SciCombinator

Discover the most talked about and latest scientific content & concepts.

 

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Photoluminescent mechanisms in erbium-doped barium titanate nanoparticle systems were studied. Er3+ ions were introduced into the BaTiO₃ lattice by the sol-gel method. The resulting Er3+ concentration was between 0% and 5%, with Ba/Ti ratios of 1.008 and 0.993. The stoichiometry of Ba and Ti concentrations in the lattice influenced the doping mechanism and placement of erbium ions in the lattice structure. Our research shows the existence of a strong correlation between Ba/Ti ratios, erbium concentration, phase structure and doping site location on the upconversion photoluminescence mechanisms. Competing upconversion emissions ²H11/2/⁴S3/2→⁴I15/2 at 523 and 548 nm respectively and other photoluminescent mechanisms as ⁴I9/2→⁴I11/2 around 4000 nm (2500 cm-1) were studied using Raman and emission spectroscopy. The upconversion process is predominant over other photoluminescent decay when the material presents high distortion in the surrounding activator.

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Reduced therapeutic efficacy of sorafenib, a first-generation multikinase inhibitor, is often observed during the treatment of advanced hepatocellular carcinoma (HCC). Emodin is an active component of Chinese herbs, and is effective against leukemia, lung cancer, colon cancer, pancreatic cancer, and HCC; however, the sensitizing effect of emodin on sorafenib-based HCC therapy has not been evaluated. Here, we demonstrate that emodin significantly improved the anti-cancer effect of sorafenib in HCC cells, such as HepG2, Hep3B, Huh7, SK-HEP-1, and PLC/PRF5. Mechanistically, emodin inhibits sterol regulatory element-binding protein-2 (SREBP-2) transcriptional activity, which suppresses cholesterol biosynthesis and oncogenic protein kinase B (AKT) signaling. Additionally, attenuated cholesterol synthesis and oncogenic AKT signaling inactivated signal transducer and activator of transcription 3 (STAT3), an oncogenic transcription factor. Furthermore, emodin synergistically increased cell cycle arrest in the G1 phase and apoptotic cells in the presence of sorafenib. Animal models xenografted with HepG2 or SK-HEP-1 cells also showed that the combination of emodin and sorafenib was sufficient to inhibit tumor growth. Overall, these results suggested that the combination of emodin and sorafenib may offer a potential therapy for patients with advanced HCC.

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Febrile seizures (FS), events associated with a fever in the absence of an intracranial infection, hypoglycaemia, or an acute electrolyte imbalance, occur in children between six months and six years of age. FS are the most common type of convulsions in children. FS can be extremely frightening for parents, even if they are generally harmless for children, making it important to address parental anxiety in the most sensitive manner. The aim of this review was to focus on the management of FS in the pediatric age. An analysis of the literature showed that most children with FS have an excellent prognosis, and few develop long-term health problems. The diagnosis of FS is clinical, and it is important to exclude intracranial infections, in particular after a complex FS. Management consists of symptom control and treating the cause of the fever. Parents and caregivers are often distressed and frightened after a FS occurs and need to be appropriately informed and guided on the management of their child’s fever by healthcare professionals. Due to the inappropriate use of diagnostic tests and treatments, it is extremely important to improve the knowledge of pediatricians and neurologists on FS management and to standardize the diagnostic and therapeutic work-up.

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Histone deacetylases (HDACs) play a key role in epigenetic mechanisms in health and disease and their dysfunction is implied in several cancer entities. Analysis of expression patterns in pancreatic neuroendocrine tumors (pNETs) indicated HDAC5 to be a potential target for future therapies. As a first step towards a possible treatment, the aim of this study was to evaluate the in vitro cellular and molecular effects of HDAC5 inhibition in pNET cells. Two pNET cell lines, BON-1 and QGP-1, were incubated with different concentrations of the selective class IIA HDAC inhibitor, LMK-235. Effects on cell viability were determined using the resazurin-assay, the caspase-assay, and Annexin-V staining. Western Blot and immunofluorescence microscopy were performed to assess the effects on HDAC5 functionality. LMK-235 lowered overall cell viability by inducing apoptosis in a dose- and time-dependent manner. Furthermore, acetylation of histone-H3 increased with higher LMK-235 concentrations, indicating functional inhibition of HDAC4/5. Immunocytochemical analysis showed that proliferative activity (phosphohistone H3 and Ki-67) decreased at highest concentrations of LMK-235 while chromogranin and somatostatin receptor 2 (SSTR2) expression increased in a dose-dependent manner. HDAC5 expression was found to be largely unaffected by LMK-235. These findings indicate LMK-235 to be a potential therapeutic approach for the development of an effective and selective pNET treatment.

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Increasing evidence suggests that adaptation to diverse environments often involves selection on existing variation rather than new mutations. A previous study identified a nonsynonymous single nucleotide polymorphism (SNP) in exon 2 of two paralogous β-globin genes of the bank vole (Clethrionomys glareolus) in Britain in which the ancestral serine (Ser) and the derived cysteine (Cys) allele represent geographically partitioned functional variation affecting the erythrocyte antioxidative capacity. Here we studied the geographical pattern of the two-locus Ser/Cys polymorphism throughout Europe and tested for the geographic correlation between environmental variables and allele frequency, expected if the polymorphism was under spatially heterogeneous environment-related selection. Although bank vole population history clearly is important in shaping the dispersal of the oxidative stress protective Cys allele, analyses correcting for population structure suggest the Europe-wide pattern is affected by geographical variation in environmental conditions. The β-globin phenotype is encoded by the major paralog HBB-T1 but we found evidence of bidirectional gene conversion of exon 2 with the low-expression paralog HBB-T2. Our data support the model where gene conversion reshuffling genotypes between high- and low- expressed paralogs enables tuning of erythrocyte thiol levels, which may help maintain intracellular redox balance under fluctuating environmental conditions. Therefore, our study suggests a possible role for gene conversion between differentially expressed gene duplicates as a mechanism of physiological adaptation of populations to new or changing environments.

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In spite of all the efforts towards deciphering the silk spinning process of spiders, the underlying mechanism is yet to be fully revealed. In this research, we designed a novel approach that allowed us to quantitatively evaluate the concentration change of silk dope during the liquid-to-solid spinning process of the orb-weaver Nephila pilipes. As a prior characterization of the optimal silking conditions, we first gauged the influence of silking-rate, ranging from 1.5 to 8.0 m/min, on dragline silk diameters and silk tensile strengths obtained from the spiders. Next, to evaluate the liquid content of the silk dope, the major ampullate gland was dissected and the concentration of the sac portion was measured by thermogravimetric analysis (TGA). The solid content of the dragline fibers leaving the spinneret was investigated by calculating the ratio of collected dried silk to the weight loss of the spider recorded in situ upon spinning. As the results indicate, the tensile strength and diameter of the spun dragline fibers were 800⁻1100 MPa and 8⁻11 μm, respectively. The liquid content of silk stored in the major ampullate sac (50.0 wt%) was significantly lower than that of silk leaving the spinnerets (80.9⁻96.1 wt%), indicating that a liquid supplying mechanism might be involved during the spinning process. This reveals, for the first time, quantitative evidence in support of the lubricative hypothesis proposed formerly, namely that a liquid coating layer is supplemented to compensate for silking resistance during the spinning process of a spider. The spigot, at the exit of the spinneret, is speculated to serve as a valve-like controller that regulates the lubrication process along with fiber formation. Taken together, these findings provide understanding of the physiological functions in the spider spinning process and could further shed some light on the future biomimetic development of silk material fabrication.

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The redox pretreatment of samples is one of the crucial ways of altering the catalytic properties of the supported noble metal materials in many heterogeneous reactions. Here, H₂-reducing pretreatment is reported to enhance the thermal stability of Au-CeO₂ catalysts prepared by the deposition⁻precipitation method and calcination at 600 °C for CO oxidation. In order to understand the improved activity and thermal stability, a series of techniques were used to characterize the physico-chemical changes of the catalyst samples. H₂ pretreatment may lead to: (i) a strong metal⁻support interaction (SMSI) between Au nanoparticles (NPs) and CeO₂, evidenced by the particular coverage of Au NPs by CeO₂, electronic interactions and CO adsorption changes. (ii) the production of surface bicarbonates which can accelerate CO oxidation. As a result, the H₂ pretreatment makes the Au NPs more resistant to sintering at high temperature and enhances the CO oxidation activity. Furthermore, this reduction pretreatment strategy may provide a potential approach to enhance the thermal-stability of other supported noble metal catalysts.

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The aim of this study was to explore the reliability and precision of body compartment measures, in particular visceral adipose tissue, in weight stable adults over a range of BMIs using GE-Lunar iDXA. Weight-stable participants aged 18⁻65 years had a total body composition scan on GE-Lunar iDXA either on three separate occasions over a three month period (n = 51), or on a single occasion for duplicate scans with repositioning (n = 30). The coefficient of variation (CV%) and least significant change (LSC) of body compartments were calculated. The CV was higher for all measures over three months (range 0.8⁻5.9%) compared with same-day precision-scans (all < 2%). The CV for visceral adipose tissue (VAT) was considerably higher than all other body compartments (42.2% three months, 16.2% same day scanning). To accurately measure VAT mass using the GE iDXA it is recommended that participants have a BMI ≥ 25 kg/m², or VAT mass > 500 g. Changes observed in VAT mass levels below 500 g should be interpreted with caution due to lack of precision and reliability. All other compartmental measures demonstrated good reliability, with less than 6% variation over three months.

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The purpose of this study is to examine and further understand the effects of post activation potentiation on Achilles tendon (AT) thickness, elasticity and stiffness among basketball players. Basketball is one of the world’s most popular and widely viewed sports. One of the main factors which athletes depend on during their performance is elastic energy coming straight from the AT. Contractile activity increases the muscular force and is known in science as post activation potentiation (PAP). Twelve basketball players (aged 21.3 ± 2.1 years) from the first Polish league took part in this study. The PAP session consisted of single repetitions of the squat with loads corresponding to 60%, 70%, 80%, 90% and 100% of 1 repetition maximum (RM). The measurement method for AT thickness was ultrasonography and for the elasticity and stiffness was myotonometry. The measurements were taken before and immediately after PAP training session. Obtained results: AT stiffness increased significantly from the baseline post exercise, while AT thickness and elasticity decreased after the physical effort. The exercise in PAP caused significant changes in stiffness, elasticity and thickness of the AT.

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A gene cluster, denoted as hcdABC, required for the degradation of 3-(2,4-dihydroxyphenyl)-propionic acid has been cloned from 7-hydroxycoumarin-degrading Pseudomonas mandelii 7HK4 (DSM 107615), and sequenced. Bioinformatic analysis shows that the operon hcdABC encodes a flavin-binding hydroxylase (HcdA), an extradiol dioxygenase (HcdB), and a putative hydroxymuconic semialdehyde hydrolase (HcdC). The analysis of the recombinant HcdA activity in vitro confirms that this enzyme belongs to the group of ipso-hydroxylases. The activity of the proteins HcdB and HcdC has been analyzed by using recombinant Escherichia coli cells. Identification of intermediate metabolites allowed us to confirm the predicted enzyme functions and to reconstruct the catabolic pathway of 3-(2,4-dihydroxyphenyl)-propionic acid. HcdA catalyzes the conversion of 3-(2,4-dihydroxyphenyl)-propionic acid to 3-(2,3,5-trihydroxyphenyl)-propionic acid through an ipso-hydroxylation followed by an internal (1,2-C,C)-shift of the alkyl moiety. Then, in the presence of HcdB, a subsequent oxidative meta-cleavage of the aromatic ring occurs, resulting in the corresponding linear product (2E,4E)-2,4-dihydroxy-6-oxonona-2,4-dienedioic acid. Here, we describe a Pseudomonas mandelii strain 7HK4 capable of degrading 7-hydroxycoumarin via 3-(2,4-dihydroxyphenyl)-propionic acid pathway.