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1.
Infect Prev Pract ; 6(1): 100335, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38292209

RESUMO

Two SARS-CoV-2 nosocomial outbreaks occurred on the haematology ward of our hospital. Patients on the ward were at high risk for severe infection because of their immunocompromised status. Whole Genome Sequencing proved transmission of a particular SARS-CoV-2 variant in each outbreak. The first outbreak (20 patients/31 healthcare workers (HCW)) occurred in November 2020 and was caused by a variant belonging to lineage B.1.221. At that time, there were still uncertainties on mode of transmission of SARS-CoV-2, and vaccines nor therapy were available. Despite HCW wearing II-R masks in all patient contacts and FFP-2 masks during aerosol generating procedures (AGP), the outbreak continued. Therefore, extra measures were introduced. Firstly, regular PCR-screening of asymptomatic patients and HCW; positive patients were isolated and positive HCW were excluded from work as a rule and they were only allowed to resume their work if a follow-up PCR CT-value was ≥30 and were asymptomatic or having only mild symptoms. Secondly, the use of FFP-2 masks was expanded to some long-lasting, close-contact, non-AGPs. After implementing these measures, the incidence of new cases declined gradually. Thirty-seven percent of patients died due to COVID-19. The second outbreak (10 patients/2 HCW) was caused by the highly transmissible omicron BA.1 variant and occurred in February 2022, where transmission occurred on shared rooms despite the extra infection control measures. It was controlled much faster, and the clinical impact was low as the majority of patients was vaccinated; no patients died and symptoms were relatively mild in both patients and HCW.

2.
Sci Rep ; 11(1): 259, 2021 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-33420252

RESUMO

Chlamydia trachomatis (CT) increases its plasmid numbers when stressed, as occurs in clinical trachoma samples. Most CT tests target the plasmid to increase the test sensitivity, but some only target the chromosome. We investigated clinical urogenital samples for total plasmid copy numbers to assess its diagnostic value and intra-bacterial plasmid copy numbers to assess its natural variation. Both plasmid and chromosome copies were quantified using qPCR, and the plasmid:chromosome ratio (PCr) calculated in two cohorts: (1) 383 urogenital samples for the total PCR (tPCr), and (2) 42 vaginal swabs, with one half treated with propium-monoazide (PMA) to prevent the quantification of extracellular DNA and the other half untreated to allow for both tPCr and intra-bacterial PCr (iPCr) quantification. Mann-Whitney U tests compared PCr between samples, in relation to age and gender. Cohort 1: tPCr varied greatly (1-677, median 16). Median tPCr was significantly higher in urines than vaginal swabs (32 vs. 11, p < 0.001). Cohort 2: iPCr was more stable than tPCr (range 0.1-3 vs. 1-11). To conclude, tPCr in urogenital samples was much more variable than previously described. Transport time and temperature influences DNA degradation, impacting chromosomal DNA more than plasmids and urine more than vaginal samples. Data supports a plasmid target in CT screening assays to increase clinical sensitivity.


Assuntos
Chlamydia trachomatis/genética , Técnicas de Laboratório Clínico/métodos , Doenças Urogenitais Femininas/microbiologia , Dosagem de Genes , Doenças Urogenitais Masculinas/microbiologia , Tracoma/microbiologia , Cromossomos , Feminino , Doenças Urogenitais Femininas/diagnóstico , Humanos , Masculino , Doenças Urogenitais Masculinas/diagnóstico , Plasmídeos/urina , Tracoma/diagnóstico , Urina/microbiologia , Vagina/microbiologia , Adulto Jovem
3.
Anaesthesia ; 76(6): 798-804, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33179248

RESUMO

High-flow nasal oxygen is increasingly used for oxygenation during apnoea. Extending apnoea duration using this technique has mainly been investigated during minor laryngeal surgery, but it is unclear how long it can be administered for before it should be discontinued due to acidosis. We aimed to describe the dynamics of arterial blood gases during apnoeic oxygenation with high-flow nasal oxygen with jaw thrust only, to explore the limits of this technique. We included adult orthopaedic patients scheduled for general anaesthesia. After pre-oxygenation, anaesthesia with neuromuscular blockade was induced and high-flow nasal oxygen (70 l.min-1 ) was continued with jaw thrust as the only means of airway management, with monitoring of vital signs and arterial blood gas sampling every 5 minutes. Apnoeic oxygenation with high-flow nasal oxygen was discontinued when arterial carbon dioxide tension (PaCO2 ) exceeded 12 kPa or pH fell to 7.15. This technique was used in 35 patients and median (IQR [range]) apnoea time was 25 (20-30 [20-45]) min and was discontinued in all patients when pH fell to 7.15. The mean (SD) PaCO2 increase was 0.25 (0.06) kPa.min-1 but it varied substantially (range 0.13-0.35 kPa.min-1 ). Mean (SD) arterial oxygen tension was 48.6 (11.8) kPa when high-flow nasal oxygen was stopped. Patients with apnoea time > 25 minutes were significantly older (p = 0.025). We conclude that apnoeic oxygenation with high-flow nasal oxygen resulted in a significant respiratory acidosis that varies substantially on the individual level, but oxygenation was maintained.


Assuntos
Acidose/prevenção & controle , Apneia/terapia , Oxigenoterapia/métodos , Gasometria/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tempo
4.
Sex Transm Infect ; 95(5): 317-321, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31097678

RESUMO

OBJECTIVES: Most international STI guidelines recommend Chlamydia trachomatis anorectal testing in women after self-reported sexual exposure or symptoms in women. However, it has been shown that the prevalence of anorectal C. trachomatis is as high (7%-17 %) in women who do not report anorectal intercourse (AI) as in women who do. This study assessed the correlation between the genital and anorectal C. trachomatis load in concurrently infected women for increased microbiological insight. METHODS: A convenience sample of 105 women with a concurrent (genital and anorectal) C. trachomatis infection was included from the STI clinic in South Limburg, the Netherlands. Women provided self-collected vaginal and anorectal swabs. The C. trachomatis load was quantified with qPCR and the human cell load was assessed to ensure sample adequacy. Genital and anorectal C. trachomatis loads were divided into tertiles for comparison. The χ2 test and linear regression were used to compare genital and anorectal C. trachomatis loads and identify determinants associated with load. RESULTS: The overall median C. trachomatis load was higher in genital (median 5.3 log10C. trachomatis/ml) than anorectal samples (median 3.4, p ≤ 0.001), but both loads were within the same range. The genital and anal load categories were not related within one woman (p = 0.99), both in women with and without AI. The anorectal C. trachomatis load was in the same or higher load category than the genital load in 56% of women without AI, and 79% of women with AI. CONCLUSIONS: Although no cut-off for clinical relevance is known, an anorectal C. trachomatis load in the same or higher load category than the genital C. trachomatis load is likely to be clinically relevant. Other measurements should also be taken into account, such as leucocytes or bacterial viability to distinguish infection from contamination or exposure.


Assuntos
Infecções por Chlamydia/microbiologia , Chlamydia trachomatis/fisiologia , Vagina/microbiologia , Adolescente , Adulto , Canal Anal/microbiologia , Carga Bacteriana , Chlamydia trachomatis/crescimento & desenvolvimento , Chlamydia trachomatis/isolamento & purificação , Estudos Transversais , Feminino , Humanos , Pessoa de Meia-Idade , Países Baixos , Adulto Jovem
5.
J R Soc Interface ; 15(144)2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30045891

RESUMO

Active tactile exploration behaviour is constrained to a large extent by the morphological and biomechanical properties of the animal's somatosensory system. In the model organism Carausius morosus, the main tactile sensory organs are long, thin, seemingly delicate, but very robust antennae. Previous studies have shown that these antennae are compliant under contact, yet stiff enough to maintain a straight shape during active exploration. Overcritical damping of the flagellum, on the other hand, allows for a rapid return to the straight shape after release of contact. Which roles do the morphological and biomechanical adaptations of the flagellum play in determining these special mechanical properties? To investigate this question, we used a combination of biomechanical experiments and numerical modelling. A set of four finite-element (FE) model variants was derived to investigate the effect of the distinct geometrical and material properties of the flagellum on its static (bending) and dynamic (damping) characteristics. The results of our numerical simulations show that the tapered shape of the flagellum had the strongest influence on its static biomechanical behaviour. The annulated structure and thickness gradient affected the deformability of the flagellum to a lesser degree. The inner endocuticle layer of the flagellum was confirmed to be essential for explaining the strongly damped return behaviour of the antenna. By highlighting the significance of two out of the four main structural features of the insect flagellum, our study provides a basis for mechanical design of biomimetic touch sensors tuned to become maximally flexible while quickly resuming a straight shape after contact.


Assuntos
Antenas de Artrópodes , Modelos Biológicos , Neópteros , Percepção do Tato/fisiologia , Tato/fisiologia , Animais , Antenas de Artrópodes/anatomia & histologia , Antenas de Artrópodes/fisiologia , Neópteros/anatomia & histologia , Neópteros/fisiologia
6.
J R Soc Interface ; 14(132)2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28724628

RESUMO

Insect cuticle is a biological composite with a high degree of complexity in terms of both architecture and material composition. Given the complex morphology of many insect body parts, finite-element (FE) models play an important role in the analysis and interpretation of biomechanical measurements, taken by either macroscopic or nanoscopic techniques. Many previous studies show that the interpretation of nanoindentation measurements of this layered composite material is very challenging. To develop accurate FE models, it is of particular interest to understand more about the variations in the stiffness through the thickness of the cuticle. Considering the difficulties of making direct measurements, in this study, we use the FE method to analyse previously published data and address this issue numerically. For this purpose, sets of continuous or discontinuous stiffness profiles through the thickness of the cuticle were mathematically described. The obtained profiles were assigned to models developed based on the cuticle of three insect species with different geometries and layer configurations. The models were then used to simulate the mechanical behaviour of insect cuticles subjected to nanoindentation experiments. Our results show that FE models with discontinuous exponential stiffness gradients along their thickness were able to predict the stress and deformation states in insect cuticle very well. Our results further suggest that, for more accurate measurements and interpretation of nanoindentation test data, the ratio of the indentation depth to cuticle thickness should be limited to 7% rather than the traditional '10% rule'. The results of this study thus might be useful to provide a deeper insight into the biomechanical consequences of the distinct material distribution in insect cuticle and also to form a basis for more realistic modelling of this complex natural composite.


Assuntos
Insetos/fisiologia , Tegumento Comum/fisiologia , Animais , Fenômenos Biomecânicos , Modelos Biológicos
7.
Biomech Model Mechanobiol ; 16(6): 1947-1955, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28624880

RESUMO

Locust wings are able to sustain millions of cycles of mechanical loading during the lifetime of the insect. Previous studies have shown that cross veins play an important role in delaying crack propagation in the wings. Do cross veins thus also influence the fatigue behaviour of the wings? Since many important fatigue parameters are not experimentally accessible in a small biological sample, here we use the finite element (FE) method to address this question numerically. Our FE model combines a linear elastic material model, a direct cyclic approach and the Paris law and shows results which are in very good agreement with previously reported experimental data. The obtained results of our study show that cross veins indeed enhance the durability of the wings by temporarily stopping cracks. The cross veins further distribute the stress over a larger area and therefore minimize stress concentrations. In addition, our work indicates that locust hind wings have an endurance limit of about 40% of the ultimate tensile strength of the wing material, which is comparable to many engineering materials. The comparison of the results of the computational study with predictions of two most commonly used fatigue failure criteria further indicates that the Goodman criterion can be used to roughly predict the failure of the insect wing. The methodological framework presented in our study could provide a basis for future research on fatigue of insect cuticle and other biological composite structures.


Assuntos
Gafanhotos/fisiologia , Tegumento Comum/fisiopatologia , Fadiga Muscular/fisiologia , Veias/fisiologia , Asas de Animais/irrigação sanguínea , Animais , Fenômenos Biomecânicos , Análise de Elementos Finitos , Estresse Mecânico , Asas de Animais/anatomia & histologia
8.
Nano Lett ; 16(10): 6610-6616, 2016 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-27673379

RESUMO

So far, all previous attempts to apply nanostructures for perfect transmission have not achieved maximum transmittance beyond 99.5% due to the limited regularity of the nanoscale surface geometry: too low for many high-end applications. Here we demonstrate a nanostructured stealth surface, with minimal reflectance (<0.02%) and maximal transmittance (>99.8%) for a wavelength range, covering visible and near-infrared. Compared to multilayer thin film coatings for near-infrared applications our antireflective surfaces operate within a much broader wavelength range, are mechanical stable to resist human touch or contamination, show a 44% higher laser-induced damage threshold, and are suitable for bended interfaces such as microlenses as well.

9.
R Soc Open Sci ; 3(2): 160006, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26998340

RESUMO

Insect wing veins are biological composites of chitin and protein arranged in a complex lamellar configuration. Although these hierarchical structures are found in many 'venous wings' of insects, very little is known about their physical and mechanical characteristics. For the first time, we carried out a systematic comparative study to gain a better understanding of the influence of microstructure on the mechanical characteristics and damping behaviour of the veins. Morphological data have been used to develop a series of three-dimensional numerical models with different material properties and geometries. Finite-element analysis has been employed to simulate the mechanical response of the models under different loading conditions. The modelling strategy used in this study enabled us to determine the effects selectively induced by resilin, friction between layers, shape of the cross section, material composition and layered structure on the stiffness and damping characteristics of wing veins. Numerical simulations suggest that although the presence of the resilin-dominated endocuticle layer results in a much higher flexibility of wing veins, the dumbbell-shaped cross section increases their bending rigidity. Our study further shows that the rubber-like cuticle, friction between layers and material gradient-based design contribute to the higher damping capacity of veins. The results of this study can serve as a reference for the design of novel bioinspired composite structures.

10.
PLoS One ; 10(12): e0145693, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26713628

RESUMO

INTRODUCTION: Although Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection worldwide, little is known about the natural course of the bacterial load during infection. We investigated the natural course of the bacterial load in the interval between screening and returning for treatment in genital and anorectal CT-infections. MATERIALS & METHODS: CT-positive patients, visiting our STI-clinic in the Netherlands from June 2011-January 2014, provided a second urogenital and/or anorectal sample when returning for treatment (diagnostic sample = T1; treatment sample = T2). Patient-record provided data about the days between samples and the date of last unsafe sex. Included patients were ≥18 years old, HIV-negative and did not report antibiotic use in the study-interval. CT load was quantified using qPCR. CT load was log-transformed, and a CT load difference (Δ-CT load) of >1 log was deemed clinically relevant. Chi-square test compared load category distributions over time (decrease/equal/increase), between sample types. RESULTS: 274 patients provided 296 paired samples. Majority of samples had a stable CT load in the interval T1-T2 (66.3%, 73.1% and 48.6% for vaginal swabs, urine and anorectal swabs resp. p = 0.07). Load decreased in 17-41% of patients, while ±10% of patients showed an increase in CT load. No association between Δ-CT load and the interval T1-T2 was observed. Large variations can be seen in CT load at T1 and over time. DISCUSSION: The majority (±90%) of patients have a stable or decreasing CT load in the time interval between screening and returning for treatment. The number of days between sampling was not associated with change in CT load. In the first month after the last unsafe sex, only stable CT loads were seen. Our data seems to indicate that when most patients visit an STI-clinic, recommended 2 weeks after infection, the infection has already been established or is in its downward phase.


Assuntos
Canal Anal/microbiologia , Carga Bacteriana , Infecções por Chlamydia/diagnóstico , Infecções por Chlamydia/terapia , Chlamydia trachomatis/fisiologia , Genitália Feminina/microbiologia , Reto/microbiologia , Adolescente , Adulto , Infecções por Chlamydia/microbiologia , Progressão da Doença , Feminino , Humanos , Pessoa de Meia-Idade , Sexo sem Proteção , Adulto Jovem
11.
Transpl Infect Dis ; 17(5): 751-5, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26432076

RESUMO

Multidrug-resistant (MDR) cytomegalovirus (CMV) emerged after transient responses to ganciclovir, foscarnet, and cidofovir in a CMV-seropositive recipient who underwent allogeneic hematopoietic stem cell transplantation from a CMV-seronegative donor. Experimental treatments using leflunomide and artesunate failed. Re-transplantation from a CMV-seropositive donor supported by adoptive transfer of pp65-specific T cells and maribavir was followed by lasting suppression. This case illustrates that successful MDR CMV therapy may require individualized multidisciplinary approaches.


Assuntos
Infecções por Citomegalovirus/terapia , Farmacorresistência Viral Múltipla , Transplante de Células-Tronco Hematopoéticas , Hospedeiro Imunocomprometido , Transferência Adotiva , Antivirais/uso terapêutico , Terapia Combinada , Infecções por Citomegalovirus/imunologia , Quimioterapia Combinada , Humanos , Masculino , Pessoa de Meia-Idade
12.
Bioinspir Biomim ; 10(5): 056003, 2015 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-26292260

RESUMO

The flight performance of insects is strongly affected by the deformation of the wing during a stroke cycle. Many insects therefore use both active and passive mechanisms to control the deformation of their wings in flight. Several studies have focused on the wing kinematics, and plenty is known about the mechanism of their passive deformability. However, given the small size of the vein-joints, accurate direct mechanical experiments are almost impossible to perform. We therefore developed numerical models to perform a comparative and comprehensive investigation of the mechanical behaviour of the vein-joints under external loading conditions. The results illustrate the effect of the geometry and the presence of the rubberlike protein resilin on the flexibility of the joints. Our simulations further show the contribution of the spikes to the anisotropic flexural stiffness in the dorsal and ventral directions. In addition, our results show that the cross veins, only in one joint type, help to transfer the stress to the thicker longitudinal veins. The deformation pattern and the stress distribution in each vein-joint are discussed in detail. This study provides a strong background for further realistic modelling of the dragonfly wing deformation.


Assuntos
Voo Animal/fisiologia , Insetos/fisiologia , Articulações/fisiologia , Modelos Biológicos , Asas de Animais/fisiologia , Animais , Simulação por Computador , Módulo de Elasticidade , Resistência ao Cisalhamento/fisiologia , Estresse Mecânico , Resistência à Tração/fisiologia
13.
J Biomech ; 48(1): 89-94, 2015 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-25468669

RESUMO

The wings of insects are extremely light-weight biological composites with exceptional biomechanical properties. In the recent years, numerical simulations have become a very powerful tool to answer experimentally inaccessible questions on the biomechanics of insect flight. However, many of the presented models require a sophisticated balance of biomechanical material parameters, many of which are not yet available. In this article we show the first numerical simulations of crack propagation in insect wings. We have used a combination of the maximum-principal stress theory, the traction separation law and basic biomechanical properties of cuticle to develop simple yet accurate finite element (FE) models of locust wings. The numerical results of simulated tensile tests on wing samples are in very good qualitative, and interestingly, also in excellent quantitative agreement with previously obtained experimental data. Our study further supports the idea that the cross-veins in insect wings act as barriers against crack propagation and consequently play a dominant role in toughening the whole wing structure. The use of numerical simulations also allowed us to combine experimental data with previously inaccessible data, such as the distribution of the first principal stress through the wing membrane and the veins. A closer look at the stress-distribution within the wings might help to better understand fracture-toughening mechanisms and also to design more durable biomimetic micro-air vehicles.


Assuntos
Gafanhotos/fisiologia , Modelos Teóricos , Asas de Animais/fisiologia , Animais , Fenômenos Biomecânicos , Biomimética , Feminino , Análise de Elementos Finitos , Voo Animal , Gafanhotos/anatomia & histologia , Insetos , Asas de Animais/anatomia & histologia
14.
Am J Transplant ; 14(9): 2159-67, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25040687

RESUMO

Cell-mediated immunity assays could be valuable for risk assessment of organ donors, but no data exist on their feasibility in deceased donors. In this study, 105 deceased donors (52.3 ± 16.9 years) were screened at the time of organ procurement. Pathogen-specific stimulation was performed using a cytomegalovirus (CMV) lysate, tuberculin (purified protein derivative [PPD]) and soluble Mycobacterium tuberculosis-specific ESAT-6/CFP-10 proteins in combination with an in-house fluorescence-activated cell sorting (FACS) assay or commercial assay formats (QuantiFERON-CMV/TB for ELISA, T-SPOT.TB for ELISPOT). CMV-IgG antibody titers were determined as gold standard for CMV infection; 51.4% of samples were CMV seropositive. Indeterminate results were observed in 47.6% of ELISA, 12.5% of FACS and 0% of ELISPOT assays. Agreement with serology was highest for FACS (95.6%, κ = 0.91), followed by ELISPOT (84.0%, κ = 0.68) and ELISA (80.0%, κ = 0.60). Agreement between ELISA and serology increased if the CMV lysate was used as stimulus (96.7%, κ = 0.92). Among the T cell assays, agreement between ELISPOT and FACS was highest (κ = 0.70). PPD-positive results among valid samples differed between assays (26.5% for ELISA, 23.1% for FACS and 50.5% for ELISPOT); 2.0% were QuantiFERON-TB positive, 3.3% were ESAT-6/CFP-10-positive in FACS and 13.4% were positive in the T-SPOT.TB assay. In conclusion, cellular immunity may be analyzed from samples of deceased donors, although the assays differ in the rate of positivity and indeterminate results.


Assuntos
Cadáver , Citomegalovirus/imunologia , Imunidade Celular , Mycobacterium tuberculosis/imunologia , Doadores de Tecidos , Adulto , Idoso , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
15.
Am J Transplant ; 14(6): 1334-45, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24726000

RESUMO

BK polyomavirus (BKPyV) infection is widespread and typically asymptomatic during childhood, but may cause nephropathy in kidney transplant recipients. However, there is only limited knowledge on BKPyV-specific immunity in children and adults, and its role in BKPyV-replication and disease posttransplant. We therefore characterized BKPyV-specific immunity from 122 immunocompetent individuals (1-84 years), 38 adult kidney recipients with (n = 14) and without BKPyV-associated complications (n = 24), and 25 hemodialysis (HD) patients. Blood samples were stimulated with overlapping peptides of BKPyV large-T antigen and VP1 followed by flow-cytometric analysis of activated CD4 T cells expressing interferon-γ, IL-2 and tumor necrosis factor-α. Antibody-levels were determined using enzyme-linked immunosorbent assay. Both BKPyV-IgG levels and BKPyV-specific CD4 T cell frequencies were age-dependent (p = 0.0059) with maximum levels between 20 and 30 years (0.042%, interquartile range 0.05%). Transplant recipients showed a significantly higher BKPyV-specific T cell prevalence (57.9%) compared to age-matched controls (21.7%) or HD patients (28%, p = 0.017). Clinically relevant BKPyV-replication was associated with elevated frequencies of BKPyV-specific T cells (p = 0.0002), but decreased percentage of cells expressing multiple cytokines (p = 0.009). In conclusion, BKPyV-specific cellular immunity reflects phases of active BKPyV-replication either after primary infection in childhood or during reactivation after transplantation. Combined analysis of BKPyV-specific T cell functionality and viral loads may improve individual risk assessment.


Assuntos
Vírus BK/imunologia , Linfócitos T CD4-Positivos/imunologia , Replicação Viral , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Vírus BK/fisiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Adulto Jovem
16.
Am J Transplant ; 13(12): 3132-41, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24148296

RESUMO

Expression of the inhibitory receptor programmed death 1 (PD-1) on cytomegalovirus (CMV)-specific CD4 T cells defines a phenotype associated with CMV viremia in transplant recipients. Moreover, CD28(-) CD27(-) double negativity is known as a typical phenotype of CMV-specific CD4 T cells. Therefore, the co-expression of inhibitory receptors on CD28(-) CD27(-) CD4 T cells was assessed as a rapid, stimulation-independent parameter for monitoring CMV complications after transplantation. Ninety-three controls, 67 hemodialysis patients and 81 renal transplant recipients were recruited in a cross-sectional and longitudinal manner. CMV-specific CD4 T cell levels quantified after stimulation were compared to levels of CD28(-) CD27(-) CD4 T cells. PD-1 and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) expression on CD28(-) CD27(-) CD4 T cells were related to viremia. A percentage of ≥0.44% CD28(-) CD27(-) CD4 T cells defined CMV seropositivity (93.3% sensitivity, 97.1% specificity), and their frequencies correlated strongly with CMV-specific CD4 T cell levels after stimulation (r = 0.73, p < 0.0001). Highest PD-1 expression levels on CD28(-) CD27(-) CD4 T cells were observed in patients with primary CMV viremia and reactivation (p < 0.0001), whereas CTLA-4 expression was only elevated during primary CMV viremia (p < 0.05). Longitudinal analysis showed a significant increase in PD-1 expression in relation to viremia (p < 0.001), whereas changes in nonviremic patients were nonsignificant. In conclusion, increased PD-1 expression on CD28(-) CD27(-) CD4 T cells correlates with CMV viremia in transplant recipients and may serve as a specific, stimulation-independent parameter to guide duration of antiviral therapy.


Assuntos
Antígenos CD28/metabolismo , Linfócitos T CD4-Positivos/citologia , Infecções por Citomegalovirus/complicações , Receptor de Morte Celular Programada 1/metabolismo , Insuficiência Renal/sangue , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/metabolismo , Viremia/complicações , Adulto , Antivirais/química , Estudos de Casos e Controles , Estudos Transversais , Citomegalovirus , Citometria de Fluxo , Humanos , Transplante de Rim , Pessoa de Meia-Idade , Fenótipo , Complicações Pós-Operatórias , Diálise Renal , Insuficiência Renal/complicações , Insuficiência Renal/terapia , Sensibilidade e Especificidade
17.
Transpl Infect Dis ; 15(1): 79-89, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23176118

RESUMO

BACKGROUND: Programmed death receptor-1 (PD-1) compromises cytomegalovirus (CMV)-specific T-cell responses and has been linked to CMV viremia after transplantation. An impaired functional and proliferative capacity of PD-1-positive CMV-specific T cells may be reversed by the antibody-mediated blockade of PD-1 signaling. However, knowledge is limited on changes in "cytokinome" expression profiles associated with reversal of functional exhaustion. METHODS: The "cytokinome" was analyzed by 27-plex Luminex technology comparing renal transplant recipients with low (n = 5) and high (n = 5) PD-1 expression on CMV-specific T cells. The effect of blocking PD-1 by PD-ligand (PD-L) antibodies on restoration of cytokine expression was examined. RESULTS: CMV-specific cytokine release and proliferation was lower in patients with high PD-1 expression on CMV-specific T cells. Antibody-mediated blockade of PD-L in CMV-stimulated samples restored expression levels of interleukin (IL)-1ß, IL-2, IL-6, IL-9, IL-10, granulocyte colony-stimulating factor, interferon-γ, macrophage inflammatory protein-1α, and tumor necrosis factor-α. By contrast, no profound effect was observed for controls or patients with low PD-1 expression, or in staphylococcal enterotoxin B-stimulated cells. CONCLUSION: Taken together, this pilot study provides evidence that a high PD-1 expression on CMV-specific T cells actively impairs proliferation and "cytokinome" responses in an antigen-specific manner. Importantly, blockade of PD-L restores CMV-specific T-cell proliferation and expression of a panel of different proinflammatory and/or type 1 cytokines, suggesting a common but as yet unknown regulatory principle. We conclude that PD-1 exhaustion is reversible and potentially amenable to therapeutic ex vivo and possibly in vivo manipulation. However, detailed knowledge of the differential effects on the "cytokinome" will be necessary to increase the safety and the efficacy of such manipulations.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Citocinas/metabolismo , Infecções por Citomegalovirus/imunologia , Citomegalovirus/imunologia , Transplante de Rim , Receptor de Morte Celular Programada 1/imunologia , Adulto , Idoso , Anticorpos Bloqueadores/uso terapêutico , Estudos Transversais , Infecções por Citomegalovirus/prevenção & controle , Feminino , Humanos , Imunossupressores/uso terapêutico , Ativação Linfocitária/imunologia , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Proteína 2 Ligante de Morte Celular Programada 1/imunologia , Viremia/imunologia
18.
Am J Transplant ; 8(7): 1486-97, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18510628

RESUMO

Cytomegalovirus (CMV) represents a major cause of infectious complications after transplantation. Recently, chronic infections with lymphocyte choriomeningitis virus (LCMV), HIV or HCV were shown to be associated with functionally exhausted T cells characterized by high expression of the programmed death (PD)-1 molecule and altered cytokine expression patterns. We therefore hypothesized that functional exhaustion of CMV-specific CD4 T cells may determine impaired CMV control in patients after renal transplantation. In viremic transplant recipients, a significantly higher proportion of CMV-specific CD4 T cells was PD-1 positive (median 40.9%, 17.0-88.7%) as compared to nonviremic transplant patients (8.8%, 0.8-80.5%), dialysis patients (8.8%, 0-36.7%) or controls (3.2%, 0.3-15.4%, p < 0.0001). In line with functional impairment, PD-1-positive T cells produced significantly less IFNgamma as compared to PD-1-negative T cells (p < 0.0001). Moreover, unlike controls or nonviremic patients, CMV-specific T cells from viremic patients showed a significant loss of IL-2 production (p < 0.0001). Interestingly, functional anergy of CMV-specific CD4 T cells was reversible in that antibody-mediated blockade of PD-1 signaling with its ligands PD-L1/-L2 led to an up to 10-fold increase in CMV-specific proliferation. In conclusion, expression of PD-1 defines a reversible defect of CMV-specific CD4 T cells that is associated with viremia, and blocking PD-1 signaling may provide a potential target for enhancing the function of exhausted T cells in chronic CMV infection.


Assuntos
Antígenos CD/biossíntese , Proteínas Reguladoras de Apoptose/biossíntese , Linfócitos T CD4-Positivos/metabolismo , Infecções por Citomegalovirus/metabolismo , Interleucina-2/biossíntese , Transplante de Rim , Adulto , Idoso , Linfócitos T CD4-Positivos/virologia , Estudos de Casos e Controles , Anergia Clonal , Citomegalovirus/metabolismo , Infecções por Citomegalovirus/virologia , Feminino , Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Receptor de Morte Celular Programada 1 , Carga Viral , Viremia/metabolismo , Replicação Viral
19.
Kidney Int ; 70(8): 1397-402, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16955109

RESUMO

Representatives from five international organizations (International Society of Nephrology, World Heart Federation, International Diabetes Federation, International Atherosclerosis Federation, and International Society of Hypertension) participated in a strategic planning workshop in December 2005 in Bellagio, Italy sponsored by the Rockefeller Foundation. There were equal representatives from developed and developing countries. Global perspectives on diabetes and cardiovascular and renal diseases were presented, with special emphasis on China, India, Latin America, and Africa. The rationale and effectiveness of preventive measures were discussed. It was apparent that measures for primary prevention and early intervention for all the chronic vascular diseases are similar. The five organizations agreed that an integrated global approach to chronic vascular diseases is needed. They resolved to collaborate and work towards an integrated approach to chronic vascular diseases with the establishment of a 5-year plan for the prevention and treatment of chronic vascular diseases, including public advocacy, advising international and national agencies, and improving education and the practice of established approaches.


Assuntos
Complicações do Diabetes/prevenção & controle , Saúde Global , Agências Internacionais/tendências , Doenças Vasculares/prevenção & controle , Doença Crônica , Países Desenvolvidos , Países em Desenvolvimento , Diabetes Mellitus/prevenção & controle , Acessibilidade aos Serviços de Saúde , Humanos , Cooperação Internacional , Itália , Nefropatias/prevenção & controle , Defesa do Paciente , Fatores de Risco
20.
Kidney Int ; 70(6): 982-4, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16957745

RESUMO

Dialysis rationing resulting from limited facilities and health-care personnel in low- and middle-income countries such as South Africa must be addressed on several fronts. Prevention of kidney disease is an essential long-term approach, but in the short term, it is necessary to increase access to dialysis and transplantation, and to seek ways to limit the 'brain drain' to the developed world.


Assuntos
Alocação de Recursos para a Atenção à Saúde/economia , Alocação de Recursos para a Atenção à Saúde/tendências , Falência Renal Crônica/terapia , Diálise Renal , Tomada de Decisões , Países em Desenvolvimento/economia , Alocação de Recursos para a Atenção à Saúde/estatística & dados numéricos , Humanos , Falência Renal Crônica/economia , Falência Renal Crônica/epidemiologia , Transplante de Rim/estatística & dados numéricos , Diálise Renal/economia , Diálise Renal/métodos , Diálise Renal/estatística & dados numéricos , Estudos Retrospectivos , Fatores Socioeconômicos , África do Sul/epidemiologia
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