Stepwise Gradient Research Articles

A Suite of Constitutive Promoters for Tuning Gene Expression in Plants.

The need for convenient tools to express transgenes over a large dynamic range is pervasive throughout plant synthetic biology; however, current efforts are largely limited by the heavy reliance on a small set of strong promoters, precluding more nuanced and refined engineering endeavors in planta. To address this technical gap, we characterize a suite of constitutive promoters that span a wide range of transcriptional levels and develop a GoldenGate-based plasmid toolkit named PCONS, optimized for versatile cloning and rapid testing of transgene expression at varying strengths. We demonstrate how easy access to a stepwise gradient of expression levels can be used for optimizing synthetic transcriptional systems and the production of small molecules in planta. We also systematically investigate the potential of using PCONS as an internal standard in plant biology experimental design, establishing the best practices for signal normalization in experiments. Although our library has primarily been developed for optimizing expression in N. benthamiana, we demonstrate the translatability of our promoters across distantly related species using a multiplexed reporter assay with barcoded transcripts. Our findings showcase the advantages of the PCONS library as an invaluable toolkit for plant synthetic biology.

Pressure–Enhanced Liquid Chromatography as a Suitable Approach to Improve Selectivity for Large Molecule Separations

This work describes the application of a pressure-enhanced liquid chromatography (PE-LC) setup to tune the separation of various large molecules comprised of nucleic acids (oligonucleotides, messenger ribonucleic acid [mRNA], and deoxyribonucleic acid [DNA]). When adding pressure as a method development parameter, it indeed becomes possible to modify retention, selectivity, and peak width. As an example, the separation of oligonucleotides having sizes comprised between 40 and 100-mer in ion-pairing reversed-phase liquid chromatography (IP-RPLC) was drastically improved by using a stepwise pressure gradient to selectively shift the retention of a peak or group of peaks. Resolution was increased from 1.5 to 11.8 when setting a rapid high pressure step (twofold increased pressure) during the run. On the other hand, it was also possible to improve the separation of erythropoietin (EPO) mRNA and related impurities under ion-exchange chromatography (IEX). However, with this biomolecule, the best separation was achieved by reducing the pressure in the system. Finally, for another sample (DNA ladder) under IEX conditions, the pressure was found to have a limited impact on the overall selectivity. As highlighted in this work, pressure is an additional parameter that can be successfully used to develop LC methods of large biomolecules.

Solvothermal Synthesis of Spherical Alumina: Delving into the Formation Mechanism and Morphological Change with Phase Transformation

AbstractSpherical shaped mesoporous alumina was synthesized by a simple solvothermal process at 110 °C/24 h using aluminum nitrate as precursor in the presence of glycerol, diethyl ether and propanol followed by calcination at 900–1100 °C. The transformation of solid spherical γ‐Al2O3 at 900 °C into layered shell spherical α‐Al2O3 at 1000–1100 °C was governed by stepwise temperature gradient (ΔT) along the radial direction of interface with adhesion and contraction forces. XRD analysis confirmed the formation of γ‐Al2O3 at 900 °C and its conversion to α‐Al2O3 at 1000 °C. The N2 adsorption–desorption results showed BET surface area and average pore diameter of γ‐Al2O3 as 77.58 m2 g−1 and 3.7 nm, respectively. The particle size of alumina spheres was in the range of 1–3 μm as confirmed by FESEM and TEM studies. The HRTEM images indicated lattice spacing of 0.21 and 0.23 nm corresponding to γ‐Al2O3 with (400) plane and α‐Al2O3 with (110) plane, respectively. A tentative formation mechanism and the role of glycerol have been explained.

Understanding the zigzags of multi-echo phase signals by numerical simulations

Understanding the multi-echo phase zigzag signals is instrumental to assuring the quality of MRI phase data acquisition for ensuing phase exploration and exploitation. This paper provides a theoretical and computational mechanism for understanding the zigzag multi-echo phase formation that has been observed in numerical multi-echo gradient-recalled (GRE) simulations of clinical complex-valued brain MRI images. Based on intravoxel dephasing mechanism, we calculated a train of multi-GRE complex-valued voxel signals by simulating field gradient reversals under perturbations in either gradient strength (G±δG) or gradient duration (Δ±δΔ), as well as the simultaneous bi-variable gradient perturbations (δGδΔ). In this theoretical experiment, we observed a zigzag line of one-shot multi-echo phase signals at a voxel with respect to linear stepwise field gradient variations in δG ∝ n and δΔ ∝ n (where n denotes the echo index). However, the multi-echo magnitude signals were invariant to field gradient reversal, i.e. no multi-echo magnitude zigzags. To support our simulations, we analyzed the clinical one-shot multi-echo T2*-weighted MRI phase images and found similar multi-echo phase zigzags. In this way, we provide a theoretical and computational understanding of multi-echo phase zigzag artifacts, specifically for the eddy current effect on one-shot multi-GRE signals in practice.

Understanding surface wave modal content for high-resolution imaging of submarine sediments with distributed acoustic sensing

SUMMARY Ocean bottom distributed acoustic sensing (OBDAS) is emerging as a new measurement method providing dense, high-fidelity and broad-band seismic observations from fibre-optic cables deployed offshore. In this study, we focus on 35.7 km of a linear telecommunication cable located offshore the Sanriku region, Japan, and apply seismic interferometry to obtain a high-resolution 2-D shear wave velocity (VS) model below the cable. We first show that the processing steps applied to 13 d of continuous data prior to computing cross-correlation functions (CCFs) impact the modal content of surface waves. Continuous data pre-processed with 1-bit normalization allow us to retrieve dispersion images with high Scholte-wave energy between 0.5 and 5 Hz, whereas spatial aliasing dominates dispersion images above 3 Hz for non-1-bit CCFs. Moreover, the number of receiver channels considered to compute dispersion images also greatly affects the resolution of extracted surface-wave modes. To better understand the remarkably rich modal nature of OBDAS data (i.e. up to 30 higher modes in some regions), we simulate Scholte-wave dispersion curves for stepwise linear VS gradient media. For soft marine sediments, simulations confirm that a large number of modes can be generated in gradient media. Based on pre-processing and theoretical considerations, we extract surface wave dispersion curves from 1-bit CCFs spanning over 400 channels (i.e. ∼2 km) along the array and invert them to image the subsurface. The 2-D velocity profile generally exhibits slow shear wave velocities near the ocean floor that gradually increase with depth. Lateral variations are also observed. Flat bathymetry regions, where sediments tend to accumulate, reveal a larger number of Scholte-wave modes and lower shallow velocity layers than regions with steeper bathymetry. We also compare and discuss the velocity model with that from a previous study and finally discuss the combined effect of bathymetry and shallow VS layers on earthquake wavefields. Our results provide new constraints on the shallow submarine structure in the area and further demonstrate the potential of OBDAS for high-resolution offshore geophysical prospecting.

One-step metal affinity purification of recombinant hFGF19 without using tags

Human fibroblast growth factor 19 (hFGF19) belongs to the endocrine FGF19 superfamily and is considered a potential agent to treat severe or relapsing nonalcoholic fatty liver disease. Numerous studies have confirmed the beneficial effects of this hormone on the related symptoms of the disease and attempts at producing recombinant proteins in various hosts are steadily proliferating. Recently, we reported that authentic hFGF19 can be solubly expressed through combining synonymous codon substitutions and co-expression with disulfide-bond isomerase (DsbC) in Escherichia coli. However, during purification, hFGF19 without the His-tag occasionally co-eluted with His-tagged DsbC when using metal affinity chromatography, thereby requiring auxiliary purification steps to achieve apparent homogeneity. This phenomenon provides evidence that hFGF19 specifically interacts with immobilized Ni2+, which can thus be used as an alternative tool for the purification of hFGF19. Consequently, we could simply and reproducibly purify hFGF19 from cell lysates by using Ni2+-immobilized metal affinity chromatography and stepwise gradient elution with imidazole.

Dual gradients of bioactive components on electrospun fibers for cell migration and controlled stem cell differentiation

The construction of gradient scaffolds to mimic the in vivo microenvironment for promoting tissue regeneration is attractive, especially by incorporating biochemical cues with physical guidance to manipulate cell behavior. Here, we report a general method to generate dual concentration-gradient of two types of bioactive components on scaffolds composed of uniaxially aligned electrospun nanofibers through layer-by-layer self-assembly. Different layers of collagen (COL) and chondroitin sulfate (CS) are sequentially coated onto the specific positions of uniaxially aligned electrospun polycaprolactone (PCL) nanofibers upon electrostatic attraction. In this case, dual stepwise gradients of COL and CS are generated along the fiber alignment. In demonstrating the potential application, the dual gradients can effectively promote the migration and proliferation of bone marrow stem cells (BMSCs) and spatially control their osteogenic differentiation. This simple strategy for generating dual gradients can be easily extended to different types of gradient scaffolds for bone regeneration and related applications involving cell migration, stem cell differentiation, and tissue interface.

High-velocity impact resistance of stepwise gradient sandwich beams with metal foam cores

This paper aims to reveal the impact resistance of the graded sandwich beams subjected to high-velocity impacts experimentally. By using the one-stage gas gun system, the dynamic response and failure of the sandwich beams are analyzed by considering the effects of core gradient, impulsive loading, and boundary condition. The results show that the dynamic structural response of beams is noticeably influenced by the different initial failure mode under the fully clamped condition. The core gradient configuration is confirmed to have no significant effect on the impact resistance performance in terms of the dynamic central deflection, permanent deformation, and failure modes. Under the simply clamped condition, however, the core gradient effect is confirmed to be the predominant factor for the noticeably changed impact resistance performances of the sandwich beams. Due to the advantages on structural response and core compression, the graded sandwich beams have significantly better impact resistance than the uniform sandwich beam under the low-velocity impact. The negative correlation between this advantage and impulsive intensity indicates that impact resistance of the uniform sandwich beam is superior to that of the graded sandwich beams under the intensive impact. This study provides guidance of the gradient designation of the energy absorption sandwich structure and its subsequent engineering applications.

A validated liquid chromatography-tandem mass spectrometry method for the determination of l-hyoscyamine in human plasma: Application in a clinical study.

Atropine is a racemic mixture of d- and l-hyoscyamine, but only l-hyoscyamine is the effective ingredient. In this study, a new, sensitive, stable, and selective LC/MS assay was developed for the determination of l-hyoscyamine and applied to a clinical study. The parent-product (m/z) transition pair of l-hyoscyamine was 290.1 → 124.1. Chromatographic separations were performed using a chiral MZ column (250 mm × 4.6 mm, 5.0 μm) by a stepwise gradient elution mode with n-hexane, isopropanol, and diethylamine as mobile phases. l-Hyoscyamine in human plasma was extracted by liquid-liquid extraction. This assay displayed a good linearity over a concentration range of 20.0-400 pg/mL for l-hyoscyamine. The accuracy of the validation assay for l-hyoscyamine ranged from -2.7% to 4.5%, and the precision was within 6.3% coefficient of variation. l-Hyoscyamine in human plasma remained stable at different storage conditions. The method has been successfully applied to plasma samples obtained from a safety study in humans.

Scalable purification of single stranded DNA scaffolds for biomanufacturing DNA-origami nanostructures: Exploring anion-exchange and multimodal chromatography

DNA-origami biomanufacturing relies in many cases on the use of asymmetric PCR (aPCR) to generate 500–3500 base, object-specific, single-stranded DNA (ssDNA) scaffolds. Each scaffold is usually purified by agarose gel extraction, a technique that is laborious, limited, not scalable, presents low recovery yields and a low-quality product. Alternatively, we present a chromatography-based method to purify ssDNA scaffolds from aPCR mixtures, which can be used in the context of DNA-origami techniques.aPCR was performed to generate single and double-stranded DNA (dsDNA) from the M13mp18 genome. To isolate the target ssDNA from dsDNA and other PCR impurities, anion-exchange (Q-ligand) and multimodal chromatography (CaptoTM adhere ImpRes) were explored using stepwise gradients with increasing NaCl concentrations. In anion exchange chromatography, the less-charged ssDNA eluted before the dsDNA. In multimodal chromatography, however, the elution pattern was reversed, highlighting the importance played by hydrophobicity. In either case, collected ssDNA-containing fractions were homogeneous and impurity free.Finally, 8.4 μg of a 1000-nt ssDNA fragment was purified and used alongside with site-specific short oligonucleotides (staples) to assemble 63-bp edge length tetrahedrons. Gel electrophoresis showed high assembly yield and purity, whereas fluorescence correlation spectroscopy confirmed that the tetrahedrons had a diffusion coefficient (26.7 μm2 s−1) consistent with the expected size (20 nm).

Surrogate modeling of open-celled metal foam sound absorbers with stepwise property gradients

In this paper, we develop a Kriging-based surrogate model to predict the sound absorption performance of open-celled metal foams with user-defined stepwise relative density gradients. An experimentally validated transfer matrix model is used to generate training data capturing the absorption profiles of metal foams with various geometrical parameters. We deploy a spatial analysis method to create influence surfaces around each sample data point and depict its effect on the observed output by using Kriging's basis functions. The surrogate model has an in-built machine learning framework that uses a genetic algorithm and a maximum likelihood function to tune the weights that define these influence surfaces. Using this approach, we successfully developed a data-fed, supervised prediction model that estimates absorption coefficient of a virtual metal foam sample. Post-validation predicted values for unknown sample configurations show satisfactory agreement with their actual absorption coefficients. Finally, we implement the developed metamodel as an iOS application as a potential low-cost tool to reduce testing costs and enable rapid design iterations for acoustic design problems.

Modeling the acoustic behavior of stepwise gradient porous structures

Spatial property gradients can significantly enhance the noise reduction potential of porous structures. However, predicting the acoustic behavior of structures with gradient microstructures continues to remain a challenge. For porous structures with controlled periodic microstructures, researchers have recently demonstrated the use of a multiscale asymptotic method to extract the acoustic transport properties necessary for use in semi-empirical predictive models. Here, we propose the adaptation of this method to enable the modeling of porous absorbers with stepwise property gradients. The unit cell of the chosen microstructure is modeled in COMSOL Multiphysics and the acoustic transport properties are extracted using the multiscale method. The extracted properties are then used to formulate the transfer matrix of each unit cell. The global sound absorption and transmission loss behavior of the stepwise gradient structures are further predicted by combining the appropriate local transfer matrices. Our results show that the integration of the unit cell and transfer matrix methods provides a robust way of predicting the acoustic behavior of stepwise gradient porous structures with various combinations of layer thicknesses and geometries. The method provides a computationally efficient method to model such structures and can further the development of porous structures with application-specific acoustical properties.

Combining high-speed countercurrent chromatography three-phase solvent system with electrospray ionization-mass spectrometry and nuclear magnetic resonance to profile the unconventional food plant Syzygium malaccense

Syzygium malaccense (L.) Merr. & L.M. Perry is a native tree to Malaysia, but also occurs in other tropical regions of the world, including Brazil. The increasing interest in the consumption of its leaves motivated the investigation of compounds of the plant. Metabolite profiling of S. malaccense leaves was achieved by high-speed countercurrent chromatography (HSCCC) fractionation coupled off-line to electrospray mass-spectrometry (ESI-MS) detection and nuclear magnetic resonance (NMR) analysis. The ethanolic leaf extract was submitted to HSCCC using a three-phase solvent system (TPSS) composed by n-hexane – ethyl acetate – acetonitrile – H2O (2:1:1:1, v/v). The stepwise gradient elution was employed due to the extract's chemical complexity. HSCCC fractions were further analyzed by ESI-MS/MS using a flow injection experiment and by NMR acquiring 1H, HSQC and HMBC spectra. MS based dereplication was achieved by comparing acquired data to those available in public and commercial databases. Results were also correlated to previously isolated compounds described for the Syzygium genus. This process led to the annotation of 90 compounds. The NMR data provided structural confirmation and substitution patterns for some of them. Extract chemical composition is characterized by having flavonoids, benzoic acids, hydroxycinnamic acids, quinic acids, hydrolizable tannins, fatty acids, anacardic acids and others primary metabolites. Most of these compounds were described for the first time in the plant. This approach greatly facilitates phytochemical analysis and could be applied to improve metabolite discovery in other studies.

Simultaneous qualitative and quantitative analysis of eight alkaloids in Corydalis Decumbentis Rhizoma (Xiatianwu) and Corydalis Rhizoma (Yanhusuo) by high-performance liquid chromatography and high-resolution mass spectrometry combined with chemometric methods.

In this study, we established a comprehensive high-performance liquid chromatography coupled with diode array detection and high-resolution mass spectrometry method to identify 10 and quantified eight constituents in Corydalis Decumbentis Rhizoma ("Xiatianwu" in Chinese) and Corydalis Rhizoma ("Yanhusuo" in Chinese). Chemometric methods were applied to distinguish the botanical origins of the Xiatianwu and Yanhusuo samples. Chromatographic separation was achieved using an Agilent Poroshell EC-C18 column with mobile phases A (1000ml of 0.2% acetic acid solution containing 2.8ml of triethylamine) and B (acetonitrile) and stepwise gradient elution. The analytical method was fully validated in terms of linearity, sensitivity, intra- and interday precision and repeatability, the limit of detection, the limit of quantitation, and recovery. Twenty-six Xiatianwu samples and 10 Yanhusuo samples were analyzed for quality evaluation. In addition, hierarchical clustering analysis and principal component analysis were used to discriminate among samples of different botanical origins. The results showed that the contents of eight alkaloids in Xiatianwu and Yanhusuo were significantly different. Moreover, it was found that chemometric methods could be applied to accurately distinguish these two often conflated Chinese medicinal materials. In conclusion, this study provides a relatively comprehensive method for botanical origin identification and Xiatianwu and Yanhusuo quality control.

Composition gradient-enabled circular photogalvanic effect in inogranic halide perovskites

Inversion symmetry breaking could lead to the creation of a Rashba–Dresselhauls magnetic field, which plays the key role in spintronic devices. In this work, we propose and develop a composition gradient engineering approach that breaks inversion symmetry into inorganic halide perovskites with strong spin–orbit coupling. We synthesize epitaxial CsPbBrxCl(3−x) with Br/Cl composition gradient by a two-step chemical vapor deposition approach. Through optoelectronic measurements, we show the presence of circular photogalvanic effects (CPGEs), evidencing a Rashba-like spin polarized band structure. By spatially resolved photoluminescence spectra, we find that the observed CPGE is likely a cumulative result of inversion symmetry-broken interfaces featured by abrupt and stepwise composition gradient between the pristine and separated daughter phases. Our work suggests an avenue in engineering the spintronic property of halide perovskites for information processing.

Evaluation of toxicological safety and quality control of Luobufukebiri pill

Ethnopharmacological relevanceThe Luobufukebiri pill is one of the characteristic medicines of Uygur nationality in Xinjiang. It has the effect of warming and tonifying the brain and kidney, benefiting the heart and filling the essential functions, mainly used to treat impotence, depression, spermatorrhea, premature ejaculation, bodily weakness, emaciation, and neurasthenia.Aim of the study: This study evaluated the toxicology and developed a quality control protocol of Luobufukebiri pill to ensure its safety and effectiveness in clinical applications. Materials and methodsAcute toxicity in mice was studied by the maximum-dose method, and the toxic reactions in mice were observed within two weeks. In the study of Sub-chronic toxicity, SD rats were randomized into four groups: three drug groups which were treated with 8.00, 2.67, and 0.80 g/kg of Luobufukebiri pill, respectively, and one control group which was treated with the same volume of distilled water. Subsequently, at 30 days of medication and 30 days of drug withdrawal, the hematologic indexes, biochemical indexes, organ coefficient, and pathological sections of main organs were detected, respectively. According to the prescription, the contents of 8 active components in the pill were quantified simultaneously. The chromatographic conditions were as follows: Stepwise gradient elution was carried out using 0.1% formic acid (solvent A) and acetonitrile (solvent B), 0–8 min, 80% → 60% B; 8–25 min, 60% → 25%B. The flow rate was 1.0 mL/min, the column was maintained at 25 °C, and the injected sample volume was 10 μL. ResultsThe acute toxicity experiment documented a large dose of Luobufukebiri pill had no significant effect on organ and body weight and did not cause apparent damage to parenchymal organs. At Sub-chronic toxicity, the behavior of rats was as normal as the control group. There were some differences in hematologic indexes, serum biochemical indexes, and organ coefficient tests between the drug and control groups, but they had no toxic significance. No obvious pathological changes were observed in the pathological sections of major organs. In conclusion, this study demonstrated that the clinical dose of Luobufukebiri pill was far less than its toxic dose, and it had reliable safety. The contents of eight index components of Luobufukebiri pill were measured. All calibration curves exhibited good linearity with correlation coefficients better than 0.9997. The relative standard deviations of precision, reproducibility, stability, and recovery were less than 2.0%, demonstrating the stability and reliability of the method. ConclusionsThis study further confirmed the safety of Luobufukebiri pill in clinical practice. A rapid, accurate, and convenient RP-HPLC-PDA detection method has been developed for the simultaneous detection of eight active compounds in the pharmaceutical samples of Luobufukebiri pill. This study provided a reference for the safety and enhancement of the quality standards of Luobufukebiri pill.

Sound absorption and transmission loss properties of open-celled aluminum foams with stepwise relative density gradients

We investigate the acoustical properties of uncompressed and compressed open-celled aluminum metal foams fabricated using a directional solidification foaming process. We compressed the fabricated foams using a hydraulic press to different compression ratios and characterized the effect of compression on the cellular microstructure using microtomography and scanning electron microscopy. The static airflow resistances of the samples are measured and related to the observed microstructural changes. We measured the normal incidence acoustical properties using two- and four-microphone impedance tube methods and show that the compression substantially improves their sound absorption and transmission loss performance. We then stack individual disks with different compression ratios to create various stepwise relative density gradient configurations and show that stepwise gradients provide a significant improvement in properties as compared to the uncompressed sample. The effect of increasing and decreasing relative density gradients on the overall absorption and transmission loss behavior is characterized. Finally, we use an experimentally informed and validated transfer matrix method to predict the effect of various layer thicknesses and stacking sequences on the global acoustical properties. Our results show that open-celled metal foams with stepwise relative density gradients can be designed to provide tailored acoustic absorption performance while reducing the overall weight of the noise reduction package.

Chiral separation of catechin and epicatechin by reversed phase high-performance liquid chromatography with β-cyclodextrin stepwise and linear gradient elution modes

Catechin and epicatechin were enantioseparated by high-performance liquid chromatography (HPLC) with a phenyl column and aqueous mobile phases containing 0.05% (w/v) and 0.6% (w/v) of β-cyclodextrin for catechin and epicatechin, respectively. β-Cyclodextrin was found to be scarcely retained on a phenyl column. Consequently, it was suggested that catechin, which was eluted earlier than epicatechin, formed more stable inclusion complex with β-cyclodextrin than epicatechin and earlier eluted enantiomers, (−)-catechin and (+)-epicatechin, formed more stable diastereomer complexes with β-cyclodextrin than the respective enantiomers. This was confirmed by β-cyclodextrin-modified micellar electrokinetic chromatography and Benesi−Hildebrand plots by fluorescence spectrophotometry. Effect of sugars (D-sucrose, D-glucose, and D-fructose) on the epimerization of (+)-catechin and (+)-epicatechin by heating was investigated by HPLC with a β-cyclodextrin stepwise elution mode, in which two kinds of aqueous eluents containing different concentrations of β-cyclodextrin were used by turns. The epimerization of the two enantiomers was suppressed only when D-fructose was added. Separation of ten kinds of catechins including catechin and epicatechin enantiomers was investigated by a β-cyclodextrin linear gradient HPLC elution mode without using organic solvents, where two kinds of aqueous eluents containing different concentrations of β-cyclodextrin were used with changing their ratio gradually. These catechins in a green tea infusion could be separated successfully by this method.

Laparoscopic Complete Excision of the Posterior Muscular Cuff: Technique Refinements and Comparison With Stepwise Gradient Muscular Cuff Cutting for Hirschsprung Disease.

ObjectivesOur institution had modified the Soave pull-through procedure using laparoscopic stepwise gradient muscular cuff cutting (LSGC) for Hirschsprung disease (HSCR). However, we found that a few children still suffered from obstructive symptoms and enterocolitis during the follow-up. Previous studies suggested that these symptoms might be caused by the retained muscular cuff. The purpose of this study was to employ a modified procedure of laparoscopic complete excision of the posterior muscular cuff (LCEPC) for HSCR and compare it with the laparoscopic stepwise gradient cutting muscular cuff (LSGC) procedure.MethodsOur institution records of 83 patients with classic form HSCR who underwent LSGC or LCEPC between August 2014 and July 2018 at the Pediatric Surgery Department of Zunyi Medical University (Zunyi, China) were carefully reviewed (LSGC, n = 52; LCEPC, n = 31). In the present study, we compared the postoperative complications and defecation functions of the two groups. All patients were followed-up (1–5 years, with an average of 2 years).ResultsThere were no differences regarding the operation time and the length of hospitalization between groups, while the anal dissection time in the LCEPC group (22.4 ± 4.8 min) was shorter than that of the LSGC group (45.5 ± 7.5 min) (p < 0.001). The postoperative complication of soiling was significantly increased in six patients (19.4%) in the LCEPC group compared with two patients (3.8%) in the LSGC group (p = 0.021). However, the total incidence of enterocolitis (two patients, 6.5%) was significantly decreased in the LCEPC group compared with the LSGC group (12 patients, 23.1 %) (p = 0.050). For anastomotic stricture, muscular cuff infection, and constipation, there were no significant differences between the two groups. No patients experienced bladder paralysis and incontinence postoperatively in this study. Anorectal manometries presented that the anorectal resting pressure was significantly lower in the LCEPC group (14.8 ± 2.7 mmHg) than the LSGC group (22.0 ± 3.8 mmHg), (p < 0.001).ConclusionThe laparoscopic complete excision of the posterior muscular cuff method was demonstrated as safe and efficient, with a decrease in the incidence of enterocolitis, although it may increase the number of soiling incidents in the short period post-surgery owing to a dissected partial internal anal sphincter.

Temporary Mechanical Circulatory Support Bridging Strategies And Post-operative Outcomes In Acute Decompensated Heart Failure-related Cardiogenic Shock Patients Undergoing Heart Transplantation Or Durable Left Ventricular Assist Device Implantation: A Society Of Thoracic Surgeons Database Analysis

Introduction Temporary mechanical circulatory support (TMCS) bridging strategies are increasingly used for acute decompensated heart failure-related cardiogenic shock (ADHF-CS). However, the impact of bridging approach on post-operative outcomes in ADHF-CS patients who receive a durable left ventricular assist device (LVAD) or heart transplant (HT) is unknown. Methods Durable LVAD or HT recipients from July 1, 2014 to December 31, 2019 with pre-operative ADHF-CS were identified in the Society of Thoracic Surgeons Adult Cardiac Surgery Database and stratified by pre-operative TMCS strategy. Associations between TMCS strategies and post-operative outcomes were evaluated using propensity-score matching and adjustment for pre-selected covariates (pre-operative hemoglobin, platelets, albumin, bilirubin, international normalized ratio, creatinine, cardiopulmonary resuscitation, and operative status). Results A total of 8,777 ADHF-CS patients were bridged to LVAD (5,975; 68%) or HT (2,802; 32%). The composite of operative/30-day death following LVAD or HT was highest in patients managed with VA ECMO (22%) and lowest in those managed without TMCS (7%), with a stepwise gradient of incidence by level of hemodynamic support (Figure, top). Other post-operative outcomes including major bleeding, cerebrovascular accident, cardiac arrest, prolonged mechanical ventilation, renal failure, and sepsis/pneumonia followed a similar pattern. However, after propensity score matching and adjustment, there were no differences in the odds of operative/30-day death or major bleeding with IABP versus no TMCS (Figure, bottom). While there was no difference in operative/30-day death, odds of major bleeding were lower with catheter-based MCS compared with IABP (OR 0.70, 95% CI 0.53 - 0.92). Conclusion ADHF-CS patients experience high rates of cardiac and non-cardiac adverse events post- LVAD and HT. A crude relationship between TMCS bridging strategy and post-operative outcomes was observed. However, after adjustment, pre-operative TMCS bridging strategy did not independently confer risk of near-term post-operative mortality among ADHF-CS patients who underwent HT or durable LVAD implantation. Temporary mechanical circulatory support (TMCS) bridging strategies are increasingly used for acute decompensated heart failure-related cardiogenic shock (ADHF-CS). However, the impact of bridging approach on post-operative outcomes in ADHF-CS patients who receive a durable left ventricular assist device (LVAD) or heart transplant (HT) is unknown. Durable LVAD or HT recipients from July 1, 2014 to December 31, 2019 with pre-operative ADHF-CS were identified in the Society of Thoracic Surgeons Adult Cardiac Surgery Database and stratified by pre-operative TMCS strategy. Associations between TMCS strategies and post-operative outcomes were evaluated using propensity-score matching and adjustment for pre-selected covariates (pre-operative hemoglobin, platelets, albumin, bilirubin, international normalized ratio, creatinine, cardiopulmonary resuscitation, and operative status). A total of 8,777 ADHF-CS patients were bridged to LVAD (5,975; 68%) or HT (2,802; 32%). The composite of operative/30-day death following LVAD or HT was highest in patients managed with VA ECMO (22%) and lowest in those managed without TMCS (7%), with a stepwise gradient of incidence by level of hemodynamic support (Figure, top). Other post-operative outcomes including major bleeding, cerebrovascular accident, cardiac arrest, prolonged mechanical ventilation, renal failure, and sepsis/pneumonia followed a similar pattern. However, after propensity score matching and adjustment, there were no differences in the odds of operative/30-day death or major bleeding with IABP versus no TMCS (Figure, bottom). While there was no difference in operative/30-day death, odds of major bleeding were lower with catheter-based MCS compared with IABP (OR 0.70, 95% CI 0.53 - 0.92). ADHF-CS patients experience high rates of cardiac and non-cardiac adverse events post- LVAD and HT. A crude relationship between TMCS bridging strategy and post-operative outcomes was observed. However, after adjustment, pre-operative TMCS bridging strategy did not independently confer risk of near-term post-operative mortality among ADHF-CS patients who underwent HT or durable LVAD implantation.