The catalytic performance of novel water-soluble platinum catalysts modified with various nitrogen-containing and phosphine ligands in the hydrogenation reaction of levulinic acid (LA) into ...γ-valerolactone (GVL) has been studied in environmentally attractive, green, aqueous monophasic systems. The presence of the Lewis acid aluminum enormously increases the catalytic activity of water-soluble platinum catalysts modified with nitrogen-containing ligands in the LA hydrogenation reaction and high catalytic activities up to 3540 TOF’s per hour with a quantitative selectivity towards GVL have been achieved using Na
2
PtCl
6
·6H
2
O precursors modified with the bidentate bathophenanthrolinedisulfonic acid disodium salt (BPhDS) ligand and low amounts of AlCl
3
·6H
2
O promotors (molar ratio of AlCl
3
·6H
2
O/Pt = 0.17) in aqueous media. This unprecedented increase in catalytic activity with aluminum promotors for water-soluble transition metal catalytic systems in aqueous-phase hydrogenation reactions has not been described until now in the literature. The apparent activation energy of platinum catalyst modified with the monodentate nitrilotriacetic acid trisodium salt ligand in aqueous medium was calculated and amounts to a relative low value of 73.04 kJ mol
−1
when one considers that in the LA hydrogenation reaction this catalyst reduces a less reactive keto group into alcohol functionality. A recycling experiment of the Pt/BPhDS/Al catalyst from the aqueous monophasic LA hydrogenation reaction mixture followed by biphasic recovery of the catalyst in active form from organic reaction products by extraction and simple phase separation of an aqueous/organic two-phase system formed after addition of diethyl ether has shown that the Pt/BPhDS/Al catalyst is stable without loss of activity and selectivity in a consecutive run.
Graphical Abstract
High catalytic activities (TOF = 8680 h
−1
) have been achieved by novel rhodium catalysts modified with the chelating sulfonated phosphite ligand hexasulfonated
o
-phenylendiphosphite in the ...hydrogenation reaction of renewable methyl esters of sunflower oil under mild reaction conditions and a low rhodium concentration of 50 ppm in methanol.
Graphical Abstract
Objective: The investigation of intentional behavior of hospital staff to care for COVID-19 patients and the study of the factors that influences it. Method: This is a cross-sectional study, of 261 ...physicians and nurses working in a COVID-19 reference hospital. Data were collected by an anonymous questionnaire including demographic and professional characteristics and a scale measuring behavioral intention based on the Theory of Planned Behavior of Ajzen. Statistical analysis was performed by SPSS 21. Results: Mean age of participants was 40.8 years old, while most of them were nurses (75.7%). Behavioral intention mean score was 18.2 (5–21), which shows high intention to care for COVID-19 patients. Bivariate analysis between independent variables showed that behavioral intention mean score was higher for those that had cared for COVID-19 patients and those that did not (19.0% vs. 16.7%, p < 0.001). Multivariate linear regression analysis identified that increased subjective norms (the perceived social pressure to perform or not the behavior) score was associated with increased behavioral intention score (p < 0.001). Also, participants that provided care for COVID-19 patients had higher behavioral intention score (p < 0.001). Conclusion: Healthcare staff, that cared for COVID-19 patients had high behavioral intention to continue caring for them. This finding could be used to inform policies and training for staff that will be employed in COVID-19 units.
Background
Hyaluronic acid (HA) has been found to be an important trigger of atherosclerosis. In this study, we investigate the possible association of serum HA with cardiovascular disease risk in a ...population of low/intermediate risk for cardiovascular events.
Methods
We enrolled 200 subjects with low/intermediate risk for developing cardiovascular disease. High specific C‐reactive protein (hsCRP) was used as an indicator of preclinical atherosclerosis. The Framingham score was used to calculate the cardiovascular risk.
Results
Participants with dyslipidemia had significantly higher levels of serum HA than those without dyslipidemia (t‐test, P = 0.05), higher levels of hsCRP (Kruskal–Wallis test, P = 0.04), and higher cardiovascular risk according to the Framingham score (Kruskal–Wallis test, P = 0.05). Serum HA concentration correlated significantly with the Framingham score for risk for coronary heart disease over the next 10 years (Spearman r = 0.152, P = 0.02). Diabetic volunteers had significantly higher HA than those without diabetes (t‐test, P = 0.02). Participants with metabolic syndrome had higher serum HA levels and higher hsCRP (Kruskal–Wallis test, P = 0.01) compared to volunteers without metabolic syndrome (t‐test, P = 0.03).
Conclusions
Serum HA should be explored as an early marker of atheromatosis and cardiovascular risk.
Studies on the serum concentration of hyaluronic acid (HA) in newly diagnosed patients with acute myeloid leukemia (AML), B-acute lymphoblastic leukemia (B-ALL), and mantle-cell lymphoma (MCL) are ...scarce. In this study, we focused on investigating whether HA could serve as a possible prognostic marker in patients with AML, B-ALL, and MCL.
The serum concentration of HA was measured in a total of 51 patients with newly diagnosed AML, B-ALL, and MCL. Venous blood was collected 1 day before the initiation of chemotherapy (D0), on day 16 of the first cycle of chemotherapy (D16), and on D30.
The serum HA concentration on D0 in patients with AML, B-ALL, and MCL was higher than in the control group. For all types of hematological malignancy, on D0, serum HA values of nonsurvivors were higher than in survivors. Moreover, patients in relapse had higher levels of serum HA than patients in remission. A strong positive correlation between serum HA and ferritin, β2-microglobulin, and lactate dehydrogenase was found.
Serum HA may serve as a possible prognostic marker for AML, B-ALL, and MCL patients, especially on D0. Prospective case-control studies on larger populations may provide further information.
Gemcitabine (2′,2′-difluoro-2′-deoxycytidine), a widely used anticancer drug, is considered a gold standard in treating aggressive pancreatic cancers. Gamma-proteobacteria that colonize the ...pancreatic tumors contribute to chemoresistance against gemcitabine by metabolizing the drug to a less active and deaminated form. The gemcitabine transporters of these bacteria are unknown to date. Furthermore, there is no complete knowledge of the gemcitabine transporters in Escherichia coli or any other related proteobacteria. In this study, we investigate the complement of gemcitabine transporters in E. coli K-12 and two common chemoresistance-related bacteria (Klebsiella pneumoniae and Citrobacter freundii). We found that E. coli K-12 has two high-affinity gemcitabine transporters with distinct specificity properties, namely, NupC and NupG, whereas the gemcitabine transporters of C. freundii and K. pneumoniae include the NupC and NupG orthologs, functionally indistinguishable from their counterparts, and, in K. pneumoniae, one additional NupC variant, designated KpNupC2. All these bacterial transporters have a higher affinity for gemcitabine than their human counterparts. The highest affinity (KM 2.5–3.0 μΜ) is exhibited by NupGs of the bacteria-specific nucleoside-H+ symporter (NHS) family followed by NupCs (KM 10–13 μΜ) of the concentrative nucleoside transporter (CNT) family, 15–100 times higher than the affinities reported for the human gemcitabine transporter hENT1/SLC29A1, which is primarily associated with gemcitabine uptake in the pancreatic adenocarcinoma cells. Our results offer a basis for further insight into the role of specific bacteria in drug availability within tumors and for understanding the structure–function differences of bacterial and human drug transporters.
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•Ancestral reconstruction is used to study evolution of the XanQ permease specificity.•XanQ may have originated from a broad-specificity xanthine/guanine permease.•The orthologs from ...beta-proteobacteria have retained the xanthine/guanine profile.•The non-binding-site mutation S377G is sufficient to broaden the XanQ specificity.•The specificity of XanQ has been shaped by few changes outside the binding site.
The relation of sequence with specificity in membrane transporters is challenging to explore. Most relevant studies until now rely on comparisons of present-day homologs. In this work, we study a set of closely related transporters by employing an evolutionary, ancestral-reconstruction approach and reveal unexpected new specificity determinants. We analyze a monophyletic group represented by the xanthine-specific XanQ of Escherichia coli in the Nucleobase-Ascorbate Transporter/Nucleobase-Cation Symporter-2 (NAT/NCS2) family. We reconstructed AncXanQ, the putative common ancestor of this clade, expressed it in E. coli K-12, and found that, in contrast to XanQ, it encodes a high-affinity permease for both xanthine and guanine, which also recognizes adenine, hypoxanthine, and a range of analogs. AncXanQ conserves all binding-site residues of XanQ and differs substantially in only five intramembrane residues outside the binding site. We subjected both homologs to rationally designed mutagenesis and present evidence that these five residues are linked with the specificity change. In particular, we reveal Ser377 of XanQ (Gly in AncXanQ) as a major determinant. Replacement of this Ser with Gly enlarges the specificity of XanQ towards an AncXanQ-phenotype. The ortholog from Neisseria meningitidis retaining Gly at this position is also a xanthine/guanine transporter with extended substrate profile like AncXanQ. Molecular Dynamics shows that the S377G replacement tilts transmembrane helix 12 resulting in rearrangement of Phe376 relative to Phe94 in the XanQ binding pocket. This effect may rationalize the enlarged specificity. On the other hand, the specificity effect of S377G can be masked by G27S or other mutations through epistatic interactions.
γ-Valerolactone (GVL) is a key downstream product of renewable biomass with enormous potential for the manufacture of advanced biofuels, bio-based chemicals, materials or for its direct use as an ...additive to gasoline and is obtained by the hydrogenation reaction of the important platform molecule levulinic acid (LA). Unprecedented high catalytic activities (TOF = 42530 h−1) have been achieved by water-dispersible ruthenium nanoparticles (RuNPs) stabilized by a broad spectrum of water-soluble polymers with both oxygen-containing functionalities such as the non-toxic and inexpensive polyethylene glycol (PEG) and poly(vinyl alcohol) (PVA) and with polymers bearing nitrogen-groups in the hydrogenation of LA to obtain with high selectivities (99.2 mol%) GVL in the aqueous medium. Furthermore, water provides for a desired higher dispersion of RuNPs catalysts capable to achieve high activities and impressive stabilities. The calculated apparent activation energy of the RuNPs/PEG catalyst amounts a low value of 32.3 kJ/mol. TEM investigations revealed the formation of RuNPs/PVA catalysts with a small average particle size diameter of 2.8 ± 0.1 nm which is consistent with the high catalytic activities. Recycling experiments have shown that the RuNPs/PVA catalyst demonstrated superb stability and selectivity in five consecutive runs at a high molar ratio LA/Ru = 16000 which is of industrial interest.
The Roma, known as well as gypsies, constitute the largest transnational, non-territorial nation. Research has indicated that the majority of Roma students cannot meet school requirements. Teachers' ...attributions on the causes of Roma students' underachievement have focused on factors such as poverty, illiteracy and different values system. Consequently, developmental factors associated with Roma students' achievement have been understudied. The aims of this study were to investigate within the Greek context if teachers' judgments with the use of an appropriate screening tool can detect Roma students at risk for developmental disabilities and predict their actual language achievement. The study participants were 82 Greek primary school students; 43 Roma students and 39 non-Roma students. The Greek version of the Learning Disabilities Diagnostic Inventory (LDDI) was used as the screening tool. Greek language achievement was assessed through a non-standardized curriculum-based test. Main findings revealed that, according to teachers' judgments, both Roma and non-Roma students were at risk for developmental disabilities; both groups earned low scores on the language achievement test, particularly Roma students; and teachers' judgments had predictive accuracy on students' language achievement. Research findings highlight the need for the universal assessment and differential diagnosis of culturally and linguistically diverse students.
The catalytic performance of novel water-soluble platinum catalysts modified with various nitrogen-containing and phosphine ligands in the hydrogenation reaction of levulinic acid (LA) into ...gamma-valerolactone (GVL) has been studied in environmentally attractive, green, aqueous monophasic systems. The presence of the Lewis acid aluminum enormously increases the catalytic activity of water-soluble platinum catalysts modified with nitrogen-containing ligands in the LA hydrogenation reaction and high catalytic activities up to 3540 TOF's per hour with a quantitative selectivity towards GVL have been achieved using Na.sub.2PtCl.sub.6·6H.sub.2O precursors modified with the bidentate bathophenanthrolinedisulfonic acid disodium salt (BPhDS) ligand and low amounts of AlCl.sub.3·6H.sub.2O promotors (molar ratio of AlCl.sub.3·6H.sub.2O/Pt = 0.17) in aqueous media. This unprecedented increase in catalytic activity with aluminum promotors for water-soluble transition metal catalytic systems in aqueous-phase hydrogenation reactions has not been described until now in the literature. The apparent activation energy of platinum catalyst modified with the monodentate nitrilotriacetic acid trisodium salt ligand in aqueous medium was calculated and amounts to a relative low value of 73.04 kJ mol.sup.-1 when one considers that in the LA hydrogenation reaction this catalyst reduces a less reactive keto group into alcohol functionality. A recycling experiment of the Pt/BPhDS/Al catalyst from the aqueous monophasic LA hydrogenation reaction mixture followed by biphasic recovery of the catalyst in active form from organic reaction products by extraction and simple phase separation of an aqueous/organic two-phase system formed after addition of diethyl ether has shown that the Pt/BPhDS/Al catalyst is stable without loss of activity and selectivity in a consecutive run. Graphical
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