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1.
BMC Med Educ ; 24(1): 306, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38504255

RESUMO

BACKGROUND: To fully implement the internationally acknowledged requirements for teaching in evidence-based practice, and support the student's development of core competencies in evidence-based practice, educators at professional bachelor degree programs in healthcare need a systematic overview of evidence-based teaching and learning interventions. The purpose of this overview of systematic reviews was to summarize and synthesize the current evidence from systematic reviews on educational interventions being used by educators to teach evidence-based practice to professional bachelor-degree healthcare students and to identify the evidence-based practice-related learning outcomes used. METHODS: An overview of systematic reviews. Four databases (PubMed/Medline, CINAHL, ERIC and the Cochrane library) were searched from May 2013 to January 25th, 2024. Additional sources were checked for unpublished or ongoing systematic reviews. Eligibility criteria included systematic reviews of studies among undergraduate nursing, physiotherapist, occupational therapist, midwife, nutrition and health, and biomedical laboratory science students, evaluating educational interventions aimed at teaching evidence-based practice in classroom or clinical practice setting, or a combination. Two authors independently performed initial eligibility screening of title/abstracts. Four authors independently performed full-text screening and assessed the quality of selected systematic reviews using standardized instruments. Data was extracted and synthesized using a narrative approach. RESULTS: A total of 524 references were retrieved, and 6 systematic reviews (with a total of 39 primary studies) were included. Overlap between the systematic reviews was minimal. All the systematic reviews were of low methodological quality. Synthesis and analysis revealed a variety of teaching modalities and approaches. The outcomes were to some extent assessed in accordance with the Sicily group`s categories; "skills", "attitude" and "knowledge". Whereas "behaviors", "reaction to educational experience", "self-efficacy" and "benefits for the patient" were rarely used. CONCLUSIONS: Teaching evidence-based practice is widely used in undergraduate healthcare students and a variety of interventions are used and recognized. Not all categories of outcomes suggested by the Sicily group are used to evaluate outcomes of evidence-based practice teaching. There is a need for studies measuring the effect on outcomes in all the Sicily group categories, to enhance sustainability and transition of evidence-based practice competencies to the context of healthcare practice.


Assuntos
Bacharelado em Enfermagem , Estudantes de Enfermagem , Humanos , Revisões Sistemáticas como Assunto , Prática Clínica Baseada em Evidências/educação , Atenção à Saúde , Avaliação de Resultados em Cuidados de Saúde
2.
Vaccine ; 42(7): 1582-1592, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38336558

RESUMO

Clostridioides difficile infection (CDI) is a serious healthcare-associated disease, causing symptoms such as diarrhea and pseudomembranous colitis. The major virulence factors responsible for the disease symptoms are two secreted cytotoxic proteins, TcdA and TcdB. A parenteral vaccine based on formaldehyde-inactivated TcdA and TcdB supplemented with alum adjuvant, has previously been investigated in humans but resulted in an insufficient immune response. In search for an improved response, we investigated a novel toxin inactivation method and a novel, potent adjuvant. Inactivation of toxins by metal-catalyzed oxidation (MCO) was previously shown to preserve neutralizing epitopes and to annihilate reversion to toxicity. The immunogenicity and safety of TcdA and TcdB inactivated by MCO and combined with a novel carbohydrate fatty acid monosulphate ester-based (CMS) adjuvant were investigated in rabbits. Two or three intramuscular immunizations generated high serum IgG and neutralizing antibody titers against both toxins. The CMS adjuvant increased antibody responses to both toxins while an alum adjuvant control was effective only against TcdA. Systemic safety was evaluated by monitoring body weight, body temperature, and analysis of red and white blood cell counts shortly after immunization. Local safety was assessed by histopathologic examination of the injection site at the end of the study. Body weight gain was constant in all groups. Body temperature increased up to 1 ˚C one day after the first immunization but less after the second or third immunization. White blood cell counts, and percentage of neutrophils increased one day after immunization with CMS-adjuvanted vaccines, but not with alum. Histopathology of the injection sites 42 days after the last injection did not reveal any abnormal tissue reactions. From this study, we conclude that TcdA and TcdB inactivated by MCO and combined with CMS adjuvant demonstrated promising immunogenicity and safety in rabbits and could be a candidate for a vaccine against CDI.


Assuntos
Compostos de Alúmen , Toxinas Bacterianas , Compostos de Boro , Cefalosporinas , Clostridioides difficile , Infecções por Clostridium , Animais , Coelhos , Adjuvantes Imunológicos , Proteínas de Bactérias , Vacinas Bacterianas/efeitos adversos , Peso Corporal , Infecções por Clostridium/prevenção & controle , Enterotoxinas , Toxoides
3.
Nurse Educ Today ; 133: 106082, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38141368

RESUMO

BACKGROUND: Evidence-Based Practice is recognized as a standard practice and a core competence for clinical healthcare professionals and therefore educators' competences in teaching Evidence-Based Practice are essential. Yet only little is known about the knowledge, skills, attitudes, and teaching practices around Evidence-Based Practice among educators of Danish undergraduate healthcare students. OBJECTIVES: The objectives of this study were to describe: 1) the Evidence-Based Practice profiles regarding attitudes, knowledge, skills, and teaching practices among educators who teach in undergraduate healthcare educations; 2) the current state of teaching Evidence-Based Practice in undergraduate program curricula; 3) the perceived barriers and facilitators to teach Evidence-Based Practice; and 4) the educators` needs regarding teaching Evidence-Based Practice. DESIGN, SETTING AND PARTICIPANTS: A cross-sectional survey using a self-administrated online questionnaire among 81 educators at University College South Denmark. METHODS: The survey covered 1) Demographic questions, 2) Educators Evidence-Based Practice profiles measured by the Evidence-Based Practice Questionnaire for teachers, 3) perceived state of Evidence-Based Practice teaching 4) perceived barriers and facilitators and 5) educators´ needs for competence development regarding teaching Evidence-Based Practice. RESULTS: The translated version of the Evidence-Based Practice Questionnaire showed that respondents had a mean of 3,6 regarding practicing Evidence-Based Practice when asked to rank on a scale of 1-7 (higher score indicating higher degree). The respondents showed positive attitudes towards Evidence-Based Practice and had a high self-perception of their Evidence-Based Practice skills and knowledge, scoring an overall average value of 5 on these items. In open ended questions educators gave a variety of examples of their Evidence-Based Practice teaching in terms of content, teaching methods and cooperation with clinical practice. CONCLUSIONS: Educators report limitations to teaching Evidence-Based Practice; however, attitudes, knowledge and skills were perceived generally high. Main facilitator was partnership with clinical practice and main barrier was time lack. MESH: Evidence-Based Practice, Health Educators, Knowledge, Attitude.


Assuntos
Prática Clínica Baseada em Evidências , Estudantes de Enfermagem , Humanos , Estudos Transversais , Prática Clínica Baseada em Evidências/educação , Atenção à Saúde , Inquéritos e Questionários , Dinamarca , Conhecimentos, Atitudes e Prática em Saúde , Ensino
4.
EMBO Rep ; 23(1): e53597, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34817920

RESUMO

Clostridioides difficile infections have emerged as the leading cause of healthcare-associated infectious diarrhea. Disease symptoms are mainly caused by the virulence factors, TcdA and TcdB, which are large homologous multidomain proteins. Here, we report a 2.8 Å resolution cryo-EM structure of native TcdA, unveiling its conformation at neutral pH. The structure uncovers the dynamic movement of the CROPs domain which is induced in response to environmental acidification. Furthermore, the structure reveals detailed information about the interaction area between the CROPs domain and the tip of the delivery and receptor-binding domain, which likely serves to shield the C-terminal part of the hydrophobic pore-forming region from solvent exposure. Similarly, extensive interactions between the globular subdomain and the N-terminal part of the pore-forming region suggest that the globular subdomain shields the upper part of the pore-forming region from exposure to the surrounding solvent. Hence, the TcdA structure provides insights into the mechanism of preventing premature unfolding of the pore-forming region at neutral pH, as well as the pH-induced inter-domain dynamics.


Assuntos
Toxinas Bacterianas , Clostridioides difficile , Proteínas de Bactérias/metabolismo , Toxinas Bacterianas/metabolismo , Clostridioides , Enterotoxinas/química , Enterotoxinas/metabolismo
5.
Antibiotics (Basel) ; 10(5)2021 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-33922419

RESUMO

Isavuconazole (ISZ) is used in the treatment of aspergillosis and mucormycosis. The purpose of this study was to evaluate the therapeutic drug monitoring (TDM) of ISZ samples from a clinical setting performed at Statens Serum Institut. Materials/methods: Isavuconazole serum concentrations were determined by fluorescent detection on a UHPLC. Serum-ISZ (s-ISZ) results were included and compared to those of serum-voriconazole (s-VRZ) in a 33 month period from March 2017. Clinical data were obtained for patients receiving ISZ. The therapeutic range was initially 2-10 mg/L, but was adjusted to 2-5 mg/L during the study period except for selected patients with Mucorales infections who received off-label doses of ISZ. Results: A total of 273 s-ISZ and 1242 s-VRZ measurements from 35 and 283 patients, respectively, were included. Seventeen patients had received both ISZ and VRZ with TDM within the study period. The median s-ISZ was 4.3 mg/L (0.5-15.4 mg/L) with 83% of measurements within the therapeutic index. The median s-VRZ was 2.6 mg/L (0.2-21.9 mg/L) with 67% of measurements within the therapeutic index. The median intra-/interindividual coefficient of variation (CV) was 43.4%/54.8% for ISZ compared to 53.2%/83.3% for VRZ. For patients receiving ISZ, the adverse events were mostly gastroenteric and few drug-drug interactions were observed. Furthermore, immediate change from ISZ to VRZ treatment seemed to lead to prolonged metabolism of ISZ with detection up to 35 days after discontinuation. Conclusions: The majority of patients achieved s-ISZ levels well within the therapeutic range with less intra/interindividual CV than patients receiving VRZ.

6.
Toxins (Basel) ; 13(4)2021 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-33801738

RESUMO

In the attempt to improve the purification yield of native toxin A (TcdA) and toxin B (TcdB) from Clostridioides difficile (C. difficile), we systematically evaluated culture parameters for their influence on toxin production. In this study, we showed that culturing C. difficile in a tryptone-yeast extract medium buffered in PBS (pH 7.5) that contained 5 mM ZnCl2 and 10 mM glucose supported the highest TcdB production, measured by the sandwich ELISA. These culture conditions were scalable into 5 L and 15 L dialysis tube cultures, and we were able to reach a TcdB concentration of 29.5 µg/mL of culture. Furthermore, we established a purification protocol for TcdA and TcdB using FPLC column chromatography, reaching purities of >99% for both toxins with a yield around 25% relative to the starting material. Finally, by screening the melting temperatures of TcdA and TcdB in various buffer conditions using differential scanning fluorimetry, we found optimal conditions for improving the protein stability during storage. The results of this study present a complete protocol for obtaining high amounts of highly purified native TcdA and TcdB from C. difficile.


Assuntos
Proteínas de Bactérias/isolamento & purificação , Toxinas Bacterianas/isolamento & purificação , Técnicas Bacteriológicas , Clostridioides difficile/metabolismo , Enterotoxinas/isolamento & purificação , Soluções Tampão , Cromatografia por Troca Iônica , Clostridioides difficile/crescimento & desenvolvimento , Clostridioides difficile/patogenicidade , Meios de Cultura/metabolismo , Concentração de Íons de Hidrogênio , Estabilidade Proteica
7.
Free Radic Biol Med ; 160: 433-446, 2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-32860983

RESUMO

Clostridioides difficile infections (CDI) has emerged worldwide as a serious antimicrobial-resistant healthcare-associated disease resulting in diarrhea and pseudomembranous colitis. The two cytotoxic proteins, toxin A (TcdA) and toxin B (TcdB) are the major virulence factor responsible for the disease symptoms. We examined time-dependent oxidative detoxification of TcdA and TcdB using different molar ratios of protein:Cu2+:H2O2. The metal-catalyzed oxidation (MCO) reaction in molar ratios of 1:60:1000 for protein:Cu2+:H2O2 at pH 4.5 resulted in a significant 6 log10 fold reduction in cytotoxicity after 120-min incubation at 37 °C. Circular dichroism revealed that MCO-detoxified TcdA and TcdB had secondary and tertiary structural folds similar to the native proteins. The conservation of immunogenic epitopes of both proteins was tested using monoclonal antibodies in an ELISA, comparing our MCO-detoxification approach to a conventional formaldehyde-detoxification method. The oxidative detoxification of TcdA and TcdB led to an average 2-fold reduction in antibody binding relative to native proteins, whereas formaldehyde cross-linking resulted in 3-fold and 5-fold reductions, respectively. Finally, we show that mice immunized with a vaccine consisting of MCO-detoxified TcdA and TcdB were fully protected against disease symptoms and death following a C. difficile infection and elicited substantial serum IgG responses against both TcdA and TcdB. The results of this study present copper ion-catalyzed oxidative detoxification of toxic proteins as a method highly suitable for the rapid production of safe, immunogenic and irreversible toxoid antigens for future vaccine development and may have the potential for replacing cross-linking reagents like formaldehyde.


Assuntos
Toxinas Bacterianas , Clostridioides difficile , Animais , Proteínas de Bactérias , Catálise , Clostridioides , Cobre , Enterotoxinas , Peróxido de Hidrogênio , Camundongos , Toxoides
8.
Artigo em Inglês | MEDLINE | ID: mdl-31383665

RESUMO

In recent years, cases involving terbinafine-resistant Trichophyton isolates have been reported increasingly, particularly in India. We present 14 cases of terbinafine treatment failure in Trichophyton-infected Danish patients due to acquired resistance. Patients infected with Trichophyton rubrum (n = 12) or Trichophyton interdigitale (n = 2) with elevated terbinafine MICs during 2013-2018 were included. Antifungal susceptibility testing (AFST) was performed following a modified EUCAST E.Def 9.3.1 method (5 days of incubation) with or without cycloheximide and chloramphenicol (CC) supplementation of the growth medium. The squalene epoxidase (SE) target gene was sequenced, and 3-dimensional enzyme homology modeling was performed. Most patients (12/14 [86%]) were male. The mean age was 53.5 years (range, 11 to 77 years). The mean duration of infections was 4.8 years at the time of resistance detection. Prior systemic terbinafine treatment was documented for all patients, and topical therapy for 62% (information was missing in one case). Overall, nine isolates (64%) displayed high terbinafine resistance (MICs, 4 to >8 mg/liter), while two (14%) displayed moderate (MICs, 1 to 2 mg/liter) and three (21%) displayed low (MICs, 0.125 to 0.25 mg/liter) terbinafine resistance compared with control isolates. MICs generated with or without CC supplementation were similar, but CC prevented contamination. Known and novel SE amino acid substitutions (F397L, L393F, L393S, F415S, H440Y F484Y, and I121M V237I) were detected in resistant but not control isolates. Three-dimensional homology modeling suggested a role of the novel I121M and V237I alterations. Terbinafine resistance has been detected in Denmark using a modified EUCAST method, which facilitated susceptibility testing of dermatophytes. Action is needed for this emerging public health problem.


Assuntos
Antifúngicos/farmacologia , Terbinafina/farmacologia , Trichophyton/efeitos dos fármacos , Trichophyton/patogenicidade , Adolescente , Adulto , Idoso , Antifúngicos/uso terapêutico , Criança , Farmacorresistência Fúngica/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Mutação/genética , Esqualeno Mono-Oxigenase/genética , Esqualeno Mono-Oxigenase/metabolismo , Terbinafina/uso terapêutico , Trichophyton/enzimologia , Adulto Jovem
9.
BMC Musculoskelet Disord ; 18(1): 548, 2017 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-29282073

RESUMO

BACKGROUND: Responsiveness of a clinical test is highly relevant in order to evaluate the effect of a given intervention. However, the responsiveness of clinical tests for people with neck pain has not been adequately evaluated. The objective of the present study was to examine the responsiveness of four clinical tests which are low cost and easy to perform in a clinical setting, including the craniocervical flexion test, cervical active range of movement, test for the cervical extensors and pressure pain threshold testing. METHODS: This study is a secondary analysis of data collected in a previously published randomised controlled trial. Participants were randomized to either physical training, exercises and pain education combined or pain education only. Participants were tested on the clinical tests at baseline and at 4-month follow-up. An anchor-based approach using Receiver Operator Characteristics (ROC) curves was used to evaluate responsiveness of the clinical tests. The Neck Disability Index was used to discriminate between those who had improved and those who were unchanged at the 4-month follow-up. Minimum Clinically Important Difference (MCID), together with sensitivity, specificity, positive and negative predictive values, in addition to positive and negative likelihood ratios were calculated. RESULTS: In total, 164 participants completed the 4 month follow up. One-hundred forty four participants were classified as unchanged whereas 20 patients were considered to be improved. Twenty-six participants didn't complete all of the clinical tests, leaving a total of 138 to be included for analyses. Area Under Curve (AUC) ranged from 0.50-0.62 for the clinical tests, and were all below an acceptable level. MCID was generally large, and the corresponding sensitivity and specificity was low with sensitivity ranging from 20 to 60%, and specificity from 54 to 86%. LR+ (0.8-2.07) and LR- (0.7-1.1) showed low diagnostic value for all variables, with PPV ranging from 12.1 to 26.1 and NPV ranging from 84.7 to 89.2. CONCLUSION: Responsiveness of the included clinical tests was generally low when using change in NDI score as the anchor from baseline to the 4-month follow up. Further investigations of responsiveness are warranted, possibly using other anchors, which to a higher degree resemble similar dimensions as the clinical tests.


Assuntos
Cervicalgia/diagnóstico , Medição da Dor/métodos , Educação de Pacientes como Assunto/métodos , Inquéritos e Questionários , Adulto , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Cervicalgia/terapia , Medição da Dor/normas , Educação de Pacientes como Assunto/normas , Inquéritos e Questionários/normas
10.
mSphere ; 2(3)2017.
Artigo em Inglês | MEDLINE | ID: mdl-28497121

RESUMO

Isavuconazole (ISZ) is a newly available broad-spectrum triazole agent recently approved for the treatment of both invasive aspergillosis and mucormycosis. The aim of this study was to develop a simple and reliable method for therapeutic drug monitoring (TDM) of ISZ in human plasma samples. The method involves using a kit from ChromSystems intended for TDM of itraconazole (ITZ), posaconazole (PSZ), and voriconazole (VRZ) in serum/plasma for sample preparation and high-performance liquid chromatography, using fluorescence detection with emission and excitation wavelengths set to 261 and 366 nm, respectively. The assay was linear over the ISZ concentration range of 0.2 to 20.0 mg/liter, using a 0.1-ml sample volume. The inter- and intraday coefficients of variation were all below 3.7%, whereas the accuracies ranged from 95.0 to 106.2% and the mean extraction recovery was 91.9%. In addition, the method worked well using four different Vacutainer types, with six different healthy volunteers and under a number of relevant storage conditions. Finally, the ISZ detection could be seamlessly implemented in the TDM kit for VRZ, PSZ, and ITZ, enabling simultaneous detection of all four triazoles. This method proved to be simple, accurate, precise, and well suited for routine analysis work. It has been implemented in our laboratory for the simultaneous quantitative analysis of ISZ, VRZ, PSZ, and ITZ for TDM and pharmacokinetic research. IMPORTANCE Isavuconazole is a new broad-spectrum triazole agent recently approved for the treatment of both invasive aspergillosis and mucormycosis. Currently, there is no consensus regarding the potential need for TDM of isavuconazole, and no therapeutic window has been defined. However, at the ECIL-6 meeting in 2015, it was advised that TDM is indicated in a number of different settings. In this study, we describe a rapid and validated isocratic HPLC method for fluorescence-based detection and quantification of isavuconazole in human plasma/serum samples. The method is simple and efficient with good accuracy and precision and importantly only requires a small volume of patient plasma/serum. Furthermore, this method is highly sensitive and selective and can be detected simultaneously with the three other triazoles, itraconazole, voriconazole, and posaconazole, without the need for expensive mass spectrometry equipment.

12.
Gait Posture ; 52: 211-216, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27939651

RESUMO

INTRODUCTION: For the lower limbs, the Nintendo Wii Balance Board (NWBB) has been widely used to measure postural control. However, this has not been performed for upper limb measurements. Further, the NWBB has shown to produce more background noise with decreasing loads, which may be of concern when used for upper limb testing. The aim was to investigate reproducibility and validity of the NWBB. METHODS: A test-retest design was performed with 68 subjects completing three different prone lying, upper limb weight-bearing balance tasks on a NWBB: two-arms, eyes closed (1) one-arm, non-dominant/non-injured (2) and one-arm, dominant/injured (3). Each task was repeated three times over the course of two test sessions with a 30-min break in between. Further, the level of background noise from a NWBB was compared with a force platform through systematic loading of both boards with increasing deadweights ranging from 5 to 90kg. RESULTS: Test-retest reproducibility was high with ICCs ranging from 0.95 to 0.97 (95% CI 0.92 to 0.98). However, systematic bias and tendencies for funnel effects in the Bland Altman plots for both one-armed tests were present. The concurrent validity of the NWBB was low (CCC 0.17 (95% CI 0.12-0.22)) due to large differences between the NWBB and force platform in noise sensitivity at low deadweights (especially below 50kg). CONCLUSION: The NWBB prone lying, shoulder sensorimotor control test was highly reproducible. Though, concurrent validity of the NWBB was poor compared to a force platform. Further investigation of the impact of the background noise, especially at low loads, is needed.


Assuntos
Equilíbrio Postural , Decúbito Ventral , Ombro/fisiologia , Jogos de Vídeo , Suporte de Carga , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Extremidade Superior/fisiologia , Adulto Jovem
13.
Biochim Biophys Acta Proteins Proteom ; 1865(3): 304-311, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27939608

RESUMO

Enteroaggregative Escherichia coli (EAEC) is an emerging cause of acute and persistent diarrhea worldwide. The pathogenesis of different EAEC stains is complicated, however, the early essential step begins with attachment of EAEC to intestinal mucosa via aggregative adherence fimbriae (AAFs). Currently, five different variants have been identified, which all share a degree of similarity in the gene organization of their operons and sequences. Here, we report the solution structure of Agg5A from the AAF/V variant. While preserving the major structural features shared by all AAF members, only Agg5A possesses an inserted helix at the beginning of the donor strand, which together with altered surface electrostatics, renders the protein unable to interact with fibronectin. Hence, here we characterize the first AAF variant with a binding mode that varies from previously described AAFs.


Assuntos
Aderência Bacteriana/fisiologia , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Matriz Extracelular/metabolismo , Fímbrias Bacterianas/metabolismo , Adesinas de Escherichia coli/metabolismo , Sequência de Aminoácidos , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Fibronectinas/metabolismo , Humanos , Alinhamento de Sequência
14.
J Biol Chem ; 291(25): 13286-300, 2016 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-27076635

RESUMO

Filamentation induced by cAMP (Fic) domain proteins have been shown to catalyze the transfer of the AMP moiety from ATP onto a protein target. This type of post-translational modification was recently shown to play a crucial role in pathogenicity mediated by two bacterial virulence factors. Herein we characterize a novel Fic domain protein that we identified from the human pathogen Clostridium difficile The crystal structure shows that the protein adopts a classical all-helical Fic fold, which belongs to class II of Fic domain proteins characterized by an intrinsic N-terminal autoinhibitory α-helix. A conserved glutamate residue in the inhibitory helix motif was previously shown in other Fic domain proteins to prevent proper binding of the ATP γ-phosphate. However, here we demonstrate that both ATP binding and autoadenylylation activity of the C. difficile Fic domain protein are independent of the inhibitory motif. In support of this, the crystal structure of a mutant of this Fic protein in complex with ATP reveals that the γ-phosphate adopts a conformation unique among Fic domains that seems to override the effect of the inhibitory helix. These results provide important structural insight into the adenylylation reaction mechanism catalyzed by Fic domains. Our findings reveal the presence of a class II Fic domain protein in the human pathogen C. difficile that is not regulated by autoinhibition and challenge the current dogma that all class I-III Fic domain proteins are inhibited by the inhibitory α-helix.


Assuntos
Proteínas de Bactérias/metabolismo , Clostridioides difficile/metabolismo , AMP Cíclico/metabolismo , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Clostridioides difficile/química , Cristalografia por Raios X , Enterocolite Pseudomembranosa/microbiologia , Humanos , Modelos Moleculares , Conformação Proteica , Multimerização Proteica , Estrutura Terciária de Proteína
15.
J Biol Chem ; 291(11): 5803-5816, 2016 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-26786100

RESUMO

Attaching and effacing Escherichia coli cause diarrhea and typically produce lymphostatin (LifA), an inhibitor of mitogen-activated proliferation of lymphocytes and pro-inflammatory cytokine synthesis. A near-identical factor (Efa1) has been reported to mediate adherence of E. coli to epithelial cells. An amino-terminal region of LifA shares homology with the catalytic domain of the large clostridial toxins, which are retaining glycosyltransferases with a DXD motif involved in binding of a metal ion. Understanding the mode(s) of action of lymphostatin has been constrained by difficulties obtaining a stably transformed plasmid expression clone. We constructed a tightly inducible clone of enteropathogenic E. coli O127:H6 lifA for affinity purification of lymphostatin. The purified protein inhibited mitogen-activated proliferation of bovine T lymphocytes in the femtomolar range. It is a monomer in solution and the molecular envelope was determined using both transmission electron microscopy and small-angle x-ray scattering. Domain architecture was further studied by limited proteolysis. The largest proteolytic fragment containing the putative glycosyltransferase domain was tested in isolation for activity against T cells, and was not sufficient for activity. Tryptophan fluorescence studies indicated thatlymphostatin binds uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) but not UDP-glucose (UDP-Glc). Substitution of the predicted DXD glycosyltransferase motif with alanine residues abolished UDP-GlcNAc binding and lymphostatin activity, although other biophysical properties were unchanged. The data indicate that lymphostatin has UDP-sugar binding potential that is critical for activity, and is a major leap toward identifying the nature and consequences of modifications of host cell factors.


Assuntos
Toxinas Bacterianas/química , Toxinas Bacterianas/imunologia , Doenças dos Bovinos/imunologia , Escherichia coli Enteropatogênica/imunologia , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/imunologia , Linfócitos T/microbiologia , Sequência de Aminoácidos , Animais , Bovinos , Doenças dos Bovinos/microbiologia , Escherichia coli Enteropatogênica/química , Infecções por Escherichia coli/imunologia , Infecções por Escherichia coli/microbiologia , Glicosiltransferases/química , Glicosiltransferases/imunologia , Humanos , Ativação Linfocitária , Modelos Moleculares , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Espalhamento a Baixo Ângulo , Alinhamento de Sequência , Linfócitos T/imunologia , Fatores de Virulência/imunologia , Difração de Raios X
16.
J Biol Chem ; 290(52): 31162-72, 2015 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-26527682

RESUMO

Two closely related glycosyltransferases are responsible for the final step of the biosynthesis of ABO(H) human blood group A and B antigens. The two enzymes differ by only four amino acid residues, which determine whether the enzymes transfer GalNAc from UDP-GalNAc or Gal from UDP-Gal to the H-antigen acceptor. The enzymes belong to the class of GT-A folded enzymes, grouped as GT6 in the CAZy database, and are characterized by a single domain with a metal dependent retaining reaction mechanism. However, the exact role of the four amino acid residues in the specificity of the enzymes is still unresolved. In this study, we report the first structural information of a dual specificity cis-AB blood group glycosyltransferase in complex with a synthetic UDP-GalNAc derivative. Interestingly, the GalNAc moiety adopts an unusual yet catalytically productive conformation in the binding pocket, which is different from the "tucked under" conformation previously observed for the UDP-Gal donor. In addition, we show that this UDP-GalNAc derivative in complex with the H-antigen acceptor provokes the same unusual binding pocket closure as seen for the corresponding UDP-Gal derivative. Despite this, the two derivatives show vastly different kinetic properties. Our results provide a important structural insight into the donor substrate specificity and utilization in blood group biosynthesis, which can very likely be exploited for the development of new glycosyltransferase inhibitors and probes.


Assuntos
Sistema ABO de Grupos Sanguíneos/metabolismo , Glicosiltransferases/metabolismo , Açúcares de Uridina Difosfato/metabolismo , Sistema ABO de Grupos Sanguíneos/genética , Glicosiltransferases/genética , Humanos , Açúcares de Uridina Difosfato/genética
17.
J Antimicrob Chemother ; 70(9): 2551-5, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26017038

RESUMO

OBJECTIVES: The objective of this study was to characterize the underlying molecular mechanisms in consecutive clinical Candida albicans isolates from a single patient displaying stepwise-acquired multidrug resistance. METHODS: Nine clinical isolates (P-1 to P-9) were susceptibility tested by EUCAST EDef 7.2 and Etest. P-4, P-5, P-7, P-8 and P-9 were available for further studies. Relatedness was evaluated by MLST. Additional genes were analysed by sequencing (including FKS1, ERG11, ERG2 and TAC1) and gene expression by quantitative PCR (CDR1, CDR2 and ERG11). UV-spectrophotometry and GC-MS were used for sterol analyses. In vivo virulence was determined in the insect model Galleria mellonella and evaluated by log-rank Mantel-Cox tests. RESULTS: P-1 + P-2 were susceptible, P-3 + P-4 fluconazole resistant, P-5 pan-azole resistant, P-6 + P-7 pan-azole and echinocandin resistant and P-8 + P-9 MDR. MLST supported genetic relatedness among clinical isolates. P-4 harboured four changes in Erg11 (E266D, G307S, G450E and V488I), increased expression of ERG11 and CDR2 and a change in Tac1 (R688Q). P-5, P-7, P-8 and P-9 had an additional change in Erg11 (A61E), increased expression of CDR1, CDR2 and ERG11 (except for P-7) and a different amino acid change in Tac1 (R673L). Echinocandin-resistant isolates harboured the Fks1 S645P alteration. Polyene-resistant P-8 + P-9 lacked ergosterol and harboured a frameshift mutation in ERG2 (F105SfsX23). Virulence was attenuated (but equivalent) in the clinical isolates, but higher than in the azole- and echinocandin-resistant unrelated control strain. CONCLUSIONS: C. albicans demonstrates a diverse capacity to adapt to antifungal exposure. Potentially novel resistance-inducing mutations in TAC1, ERG11 and ERG2 require independent validation.


Assuntos
Anfotericina B/farmacologia , Antifúngicos/farmacologia , Azóis/farmacologia , Candida albicans/efeitos dos fármacos , Candidíase/tratamento farmacológico , Farmacorresistência Fúngica Múltipla , Equinocandinas/farmacologia , Idoso , Animais , Candida albicans/classificação , Candida albicans/genética , Candidíase/microbiologia , DNA Fúngico/química , DNA Fúngico/genética , Genótipo , Humanos , Lepidópteros/microbiologia , Masculino , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Mutação , Análise de Sequência de DNA , Análise de Sobrevida , Virulência
18.
Transfusion ; 55(2): 422-6, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25156869

RESUMO

BACKGROUND: Discrepancies in ABO grouping arise due to different reasons, posing a threat to patient safety. Underlying causes include mixed-field agglutination after transfusion, chimerism, fetomaternal exchange, or inheritance of unusual alleles resulting in weak A/B antigen expression. Cord blood from the infant of a group A2 B mother typed as group O, H+. Samples were investigated to elucidate this conundrum. STUDY DESIGN AND METHODS: Genomic DNA was analyzed by ABO genotyping and sequencing. Red blood cells (RBCs) were characterized by routine serology and flow cytometry. Glycosyltransferase structure was predicted with 3D-modeling software. RESULTS: The mother genotyped as ABO*A1.01/B.01, and the baby, ABO*A1.01/O.01.01. Sequencing revealed a substitution, 311T>A, in the ABO*A1-like allele, which predicts Ile104Asn. Flow cytometry demonstrated A antigen on the mother's RBCs equivalent to the A2 phenotype while no A was detectable on cord RBCs. However, blood from the 11-month-old child demonstrated markedly increased A expression, likely reflecting initiation of carbohydrate chain branching. CONCLUSION: We unraveled a novel A(weak) allele (ABO*AW.29) in a case of apparent nonmaternity. Residue 104 is far from the catalytic site and may be involved in stabilizing the glycosyltransferase by dimerization. Our data support that the group AB mother's B-transferase stabilizes the altered A-transferase by heterodimerization, exemplifying the allelic enhancement phenomenon.


Assuntos
Sistema ABO de Grupos Sanguíneos/genética , Alelos , Genótipo , Sistema ABO de Grupos Sanguíneos/sangue , Adulto , Sequência de Bases , Eritrócitos/metabolismo , Feminino , Humanos , Lactente , Dados de Sequência Molecular
19.
Respir Physiol Neurobiol ; 205: 77-83, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25448397

RESUMO

The study aimed to investigate diaphragm respiratory drive modulation through electrical activity of the diaphragm (EADi) during progressive cycling in endurance-trained men (N=7) and to test day-to-day measurement reliability. Normalized EADi increased at exercise intensities from 40% workload (WL) to 70% and 85%WL but plateaued from 70% to 85% (p<0.05). V˙O2, V˙CO2, V˙E, increased at all exercise intensities, where Vt and BF increased from 40% to 55% WL and from 70% to 85% and RER increased at 70% and 85% (p<0.05). Bland-Altman plots of normalized EADi showed bias of 0.9% and -6.4% and limits of agreement of ±36.0% and ±30.4% for absolute measurements and relative changes from 40% WL, respectively. Within-day variability appeared constant indicating that measurements within a trial are reliable. Results suggest that diaphragm respiratory drive increases at moderate exercise intensities, but plateaus at high intensities where other respiratory muscles might contribute significantly to the breathing effort, perhaps to "protect" against diaphragm fatigue.


Assuntos
Diafragma/fisiologia , Exercício Físico/fisiologia , Resistência Física/fisiologia , Fenômenos Fisiológicos Respiratórios , Adulto , Ciclismo , Feminino , Humanos , Masculino
20.
BMC Musculoskelet Disord ; 15: 408, 2014 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-25477032

RESUMO

BACKGROUND: The reliability of clinical tests for the cervical spine has not been adequately evaluated. Six cervical clinical tests, which are low cost and easy to perform in clinical settings, were tested for intra- and inter-examiner reliability, and two performance tests were assessed for test-retest reliability in people with and without chronic neck pain. Moreover, construct and between-group discriminative validity of the tests were examined. METHODS: Twenty-one participants with chronic neck pain and 21 asymptomatic participants were included. Intra- and inter-reliability were evaluated for the Cranio-Cervical Flexion Test (CCFT), Range of Movement (ROM), Joint Position Error (JPE), Gaze Stability (GS), Smooth Pursuit Neck Torsion Test (SPNTT), and neuromuscular control of the Deep Cervical Extensors (DCE). Test-retest reliability was assessed for Postural Control (SWAY) and Pressure Pain Threshold (PPT) over tibialis anterior, infraspinatus and the C3-C4 segment. RESULTS: Intraclass Correlation Coefficient (ICC) for intra- and inter-examiner reliability was highest for ROM (range: 0.80 to 0.94), DCE (0.75 to 0.90) and CCFT (0.63 to 0.86). JPE had the lowest ICC (0.02 to 0.66). Intra- and inter-reliability for GS and SPNTT showed kappa ranging from 0.66 to 0.92, and 0.57 to 0.78 (prevalence adjusted), respectively. For the test-retest study, ICC was 0.83 to 0.89 for PPT and 0.39 to 0.79 for SWAY. Construct validity was satisfactory for all tests, except JPE. Significant between group discriminative validity was found for CCFT, ROM, GS, SPNTT and PPT, however, differences were within the limits of the minimal detectable change. CONCLUSIONS: The majority of the tests evaluated showed satisfactory reliability and construct validity supporting their use in the clinical evaluation of patients with chronic neck pain.


Assuntos
Dor Crônica/diagnóstico , Cervicalgia/diagnóstico , Medição da Dor/normas , Adulto , Dor Crônica/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cervicalgia/epidemiologia , Medição da Dor/métodos , Reprodutibilidade dos Testes , Autorrelato/normas , Método Simples-Cego
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