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1.
Ann Emerg Med ; 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38795079

RESUMO

STUDY OBJECTIVE: Boarding admitted patients in emergency departments (EDs) is a national crisis that is worsening despite potential financial disadvantages. The objective of this study was to assess costs associated with boarding. METHODS: We conducted a prospective, observational investigation of patients admitted through an ED for management of acute stroke at a large, urban, academic, comprehensive stroke center hospital. We employed time-driven activity-based costing methodology to estimate cost for patient care activities during admission and aggregated results to estimate the total cost of boarding versus inpatient care. Primary outcomes were total daily costs per patient for medical-surgical (med/surg) boarding, med/surg inpatient care, ICU boarding, and ICU inpatient care. RESULTS: The total daily cost per patient with acute stroke was US$1856, for med/surg boarding versus US$993 for med/surg inpatient care and US$2267, for ICU boarding versus US$2165, for ICU inpatient care. These differences were even greater when accounting for costs associated with traveler nurses. ED nurses spent 293 min/d (mean) caring for each med/surg boarder; inpatient nurses spent 313 min/d for each med/surg inpatient. ED nurses spent 419 min/d caring for each ICU boarder; inpatient nurses spent 787 min/d for each ICU inpatient. Neurology attendings and residents spent 25 and 52 min/d caring for each med/surg boarder versus 62 minutes and 90 minutes for each med/surg inpatient, respectively. CONCLUSION: Using advanced cost-accounting methods, our investigation provides novel evidence that boarding of admitted patients is financially costly, adding greater urgency for elimination of this practice.

2.
J Emerg Med ; 66(3): e383-e390, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38278682

RESUMO

BACKGROUND: The end of 2019 marked the emergence of the COVID-19 pandemic. Public avoidance of health care facilities, including the emergency department (ED), has been noted during prior pandemics. OBJECTIVE: This study described pandemic-related changes in adult and pediatric ED presentations, acuity, and hospitalization rates during the pandemic in a major metropolitan area. METHODS: The study was a cross-sectional analysis of ED visits occurring before and during the pandemic. Sites collected daily ED patient census; monthly ED patient acuity, as the Emergency Severity Index (ESI) score; and disposition. Prepandemic ED visits occurring from January 1, 2019 through December 31, 2019 were compared with ED visits occurring during the pandemic from January 1, 2020 through March 31, 2021. The change in prepandemic and pandemic ED volume was found using 7-day moving average of proportions. RESULTS: The study enrolled 83.8% of the total ED encounters. Pandemic adult and pediatric visit volume decreased to as low as 44.7% (95% CI 43.1-46.3%; p < 0.001) and 22.1% (95% CI 19.3-26.0%; p < 0.001), respectively, of prepandemic volumes. There was also a relative increase in adult and pediatric acuity (ESI level 1-3) and the admission percentage for adult (20.3% vs. 22.9%; p < 0.01) and pediatric (5.1% vs. 5.6%; p < 0.01) populations. CONCLUSIONS: Total adult and pediatric encounters were reduced significantly across a major metropolitan area. Patient acuity and hospitalization rates were relatively increased. The development of strategies for predicting ED avoidance will be important in future pandemics.


Assuntos
COVID-19 , Adulto , Humanos , Criança , COVID-19/epidemiologia , Pandemias , Estudos Transversais , Estudos Retrospectivos , Serviço Hospitalar de Emergência
3.
Infect Immun ; 91(5): e0007923, 2023 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-37092998

RESUMO

Neisseria meningitidis historically has been an infrequent and sporadic cause of urethritis and other urogenital infections. However, a nonencapsulated meningococcal clade belonging to the hyperinvasive clonal complex 11.2 lineage has recently emerged and caused clusters of urethritis cases in the United States and other countries. One of the genetic signatures of the emerging N. meningitidis urethritis clade (NmUC) is a chromosomal gene conversion event resulting in the acquisition of the Neisseria gonorrhoeae denitrification apparatus-the N. gonorrhoeae alleles encoding the nitrite reductase AniA, the nitric oxide (NO) reductase NorB, and the intergenic promoter region. The biological importance of the N. gonorrhoeae AniA-NorB for adaptation of the NmUC to a new environmental niche is investigated herein. We found that oxygen consumption, nitrite utilization, and NO production were significantly altered by the conversion event, resulting in different denitrifying aerobic and microaerobic growth of the clade. Further, transcription of aniA and norB in NmUC isolates differed from canonical N. meningitidis, and important polymorphisms within the intergenic region, which influenced aniA promoter activity of the NmUC, were identified. The contributions of three known meningococcal regulators (NsrR, FNR, and NarQP) in controlling the denitrification pathway and endogenous NO metabolism were distinct. Overall, transcription of aniA was dampened relative to canonical N. meningitidis, and this correlated with the lower NO accumulation in the clade. Denitrification and microaerobic respiration were bolstered, and protection against host-derived NO was likely enhanced. The acquisition of the N. gonorrhoeae denitrification pathway by the NmUC supports the clade's adaptation and survival in a microaerobic urogenital environment.


Assuntos
Gonorreia , Neisseria meningitidis , Uretrite , Estados Unidos , Humanos , Neisseria meningitidis/genética , Neisseria meningitidis/metabolismo , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/metabolismo , Óxido Nítrico/metabolismo , Respiração
4.
Antimicrob Agents Chemother ; 67(1): e0096822, 2023 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-36602335

RESUMO

Neisseria gonorrhoeae has developed resistance to all previous antibiotics used for treatment. This highlights a crucial need for novel antimicrobials to treat gonococcal infections. We previously showed that carbamazepine (Cz), one of the most commonly prescribed antiepileptic drugs, can block the interaction between gonococcal pili and the I-domain region of human complement receptor 3 (CR3)-an interaction that is vital for infection of the female cervix. We also show that Cz can completely clear an established N. gonorrhoeae infection of primary human cervical cells. In this study, we quantified Cz in serum, saliva, and vaginal fluid collected from 16 women who were, or were not, regularly taking Cz. We detected Cz in lower reproductive tract mucosal secretions in the test group (women taking Cz) at potentially therapeutic levels using a competitive ELISA. Furthermore, we found that Cz concentrations present in vaginal fluid from women taking this drug were sufficient to result in a greater than 99% reduction (within 24 h) in the number of viable gonococci recovered from ex vivo, human, primary cervical cell infections. These data provide strong support for the further development of Cz as a novel, host-targeted therapy to treat gonococcal cervicitis.


Assuntos
Epilepsia , Gonorreia , Humanos , Feminino , Reposicionamento de Medicamentos , Gonorreia/tratamento farmacológico , Neisseria gonorrhoeae , Carbamazepina/uso terapêutico , Carbamazepina/farmacologia
5.
Br J Anaesth ; 131(1): 56-66, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37117099

RESUMO

BACKGROUND: Little is known about the opportunities for shared decision-making when older high-risk patients are offered major surgery. This study examines how, when, and why clinicians and patients can share decision-making about major surgery. METHODS: This was a multi-method qualitative study, combining video recordings of preoperative consultations, interviews, and focus groups (33 patients, 19 relatives, 36 clinicians), with observations and documentary analysis in clinics in five hospitals in the UK undertaking major orthopaedic, colorectal, and/or cardiac surgery. RESULTS: Three opportunities for shared decision-making about major surgery were identified. Resolution-focused consultations (cardiac/colorectal) resulted in a single agreed preferred option related to a potentially life-threatening problem, with limited opportunities for shared decision-making. Evaluative and deliberative consultations offered more opportunity. The former focused on assessing the likelihood of benefits of surgery for a presenting problem that was not a threat to life for the patient (e.g., orthopaedic consultations) and the latter (largely colorectal) involved discussion of a range of options while also considering significant comorbidities and patient preferences. The extent to which opportunities for shared decision-making were available, and taken up by surgeons, was influenced by the nature of the presenting problem, clinical pathway, and patient trajectory. CONCLUSIONS: Decisions about major surgery were not always shared between patients and doctors. The nature of the presenting problem, comorbidities, clinical pathways, and patient trajectories all informed the type of consultation and opportunities for sharing decision-making. Our findings have implications for clinicians, with shared decision-making about major surgery most feasible when the focus is on life-enhancing treatment.


Assuntos
Neoplasias Colorretais , Cirurgiões , Humanos , Tomada de Decisões , Tomada de Decisão Compartilhada , Gravação em Vídeo , Participação do Paciente , Relações Médico-Paciente
6.
Langenbecks Arch Surg ; 408(1): 378, 2023 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-37749405

RESUMO

BACKGROUND: Whilst there has been significant improvement in mortality outcomes after emergency laparotomy, there is little information on longer term outcomes in the year after discharge. The main aim of the study was to assess the impact that an emergency laparotomy has on patients' and employment and health status 1 year after surgery. METHODS: This study was a questionnaire study conducted in a single centre district general hospital of patients who had undergone an emergency laparotomy between October 2015 and December 2016. Patients were included according to the National Emergency Laparotomy Audit criteria. At screening, patients who were alive at 1 year and had the capacity to consent were approached between January and December 2017. Patients underwent a researcher-led telephone interview using a semi-structured questionnaire to assess the impact of emergency laparotomy on overall, general and physical health (Glasgow Benefit Inventory) as well as employment status. The symptoms that patients experienced and their impact were also recorded. RESULTS: Forty-two patients responded to and completed the questionnaire. Just over one-third of patients experienced a deterioration in their general or physical health and 21% of patients experienced a change in employment. Factors which significantly impacted on health status were stoma issues, postoperative morbidity and a change in employment (p < 0.05). The main symptoms which patients identified as being troublesome were altered bowel habit and stoma issues with a resultant social and psychological impact. CONCLUSIONS: One-third of patients experienced a deterioration in their psychosocial and physical health status as well as a change in employment during the first-year postsurgery. Larger research studies are required to define the impact of emergency laparotomy on patients in the longer term and more research is needed to improve perioperative rehabilitation in the postoperative period to ensure optimal functional gain after technically successful surgery.


Assuntos
Emprego , Laparotomia , Humanos , Nível de Saúde , Alta do Paciente , Medidas de Resultados Relatados pelo Paciente
7.
Antimicrob Agents Chemother ; 66(9): e0231821, 2022 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-35980187

RESUMO

Multidrug-resistant (MDR) N. gonorrhoeae is a current public health threat. New therapies are urgently needed. PBT2 is an ionophore that disrupts metal homeostasis. PBT2 administered with zinc is shown to reverse resistance to antibiotics in several bacterial pathogens. Here we show that both N. meningitidis and MDR N. gonorrhoeae are sensitive to killing by PBT2 alone. PBT2 is, thus, a candidate therapeutic for MDR N. gonorrhoeae infections.


Assuntos
Gonorreia , Neisseria meningitidis , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Gonorreia/tratamento farmacológico , Gonorreia/microbiologia , Humanos , Ionóforos/farmacologia , Ionóforos/uso terapêutico , Testes de Sensibilidade Microbiana , Neisseria gonorrhoeae , Zinco
8.
J Antimicrob Chemother ; 76(11): 2850-2853, 2021 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-34450628

RESUMO

BACKGROUND: Neisseria gonorrhoeae is a Gram-negative bacterial pathogen that causes gonorrhoea. No vaccine is available to prevent gonorrhoea and the emergence of MDR N. gonorrhoeae strains represents an immediate public health threat. OBJECTIVES: To evaluate whether PBT2/zinc may sensitize MDR N. gonorrhoeae to natural cationic antimicrobial peptides. METHODS: MDR strains that contain differing resistance mechanisms against numerous antibiotics were tested in MIC assays. MIC assays were performed using the broth microdilution method according to CLSI guidelines in a microtitre plate. Serially diluted LL-37 or PG-1 was tested in combination with a sub-inhibitory concentration of PBT2/zinc. Serially diluted tetracycline was also tested with sub-inhibitory concentrations of PBT2/zinc and LL-37. SWATH-MS proteomic analysis of N. gonorrhoeae treated with PBT2/zinc, LL-37 and/or tetracycline was performed to determine the mechanism(s) of N. gonorrhoeae susceptibility to antibiotics and peptides. RESULTS: Sub-inhibitory concentrations of LL-37 and PBT2/zinc synergized to render strain WHO-Z susceptible to tetracycline, whereas the killing effect of PG-1 and PBT2/zinc was additive. SWATH-MS proteomic analysis suggested that PBT2/zinc most likely leads to a loss of membrane integrity and increased protein misfolding and, in turn, results in bacterial death. CONCLUSIONS: Here we show that PBT2, a candidate Alzheimer's and Huntington's disease drug, can be repurposed to render MDR N. gonorrhoeae more susceptible to the endogenous antimicrobial peptides LL-37 and PG-1. In the presence of LL-37, PBT2/zinc can synergize with tetracycline to restore tetracycline susceptibility to gonococci resistant to this antibiotic.


Assuntos
Doença de Alzheimer , Gonorreia , Doença de Huntington , Preparações Farmacêuticas , Doença de Alzheimer/tratamento farmacológico , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Peptídeos Catiônicos Antimicrobianos/farmacologia , Peptídeos Antimicrobianos , Gonorreia/tratamento farmacológico , Humanos , Doença de Huntington/tratamento farmacológico , Testes de Sensibilidade Microbiana , Neisseria gonorrhoeae , Proteômica
9.
J Infect Dis ; 221(3): 449-453, 2020 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-31541571

RESUMO

L-lactate is an abundant metabolite in a number of niches in host organisms and represents an important carbon source for bacterial pathogens such as Neisseria gonorrhoeae. In this study, we describe an alternative, iron-sulfur cluster-containing L-lactate dehydrogenase (LutACB), that is distinct from the flavoprotein L-lactate dehydrogenase (LldD). Expression of lutACB was found to be positively regulated by iron, whereas lldD was more highly expressed under conditions of iron-limitation. The functional role of LutACB and LldD was reflected in in vitro studies of growth and in the survival of N gonorrhoeae in primary cervical epithelial cells.


Assuntos
Proteínas de Bactérias/metabolismo , Colo do Útero/citologia , Células Epiteliais/microbiologia , Gonorreia/metabolismo , L-Lactato Desidrogenase/metabolismo , Viabilidade Microbiana/genética , Neisseria gonorrhoeae/enzimologia , Proteínas de Bactérias/genética , Feminino , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Gonorreia/microbiologia , Humanos , Ferro/metabolismo , L-Lactato Desidrogenase/genética , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/crescimento & desenvolvimento , RNA Viral/genética
10.
Philos Trans A Math Phys Eng Sci ; 378(2176): 20200062, 2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32623987

RESUMO

The direct synthesis of hydrogen peroxide (H2O2) from molecular H2 and O2 offers an attractive, decentralized alternative to production compared to the current means of production, the anthraquinone process. Herein we evaluate the performance of a 0.5%Pd-4.5%Ni/TiO2 catalyst in batch and flow reactor systems using water as a solvent at ambient temperature. These reaction conditions are considered challenging for the synthesis of high H2O2 concentrations, with the use of sub-ambient temperatures and alcohol co-solvents typical. Catalytic activity was observed to be stable to prolonged use in multiple batch experiments or in a flow system, with selectivities towards H2O2 of 97% and 85%, respectively. This study was carried out in the absence of halide or acid additives that are typically used to inhibit sequential H2O2 degradation reactions showing that this Pd-Ni catalyst has the potential to produce H2O2 selectively. This article is part of a discussion meeting issue 'Science to enable the circular economy'.

11.
Lancet ; 401(10389): 1646-1647, 2023 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-37211015
12.
Curr Opin Infect Dis ; 31(3): 246-250, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29601324

RESUMO

PURPOSE OF REVIEW: Neisseria gonorrhoeae is one of the most common causes of sexually transmitted infections, with an estimated more than 100 million cases of gonorrhea each year worldwide. N. gonorrhoeae has gained recent increasing attention because of the alarming rise in incidence and the widespread emergence of multidrug-resistant gonococcal strains. Vaccine development is one area of renewed interest. Herein, we review the recent advances in this area. RECENT FINDINGS: Vaccine development for N. gonorrhoeae has been problematic, but recent progress in the field has provided new hope that a gonococcal vaccine may be feasible. Several new vaccine antigens have been characterized in various models of infection. Furthermore, the first potential vaccine-induced protection against gonorrhea in humans has been reported, with decreased rates of gonorrhea described among individuals vaccinated with the Neisseria meningitidis serogroup B vaccine, MeNZB. SUMMARY: As antibiotic resistance continues to increase, vaccine development for N. gonorrhoeae becomes more urgent. The MeNZB vaccine is shown to have efficacy, albeit relatively low, against N. gonorrhoeae. This finding has the potential to reinvigorate research in the field of gonococcal vaccine development and will guide future studies of the antigens and mechanism(s) required for protection against gonococcal infection.


Assuntos
Vacinas Bacterianas/imunologia , Transmissão de Doença Infecciosa/prevenção & controle , Descoberta de Drogas/tendências , Gonorreia/prevenção & controle , Vacinas Meningocócicas/imunologia , Neisseria gonorrhoeae/imunologia , Vacinas Bacterianas/isolamento & purificação , Humanos , Vacinas Meningocócicas/administração & dosagem
13.
Faraday Discuss ; 208(0): 409-425, 2018 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-29796569

RESUMO

A series of 1 wt% supported Au, Pd and AuPd nanoalloy catalysts were prepared via microwave assisted reduction of PdCl2 and HAuCl4 in a facile, one pot process. The resulting materials showed excellent activity for the direct synthesis of hydrogen peroxide from hydrogen and oxygen, with a synergistic effect observed on the addition of Au into a Pd catalyst. Detailed electron microscopy showed that the bimetallic particles exhibited a core-shell morphology, with an Au core surrounded by an Au-Pd shell, with a size between 10-20 nm. The presence of Au in the shell was confirmed by EDX studies, with corroborating data from XPS measurements showing a significant contribution of both Au and Pd in the spectra, with the Au signal increasing as the total Au content of the catalyst increased. No PdO was observed, suggesting a complete reduction of the metal chloride nanoparticles. Unlike similar catalysts prepared by sol-immobilisation methodology, the core-shell structures showed excellent stability during the hydrogen peroxide synthesis reaction, and no catalyst deactivation was observed over 4 reuse cycles. This is the first time the preparation of stable core-shell particles have been reported using microwave assisted reduction. The observation that these particles are core-shell, without the need of a complicated synthesis or high thermal treatment and form in just 15 minutes presents an exciting opportunity for this experimental technique.

14.
Philos Trans A Math Phys Eng Sci ; 376(2110)2018 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-29175960

RESUMO

A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition.This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

15.
J Biol Chem ; 291(17): 8862-75, 2016 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-26826123

RESUMO

Establishing the in vivo activation status of G protein-coupled receptors would not only indicate physiological roles of G protein-coupled receptors but would also aid drug discovery by establishing drug/receptor engagement. Here, we develop a phospho-specific antibody-based biosensor to detect activation of the M1 muscarinic acetylcholine receptor (M1 mAChR) in vitro and in vivo Mass spectrometry phosphoproteomics identified 14 sites of phosphorylation on the M1 mAChR. Phospho-specific antibodies to four of these sites established that serine at position 228 (Ser(228)) on the M1 mAChR showed extremely low levels of basal phosphorylation that were significantly up-regulated by orthosteric agonist stimulation. In addition, the M1 mAChR-positive allosteric modulator, 1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, enhanced acetylcholine-mediated phosphorylation at Ser(228) These data supported the hypothesis that phosphorylation at Ser(228) was an indicator of M1 mAChR activation. This was further supported in vivo by the identification of phosphorylated Ser(228) on the M1 mAChR in the hippocampus of mice following administration of the muscarinic ligands xanomeline and 1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid. Finally, Ser(228) phosphorylation was seen to increase in the CA1 region of the hippocampus following memory acquisition, a response that correlated closely with up-regulation of CA1 neuronal activity. Thus, determining the phosphorylation status of the M1 mAChR at Ser(228) not only provides a means of establishing receptor activation following drug treatment both in vitro and in vivo but also allows for the mapping of the activation status of the M1 mAChR in the hippocampus following memory acquisition thereby establishing a link between M1 mAChR activation and hippocampus-based memory and learning.


Assuntos
Anticorpos Monoclonais Murinos/química , Técnicas Biossensoriais/métodos , Região CA1 Hipocampal/metabolismo , Aprendizagem/fisiologia , Memória/fisiologia , Fosfoproteínas/metabolismo , Receptor Muscarínico M1/metabolismo , Animais , Região CA1 Hipocampal/citologia , Células CHO , Cricetinae , Cricetulus , Camundongos , Fosfoproteínas/genética , Fosforilação/fisiologia , Receptor Muscarínico M1/genética
16.
Crit Rev Microbiol ; 42(6): 928-41, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26805040

RESUMO

Gonorrhea is a major, global public health problem for which there is no vaccine. The continuing emergence of antibiotic-resistant strains raises concerns that untreatable Neisseria gonorrhoeae may become widespread in the near future. Consequently, there is an urgent need for increased efforts towards the development of new anti-gonococcal therapeutics and vaccines, as well as suitable models for potential pre-clinical vaccine trials. Several current issues regarding gonorrhea are discussed herein, including the global burden of disease, the emergence of antibiotic-resistance, the status of vaccine development and, in particular, a focus on the model systems available to evaluate drug and vaccine candidates. Finally, alternative approaches to evaluate vaccine candidates are presented. Such approaches may provide valuable insights into the protective mechanisms, and correlates of protection, required to prevent gonococcal transmission, local infection and disease sequelae.


Assuntos
Vacinas Bacterianas/imunologia , Gonorreia/imunologia , Gonorreia/prevenção & controle , Neisseria gonorrhoeae/imunologia , Animais , Vacinas Bacterianas/administração & dosagem , Vacinas Bacterianas/genética , Gonorreia/microbiologia , Humanos , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/patogenicidade , Virulência
18.
PLoS Pathog ; 9(5): e1003377, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23696740

RESUMO

Pili of pathogenic Neisseria are major virulence factors associated with adhesion, twitching motility, auto-aggregation, and DNA transformation. Pili of N. meningitidis are subject to several different post-translational modifications. Among these pilin modifications, the presence of phosphorylcholine (ChoP) and a glycan on the pilin protein are phase-variable (subject to high frequency, reversible on/off switching of expression). In this study we report the location of two ChoP modifications on the C-terminus of N. meningitidis pilin. We show that the surface accessibility of ChoP on pili is affected by phase variable changes to the structure of the pilin-linked glycan. We identify for the first time that the platelet activating factor receptor (PAFr) is a key, early event receptor for meningococcal adherence to human bronchial epithelial cells and tissue, and that synergy between the pilin-linked glycan and ChoP post-translational modifications is required for pili to optimally engage PAFr to mediate adherence to human airway cells.


Assuntos
Aderência Bacteriana , Membrana Celular/metabolismo , Células Epiteliais/metabolismo , Proteínas de Fímbrias/metabolismo , Fímbrias Bacterianas/metabolismo , Neisseria meningitidis/metabolismo , Processamento de Proteína Pós-Traducional , Mucosa Respiratória/metabolismo , Linhagem da Célula , Membrana Celular/microbiologia , Células Epiteliais/microbiologia , Proteínas de Fímbrias/genética , Fímbrias Bacterianas/genética , Humanos , Neisseria meningitidis/genética , Neisseria meningitidis/patogenicidade , Fosforilcolina/metabolismo , Mucosa Respiratória/microbiologia
19.
Acc Chem Res ; 47(3): 845-54, 2014 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-24175914

RESUMO

Hydrogen peroxide is a widely used chemical but is not very efficient to make in smaller than industrial scale. It is an important commodity chemical used for bleaching, disinfection, and chemical manufacture. At present, manufacturers use an indirect process in which anthraquinones are sequentially hydrogenated and oxidized in a manner that hydrogen and oxygen are never mixed. However, this process is only economic at a very large scale producing a concentrated product. For many years, the identification of a direct process has been a research goal because it could operate at the point of need, producing hydrogen peroxide at the required concentration for its applications. Research on this topic has been ongoing for about 100 years. Until the last 10 years, catalyst design was solely directed at using supported palladium nanoparticles. These catalysts require the use of bromide and acid to arrest peroxide decomposition, since palladium is a very active catalyst for hydrogen peroxide hydrogenation. Recently, chemists have shown that supported gold nanoparticles are active when gold is alloyed with palladium because this leads to a significant synergistic enhancement in activity and importantly selectivity. Crucially, bimetallic gold-based catalysts do not require the addition of bromide and acids, but with carbon dioxide as a diluent its solubility in the reaction media acts as an in situ acid promoter, which represents a greener approach for peroxide synthesis. The gold catalysts can operate under intrinsically safe conditions using dilute hydrogen and oxygen, yet these catalysts are so active that they can generate peroxide at commercially significant rates. The major problem associated with the direct synthesis of hydrogen peroxide concerns the selectivity of hydrogen usage, since in the indirect process this factor has been finely tuned over decades of operation. In this Account, we discuss how the gold-palladium bimetallic catalysts have active sites for the synthesis and hydrogenation of hydrogen peroxide that are different, in contrast to monometallic palladium in which synthesis and hydrogenation operate at the same sites. Through treatment of the support with acids prior to the deposition of the gold-palladium bimetallic particles, we can obtain a catalyst that can make hydrogen peroxide at a very high rate without decomposing or hydrogenating the product. This innovation opens up the way to design improved catalysts for the direct synthesis process, and these possibilities are described in this Account.

20.
Blood ; 121(8): 1335-44, 2013 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-23287868

RESUMO

Histone deacetylase 1 and 2 (HDAC1/2) regulate chromatin structure as the catalytic core of the Sin3A, NuRD and CoREST co-repressor complexes. To better understand the key pathways regulated by HDAC1/2 in the adaptive immune system and inform their exploitation as drug targets, we have generated mice with a T-cell specific deletion. Loss of either HDAC1 or HDAC2 alone has little effect, while dual inactivation results in a 5-fold reduction in thymocyte cellularity, accompanied by developmental arrest at the double-negative to double-positive transition. Transcriptome analysis revealed 892 misregulated genes in Hdac1/2 knock-out thymocytes, including down-regulation of LAT, Themis and Itk, key components of the T-cell receptor (TCR) signaling pathway. Down-regulation of these genes suggests a model in which HDAC1/2 deficiency results in defective propagation of TCR signaling, thus blocking development. Furthermore, mice with reduced HDAC1/2 activity (Hdac1 deleted and a single Hdac2 allele) develop a lethal pathology by 3-months of age, caused by neoplastic transformation of immature T cells in the thymus. Tumor cells become aneuploid, express increased levels of c-Myc and show elevated levels of the DNA damage marker, γH2AX. These data demonstrate a crucial role for HDAC1/2 in T-cell development and the maintenance of genomic stability.


Assuntos
Transformação Celular Neoplásica/genética , Instabilidade Genômica/genética , Histona Desacetilase 1/genética , Histona Desacetilase 2/genética , Linfócitos T/enzimologia , Animais , Animais Recém-Nascidos , Transformação Celular Neoplásica/imunologia , Cromatina/genética , Aberrações Cromossômicas , Dano ao DNA/genética , Dano ao DNA/imunologia , Ativação Enzimática/genética , Ativação Enzimática/imunologia , Feminino , Instabilidade Genômica/imunologia , Haploinsuficiência/genética , Haploinsuficiência/imunologia , Histona Desacetilase 1/metabolismo , Histona Desacetilase 2/metabolismo , Masculino , Camundongos , Camundongos Knockout , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Linfócitos T/citologia , Timo/citologia , Transcriptoma/imunologia
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