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•High specific surface area TiO2 nanotube powders were fabricated by anodization of porous titanium.•TiO2 nanotube powders with a coral-structure surface, and the maximum specific ...surface reached 280 m2/g.•Porous titanium as an anodic substrate enhances the reaction rate and promotes the shedding of nanotube fragments.•High-frequency cyclic anodization increases reaction yield effectively.
The specific surface area of TiO2 powders is an important factor affecting the performance. In this study, we present a simple and novel method to fabricate TiO2 nanopowders based on electrochemical anodization. TiO2 nanopowders with coral-like structure surface and maximum specific surface area of 280 m2/g were fabricated in an aqueous electrolyte containing 1 M Na2SO4 and 0.5 wt% NaF under applied potential of 10 V. Porous titanium as an anodic substrate enhances the reaction rate and promotes the shedding of nanotube fragments. The reaction yield of powders prepared at high-frequency 10 V is nearly 3.7 times higher than that prepared at constant potential 10 V. The specific surface area of the powder prepared at high-frequency-15 V is 61% higher than that prepared at constant potential 15 V.
P-type ATPases are a large family of enzymes that actively transport ions across biological membranes by interconverting between high (E1) and low (E2) ion-affinity states; these transmembrane ...transporters carry out critical processes in nearly all forms of life. In striated muscle, the archetype P-type ATPase, SERCA (sarco(endo)plasmic reticulum Ca2+-ATPase), pumps contractile-dependent Ca2+ ions into the lumen of sarcoplasmic reticulum, which initiates myocyte relaxation and refills the sarcoplasmic reticulum in preparation for the next contraction. In cardiac muscle, SERCA is regulated by phospholamban (PLB), a small inhibitory phosphoprotein that decreases the Ca2+ affinity of SERCA and attenuates contractile strength. cAMP-dependent phosphorylation of PLB reverses Ca2+-ATPase inhibition with powerful contractile effects. Here we present the long sought crystal structure of the PLB-SERCA complex at 2.8-Å resolution. The structure was solved in the absence of Ca2+ in a novel detergent system employing alkyl mannosides. The structure shows PLB bound to a previously undescribed conformation of SERCA in which the Ca2+ binding sites are collapsed and devoid of divalent cations (E2-PLB). This new structure represents one of the key unsolved conformational states of SERCA and provides a structural explanation for how dephosphorylated PLB decreases Ca2+ affinity and depresses cardiac contractility.
Background: Phospholamban (PLB) regulates sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) activity and is thus a key regulator of cardiac contractility.
Results: We present the crystal structure of SERCA in complex with PLB at 2.8-Å resolution.
Conclusion: PLB stabilizes a divalent cation-free conformation of SERCA with collapsed Ca2+ binding sites. We call the structure E2-PLB.
Significance: The E2-PLB structure explains how PLB decreases Ca2+ affinity and depresses cardiac contractility.
Abstract
Hemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening condition in children with sepsis. We herein aimed to identify clinical and laboratory predictors of HLH in ...children with sepsis. We conducted a retrospective study of 568 children with sepsis admitted to Guangdong Women and Children Hospital from January 2019 to June 2022. HLH, while rare (6.34%), proved to be a highly fatal complication (37.14%) in children with sepsis. Children with HLH had higher levels of aspartate aminotransferase, lactate dehydrogenase, triglycerides, and ferritin than children without HLH; conversely, they displayed decreased levels of neutrophils, hemoglobin, platelets, fibrinogen, and albumin. Additionally, the HLH group showed higher rates of prolonged fever (> 10 days), hepatomegaly, and splenomegaly than the non-HLH group. Our retrospective analysis identified hypofibrinogenemia (OR = 0.440,
P
= 0.024) as an independent predictor for the development of HLH in patients with sepsis. The optimal cutoff value for fibrinogen was found to be < 2.43 g/L. The area under the curve for diagnosing HLH was 0.80 (95% confidence interval: 0.73–0.87,
P
< 0.0001), with a sensitivity of 72.41% and specificity of 76.27%. Thus, hypofibrinogenemia emerges as a potentially valuable predictor for HLH in children with sepsis.
Renal sympathetic denervation (RD) is a promising method of neuromodulation for the management of cardiac arrhythmia.
We tested the hypothesis that RD is antiarrhythmic in ambulatory dogs because it ...reduces the stellate ganglion nerve activity (SGNA) by remodeling the stellate ganglion (SG) and brain stem.
We implanted a radiotransmitter to record SGNA and electrocardiogram in 9 ambulatory dogs for 2 weeks, followed by a second surgery for RD and 2 months SGNA recording. Cell death was probed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.
Integrated SGNA at baseline and 1 and 2 months after RD were 14.0 ± 4.0, 9.3 ± 2.8, and 9.6 ± 2.0 μV, respectively (P = .042). The SG from RD but not normal control dogs (n = 5) showed confluent damage. An average of 41% ± 10% and 40% ± 16% of ganglion cells in the left and right SG, respectively, were TUNEL positive in RD dogs compared with 0% in controls dogs (P = .005 for both). The left and right SG from RD dogs had more tyrosine hydroxylase-negative ganglion cells than did the left SG of control dogs (P = .028 and P = .047, respectively). Extensive TUNEL-positive neurons and glial cells were also noted in the medulla, associated with strongly positive glial fibrillary acidic protein staining. The distribution was heterogeneous, with more cell death in the medial than lateral aspects of the medulla.
Bilateral RD caused significant central and peripheral sympathetic nerve remodeling and reduced SGNA in ambulatory dogs. These findings may in part explain the antiarrhythmic effects of RD.
Abstract Aims Phospholamban (PLB) regulates the cardiac Ca 2 + -ATPase (SERCA2a) in sarcoplasmic reticulum (SR). However, the localization of PLB at subcellular sites outside the SR and possible ...contributions to Ca 2 + cycling remain unknown. We examined the intracellular distribution of PLB and tested whether a pool of PLB exists in the nuclear envelope (NE) that might regulate perinuclear/nuclear Ca 2 + (nCa 2 + ) handling in cardiomyocytes (CMs). Methods and results Using confocal immunofluorescence microscopy and immunoblot analyses of CMs and CM nuclei, we discovered that PLB was highly concentrated in NE. Moreover, the ratio of PLB levels to SERCA levels was greater in NE than in SR. The increased levels of PLB in NE were a consistent finding using a range of antibodies, tissue samples, and species. To address a possible role in affecting Ca 2 + handling, we used Fluo-4 based confocal Ca 2 + imaging, with scan-lines across cytosol and nuclei, and evaluated the effects of PLB on cytosolic and nCa 2 + uptake and release in mouse CMs. In intact CMs, isoproterenol increased amplitude and decreased the decay time of Ca 2 + transients not only in cytosol but also in nuclear regions. In saponin-permeabilized mouse CMs (Ca 2 + i = 400 nM), we measured spontaneous Ca 2 + waves after specific reversal of PLB activity by addition of the Fab fragment of an anti-PLB monoclonal antibody (100 μg/ml). This highly selective immunological reagent enhanced Ca 2 + uptake (faster decay times) and Ca 2 + release (greater intensity) in both cytosol and across the nuclear regions. Conclusions Besides SR, PLB is concentrated in NE of CMs, and may be involved in modulation of nCa 2 + dynamics.
The relationships among intestinal dysbiosis, bile acid (BA) metabolism disorders, and ulcerative colitis pathogenesis are now recognized. However, how specific strains regulate BA metabolism to ...alleviate colitis is still unclear. This study investigated the effects of
on the development of acute colitis and elucidated the underlying mechanisms.
The safety of BDX-01 was evaluated
and
. 2.5% dextran sulfate sodium (DSS) induced colitis in C57BL/6 mice, Caco-2, and J774A.1 cells were used to evaluate the anti-inflammatory effect of BDX-01. qPCR and Western blotting were used to detect the expression of inflammatory pathways. Microbiota composition was analyzed by 16S rRNA gene sequencing. Enzyme activity analysis and targeted metabolomics were used to analyze fecal bile salt hydrolase (BSH) and BA levels. Antibiotic-induced pseudo-germ-free mice were used to investigate the role of gut microbiota in the alleviation of colitis by BDX-01.
We confirmed the safety of novel strain
BDX-01
and
. Oral BDX-01 administration significantly ameliorated the symptoms and pathological damage of DSS-induced acute colitis. Moreoever, 16S rRNA sequencing and enzyme activity analysis showed that BDX-01 treatment increased intestinal BSH activity and the abundance of bacteria harboring this enzyme. Targeted metabolomics revealed that BDX-01 significantly increased intestinal BA excretion and deconjugation. Certain BAs act as FXR agonists. The β-muricholic acid (βMCA): taurine β-muricholic acid (T-βMCA) and cholic acid (CA): taurocholic acid (TCA) ratios and the deoxycholic acid (DCA) level decreased markedly in the colitis models but increased substantially in BDX-01-treated mice. The colonic farnesoid X receptor (FXR) and fibroblast growth factor 15 (FGF15) were upregulated in mice treated with BDX-01. BDX-01 downregulated the expression of colonic proinflammatory cytokines pyrin domain-containing 3 (NLRP3), ASC, cleaved caspase-1, and IL-1β. Antibiotic treatment didn't abolish the protective effect of BDX-01 on colitis.
studies showed TβMCA abolished the effects of BDX-01 on FXR activation and inhibition of the NLRP3 inflammasome activation.
BDX-01 improved DSS-induced acute colitis by regulating intestinal BSH activity and the FXR-NLRP3 signaling pathway. Our findings indicate that BDX-01 is a promising probiotic to improve the management of ulcerative colitis.
Fusarium head blight is a destructive disease of grains resulting in reduced yields and contamination of grains with mycotoxins worldwide; Fusarium graminearum is its major causal agent. Chromatin ...structure changes play key roles in regulating mycotoxin biosynthesis in filamentous fungi. Using a split-marker approach in three F. graminearum strains INRA156, INRA349 and INRA812 (PH-1), we knocked out the gene encoding H2A.Z, a ubiquitous histone variant reported to be involved in a diverse range of biological processes in yeast, plants and animals, but rarely studied in filamentous fungi. All ΔH2A.Z mutants exhibit defects in development including radial growth, sporulation, germination and sexual reproduction, but with varying degrees of severity between them. Heterogeneity of osmotic and oxidative stress response as well as mycotoxin production was observed in ΔH2A.Z strains. Adding-back wild-type H2A.Z in INRA349ΔH2A.Z could not rescue the phenotypes. Whole genome sequencing revealed that, although H2A.Z has been removed from the genome and the deletion cassette is inserted at H2A.Z locus only, mutations occur at other loci in each mutant regardless of the genetic background. Genes affected by these mutations encode proteins involved in chromatin remodeling, such as the helicase Swr1p or an essential subunit of the histone deacetylase Rpd3S, and one protein of unknown function. These observations suggest that H2A.Z and the genes affected by such mutations are part or the same genetic interaction network. Our results underline the genetic plasticity of F. graminearum facing detrimental gene perturbation. These findings suggest that intergenic suppressions rescue deleterious phenotypes in ΔH2A.Z strains, and that H2A.Z may be essential in F. graminearum. This assumption is further supported by the fact that H2A.Z deletion failed in another Fusarium spp., i.e., the rice pathogen Fusarium fujikuroi.
The effects of intermittent open-loop vagal nerve stimulation (VNS) on the ventricular rate (VR) during atrial fibrillation (AF) remain unclear.
The purpose of this study was to test the hypothesis ...that VNS damages the stellate ganglion (SG) and improves VR control during persistent AF.
We performed left cervical VNS in ambulatory dogs while recording the left SG nerve activity (SGNA) and vagal nerve activity. Tyrosine hydroxylase (TH) staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were used to assess neuronal cell death in the SG.
We induced persistent AF by atrial pacing in 6 dogs, followed by intermittent VNS with short ON-time (14 seconds) and long OFF-time (66 seconds). The integrated SGNA and VR during AF were 4.84 mV·s (95% confidence interval CI 3.08-6.60 mV·s) and 142 beats/min (95% CI 116-168 beats/min), respectively. During AF, VNS reduced the integrated SGNA and VR, respectively, to 3.74 mV·s (95% CI 2.27-5.20 mV·s; P = .021) and 115 beats/min (95% CI 96-134 beats/min; P = .016) during 66-second OFF-time and to 4.07 mV·s (95% CI 2.42-5.72 mV·s; P = .037) and 114 beats/min (95% CI 83-146 beats/min; P = .039) during 3-minute OFF-time. VNS increased the frequencies of prolonged (>3 seconds) pauses during AF. TH staining showed large confluent areas of damage in the left SG, characterized by pyknotic nuclei, reduced TH staining, increased percentage of TH-negative ganglion cells, and positive TUNEL staining. Occasional TUNEL-positive ganglion cells were also observed in the right SG.
VNS damaged the SG, leading to reduced SGNA and better rate control during persistent AF.
Background:
Small-conductance Ca
2+
-activated K
+
channels (SK channels) have been proposed as antiarrhythmic targets for the treatment of atrial fibrillation. We previously demonstrated that the ...5-HT
3
receptor antagonist ondansetron inhibits heterologously expressed, human SK2 (hSK2) currents as well as native cardiac SK currents in a physiological extra-/intracellular K
+
gradient at therapeutic (i.e., sub-micromolar) concentrations. A recent study, using symmetrical K
+
conditions, challenged this result. The goal of the present study was to revisit the inhibitory effect of ondansetron on hSK2-mediated currents in symmetrical K
+
conditions.
Experimental Approach:
The whole-cell patch clamp technique was used to investigate the effects of ondansetron and apamin on hSK2-mediated currents expressed in HEK 293 cells. Currents were measured in symmetrical K
+
conditions in the presence of 100 nM Ca
2+
o
.
Results:
Expression of hSK2 produced inwardly rectifying whole-cell currents in the presence of 400 nM free cytosolic Ca
2+
. Ondansetron inhibited whole-cell hSK2 currents with
IC
50
values of 154 and 113 nM at −80 and 40 mV, respectively. Macroscopic current inhibited by ondansetron and current inhibited by apamin exhibited inwardly rectifying current-voltage relationships with similar reversal potentials (apamin, ∼5 mV and ondansetron, ∼2 mV). Ondansetron (1 μM) in the continuing presence of apamin (100 nM) had no effect on hSK2-mediated whole-cell currents. Wild-type HEK 293 cells did not express ondansetron- or apamin-sensitive currents.
Conclusion:
Ondansetron in sub-micromolar concentrations inhibits hSK2 currents even under altered ionic conditions.
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