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1.
MAGMA ; 33(1): 113-120, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31823276

RESUMO

OBJECTIVE: Blood oxygenation level dependent (BOLD) MRI technique is used to evaluate changes in intra-renal oxygenation in chronic kidney disease (CKD). The purpose of this study was to evaluate if the novel twelve layer concentric objects (TLCO) method has advantages over the manually defined regions of interest (ROI) analysis. METHODS AND MATERIALS: Existing renal BOLD MRI data acquired before and after furosemide on a 3 T scanner from 41 CKD patients and 13 age matched healthy controls were analyzed using TLCO method and compared with previously reported ROI analysis. RESULTS: Regional R2* measurements were strongly correlated between the two methods, while ΔR2* was moderately correlated. Medullary R2* by ROI analysis showed higher values compared to R2*_Inner by TLCO, probably due to the contributions from the cortex to R2*_Inner. R2*_Slope and Δ(R2*_Slope), unique parameters based on the TLCO method provided the most significant differences between stage 3a CKD patients and controls and were correlated with eGFR. DISCUSSION: There was a high degree of agreement between the two methods in terms of regional R2* measurements and both methods did not show differences between moderate CKD patients and controls. However, R2*_Slope and Δ(R2*_Slope) showed the largest sensitivity in distinguishing CKD from controls.

2.
Am J Nephrol ; 49(2): 114-124, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30669143

RESUMO

BACKGROUND: Chronic hypoxia is a well-recognized factor in the pathogenesis of chronic kidney disease (CKD). Loss of microcirculation is thought to lead to enhanced renal hypoxia, which in turn results in the development of fibrosis, a hallmark of progressive CKD. To evaluate the role of functional magnetic resonance imaging (MRI), we performed perfusion, oxygenation, and diffusion MRI measurements in individuals with diabetes and stage 3 CKD. METHODS: Fifty-four subjects (41 individuals with diabetes and stage 3 CKD and 13 healthy controls) participated in this study. Data with blood oxygenation level dependent (BOLD), arterial spin labeling perfusion and diffusion MRI were acquired using a 3T scanner. RESULTS: Renal cortical perfusion was reduced in CKD compared to the controls (109.54 ± 25.38 vs. 203.17 ± 27.47 mL/min/100 g; p < 0.001). Cortical apparent diffusion coefficient showed no significant reduction in CKD compared to controls (1,596.10 ± 196.64 vs. 1,668.72 ± 77.29 × 10-6 mm2/s; p = 0.45) but was significantly associated with perfusion. Cortical R2* values were modestly increased in CKD (20.76 ± 4.08 vs. 18.74 ± 2.37 s-1; p = 0.12). Within the CKD group, R2*_Medulla and R2*_Kidney were moderately and negatively associated with estimated glomerular filtration rate. There was a significant association between cortical perfusion and medullary response to furosemide with annual loss of renal function, used as an estimate of CKD progression. CONCLUSIONS: Subjects with a moderate degree of CKD had significantly lower renal perfusion. Diffusion and BOLD MRI showed more modest differences between the groups. Individuals with progressive CKD had lower perfusion and response to furosemide.

4.
J Magn Reson Imaging ; 48(2): 514-521, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29517835

RESUMO

BACKGROUND: Identification of patients with progressive chronic kidney disease (CKD) and those likely to respond to candidate therapeutics is urgently needed. Functional MRI measurements have shown promise. However, knowledge about the consistency of the measurements is essential to conduct longitudinal studies. PURPOSE/HYPOTHESIS: To investigate the consistency of repeated functional MRI measurements in healthy subjects. STUDY TYPE: Prospective, longitudinal study. SUBJECTS: Seventeen healthy subjects were examined on two different occasions, 18 months apart. FIELD STRENGTH/SEQUENCE: Multiple gradient-recalled-echo, 2D navigator-gated flow-sensitive alternating inversion recovery True-FISP and spin-echo planar diffusion-weighted sequences were used on a 3T scanner. Images were acquired on two different scanner configurations. ASSESSMENT: Blood oxygenation level-dependent (BOLD) R2*, arterial spin labeling (ASL) perfusion-derived blood flow (BF) and apparent diffusion coefficient (ADC) maps were analyzed using a custom image processing toolbox. Regions of interest (ROIs) were placed on renal cortex, medulla, and whole kidney. Multiple researchers were involved in defining the ROIs. STATISTICAL TESTS: Intra- and intersubject coefficients of variation (CV) and Bland-Altman plots were used to measure consistency and evaluate bias in the measurements. A nonparametric Wilcoxon test was used to compare differences between two timepoints. RESULTS: The intrasubject CV for R2* and ADC were 6.8% and 5.3% with small (-3.8 and 5.3%) bias, respectively, comparing baseline and 18-month data. Intrasubject CV for renal cortex BF was higher (18.7%) compared to R2* and ADC, but comparable to prior literature values over shorter durations. It also exhibited a larger bias (-15.4%) between two timepoints and significantly lower values (P = 0.022) at 18-month data. DATA CONCLUSION: All three MRI parameters over 18 months, even with a scanner upgrade and involving multiple observers, showed good consistency. These results are useful for the interpretation of longitudinal data and support the use of these methods to monitor progression in patients with CKD. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2018;48:514-521.


Assuntos
Testes de Função Renal , Rim/diagnóstico por imagem , Imagem por Ressonância Magnética , Adulto , Idoso , Índice de Massa Corporal , Progressão da Doença , Taxa de Filtração Glomerular , Voluntários Saudáveis , Humanos , Estudos Longitudinais , Pessoa de Meia-Idade , Estudos Prospectivos , Circulação Renal , Reprodutibilidade dos Testes , Marcadores de Spin
5.
Opt Lett ; 42(21): 4533-4536, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29088206

RESUMO

In this work, III-nitride based ∼370 nm UVA light-emitting diodes (LEDs) grown on Si substrates are demonstrated. We also reveal the impact of the AlN composition in the AlGaN quantum barrier on the carrier injection for the studied LEDs. We find that, by properly increasing the AlN composition, both the electron and hole concentrations in the multiple quantum wells (MQWs) are enhanced. We attribute the increased electron concentration to the better electron confinement within the MQW region when increasing the AlN composition for the AlGaN barrier. The improved hole concentration in the MQW region is ascribed to the reduced hole blocking effect by the p-type electron blocking layer (p-EBL). This is enabled by the reduced density of the polarization-induced positive charges at the AlGaN last quantum barrier (LB)/p-EBL interface, which correspondingly suppresses the hole depletion at the AlGaN LB/p-EBL interface and decreases the valence band barrier height for the p-EBL. As a result, the optical power is improved.

6.
Materials (Basel) ; 10(10)2017 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-29073738

RESUMO

The hole injection is one of the bottlenecks that strongly hinder the quantum efficiency and the optical power for deep ultraviolet light-emitting diodes (DUV LEDs) with the emission wavelength smaller than 360 nm. The hole injection efficiency for DUV LEDs is co-affected by the p-type ohmic contact, the p-type hole injection layer, the p-type electron blocking layer and the multiple quantum wells. In this report, we review a large diversity of advances that are currently adopted to increase the hole injection efficiency for DUV LEDs. Moreover, by disclosing the underlying device physics, the design strategies that we can follow have also been suggested to improve the hole injection for DUV LEDs.

7.
Kidney Int Rep ; 2(1): 36-43, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28868513

RESUMO

INTRODUCTION: Chronic kidney disease (CKD) is known to be associated with reduced renal blood flow. However, data to-date in humans is limited. METHODS: In this study, non-invasive arterial spin labeling (ASL) MRI data was acquired in 33 patients with diabetes and stage-3 CKD, and 30 healthy controls. RESULTS: A significantly lower renal blood flow both in cortex (108.4±36.4 vs. 207.3±41.8; p<0.001, d=2.52) and medulla (23.2±8.9 vs. 42.6±15.8; p<0.001, d=1.5) was observed. Both cortical (ρ=0.67, p<0.001) and medullary (ρ=0.62, p<0.001) blood flow were correlated with eGFR, and cortical blood flow was found to be confounded by age and BMI. However, in a subset of subjects that were matched for age and BMI (n=6), the differences between CKD and control subjects remained significant both in cortex (107.4±42.8 vs. 187.51±20.44; p=0.002) and medulla (15.43±8.43 vs. 39.18±11.13; p=0.002). A threshold value to separate healthy and CKD was estimated to be Cor_BF=142.9 and Med_BF=24.1. CONCLUSION: These results support the use of ASL in the evaluation of renal blood flow in patients with moderate level of CKD. Whether these measurements can identify subjects at risk of progressive CKD requires further longitudinal follow-up.

8.
Opt Express ; 25(14): 16550-16559, 2017 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-28789158

RESUMO

The drift velocity for holes is strongly influenced by the electric field in the p-type hole injection layer for III-nitride based deep ultraviolet light-emitting diodes (DUV LEDs). In this work, we propose an electric-field reservoir (EFR) consisting of a p-AlxGa1-xN/p-GaN architecture to facilitate the hole injection and improve the internal quantum efficiency (IQE). The p-AlxGa1-xN layer in the EFR can well reserve the electric field that can moderately adjust the drift velocity and the kinetic energy for holes. As a result, we are able to enhance the thermionic emission for holes to cross over the p-EBL with a high Al composition provided that the composition in the p-AlxGa1-xN layer is properly optimized to avoid a complete hole depletion therein.

9.
ACS Appl Mater Interfaces ; 9(8): 7368-7375, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28067037

RESUMO

A tunable nanosphere lithography (NSL) technique is combined with metal-assisted etching of silicon (Si) to fabricate ordered, high-aspect-ratio Si nanowires. Non-close-packed structures are directly prepared via shear-induced ordering of the nanospheres. The spacing between the nanospheres is independent of their diameters and tuned by changing the loading of nanospheres. Nanowires with spacings between 110 and 850 nm are easily achieved with diameters between 100 and 550 nm. By eliminating plasma or heat treatment of the nanospheres, the diameter of the nanowires fabricated is nearly identical to the nanosphere diameter in the suspension. The elimination of this step helps avoid common drawbacks of traditional NSL approaches, leading to the high-fidelity, large-scale fabrication of highly crystalline, nonporous Si nanowires in ordered hexagonal patterns. The ability to simultaneously control the diameter and spacing makes the NSL technique more versatile and expands the range of geometries that can be fabricated by top-down approaches.

10.
Twin Res Hum Genet ; 19(6): 697-707, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27677539

RESUMO

The aim of the present work was to determine maternal and fetal outcomes of intrahepatic cholestasis of pregnancy (ICP) in twin pregnancies. All twin pregnancies delivered above 28 gestational weeks in West China Second University Hospital from January 2013 to May 2015 were included. Data on maternal demographics and obstetric complications together with fetal outcomes were collected. The risk of adverse maternal and fetal outcomes were determined in relation to ICP by crude odds ratios (OR) and adjusted ORs (aOR) with 95% confidence intervals (CI). Subgroup analysis concentrated on the effect of assisted reproductive technology (ART), ICP severity, and onset time. A total of 1,472 twin pregnancies were included, of which 362 were cholestasis patients and 677 were conceived by ART. Higher rates of preeclampsia (aOR 1.96; 95% CI 1.35, 2.85), meconium-stained amniotic fluid (aOR 3.10; 95% CI 2.10, 4.61), and preterm deliveries (aOR 3.20; 95% CI 2.35, 4.37) were observed in ICP patients. Subgroup analysis revealed higher incidences of adverse outcomes in severe and early onset ICP groups. In conclusion, adverse maternal and fetal outcomes were strongly associated with ICP in twin patients. Active management and close antenatal monitoring are needed, especially in the early onset and severe groups.


Assuntos
Colestase Intra-Hepática/epidemiologia , Complicações na Gravidez/epidemiologia , Gravidez de Gêmeos , Nascimento Prematuro/epidemiologia , Adulto , China , Colestase Intra-Hepática/fisiopatologia , Feminino , Feto/fisiopatologia , Idade Gestacional , Humanos , Recém-Nascido , Gravidez , Complicações na Gravidez/fisiopatologia , Resultado da Gravidez , Nascimento Prematuro/fisiopatologia , Técnicas de Reprodução Assistida
11.
Artigo em Chinês | MEDLINE | ID: mdl-27276820

RESUMO

OBJECTIVE: To investigate the effectiveness of ileal mucosal seromuscular patch for bladder expansion combined with rehabilitation training for treating neurogenic bladder dysfunction (NBD) with hyperreflexia. METHODS: A retrospective study was performed on the clinical data of 61 patients with NBD and hyperreflexia who were treated and followed up between July 2008 and June 2013. There were 36 males and 25 females, aged 6-23 years (mean, 10 years). The reasons included meningomyelocele operation (43 patients),surgery for lipoma in lumbar vertebra (4 patients), operation of thoracolubar teratoma (2 patients), and lumbosacral spina B3ifida (12 patients). The results of urodynamics indicated that bladder volume decreased obviously and the residual urine increased. The voiding cystourethrography (VCUG) showed the vesicoureteral reflux (VUR), including 6 cases (10 sides) of grade V, 7 cases (12 sides) of grade IV, and 6 cases (8 sides) of grade III. The color doppler ultrosound showed mild hydronephrosis in 23 cases (41 sides), moderate hydronephrosis in 25 cases (42 sides), and severe hydronephrosis in 13 cases (22 sides). The blood biochemical examination suggested chronic renal failure (CRF) in 13 cases. The treatment included augmentation for bladder and rehabilitation training after operation. RESULTS: The operation time was (157+/- 26) minutes; the intraoperative blood loss was (43 +/- 15) mL, and no patient was given blood transfusion. The patients were followed up 1.5-6.0 years (mean, 4.5 years). Vesical fistula occurred in 4 cases, urinary infection in 5 cases, dysuresia in 2 cases, and cystolith in 1 case after operation. At 1 year after operation, the International Consultation on Incontinence Questionnaire-Urinary Incontience Short Form (IQ-F) score was significantly better than peoperative score (H=9.813, P=0.000). The aurdynmic data showed that the difference value between observed and theoretical bladder volumes, bladder compliance, residual urine volume, maximum flow rate, and maximum storage detrusor pressure were significantly better than preoperative ones (P<0.05). And the color doppler ultrasound showed mild hydronephrosis in 34 cases (56 sides), moderate hydronephrosis in 18 cases (33 sides), and severe hydronephrosis in 9 cases (16 sides). VCUG showed that bladder volume obviously increased, no contracture was observed; and VUR was improved. And renal function was improved in 13 patients with CRF. CONCLUSION: Heal mucosal seromuscular patch for bladder expansion combined with postoperative rehabilitation training has good effectiveness in treating NBD with hyperreflexia.


Assuntos
Reflexo Anormal , Bexiga Urinaria Neurogênica/reabilitação , Refluxo Vesicoureteral/diagnóstico , Adolescente , Criança , Feminino , Humanos , Hidronefrose , Masculino , Estudos Retrospectivos , Ultrassonografia Doppler em Cores , Micção , Urodinâmica , Refluxo Vesicoureteral/cirurgia , Adulto Jovem
12.
Nanotechnology ; 27(16): 165303, 2016 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-26953775

RESUMO

Silicon nanowires (SiNWs) are appealing building blocks in various applications, including photovoltaics, photonics, and sensors. Fabricating SiNW arrays with diameters <100 nm remains challenging through conventional top-down approaches. In this work, chemical etching and thermal oxidation are combined to fabricate vertically aligned, sub-20 nm SiNW arrays. Defect-free SiNWs with diameters between 95 and 200 nm are first fabricated by nanosphere (NS) lithography and chemical etching. The key aspects for defect-free SiNW fabrication are identified as: (1) achieving a high etching selectivity during NS size reduction; (2) retaining the circular NS shape with smooth sidewalls; and (3) using a directional metal deposition technique. SiNWs with identical spacing but variable diameters are demonstrated by changing the reactive ion etching power. The diameter of the SiNWs is reduced by thermal oxidation, where self-limiting oxidation is encountered after oxidizing the SiNWs at 950 °C for 1 h. A second oxidation is performed to achieve vertically aligned, sub-20 nm SiNW arrays. Si/SiO2 core/shell NWs are obtained before removing the oxidized shell. HRTEM imaging shows that the SiNWs have excellent crystallinity.

13.
Chem Commun (Camb) ; 52(14): 2928-31, 2016 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-26688107

RESUMO

Selective desorption of (6,5) single-wall carbon nanotubes from hydrogels only occurs at specific co-surfactant ratios. High-purity fractions are obtained at this ratio even with long elution times and different total co-surfactant concentrations. These results suggest that each (n,m) type forms a thermodynamically-stable surfactant structure in the co-surfactant solution, enabling high-fidelity separations in a single column.


Assuntos
Hidrogéis , Nanotubos de Carbono , Tensoativos/química
14.
PLoS One ; 10(10): e0139661, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26430736

RESUMO

BACKGROUND: The current clinical classification of chronic kidney disease (CKD) is not perfect and may be overestimating both the prevalence and the risk for progressive disease. Novel markers are being sought to identify those at risk of progression. This preliminary study evaluates the feasibility of magnetic resonance imaging based markers to identify early changes in CKD. METHODS: Fifty-nine subjects (22 healthy, 7 anemics with no renal disease, 30 subjects with CKD) participated. Data using 3D volume imaging, blood oxygenation level dependent (BOLD) and Diffusion MRI was acquired. BOLD MRI acquisition was repeated after 20 mg of iv furosemide. RESULTS: Compared to healthy subjects, those with CKD have lower renal parenchymal volumes (329.6±66.4 vs. 257.1±87.0 ml, p<0.005), higher cortical R2* values (19.7±3.2 vs. 23.2±6.3 s(-1), p = 0.013) (suggesting higher levels of hypoxia) and lower response to furosemide on medullary R2* (6.9±3.3 vs. 3.1±7.5 s(-1), p = 0.02). All three parameters showed significant correlation with estimated glomerular filtration rate (eGFR). When the groups were matched for age and sex, cortical R2* and kidney volume still showed significant differences between CKD and healthy controls. The most interesting observation is that a small number of subjects (8 of 29) contributed to the increase in mean value observed in CKD. The difference in cortical R2* between these subjects compared to the rest were highly significant and had a large effect size (Cohen's d = 3.5). While highly suggestive, future studies may be necessary to verify if such higher levels of hypoxia are indicative of progressive disease. Diffusion MRI showed no differences between CKD and healthy controls. CONCLUSIONS: These data demonstrate that BOLD MRI can be used to identify enhanced hypoxia associated with CKD and the preliminary observations are consistent with the chronic hypoxia model for disease progression in CKD. Longitudinal studies are warranted to further verify these findings and assess their predictive value.


Assuntos
Falência Renal Crônica/patologia , Estudos de Casos e Controles , Estudos Transversais , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino
15.
World J Gastroenterol ; 21(34): 9927-35, 2015 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-26379397

RESUMO

AIM: To develop a practical and reproducible rat model of hepatorenal syndrome for further study of the pathophysiology of human hepatorenal syndrome. METHODS: Sprague-Dawley rats were intravenously injected with D-galactosamine and lipopolysaccharide (LPS) via the tail vein to induce fulminant hepatic failure to develop a model of hepatorenal syndrome. Liver and kidney function tests and plasma cytokine levels were measured after D-galactosamine/LPS administration, and hepatic and renal pathology was studied. Glomerular filtration rate was detected in conscious rats using micro-osmotic pump technology with fluorescein isothiocyanate-labelled inulin as a surrogate marker. RESULTS: Serum levels of biochemical indicators including liver and kidney function indexes and cytokines all significantly changed, especially at 12 h after D-galactosamine/LPS administration [alanine aminotransferase, 3389.5 ± 499.5 IU/L; blood urea nitrogen, 13.9 ± 1.3 mmol/L; Cr, 78.1 ± 2.9 µmol/L; K(+), 6.1 ± 0.5 mmol/L; Na(+), 130.9 ± 1.9 mmol/L; Cl(-), 90.2 ± 1.9 mmol/L; tumor necrosis factor-α, 1699.6 ± 599.1 pg/mL; endothelin-1, 95.9 ± 25.9 pg/mL; P < 0.05 compared with normal saline control group]. Hepatocyte necrosis was aggravated gradually, which was most significant at 12 h after treatment with D-galactosamine/LPS, and was characterized by massive hepatocyte necrosis, while the structures of glomeruli, proximal and distal tubules were normal. Glomerular filtration rate was significantly decreased to 30%-35% of the control group at 12 h after D-galactosamine/LPS administration [Glomerular filtration rate (GFR)1, 0.79 ± 0.11 mL/min; GFR2, 3.58 ± 0.49 mL/min·kgBW(-1); GFR3, 0.39 ± 0.99 mL/min·gKW(-1)]. The decreasing timing of GFR was consistent with that of the presence of hepatocyte necrosis and liver and kidney dysfunction. CONCLUSION: The joint use of D-galactosamine and LPS can induce liver and kidney dysfunction and decline of glomerular filtration rate in rats which is a successful rat model of hepatorenal syndrome.


Assuntos
Galactosamina , Síndrome Hepatorrenal/induzido quimicamente , Rim/fisiopatologia , Lipopolissacarídeos , Fígado/fisiopatologia , Animais , Citocinas/sangue , Modelos Animais de Doenças , Taxa de Filtração Glomerular , Síndrome Hepatorrenal/sangue , Síndrome Hepatorrenal/patologia , Síndrome Hepatorrenal/fisiopatologia , Rim/metabolismo , Rim/patologia , Fígado/metabolismo , Fígado/patologia , Masculino , Necrose , Ratos Sprague-Dawley , Fatores de Tempo
16.
Invest Radiol ; 50(12): 821-7, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26193455

RESUMO

OBJECTIVES: The aim of this study was to determine a robust (sensitive and objective) method for analyzing renal blood oxygenation level-dependent magnetic resonance imaging data. MATERIALS AND METHODS: Forty-seven subjects (30 with chronic kidney disease [CKD] and 17 controls) were imaged at baseline and after furosemide with a multiecho gradient recalled echo sequence. Conventional analysis consisted of regional segmentation (small cortex, large cortex, and medulla), followed by computing the mean of each region. In addition, we segmented the entire parenchyma and computed the mean (µ1) plus higher moments (µ2, µ3, and µ4). Two raters performed each of the segmentation steps, and agreement was assessed with intraclass correlation coefficients (ICCs). We used a measure of effect size (Cohen's d value), in addition to the usual measure of statistical significance, P values, for determining significant results. RESULTS: The mean of the renal parenchyma showed the highest agreement between raters (ICC, 0.99), and the higher parenchyma moments were on par with large cortical region of interest (ROI) ICC. The renal parenchymal mean also exhibited significant sensitivity to changes after furosemide administration in healthy subjects (P = 0.002, d = 0.84), in agreement with medullary ROIs (P = 0.002, d = 1.59). When comparing controls and subjects with CKD at baseline, cortical ROI showed a significant difference (P = 0.015, d = -0.69), whereas the parenchyma ROI did not (P = 0.152, d = 0.39). Post-furosemide data in all regions resulted in a significant difference (large cortex: P = 0.026, d = -0.51; medulla: P = 0.019, d = -0.61) with the renal parenchyma ROI resulting in the largest effect size (P = 0.003, d = -0.75). Higher moments of the renal parenchyma showed similar significant differences as well. CONCLUSIONS: Overall, our data support the use of the entire parenchyma to evaluate changes in the medulla after administration of furosemide, a widely used pharmacological maneuver. Changes in higher moments indicate that there is more than just a shift in the mean renal R2* and may provide clinically relevant information without the need for subjective regional segmentation. For evaluating differences between controls and subjects with CKD at baseline; large cortical ROI provided the highest sensitivity and objectivity. A combination of renal parenchyma assessment and large cortical ROI may provide the most robust method of evaluating renal blood oxygenation level-dependent magnetic resonance imaging data.


Assuntos
Rim/irrigação sanguínea , Imagem por Ressonância Magnética , Oxigênio/sangue , Insuficiência Renal Crônica/sangue , Insuficiência Renal Crônica/diagnóstico , Adulto , Feminino , Furosemida/administração & dosagem , Humanos , Masculino , Sensibilidade e Especificidade
17.
ACS Appl Mater Interfaces ; 7(23): 12824-31, 2015 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-26010178

RESUMO

Electron recombination in dye-sensitized solar cells (DSSCs) results in significant electron loss and performance degradation. However, the reduction of electron recombination via blocking layers in nanowire-based DSSCs has rarely been investigated. In this study, HfO2 or TiO2 blocking layers are deposited on nanowire surfaces via atomic layer deposition (ALD) to reduce electron recombination in nanowire-based DSSCs. The control cell consisting of ITO nanowires coated with a porous shell of TiO2 by TiCl4 treatment yields an efficiency of 2.82%. The efficiency increases dramatically to 5.38% upon the insertion of a 1.3 nm TiO2 compact layer between the nanowire surface and porous TiO2 shell. This efficiency enhancement implies that porous sol-gel coatings on nanowires (e.g., via TiCl4 treatment) result in significant electron recombination in nanowire-based DSSCs, while compact coatings formed by ALD are more advantageous because of their ability to act as a blocking layer. By comparing nanowire-based DSSCs with their nanoparticle-based counterparts, we find that the nanowire-based DSSCs suffer more severe electron recombination from ITO due to the much higher surface area exposed to the electrolyte. While the insertion of a high band gap compact layer of HfO2 between the interface of the conductive nanowire and TiO2 shell improves performance, a comparison of the cell performance between TiO2 and HfO2 compact layers indicates that charge collection is suppressed by the difference in energy states. Consequently, the use of high band gap materials at the interface of conductive nanowires and TiO2 is not recommended.

18.
Invest Radiol ; 50(6): 392-6, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25668748

RESUMO

OBJECTIVES: The objective of this study was to assess whether streptozotocin (STZ)-induced diabetic rats develop iodinated contrast-induced acute kidney injury. The intrarenal R2* (=1/T2*) was evaluated continuously before, during, and after contrast administration. Renal injury was confirmed using urinary neutrophil gelatinase-associated lipocalin measurements. MATERIALS AND METHODS: Six Sprague-Dawley rats were administered with STZ to induce diabetes (group 1). R2* was measured before, during, and after administration of iodixanol. R2* readings were sampled from 4 renal regions: inner medulla, inner stripe of outer medulla (ISOM), outer stripe of outer medulla, and cortex. Peak R2* and initial upslope of R2* increase after iodinated contrast were calculated. Data from 12 nondiabetic rats pretreated with nitric oxide synthase and prostaglandin inhibitors to induce susceptibility to contrast-induced acute kidney injury (pretreatment model) from a previous study were reanalyzed for peak R2* and initial upslope of R2* increase after contrast. Six of these animals received saline (group 2), and the other 6 received furosemide (group 3) before iodixanol. RESULTS: Peak R2* and initial upslope of R2* increase were used as blood-oxygenation-level-dependent response parameters. R2* in ISOM was comparable in all 3 groups before administration of furosemide/saline. Except for the furosemide group, ISOM showed a rapid increase in R2* immediately after contrast administration. Unlike the L-NAME- and indomethacin-treated groups, the diabetic group showed a quick reversal of R2* toward baseline measurements after contrast administration. Urinary neutrophil gelatinase-associated lipocalin indicated significant increase in diabetic rats 4 hours after contrast administration. The observed trends with peak R2* and initial upslope of R2* increase in renal ISOM were in agreement with those of urinary neutrophil gelatinase-associated lipocalin. CONCLUSIONS: The STZ-induced diabetic rat may be suitable for studying the effects of iodinated contrast on renal oxygenation status and may mimic human condition closer than the pretreatment model described before. The peak R2* value and initial upslope of R2* in ISOM appear to be effective magnetic resonance imaging markers to predict renal injury after administration of an iodinated contrast agent.


Assuntos
Proteínas da Fase Aguda/urina , Meios de Contraste/metabolismo , Diabetes Mellitus Experimental/urina , Nefropatias/urina , Lipocalinas/urina , Imagem por Ressonância Magnética , Proteínas Proto-Oncogênicas/urina , Ácidos Tri-Iodobenzoicos/urina , Animais , Meios de Contraste/efeitos adversos , Diabetes Mellitus Experimental/complicações , Modelos Animais de Doenças , Nefropatias/induzido quimicamente , Nefropatias/complicações , Ratos , Ratos Sprague-Dawley , Ácidos Tri-Iodobenzoicos/efeitos adversos
19.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 32(1): 113-6, 2015 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-25636114

RESUMO

Aldehyde dehydrogenase 2 (ALDH2), as one of the most important alcohol metabolizing enzymes, plays a significant role in the detoxification process of acetaldehyde which is a main carcinogenic product of alcoholic metabolism. Alteration in its genotypes (particularly at the site of rs671) is closely associated with a variety of tumors in drinkers. Recent advance in the research of the association of the ALDH2 gene rs671 polymorphisms with cancer susceptibility in drinkers is reviewed.


Assuntos
Consumo de Bebidas Alcoólicas/genética , Aldeído Desidrogenase/genética , Predisposição Genética para Doença , Neoplasias/genética , Polimorfismo Genético , Aldeído-Desidrogenase Mitocondrial , Humanos , Neoplasias/etiologia
20.
Nephrology (Carlton) ; 20(3): 194-200, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25470073

RESUMO

BACKGROUND: Rapid diagnosis and initiation of the treatment on congenital obstructive nephropathy are important for young children to slow down renal injury. The aim of our study was to investigate the role of urinary extracellular matrix metalloproteinase inducer (Emmprin), matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) in the long-term follow-up of children with ureteropelvic junction (UPJ) narrowing on conservative treatment. METHODS: The study included 40 children with non-obstructed hydronephrosis due to unilateral UPJ narrowing who were treated conservatively and followed up for 24 months. Voided urine samples were collected at diagnosis and at 3, 9, 15 and 24 months of follow-up, respectively. Three enzymes concentrations were measured in urine. RESULTS: During the follow-up, 25 children showed renal function stabilization (non-obstructed group) and 15 children renal function deterioration (obstructed group). In the non-obstructed group, a comparison between urine three enzymes levels at the last follow-up and at baseline showed no significant differences (all P > 0.05). Glomerular filtration rate (GFR) and split renal function (SRF) showed similar trends. In the obstructed group, a comparison between the three enzymes levels at diagnosis and at basal condition showed a significant increase (all P < 0.01). But GFR and SRF showed a marked reduction at diagnosis (all P < 0.001). Receiver operator characteristic (ROC) analyses revealed a better diagnostic profile for uEmmprin, uMMP-9 and uTIMP-1 in identifying children with abnormal SRF (<40%) at 24 months of follow-up [area under the curve (AUC) 0.877, 0.727 and 0.823, respectively]. CONCLUSIONS: Urinary Emmprin, MMP-9 and TIMP-1 may be noninvasive potential biomarkers that could be used for long-term follow-up of children with UPJ narrowing on conservative treatment to determine those who might develop obstruction.


Assuntos
Basigina/urina , Ensaios Enzimáticos Clínicos , Hidronefrose/diagnóstico , Metaloproteinase 9 da Matriz/urina , Inibidor Tecidual de Metaloproteinase-1/urina , Obstrução Ureteral/diagnóstico , Fatores Etários , Área Sob a Curva , Biomarcadores/urina , Criança , Pré-Escolar , China , Estudos Transversais , Progressão da Doença , Feminino , Humanos , Hidronefrose/congênito , Hidronefrose/terapia , Hidronefrose/urina , Lactente , Masculino , Projetos Piloto , Valor Preditivo dos Testes , Curva ROC , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Obstrução Ureteral/congênito , Obstrução Ureteral/terapia , Obstrução Ureteral/urina
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