Structural studies of a bacterial condensin complex reveal ATP-dependent disruption of intersubunit interactions.

Condensins are key mediators of chromosome condensation across organisms. Like other condensins, the bacterial MukBEF condensin complex consists of an SMC family protein dimer containing two ATPase head domains, MukB, and two interacting subunits, MukE and MukF. We report complete structural views of the intersubunit interactions of this condensin along with ensuing studies that reveal a role for the ATPase activity of MukB. MukE and MukF together form an elongated dimeric frame, and MukF's C-terminal winged-helix domains (C-WHDs) bind MukB heads to constitute closed ring-like structures. Surprisingly, one of the two bound C-WHDs is forced to detach upon ATP-mediated engagement of MukB heads. This detachment reaction depends on the linker segment preceding the C-WHD, and mutations on the linker restrict cell growth. Thus ATP-dependent transient disruption of the MukB-MukF interaction, which creates openings in condensin ring structures, is likely to be a critical feature of the functional mechanism of condensins.

Four-Dimensional Visualization of Microscale Dynamics of Membrane Oil Fouling via Synchrotron Radiation Microcomputed Tomography.

Although oil-water separation technology via wettability-controlled membranes has emerged as a promising technology to treat oily wastewater, membrane fouling by faulents such as sludge flocs and colloids, and the consequent clogging of pores, severely degrades the efficiency of filtration systems. One of the main promotors of fouling by faulents is oil fouling, which is also a form of fouling itself. Despite considerable practical and academic interest in the analysis of oil-fouled membranes, direct visualization of the entire process of oil infiltration into hydrophilic membranes is still preliminary owing to (i) the similar optical contrast and physical density between oil and water, (ii) the low penetration depth of imaging methods, and (iii) the lack of 3D segmentation capability. In this study, microcomputed X-ray tomography using tunable synchrotron radiation provided direct high-speed 3D visualization of the microscale dynamics of the oil infiltration of a prewetted hydrophilic filter membrane over time. Direct visualization of the interfacial dynamics of oil infiltration opens a window into the complex liquid (water/oil)-gas-solid interface and thus helps furnish an in-depth understanding of oil fouling in the prewetted membrane.

Pore-Scale Investigation of Dynamic Immiscible Displacement in Layered Media using Synchrotron X-ray Microtomography.

Understanding the dynamics of immiscible fluid in a porous media is critical in many chemical and environmental engineering processes. However, the geological heterogeneity effect on multiphase flow behavior remains unclear. Here, the dynamics of immiscible fluid displacement and entrapment were experimentally demonstrated at pore-level using time-lapse synchrotron X-ray microtomography. A drainage-imbibition experiment was designed using an unconsolidated layered sand pack that comprised coarse sand and fine sand zones. There were significant differences between the two zones, with regard to the temporal variations in fluid saturation and morphological evolution of nonwetting fluid (oil) during imbibition. Highly connected oil clusters in the coarse zone broke up into many small fragments, whereas the cluster in the fine zone remained connected while spanning multiple pores. To further understand the impacts of pore size and connectivity on multiphase fluid dynamics, a new approach that tracks the temporal variation of immiscible fluid in individual pores was conducted. The surface area at the oil-water interface increased during imbibition, which is expected to facilitate mass transfer and surface interactions. Understanding immiscible fluid displacement in layered porous media at the pore-level could lead to more effective environmental remediation.

Long-Term Outcomes of Surgical Repair for Ventricular Septal Defect in Adults.

Data of the outcomes of ventricular septal defect (VSD) closure in adults are limited to establish recommendations. Therefore, we reviewed our experience with surgical VSD closure in adult patients. We retrospectively reviewed 152 patients who underwent surgical VSD closure between January 1996 and April 2020. The median age of the patients was 30.5 [interquartile range (IQR) 23.1-42.7] years. The median follow-up duration was 10.9 (IQR 4.8-16.1) years. VSDs were classified according to the Society of Thoracic Surgeons classification as type 2 (n = 66, 43.4%), type 1 (n = 59, 38.8%), and type 4 (n = 27, 17.8%). Aortic cusp prolapse (n = 86, 56.6%) and aortic valve regurgitation (AR, n = 75, 49.3%) were the most common indications for surgical closure. Four patients underwent late reoperation (2.6%) due to AR, infective endocarditis and residual VSD. In the log-rank test, preoperative trivial or more degree of AR (P = 0.004) and coronary cusp deformity (P = 0.031) was associated with late moderate or greater degree of AR. Preoperative moderate or greater AR was associated with reoperation (P = 0.047). Only concomitant aortic valve (AV) repair at the time of VSD closure was a significant risk factor for late significant AR progression in the multivariable analysis. VSD closure in adults can be performed with low mortality and morbidity rates. AR can progress after VSD closure because the aortic cusp may have irreversible damage from long-standing shunt flow exposure. We conclude that VSD with AV deformity or AR in adults should be treated aggressively before disease progression with irreversible damage occurs.

Tricuspid Valve Repair at Pulmonary Valve Replacement in Repaired Tetralogy of Fallot.

BACKGROUND: Pulmonary valve replacement (PVR) is often performed in patients with repaired tetralogy of Fallot (TOF). Concomitant tricuspid valvuloplasty (TVP) in those with tricuspid regurgitation (TR) at the time of PVR is still controversial. METHOD: We retrospectively reviewed clinical records of patients who underwent PVR between 2001 and 2012. We analyzed the impact of concomitant TVP on the tricuspid valve function and right ventricle function and size in mid-term. RESULTS: 119 patients with mild to moderate TR at the time of PVR were enrolled. 33 patients underwent concomitant TVP (TVP group) and 86 patients underwent PVR alone (no-TVP group). There was a significant reduction of TR (p < 0.001) and right ventricular end-diastolic volume index (RVEDVi) (p < 0.001). However, in patients who showed prosthetic pulmonary valve (PV) failure at the last follow-up, there was no significant decrease in TR regardless of concomitant TVP. In the patients with preserved prosthetic PV function, TR was significantly improved (p < 0.001 in both groups). The multivariable analysis showed that significant risk factors for recurrence of significant TR were preoperative moderate TR and prosthetic PV failure. CONCLUSIONS: After PVR in repaired TOF patients, there was an improvement in the degree of TR and the RVEDVi. Concomitant TVP at the time of PVR may not be able to prevent the recurrence of TR when prosthetic PV failure occurs; however, it may effectively preserve tricuspid valve function until that time.

High-resolution fast-tomography brain-imaging beamline at the Taiwan Photon Source.

The new Brain Imaging Beamline (BIB) of the Taiwan Photon Source (TPS) has been commissioned and opened to users. The BIB and in particular its endstation are designed to take advantage of bright unmonochromatized synchrotron X-rays and target fast 3D imaging, ∼1 ms exposure time plus very high ∼0.3 µm spatial resolution. A critical step in achieving the planned performances was the solution to the X-ray induced damaging problems of the detection system. High-energy photons were identified as their principal cause and were solved by combining tailored filters/attenuators and a high-energy cut-off mirror. This enabled the tomography acquisition throughput to reach >1 mm3 min-1, a critical performance for large-animal brain mapping and a vital mission of the beamline.

Coordination of multiple dual oxidase-regulatory pathways in responses to commensal and infectious microbes in drosophila gut.

All metazoan guts are in permanent contact with the microbial realm. However, understanding of the exact mechanisms by which the strength of gut immune responses is regulated to achieve gut-microbe mutualism is far from complete. Here we identify a signaling network composed of complex positive and negative mechanisms that controlled the expression and activity of dual oxidase (DUOX), which 'fine tuned' the production of microbicidal reactive oxygen species depending on whether the gut encountered infectious or commensal microbes. Genetic analyses demonstrated that negative and positive regulation of DUOX was required for normal host survival in response to colonization with commensal and infectious microbes, respectively. Thus, the coordinated regulation of DUOX enables the host to achieve gut-microbe homeostasis by efficiently combating infection while tolerating commensal microbes.

Domino-like water transport on Tillandsia through flexible trichome wings.

Tillandsia usneoides in epiphytic bromeliads takes up water through absorptive trichomes on the shoot surface under extreme environmental conditions. Although previous studies revealed the way by which T. usneoides absorbs water and prevents water loss, its water transport remains unclear. We characterized structures of trichome wings of T. usneoides. Wing length-to-thickness ratio of 136 and trichome interval (d)-to-wing length (l) ratio (d/l) smaller than 1 caused the water film to flatten the wings sequentially, resulting in domino-like water transport. A hinge-like linkage between wing and outer ring cells and the wing size longer than the elastocapillary length (LEC ) brought about this unique reconfiguration, which is the flattening and recovery of wings. Tillandsia usneoides transported water rapidly on the surface as the water film propagated on the exterior trichomes with flexible wings and the transport distance at the macroscopic scale grew as tx with x = 0.68 ± 0.04, unlike the conventional scaling of t0.5 . Empirical and theoretical investigations proved our assumption that external water transport with the domino-like effect predominated over internal vascular transport. Biomimetic trichome wings simulated the domino-like water transport, highlighting the important role of flexible wing arrays.

Long-Term Outcomes of Atrioventricular Valve Surgery in Patients with Functional Single Ventricle: Should We Avoid Valve Replacement?

Atrioventricular valve regurgitation (AVVR) is associated with increased morbidity and mortality in patients with single ventricle physiology. The purpose of this study was to evaluate the long-term results of the surgical management of AVVR and to analyze the effects of AV valve replacement. The medical records of 38 single ventricle patients who underwent atrioventricular valve surgery more than once between January 2001 and March 2018 were retrospectively reviewed. We analyzed and compared clinical data of patients who underwent valve replacement as an initial treatment (n = 8) for AVVR with patients who initially underwent valve repair (n = 30). The median follow-up duration was 98.1 months (range, 0.9-209.6 months). There was one early mortality and seven late mortalities. Freedom from reoperation between the two groups at 15 years of follow-up was significantly different: 18.3% in the repair group and 100% in the replacement group (p = 0.013). The replacement group showed a better overall survival rate (100%) at 15 years than the repair group (68.5%) without statistical significance (p = 0.097). All mortalities occurred in the repair group. Nine patients in the repair group (30%) and one patient in the replacement group (12.5%) showed preoperative ventricular dysfunction. RV-type single ventricle with atrioventricular (AV) valve annular dilatation was found out as a risk factor of AVV replacement both in univariate (p = 0.04) and multivariate (p = 0.004) analysis. AV valve replacement might be considered as a primary treatment option for patients who have an annular dilation with an RV-type single ventricle rather than repeated valvuloplasty.

Twenty-Year Experience with Truncus Arteriosus Repair: Changes in Risk Factors in the Current Era.

Although the clinical outcomes of truncus arteriosus (TA) repair have been improving, few data are available on long-term outcomes after truncus arteriosus repair in the current era. This study evaluated long-term outcome after repair of TA. Fifty-one patients underwent total correction from April 1982 to June 2018. Since 2003, perioperative strategy has changed to minimal priming volume, modified ultrafiltration, and early total repair (n = 26). Mortality and reoperation rates were analyzed before and after 2003. There were 8 hospital deaths after initial operation, all before 1997. During the mean follow-up of 9.8 years, there were 2 deaths. The Kaplan-Meier estimate of survival among all hospital survivors was 94.7% at 5 years and 88.0% at 20 years. A significant independent risk factor for early mortality was operation before 2003 (Hazard ratio (HR) 9.710, p = 0.041) and REV operation (HR 8.000, p = 0.028). Freedom from reoperation for conduit change and TV repair were 88.3% and 41% at 1 and 5 years, and 96.2% and 85.4% at 1 and 5 years, respectively. After 2003, younger age and conduit choice were risk factors for conduit-related reoperation. Initial preoperative TV regurgitation was independent risk factor for sequential TV repair. Patients with TA can undergo total repair of TA with excellent results, especially in current era. Most of the patients require conduit-related reoperations. Younger age and the methods of RVOT reconstruction were risk factors for conduit-related reoperations. TV repair is necessary in limited patients, and initial regurgitation was a risk factor.

Direct Measurement of Contact Angle Change in Capillary Rise.

Capillary rise is important in many aspects of physical phenomena from transport in porous media to biotechnology. It is typically described by the Lucas-Washburn-Rideal equation (LWRE), but discrepancy between some experiments and the model still remains elusive. In this paper, we show that the discrepancy is simply from the contact angle change during the capillary rise with no help of any specific models, such as dynamic contact angle (DCA) models. To demonstrate this, we directly measure the contact angle change in the capillary rise for glycerol and carboxymethyl cellulose solutions as examples of Newtonian and non-Newtonian liquids. Unlike previous studies that used DCA models to explain the discrepancy, when the contact angle change is directly applied to the LWRE for all four tested fluids, the model agrees well with experimental data. The estimated contact angle from the capillary rise as a function of time is in good agreement with the directly measured contact angle within a narrow margin of error. To pinpoint the conditions for the discrepancy, we propose a new time scale when contact angle dynamics dominates. The contact angle dynamics that can be obtained from the macroscopic capillary rise may provide useful information for capillary flow in a more complicated geometry such as porous media.

Experience with Temporary Centrifugal Pump Bi-ventricular Assist Device for Pediatric Acute Heart Failure: Comparison with ECMO.

Though ventricular assist devices (VADs) are an important treatment option for acute heart failure, an extracorporeal membrane oxygenator (ECMO) is usually used in pediatric patients for several reasons. However, a temporary centrifugal pump-based Bi-VAD might have clinical advantages versus ECMO or implantable VADs. From January 2000 to July 2018, we retrospectively reviewed 36 pediatric patients who required mechanical circulatory support (MCS) for acute heart failure. Cases with postoperative MCS were excluded. Since 2016, we have tried to immediately add a right VAD rather than ECMO, when the patients begin to present features of right heart failure after left VAD support started in cases that the patients' respiratory function did not require an oxygenator. Original diagnoses included dilated cardiomyopathy (n = 18), myocarditis (n = 11), and others (n = 7). Eleven patients were supported by Bi-VAD, and 25 patients were supported by ECMO; of these. Four patients were successfully weaned from VAD, and 10 patients were weaned from ECMO. Eleven patients underwent heart transplantation. Overall, we have 15 (41.7%) early mortalities. There were no significant differences in early mortality, morbidity, and weaning rate between the Bi-VAD group and the ECMO group. During the support, patients with Bi-VADs significantly required fewer platelets and showed less hemolysis than ECMO patients. Patients with myocarditis were successfully weaned from Bi-VAD support and bridged to transplantation thereafter. A temporary centrifugal pump-based Bi-VAD was clinically comparable to ECMO for pediatric patients with acceptable pulmonary function.

High-Throughput Analysis of New Bone Formation and Bone Substitutes After Maxillary Sinus Floor Elevation Using Synchrotron Radiation Micro-Computed Tomography.

This study addresses the usability of synchrotron radiation micro-computed tomography (SR-µCT) for the high-throughput examination of bone biopsy specimens harvested from maxillary sinus floor elevation (MSFE) patients. The experimental procedure devised for efficient data acquisition and volume analysis of bone biopsy specimens of sinus lift using SR-µCT is presented. The measuring was done in approximately one minute per field of view; 3D image visualization and volume analysis could be performed in one hour. Six months after the sinus floor augmentation procedure, bone biopsy specimens were collected. Six specimens were studied. The percentages of bone measured by 3D volumetric analysis using SR-µCT and 2D area analysis using conventional histomorphometry were compared. A specimen was measured in any cross section, and the analysis was readily extended to the entire volume of the specimen. Significant differences between the 2D and the 3D measurement results were revealed. Based on our observations, we report structural inhomogeneity in the grafted volume of the MSFE site. The new bone volume assessed by SR-µCT correlates with the percentage of bone as assessed by conventional 2D histologic photomicrographs. SR-µCT is thus a reliable technique to determine the volume of newly formed bone at the MSFE.

Surgery on a dilated aorta associated with a connective tissue disease or inflammatory vasculitis in children and adolescents.

INTRODUCTION: This research investigated patients who underwent surgery for a dilated aorta associated with a connective tissue disease or inflammatory vasculitis in children and adolescents. MATERIALS AND METHODS: The medical records of 11 patients who underwent aortic surgery for dilatation resulting from a connective tissue disease or inflammatory vasculitis between 2000 and 2017 were retrospectively reviewed. RESULTS: The median age and body weight of the patients were 9.6 years (range 5.4 months-15.5 years) and 25.8 kg (range 6.8-81.5), respectively. The associated diseases were Marfan syndrome (n = 3), Loeys-Dietz syndrome (n = 3), Kawasaki disease (n = 1), Takayasu arteritis (n = 1), PHACE syndrome (n = 1), tuberous sclerosis (n = 1), and unknown (n = 1). The most common initially affected area was the ascending aorta. During the 66.4 ± 35.9 months of follow-up, two Marfan syndrome patients died, and four patients (one Marfan syndrome and three Loeys-Dietz syndrome) had repeated aortic operation. Except for one patient, the functional class was well maintained in all patients who were followed up. CONCLUSION: Cases of surgical treatment for a dilated aorta associated with a connective tissue disease and inflammatory vasculitis are rare in children and adolescents at our institution. Most of the patients in this study showed a tolerable postoperative course. However, the aorta showed progressive dilation over time even after surgical treatment, especially in patients with Loeys-Dietz syndrome. In these patients, close and more frequent regular follow-up is required.

One-Year Follow-up After Tetralogy of Fallot Total Repair Preserving Pulmonary Valve and Avoiding Right Ventriculotomy.

BACKGROUND: We reviewed our revised surgical strategy for tetralogy of Fallot (TOF) total correction to minimize early exposure to significant pulmonary regurgitation (PR) and to avoid right ventriculotomy (RV-tomy). Methods and Results: Since February 2016, we have tried to preserve, first, pulmonary valve (PV) function to minimize PR by extensive commissurotomy with annulus saving; and second, RV infundibular function by avoiding RV-tomy. With this strategy, we performed total correction for 50 consecutive patients with TOF until May 2018. We reviewed the early outcomes of 27 of 50 patients who received follow-up for ≥3 months. Mean patient age at operation was 10.2±5.0 months, and mean body weight was 8.8±1.2 kg. The preoperative pressure gradient at the RV outflow tract and the PV z-score were improved at most recent echocardiography from 82.0±7.1 to 26.8±6.4 mmHg, and from -2.35±0.49 to -0.55±0.54, respectively, during 11.1±1.6 months of follow-up after operation. One patient required re-intervention for residual pulmonary stenosis. Twenty-two patients had less than moderate PR (none, 1; trivial, 8; mild, 13), and 5 patients had moderate PR. There was no free or severe PR. CONCLUSIONS: At 1-year follow-up, the patients who underwent total TOF correction with our revised surgical strategy had acceptable results in terms of PV function. The preserved PV had a tendency to grow on short-term follow-up.

Comparative Evaluation of Recombinant Human Bone Morphogenetic Protein-2/Hydroxyapatite and Bovine Bone for New Bone Formation in Alveolar Ridge Preservation.

PURPOSE: Hydroxyapatite treated with recombinant human bone morphogenetic protein-2/Hydroxyapatite (rhBMP-2/HA) or bovine bone was applied on extraction sockets for alveolar ridge preservation, and the results were compared with respect to clinical and histological bone formation. MATERIALS AND METHODS: This was a prospective, randomized controlled clinical trial performed on 20 implant placement sites (10 in the experimental and 10 in the control group). rhBMP-2/HA was applied on extraction sockets in the experimental group and bovine bone on those of the control group. The bone at the corresponding sites was biopsied 3 months later, and clinical, histological, and histomorphometric analyses were performed. RESULTS: The alveolar bone height was well preserved in both groups with relatively less change in width in the experimental group compared with the control group. The percentage of new bone was 25.37% ± 17.23% in the experimental group and 6.13% ± 4.32% in the control group; the difference was statistically significant. CONCLUSIONS: The alveolar ridge was preserved clinically and histologically in both groups. rhBMP-2/HA resulted in greater new bone formation than bovine bone 3 months after the surgery.

Effects of Enhanced Hydrophilic Titanium Dioxide-Coated Hydroxyapatite on Bone Regeneration in Rabbit Calvarial Defects.

The regeneration of bone defects caused by periodontal disease or trauma is an important goal. Porous hydroxyapatite (HA) is an osteoconductive graft material. However, the hydrophobic properties of HA can be a disadvantage in the initial healing process. HA can be coated with TiO2 to improve its hydrophilicity, and ultraviolet irradiation (UV) can further increase the hydrophilicity by photofunctionalization. This study was designed to evaluate the effect of 5% TiO2-coated HA on rabbit calvarial defects and compare it with that of photofunctionalization on new bone in the early stage. The following four study groups were established, negative control, HA, TiO2-coated HA, and TiO2-coated HA with UV. The animals were sacrificed and the defects were assessed by radiography as well as histologic and histomorphometric analyses. At 2 and 8 weeks postoperatively, the TiO2-coated HA with UV group and TiO2-coated HA group showed significantly higher percentages of new bone than the control group (p < 0.05). UV irradiation increased the extent of new bone formation, and there was a significant difference between the TiO2-coated HA group and TiO2-coated HA with UV group. The combination of TiO2/HA and UV irradiation in bone regeneration appears to induce a favorable response.

Precise measurement of inner diameter of mono-capillary optic using X-ray imaging technique.

BACKGROUND: Mono-capillary optics have been applied to increase the performance of X-ray instruments. However, performance of a mono-capillary optic strongly depends on the shape accuracy, which is determined by the diameters of the inner hollow of the capillary along the axial direction. OBJECTIVE: To precisely determine the inner diameter of the capillary optic used in X-ray imaging technique, which aims to replace the conventional method using a visible microscope. METHODS: High spatial resolution X-ray images of the mono-capillary optic were obtained by a synchrotron radiation beamline. The inner diameter of the mono-capillary optic was measured and analyzed by the pixel values of the X-ray image. RESULT: Edge enhancement effect was quite useful in determining the inner diameter, and the accuracy of the diameter determination was less than 1.32 µm. Many images obtained by scanning the mono-capillary optic along the axial direction were combined, and the axial profile, consisting of diameters along the axial direction, was obtained from the combined image. The X-ray imaging method could provide an accurate measurement with slope error of±19 µrad. CONCLUSIONS: Applying X-ray imaging technique to determine the inner diameter of a mono-capillary optic can contribute to increasing fabrication accuracy of the mono-capillary optic through a feedback process between the fabrication and measurement of its diameter.

Thermochemical hydrogen sensor based on chalcogenide nanowire arrays.

The hydrogen gas-sensing properties have been investigated of two types of thermochemical hydrogen (TCH) sensors composed of thermoelectric layers based on chalcogenide nanowire arrays and anodic aluminum oxide (AAO) templates. The monomorphic-type TCH sensor, which had only Bi2Te3 nanowire arrays, showed an output signal of 23.7 µV in response to 5 vol% hydrogen gas at room temperature, whereas an output signal of 215 µV was obtained from an n-p junction-type TCH sensor made of connected Bi2Te3 and Sb2Te3 nanowire arrays in an AAO template. Despite its small deposition area, the output signal of the n-p sensor was more than nine times that of the monomorphic sensor. This observation can be explained by the difference in electrical connections (parallel and serial conversions) in the TCH sensor between each type of nanowire array. Also, our n-p sensor had a wide detection range for hydrogen gas (from 400 ppm to 45 vol%) and a fast response time of 1.3 s at room temperature without requiring external power.

Propagation-based phase-contrast X-ray microtomography of a cerebral protection device retrieved after carotid artery stenting.

Phase-contrast synchrotron X-ray microtomography (pcSyncX) based on the highly coherent X-ray beam has previously been used to visualize the microstructures of biologic specimens, but it has never been used to evaluate embolic debris adherent on a cerebral protection device (CPD). The purpose of this study was to demonstrate the feasibility of pcSyncX for evaluating embolic debris during carotid artery stenting (CAS). Five patients (four males, age range 67-77 years) with severe carotid artery stenosis underwent CAS. The retrieved CPD was exposed to synchrotron radiation and 1000 pcSyncX projection images were obtained by rotating the CPD through 180°. An X-ray shadow of a CPD was converted into a visual image by the scintillator. After microtomographic reconstruction, the three-dimensionally reconstructed images were further segmented into the embolic debris and CPD. The total volume of emboli was calculated by summing the volume at each scanning level. The number of membrane pores covered by emboli as seen from the outer surface was counted and the percentage of covered area was calculated. Embolic debris was clearly demonstrated not only on the inner surface and within pores but also on the outer surface of the CPD. The mean total volume of embolic debris was 0.538 × 10(-6) mm(3) (range 0.225-0.965 × 10(-6) mm(3)). Most (61.5%) of the debris was located at the apical one-third of the CPD and 20.8% of the pore area was covered by debris.