Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 96
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Faraday Discuss ; 249(0): 50-68, 2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-37799072

RESUMO

Vibrational spectroscopy is a powerful approach to visualising interfacial phenomena. However, extracting structural and dynamical information from vibrational spectra is a challenge that requires first-principles simulations, including non-Condon and quantum nuclear effects. We address this challenge by developing a machine-learning enhanced first-principles framework to speed up predictive modelling of infrared, Raman, and sum-frequency generation spectra. Our approach uses machine learning potentials that encode quantum nuclear effects to generate quantum trajectories using simple molecular dynamics efficiently. In addition, we reformulate bulk and interfacial selection rules to express them unambiguously in terms of the derivatives of polarisation and polarisabilities of the whole system and predict these derivatives efficiently using fully-differentiable machine learning models of dielectric response tensors. We demonstrate our framework's performance by predicting the IR, Raman, and sum-frequency generation spectra of liquid water, ice and the water-air interface by achieving near quantitative agreement with experiments at nearly the same computational efficiency as pure classical methods. Finally, to aid the experimental discovery of new phases of nanoconfined water, we predict the temperature-dependent vibrational spectra of monolayer water across the solid-hexatic-liquid phases transition.

2.
J Chem Phys ; 159(4)2023 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-37522405

RESUMO

The MACE architecture represents the state of the art in the field of machine learning force fields for a variety of in-domain, extrapolation, and low-data regime tasks. In this paper, we further evaluate MACE by fitting models for published benchmark datasets. We show that MACE generally outperforms alternatives for a wide range of systems, from amorphous carbon, universal materials modeling, and general small molecule organic chemistry to large molecules and liquid water. We demonstrate the capabilities of the model on tasks ranging from constrained geometry optimization to molecular dynamics simulations and find excellent performance across all tested domains. We show that MACE is very data efficient and can reproduce experimental molecular vibrational spectra when trained on as few as 50 randomly selected reference configurations. We further demonstrate that the strictly local atom-centered model is sufficient for such tasks even in the case of large molecules and weakly interacting molecular assemblies.

3.
Int J Environ Health Res ; 32(6): 1183-1191, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33256462

RESUMO

Aflatoxins are naturally occurring food toxins known to contaminate cereals with a carry-over effect in milk and meat products from farm animals raised on contaminated feed. In children, continuous consumption of aflatoxin-contaminated food is linked to immune suppression, vaccine interference and growth faltering while in adult populations, carcinogenesis in the liver has been established. We evaluate the main determinants of aflatoxin exposures among children recruited from primary schools in Makueni and Siaya Counties. A five-part questionnaire was administered to collect information from randomly selected participants. AflatoxinB1-lysine adducts in children's sera and total aflatoxins in food samples were analyzed by High-Performance Liquid Chromatography with Fluorescence detection. Using Chi-squared tests and Kruskal-Wallis tests, children from low-income households had the highest aflatoxin exposure, p-value = 0.0029. Smaller family size, greater food diversity, and good farming practices were associated with low aflatoxin exposures p < 0.001. Individual households living under severe levels of poverty were evidently exposed to higher levels of aflatoxins.


Assuntos
Aflatoxinas , Aflatoxinas/análise , Aflatoxinas/toxicidade , Animais , Criança , Cromatografia Líquida de Alta Pressão , Contaminação de Alimentos/análise , Humanos , Quênia , Leite
4.
Org Biomol Chem ; 19(25): 5577-5588, 2021 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-34085692

RESUMO

Laxaphycins are a family of cyclic lipopeptides with synergistic antifungal and antiproliferative activities. They are produced by multiple cyanobacterial genera and comprise two sets of structurally unrelated 11- and 12-residue macrocyclic lipopeptides. Here, we report the discovery of new antifungal laxaphycins from Nostoc sp. UHCC 0702, which we name heinamides, through antimicrobial bioactivity screening. We characterized the chemical structures of eight heinamide structural variants A1-A3 and B1-B5. These variants contain the rare non-proteinogenic amino acids 3-hydroxy-4-methylproline, 4-hydroxyproline, 3-hydroxy-d-leucine, dehydrobutyrine, 5-hydroxyl ß-amino octanoic acid, and O-carbamoyl-homoserine. We obtained an 8.6-Mb complete genome sequence from Nostoc sp. UHCC 0702 and identified the 93 kb heinamide biosynthetic gene cluster. The structurally distinct heinamides A1-A3 and B1-B5 variants are synthesized using an unusual branching biosynthetic pathway. The heinamide biosynthetic pathway also encodes several enzymes that supply non-proteinogenic amino acids to the heinamide synthetase. Through heterologous expression, we showed that (2S,4R)-4-hydroxy-l-proline is supplied through the action of a novel enzyme LxaN, which hydroxylates l-proline. 11- and 12-residue heinamides have the characteristic synergistic activity of laxaphycins against Aspergillus flavus FBCC 2467. Structural and genetic information of heinamides may prove useful in future discovery of natural products and drug development.


Assuntos
Lipopeptídeos
5.
BMC Geriatr ; 21(1): 138, 2021 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-33627069

RESUMO

BACKGROUND: For the rising number of people living with dementia, cost-effective community-based interventions to support psychosocial care are needed. The FindMyApps intervention has been developed with and for people with dementia and their caregivers, to help them use tablets to facilitate self-management and engagement in meaningful social activities. A feasibility study and exploratory pilot trial evaluating FindMyApps have been carried out. This definitive trial further evaluates the effectiveness of the intervention and, for the first time, the cost-effectiveness. METHODS: A randomized controlled non-blinded single-center two-arm superiority trial will be conducted. Community-dwelling people with Mild Cognitive Impairment (MCI), or dementia with a Mini Mental-State Examination (MMSE) of > 17 and < 26, or Global Deterioration Scale 3 or 4, with an informal caregiver and access to a wireless internet connection will be included. In total, 150 patient-caregiver dyads will be randomly allocated to receive either usual care (control arm - tablet computer; n = 75 dyads) or usual care and the FindMyApps intervention (experimental arm - tablet computer and FindMyApps; n = 75 dyads). The primary outcomes are: for people with dementia, self-management and social participation; for caregivers, sense of competence. In addition to a main effect analysis, a cost-effectiveness analysis will be performed. In line with MRC guidance for evaluation of complex interventions a process evaluation will also be undertaken. DISCUSSION: Results of the trial are expected to be available in 2023 and will be submitted for publication in international peer-reviewed scientific journals, in addition to conference presentations and reporting via the EU Marie Sklodowska-Curie DISTINCT ITN network. By providing evidence for or against the effectiveness and cost-effectiveness of the FindMyApps intervention, the results of the trial will influence national implementation of FindMyApps. We hope that the results of the trial will further stimulate research and development at the intersection of technology and psycho-social care in dementia. We hope to further demonstrate that the randomized controlled trial is a valuable and feasible means of evaluating new digital technologies, to stimulate further high-quality research in this growing field. TRIAL REGISTRATION NUMBER: Netherlands Trial Register: NL8157 ; registered 15th November 2019.


Assuntos
Demência , Autogestão , Cuidadores , Análise Custo-Benefício , Demência/diagnóstico , Demência/terapia , Humanos , Vida Independente , Países Baixos , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Participação Social
6.
J Theor Biol ; 486: 110097, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-31790680

RESUMO

Chemical evolution is essential in understanding the origins of life. We present a theory for the evolution of molecule masses and show that small molecules grow by random diffusion and large molecules by a preferential attachment process leading eventually to life's molecules. It reproduces correctly the distribution of molecules found via mass spectroscopy for the Murchison meteorite and estimates the start of chemical evolution back to 12.8 billion years following the birth of stars and supernovae. From the Frontier mass between the random and preferential attachment dynamics the birth time of molecule families can be estimated. Amino acids emerge about 165 million years after chemical elements emerge in stars. Using the scaling of reaction rates with the distance of the molecules in space we recover correctly the few days emergence time of amino acids in the Miller-Urey experiment. The distribution of interstellar and extragalactic molecules are both consistent with the evolutionary mass distribution, and their age is estimated to 108 and 65 million years after the start of evolution. From the model, we can determine the number of different molecule compositions at the time of the emergence of Earth to be 1.6 million and the number of molecule compositions in interstellar space to a mere 719 species.


Assuntos
Evolução Química , Meteoroides , Aminoácidos , Humanos , Origem da Vida
7.
J Invertebr Pathol ; 172: 107351, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32171803

RESUMO

Parasite transmission plays a central role in disease dynamics, but little is known about the extent to which direct and indirect transmission contributes to disease dynamics in group-living animals. Quantifying transmission by contact or exposure is challenging, as direct measurements of pathogen transmission are often impractical and individual behaviour is largely unknown. Here, we attempt to tackle these twin problems through the use of a generalist entomopathogenic fungus Metarhizium robertsii to study direct and indirect transmission in the black carpenter ant Camponotus pennsylvanicus. We provide evidence that large quantities of fungal conidia (spores) can be acquired over time on the ant's cuticle and significant amounts are shed into the environment, allowing indirect transmission. Unexposed ants in the nest can be infected either through direct (i.e. social contacts) or indirect (i.e. acquisition from the environment) transmission, potentially leading to the same mortality as if all individuals of a nest would have been directly exposed to the pathogen. Our findings highlight the importance of indirect transmission routes in a species of social living organisms.


Assuntos
Formigas/microbiologia , Metarhizium/fisiologia , Esporos Fúngicos/fisiologia , Animais , Comportamento Animal , Comportamento Social
8.
Thorax ; 74(7): 650-658, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31028237

RESUMO

RATIONALE: While cross-sectional studies have shown associations between certain occupational exposures and lower levels of lung function, there was little evidence from population-based studies with repeated lung function measurements. OBJECTIVES: We aimed to investigate the associations between occupational exposures and longitudinal lung function decline in the population-based Tasmanian Longitudinal Health Study. METHODS: Lung function decline between ages 45 years and 50 years was assessed using data from 767 participants. Using lifetime work history calendars completed at age 45 years, exposures were assigned according to the ALOHA plus Job Exposure Matrix. Occupational exposures were defined as ever exposed and cumulative exposure -unit- years. We investigated effect modification by sex, smoking and asthma status. RESULTS: Compared with those without exposure, ever exposures to aromatic solvents and metals were associated with a greater decline in FEV1 (aromatic solvents 15.5 mL/year (95% CI -24.8 to 6.3); metals 11.3 mL/year (95% CI -21.9 to - 0.7)) and FVC (aromatic solvents 14.1 mL/year 95% CI -28.8 to - 0.7; metals 17.5 mL/year (95% CI -34.3 to - 0.8)). Cumulative exposure (unit years) to aromatic solvents was also associated with greater decline in FEV1 and FVC. Women had lower cumulative exposure years to aromatic solvents than men (mean (SD) 9.6 (15.5) vs 16.6 (14.6)), but greater lung function decline than men. We also found association between ever exposures to gases/fumes or mineral dust and greater decline in lung function. CONCLUSIONS: Exposures to aromatic solvents and metals were associated with greater lung function decline. The effect of aromatic solvents was strongest in women. Preventive strategies should be implemented to reduce these exposures in the workplace.


Assuntos
Pulmão/efeitos dos fármacos , Pulmão/fisiopatologia , Exposição Ocupacional/efeitos adversos , Solventes/efeitos adversos , Adulto , Envelhecimento/fisiologia , Feminino , Volume Expiratório Forçado/efeitos dos fármacos , Volume Expiratório Forçado/fisiologia , Inquéritos Epidemiológicos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Exposição Ocupacional/análise , Fatores Sexuais , Solventes/análise , Capacidade Vital/efeitos dos fármacos , Capacidade Vital/fisiologia
9.
Biomarkers ; 24(4): 379-388, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30821509

RESUMO

Context: Fumonisins (FNs), a group of mycotoxins produced mainly by Fusarium species, are ubiquitous food contaminants, especially for maize. Fumonisin B1 (FB1) caused severe toxicities in farm animals, induced kidney and liver tumours in rodents and is associated with many human adverse health effects, including oesophageal cancer. International Agency for Research on Cancer (IARC) categorizes FB1 as a possible human carcinogen (Group 2B). Inhibition of ceramide synthesis and disruption of sphingolipids metabolism are well studied as the major mechanisms of FB1-induced toxicity. Increases in sphinganine (Sa) and decrease in sphingosine (So) levels and their ratio are validated biomarkers of FB1 effects. Methods: In this study, we measured urinary levels of Sa, So and Sa/So in 284 children aged 1-14 years who consume maize as a staple diet. Exfoliated cells from urine were processed and sphingolipids quantified by High Pressure Liquid Chromatography. Results and conclusions: Sa and So were detectable in 95.07% and 98.94% of samples, respectively. Creatinine adjusted mean levels and standard deviation of Sa, So and Sa/So ratio were 1.23 ± 2.18, 4.99 ± 8.3 and 0.296 ± 0.587 nM. These results further confirmed the findings in studies with human adults, i.e. urinary Sa, So levels and Sa/So ratio are good biomarkers to assess FNs exposure in children.


Assuntos
Arachis/química , Carcinógenos Ambientais/toxicidade , Fumonisinas/toxicidade , Esfingosina/análogos & derivados , Esfingosina/urina , Zea mays/química , Adolescente , Biomarcadores/urina , Carcinógenos Ambientais/metabolismo , Criança , Pré-Escolar , Creatinina/urina , Dieta , Feminino , Contaminação de Alimentos , Fumonisinas/metabolismo , Humanos , Lactente , Quênia , Metabolismo dos Lipídeos , Masculino
10.
Thorax ; 72(11): 990-997, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28687678

RESUMO

RATIONALE: Population-based studies have found evidence of a relationship between occupational exposures and Chronic Obstructive Pulmonary Disease (COPD), but these studies are limited by the use of prebronchodilator spirometry. Establishing this link using postbronchodilator is critical, because occupational exposures are a modifiable risk factor for COPD. OBJECTIVES: To investigate the associations between occupational exposures and fixed airflow obstruction using postbronchodilator spirometry. METHODS: One thousand three hundred and thirty-five participants were included from 2002 to 2008 follow-up of the Tasmanian Longitudinal Health Study (TAHS). Spirometry was performed and lifetime work history calendars were used to collect occupational history. ALOHA plus Job Exposure Matrix was used to assign occupational exposure, and defined as ever exposed and cumulative exposure unit (EU)-years. Fixed airflow obstruction was defined by postbronchodilator FEV1/FVC <0.7 and the lower limit of normal (LLN). Multinomial logistic regressions were used to investigate potential associations while controlling for possible confounders. RESULTS: Ever exposure to biological dust (relative risk (RR)=1.58, 95% CI 1.01 to 2.48), pesticides (RR=1.74,95% CI 1.00 to 3.07) and herbicides (RR=2.09,95% CI 1.18 to 3.70) were associated with fixed airflow obstruction. Cumulative EU-years to all pesticides (RR=1.11,95% CI 1.00 to 1.25) and herbicides (RR=1.15,95% CI 1.00 to 1.32) were also associated with fixed airflow obstruction. In addition, all pesticides exposure was consistently associated with chronic bronchitis and symptoms that are consistent with airflow obstruction. Ever exposure to mineral dust, gases/fumes and vapours, gases, dust or fumes were only associated with fixed airflow obstruction in non-asthmatics only. CONCLUSIONS: Pesticides and herbicides exposures were associated with fixed airflow obstruction and chronic bronchitis. Biological dust exposure was also associated with fixed airflow obstruction in non-asthmatics. Minimising occupational exposure to these agents may help to reduce the burden of COPD.


Assuntos
Exposição Ocupacional/efeitos adversos , Praguicidas/toxicidade , Doença Pulmonar Obstrutiva Crônica/induzido quimicamente , Adulto , Feminino , Seguimentos , Volume Expiratório Forçado , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Prevalência , Doença Pulmonar Obstrutiva Crônica/epidemiologia , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Fatores de Risco , Fumar/efeitos adversos , Espirometria , Inquéritos e Questionários , Tasmânia/epidemiologia
11.
Blood ; 125(3): 534-41, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25414439

RESUMO

Many red cell polymorphisms are a result of selective pressure by the malarial parasite. Here, we add another red cell disease to the panoply of erythrocytic changes that give rise to resistance to malaria. Erythrocytes from individuals with erythropoietic protoporphyria (EPP) have low levels of the final enzyme in the heme biosynthetic pathway, ferrochelatase. Cells from these patients are resistant to the growth of Plasmodium falciparum malarial parasites. This phenomenon is due to the absence of ferrochelatase and not an accumulation of substrate, as demonstrated by the normal growth of P falciparum parasites in the EPP phenocopy, X-linked dominant protoporphyria, which has elevated substrate, and normal ferrochelatase levels. This observation was replicated in a mouse strain with a hypomorphic mutation in the murine ferrochelatase gene. The parasite enzyme is not essential for parasite growth as Plasmodium berghei parasites carrying a complete deletion of the ferrochelatase gene grow normally in erythrocytes, which confirms previous studies. That ferrochelatase is essential to parasite growth was confirmed by showing that inhibition of ferrochelatase using the specific competitive inhibitor, N-methylprotoporphyrin, produced a potent growth inhibition effect against cultures of P falciparum. This raises the possibility of targeting human ferrochelatase in a host-directed antimalarial strategy.


Assuntos
Eritrócitos/parasitologia , Ferroquelatase/fisiologia , Malária Falciparum/prevenção & controle , Plasmodium berghei/crescimento & desenvolvimento , Protoporfiria Eritropoética/prevenção & controle , Animais , Eritrócitos/enzimologia , Feminino , Ferroquelatase/antagonistas & inibidores , Heme/metabolismo , Humanos , Malária Falciparum/enzimologia , Malária Falciparum/parasitologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fenótipo , Protoporfiria Eritropoética/enzimologia , Protoporfiria Eritropoética/parasitologia , Protoporfirinas/farmacologia
13.
Sensors (Basel) ; 17(1)2016 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-28042846

RESUMO

Point cloud registration is a key process in multi-view 3D measurements. Its precision affects the measurement precision directly. However, in the case of the point clouds with non-overlapping areas or curvature invariant surface, it is difficult to achieve a high precision. A high precision registration method based on sphere feature constraint is presented to overcome the difficulty in the paper. Some known sphere features with constraints are used to construct virtual overlapping areas. The virtual overlapping areas provide more accurate corresponding point pairs and reduce the influence of noise. Then the transformation parameters between the registered point clouds are solved by an optimization method with weight function. In that case, the impact of large noise in point clouds can be reduced and a high precision registration is achieved. Simulation and experiments validate the proposed method.

14.
Angew Chem Int Ed Engl ; 55(11): 3596-9, 2016 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-26846478

RESUMO

Cyanobactins are a rapidly growing family of linear and cyclic peptides produced by cyanobacteria. Kawaguchipeptins A and B, two macrocyclic undecapeptides reported earlier from Microcystis aeruginosa NIES-88, are shown to be products of the cyanobactin biosynthetic pathway. The 9 kb kawaguchipeptin (kgp) gene cluster was identified in a 5.26 Mb draft genome of Microcystis aeruginosa NIES-88. We verified that this gene cluster is responsible for the production of the kawaguchipeptins through heterologous expression of the kgp gene cluster in Escherichia coli. The KgpF prenyltransferase was overexpressed and was shown to prenylate C-3 of Trp residues in both linear and cyclic peptides in vitro. Our findings serve to further enhance the structural diversity of cyanobactins to include tryptophan-prenylated cyclic peptides.


Assuntos
Dimetilaliltranstransferase/metabolismo , Triptofano/metabolismo , Sequência de Aminoácidos , Dimetilaliltranstransferase/química , Escherichia coli/genética , Genoma Bacteriano , Microcystis/genética , Família Multigênica
15.
Sex Transm Infect ; 91(3): 178-82, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25182158

RESUMO

OBJECTIVES: This study aims to investigate the levels and correlates of unprotected anal intercourse (UAI), drug and alcohol use, and HIV testing among Vietnamese men who have sex with men (MSM). METHODS: A total of 381 MSM were recruited in a community-based cross-sectional survey in two towns (Long Xuyen and Chau Doc) in An Giang province in 2009 by using a two-stage cluster sampling. Face-to-face interviews were conducted to elicit respondents' characteristics. Regression analysis was used to determine the correlates of key behavioural outcomes. RESULTS: In the month before being interviewed, 19.9% respondents had used drugs (13.6% injected), 25.2% had consumed alcohol daily and 33.9% had a UAI with ≥2 male partners. Only 19.2% were tested for HIV in the 12 months before being interviewed. Injecting drug use was significantly associated with having sexual partners who also inject, whereas daily alcohol consumption was associated with an ever-married/cohabiting with women, being transgender and having had at least three male partners in the previous 3 months. Transactional sex, weekly alcohol use, early sexual debut and perception of being at higher risk of HIV infection were correlates of UAI in multiple partnerships. MSM who self-identified as not being gay and those who perceived themselves to be at low risk of HIV infection were less likely to test for HIV. CONCLUSIONS: Due to the scarcity of effective MSM-targeted prevention programmes, it is likely that substance use, risky sexual behaviours and low testing uptake may substantially contribute to the spread of HIV among Vietnamese MSM sampled. Harm reduction programmes targeting MSM, and in particular injecting MSM, should be rolled-out in this province.


Assuntos
Alcoolismo/epidemiologia , Infecções por HIV/diagnóstico , Serviços de Saúde/estatística & dados numéricos , Homossexualidade Masculina , Assunção de Riscos , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Adolescente , Adulto , Estudos Transversais , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/transmissão , Humanos , Entrevistas como Assunto , Masculino , Vietnã/epidemiologia , Adulto Jovem
16.
Blood ; 120(2): 424-30, 2012 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-22510876

RESUMO

Splenic sequestration of RBCs with reduced surface area and cellular deformability has long been recognized as contributing to pathogenesis of several RBC disorders, including hereditary spherocytosis. However, the quantitative relationship between the extent of surface area loss and splenic entrapment remains to be defined. To address this issue, in the present study, we perfused ex vivo normal human spleens with RBCs displaying various degrees of surface area loss and monitored the kinetics of their splenic retention. Treatment with increasing concentrations of lysophosphatidylcholine resulted in a dose-dependent reduction of RBC surface area at constant volume, increased osmotic fragility, and decreased deformability. The degree of splenic retention of treated RBCs increased with increasing surface area loss. RBCs with a > 18% average surface area loss (> 27% reduced surface area-to-volume ratio) were rapidly and completely entrapped in the spleen. Surface-deficient RBCs appeared to undergo volume loss after repeated passages through the spleen and escape from splenic retention. The results of the present study for the first time define the critical extent of surface area loss leading to splenic entrapment and identify an adaptive volume regulation mechanism that allows spherocytic RBCs to prolong their life span in circulation. These results have significant implications for understanding the clinical heterogeneity of RBC membrane disorders.


Assuntos
Esferócitos/patologia , Esferócitos/fisiologia , Baço/citologia , Baço/fisiologia , Idoso , Deformação Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/patologia , Feminino , Humanos , Técnicas In Vitro , Lisofosfatidilcolinas/farmacologia , Masculino , Pessoa de Meia-Idade , Fragilidade Osmótica/efeitos dos fármacos , Perfusão , Esferócitos/efeitos dos fármacos , Esferocitose Hereditária/sangue , Esferocitose Hereditária/etiologia
17.
Blood ; 119(2): e1-8, 2012 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-22106347

RESUMO

Infection of erythrocytes with the human malaria parasite, Plasmodium falciparum, results in dramatic changes to the host cell structure and morphology. The predicted functional localization of the STEVOR proteins at the erythrocyte surface suggests that they may be involved in parasite-induced modifications of the erythrocyte membrane during parasite development. To address the biologic function of STEVOR proteins, we subjected a panel of stevor transgenic parasites and wild-type clonal lines exhibiting different expression levels for stevor genes to functional assays exploring parasite-induced modifications of the erythrocyte membrane. Using this approach, we show that stevor expression impacts deformability of the erythrocyte membrane. This process may facilitate parasite sequestration in deep tissue vasculature.


Assuntos
Antígenos de Protozoários/metabolismo , Membrana Eritrocítica/patologia , Eritrócitos/patologia , Malária Falciparum/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Antígenos de Protozoários/genética , Células Cultivadas , Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/parasitologia , Eritrócitos/metabolismo , Eritrócitos/parasitologia , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Plasmodium falciparum/isolamento & purificação , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real
18.
Blood ; 119(24): e172-80, 2012 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-22517905

RESUMO

Achievement of malaria elimination requires development of novel strategies interfering with parasite transmission, including targeting the parasite sexual stages (gametocytes). The formation of Plasmodium falciparum gametocytes in the human host takes several days during which immature gametocyte-infected erythrocytes (GIEs) sequester in host tissues. Only mature stage GIEs circulate in the peripheral blood, available to uptake by the Anopheles vector. Mechanisms underlying GIE sequestration and release in circulation are virtually unknown. We show here that mature GIEs are more deformable than immature stages using ektacytometry and microsphiltration methods, and that a switch in cellular deformability in the transition from immature to mature gametocytes is accompanied by the deassociation of parasite-derived STEVOR proteins from the infected erythrocyte membrane. We hypothesize that mechanical retention contributes to sequestration of immature GIEs and that regained deformability of mature gametocytes is associated with their release in the bloodstream and ability to circulate. These processes are proposed to play a key role in P falciparum gametocyte development in the host and to represent novel and unconventional targets for interfering with parasite transmission.


Assuntos
Deformação Eritrocítica/fisiologia , Eritrócitos/parasitologia , Estágios do Ciclo de Vida , Malária Falciparum/sangue , Malária Falciparum/transmissão , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/fisiologia , Adulto , Animais , Antígenos de Protozoários/metabolismo , Imunofluorescência , Humanos , Malária Falciparum/parasitologia , Plasmodium falciparum/ultraestrutura , Transporte Proteico
19.
NPJ Breast Cancer ; 10(1): 6, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38225255

RESUMO

PREDICT Breast ( www.breast .predict.nhs.uk ) is a prognostication tool for early invasive breast cancer. The current version was based on cases diagnosed in 1999-2003 and did not incorporate the benefits of radiotherapy or the harms associated with therapy. Since then, there has been a substantial improvement in the outcomes for breast cancer cases. The aim of this study was to update PREDICT Breast to ensure that the underlying model is appropriate for contemporary patients. Data from the England National Cancer Registration and Advisory Service for invasive breast cancer cases diagnosed 2000-17 were used for model development and validation. Model development was based on 35,474 cases diagnosed and registered by the Eastern Cancer Registry. A Cox model was used to estimate the prognostic effects of the year of diagnosis, age at diagnosis, tumour size, tumour grade and number of positive nodes. Separate models were developed for ER-positive and ER-negative disease. Data on 32,408 cases from the West Midlands Cancer Registry and 100,551 cases from other cancer registries were used for validation. The new model was well-calibrated; predicted breast cancer deaths at 5-, 10- and 15-year were within 10 per cent of the observed validation data. Discrimination was also good: The AUC for 15-year breast cancer survival was 0.809 in the West Midlands data set and 0.846 in the data set for the other registries. The new PREDICT Breast model outperformed the current model and will be implemented in the online tool which should lead to more accurate absolute treatment benefit predictions for individual patients.

20.
Pharmaceuticals (Basel) ; 17(6)2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38931378

RESUMO

Purpose: Acute heart failure (AHF) is associated with high morbidity and mortality, and the prognosis is particularly poor in older patients. Although the application of guideline-directed medical therapy (GDMT) has shown a positive impact on prognosis, the effects are less clear in older age groups. The aim of this study was to analyze real-world data regarding GDMT and outcomes in older HF patients. Methods: This is a prospective cohort study from a secondary care hospital in central Switzerland. A total of 97 consecutive patients aged ≥60 years were enrolled between January 2019 and 2022. The main outcome parameters were prescribed GDMT at discharge, and in case of rehospitalization, GDMT at readmission, and survival in terms of all-cause mortality and HF-related hospitalizations during a 3-year follow-up period. Results: Follow-up data were available for 93/97 patients. The mean age was 77.8 ± 9.8 years, 46% being female. The mean left ventricular ejection fraction (LVEF) was 35.3 ± 13.9%, with a mean BNP level of 2204.3 ± 239 ng/L. Upon discharge, 86% received beta-blockers and 76.3% received renin-angiotensin system (RAS) inhibitors. At rehospitalization for AHF, beta-blockers use was significantly lower and decreased to 52.8% (p = 0.003), whereas RAS inhibitor use increased slightly to 88.9% (p = 0.07), and SGLT-2 inhibitors showed a significant increase from 5.4% vs. 47.2% (p = 0.04). GDMT prescription was not dependent on LVEF. Overall, 73.1% of patients received two-stage or three-stage GDMT at discharge, whereas this percentage decreased to 61% at rehospitalization (p = 0.01). Kaplan-Meier analysis for the combined outcome rehospitalization and death stratified by LV function showed significant differences between LVEF groups (aHR: 0.6 [95% CI: 0.44 to 0.8]; p = 0.0023). Conclusions: Our results indicate that first, the majority of older AHF patients from a secondary care hospital in Switzerland were not on optimal GDMT at discharge and even fewer at readmission, and second, that prognosis of the population is still poor, with almost half of the patients having been rehospitalized or died during a 3-year follow-up period under real-world conditions, without significant difference between women and men. Our findings underline the need for further improvements in the medical treatment of AHF, in particular in older patients, to improve prognosis and to reduce the burden of disease.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA