The multichannel i-propyl + O2 reaction system: A model of secondary alkyl radical oxidation

The i-propyl + O2 reaction mechanism has been investigated by definitive quantum chemical methods to establish this system as a benchmark for the combustion of secondary alkyl radicals. Focal point analyses extrapolating to the ab initio limit were performed based on explicit computations with electron correlation treatments through coupled cluster single, double, triple, and quadruple excitations and basis sets up to cc-pV5Z. The rigorous coupled cluster single, double, and triple excitations/cc-pVTZ level of theory was used to fully optimize all reaction species and transition states, thus, removing some substantial flaws in reference geometries existing in the literature. The vital i-propylperoxy radical (MIN1) and its concerted elimination transition state (TS1) were found 34.8 and 4.4 kcal mol-1 below the reactants, respectively. Two β-hydrogen transfer transition states (TS2, TS2') lie above the reactants by (1.4, 2.5) kcal mol-1 and display large Born-Oppenheimer diagonal corrections indicative of nearby surface crossings. An α-hydrogen transfer transition state (TS5) is discovered 5.7 kcal mol-1 above the reactants that bifurcates into equivalent α-peroxy radical hanging wells (MIN3) prior to a highly exothermic dissociation into acetone + OH. The reverse TS5 → MIN1 intrinsic reaction path also displays fascinating features, including another bifurcation and a conical intersection of potential energy surfaces. An exhaustive conformational search of two hydroperoxypropyl (QOOH) intermediates (MIN2 and MIN3) of the i-propyl + O2 system located nine rotamers within 0.9 kcal mol-1 of the corresponding lowest-energy minima.

A hyaluronic acid modified cuprous metal-organic complex for reversing multidrug resistance via redox dyshomeostasis

Multidrug resistance (MDR) which is often related to the overexpression of P-glycoprotein (P-gp) in drug-resistant cancer cells has been a major problem faced by current cancer chemotherapy. Reversing P-gp-related MDR by disrupting tumor redox homeostasis that regulates the expression of P-gp is a promising strategy. In this work, a hyaluronic acid (HA) modified nanoscale cuprous metal-organic complex (HA-CuTT) was developed to reverse P-gp-related MDR via two-way regulated redox dyshomeostasis, which was achieved by both Cu⁺-catalyzed generation of •OH and disulfide bonds-mediated depletion of glutathione (GSH). In vitro studies reveal that the DOX-loaded complex (HA-CuTT@DOX) has excellent targeting ability to HepG2-ADR cells due to the modification of HA and effectively induces redox dyshomeostasis in HepG2-ADR cells. Moreover, HA-CuTT@DOX can cause mitochondrial damage, decrease ATP level, and downregulate the P-gp expression, thereby leading to the reversal of MDR and the increased drug accumulation in HepG2-ADR cells. Importantly, in vivo experimental results show that it can achieve effective inhibition (89.6 %) of tumor growth in nude mice bearing HepG2-ADR cells. This is the first work to reverse P-gp-related MDR via two-way regulated redox dyshomeostasis based on a HA modified nanoscale cuprous metal-organic complex, providing a new therapeutic paradigm for effective treatment of MDR-related cancer.

A GLUTs/GSH cascade targeting-responsive bioprobe for the detection of circulating tumor cells

A GLUTs/GSH cascade targeting-responsive bioprobe, GluCC, was rationally designed and synthesized for the first time via the coordination of copper ions with a glucose-modified coumarin derivative ligand (GluC). GluCC can specifically detect circulating tumor cells (CTCs) in lung metastatic mice models by targeting the Warburg effect and responding to overexpressed glutathione in the tumor microenvironment. This bioprobe with a simple detection procedure has significant advantages for CTC detection.

Mechanism for the Reaction of White Phosphorus with Cp2Cr2(CO)6 Leading Ultimately to the Triple-Decker Sandwich Cp2Cr2(μ-η5,η5-P5): A Theoretical Study

The experimentally known reaction of Cp₂Cr₂(CO)₆ with white phosphorus (P₄) to give CpCr(CO)₂(η³-P₃), Cp₂Cr₂(CO)₄(μ-η,²η²-P₂), and the triple-decker sandwich Cp₂Cr₂(μ-η,⁵η⁵-P₅) is of interest since the P₄ reactant having a tetrahedral cluster of four phosphorus atoms is converted to products having P₂, P₃, and P₅ ligands. The mechanism of this obviously complicated reaction can be dissected into three stages using a coupled cluster theoretical method that has been benchmarked with the P₂, Mn(CO)₅, and CpCr(CO)₃ dimerization processes. The first stage of the Cp₂Cr₂(CO)₆/P₄ reaction mechanism generates the unsaturated singlet intermediate Cp₂Cr₂(CO)₅ that combines with the P₄ reactant. Decarbonylation of the resulting Cp₂Cr₂(CO)₅(P₄) complex provides a singlet tetracarbonyl readily fragmenting into the stable triphosphacyclopropenyl complex CpCr(CO)₂(η³-P₃) and the chromium phosphide CpCr(CO)₂(P). The isomeric triplet tetracarbonyl Cp₂Cr₂(CO)₄(P₄), readily fragments into CpCr(CO)₂(η²-P₂), which can generate the stable diphosphaacetylene complex Cp₂Cr₂(CO)₄(η,²η²-P₂) as well as the pentamer [CpCr(CO)₂]₅(P₁₀). Combination of the coordinately unsaturated CpCr(CO)(η³-P₃) with CpCr(CO)₂(η²-P₂) can lead to a ring expansion. This generates the P₅ pentagonal ligand in a Cp₂Cr₂(CO)₃(P₅) precursor to the experimentally observed carbonyl-free triple-decker sandwich Cp₂Cr₂(μ-η,⁵η⁵-P₅) after three successive decarbonylations.

The dual role of anti-viral therapy in the treatment of Coronavirus disease 2019

OBJECTIVE

Coronavirus disease 2019 (COVID-19) has become a worldwide public health emergency; unfortunately, there is currently no treatment for improving outcomes or reducing viral-clearance times in infected patients. The aim of the present study was to evaluate the efficacy of interferon (IFN) with or without lopinavir and ritonavir as antiviral therapeutic option for treating COVID-19 infection.

PATIENTS AND METHODS

The present study enrolled 148 patients that received either standard care, treatment with IFN alfa-2b, or IFN alfa-2b combined with lopinavir plus ritonavir. Viral testing was performed using Reverse-Transcription Polymerase Chain Reaction (RT-PCR).

RESULTS

There was no significant difference in the viral-clearance time at 28 days after treatment between patients receiving standard care and those receiving anti-viral treatments. However, the average viral-clearance time of patients receiving standard care (14 days) was shorter than that for patients receiving IFN alfa-2b or IFN alfa-2b combined with lopinavir plus ritonavir (15.5 or 17.5 days) (p<0.05). Patients treated with IFN alfa-2b within five days or IFN alfa-2b combined with lopinavir plus ritonavir after three days of symptoms exhibited shorter viral-clearance times than the other groups (p<0.05). Moreover, viral-clearance times were significantly longer in patients receiving standard care or anti-viral treatment 5 days after symptoms appeared than those of patients who received these treatments within five days of symptom onset (p<0.05).

CONCLUSIONS

Early symptomatic treatment is most critical for maximizing amelioration of COVID-19 infection. Anti-viral treatment might have complicated effect on viral-clearance.

Tumor microenvironment responsive supramolecular glyco-nanovesicles based on diselenium-bridged pillar[5]arene dimer for targeted chemotherapy

Supramolecular glyco-nanovesicles (SeSe-(P5)2⊃Man-NH3+) based on the host-guest complex of a diselenium-bridged pillar[5]arene dimer and a mannose derivative have been successfully developed for the first time, which possessed tumor microenvironment-responsiveness and specific targetability due to their diselenium bonds and mannose units, respectively.

P2S2-Bridged binuclear metal carbonyls from dimerization of coordinated thiophosphoryl groups: a theoretical study

Theoretical studies indicate the complexes M(CO)_n(PS) with bent 1-e/2-e donor PS groups to be unstable for giving the stable M(CO)_n−1(PS) with linear 3-e donor PS groups. In addition, only Mn₂(CO)₈(P₂S₂) is energetically viable from the Mn(CO)₄(PS).

Understanding the singlet–triplet energy splittings in transition metal-capped carbon chains

Density functional theory and molecular orbital analysis suggest that the odd–even alternation of singlet–triplet energy separations is a general feature of transition metal-capped carbon chains, determined primarily by the carbon chains.

Most favorable cumulenic structures in iron-capped linear carbon chains are short singlet odd-carbon dications: a theoretical view

DFT computations suggest that the odd iron-capped linear-carbon dications exhibit large ΔE_S–T values and more cumulenic structures than short even-carbon chains.

The Prognostic Significance of Soluble Programmed Death Ligand 1 Expression in Cancers: A Systematic Review and Meta-analysis

The differential expression of soluble programmed death ligand 1 (sPD-L1) has been found in some cancers; however, the correlation between sPD-L1 expression and prognosis value in tumour is still unclear. Here, we conducted a meta-analysis and systematic review to assess the prognostic value of sPD-L1 in patients with cancer. Eligible studies were searched for in the databases including PubMed, Web of Science, ScienceDirect and Wiley Online Library database. The pooled hazard ratios (HRs) with a 95% confidence interval (95%CI) were calculated to assess the prognostic significance of sPD-L1 in human cancer. Eight studies and 1102 patients with cancer were included in the final analysis, and the combined analysis indicated that a higher level of sPD-L1 was associated with worse overall survival (OS) (HR = 1.60, 95%CI: 1.21-1.99). Furthermore, statistical significance was also observed in subgroup analysis stratified by the cancer type (haematological neoplasms or non-haematological neoplasms), sample size (more or less than 100), cut-off value of sPD-L1 (more or less than 6.51 ng/ml) and ethnicity (Asian or European). The meta-analysis indicates that circulating sPD-L1 changes may serve as a useful biomarker for cancer prognosis, and higher level of sPD-L1 may also be associated with poor outcomes in patients with cancer.

Heavier Carbon Subchalcogenides as C3 Sources for Tungsten-Capped Cumulenes: A Theoretical Study

Heavier carbon subchalcogenides C₃E₂ (E = S, Se) can bind to transition metals through either a C═C or a C═E double bond. These two binding modes on a reactive tungsten (PMe₃)₄WCl₂ site have been explored by density functional theory methods (M06-L/DZP+Lanl2DZ). The important step controlling the reaction direction is the initial binding of the C₃E₂ ligand. Of particular significance is the M═C═C═C═E fragment resulting from the C═E coordination mode. This fragment can bind to additional C₃E₂ molecules or bridge to other metals. Ultimately C₃E₂ serves as a source of C₃ units for building C_3n carbon sp-hybridized allotropes.

mRNA and protein expression levels of four candidate genes for ear size in Erhualian and Large White pigs

Porcine ear size is an important characteristic for distinguishing among pig breeds. In a previous genome-wide association study of porcine ear size, LEM domain-containing 3 (LEMD3), methionine sulfoxide reductase B3 (MSRB3), high mobility group AT-hook 2 (HMGA2), and Wnt inhibitory factor 1 (WIF1) were implicated as important candidate genes for ear size. This study investigated the expression levels of four candidate genes for ear size in Erhualian and Large White pigs. Ten Erhualian pigs with large ears and eight Large White pigs with small ears at 60 days of age were examined. The mRNA expression levels of the four candidate genes were quantified by real-time polymerase chain reaction. WIF1 mRNA expression was significantly higher in Large White than in Erhualian pigs (P < 0.05), whereas the expression levels of the other three genes were not significantly different between the two breeds. The protein expression levels of the four genes were analyzed using western blot. WIF1 protein expression was significantly higher in Large White than in Erhualian pigs (P < 0.01), whereas MSRB3 protein expression was significantly higher in Erhualian than in Large White pigs (P < 0.05). There were no significant differences between the two breeds in residual protein expression. These results suggest that WIF1 is the main causal gene for ear size in pigs.

[Expression and clinical significance of HMGA2 in renal carcinoma]

Objective: To detect the high mobility group A2 (HMGA2) expression in renal carcinoma, and to explore the relationship with clinicopathological features and its significance for prognosis. Methods: 50 renal carcinoma specimens, 50 corresponding adjacent normal kidney tissue samples, and 40 benign renal tumor specimens were used in this study. The expressions of HMGA2 mRNA and protein were detected by RT-PCR, Western blot and immunohistochemical assays, and its relationship with clinicopathological features and prognosis in the renal carcinoma patients was analyzed. Results: The RT-PCR results showed that the relative expression levels of HMGA2 mRNA in the renal carcinoma, benign renal tumor tissues, and adjacent normal renal tissues were 0.84±0.23, 0.19± 0.06 and 0.08±0.04, respectively, and the expression in renal carcinoma tissue was significantly higher than those of the other 2 groups (P<0.01). The Western blot results showed that the relative expression levels of HMGA2 protein in the renal carcinoma, benign renal tumor tissues, and adjacent normal renal tissues were 0.91±0.24, 0.12±0.04 and 0.03±0.01, respectively, and the expression in renal carcinoma tissue was significantly higher than those of the other 2 groups (P<0.01). Immunohistochemical results showed that the expression of HMGA2 protein exhibited brown and tan granular, which mainly distributed in the cell nuclei. Among the 50 cases of renal carcinoma, 34 cases exhibited positive expression, with a positive rate of 68.0%. Among the 40 cases of benign tumor tissues, 3 cases had positive expression, with a positive rate of 7.5%, while among the 50 cases of adjacent normal renal tissues, there was only 1 case exhibiting positive expression of HMGA2 protein, with a positive rate of 2.0%. The protein expression of HMGA2 was significantly higher in the renal carcinoma than in the benign tumors and normal renal tissues (P=0.004). There was no statistically significant difference in the association of HMGA2 protein expressions with age, sex, tumor size and histological type (P>0.05), while significant difference did exist in the association with different statuses of TNM staging and lymph node metastasis (P<0.05). The median time to progression (TTP) in 34 HMGA2 protein-positive patients was (22.36±1.48) months and that of 16 HMGA2 protein-negative patients was (34.55±1.87) months (P<0.05). Conclusions: HMGA2 plays an important role in the tumorigenesis and development of renal carcinoma, and may be used as an important predictor for estimating the prognosis of renal carcinoma. HMGA2 might become a new diagnostic and prognostic marker for renal carcinoma.

Porcine MAP3K5 analysis: molecular cloning, characterization, tissue expression pattern, and copy number variations associated with residual feed intake

Mitogen-activated protein kinase kinase kinase 5 (MAP3K5) is essential for apoptosis, proliferation, differentiation, and immune responses, and is a candidate marker for residual feed intake (RFI) in pig. We cloned the full-length cDNA sequence of porcine MAP3K5 by rapid-amplification of cDNA ends. The 5451-bp gene contains a 5'-untranslated region (UTR) (718 bp), a coding region (3738 bp), and a 3'-UTR (995 bp), and encodes a peptide of 1245 amino acids, which shares 97, 99, 97, 93, 91, and 84% sequence identity with cattle, sheep, human, mouse, chicken, and zebrafish MAP3K5, respectively. The deduced MAP3K5 protein sequence contains two conserved domains: a DUF4071 domain and a protein kinase domain. Phylogenetic analysis showed that porcine MAP3K5 forms a separate branch to vicugna and camel MAP3K5. Tissue expression analysis using real-time quantitative polymerase chain reaction (qRT-PCR) revealed that MAP3K5 was expressed in the heart, liver, spleen, lung, kidney, muscle, fat, pancrea, ileum, and stomach tissues. Copy number variation was detected for porcine MAP3K5 and validated by qRT-PCR. Furthermore, a significant increase in average copy number was detected in the low RFI group when compared to the high RFI group in a Duroc pig population. These results provide useful information regarding the influence of MAP3K5 on RFI in pigs.

Anhydrides-Cured Bimodal Rubber-Like Epoxy Asphalt Composites: From Thermosetting to Quasi-Thermosetting

The present engineering practices show the potential that epoxy asphalt composites (EACs) would be a better choice to obtain long life for busy roads. To understand the service performance–related thermorheological properties of prepared bimodal anhydrides-cured rubber-like EACs (REACs), a direct tensile tester, dynamic shear rheometer and mathematical model were used. Tensile tests demonstrate that all the REACs reported here are more flexible than previously reported anhydrides-cured REACs at both 20 and 0 °C. The better flexibility is attributed to the change of bimodal networks, in which cross-linked short chains decreased and cross-linked long chains increased, relatively. Strain sweeps show that all the REACs have linear viscoelastic (LVE) properties when their strains are smaller than 1.0% from −35 to 120 °C. Temperature sweeps illustrate that the thermorheological properties of REACs evolve from thermosetting to quasi-thermosetting with asphalt content, and all the REACs retain solid state and show elastic properties in the experimental temperature range. A Cole–Cole plot and Black diagram indicate that all the REACs are thermorheologically simple materials, and the master curves were constructed and well-fitted by the Generalized Logistic Sigmoidal models. This research provides a facile approach to tune the thermorheological properties of the REACs, and the cheaper quasi-thermosetting REAC facilitates their advanced applications.

Molecular cloning, tissue expression pattern, and copy number variation of porcine SCUBE3

The signal peptide CUB EGF-like domain-containing protein 3 (SCUBE3) gene is a member of SCUBE gene family and plays important roles in bone cell biology and the determination of limb bone length. In this study, the full-length transcript of porcine SCUBE3 was cloned using reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends. The full-length sequence of porcine SCUBE3 cDNA was 4131 base pairs and included 21 exons. The SCUBE3 gene contained a 2895-base pair open reading frame that encoded a peptide of 965 amino acids. Comparison of the deduced amino acid sequences of porcine SCUBE3 with those of human, mouse, zebrafish, and rat showed 96, 95, 73, and 95% identities, respectively. Porcine SCUBE3 mRNA expression levels were highest in the backfat, bone marrow, and cartilage tissues. Copy number variation was detected in porcine SCUBE3 and validated by real-time quantitative polymerase chain reaction. Different copy number variations were present in randomly selected individuals and may, therefore, be a good marker for identifying phenotypic traits. Our findings provide a basis for further investigation of the functions and regulatory mechanisms of SCUBE3 in pigs.

Differences between carbon suboxide and its heavier congeners as ligands in transition metal complexes: a theoretical study

The lowest energy structures for the [M](C₃E₂) complexes ([M] = Ir, Ni, Pt surrounded by ligands such as phosphines and halides; E = O, S, Se) are compared.

Cleavage of carbon suboxide to give ketenylidene and carbyne ligands at a reactive tungsten site: a theoretical mechanistic study

The reaction of (MePPh₂)₄WCl₂ with C₃O₂ results in stepwise cleavage of the two CC double bonds in C₃O₂ to give tungsten complexes containing phosphinoketenylidene and phosphinocarbyne ligands. The mechanism of this has been elucidated using density functional theory.

In Vivo Antioxidant Properties of Lotus Root and Cucumber: A Pilot Comparative Study in Aged Subjects

OBJECTIVES

To compare the effects of lotus root and cucumber on antioxidant function in aged subjects.

DESIGN

Pilot comparative study.

SETTING

Research setting with vegetable intervention.

PARTICIPANTS

Healthy aged subjects over the age of sixty.

INTERVENTION

30-day supplementation of lotus root or cucumber powder.

MEASUREMENTS

Plasma value of ferric reducing antioxidant power assay, activity of antioxidant enzymes, contents of some antioxidants, oxidation products, hemolysis, blood mononuclear cell DNA damage and urinary excretion of 8-hydroxy-2'-deoxyguanosine were measured before and after the intervention.

RESULTS

Plasma glutathione peroxidase activity, contents of vitamin C, total phenolics were significantly increased, while plasma uric acid content significantly decreased in both groups at the end of the intervention. Meanwhile, hemolysis was significantly reduced in both groups and DNA injury rate of blood mononuclear cells in lotus root group and the ratio of comet tail length to total length in cucumber group were also declined significantly post-intervention. However, plasma value of ferric reducing antioxidant power assay, contents of reduced glutathione, vitamin E, malondialdehyde, oxidized low density lipoprotein, carbonyls and activity of superoxide dismutase and catalase were not changed significantly in both group after the intervention.

CONCLUSION

These results suggest that lotus root and cucumber are not remarkably different in improving antioxidant function in aged subjects, though they are significantly different in antioxidant capacity in vitro. The benefits observed in this study may come from the additive or synergistic combinations of antioxidants contained in vegetables.

Pathways to the polymerization of boron monoxide dimer to give low-density porous materials containing six-membered boroxine rings

Density functional theory has been used to examine the key mechanistic details of the polymerization of boron monoxide (BO) via its O≡B-B≡O dimer to give ultimately low-density porous polymeric (BO)n materials. The structures of such materials consist of planar layers of six-membered boroxine (B3O3) rings linked by boron-boron bonds. Initial cyclooligomerization of B2O2 leads to a B4O4 dimer with a four-membered B2O2 ring, a B6O6 trimer containing a six-membered B3O3 (boroxine) ring, a B8O8 tetramer containing an eight-membered B4O4 ring, and even a B10O10 pentamer containing a ten-membered B5O5 ring. However, an isomeric B10O10 structure containing two boroxine rings linked by a B-B bond is a much lower energy structure by ∼31 kcal/mol owing to the special stability of the aromatic boroxine rings. Rotation of the boroxine rings around the central B-B bond in this B10O10 structure has a low rotation barrier suggesting that further oligomerization to give products containing either perpendicular or planar orientations of the B3O3 rings is possible. However, the planar oligomers are energetically more favorable since they have fewer high-energy external BO groups bonded to the network of boroxine rings. The pendant boronyl groups are reactive sites that can be used for further polymerization. Mechanistic aspects of the further oligomerization of (BO)x systems to give a B24O24 oligomer with a naphthalene-like arrangement of boroxine rings and a B84O84 structure with a coronene-like arrangement of boroxine rings have been examined. Further polymerization of these intermediates by similar processes is predicted to lead ultimately to polymers consisting of planar networks of boroxine rings. The holes between the boroxine rings in such polymers suggests that they will be porous low-density materials. Applications of such materials as absorbents for small molecules are anticipated.

The siliconyl, boronyl, and iminoboryl ligands as analogues of the well-known carbonyl ligand: predicted reactivity towards dipolar cyclooligomerization in iron/cobalt carbonyl complexes

The Fe(CO)₄(SiO), Co(CO)₄(BO), and Co(CO)₄(BNSiMe₃), complexes akin to the well-known Fe(CO)₅ are predicted by density functional theory to undergo exothermic oligomerization to give the oligomers containing Si_nO_n/B_nO_n/B₂N₂ rings with single bonds.

The facile coupling of carbon monochalcogenides to ethenedichalcogenone ligands in binuclear iron carbonyl derivatives: a theoretical study

The lowest energy Fe₂(CO)_n(CE)₂ structures (E = S, Se, Te; n = 7, 6) do not have separate CE ligands but instead have coupled C₂E₂ ligands functioning as four to six-electron donors to the pair of iron atoms.

Molecular characteristics of the MHC-DRA genes from yak (Bos grunniens) and Chinese yakow (Bos grunniens × Bos taurus)

Two full-length cDNAs (762 bp) of the DRA gene from yak and Chinese yakow were isolated and analysed to identify structural and functional variations. The sequences for DRA in yak (Bogr-DRA) and Chinese yakow (Bogr × BoLA-DRA) were essentially identical to those for cattle (99%) and buffalo (97%). Except for two substitutions in the amino acids comprising the domain for signal peptide (SP) in yak, the additional residues were highly conserved across the species investigated. Peptide-binding site (PBS) of Bogr-DRA and Bogr × BoLA-DRA was highly reserved in the α1 domain among all species investigated. The lack of mutation in Bogr-DRA is consistent with the conception that the gene is highly conserved among all mammalian species. The very high conservation of the DRA gene among ruminants, including yak, may be due to its recent evolutionary detachment.