Detecção quantitativa de vírus BK em receptores de transplante renal : um estudo prospectivo de validação

Introduction: BK virus (BKV) infection in renal transplant patients may cause kidney allograft dysfunction and graft loss. Accurate determination of BKV viral load is critical to prevent BKV-associated nephropathy (BKVAN) but the cut-off that best predicts BKVAN remains controversial. Objective: To evaluate the performance of a commercial and an in-house qPCR test for quantitative detection of BK virus in kidney transplant recipients. Methods: This was a prospective study with kidney transplant recipients from two large university hospitals in Brazil. Patients were screened for BKV infection every 3 months in the first year post-transplant with a commercial and an in-house real time polymerase chain reaction (qPCR) test. BKVAN was confirmed based on histopathology. The area under the curve for plasma qPCR was determined from receiver operating characteristic analysis. Results: A total of 200 patients were enrolled. Fifty-eight percent were male, 19.5% had diabetes mellitus, and 82% had the kidney transplanted from a deceased donor. BKV viremia was detected in 32.5% and BKVAN was diagnosed in 8 patients (4%). BKVAN was associated with viremia of 4.1 log copies/ mL, using a commercial kit. The cut-off for the in-house assay was 6.1 log copies/ mL. The linearity between the commercial kit and the in-house assay was R2 =0.83. Conclusion: Our study shows that marked variability occurs in BKV viral load when different qPCR methodologies are used. The in-house qPCR assay proved clinically useful, a cheaper option in comparison to commercial qPCR kits. There is an urgent need to make BKV standards available to the international community.Introdução: A infecção pelo vírus BK (BKV) em pacientes de transplante renal pode levar a disfunção do aloenxerto renal e perda do enxerto. A determinação precisa da carga viral do BKV é fundamental para prevenir a nefropatia associada ao BKV (BKVAN), mas o ponto de corte de melhor valor preditivo para BKVAN ainda é foco de debates. Objetivo: Avaliar o desempenho de um teste de qPCR comercial e outro desenvolvido internamente para detecção quantitativa de vírus BK em receptores de transplante renal. Métodos: O presente estudo prospectivo incluiu receptores de transplante renal de dois grandes hospitais universitários no Brasil. Os pacientes foram testados para infecção por BKV a cada três meses no primeiro ano pós-transplante com um teste comercial de reação em cadeia de polimerase quantitativa em tempo real (qPCR) e outro desenvolvido internamente. A presença de BKVAN foi confirmada com base na histopatologia. A área sob a curva para o qPCR plasmático foi determinada a partir da análise da característica de operação do receptor. Resultados: Um total de 200 pacientes foram incluídos. Cinquenta e oito por cento eram do sexo masculino, 19,5% tinham diabetes mellitus e 82% tiveram seus rins transplantados de doadores falecidos. Viremia de BKV foi detectada em 32,5% dos pacientes e oito (4%) foram diagnosticados com BKVAN. BKVAN foi associada a viremia de 4,1 log cópias/mL usando o kit comercial. O corte para o ensaio interno foi de 6,1 log cópias/ mL. A linearidade entre o kit comercial e o ensaio interno foi R2 = 0,83. Conclusão: Nosso estudo demonstrou uma acentuada variabilidade na carga viral de BKV quando diferentes metodologias de qPCR foram utilizadas. O ensaio interno de qPCR mostrou- -se clinicamente útil, além de ser uma opção menos onerosa em relação aos kits comerciais de qPCR. Há uma necessidade urgente de se definir padrões de BKV para a comunidade internacional

Calibration of Granier-Type (TDP) Sap Flow Probes by a High Precision Electronic Potometer

Thermal dissipation probe (TDP) method (Granier, 1985) is widely used to estimate tree transpiration (i.e., the water evaporated from the leaves) because it is simple to build, easy to install, and relatively inexpensive. However, the universality of the original calibration has been questioned and, in many cases, proved to be inaccurate. Thus, when the TDP is used in a new species, specific tests should be carried out. Our aim was to propose a new method for improving the accuracy of TDP on trees in the field. Small hazelnut trees (diameter at breast height 5 cm) were used for the experiment. The response of TDP sensors was compared with a reference water uptake measured with an electronic potometer system provided with a high precision liquid flow meter. We equipped three stems where we measured the sap flow density, the sapwood area (by using fuchsine), the total tree water uptake (reference), and the main meteorological parameters during summer 2018. Results confirmed that the original Granier’s calibration underestimated the effective tree transpiration (relative error about −60%). We proposed a new equation for improving the measurement accuracy within an error of about 4%. The system proposed appeared an easier solution compared to potted trees and particularly suitable for orchards, thus contributing to improve the irrigation management worldwide

Dual-laser, self-calibrating Thomson scattering measurements in RFX-mod

A self-calibrating Thomson scattering technique, based on using two lasers of different wavelength and never implemented before in a fusion experiment, is tested for the first time in RFX-mod. The method employs two laser systems, Nd:YAG (\u3bb = 1064 nm) and Nd:YLF (\u3bb = 1053 nm), fired in sync through the same plasma volume. The combination of the two scattered spectra, individually recorded, is used to simultaneously obtain the measurements of the electron temperature Te and the relative calibration coefficients of the polychromator spectral channels sensitivities Ci. This work is a continuation of the dual-angle technique, a similar alternative method. Due to the small difference in the wavelengths of the two lasers, the sensitivity of this method is low in RFX-mod and reliable measurements of the calibration coefficients could not be obtained on a shot-to-shot basis, but only with a statistical analysis of a reasonable number of pairs of laser shots with good signal-to-noise ratio. The dual-laser method can be applied to most fusion devices and could provide continuous online monitoring of the spectral transmission of the detection system. This may prove essential in larger devices (ITER), where access for traditional calibration is difficult

Design and R&D of Thermal Sensors for ITER Neutral Beam Injectors

In-vessel components of Megavolt ITER Injector and Concept Advancement, the ITER neutral beam injector prototype, will be instrumented with different sensor technologies mainly for protection and thermal control: thermocouples (TCs) will be used as thermal sensors distributed on all the in-vessel components, accelerometers as boiling detectors mounted on tubes of cooling channels subjected to high heat fluxes, fiber Bragg gratings as thermal sensors on high-voltage panels, strain gauges (SGs) as strain sensors on panels subjected to out-of-plane deformations. ITER in-vacuum cabling requires to use mineral insulated (MI) cables that exhibit radiation hardness and Ultra High Vacuum (UHV) compatibility. A common issue related to sensors cabled with MI (TCs, accelerometers, and SGs) involves the realization of UHV compatible terminations needed with provide vacuum tightness and mechanical robustness. Prototypes of MI TCs with 0.5-, 0.8-, and 1.0-mm cable diameter and with metallic/ceramic brazed terminations have been procured and tested; all sensors passed electrical and leak tests, including electrical insulation, continuity, dielectric, helium bombing, and thermal cyclic tests, so demonstrating the measuring capability and UHV compatibility. Custom sensor fastenings, custom remote handling compatible connectors, and safety important signal feedthroughs have been designed considering all the boundary conditions and the required number of sensors as obtained from the analyses

Design of JT-60SA core Thomson scattering diagnostic system

JT-60SAでは電子温度と電子密度の分布を計測するためにトムソン散乱計測システムを設置する。本発表では、ポートプラグ内の限られた空間に設置可能な集光光学系、レーザー伝送系、分光器、制御システムの概念設計を示す。集光光学系はポートプラグからは独立した片持ち張り構造とし、ディスラプション等が原因となる変位の影響を抑制する。電子温度の計測誤差は、10%以下であると評価され、プラズマ研究に十分な精度で計測できる見込みを得た。第23回高温プラズマ計測に関するトピカル会議(HTPD

Design of JT-60SA core Thomson scattering diagnostic system

An incoherent Thomson scattering diagnostic will be installed in the JT-60SA tokamak to measure electron temperature and electron density profiles. The target radial spatial resolution is 25 mm with 46 spatial channels. The accuracy in electron temperature and density is a few percent at ne = 7.5 × 10^19 m^−3 , which is the expected value in the plasma core. This paper presents the designs of collection optics, fibers with their alignment system, and polychromators. The collection optics overcomes unique issues for superconducting fusion devices, i.e., limited design space, high-temperature measurements, and harsh radiation condition. When in several years the more performing plasma will generate intense nuclear radiation, the lens materials of the optics can be replaced by radiation resistant glasses without major changes in the lens holder. It will prevent transmission degradation and keep stable measurement accuracy