Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 185
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Ultrasound Obstet Gynecol ; 59(6): 763-770, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-34931725

RESUMO

OBJECTIVES: To evaluate the short- and long-term outcome of late-preterm compared with term birth in twin pregnancy. METHODS: This retrospective observational cohort study included all women who had a twin delivery between 1 January 2007 and 31 December 2010 recorded in the claims database of the Korea National Health Insurance, with at least one follow-up recorded in the database of the National Health Screening Program for Infants and Children. Outcomes were analyzed at the pregnancy level, with adverse outcome being defined as an adverse outcome in one or both twins, identified by a diagnosis according to the International Classification of Diseases 10th Revision. The primary short-term outcome was composite morbidity, which included any of the following: transient tachypnea, respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage and bronchopulmonary dysplasia. Long-term adverse outcome included any neurological or neurodevelopmental outcome, defined by prespecified neurological and developmental diagnoses; these were assessed by following up all neonates until the end of 2018, by which time they were 8-11 years of age. Outcomes were compared between twins delivered late preterm (34 + 0 to 36 + 6 weeks) and those delivered at term (≥ 37 weeks). RESULTS: Among 17 189 women who delivered twins at ≥ 34 weeks of gestation during the study period, 5032 (29.27%) women delivered in the late-preterm period. On multivariate analysis, compared with the twins delivered at term, the late-preterm twins had an increased risk for the primary short-term outcome of composite morbidity (adjusted odds ratio (aOR), 2.09; 95% CI, 1.90-2.30), including transient tachypnea (aOR, 1.85; 95% CI, 1.64-2.09), respiratory distress syndrome (aOR, 2.31; 95% CI, 2.04-2.62), necrotizing enterocolitis (aOR, 2.10; 95% CI, 1.20-3.69) and intraventricular hemorrhage (aOR, 2.13; 95% CI, 1.46-3.11). For the long-term outcome, the late-preterm twins also had an increased risk for any neurological or neurodevelopmental outcome (adjusted hazard ratio, 1.14; 95% CI, 1.07-1.21). CONCLUSIONS: Twins delivered in the late-preterm period have an increased risk for short- and long-term morbidity compared with twins delivered at term. These results should be considered when determining the timing of delivery in uncomplicated twin pregnancy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.


Assuntos
Enterocolite Necrosante , Doenças do Recém-Nascido , Nascimento Prematuro , Síndrome do Desconforto Respiratório do Recém-Nascido , Criança , Feminino , Hemorragia , Humanos , Lactente , Recém-Nascido , Masculino , Gravidez , Nascimento Prematuro/epidemiologia , Síndrome do Desconforto Respiratório do Recém-Nascido/epidemiologia , Estudos Retrospectivos , Taquipneia
2.
BJOG ; 128(4): 738-744, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32946626

RESUMO

OBJECTIVE: To determine whether postpartum haemorrhage (PPH) is associated with cardiovascular disease (CVD), including cerebrovascular and ischaemic heart disease beyond the peripartum period. DESIGN: Population-based cohort study. SETTING: Merged databases of the Korea National Health Insurance (KNHI) claims, National Health Screening Examination and National Health Screening Program for Infants and Children. POPULATION: Women who gave birth in 2007 in the Republic of Korea and who were tracked through to 2015 for the occurrence of CVD. METHODS: Patients were identified and the occurrences of PPH and transfusion were determined using the KNHI claims database. The occurrence of CVD was tracked through 2015 using codes from the International Classification of Diseases, tenth revision (ICD-10). MAIN OUTCOME MEASURES: The risk of CVD after PPH. RESULTS: Among 150 381 women who gave birth during the study period, 9107 were diagnosed with PPH and 899 were treated with transfusion. The risk of CVD in women with PPH was no different than in women without PPH, after adjustment (HR 1.03, 95% CI 0.93-1.13). The risk of CVD in women with PPH requiring transfusion was significantly increased compared with women without PPH, after adjustment (HR 1.60, 95% CI 1.25-2.06). The risk of CVD in women with PPH without transfusion was not significantly different compared with women without PPH (HR 0.96, 95% CI 0.86-1.07). CONCLUSIONS: Postpartum haemorrhage (PPH) requiring transfusion is associated with an increased risk of CVD. Guidelines for management should be established, and further studies on the mechanisms involved should be conducted. TWEETABLE ABSTRACT: PPH requiring transfusion is associated with an increased risk of CVD.


Assuntos
Transfusão de Sangue , Doenças Cardiovasculares/etiologia , Hemorragia Pós-Parto/terapia , Adulto , Doenças Cardiovasculares/epidemiologia , Bases de Dados Factuais , Feminino , Seguimentos , Humanos , Incidência , Estimativa de Kaplan-Meier , Pessoa de Meia-Idade , Gravidez , Modelos de Riscos Proporcionais , República da Coreia/epidemiologia , Estudos Retrospectivos , Fatores de Risco
3.
Br J Surg ; 107(11): 1429-1439, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32492186

RESUMO

BACKGROUND: Sentinel node navigation surgery reduces the extent of gastric and lymph node dissection, and may improve quality of life. The benefit and harm of laparoscopic sentinel node navigation surgery (LSNNS) for early gastric cancer is unknown. The SENORITA (SEntinel Node ORIented Tailored Approach) trial investigated the pathological and surgical outcomes of LSNNS compared with laparoscopic standard gastrectomy (LSG) with lymph node dissection. METHODS: The SENORITA trial was an investigator-initiated, open-label, parallel-assigned, non-inferiority, multicentre RCT conducted in Korea. The primary endpoint was 3-year disease-free survival. The secondary endpoints, morbidity and mortality within 30 days of surgery, are reported in the present study. RESULTS: A total of 580 patients were randomized to LSG (292) or LSNNS (288). Surgery was undertaken in 527 patients (LSG 269, LSNNS 258). LSNNS could be performed according to the protocol in 245 of 258 patients, and a sentinel node basin was detected in 237 (96·7 per cent) Stomach-preserving surgery was carried out in 210 of 258 patients (81·4 per cent). Postoperative complications occurred in 51 patients in the LSG group (19·0 per cent) and 40 (15·5 per cent) in the LSNNS group (P = 0·294). Complications with a Clavien-Dindo grade of III or higher occurred in 16 (5·9 per cent) and 13 (5·0 per cent) patients in the LSG and LSNNS groups respectively (P = 0·647). CONCLUSION: The rate and severity of complications following LSNNS for early gastric cancer are comparable to those after LSG with lymph node dissection. Registration number: NCT01804998 ( http://www.clinicaltrials.gov).


ANTECEDENTES: La cirugía de navegación del ganglio centinela (sentinel node navigation surgery, SNNS) reduce la extensión de la resección gástrica y ganglionar, y puede mejorar la calidad de vida. Se desconoce el beneficio y el daño de la cirugía de navegación del ganglio centinela por vía laparoscópica (laparoscopic sentinel node navigation surgery, LSNNS) para el cáncer gástrico precoz. El ensayo clínico SENORITA investigó los resultados patológicos y quirúrgicos de LSNNS en comparación con la gastrectomía laparoscópica estándar (laparoscopic gastrectomy, LSG) con disección ganglionar (lymph node dissection, LND). MÉTODOS: El ensayo SENORITA fue un ensayo multicéntrico aleatorizado y controlado, iniciado por investigadores, abierto, con asignación a grupos paralelos y de no inferioridad llevado a cabo en Corea. El resultado primario fue la supervivencia libre de enfermedad a los 3 años. En el presente estudio, se describen los resultados secundarios correspondientes a morbilidad y mortalidad a los 30 días del postoperatorio. RESULTADOS: Un total de 580 pacientes fueron aleatorizados a LG (n = 292) o LSNNS (n = 288). La cirugía se realizó en 527 pacientes (LG 269, LSNNS 258). LSNNS pudo ser realizada de acuerdo con el protocolo en 245 de 258 pacientes y en 237 de 245 pacientes (96,7%) se detectó un ganglio centinela. La cirugía con preservación del estómago se realizó en 210 de 258 pacientes (81,4%). Las complicaciones postoperatorias se presentaron en 51 pacientes del grupo LSG (19,0%) y en 40 pacientes (15,5%) del grupo LSNNS (P = 0,294). Las complicaciones grado III o mayor de Clavien-Dindo se detectaron en 16 (5,9%) y 13 pacientes (5,0%) de los grupos LSG y LSNNS, respectivamente (P = 0,647). CONCLUSIÓN: El porcentaje y la gravedad de las complicaciones tras LSNNS para cancer gástrico precoz son comparables a la LSG con LND.


Assuntos
Adenocarcinoma/cirurgia , Gastrectomia/métodos , Laparoscopia/métodos , Excisão de Linfonodo/métodos , Linfonodo Sentinela/cirurgia , Neoplasias Gástricas/cirurgia , Adenocarcinoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Análise de Intenção de Tratamento , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Complicações Pós-Operatórias/epidemiologia , Linfonodo Sentinela/patologia , Neoplasias Gástricas/patologia , Resultado do Tratamento
4.
BJOG ; 127(13): 1646-1654, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32536019

RESUMO

OBJECTIVE: To compare the efficacy of two types of progestogen therapy for preventing preterm birth (PTB) and to review the relevant literature. DESIGN: A multicentre, randomised, open-label, equivalence trial and a meta-analysis. SETTING: Tertiary referral hospitals in South Korea. POPULATION: Pregnant women with a history of spontaneous PTB or short cervical length (<25 mm). METHODS: Eligible women were screened and randomised at 16-22 weeks of gestation to receive either 200 mg of vaginal micronised progesterone daily (vaginal group) or an intramuscular injection of 250 mg 17α-hydroxyprogesterone caproate weekly (IM group). Stratified randomisation was carried out according to participating centres and indications for progestogen therapy. This trial was registered at ClinicalTrials.gov (NCT02304237). MAIN OUTCOME MEASURE: Preterm birth (PTB) before 37 weeks of gestation. RESULTS: A total of 266 women were randomly assigned and a total of 247 women (119 and 128 women in the vaginal and IM groups, respectively) were available for the intention-to-treat analysis. Risks of PTB before 37 weeks of gestation did not significantly differ between the two groups (22.7 versus 25.8%, P = 0.571). The difference in PTB risk between the two groups was 3.1% (95% CI -7.6 to 13.8%), which was within the equivalence margin of 15%. The meta-analysis results showed no significant differences in the risk of PTB between the vaginal and IM progestogen treatments. CONCLUSION: Compared with vaginal progesterone, treatment with intramuscular progestin might increase the risk of PTB before 37 weeks of gestation by as much as 13.8%, or reduce the risk by as much as 7.6%, in women with a history of spontaneous PTB or with short cervical length. TWEETABLE ABSTRACT: Vaginal and intramuscular progestogen showed equivalent efficacy for preventing preterm birth before 37 weeks of gestation.


Assuntos
Nascimento Prematuro/prevenção & controle , Progestinas/administração & dosagem , Administração Intravaginal , Adulto , Feminino , Humanos , Injeções Intramusculares , Metanálise como Assunto , Gravidez , Gravidez de Alto Risco
5.
Bull Entomol Res ; 110(4): 521-534, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32037992

RESUMO

Pear psyllids (Hemiptera: Psylloidea: Psyllidae: Cacopsylla spp.) belong to the most serious pests of pear (Pyrus spp.). They damage pear trees by excessive removal of phloem sap, by soiling the fruits with honeydew which, in turn, provides a substrate for sooty mould, and by transmission of Candidatus Phytoplasma spp., the causal agents of the pear decline disease. The morphological similarity, the presence of seasonal dimorphism that affects adult colour, size and wing morphology and uncritical use of species names, led to much confusion in the taxonomy of pear psyllids. As a result, pear psyllids have been frequently misidentified. Many of the entries attributed to Cacopsylla pyricola and other species in the GenBank are misidentifications which led to additional, unnecessary confusion. Here we analysed DNA barcodes of 11 pear psyllid species from eastern Asia, Europe and Iran using four mitochondrial gene fragments (COI 658 bp, COI 403 bp, COI-tRNAleu-COII 580 bp and 16S rDNA 452 bp). The efficiency of identification was notably high and considerable barcoding gaps were observed in all markers. Our results confirm the synonymies of the seasonal forms of Cacopsylla jukyungi ( = C. cinereosignata, winter form) and C. maculatili ( = C. qiuzili, summer form) previously suggested based on morphology. Some previous misidentifications (C. chinensis from China, Japan and Korea = misidentification of C. jukyungi; C. pyricola and C. pyrisuga from East Asia = misidentification of C. jukyungi and C. burckhardti, respectively; C. pyricola from Iran = misidentification of C. bidens, C. pyri and Cacopsylla sp.) are also corrected. There is no evidence for the presence of European pear psyllid species in East Asia.


Assuntos
Hemípteros/química , Hemípteros/genética , Animais , Código de Barras de DNA Taxonômico/métodos , Genes de Insetos , Genes Mitocondriais , Especificidade da Espécie
6.
BJOG ; 126(7): 901-905, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30758126

RESUMO

OBJECTIVES: To evaluate the association of a history of threatened preterm labour (TPL) followed by term delivery with the risk of spontaneous preterm delivery (PTD) in subsequent pregnancy. DESIGN: Population-based cohort study. SETTING: Data of the National Health Insurance Claims Database and a national health-screening programme for infants and children in South Korea. POPULATION: Women who had their first singleton delivery in 2010 and a subsequent second singleton delivery between 2011 and 2015. METHODS: Multivariable analysis adjusting for maternal age and interval between first and second deliveries was used to assess the risk of PTD based on PTD, TPL followed by term delivery, and term delivery in the first pregnancy. MAIN OUTCOME MEASURES: The risk of PTD during the second pregnancy. RESULTS: This study included 115 629 women with two consecutive deliveries during the study period. Spontaneous PTD rates in the second pregnancy were 7.71, 2.22 and 1.02% in women with PTD, TPL followed by term delivery, and term delivery in the first pregnancy, respectively. Threatened preterm labour followed by term delivery in the first pregnancy was associated with increased risk of PTD in the subsequent pregnancy after adjustment for potential confounding factors (adjusted odds ratio 2.21; 95% CI 1.76-2.78). CONCLUSION: Although women with a history of TPL followed by term delivery had a lower risk of PTD during a subsequent pregnancy compared with those with history of previous PTD, they still had a significantly increased risk of PTD compared with those who delivered at term without TPL. TWEETABLE ABSTRACT: The history of threatened preterm labour followed by term delivery is related to increased risk of subsequent spontaneous preterm delivery.


Assuntos
Ameaça de Aborto/epidemiologia , Nascimento Prematuro/epidemiologia , Nascimento a Termo/fisiologia , Adulto , Estudos de Coortes , Feminino , Humanos , Idade Materna , Gravidez , Recidiva , República da Coreia/epidemiologia , Fatores de Risco
7.
Transfus Med ; 29(1): 16-19, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30859641

RESUMO

The third European Conference on Donor Health and Management (ECDHM) was held in Copenhagen from 5th to 7th September 2018 and was co-organised by the ECDHM committees and European Blood Alliance. This is an international conference with a focus on 'donor health', including donors of blood, organs and other substances of human origin, and remains the only conference focusing exclusively on donor medicine. This overview presents a selection of research topics in relation to iron, the keynote speeches and plenary talks. The keynote speeches cover the epidemiology of donors and recipients, whole-blood donor recruitment and retention and the safety of donors and recipients of plasma and plasma products. Talks from the plenary speakers reviewed modern multi-omic approaches to study red cell quality and the central, perennial question of what motivates a donor to give blood and how can this be encouraged.


Assuntos
Doadores de Sangue , Seleção do Doador , Congressos como Assunto , Europa (Continente) , Humanos
8.
Transfus Med ; 29 Suppl 1: 42-51, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29767450

RESUMO

OBJECTIVES: To evaluate the cost-effectiveness of changing opening times, introducing a donor health report and reducing the minimum inter-donation interval for donors attending static centres. BACKGROUND: Evidence is required about the effect of changes to the blood collection service on costs and the frequency of donation. METHODS/MATERIALS: This study estimated the effect of changes to the blood collection service in England on the annual number of whole-blood donations by current donors. We used donors' responses to a stated preference survey, donor registry data on donation frequency and deferral rates from the INTERVAL trial. Costs measured were those anticipated to differ between strategies. We reported the cost per additional unit of blood collected for each strategy versus current practice. Strategies with a cost per additional unit of whole blood less than £30 (an estimate of the current cost of collection) were judged likely to be cost-effective. RESULTS: In static donor centres, extending opening times to evenings and weekends provided an additional unit of whole blood at a cost of £23 and £29, respectively. Introducing a health report cost £130 per additional unit of blood collected. Although the strategy of reducing the minimum inter-donation interval had the lowest cost per additional unit of blood collected (£10), this increased the rate of deferrals due to low haemoglobin (Hb). CONCLUSION: The introduction of a donor health report is unlikely to provide a sufficient increase in donation frequency to justify the additional costs. A more cost-effective change is to extend opening hours for blood collection at static centres.


Assuntos
Doadores de Sangue , Seleção do Doador/economia , Adolescente , Adulto , Análise Custo-Benefício , Inglaterra , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
9.
Magn Reson Med ; 80(5): 1949-1961, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29656389

RESUMO

PURPOSE: To evaluate the robustness of MR transverse relaxation times of trabecular bone from spin-echo and gradient-echo acquisitions at multiple spatial resolutions of 7 T. METHODS: The effects of MRI resolutions to T2 and T2* of trabecular bone were numerically evaluated by Monte Carlo simulations. T2 , T2*, and trabecular structural indices from multislice multi-echo and UTE acquisitions were measured in defatted human distal femoral condyles on a 7 T scanner. Reference structural indices were extracted from high-resolution microcomputed tomography images. For bovine knee trabecular samples with intact bone marrow, T2 and T2* were measured by degrading spatial resolutions on a 7 T system. RESULTS: In the defatted trabecular experiment, both T2 and T2* values showed strong ( |r| > 0.80) correlations with trabecular spacing and number, at a high spatial resolution of 125 µm3 . The correlations for MR image-segmentation-derived structural indices were significantly degraded ( |r| < 0.50) at spatial resolutions of 250 and 500 µm3 . The correlations for T2* rapidly dropped ( |r| < 0.50) at a spatial resolution of 500 µm3 , whereas those for T2 remained consistently high ( |r| > 0.85). In the bovine trabecular experiments with intact marrow, low-resolution (approximately 1 mm3 , 2 minutes) T2 values did not shorten ( |r| > 0.95 with respect to approximately 0.4 mm3 , 11 minutes) and maintained consistent correlations ( |r| > 0.70) with respect to trabecular spacing (turbo spin echo, 22.5 minutes). CONCLUSION: T2 measurements of trabeculae at 7 T are robust with degrading spatial resolution and may be preferable in assessing trabecular spacing index with reduced scan time, when high-resolution 3D micro-MRI is difficult to obtain.


Assuntos
Osso Esponjoso/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Animais , Bovinos , Simulação por Computador , Fêmur/diagnóstico por imagem , Método de Monte Carlo , Razão Sinal-Ruído , Joelho de Quadrúpedes/diagnóstico por imagem , Microtomografia por Raio-X
10.
Clin Exp Obstet Gynecol ; 44(2): 264-267, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29746035

RESUMO

PURPOSE OF INVESTIGATION: The authors aimed to determine the relationship between meteorological variables and hypertension in pregnancy by using data from a national weather database. MATERIALS AND METHODS: For this population-based observational study, the database of the Korea National Health Insurance (KNHI) Claims of the Health Insurance Review and Assessment Service (HIRA) and Korea Meteorological Administration was used. The 48,275 women with preeclampsia among 2,495,383 women who gave birth were included. Monthly meteorological factors and preeclampsia prevalence for five years were statistically analyzed. RESULTS: Among temperature, relative humidity, sunlight duration, and rainfall, only relative humidity had a significant inverse correlation with the preeclampsia prevalence (p < 0.001). The other meteorological factors were not associated with preeclampsia. CONCLUSION: Relative humidity may be a significant factor for of the development of preeclampsia. Further monitoring of weather parameters during the entire pregnancy period may be the best method for verifying the present results in the development of preeclampsia.


Assuntos
Umidade/efeitos adversos , Pré-Eclâmpsia , Adulto , Bases de Dados Factuais , Feminino , Humanos , Hipertensão/epidemiologia , Hipertensão/fisiopatologia , Conceitos Meteorológicos , Pré-Eclâmpsia/epidemiologia , Pré-Eclâmpsia/fisiopatologia , Gravidez , Prevalência , República da Coreia/epidemiologia , Fatores de Risco , Estatística como Assunto
11.
Cryo Letters ; 37(4): 284-294, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27925011

RESUMO

BACKGROUND: Despite its self-pollinating characteristics, Korean ginseng germplasm is mainly maintained in clonal gene banks as there is no defined approach to the long-term conservation of its seed, including the most appropriate stage of embryo development for storage. OBJECTIVE: The aim of this study was to reveal the effect of embryo development on desiccation tolerance and cryopreservation success in ginseng seeds. MATERIALS AND METHODS: Seeds of Korean ginseng (Panax ginseng C.A. Meyer) at three post-harvest stages (immediately after harvesting and following treatments to enable internal growth of the embryo) were desiccated and cryopreserved. RESULTS: The hydration window for the >80% dehiscence and germination of cryopreserved ginseng seeds varied with embryo developmental stage: 3-9% moisture content (MC) for both unpulped and undehisced seeds when the embryo was 0.1 the length of the endosperm, 7-10% MC for dehisced seeds (0.5 embryo:endosperm) and 9-11% MC for seeds with fully developed embryos (0.9 embryo:endosperm). Whilst dried (4-8% moisture content) and undehisced seeds within fruits (unpulped seeds) lost more than half their viability during 1 year's storage at room temperature, cryopreservation enabled germination levels of c. 90%. Overall, 432 accessions of Korean ginseng landraces have been cryopreserved using undehisced seeds with or without fruits. CONCLUSION: Post-harvest treatment of Korean ginseng seeds to enable embryo development decreases tolerance of very low MCs, and thus narrows the hydration window for cryopreservation. Fresh-harvested and unpulped seeds that have been dried to c. 5% MC are recommended for long-term cryogenic storage.


Assuntos
Criopreservação , Dessecação , Germinação , Panax/fisiologia , Sementes/crescimento & desenvolvimento
12.
Neuroimage ; 112: 382-389, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-25818683

RESUMO

Intravascular superparamagnetic iron oxide nanoparticles (SPION)-enhanced MR transverse relaxation rates (∆R2(⁎) and ∆R2) are widely used to investigate in vivo vascular parameters, such as the cerebral blood volume (CBV), microvascular volume (MVV), and mean vessel size index (mVSI, ∆R2(⁎)/∆R2). Although highly efficient, regional comparison of vascular parameters acquired using gradient-echo based ∆R2(⁎) is hampered by its high sensitivity to magnetic field perturbations arising from air-tissue interfaces and large vessels. To minimize such demerits, we took advantage of the dual contrast property of SPION and both theoretically and experimentally verified the direct benefit of replacing gradient-echo based ∆R2(⁎) measurement with ultra-short echo time (UTE)-based ∆R1 contrast to generate the robust CBV and mVSI maps. The UTE acquisition minimized the local measurement errors from susceptibility perturbations and enabled dose-independent CBV measurement using the vessel/tissue ∆R1 ratio, while independent spin-echo acquisition enabled simultaneous ∆R2 measurement and mVSI calculation of the cortex, cerebellum, and olfactory bulb, which are animal brain regions typified by significant susceptibility-associated measurement errors.


Assuntos
Vasos Sanguíneos/anatomia & histologia , Volume Sanguíneo/fisiologia , Circulação Cerebrovascular/fisiologia , Imagem Ecoplanar/métodos , Algoritmos , Animais , Simulação por Computador , Compostos Férricos , Processamento de Imagem Assistida por Computador , Masculino , Nanopartículas Metálicas , Camundongos , Camundongos Nus , Microcirculação/fisiologia , Método de Monte Carlo , Reprodutibilidade dos Testes
13.
Phys Rev Lett ; 115(25): 257402, 2015 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-26722943

RESUMO

We used low-energy, momentum-resolved inelastic electron scattering to study surface collective modes of the three-dimensional topological insulators Bi_{2}Se_{3} and Bi_{0.5}Sb_{1.5}Te_{3-x}Se_{x}. Our goal was to identify the "spin plasmon" predicted by Raghu and co-workers [Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary collective mode is a surface plasmon arising from the bulk, free carriers in these materials. This excitation dominates the spectral weight in the bosonic function of the surface χ^{"}(q,ω) at THz energy scales, and is the most likely origin of a quasiparticle dispersion kink observed in previous photoemission experiments. Our study suggests that the spin plasmon may mix with this other surface mode, calling for a more nuanced understanding of optical experiments in which the spin plasmon is reported to play a role.

14.
Neuropathol Appl Neurobiol ; 39(7): 800-16, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23414335

RESUMO

AIMS: Dystrophic neurites are associated with ß-amyloid (Aß) plaques in the brains of Alzheimer's disease (AD) patients and are also found in some specific areas of normal, aged brains. This study assessed the molecular characteristics of dystrophic neurites in normal ageing and its difference from AD. METHODS: We compared the dystrophic neurites in normal aged human brains (age 20-70 years) and AD brains (Braak stage 4-6) by immunostaining against ChAT, synaptophysin, γ-tubulin, cathepsin-D, Aß1-16, Aß17-24, amyloid precursor protein (APP)-CT695 and APP-NT. We then tested the reproducibility in C57BL/6 mice neurone cultures. RESULTS: In normal, aged mice and humans, we found an increase in clustered dystrophic neurites of cholinergic neurones in CA1 regions of the hippocampus and layer II and III regions of the entorhinal cortex, which are the major and earliest affected areas in AD. These dystrophic neurites showed accumulation of sAPPα peptides cleaved from the amyloid precursor protein by α-secretase rather than Aß or C-terminal fragments. In contrast, Aß and APP-CTFs accumulated in the dystrophic neurites in and around Aß plaques of AD patients. Several experiments suggested that the accumulation of sAPPα resulted from ageing-related proteasomal dysfunction. CONCLUSIONS: Ageing-associated impairment of the proteasomal system and accumulation of sAPPα at cholinergic neurites in specific areas of brain regions associated with memory could be associated with the normal decline of memory in aged individuals. In addition, these age-related changes might be the most vulnerable targets of pathological insults that result in pathological accumulation of Aß and/or APP-CTFs and lead to neurodegenerative conditions such as AD.


Assuntos
Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Hipocampo/metabolismo , Neuritos/metabolismo , Adulto , Idoso , Doença de Alzheimer/patologia , Animais , Feminino , Hipocampo/patologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Neurônios , Placa Amiloide/enzimologia , Adulto Jovem
15.
NMR Biomed ; 26(5): 519-32, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23440683

RESUMO

Tumor hypoxia develops heterogeneously, affects radiation sensitivity and the development of metastases. Prognostic information derived from the in vivo characterization of the spatial distribution of hypoxic areas in solid tumors can be of value for radiation therapy planning and for monitoring the early treatment response. Tumor hypoxia is caused by an imbalance between the supply and consumption of oxygen. The tumor oxygen supply is inherently linked to its vasculature and perfusion which can be evaluated by dynamic contrast enhanced (DCE-) MRI using the contrast agent Gd-DTPA. Thus, we hypothesize that DCE-MRI data may provide surrogate information regarding tumor hypoxia. In this study, DCE-MRI data from a rat prostate tumor model were analysed with a Gaussian mixture model (GMM)-based classification to identify perfused, hypoxic and necrotic areas for a total of ten tumor slices from six rats, of which one slice was used as training data for GMM classifications. The results of pattern recognition analyzes were validated by comparison to corresponding Akep maps defining the perfused area (0.84 ± 0.09 overlap), hematoxylin and eosin (H&E)-stained tissue sections defining necrosis (0.64 ± 0.15 overlap) and pimonidazole-stained sections defining hypoxia (0.72 ± 0.17 overlap), respectively. Our preliminary data indicate the feasibility of a GMM-based classification to identify tumor hypoxia, necrosis and perfusion/permeability from non-invasively acquired, in vivo DCE-MRI data alone, possibly obviating the need for invasive procedures, such as biopsies, or exposure to radioactivity, such as positron emission tomography (PET) exams.


Assuntos
Meios de Contraste , Aumento da Imagem , Imageamento por Ressonância Magnética/métodos , Neoplasias da Próstata/patologia , Microambiente Tumoral , Animais , Hipóxia Celular , Linhagem Celular Tumoral , Masculino , Necrose , Distribuição Normal , Reconhecimento Automatizado de Padrão , Neoplasias da Próstata/irrigação sanguínea , Ratos
16.
Nutr Metab Cardiovasc Dis ; 23(8): 785-91, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22762845

RESUMO

BACKGROUND AND AIM: Evidence of the relationship between serum vitamin D levels and cardiovascular risk factors in children is limited. We investigated the associations between serum vitamin D levels (25-hydroxyvitamin D [25(OH)D]) and obesity and metabolic syndrome and its components in Korean children. METHODS AND RESULTS: We recruited 1660, nine-year-old, Korean children (904 boys and 756 girls) who voluntarily participated in this study while being examined during school-based health examinations. We measured anthropometric variables (height and weight), metabolic parameters (blood pressure, fasting plasma glucose, triglyceride, and HDL cholesterol levels) and serum vitamin D levels. We analyzed the data using multivariate logistic regression models. Mean 25(OH)D levels were lower in children defined as obese or abdominally obese (P <0.001). When serum levels of 25(OH)D were divided into quartiles, BMI, waist circumference, and triglyceride levels were lower, and HDL cholesterol levels were higher, as vitamin D levels increased. Using children from the highest quartile of 25(OH)D levels as a referent, the adjusted ORs (95% CI) for obesity in those in the third, second, and lowest quartiles of 25(OH)D levels were 1.55 (1.01-2.40), 1.87 (1.22-2.85), and 2.59 (1.71-3.90), respectively (P for trend <0.001). For abdominal obesity the ORs (CI) were 2.08 (1.20-3.60), 2.32 (1.36-3.95), and 2.96 (1.75-5.00) (P for trend<0.001), and for metabolic syndrome they were 2.60 (1.08-6.30), 4.00 (1.73-9.26), and 4.25 (1.84-9.85), respectively (P for trend <0.05). CONCLUSIONS: We found low vitamin D levels in Korean children to be associated with obesity and metabolic syndrome. Insufficient serum vitamin D levels in children may be a risk factor of obesity and metabolic syndrome.


Assuntos
Síndrome Metabólica/sangue , Obesidade/sangue , Deficiência de Vitamina D/sangue , Vitamina D/análogos & derivados , Povo Asiático , Glicemia/metabolismo , Índice de Massa Corporal , Peso Corporal , Criança , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Estudos Transversais , Jejum , Feminino , Humanos , Modelos Logísticos , Masculino , Síndrome Metabólica/complicações , Análise Multivariada , Inquéritos Nutricionais , Obesidade/complicações , República da Coreia , Fatores de Risco , Triglicerídeos/sangue , Vitamina D/sangue , Deficiência de Vitamina D/complicações , Circunferência da Cintura
17.
J Nanosci Nanotechnol ; 13(5): 3554-8, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23858901

RESUMO

The effect of thermal dissipation by adding graphene nano-platelets to two different commercially available thermal dissipation coatings (ceramic coating and powder coating) was studied. Steady state temperatures of each points of LED modules was monitored in a closed system, with an integral photo detection sphere where there is no external air flow. Having eliminated the contributions of thermal conduction and air flow convection, the module with a conventional heat dissipation coatings showed 8-16% enhancement of thermal dissipation compared to that of non-coated LED module. The addition of graphene is shown to have about 3% additional enhancement. By analyzing thermal resistance of each component of the LED module, the improved thermal conductivity of the graphene added coatings contributes to the enhancement of slight improvement with heat dissipation.


Assuntos
Grafite/química , Iluminação/instrumentação , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Semicondutores , Transferência de Energia , Desenho de Equipamento , Análise de Falha de Equipamento , Temperatura Alta , Tamanho da Partícula , Condutividade Térmica
18.
Diabetologia ; 55(10): 2835-2844, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22772798

RESUMO

AIMS/HYPOTHESIS: The study aimed to evaluate the efficacy of recombinant adenovirus expressing αA-crystallin (Ad-αAc-Gfp) in reducing pericyte loss within retinal vasculature in early diabetes. METHODS: Diabetes was induced by streptozotocin injection into C57BL/6 mice. Ad-αAc-Gfp was delivered by intravitreous injection to the right eyes of mice 2 weeks before induction of diabetes. Vascular leakage was determined by fluorescent angiography, Evans Blue leakage assay and leucocyte adhesion test. Production of αA-crystallin was analysed by immunoblotting and double immunostaining and pericyte loss was analysed by pericyte count. RESULTS: Vessel leakage and pericyte loss were observed in the streptozotocin-induced diabetic retina. Decreased abundance of αA-crystallin in retinas 2 and 6 months after the induction of diabetes was confirmed by two-dimensional electrophoretic analysis, immunoblotting and RT-PCR. Double immunofluorescence staining for αA-crystallin and NG2 chondroitin sulphate proteoglycan revealed that αA-crystallin was predominantly produced in the retinal pericyte and that the number of αA-crystallin-producing pericytes decreased in the diabetic retina. Retinal infection with Ad-αAc-Gfp led to decreased pericyte loss and vascular leakage compared with control. CONCLUSIONS/INTERPRETATION: Intravitreal delivery of Ad-αAc-Gfp protects against vascular leakage in the streptozotocin-induced model of diabetes. This effect is associated with the inhibition of diabetic retinal pericyte loss in early diabetes, suggesting that αA-crystallin has a role in preventing the pathogenesis of early diabetic retinopathy.


Assuntos
Adenoviridae/genética , Apoptose/fisiologia , Diabetes Mellitus Experimental/complicações , Retinopatia Diabética/prevenção & controle , Pericitos/patologia , Cadeia A de alfa-Cristalina/genética , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/metabolismo , Retinopatia Diabética/etiologia , Retinopatia Diabética/patologia , Modelos Animais de Doenças , Sistemas de Liberação de Medicamentos , Glucose/farmacologia , Injeções Intravítreas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pericitos/efeitos dos fármacos , Pericitos/metabolismo , Estreptozocina/efeitos adversos , Resultado do Tratamento , Cadeia A de alfa-Cristalina/administração & dosagem , Cadeia A de alfa-Cristalina/metabolismo
19.
Magn Reson Med ; 65(5): 1437-47, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21287591

RESUMO

Diffusion-weighted imaging plays important roles in cancer diagnosis, monitoring, and treatment. Although most applications measure restricted diffusion by tumor cellularity, diffusion-weighted imaging is also sensitive to vascularity through the intravoxel incoherent motion effect. Hypervascularity can confound apparent diffusion coefficient measurements in breast cancer. We acquired multiple b-value diffusion-weighted imaging at 3 T in a cohort of breast cancer patients and performed biexponential intravoxel incoherent motion analysis to extract tissue diffusivity (D(t)), perfusion fraction (f(p)), and pseudodiffusivity (D(p)). Results indicated significant differences between normal fibroglandular tissue and malignant lesions in apparent diffusion coefficient mean (±standard deviation) values (2.44 ± 0.30 vs. 1.34 ± 0.39 µm(2)/msec, P < 0.01) and D(t) (2.36 ± 0.38 vs. 1.15 ± 0.35 µm(2)/msec, P < 0.01). Lesion diffusion-weighted imaging signals demonstrated biexponential character in comparison to monoexponential normal tissue. There is some differentiation of lesion subtypes (invasive ductal carcinoma vs. other malignant lesions) with f(p) (10.5 ± 5.0% vs. 6.9 ± 2.9%, P = 0.06), but less so with D(t) (1.14 ± 0.32 µm(2)/msec vs. 1.18 ± 0.52 µm(2)/msec, P = 0.88) and D(p) (14.9 ± 11.4 µm(2)/msec vs. 16.1 ± 5.7 µm(2)/msec, P = 0.75). Comparison of intravoxel incoherent motion biomarkers with contrast enhancement suggests moderate correlations. These results suggest the potential of intravoxel incoherent motion vascular and cellular biomarkers for initial grading, progression monitoring, or treatment assessment of breast tumors.


Assuntos
Neoplasias da Mama/patologia , Imagem de Difusão por Ressonância Magnética/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Meios de Contraste , Feminino , Gadolínio DTPA , Humanos , Pessoa de Meia-Idade , Movimento , Neovascularização Patológica/patologia , Software
20.
J Nanosci Nanotechnol ; 11(7): 6262-5, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22121698

RESUMO

Morphology, crystallinity and electrochemical properties of Si powders fabricated by a mechanical milling process with milling time of 6-40 h were investigated by means of FESEM, XRD, Raman, TEM and cell test. Average size of Si powders was reduced to sub-micrometer scale after 10 h-milling and 40 nm-Si powders could be obtained at 48 h-milling. With increasing milling time, Si powders mostly changes from crystalline Si to amorphous one and the content of amorphous Si was increased. TEM result showed that a negligiable amount of crystalline Si remained even after 48 h-milling. Si electrode with 48 h-milled Si powders exhibited the best electrochemical properties in terms of capacity, efficiency and cycle performance: initial capacity of 3025 mAh g(-1), coulrombic efficiency of 79.4% and the capacity retention of 1000 mAh g(-1) (at 130 cycles). The good electrochemical properties of nano- and amorphous-Si are due to the high resistance against volume change and good reversibility of Li ion.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA