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Background: Participating in physical activity (PA) can be challenging for persons with chronic and significant lung disease due to the multifaceted disruptive effects of their symptoms and variable disease course. Objectives: Our study investigates a novel approach to increasing PA by collaboratively and adaptively developing a Tai Chi (TC) class for and by persons with lung diseases and explores participants' perceptions of their experiences in the co-developed TC class. Methods: We initiated a collaboration between the Interstitial Lung Disease (ILD) Collaborative and the Tai Chi Foundation to develop a TC class appropriate for persons with ILD and other lung diseases. The TC class was offered online, during the early phases of the COVID-19 pandemic, when pulmonary patients were isolated socially. TC class sessions were held twice weekly for 12 weeks with 12 participants. Ethnographic field methods were used to collect observations and conduct interviews with teachers and students. The Social Ecological Model (SEM) for understanding factors in intrapersonal, interpersonal, social, and organizational contexts was used to explore ways in which wellness practices, particularly those involving changes in health behaviors, can be collaboratively conceived, and developed by persons with the lived experience of illness and community organizations that are sensitive to their personal and social contexts. The constant comparative method was used for data analysis. Results: Our findings include the importance of (1) creating a supportive class environment, characterized by interactive and reciprocal relationships among students and teachers; (2) alternating segments of movement and meditation to avoid fatigue and breathlessness; (3) cultivating sensory awareness and body trust, resting when needed and rejoining the movements when ready; (4) increasing the capacity to meditate through deepening presence and renewing the vital connection with inner and outer sources of energy; (5) reducing, through meditative movement, the persistent anxiety, isolation, and sense of loss that accompany chronic disease diagnosis and progression. Conclusion: We documented a collaboration between the TC and pulmonary communities to design a TC class for persons with chronic and significant lung disease. We employed the SEM to provide insights into how teachers, informed by their students, can use effective pedagogical skills to create core curricula with modifications appropriate for a specific population.
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Ischemia/reperfusion (I/R) injury unavoidably occurs during hepatic resection and transplantation. Aged livers poorly tolerate I/R during surgical treatment. Although livers have a powerful endogenous inhibitor of calpains, calpastatin (CAST), I/R activates calpains, leading to impaired autophagy, mitochondrial dysfunction, and hepatocyte death. It is unknown how I/R in aged livers affects CAST. Human and mouse liver biopsies at different ages were collected during in vivo I/R. Hepatocytes were isolated from 3-month- (young) and 26-month-old (aged) mice, and challenged with short in vitro simulated I/R. Cell death, protein expression, autophagy, and mitochondrial permeability transition (MPT) between the two age groups were compared. Adenoviral vector was used to overexpress CAST. Significant cell death was observed only in reperfused aged hepatocytes. Before the commencement of ischemia, CAST expression in aged human and mouse livers and mouse hepatocytes was markedly greater than that in young counterparts. However, reperfusion substantially decreased CAST in aged human and mouse livers. In hepatocytes, reperfusion rapidly depleted aged cells of CAST, cleaved autophagy-related protein 5 (ATG5), and induced defective autophagy and MPT onset, all of which were blocked by CAST overexpression. Furthermore, mitochondrial morphology was shifted toward an elongated shape with CAST overexpression. In conclusion, CAST in aged livers is intrinsically short-lived and lost after short I/R. CAST depletion contributes to age-dependent liver injury after I/R.
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Proteínas de Ligação ao Cálcio/metabolismo , Hepatócitos/metabolismo , Hepatopatias/metabolismo , Fígado/metabolismo , Traumatismo por Reperfusão/metabolismo , Fatores Etários , Animais , Autofagia , Proteína 5 Relacionada à Autofagia/metabolismo , Proteínas de Ligação ao Cálcio/genética , Calpaína/metabolismo , Morte Celular , Células Cultivadas , Modelos Animais de Doenças , Regulação da Expressão Gênica , Hepatócitos/patologia , Humanos , Fígado/patologia , Hepatopatias/genética , Hepatopatias/patologia , Masculino , Camundongos Endogâmicos C57BL , Mitocôndrias Hepáticas/genética , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/patologia , Transdução de Sinais , Fatores de TempoRESUMO
OBJECTIVE: The objective of this review was to identify and describe the factors influencing diabetes self-management in adults by summarizing the available evidence concerning their types, categories, and relative importance. INTRODUCTION: A wide range of factors, acting simultaneously, influence diabetes self-management and interfere with its actual application by patients. There is a variety of systematic reviews of these factors; however, a more thorough examination of their influences was lacking. INCLUSION CRITERIA: Systematic reviews of qualitative or quantitative literature focusing on factors influencing adult diabetes self-management in general or on individual behaviors (ie, management of oral antidiabetic medication and insulin injections, self-monitoring of blood glucose, foot care, healthy eating, regular exercise, and smoking cessation) will be included. METHODS: We performed an extensive search of 11 bibliographic databases, including gray literature, up to June 2019. Quantitative and qualitative findings were summarized separately and labeled according to their types (eg, facilitator/barrier, strength and direction of association), categories (eg, demographic, social), and frequency of occurrence. RESULTS: We identified 51 types of factors within 114 systematic reviews, which mostly addressed medication-taking behavior. Thirty-two (62.7%) factors were reported in both qualitative and quantitative literature. The predominant influences were psychological factors and behavioral attributes/skills factors. The most frequently reported facilitators of diabetes self-management were motivation to diabetes self-management, a favorable attitude to diabetes self-management, knowledge about the disease, medication and behaviors associated with diabetes self-management, skills, and self-efficacy/perceived behavioral control. The predominant barriers were the presence of depression, and polypharmacy or drug regimen complexity. The demographic factor of female sex was frequently reported for its negative influence on diabetes self-management, whereas older age was a positive factor. The social/cultural and physical environment were the least-studied categories. Other factors such as social support from family, friends, or networks; interventions led by health professionals; and a strong community environment with good social services favoring diabetes self-management were reported as major facilitators of diabetes self-management. CONCLUSIONS: Essential components of interventions to promote effective diabetes self-management should aim to help adults manage the effects of specific factors related to their psychological and practical self-management experience. Screening for depression, in particular, should become an integral part of the support for adult diabetes self-management, as depression is a particular obstacle to the effectiveness of diabetes self-management. Future studies should more deeply examine the influence of factors identified in the sociocultural and physical environment categories. Research should properly consider and invest efforts in strengthening social support and innovative community care approaches, including pharmacist- and nurse-led care models for encouraging and improving adult diabetes self-management. Finally, researchers should examine non-modifiable factors - age, sex, or socioeconomic status - in the light of factors from other categories in order to deepen understanding of their real-world patterns of action on adult diabetes self-management. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO CRD42018084665.
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Diabetes Mellitus , Autogestão , Adulto , Idoso , Diabetes Mellitus/tratamento farmacológico , Feminino , Comportamentos Relacionados com a Saúde , Pessoal de Saúde , Humanos , Revisões Sistemáticas como AssuntoRESUMO
OBJECTIVE: The objective of this review was to gain a better understanding of the interprofessional collaboration between health care professionals from the patients' point of view during hospitalisation; the influence of interprofessional collaboration on patient care, safety, and well-being; and patients' perspectives of their role in the interprofessional collaboration process. INTRODUCTION: Interprofessional collaboration is a key factor in improving patient health care outcomes and safety through better communication between health care professionals, better teamwork, and better care coordination. However, implementing interprofessional collaboration in the clinical setting can prove complex. Patients are increasingly interested in becoming partners within the health care system. They have the potential to contribute to their own safety and to observe professionals during the care process, thus gaining a better understanding of the interprofessional collaboration process and facilitating changes in the behavior of health care professionals. INCLUSION CRITERIA: This review considered qualitative research and mixed-method studies. Participants were hospitalized patients. Studies were included when they explored i) patients' perceptions of interprofessional collaboration, ii) the influence of interprofessional collaboration on patients' care, safety, or well-being, or iii) patients' perceptions of their own role in interprofessional collaboration. Qualitative studies focusing only on the care process or families' points of view were excluded. METHODS: Searches of six databases including MEDLINE, CINAHL, Embase, Web of Science, PsycINFO, and Sociological Abstract, limited to English, French, and German were conducted from March 2017 to June 2018. Assessment of methodological quality of studies was performed using the JBI Qualitative Assessment and Review Instrument. Data were extracted using the standardized data extraction tool from JBI. Data synthesis following the JBI approach of meta-aggregation was performed. The level of confidence for each synthesized finding was established based on ConQual. RESULTS: A total of 22 studies were included, which resulted in 89 findings and 24 categories. Eight synthesized findings were generated: patients' perceptions of interprofessional collaboration based on personal experiences and observations; patients' experiences with effective or ineffective interprofessional communication; patients' experience with power imbalance and paternalistic attitudes; patients' perceptions of key factors for a confident relationship with the interprofessional health care team; patients' need for comprehension of discussions between health care professionals; patients' perceptions of their role in an interprofessional health care team; patients' perceptions of opportunities for empowerment in interprofessional health care teams; and patients' need for humanizing care from interprofessional health care teams. The level of confidence of synthesized findings varied from low to moderate according to ConQual. CONCLUSIONS: This systematic review synthesized the perspectives of hospitalized patients regarding interprofessional collaboration and their perceived role in collaborative practices. Hospitalized patients observe interprofessional collaboration, either directly or indirectly, and the way interprofessional collaboration is performed may impact both their care and their well-being. However, little evidence has been found regarding the impact of interprofessional collaboration on patient safety. Patients' perspectives on their perceived role is not unanimous; some patients want to play an active role in the collaborative process, whereas others prefer to trust the health care professionals' expertise. Health care professionals should consider patients' preferences and act accordingly regarding both the collaborative process and the inclusion of the patients in collaborative practices.
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Pessoal de Saúde , Equipe de Assistência ao Paciente , Atenção à Saúde , Hospitalização , Humanos , Pesquisa QualitativaRESUMO
REVIEW QUESTION/OBJECTIVE: The objective of this qualitative systematic review is to examine the available evidence on interprofessional collaboration from the patients' perspectives, specifically on: i) interprofessional collaboration in adult or pediatric wards during hospitalization; ii) the influence of interprofessional collaboration on the patient's care, safety and well-being in adult or pediatric wards during hospitalization; and (iii) the patient's role in the interprofessional collaboration process in adult or pediatric wards during hospitalization.
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Comportamento Cooperativo , Hospitalização , Pacientes Internados/psicologia , Relações Interprofissionais , Equipe de Assistência ao Paciente/normas , Atitude do Pessoal de Saúde , Comunicação , Humanos , Segurança do Paciente , Assistência Centrada no Paciente , Revisões Sistemáticas como AssuntoRESUMO
OBJECTIVE: We hypothesize that radiologists' estimated percentage likelihood assessments for the presence of ductal carcinoma in situ (DCIS) and invasive cancer may predict histologic outcomes. MATERIALS AND METHODS: Two hundred fifty cases categorized as BI-RADS category 4 or 5 at four University of California Medical Centers were retrospectively reviewed by 10 academic radiologists with a range of 1-39 years in practice. Readers assigned BI-RADS category (1, 2, 3, 4a, 4b, 4c, or 5), estimated percentage likelihood of DCIS or invasive cancer (0-100%), and confidence rating (1 = low, 5 = high) after reviewing screening and diagnostic mammograms and ultrasound images. ROC curves were generated. RESULTS: Sixty-two percent (156/250) of lesions were benign and 38% (94/250) were malignant. There were 26 (10%) DCIS, 20 (8%) invasive cancers, and 48 (19%) cases of DCIS and invasive cancer. AUC values were 0.830-0.907 for invasive cancer and 0.731-0.837 for DCIS alone. Sensitivity of 82% (56/68), specificity of 84% (153/182), positive predictive value (PPV) of 66% (56/85), negative predictive value (NPV) of 93% (153/165), and accuracy of 84% ([56 + 153]/250) were calculated using an estimated percentage likelihood of 20% or higher as the prediction threshold for invasive cancer for the radiologist with the highest AUC (0.907; 95% CI, 0.864-0.951). Every 20% increase in the estimated percentage likelihood of invasive cancer increased the odds of invasive cancer by approximately two times (odds ratio, 2.4). For DCIS, using a threshold of 40% or higher, sensitivity of 81% (21/26), specificity of 79% (178/224), PPV of 31% (21/67), NPV of 97% (178/183), and accuracy of 80% ([21 + 178]/250) were calculated. Similarly, these values were calculated at thresholds of 2% or higher (BI-RADS category 4) and 95% or higher (BI-RADS category 5) to predict the presence of malignancy. CONCLUSION: Using likelihood estimates, radiologists may predict the presence of invasive cancer with fairly high accuracy. Radiologist-assigned estimated percentage likelihood can predict the presence of DCIS, albeit with lower accuracy than that for invasive cancer.
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Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/diagnóstico por imagem , Carcinoma Ductal de Mama/patologia , Competência Clínica/estatística & dados numéricos , Radiologistas/estatística & dados numéricos , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/epidemiologia , California/epidemiologia , Feminino , Humanos , Pessoa de Meia-Idade , Invasividade Neoplásica , Variações Dependentes do Observador , Prevalência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
RATIONALE AND OBJECTIVES: The study aimed to determine the inter-observer agreement among academic breast radiologists when using the Breast Imaging Reporting and Data System (BI-RADS) lesion descriptors for suspicious findings on diagnostic mammography. MATERIALS AND METHODS: Ten experienced academic breast radiologists across five medical centers independently reviewed 250 de-identified diagnostic mammographic cases that were previously assessed as BI-RADS 4 or 5 with subsequent pathologic diagnosis by percutaneous or surgical biopsy. Each radiologist assessed the presence of the following suspicious mammographic findings: mass, asymmetry (one view), focal asymmetry (two views), architectural distortion, and calcifications. For any identified calcifications, the radiologist also described the morphology and distribution. Inter-observer agreement was determined with Fleiss kappa statistic. Agreement was also calculated by years of experience. RESULTS: Of the 250 lesions, 156 (62%) were benign and 94 (38%) were malignant. Agreement among the 10 readers was strongest for recognizing the presence of calcifications (k = 0.82). There was substantial agreement among the readers for the identification of a mass (k = 0.67), whereas agreement was fair for the presence of a focal asymmetry (k = 0.21) or architectural distortion (k = 0.28). Agreement for asymmetries (one view) was slight (k = 0.09). Among the categories of calcification morphology and distribution, reader agreement was moderate (k = 0.51 and k = 0.60, respectively). Readers with more experience (10 or more years in clinical practice) did not demonstrate higher levels of agreement compared to those with less experience. CONCLUSIONS: Strength of agreement varies widely for different types of mammographic findings, even among dedicated academic breast radiologists. More subtle findings such as asymmetries and architectural distortion demonstrated the weakest agreement. Studies that seek to evaluate the predictive value of certain mammographic features for malignancy should take into consideration the inherent interpretive variability for these findings.
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Neoplasias da Mama/patologia , Mama/patologia , Calcinose/patologia , Carcinoma Ductal de Mama/patologia , Mamografia/normas , Radiologistas/normas , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Neoplasias da Mama/diagnóstico por imagem , Calcinose/diagnóstico por imagem , Carcinoma Ductal de Mama/diagnóstico por imagem , Competência Clínica/normas , Feminino , Instalações de Saúde , Humanos , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos RetrospectivosRESUMO
The American Holistic Nurses Credentialing Corporation (AHNCC), certifying body for nurses practicing within the precepts of holistic nursing, uses a systematic process to guide program development. A previous publication described their early work that distinguished basic and advanced holistic nursing and development of related examinations. A more recent publication described the work of AHNCC from 2004 to 2012, including a role-delineation study (RDS) that was undertaken to identify and validate competencies currently used by holistic nurses. A final report describes the RDS design, methods, and raw data information. This article discusses AHNCC's goals for undertaking the 2012 Holistic Nursing RDS and the implications for the certification programs.
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Certificação/normas , Competência Clínica/normas , Enfermagem Holística/normas , Licenciamento em Enfermagem/normas , Papel do Profissional de Enfermagem , Sociedades de Enfermagem/normas , American Nurses' Association/organização & administração , Saúde Holística , Humanos , Autonomia Profissional , Estados UnidosRESUMO
The toxicity and anti-diabetic properties of an aqueous plant extract made by boiling Rauwolfia vomitoria foilage and Citrus aurantium fruits were evaluated in mice. A single dosage corresponding to 70x the human-daily-dose was non-toxic when administered to 6-week-old NMRI lean mice or 6- or 11-week-old C57BL/6J lean mice. Daily treatment of 11-week-old C57BL/KsBom-db (db/db) genetic diabetic mice with a dose corresponding to 10x human-daily-dose for 6 weeks facilitated a significant weight loss as compared to the untreated controls. During treatment, the db/db mice were maintained on the carbohydrate-deficient Altromin C1009 diet. Although the food intake in the treated mice was not statistically significant from that in the controls, the treated animals had significantly higher serum triglyceride contents, suggesting that the treatment induced lipid mobilization from internal stores. Moreover, the fatty acid profile of the eyes from the treated animals showed a significant reduction in total fatty acid content accompanied by a 33% reduction in estimated Stearoyl-CoA desaturase activity (p = 0.039) as compared with controls. The fatty acid mobilization and a protection of the brittle C57BL/KsBom-db pancreas were observed 5 weeks after cessation of treatment when the treated animals were maintained on the poorer Altromin C1009 diet.
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Citrus , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/toxicidade , Hipoglicemiantes/uso terapêutico , Rauwolfia , Animais , Glicemia/análise , Peso Corporal , Modelos Animais de Doenças , Ingestão de Alimentos/efeitos dos fármacos , Frutas , Metabolismo dos Lipídeos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Nigéria , Fitoterapia , Extratos Vegetais/uso terapêutico , Folhas de Planta , Triglicerídeos/sangueRESUMO
Searching for a link between inflammation and colon cancer, we have found that the inflammatory mediator leukotriene D(4) (LTD(4)), via its receptor CysLT(1), induces cyclooxygenase-2 expression, survival, and proliferation in intestinal epithelial cells. In conjunction with our previous observation that CysLT(1) receptor expression is increased in colorectal adenocarcinomas, we here found an increased nuclear localization of the CysLT(1) receptor in colorectal adenocarcinomas. This novel discovery of CysLT(1) receptors in the nucleus was further analyzed. It was found to be located in the outer nuclear membrane in colon cancer cells and in the nontransformed epithelial cell line Int 407 cells by Western blot and electron microscopy. Cancer cells displayed higher amounts of the nuclear CysLT(1) receptor, but prolonged LTD(4) exposure induced its nuclear translocation in nontransformed cells. Truncation of a nuclear localization sequence abrogated this translocation as well as the LTD(4)-induced proliferative response. In accordance, nuclear CysLT(1) receptors exhibited proliferative extracellular signal-regulated kinase 1/2 signaling. The significance of these experimental findings is supported by the observed correlation between the proliferative marker Ki-67 and nuclear CysLT(1) receptor localization in colorectal adenocarcinomas. The present findings indicate that LTD(4) cannot only be synthesized but also signal proliferation through nuclear CysLT(1) receptors, stressing the importance of leukotrienes in inflammation-induced colon carcinogenesis.
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Adenocarcinoma/metabolismo , Neoplasias Colorretais/metabolismo , Proteínas de Membrana/metabolismo , Sinais de Localização Nuclear/metabolismo , Receptores de Leucotrienos/metabolismo , Adenocarcinoma/enzimologia , Adenocarcinoma/genética , Sequência de Aminoácidos , Araquidonato 5-Lipoxigenase/metabolismo , Células CACO-2 , Linhagem Celular Tumoral , Membrana Celular/enzimologia , Membrana Celular/metabolismo , Núcleo Celular/enzimologia , Núcleo Celular/metabolismo , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/genética , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Regulação Neoplásica da Expressão Gênica , Humanos , Leucotrieno D4/farmacologia , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Dados de Sequência Molecular , Receptores de Leucotrienos/biossíntese , Receptores de Leucotrienos/genética , Regulação para CimaRESUMO
BACKGROUND & AIMS: The effects of leukotriene (LT) D(4) on intestinal epithelial cells govern events that are involved in cell survival and colon cancer, notably increased expression of cyclooxygenase (COX)-2 and enhanced production of prostaglandin E(2). We investigated possible correlations between distribution of the recently described LTD(4) receptor CysLT(1)R and factors previously shown to be up-regulated by LTD(4) as well as clinicopathologic traits. METHODS: Immunohistochemistry and in situ hybridization were performed on tissue arrays, which were made using colorectal cancer samples from 84 patients. RESULTS: CysLT(1)R was significantly correlated to COX-2, 5-lipoxygenase, and Bcl-x(L). Male subjects more often exhibited high levels of this receptor relative to female subjects, and Dukes' B patients with elevated CysLT(1)R expression showed markedly poorer survival than those with low-level expression. Furthermore, this was paralleled by an increased viability of CysLT(1)R-overexpressing cells in a colon cancer cell line. CONCLUSIONS: Our results further implicate the involvement of LTs in colorectal carcinoma. Based on our present and earlier findings, we propose that LT/CysLT(1)R signaling facilitates survival of colon cancer cells, which may affect disease outcome. Like COX-2, LTs are accessible targets for pharmacologic treatment.
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Adenocarcinoma/metabolismo , Neoplasias Colorretais/metabolismo , Isoenzimas/metabolismo , Proteínas de Membrana , Prostaglandina-Endoperóxido Sintases/metabolismo , Receptores de Leucotrienos/metabolismo , Adenocarcinoma/patologia , Idoso , Idoso de 80 Anos ou mais , Sobrevivência Celular/fisiologia , Neoplasias Colorretais/patologia , Ciclo-Oxigenase 2 , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Análise de Sobrevida , Células Tumorais CultivadasRESUMO
The expression of chromosomal AmpC beta-lactamase in Pseudomonas aeruginosa is negatively regulated by the activity of an amidase, AmpD. In the present study we examined resistant clinical P. aeruginosa strains and several resistant variants isolated from in vivo and in vitro biofilms for mutations in ampD to find evidence for the genetic changes leading to high-level expression of chromosomal beta-lactamase. A new insertion sequence, IS1669, was found located in the ampD genes of two clinical P. aeruginosa isolates and several biofilm-isolated variants. The presence of IS1669 in ampD resulted in the expression of high levels of AmpC beta-lactamase. Complementation of these isolates with ampD from the reference P. aeruginosa strain PAO1 caused a dramatic decrease in the expression of AmpC beta-lactamase and a parallel decrease of the MIC of ceftazidime to a level comparable to that of PAO1. One highly resistant, constitutive beta-lactamase-producing variant contained no mutations in ampD, but a point mutation was observed in ampR, resulting in an Asp-135-->Asn change. An identical mutation of AmpR in Enterobacter cloacae has been reported to cause a 450-fold higher AmpC expression. However, in many of the isolates expressing high levels of chromosomal beta-lactamase, no changes were found in either ampD, ampR, or in the promoter region of ampD, ampR, or ampC. Our results suggest that multiple pathways may exist leading to increased antimicrobial resistance due to chromosomal beta-lactamase.
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Proteínas de Bactérias/genética , Cromossomos/enzimologia , Elementos de DNA Transponíveis/genética , Regulação Bacteriana da Expressão Gênica/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , N-Acetil-Muramil-L-Alanina Amidase/genética , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/genética , beta-Lactamases/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Fibrose Cística/microbiologia , Teste de Complementação Genética , Humanos , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Plasmídeos/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transformação BacterianaRESUMO
The leading cause of mortality in patients with cystic fibrosis (CF) is respiratory failure due in large part to chronic lung infection with Pseudomonas aeruginosa strains that undergo mucoid conversion, display a biofilm mode of growth in vivo and resist the infiltration of polymorphonuclear leukocytes (PMNs), which release free oxygen radicals such as H2O2. The mucoid phenotype among the strains infecting CF patients indicates overproduction of a linear polysaccharide called alginate. To mimic the inflammatory environment of the CF lung, P. aeruginosa PAO1, a typical non-mucoid strain, was grown in a biofilm. This was treated with low levels of H2O2, as if released by the PMNs, and the formation of mucoid variants was observed. These mucoid variants had mutations in mucA, which encodes an anti-sigma factor; this leads to the deregulation of an alternative sigma factor (sigma22, AlgT or AlgU) required for expression of the alginate biosynthetic operon. All of the mucoid variants tested showed the same mutation, the mucA22 allele, a common allele seen in CF isolates. The mucoid mucA22 variants, when compared to the smooth parent strain PA01, (i) produced 2-6-fold higher levels of alginate, (ii) exhibited no detectable differences in growth rate, (iii) showed an unaltered LPS profile, (iv) were approximately 72% reduced in the amount of inducible-beta-lactamase and (v) secreted little or no LasA protease and only showed 44% elastase activity. A characteristic approximately 54 kDa protein associated with alginate overproducing strains was identified as AlgE (Alg76) by N-terminal sequence analysis. Thus, the common phenotype of the mucoid variants, which included a genetically engineered mucA22 mutant, suggested that the only mutation incurred as a result of H2O2 treatment was in mucA. When a P. aeruginosa biofilm was repeatedly exposed to activated PMNs in vitro, mucoid variants were also observed, mimicking in vivo observations. Thus, PMNs and their oxygen by-products may cause P. aeruginosa to undergo the typical adaptation to the intractable mu- coid form in the CF lung. These findings indicate that gene activation in bacteria by toxic oxygen radicals, similar to that found in plants and mammalian cells, may serve as a defence mechanism for the bacteria. This suggests that mucoid conversion is a response to oxygen radical exposure and that this response is a mechanism of defence by the bacteria. This is the first report to show that PMNs and their oxygen radicals can cause this phenotypic and genotypic change which is so typical of the intractable form of P. aeruginosa in the CF lung. These findings may provide a basis for the development of anti-oxidant and anti-inflammatory therapy for the early stages of infection in CF patients.