach has the advantages of minimal invasion, clear surgery vision, less pain, and shorter recover time. It has fewer complication and better outcomes and worth clinical promotion and application.


Assuntos
Obstrução Nasal , Deformidades Adquiridas Nasais , Rinoplastia , Endoscopia , Estética , Humanos , Obstrução Nasal/cirurgia , Septo Nasal/cirurgia , Nariz/cirurgia , Deformidades Adquiridas Nasais/cirurgia , Resultado do Tratamento
4.
Acta Neurol Scand ; 139(3): 276-283, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30428122

RESUMO

OBJECTIVE: This study is aimed to access the efficacy and safety of combination therapy of flunarizine plus transcutaneous supraorbital neurostimulation (tSNS) compared with either flunarizine or tSNS alone for migraine prophylaxis. METHODS: Patients with episodic migraine were enrolled and randomized into 3 groups. Flunarizine 5 mg per day, or tSNS for 20 minutes daily or combination of both were prescribed consecutively for 3 months. The primary outcome measures were changes in migraine days and 50% responder rate of monthly migraine days. Secondary outcome measures were the changes in migraine intensity and intake of rescue medication. Finally, satisfaction to treatment and adverse effect were evaluated as well. RESULTS: A total of 154 were randomized and included in the analysis. After 3 months, the monthly migraine days were decreased in 3 groups and more significant in the combination group. The 50% responder rate was significantly higher (78.43%) in the combination therapy than monotherapy of flunarizine (46.15%) or tSNS (39.22%) alone. Greater reduction of migraine intensity and intake of rescue medication was observed in combination group. There was no difference of adverse events between flunarizine group and combination group (P = .89). CONCLUSION: Adding tSNS to flunarizine can improve the therapeutic efficacy of migraine prophylaxis without increasing the adverse effects. In addition, tSNS is effective and safe for migraine treatment and can be a valid option for migraineurs who are reluctant to take oral medications or for patients who experience a low-migraine frequency and/or intensity that prophylactic therapy is not indicated but desire to acquire medical intervention.


Assuntos
Terapia Combinada/métodos , Flunarizina/administração & dosagem , Transtornos de Enxaqueca/prevenção & controle , Estimulação Elétrica Nervosa Transcutânea/métodos , Vasodilatadores/administração & dosagem , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
6.
Radiology ; 260(1): 224-31, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21493792

RESUMO

PURPOSE: To investigate whether short-term, intensive lipid therapy leads to changes in microvascular characteristics, as measured by using dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for this HIPAA-compatible study. Subjects with established coronary artery disease or carotid artery stenosis of 15% or greater determined by using ultrasonography and with levels of apolipoprotein B of 120 mg/dL (1.2 g/L) or greater were enrolled in an ongoing study (clinical trial NCT00715273). All received intensive lipid therapy to achieve targeted high- and low-density lipoprotein cholesterol levels and underwent serial serum monitoring including high-sensitivity C-reactive protein (HsCRP) level measurements. Carotid artery MR imaging examinations including morphologic and DCE MR images were obtained at baseline and 1 year after treatment. In subjects with advanced lesions (>2 mm thick), MR image analysis was performed, including measurement of lipid-rich necrotic core size and kinetic modeling of DCE MR images to assess changes in the transfer constant (K(trans)). The differences in K(trans) between baseline and 1-year follow-up were compared by using the Wilcoxon signed rank test, and associations were assessed by using the Spearman rank correlation coefficient. RESULTS: Twenty-eight subjects with interpretable DCE MR imaging results at both baseline and 1-year follow-up were included. After 1 year of treatment, a significant reduction was found in mean K(trans) (0.085 min(-1) ± 0.037 [standard deviation] to 0.067 min(-1) ± 0.028, P = .02). Reduction in K(trans) was not significantly correlated with observed reductions in lipid-rich necrotic core size or reductions in HsCRP level. CONCLUSION: These findings suggest that DCE MR imaging may be a useful imaging method for the assessment of the therapeutic response of the vasa vasorum in patients with atherosclerotic plaque.


Assuntos
Aterosclerose/tratamento farmacológico , Aterosclerose/patologia , Doenças das Artérias Carótidas/tratamento farmacológico , Doenças das Artérias Carótidas/patologia , Ácidos Heptanoicos/uso terapêutico , Imageamento por Ressonância Magnética/métodos , Pirróis/uso terapêutico , Vasa Vasorum/patologia , Adulto , Idoso , Anticolesterolemiantes/uso terapêutico , Atorvastatina , Meios de Contraste , Feminino , Gadolínio DTPA , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Resultado do Tratamento
7.
Childs Nerv Syst ; 27(4): 565-73, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20922396

RESUMO

PURPOSE: Acute care utilization patterns are not well described but may help inform care coordination and treatment for pediatric stroke. The Kids Inpatient Database was queried to describe demographics and clinical characteristics of children with stroke, compare acute care utilization for hemorrhagic vs. ischemic stroke and Children's vs. non-Children's Hospitals, and identify factors associated with aggressive care and in-hospital mortality. METHODS: Using a retrospective cohort of children hospitalized with stroke, demographics, predisposing conditions, and intensive (mechanical ventilation, advanced monitoring, and blood product administration) or aggressive (pharmacological therapy and/or invasive interventions) care were compared by stroke and hospital types. Factors associated with aggressive care or in-hospital mortality were explored using logistic regression. RESULTS: Hemorrhagic stroke comprised 43% of stroke discharges, was more common in younger children, and carried greater mortality. Ischemic stroke was more common in older children and more frequently associated with a predisposing condition. Rates of intensive and aggressive care were low (30% and 15%), similar by stroke type, and greater at Children's Hospitals. Older age, hemorrhagic stroke, predisposing condition, and treatment at a Children's Hospital were associated with aggressive care. Hemorrhagic stroke and aggressive care were associated with in-hospital mortality. CONCLUSIONS: Acute care utilization is similar by stroke type but both intensive and aggressive care are more common at Children's Hospitals. Mortality remains relatively high after pediatric stroke. Widespread implementation of treatment guidelines improved outcomes in adult stroke. Adoption of recently published treatment recommendations for pediatric stroke may help standardize care and improve outcomes.


Assuntos
Cuidados Críticos/estatística & dados numéricos , Hospitais/estatística & dados numéricos , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/terapia , Fatores Etários , Criança , Pré-Escolar , Bases de Dados Factuais , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Procedimentos Neurocirúrgicos/estatística & dados numéricos , Respiração Artificial/estatística & dados numéricos , Terapia Trombolítica/estatística & dados numéricos
8.
Artigo em Inglês | MEDLINE | ID: mdl-32121272

RESUMO

The dark adaptation of drivers' eyes at a tunnel entrance seriously affects traffic safety. This can be improved by the design of tunnel lighting. Light-Emitting Diode (LEDs) have been applied as a new type of luminaire in tunnel lighting in recent years, but at present, there are few studies on the influence of color rendering of LEDs on tunnel traffic safety, and there is no explicit indicator for the selection of appropriate color rendering parameters in tunnel lighting specifications, which has aroused researchers' concern. In this article, several new color rendering evaluation indexes were compared, and as a result, it is considered that CRI2012 (a color difference-based color rendering index) is more suitable for evaluating the color rendering of LEDs used at tunnel entrances. The dark adaptation phenomenon was simulated in the laboratory. Four CRI2012s, three color temperatures and eight colored targets were used in the experiments. The results showed that yellow, silver and white can provide shorter reaction times, while red and brown lead to longer reaction times, which can provide a reference for the design of road and warning signs at tunnel entrances. The effect of target color on reaction time was greater than that of color rendering. Under most target colors, the higher the CRI2012, the shorter the reaction time. When designing the color rendering of the LEDs at a tunnel entrance, the value should thus be as large as possible (close to 100), and a lower color temperature value (about 2800 K) should be selected. This paper provides technical support for tunnel lighting design and a reference for tunnel lighting specifications, which is of significance to improve driving safety and avoid traffic accidents in highway tunnels.


Assuntos
Condução de Veículo , Cor , Adaptação à Escuridão , Iluminação , Acidentes de Trânsito/prevenção & controle , Humanos
9.
World J Clin Cases ; 8(11): 2173-2180, 2020 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-32548147

RESUMO

BACKGROUND: The Helicobacter pylori (H. pylori) infection rate in China is approximately 50%. H. pylori is a pathogenic factor of peptic ulcer and chronic gastritis. In addition, H. pylori infection may also be associated with a variety of cardiovascular diseases in elderly people, such as arteriosclerosis, coronary heart disease, and cerebral infarction, having deleterious effect on their health. With the aging of the population, the disease characteristics of the elderly population have been increasingly valued by the whole society. We conducted an epidemiological survey of H. pylori infection among elderly people in Beijing to provide a basis for health management of H. pylori infection. AIM: To understand the epidemiological characteristics of H. pylori infection in elderly people in Beijing. METHODS: A total of 1090 elderly people aged more than 60 years from different parts of Beijing (urban and rural areas) were selected using the random cluster sampling method. Structured questionnaires were completed during home visits and the 13C-urea breath test was conducted for H. pylori detection. RESULTS: The prevalence of H. pylori infection was 46.5% (507/1090). The infection rate in men was 51.8%, which was significantly higher than that in women (42.5%; P < 0.05). The H. pylori infection rate in illiterate people was significantly higher than that in literate persons (53.5% vs 44.8%, P < 0.05). The total infection rate of H. pylori gradually increased with age and the difference was statistically significant (P < 0.01). The H. pylori infection rate in smokers was significantly higher than that in non-smokers and those who had quit smoking (P < 0.05). CONCLUSION: The prevalence of H. pylori infection among elderly people is 46.5% and the infection rate gradually increases with age. Sex, education level, age, and smoking were determined to be H. pylori infection risk factors. The relationship of H. pylori infection with region, occupation, drinking, and diet structure needs to be further studied.

10.
Clin Pediatr (Phila) ; 57(5): 580-583, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-28990434

RESUMO

The aims of this study were to investigate the effect of neuromuscular electrical stimulation (NMES) combined with strengthening exercise on movement in children with spastic cerebral palsy (CP). One hundred children with spastic CP were randomly divided into a treatment group (NMES and strengthening exercise, n = 50) and a control group (only NMES, n = 50). We compared the Comprehensive Spasticity Scale (CSS) score, Gross Motor Function Measure (GMFM) score, and walking speed before treatment and 6 weeks and 3 months after treatment between the 2 groups. There was no difference in CSS score between the treatment and control groups before the therapy (12.0 ± 3.4 vs 12.3 ± 3.6), which decreased much more in the treatment group after 6 weeks (7.6 ± 3.0 vs 9.5 ± 2.8) and 3 months (7.4 ± 2.4 vs 9.4 ± 2.6) with significant differences ( P < .05). No difference in GMFM score was observed between the treatment and control groups before the therapy (44.5 ± 13.2 vs 44.0 ± 12.6), which increased much more in the treatment group after 6 weeks (70.6 ± 15.2 vs 56.7 ± 14.3) and 3 months (71.0 ± 16.4 vs 58.0 ± 15.6) with significant differences ( P < .05). The walking speed improved over time, which was the same before the treatment (0.43 ± 0.13 m/s vs 0.45 ± 0.14 m/s), and was significantly greater in the treatment group than that in the control group (6 weeks: 0.69 ± 0.15 m/s vs 0.56 ± 0.12 m/s, P < .05; 3 months: 0.72 ± 0.17 m/s vs 0.57 ± 0.18 m/s, P < .05). NMES combined with strengthening exercise was more effective than NMES alone in the recovery of spastic CP.


Assuntos
Paralisia Cerebral/terapia , Terapia por Estimulação Elétrica/métodos , Terapia por Exercício/métodos , Força Muscular/fisiologia , Criança , Terapia Combinada , Feminino , Humanos , Masculino , Espasticidade Muscular/terapia , Resultado do Tratamento
11.
Medicine (Baltimore) ; 97(6): e9548, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29419662

RESUMO

OBJECTIVE: The controversy remains as to whether immediate prosthetic breast reconstruction with postmastectomy radiation therapy (PMRT) is associated with acceptable complications and aesthetic outcomes. The aim of this meta-analysis was to provide a pooled analysis of comparative clinical studies that evaluated breast cancer patients who were treated with a mastectomy and an immediate prosthetic breast reconstruction to compare the complications and satisfaction of those who underwent or did not undergo PMRT. METHODS: According to the recommendations of the Cochrane Collaboration, we established a rigorous study protocol. We performed a systematic electronic search of the PubMed and Embase databases to identify articles for inclusion in our meta-analysis. Reconstruction failure, overall complications, capsular contracture, and patient satisfaction were analyzed individually. RESULTS: Fifteen controlled trials were included, comprising 5314 patients (1069 PMRT vs 4245 non-PMRT). Primary outcomes revealed a statistically significant increase in overall complications [odds ratio (OR) 3.45; 95% confidence interval (95% CI) 2.62-4.54; P < .00001], reconstruction failure (OR: 2.59; 95% CI 1.46-4.62; P = .001), and capsular contracture (OR: 5.26, 95% CI: 2.73-10.13, P < .00001) after receiving PMRT. CONCLUSION: Our review found that PMRT for patients who underwent immediate implant-based breast reconstruction led to higher risks of reconstruction failure, overall complications, and capsular contracture. However, it is still the standard adjuvant therapy for mastectomy patients who have opted for immediate implant-based breast reconstruction.


Assuntos
Implante Mamário/métodos , Neoplasias da Mama/radioterapia , Radioterapia Adjuvante/métodos , Neoplasias da Mama/cirurgia , Feminino , Humanos , Mastectomia/métodos , Resultado do Tratamento
12.
Photodiagnosis Photodyn Ther ; 12(1): 92-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25479094

RESUMO

BACKGROUND: Photodynamic therapy (PDT) is a successful treatment for non-melanoma skin cancers in clinical practice. More and more doctors use PDT to cure the patients with skin cancer, especially in the elder. The purpose of this study was to evaluate the efficacy and safety of topical PDT using aminolevulinic acid (5-ALA) in the treatment of Extramammary Paget's disease (EMPD) and its role in surgical improvements. METHODS: A total of 38 cases were included in this study. Lesions were located in the scrotum and the penis. Thirty-one cases had surgical resection of the lesions followed by ALA-PDT (combination of PDT and surgery group). Seven cases received ALA-PDT without receiving surgical resection because the surgery is extremely difficult or the patients refused surgery (simple PDT group). Each tumor lesion was irradiated with 120J/cm(2) using a 635-nm laser for 15min. A total of 3 times of assisted ALA-PDT was applied after surgery. RESULTS: In the combination group, there was no recurrence in 6 months after treatment. In another group, recurrence occurred in 1 case in 6 months. All patients were able to complete the treatment protocol, with well cosmetic results and no moderate adverse reactions. CONCLUSIONS: As an assistive therapy after tumor resection, ALA-PDT can reduce the excision range of the tumor lesions and will play more important role in the treatment of EMPD.


Assuntos
Ácido Aminolevulínico/administração & dosagem , Procedimentos Cirúrgicos Dermatológicos , Doença de Paget Extramamária/terapia , Neoplasias Cutâneas/terapia , Administração Cutânea , Idoso , Idoso de 80 Anos ou mais , Ácido Aminolevulínico/efeitos adversos , Terapia Combinada/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Paget Extramamária/patologia , Radiossensibilizantes/administração & dosagem , Radiossensibilizantes/efeitos adversos , Neoplasias Cutâneas/patologia , Resultado do Tratamento
13.
Chin Med J (Engl) ; 125(11): 1899-902, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22884050

RESUMO

BACKGROUND: Roux-en-Y gastric bypass (GBP) is the main surgical procedure used in type 2 diabetes. The objective of this study was to evaluate the different types of GBP in treatment of type 2 diabetes. METHODS: Patients with type 2 diabetes were randomly divided into two groups: those who underwent gastrojejunal loop anastomosis bypass and those who underwent gastrojejunal Roux-en-Y bypass. Blood glucose alterations, operation time, and operation complications were observed. RESULTS: Gastrojejunal loop anastomosis bypass and gastrojejunal Roux-en-Y bypass were both effective in the treatment of selected patients with type 2 diabetes. Compared with gastrojejunal Roux-en-Y bypass, gastrojejunal loop anastomosis bypass had the advantages of easier implementation, shorter operation time, and fewer operation complications. CONCLUSIONS: Gastrojejunal loop anastomosis is effective in treatment of type 2 diabetes. It is safe, easy to implement, and worthy of clinical popularization.


Assuntos
Diabetes Mellitus Tipo 2/cirurgia , Derivação Gástrica/métodos , Adulto , Anastomose em-Y de Roux , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento
17.
Biometals ; 17(2): 99-104, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15088934

RESUMO

The ability of exochelin MN and three synthetic analogues to promote the growth of various strains of mycobacteria and Gram-negative bacteria was investigated. The results indicated that growth promotion ability of these compounds depends either on ligand exchange with mycobactin or on the exochelin permease. Despite stronger iron complexing capacity, the structural analogues showed weaker growth promotion ability than exochelin MN, which further supported our hypothesis of pH-dependent iron(III)-release of exochelin MN.


Assuntos
Bactérias Gram-Negativas/efeitos dos fármacos , Substâncias de Crescimento/farmacologia , Mycobacterium/efeitos dos fármacos , Peptídeos Cíclicos/farmacologia , Bactérias Gram-Negativas/crescimento & desenvolvimento , Substâncias de Crescimento/metabolismo , Ferro/metabolismo , Mycobacterium/crescimento & desenvolvimento , Peptídeos Cíclicos/metabolismo , Sideróforos/metabolismo
18.
s.l; s.n; 2003. 10 p. tab, graf.
Não convencional em Inglês | Sec. Est. Saúde SP, HANSEN, Hanseníase, SESSP-ILSLACERVO, Sec. Est. Saúde SP | ID: biblio-1241155

RESUMO

The coordination chemistry of an extracellular siderophore produced by Mycobacterium neoaurum, exochelin MN (ExoMN), is reported along with its pK(a) values, Fe(III) and Fe(II) chelation constants, and aqueous solution speciation as determined by spectrophotometric and potentiometric titration techniques. Exochelin MN is of particular interest as it can efficiently transport iron into pathogenic M. leprae, which is responsible for leprosy, in addition to its own parent cells. The Fe(III) coordination properties of ExoMN are important with respect to understanding the Fe(III) acquisition and uptake mechanism in pathogenic M. leprae, as the siderophores from this organism are very difficult to isolate. Exochelin MN has two hydroxamic acid groups and an unusual threo-beta-hydroxy-l-histidine available for Fe(III) chelation. The presence of threo-beta-hydroxy-l-histidine gives rise to a unique mode of Fe(III) coordination. The pK(a) values for the two hydroxamic acid moieties, the histidine imidazole ring and the alkylammonium groups on ExoMN, correspond well with the literature values for these moieties. Proton-dependent Fe(III)- and Fe(II)-ExoMN equilibrium constants were determined using a model involving sequential protonation of the Fe(III)- and Fe(II)-ExoMN complexes. These data were used to develop a model whereby deprotonation reactions on the surface of the complex in the second coordination shell result in first coordination shell isomerization. The overall formation constants were calculated: log beta(110) = 39.12 for Fe(III)-ExoMN and 16.7 for Fe(II)-ExoMN. The calculated pFe value of 31.1 is one of the highest among all siderophores and their synthetic analogues and indicates that ExoMN is thermodynamically capable of removing Fe(III) from transferrin. The E(1/2) for the Fe(III)ExoMN/Fe(II)ExoMN(-) couple was determined to be -595 mV from quasi-reversible cyclic voltammograms at pH = 10.8, and the pH-dependent E(1/2) profile was used to determine the Fe(II)-ExoMN protonation constants.


Assuntos
Cinética , Compostos Ferrosos/química , Compostos Férricos/química , Concentração de Íons de Hidrogênio , Espectrofotometria Ultravioleta , Mycobacterium/química , Peptídeos Cíclicos/química , Potenciometria , Quelantes de Ferro/química
19.
Shanghai; STD; 2001. 87 p. ilus, tab.
Monografia em Português | Sec. Est. Saúde SP, HANSEN, Hanseníase, SESSP-ILSLACERVO, Sec. Est. Saúde SP | ID: biblio-1241855
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