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1.
J Biol Chem ; 299(12): 105438, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37944618

RESUMO

The tachykinin receptors neurokinin 1 (NK1R) and neurokinin 2 (NK2R) are G protein-coupled receptors that bind preferentially to the natural peptide ligands substance P and neurokinin A, respectively, and have been targets for drug development. Despite sharing a common C-terminal sequence of Phe-X-Gly-Leu-Met-NH2 that helps direct biological function, the peptide ligands exhibit some degree of cross-reactivity toward each other's non-natural receptor. Here, we investigate the detailed structure-activity relationships of the ligand-bound receptor complexes that underlie both potent activation by the natural ligand and cross-reactivity. We find that the specificity and cross-reactivity of the peptide ligands can be explained by the interactions between the amino acids preceding the FxGLM consensus motif of the bound peptide ligand and two regions of the receptor: the ß-hairpin of the extracellular loop 2 (ECL2) and a N-terminal segment leading into transmembrane helix 1. Positively charged sidechains of the ECL2 (R177 of NK1R and K180 of NK2R) are seen to play a vital role in the interaction. The N-terminal positions 1 to 3 of the peptide ligand are entirely dispensable. Mutated and chimeric receptor and ligand constructs neatly swap around ligand specificity as expected, validating the structure-activity hypotheses presented. These findings will help in developing improved agonists or antagonists for NK1R and NK2R.


Assuntos
Receptores da Neurocinina-1 , Taquicininas , Animais , Humanos , Linhagem Celular , Chlorocebus aethiops , Ligantes , Neurocinina A/metabolismo , Antagonistas dos Receptores de Neurocinina-1 , Receptores da Neurocinina-1/agonistas , Receptores da Neurocinina-1/metabolismo , Substância P , Taquicininas/metabolismo , Receptores da Neurocinina-2/metabolismo
2.
Cochrane Database Syst Rev ; 3: CD000352, 2023 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-36884026

RESUMO

BACKGROUND: Observational studies of increasingly better quality and in different settings suggest that planned hospital birth in many places does not reduce mortality and morbidity but increases the frequency of interventions and complications. Euro-Peristat (part of the European Union's Health Monitoring Programme) has raised concerns about iatrogenic effects of obstetric interventions, and the World Health Organization (WHO) has raised concern that the increasing medicalisation of childbirth tends to undermine women's own capability to give birth and negatively impacts their childbirth experience. This is an update of a Cochrane Review first published in 1998, and previously updated in 2012. OBJECTIVES: To compare the effects of planned hospital birth with planned home birth attended by a midwife or others with midwifery skills and backed up by a modern hospital system in case a transfer to hospital should turn out to be necessary. The primary focus is on women with an uncomplicated pregnancy and low risk of medical intervention during birth.  SEARCH METHODS: For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register (which includes trials from CENTRAL, MEDLINE, Embase, CINAHL, WHO ICTRP, and conference proceedings), ClinicalTrials.gov (16 July 2021), and reference lists of retrieved studies. SELECTION CRITERIA: Randomised controlled trials (RCTs) comparing planned hospital birth with planned home birth in low-risk women as described in the objectives. Cluster-randomised trials, quasi-randomised trials, and trials published only as an abstract were also eligible. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trials for inclusion and risk of bias, extracted data, and checked the data for accuracy. We contacted study authors for additional information. We assessed the certainty of the evidence using the GRADE approach.  MAIN RESULTS: We included one trial involving 11 participants. This was a small feasibility study to show that well-informed women - contrary to common beliefs - were prepared to be randomised. This update did not identify any additional studies for inclusion, but excluded one study that had been awaiting assessment. The included study was at high risk of bias for three out of seven risk of bias domains. The trial did not report on five of the seven primary outcomes, and reported zero events for one primary outcome (caesarean section), and non-zero events for the remaining primary outcome (baby not breastfed). Maternal mortality, perinatal mortality (non-malformed), Apgar < 7 at 5 minutes, transfer to neonatal intensive care unit, and maternal satisfaction were not reported. The overall certainty of the evidence for the two reported primary outcomes was very low according to our GRADE assessment (downgraded two levels for high overall risk of bias (due to high risk of bias arising from lack of blinding, high risk of selective reporting and lack of ability to check for publication bias) and two levels for very serious imprecision (single study with few events)).   AUTHORS' CONCLUSIONS: This review shows that for selected, low-risk pregnant women, the evidence from randomised trials to support that planned hospital birth reduces maternal or perinatal mortality, morbidity, or any other critical outcome is uncertain. As the quality of evidence in favour of home birth from observational studies seems to be steadily increasing, it might be just as important to prepare a regularly updated systematic review including observational studies as described in the Cochrane Handbook for Systematic Reviews of Interventions as to attempt to set up new RCTs. As women and healthcare practitioners may be aware of evidence from observational studies, and as the International Federation of Gynecology and Obstetrics and the International Confederation of Midwives collaboratively conclude that there is strong evidence that out-of-hospital birth supported by a registered midwife is safe, equipoise may no longer exist, and randomised trials may now thus be considered unethical or hardly feasible.


Assuntos
Parto Domiciliar , Morte Perinatal , Gravidez , Lactente , Recém-Nascido , Feminino , Humanos , Gestantes , Parto Domiciliar/efeitos adversos , Revisões Sistemáticas como Assunto , Parto , Hospitais
3.
Skin Res Technol ; 29(3): e13281, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36973979

RESUMO

BACKGROUND: Persons with cosmetic tattoos occasionally experience severe pain and burning sensation on magnetic resonance imaging (MRI). OBJECTIVE: To explore the culprit magnetic substances in commonly used permanent makeup inks. MATERIAL AND METHODS: 20 inks used for cosmetic tattooing of eyebrows, eyeliners, and lips were selected. Ink bottles were tested for magnetic behavior with a neodymium magnet. Eight iron oxide inks qualified for the final study. Metals were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The magnetic fraction of inks was isolated and analyzed by X-ray fluorescence (XRF). Magnetic iron compounds were characterized by Mössbauer spectroscopy and powder X-ray diffraction (XRD). RESULTS: ICP-MS showed iron in all magnetic samples, and some nickel and chromium. Mössbauer spectroscopy and XRD detected ferromagnetic minerals, particularly magnetite, followed by goethite and hematite. CONCLUSION: This original study of cosmetic ink stock products made with iron oxide pigments reports magnetic impurities in inks for cosmetic tattooing, e.g., magnetite, goethite, and hematite. These may be the main cause of MRI burn sensation in cosmetic tattoos. The mechanism behind sensations is hypothesized to be induction of electrical stimuli of axons from periaxonal pigment/impurity activated by magnetic force. Magnetite is considered the lead culprit.


Assuntos
Queimaduras , Tatuagem , Humanos , Tatuagem/efeitos adversos , Óxido Ferroso-Férrico , Tinta , Minerais , Imageamento por Ressonância Magnética , Sensação , Corantes/química
4.
Sensors (Basel) ; 23(14)2023 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-37514869

RESUMO

Acoustic and optical sensing modalities represent two of the primary sensing methods within underwater environments, and both have been researched extensively in previous works. Acoustic sensing is the premier method due to its high transmissivity in water and its relative immunity to environmental factors such as water clarity. Optical sensing is, however, valuable for many operational and inspection tasks and is readily understood by human operators. In this work, we quantify and compare the operational characteristics and environmental effects of turbidity and illumination on two commercial-off-the-shelf sensors and an additional augmented optical method, including: a high-frequency, forward-looking inspection sonar, a stereo camera with built-in stereo depth estimation, and color imaging, where a laser has been added for distance triangulation. The sensors have been compared in a controlled underwater environment with known target objects to ascertain quantitative operation performance, and it is shown that optical stereo depth estimation and laser triangulation operate satisfactorily at low and medium turbidites up to a distance of approximately one meter, with an error below 2 cm and 12 cm, respectively; acoustic measurements are almost completely unaffected up to two meters under high turbidity, with an error below 5 cm. Moreover, the stereo vision algorithm is slightly more robust than laser-line triangulation across turbidity and lighting conditions. Future work will concern the improvement of the stereo reconstruction and laser triangulation by algorithm enhancement and the fusion of the two sensing modalities.

5.
Cochrane Database Syst Rev ; 10: CD010130, 2022 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-36250577

RESUMO

BACKGROUND: Acute respiratory infections (ARIs) are by far the most common reason for prescribing an antibiotic in primary care, even though the majority of ARIs are of viral or non-severe bacterial aetiology. It follows that in many cases antibiotic use will not be beneficial to a patient's recovery but may expose them to potential side effects. Furthermore, limiting unnecessary antibiotic use is a key factor in controlling antibiotic resistance. One strategy to reduce antibiotic use in primary care is point-of-care biomarkers. A point-of-care biomarker (test) of inflammation identifies part of the acute phase response to tissue injury regardless of the aetiology (infection, trauma, or inflammation) and may be used as a surrogate marker of infection, potentially assisting the physician in the clinical decision whether to use an antibiotic to treat ARIs. Biomarkers may guide antibiotic prescription by ruling out a serious bacterial infection and help identify patients in whom no benefit from antibiotic treatment can be anticipated. This is an update of a Cochrane Review first published in 2014. OBJECTIVES: To assess the benefits and harms of point-of-care biomarker tests of inflammation to guide antibiotic treatment in people presenting with symptoms of acute respiratory infections in primary care settings regardless of patient age. SEARCH METHODS: We searched CENTRAL (2022, Issue 6), MEDLINE (1946 to 14 June 2022), Embase (1974 to 14 June 2022), CINAHL (1981 to 14 June 2022), Web of Science (1955 to 14 June 2022), and LILACS (1982 to 14 June 2022). We also searched three trial registries (10 December 2021) for completed and ongoing trials. SELECTION CRITERIA: We included randomised controlled trials (RCTs) in primary care patients with ARIs that compared the use of point-of-care biomarkers with standard care. We included trials that randomised individual participants, as well as trials that randomised clusters of patients (cluster-RCTs). DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data on the following primary outcomes: number of participants given an antibiotic prescription at index consultation and within 28 days follow-up; participant recovery within seven days follow-up; and total mortality within 28 days follow-up. We assessed risk of bias using the Cochrane risk of bias tool and the certainty of the evidence using GRADE. We used random-effects meta-analyses when feasible. We further analysed results with considerable heterogeneity in prespecified subgroups of individual and cluster-RCTs. MAIN RESULTS: We included seven new trials in this update, for a total of 13 included trials. Twelve trials (10,218 participants in total, 2335 of which were children) evaluated a C-reactive protein point-of-care test, and one trial (317 adult participants) evaluated a procalcitonin point-of-care test. The studies were conducted in Europe, Russia, and Asia. Overall, the included trials had a low or unclear risk of bias. However all studies were open-labelled, thereby introducing high risk of bias due to lack of blinding. The use of C-reactive protein point-of-care tests to guide antibiotic prescription likely reduces the number of participants given an antibiotic prescription, from 516 prescriptions of antibiotics per 1000 participants in the control group to 397 prescriptions of antibiotics per 1000 participants in the intervention group (risk ratio (RR) 0.77, 95% confidence interval (CI) 0.69 to 0.86; 12 trials, 10,218 participants; I² = 79%; moderate-certainty evidence).  Overall, use of C-reactive protein tests also reduce the number of participants given an antibiotic prescription within 28 days follow-up (664 prescriptions of antibiotics per 1000 participants in the control group versus 538 prescriptions of antibiotics per 1000 participants in the intervention group) (RR 0.81, 95% CI 0.76 to 0.86; 7 trials, 5091 participants; I² = 29; high-certainty evidence). The prescription of antibiotics as guided by C-reactive protein tests likely does not reduce the number of participants recovered, within seven or 28 days follow-up (567 participants recovered within seven days follow-up per 1000 participants in the control group versus 584 participants recovered within seven days follow-up per 1000 participants in the intervention group) (recovery within seven days follow-up: RR 1.03, 95% CI 0.96 to 1.12; I² = 0%; moderate-certainty evidence) (recovery within 28 days follow-up: RR 1.02, 95% CI 0.79 to 1.32; I² = 0%; moderate-certainty evidence). The use of C-reactive protein tests may not increase total mortality within 28 days follow-up, from 1 death per 1000 participants in the control group to 0 deaths per 1000 participants in the intervention group (RR 0.53, 95% CI 0.10 to 2.92; I² = 0%; low-certainty evidence). We are uncertain as to whether procalcitonin affects any of the primary or secondary outcomes because there were few participants, thereby limiting the certainty of evidence. We assessed the certainty of the evidence as moderate to high according to GRADE for the primary outcomes for C-reactive protein test, except for mortality, as there were very few deaths, thereby limiting the certainty of the evidence. AUTHORS' CONCLUSIONS: The use of C-reactive protein point-of-care tests as an adjunct to standard care likely reduces the number of participants given an antibiotic prescription in primary care patients who present with symptoms of acute respiratory infection. The use of C-reactive protein point-of-care tests likely does not affect recovery rates. It is unlikely that further research will substantially change our conclusion regarding the reduction in number of participants given an antibiotic prescription, although the size of the estimated effect may change.  The use of C-reactive protein point-of-care tests may not increase mortality within 28 days follow-up, but there were very few events. Studies that recorded deaths and hospital admissions were performed in children from low- and middle-income countries and older adults with comorbidities.  Future studies should focus on children, immunocompromised individuals, and people aged 80 years and above with comorbidities. More studies evaluating procalcitonin and potential new biomarkers as point-of-care tests used in primary care to guide antibiotic prescription are needed.  Furthermore, studies are needed to validate C-reactive protein decision algorithms, with a specific focus on potential age group differences.


Assuntos
Antibacterianos , Infecções Respiratórias , Idoso , Antibacterianos/uso terapêutico , Biomarcadores , Proteína C-Reativa/análise , Criança , Humanos , Inflamação , Testes Imediatos , Prescrições , Atenção Primária à Saúde , Pró-Calcitonina/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Infecções Respiratórias/diagnóstico , Infecções Respiratórias/tratamento farmacológico
6.
Tidsskr Nor Laegeforen ; 142(12)2022 09 06.
Artigo em Inglês, Norueguês | MEDLINE | ID: mdl-36066222

RESUMO

A previously healthy woman in her fifties contacted her general practitioner due to a troublesome lump on her hand that had progressed over the course of a year. The final diagnosis surprised those involved and serves as a reminder to both general practitioners and specialists.


Assuntos
Mãos , Feminino , Humanos
7.
J Biol Chem ; 295(2): 517-528, 2020 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-31801825

RESUMO

Two decades of research have uncovered the mechanism by which the complex of tissue factor (TF) and the plasma serine protease factor VIIa (FVIIa) mediates the initiation of blood coagulation. Membrane-anchored TF directly interacts with substrates and induces allosteric effects in the protease domain of FVIIa. These properties are also recapitulated by the soluble ectodomain of TF (sTF). At least two interdependent allosteric activation pathways originate at the FVIIa:sTF interface are proposed to enhance FVIIa activity upon sTF binding. Here, we sought to engineer an sTF-independent FVIIa variant by stabilizing both proposed pathways, with one pathway terminating at segment 215-217 in the activation domain and the other pathway terminating at the N terminus insertion site. To stabilize segment 215-217, we replaced the flexible 170 loop of FVIIa with the more rigid 170 loop from trypsin and combined it with an L163V substitution (FVIIa-VYT). The FVIIa-VYT variant exhibited 60-fold higher amidolytic activity than FVIIa, and displayed similar FX activation and antithrombin inhibition kinetics to the FVIIa.sTF complex. The sTF-independent activity of FVIIa-VYT was partly mediated by an increase in the N terminus insertion and, as shown by X-ray crystallography, partly by Tyr-172 inserting into a cavity in the activation domain stabilizing the S1 substrate-binding pocket. The combination with L163V likely drove additional changes in a delicate hydrogen-bonding network that further stabilized S1-S3 sites. In summary, we report the first FVIIa variant that is catalytically independent of sTF and provide evidence supporting the existence of two TF-mediated allosteric activation pathways.


Assuntos
Coagulação Sanguínea , Fator VIIa/metabolismo , Engenharia de Proteínas , Tromboplastina/metabolismo , Regulação Alostérica , Sequência de Aminoácidos , Cristalografia por Raios X , Fator VIIa/química , Fator VIIa/genética , Humanos , Modelos Moleculares , Mutagênese , Desdobramento de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
8.
Int J Health Geogr ; 19(1): 55, 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-33276781

RESUMO

BACKGROUND: The global financial crisis emerging in 2008 struck Greece especially hard, whereas Scandinavian countries were less affected. This has created a unique opportunity to study the long-term effect of community stress on populations. Increasing frequencies of mental health issues and poorer perceived health among the Greek population have been reported. The physiological marker of long-term stress, cortisol in hair, is applied in this study together with measures of perceived health and stress, depression and anxiety. Our aim was to study self-reported and physiological stress, perceived health, including mental health, in the general population of Greece compared to Scandinavia, in order to assess long-term effects of the economic crisis on these parameters. METHODS: A cross-sectional comparative study of adult (18-65 years) Primary Health Care visitors from semi-rural areas in Greece (n = 84) and Scandinavia (n = 140). Data collection was performed in 2012, and encompassed a questionnaire with a variety of health and stress indicators as well as hair samples for analyzes of cortisol levels. RESULTS: The Greek sample reported significantly poorer overall health (p < 0.0001) than the Scandinavians and a significantly higher perceived stress (p < 0.0001). The Greeks were also less hopeful of the future (p < 0.0001), and to a larger extent fulfilled the HAD criteria for depression (p < 0.0001) and anxiety (p = 0.002). The strongest predictors explaining ill health in logistic regressions were being Greek (p = 0.001) and feeling hopeless about the future p = 0.001, OR = 6.00 (CI 2.10-14.88). Strong predictors in logistic regressions for high perceived stress were anxiety: high (p < 0.0001) and medium (p = 0.0001), as well as medium depression (p = 0.02). CONCLUSIONS: Greek adult Primary Health Care visitors perceived their health more negatively than the Scandinavians, including a higher presence of depression, anxiety, and a lower hope for the future. The Greeks also reported higher perceived stress, but this was not reflected in higher cortisol levels. The findings presented here, identify possible adverse long-term effects of the economic crisis in the examined Greek population that are not seen in the Scandinavian cohort. These differences may also be interpreted against the background of socio-cultural differences in the northern and south-eastern corners of Europe.


Assuntos
Atenção Primária à Saúde , Adulto , Estudos Transversais , Europa (Continente) , Grécia/epidemiologia , Humanos , Países Escandinavos e Nórdicos/epidemiologia
9.
Proc Natl Acad Sci U S A ; 114(47): 12454-12459, 2017 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-29109275

RESUMO

Recombinant factor VIIa (FVIIa) variants with increased activity offer the promise to improve the treatment of bleeding episodes in patients with inhibitor-complicated hemophilia. Here, an approach was adopted to enhance the activity of FVIIa by selectively optimizing substrate turnover at the membrane surface. Under physiological conditions, endogenous FVIIa engages its cell-localized cofactor tissue factor (TF), which stimulates activity through membrane-dependent substrate recognition and allosteric effects. To exploit these properties of TF, a covalent complex between FVIIa and the soluble ectodomain of TF (sTF) was engineered by introduction of a nonperturbing cystine bridge (FVIIa Q64C-sTF G109C) in the interface. Upon coexpression, FVIIa Q64C and sTF G109C spontaneously assembled into a covalent complex with functional properties similar to the noncovalent wild-type complex. Additional introduction of a FVIIa-M306D mutation to uncouple the sTF-mediated allosteric stimulation of FVIIa provided a final complex with FVIIa-like activity in solution, while exhibiting a two to three orders-of-magnitude increase in activity relative to FVIIa upon exposure to a procoagulant membrane. In a mouse model of hemophilia A, the complex normalized hemostasis upon vascular injury at a dose of 0.3 nmol/kg compared with 300 nmol/kg for FVIIa.


Assuntos
Terapia Biológica/métodos , Fator VIIa/química , Hemofilia A/terapia , Engenharia de Proteínas/métodos , Tromboplastina/química , Regulação Alostérica , Animais , Coagulação Sanguínea/efeitos dos fármacos , Modelos Animais de Doenças , Fator VIIa/genética , Fator VIIa/farmacologia , Fator VIIa/uso terapêutico , Feminino , Hemofilia A/fisiopatologia , Humanos , Cinética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Simulação de Dinâmica Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacologia , Proteínas Recombinantes/uso terapêutico , Tromboplastina/genética , Tromboplastina/farmacologia , Tromboplastina/uso terapêutico
10.
Air Med J ; 39(5): 340-342, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33012469

RESUMO

In late 2019, a novel coronavirus was identified as the cause of a cluster of atypical pneumonia cases in Wuhan, China. It subsequently spread throughout China and around the world, quickly becoming a public health emergency. In March 2020, the World Health Organization declared coronavirus disease 2019 a pandemic. This article explores the preparation and early experiences of a large Canadian critical care transport program during the coronavirus disease 2019 pandemic focused on 6 broad strategic objectives centered around staff welfare, regular and transparent communication, networking, evidenced-based approach to personal protective equipment, agile mission planning, and an expedited approach to clinical practice and policy updates and future state modeling.


Assuntos
Comunicação , Infecções por Coronavirus , Cuidados Críticos/organização & administração , Disseminação de Informação , Liderança , Pandemias , Transferência de Pacientes/organização & administração , Pneumonia Viral , Transporte de Pacientes/organização & administração , Medicina Aeroespacial , Resgate Aéreo , Ambulâncias , Betacoronavirus , Colúmbia Britânica , COVID-19 , Prática Clínica Baseada em Evidências , Humanos , Equipamento de Proteção Individual/provisão & distribuição , Resiliência Psicológica , SARS-CoV-2
11.
Biophys J ; 116(10): 1823-1835, 2019 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-31003762

RESUMO

A critical step in injury-induced initiation of blood coagulation is the formation of the complex between the trypsin-like protease coagulation factor VIIa (FVIIa) and its cofactor tissue factor (TF), which converts FVIIa from an intrinsically poor enzyme to an active protease capable of activating zymogens of downstream coagulation proteases. Unlike its constitutively active ancestor trypsin, FVIIa is allosterically activated (by TF). Here, ensemble refinement of crystallographic structures, which uses multiple copies of the entire structure as a means of representing structural flexibility, is applied to explore the impacts of inhibitor binding to trypsin and FVIIa, as well as cofactor binding to FVIIa. To assess the conformational flexibility and its role in allosteric pathways in these proteases, main-chain hydrogen bond networks are analyzed by calculating the hydrogen-bond propensity. Mapping pairwise propensity differences between relevant structures shows that binding of the inhibitor benzamidine to trypsin has a minor influence on the protease flexibility. For FVIIa, in contrast, the protease domain is "locked" into the catalytically competent trypsin-like configuration upon benzamidine binding as indicated by the stabilization of key structural features: the nonprime binding cleft and the oxyanion hole are stabilized, and the effect propagates from the active site region to the calcium-binding site and to the vicinity of the disulphide bridge connecting with the light chain. TF binding to FVIIa furthermore results in stabilization of the 170 loop, which in turn propagates an allosteric signal from the TF-binding region to the active site. Analyses of disulphide bridge energy and flexibility reflect the striking stability difference between the unregulated enzyme and the allosterically activated form after inhibitor or cofactor binding. The ensemble refinement analyses show directly, for the first time to our knowledge, whole-domain structural footprints of TF-induced allosteric networks present in x-ray crystallographic structures of FVIIa, which previously only have been hypothesized or indirectly inferred.


Assuntos
Fator VIIa/química , Fator VIIa/metabolismo , Regulação Alostérica , Apoenzimas/química , Apoenzimas/metabolismo , Benzamidinas/farmacologia , Cristalografia por Raios X , Dissulfetos/química , Ativação Enzimática/efeitos dos fármacos , Modelos Moleculares , Domínios Proteicos , Dobramento de Proteína , Tripsina/química , Tripsina/metabolismo , Tripsinogênio/metabolismo
12.
J Biol Chem ; 291(9): 4671-83, 2016 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-26694616

RESUMO

The complex of coagulation factor VIIa (FVIIa), a trypsin-like serine protease, and membrane-bound tissue factor (TF) initiates blood coagulation upon vascular injury. Binding of TF to FVIIa promotes allosteric conformational changes in the FVIIa protease domain and improves its catalytic properties. Extensive studies have revealed two putative pathways for this allosteric communication. Here we provide further details of this allosteric communication by investigating FVIIa loop swap variants containing the 170 loop of trypsin that display TF-independent enhanced activity. Using x-ray crystallography, we show that the introduced 170 loop from trypsin directly interacts with the FVIIa active site, stabilizing segment 215-217 and activation loop 3, leading to enhanced activity. Molecular dynamics simulations and novel fluorescence quenching studies support that segment 215-217 conformation is pivotal to the enhanced activity of the FVIIa variants. We speculate that the allosteric regulation of FVIIa activity by TF binding follows a similar path in conjunction with protease domain N terminus insertion, suggesting a more complete molecular basis of TF-mediated allosteric enhancement of FVIIa activity.


Assuntos
Fator VIIa/metabolismo , Modelos Moleculares , Tromboplastina/metabolismo , Tripsina/metabolismo , Regulação Alostérica , Domínio Catalítico , Cristalografia por Raios X , Estabilidade Enzimática , Fator VIIa/química , Fator VIIa/genética , Humanos , Cinética , Simulação de Dinâmica Molecular , Mutação , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Desdobramento de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Solubilidade , Tromboplastina/química , Tromboplastina/genética , Tripsina/química , Tripsina/genética
13.
Nature ; 477(7365): 466-70, 2011 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-21849977

RESUMO

Broadly neutralizing antibodies against highly variable viral pathogens are much sought after to treat or protect against global circulating viruses. Here we probed the neutralizing antibody repertoires of four human immunodeficiency virus (HIV)-infected donors with remarkably broad and potent neutralizing responses and rescued 17 new monoclonal antibodies that neutralize broadly across clades. Many of the new monoclonal antibodies are almost tenfold more potent than the recently described PG9, PG16 and VRC01 broadly neutralizing monoclonal antibodies and 100-fold more potent than the original prototype HIV broadly neutralizing monoclonal antibodies. The monoclonal antibodies largely recapitulate the neutralization breadth found in the corresponding donor serum and many recognize novel epitopes on envelope (Env) glycoprotein gp120, illuminating new targets for vaccine design. Analysis of neutralization by the full complement of anti-HIV broadly neutralizing monoclonal antibodies now available reveals that certain combinations of antibodies should offer markedly more favourable coverage of the enormous diversity of global circulating viruses than others and these combinations might be sought in active or passive immunization regimes. Overall, the isolation of multiple HIV broadly neutralizing monoclonal antibodies from several donors that, in aggregate, provide broad coverage at low concentrations is a highly positive indicator for the eventual design of an effective antibody-based HIV vaccine.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , HIV/classificação , HIV/imunologia , Vacinas contra a AIDS/biossíntese , Vacinas contra a AIDS/imunologia , Anticorpos Monoclonais/imunologia , Linhagem Celular , Mapeamento de Epitopos , Epitopos/química , Epitopos/imunologia , Glicoproteínas/química , Glicoproteínas/imunologia , Glicosilação , Células HEK293 , HIV/isolamento & purificação , Infecções por HIV/imunologia , Infecções por HIV/terapia , Proteínas do Vírus da Imunodeficiência Humana/química , Proteínas do Vírus da Imunodeficiência Humana/imunologia , Humanos , Soros Imunes/sangue , Soros Imunes/imunologia , Dados de Sequência Molecular , Testes de Neutralização
14.
Biochem J ; 473(15): 2395-411, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27208168

RESUMO

Coagulation Factor IX is positioned at the merging point of the intrinsic and extrinsic blood coagulation cascades. Factor IXa (activated Factor IX) serves as the trigger for amplification of coagulation through formation of the so-called Xase complex, which is a ternary complex of Factor IXa, its substrate Factor X and the cofactor Factor VIIIa on the surface of activated platelets. Within the Xase complex the substrate turnover by Factor IXa is enhanced 200000-fold; however, the mechanistic and structural basis for this dramatic enhancement remains only partly understood. A multifaceted approach using enzymatic, biophysical and crystallographic methods to evaluate a key set of activity-enhanced Factor IXa variants has demonstrated a delicately balanced bidirectional network. Essential molecular interactions across multiple regions of the Factor IXa molecule co-operate in the maturation of the active site. This maturation is specifically facilitated by long-range communication through the Ile(212)-Ile(213) motif unique to Factor IXa and a flexibility of the 170-loop that is further dependent on the conformation in the Cys(168)-Cys(182) disulfide bond. Ultimately, the network consists of compensatory brakes (Val(16) and Ile(213)) and accelerators (Tyr(99) and Phe(174)) that together allow for a subtle fine-tuning of enzymatic activity.


Assuntos
Fator IXa/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Biocatálise , Ativação Enzimática , Fator IXa/química , Humanos , Modelos Moleculares , Plasmídeos , Conformação Proteica , Dobramento de Proteína , Proteólise , Homologia de Sequência de Aminoácidos , Espectrometria de Fluorescência
15.
Scand J Prim Health Care ; 35(4): 313-321, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29183265

RESUMO

OBJECTIVE: To explore how general practitioners (GPs) think and act when presented with new evidence in relation to planned home birth and a proposal to change information practices. DESIGN: Exploratory ethnographic study of GPs. The GPs were encountered one or more times during a two-year period, 2011-2013, while the author tried to set up formal focus group interviews. Dialogues about the evidence, personal experiences, values and other issues unavoidably occurred. Field notes were written concomitantly. SETTING: Danish GPs, primarily in Copenhagen. SUBJECTS: Fifty Danish GPs. RESULTS: The GPs reacted very differently, both spontaneously and later. Spontaneous reactions were often emotional involving private and professional experiences whereas later reactions were more influenced by rational deliberations. Approximately half the GPs (n = 18) who were asked whether they would personally hand out the local information leaflet about home birth were prepared to do so. The time lag between presentation of the evidence and the GPs' decision to hand out the leaflets was up to one and a half year. CONCLUSIONS: A significant number of GPs were prepared to change their information practices. However, for many GPs, the new evidence challenged previous perceptions, and ample time and resources for dialogue, deliberations and adaptation to local circumstances were required to accommodate change. IMPLICATIONS: Changing information practices on a larger scale will require a systematic approach involving key stakeholders. Key Points Current awareness•Patients and pregnant women should receive evidence-based information about possible choices of care - also in relation to place of birth. Most important results•Doctors often find the new evidence supporting planned home birth counterintuitive and spontaneously react emotionally rather than rationally to the evidence.•The new evidence challenging previous views elicits fast, emotional reactions, later deliberate reflections, perhaps cognitive dissonance and, finally, for some, change in clinical practice. Significance for the readers•The findings may be applicable to other fields where an evidence-based choice between an interventionist and a conservative approach is relevant.


Assuntos
Atitude do Pessoal de Saúde , Medicina Baseada em Evidências , Clínicos Gerais , Parto Domiciliar , Educação de Pacientes como Assunto , Padrões de Prática Médica , Adulto , Tomada de Decisões , Dinamarca , Feminino , Grupos Focais , Humanos , Gravidez , Pesquisa Qualitativa
17.
J Biol Chem ; 290(10): 6620-9, 2015 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-25564618

RESUMO

ADAMDEC1 is a proteolytically active metzincin metalloprotease displaying rare active site architecture with a zinc-binding Asp residue (Asp-362). We previously demonstrated that substitution of Asp-362 for a His residue, thereby reconstituting the canonical metzincin zinc-binding environment with three His zinc ligands, increases the proteolytic activity. The protease also has an atypically short domain structure with an odd number of Cys residues in the metalloprotease domain. Here, we investigated how these rare structural features in the ADAMDEC1 metalloprotease domain impact the proteolytic activity, the substrate specificity, and the effect of inhibitors. We identified carboxymethylated transferrin (Cm-Tf) as a new ADAMDEC1 substrate and determined the primary and secondary cleavage sites, which suggests a strong preference for Leu in the P1' position. Cys(392), present in humans but only partially conserved within sequenced ADAMDEC1 orthologs, was found to be unpaired, and substitution of Cys(392) for a Ser increased the reactivity with α2-macroglobulin but not with casein or Cm-Tf. Substitution of Asp(362) for His resulted in a general increase in proteolytic activity and a change in substrate specificity was observed with Cm-Tf. ADAMDEC1 was inhibited by the small molecule inhibitor batimastat but not by tissue inhibitor of metalloproteases (TIMP)-1, TIMP-2, or the N-terminal inhibitory domain of TIMP-3 (N-TIMP-3). However, N-TIMP-3 displayed profound inhibitory activity against the D362H variants with a reconstituted consensus metzincin zinc-binding environment. We hypothesize that these unique features of ADAMDEC1 may have evolved to escape from inhibition by endogenous metalloprotease inhibitors.


Assuntos
Proteínas ADAM/química , Domínio Catalítico , Metaloproteases/química , Inibidores Teciduais de Metaloproteinases/química , Proteínas ADAM/antagonistas & inibidores , Proteínas ADAM/genética , Sequência de Aminoácidos/genética , Cristalografia por Raios X , Regulação Enzimológica da Expressão Gênica , Humanos , Metaloproteases/antagonistas & inibidores , Metaloproteases/genética , Estrutura Terciária de Proteína , Proteólise , Especificidade por Substrato , Inibidores Teciduais de Metaloproteinases/metabolismo , Zinco/química
18.
J Biol Chem ; 290(27): 16463-76, 2015 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-25903134

RESUMO

Lysine residues are implicated in driving the ligand binding to the LDL receptor family. However, it has remained unclear how specificity is regulated. Using coagulation factor VIII as a model ligand, we now study the contribution of individual lysine residues in the interaction with the largest member of the LDL receptor family, low-density lipoprotein receptor-related protein (LRP1). Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and SPR interaction analysis on a library of lysine replacement variants as two independent approaches, we demonstrate that the interaction between factor VIII (FVIII) and LRP1 occurs over an extended surface containing multiple lysine residues. None of the individual lysine residues account completely for LRP1 binding, suggesting an additive binding model. Together with structural docking studies, our data suggest that FVIII interacts with LRP1 via an extended surface of multiple lysine residues that starts at the bottom of the C1 domain and winds around the FVIII molecule.


Assuntos
Fator VIII/química , Fator VIII/metabolismo , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/química , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Lisina/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Medição da Troca de Deutério , Endocitose , Fator VIII/genética , Humanos , Lipoproteínas LDL/metabolismo , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Lisina/química , Lisina/genética , Espectrometria de Massas , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína
19.
Scand J Gastroenterol ; 51(7): 855-9, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27000415

RESUMO

OBJECTIVE: The aim of this study was to describe feasibility, postoperative morbidity, and histological outcome of transanal minimally-invasive surgery (TAMIS) in patients with rectal adenoma. MATERIAL AND METHODS: All patients who underwent TAMIS at a single institution from December 2011 to December 2015 were retrospectively included in the study. Feasibility was based on tumor size, distance of tumor from the anal verge, operative time, and hospital stay. Thirty-day morbidity was defined by the revised Accordion Classification system. Histological outcome included microscopic resection margin status, specimen fragmentation status, and grading of dysplasia in rectal adenoma. RESULTS: A total of 51 patients with rectal adenoma underwent TAMIS. The median tumor diameter was 32 (4-60) mm and the median distance from the anal verge 8 (3-14) cm. Median operative time was 40 (13-116) min and median length of hospital stay was 1 (0-25) days. Overall morbidity was 12% (four grade 1, one grade 2, and one grade 3 complications). 22% had a positive resection margin, whereas 31% had an indefinable resection margin status mostly due to tissue fragmentation. Median follow-up time was 7 (0-40) months. CONCLUSIONS: TAMIS is a challenging surgical technique for treatment of rectal adenoma. Our initial experience among 51 patients resulted in a high proportion of positive resection margins and a high fragmentation rate. The role of TAMIS in the treatment of rectal adenoma is to be defined through comparative studies.


Assuntos
Adenoma/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos , Neoplasias Retais/cirurgia , Adenoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Complicações Pós-Operatórias , Proctoscopia , Neoplasias Retais/patologia , Estudos Retrospectivos
20.
Nature ; 463(7280): 549-53, 2010 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-20111001

RESUMO

Heat shock protein 70 (Hsp70) is an evolutionarily highly conserved molecular chaperone that promotes the survival of stressed cells by inhibiting lysosomal membrane permeabilization, a hallmark of stress-induced cell death. Clues to its molecular mechanism of action may lay in the recently reported stress- and cancer-associated translocation of a small portion of Hsp70 to the lysosomal compartment. Here we show that Hsp70 stabilizes lysosomes by binding to an endolysosomal anionic phospholipid bis(monoacylglycero)phosphate (BMP), an essential co-factor for lysosomal sphingomyelin metabolism. In acidic environments Hsp70 binds with high affinity and specificity to BMP, thereby facilitating the BMP binding and activity of acid sphingomyelinase (ASM). The inhibition of the Hsp70-BMP interaction by BMP antibodies or a point mutation in Hsp70 (Trp90Phe), as well as the pharmacological and genetic inhibition of ASM, effectively revert the Hsp70-mediated stabilization of lysosomes. Notably, the reduced ASM activity in cells from patients with Niemann-Pick disease (NPD) A and B-severe lysosomal storage disorders caused by mutations in the sphingomyelin phosphodiesterase 1 gene (SMPD1) encoding for ASM-is also associated with a marked decrease in lysosomal stability, and this phenotype can be effectively corrected by treatment with recombinant Hsp70. Taken together, these data open exciting possibilities for the development of new treatments for lysosomal storage disorders and cancer with compounds that enter the lysosomal lumen by the endocytic delivery pathway.


Assuntos
Proteínas de Choque Térmico HSP70/metabolismo , Lisossomos/metabolismo , Lisossomos/patologia , Doenças de Niemann-Pick/metabolismo , Doenças de Niemann-Pick/patologia , Linhagem Celular Tumoral , Células Cultivadas , Humanos , Concentração de Íons de Hidrogênio , Membranas Intracelulares/metabolismo , Lisofosfolipídeos/metabolismo , Monoglicerídeos/metabolismo , Esfingomielina Fosfodiesterase/metabolismo
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