Acute Kidney Injury After General Thoracic Surgery: A Systematic Review and Meta-analysis.

INTRODUCTION: The clinical importance of postoperative acute kidney injury (AKI) in patients undergoing general thoracic surgery is unclear. We aimed to systematically review the incidence, risk factors, and prognostic implications of AKI as a complication after general thoracic surgery. METHODS: We searched PubMed, EMBASE, and the Cochrane Library from January 2004 to September 2021. Observational or interventional studies that enrolled ≥50 patients undergoing general thoracic surgery and reported postoperative AKI defined using contemporary consensus criteria were included for meta-analysis. RESULTS: Thirty-seven articles reporting 35 unique cohorts were eligible. In 29 studies that enrolled 58,140 consecutive patients, the pooled incidence of postoperative AKI was 8.0% (95% confidence interval [CI]: 6.2-10.0). The incidence was 3.8 (2.0-6.2) % after sublobar resection, 6.7 (4.1-9.9) % after lobectomy, 12.1 (8.1-16.6) % after bilobectomy/pneumonectomy, and 10.5 (5.6-16.7) % after esophagectomy. Considerable heterogeneity in reported incidences of AKI was observed across studies. Short-term mortality was higher (unadjusted risk ratio: 5.07, 95% CI: 2.99-8.60) and length of hospital stay was longer (weighted mean difference: 3.53, 95% CI: 2.56-4.49, d) in patients with postoperative AKI (11 studies, 28,480 patients). Several risk factors for AKI after thoracic surgery were identified. CONCLUSIONS: AKI occurs frequently after general thoracic surgery and is associated with increased short-term mortality and length of hospital stay. For patients undergoing general thoracic surgery, AKI may be an important postoperative complication that needs early risk evaluation and mitigation.

VMP1 affects endoplasmic reticulum stress sensitivity via differential modulation of the three unfolded protein response arms.

Consisting of three signaling pathways, the unfolded protein response (UPR) can be either protective or detrimental to cells that undergo ER stress. Elaborate regulation of the UPR is key to the cell-fate decision, but how it is achieved remains vague. Here, by studying cells deficient in vacuole membrane protein 1 (VMP1), a UPR regulator, we report a model of UPR regulation in which the three pathways are divergently controlled. Under basal conditions, calcium binding specifically activates PERK. Under ER stress, ER-mitochondria interaction-induced mitochondrial stress cooperates with PERK to suppress IRE1α and ATF6 by decelerating global protein synthesis. Such sophisticated regulation commits limited activation of the UPR yet refrains from UPR hyperactivation, protecting cells from chronic ER stress despite decreasing cell proliferation. Therefore, our study reveals interorganelle-interaction-dependent and calcium-dependent regulation of the UPR that dictates cell fate.

A procedure and device for determining complex material permittivity using the free-space resonance method.

The essential technologies of the complex permittivity of microwave dielectric materials are systematically designed, and the complex permittivity of materials is tested nondestructively by the free-space resonance method. A testing system was built by using a mobile surveying platform, and the complex dielectric constant of the material in the X band was nondestructively tested by using the algorithm of variable physical cavity length and constant physical cavity length. Focusing on the impact of variable physical cavity length on the test results, the cavity calibration technology is proposed to reduce the influence on the complex dielectric constant test of materials. The free-space resonance method was used to test the complex permittivity of polytetrafluoroethylene, glass steel plate (fiber reinforced plastics), and corundum plate. The results show that the test results of complex permittivity obtained by the two algorithms are consistent, and the error of complex permittivity is less than 5%.

Application of time-domain gating technique in water content measurement of gas-liquid two-phase flow.

This paper introduces an application of the time-domain gating technique in water content measurement of gas-liquid two-phase flow. According to the principle that water and gas have different absorption effects on microwaves, a sensor with transmitting and receiving antennas is designed. Combined with the back propagation neural network, the water content of two-phase fluids can be obtained from the complex transmission coefficient (S21) of antennas. In order to reduce the influence of the sensor structure on antenna measurement, the time-domain gating technique can be used to filter out the interference components in S21 so that the water content can be more easily predicted. Built on the above, an automatic test system is established. In the range of 0%-78%, the absolute test error of the water content is lower than 3%.

Quantitative microwave-induced thermoacoustic tomography.

PURPOSE: Microwave-induced thermoacoustic tomography (MI-TAT) is an imaging modality that exploits dielectric contrast while producing images with high ultrasound resolution. Existing reconstruction algorithms for MI-TAT are qualitative and can image only the distribution of the absorbed microwave energy or power loss density. Here the authors describe a method for quantitative MI-TAT and obtain the distribution of dielectric property which directly correlates with tissue structural and functional information. METHODS: The authors implement the quantitative MI-TAT method based on the finite-element (FE) solution to the Helmholtz equation for electromagnetic field coupled with the thermoacoustic wave equation. Regularization techniques are also used in the FE-based reconstruction algorithm. RESULTS: Simulation results are obtained under various practical scenarios including different noise levels, different contrast levels between the heterogeneity and background region, and multiple targets with various sizes and shapes. CONCLUSIONS: The quantitative MI-TAT method described can provide accurate recovery of conductivity distribution in heterogeneous media and is insensitive to noise effect.

A broadband variable-temperature test system for complex permittivity measurements of solid and powder materials.

A microwave test system to measure the complex permittivity of solid and powder materials as a function of temperature has been developed. The system is based on a TM0n0 multi-mode cylindrical cavity with a slotting structure, which provides purer test modes compared to a traditional cavity. To ensure the safety, effectiveness, and longevity, heating and testing are carried out separately and the sample can move between two functional areas through an Alundum tube. Induction heating and a pneumatic platform are employed to, respectively, shorten the heating and cooling time of the sample. The single trigger function of the vector network analyzer is added to test software to suppress the drift of the resonance peak during testing. Complex permittivity is calculated by the rigorous field theoretical solution considering multilayer media loading. The variation of the cavity equivalent radius caused by the sample insertion holes is discussed in detail, and its influence to the test result is analyzed. The calibration method for the complex permittivity of the Alundum tube and quartz vial (for loading powder sample), which vary with the temperature, is given. The feasibility of the system has been verified by measuring different samples in a wide range of relative permittivity and loss tangent, and variable-temperature test results of fused quartz and SiO2 powder up to 1500 °C are compared with published data. The results indicate that the presented system is reliable and accurate. The stability of the system is verified by repeated and long-term tests, and error analysis is presented to estimate the error incurred due to the uncertainties in different error sources.

An estimate of the error caused by the elongation of the wavelength in a focused beam in free-space electromagnetic parameters measurement.

A pair of spot-focusing horn lens antenna is the key component in a free-space measurement system. The electromagnetic constitutive parameters of a planar sample are determined using transmitted and reflected electromagnetic beams. These parameters are obtained from the measured scattering parameters by the microwave network analyzer, thickness of the sample, and wavelength of a focused beam on the sample. Free-space techniques introduced by most papers consider the focused wavelength as the free-space wavelength. But in fact, the incident wave projected by a lens into the sample approximates a Gaussian beam, thus, there has an elongation of the wavelength in the focused beam and this elongation should be taken into consideration in dielectric and magnetic measurement. In this paper, elongation of the wavelength has been analyzed and measured. Measurement results show that the focused wavelength in the vicinity of the focus has an elongation of 1%-5% relative to the free-space wavelength. Elongation's influence on the measurement result of the permittivity and permeability has been investigated. Numerical analyses show that the elongation of the focused wavelength can cause the increase of the measured value of the permeability relative to traditionally measured value, but for the permittivity, it is affected by several parameters and may increase or decrease relative to traditionally measured value.

[Effect of propofol at uptake equilibrium on γ-aminobutyric acid in different cerebral regions in dogs].

OBJECTIVE: To investigate the effect of propofol at doses for different anesthesia depths on γ-aminobutyric acid (GABA) in different cerebral regions at propofol uptake equilibrium in dogs. METHODS: Twelve 12-18-month-old healthy hybrid dogs weighing 10-12 kg were randomly divided into light anesthesia group (n=6) and deep anesthesia group (n=6) with a single bolus dose of propofol (5.5 and 7.0 mg/kg, respectively) completed in 15 s followed by intravenous propofol infusion at a constant rate (55 and 70 mg·kg(-1)·h(-1), respectively). Blood samples (2 ml) were taken from the internal carotid artery and jugular vein to measure plasma propofol concentrations 50 min after the start of the infusion. The dogs were then sacrificed and tissues were taken from different brain regions and the cervical cord to measure GABA concentrations using high-pressure liquid chromatography (HPLC). RESULTS: The plasma propofol concentrations in internal carotid artery and jugular vein were similar in both light anesthesia group (3.00 ± 0.31 and 3.10 ± 0.51 µg/ml, respectively, P>0.05) and deep anesthesia group (6.41 ± 0.05 and 6.40 ± 0.11 µg/ml, respectively, P>0.05). GABA concentrations in the brain regions were significantly higher in deep anesthesia group than in light anesthesia group (P<0.05). The dorsal thalamus and hypothalamus showed greater GABA variations [(83.83 ± 2.230%) and (85.83 ± 1.72)%] compared to other brain regions at different anesthesia depths (P<0.05). CONCLUSIONS: In both groups, plasma propofol concentrations in the internal carotid artery and internal jugular vein reach equilibrium at 50 min of propofol infusion. The variation of GABA is associated with the anesthesia depth of propofol, and GABA variation in the dorsal thalamus and hypothalamus plays an important role in propofol anesthesia.