Fluorination of alkylidenecyclopropanes and alkylidenecyclobutanes: divergent synthesis of fluorinated cyclopropanes and cyclobutanes.

A divergent fluorination of alkylidenecyclopropanes (ACPs) and alkylidenecyclobutanes (ACBs) with selectfluor has been achieved. Four different types of products including fluorohydrins, fluoroethers, fluoroesters and fluoroketones could be prepared in moderate to excellent yields. In particular, the cyclopropanes and cyclobutanes were not destroyed during the transformations which involved a radical pathway. The applicability of this method was demonstrated by various transformations of the products.

Dynamic changes in gene expression during follicle development and the efficacy of four timed AI protocols in non-suckling female yaks (Bos grunniens).

The objectives of the study were to investigate changes in the mRNA expression levels of five genes during antral follicle development and to assess the efficacy of four timed-artificial insemination (TAI) protocols in female yaks (Bos grunniens). RT-qPCR analysis revealed that expression levels were greater for follicle-stimulating hormone receptor and bone morphogenic protein 15 in the small follicle, luteinizing hormone receptor, and kit ligand in the large follicle, and growth differentiation factor 9 in the medium follicle (p < 0.05). Non-suckling yaks were treated as a 7-d CIDR, and PGF2α + eCG at CIDR withdrawal and TAI with frozen yak semen at 56-58 h after PGF2α (PPe-7d); either a 7-d CIDR (PPG-7d) or a 5-d CIDR (PPG-5d), and PGF2α at CIDR withdrawal and TAI + GnRH at 70-72 h after PGF2α; and GnRH treatment on Day 0, followed by PGF2α on Day 7 and TAI + GnRH on Day 9 (GPG-7d). The results showed that the pregnancy rate (P/AI) was greater in PPG-5d than in GPG-7d (p < 0.05), but the P/AI was not different among the other TAI protocols. In conclusion, the expression levels of these genes in follicles are dynamically changed during antral follicle development in yaks. The PPG-5d protocol achieved a greater P/AI.

Oxidative functionalization of alkylidenecyclopropanes and alkylidenecyclobutanes: a versatile platform to access nitrated cyclopropanes and cyclobutanes.

A divergent radical nitration of alkylidenecyclopropanes (ACPs) and alkylidenecyclobutanes (ACBs) with Fe(NO3)3·9H2O or AgNO2 has been achieved, affording three categories of products including ß-nitro alcohol, α-nitro ketone and nitro nitratosation products with yields up to 90%. Particularly, the cyclopropyl and cyclobutyl rings were conserved in the products. The applicability of this method was demonstrated by the scale-up experiment and reduction of the nitro into an amino group. Preliminary mechanistic studies suggested that the nitro radical was involved in the reaction process.

Tandem reduction and trifluoroethylation of quinolines and quinoxalines with trifluoroacetic acid and trimethylamine borane.

A metal-free tandem reduction and N-trifluoroethylation of quinolines and quinoxalines has been developed. It provided a convenient route to access trifluoroethylated tetrahydroquinolines and tetrahydroquinoxalines. This one-pot method avoids the purification process of the intermediate. Mechanistically, the in situ-generated boryl acetal species reacted with tetrahydroquinolines to generate iminiums followed by reduction to give the target compounds.

Modulation of DNA conformation in electrolytic nanodroplets.

The behavior of deoxyribonucleic acid (DNA) molecules in confinement is of profound importance in various bioengineering and medical applications. In the present study, all-atom molecular dynamics simulation is utilized to investigate the transition of the double-strand DNA (dsDNA) conformation in the electrolytic nanodroplet. Three typical conformations, i.e., C-shaped, folded S-shaped, and double C-shaped, are observed for different droplet sizes and ionic concentrations. To reveal the physics underlying this phenomenon, the characteristics of the dsDNA molecules, such as the overcharging intensity, the end-to-end distance, the radius of gyration, etc. are analyzed in detail based on the numerical results. It is found that the transition can be ascribed to the buckling of the polymer molecules under the compression due to the confinement of the nanodroplet, and it can be modulated by the ionic concentration in the electrolyte. Generally, nanoscale confinement dominates dsDNA behavior over the electrostatic effects in smaller nanodroplets, while the latter becomes more important for larger nanodroplets. This competition results in the persistence length increasing with the nanodroplet radii. Based on these discussions, a non-dimensional elasto-capillary number µ is proposed to classify the dsDNA conformations into three regions.

Metal-free regioselective nitration of quinoxalin-2(1H)-ones with tert-butyl nitrite.

A metal-free coupling of quinoxalin-2(1H)-ones with tert-butyl nitrite has been developed. Distinctly from the previous functionalization of quinoxalin-2(1H)-ones, this nitration reaction took place selectively at the C7 or C5 position of the phenyl ring, affording a series of 7-nitro and 5-nitro quinoxalin-2(1H)-ones in moderate to good yields. Preliminary mechanistic studies revealed that the reaction may involve a radical process.

[Expressions of SERCA2a and miR-25-3p/5p in myocardium of rats with heart failure and therapeutic effects of Xiefei Lishui recipe].

OBJECTIVE: To investigate the expressions of sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) mRNA and miR-25-3p/5p in myocardium of rats with heart failure and the therapeutic effects of Xiefei Lishui recipe(Traditional Chinese Medicine). METHODS: SD rats were randomly divided into five groups:control group, model group, Traditional Chinese Medicine group(TCM group), captopril group and digoxin group(n=10). Heart failure rat model was induced by intraperitoneal injections of doxorubicin(6 injections within 2 weeks; total dose:15 mg/kg). Five weeks after the first injection, Distilled water(10 ml/(kg·d)), TCM(22 g/(kg·d)), captopril(19 mg/(kg·d)),and digoxin(32µg/(kg·d))were administrated by gastrogavage for 35 days,respectively. Myocardial expressions of SERCA2a mRNA and miR-25-3p/5p were detected;myocardial activities of SERCA2a were measured; cardiac output(CO) and left ventricular ejection fraction(LVEF) and plasma level of B-type natriuretic peptide (BNP) were measured. RESULTS: Myocardial mRNA expression of SERCA2a was significantly down-regulated in rats with heart failure which could be significantly up-regulated by TCM or captopril or digoxin,while expressions of miR-25-3p and miR-25-5p in myocardium were significantly up-regulated which could be significantly down-regulated by TCM or captopril. SERCA2a activity, CO and LVEF in rats with heart failure were decreased significantly which could be significantly increased by TCM,while plasma level of BNP was increased significantly which could be significantly decreased by TCM or captopril or digoxin. CO in rats with heart failure could be signifi-cantly increased by captopril or digoxin. CONCLUSIONS: In rats with heart failure, myocardial mRNA expression of SERCA2a was downregulated, expression of miR-25-3p and miR-25-5p in myocardium was upregulated. Xiefei Lishui recipecan upregulate myocardial mRNA expression of SERCA2a, downregulate expression of miR-25-3p and miR-25-5p in myocardium and improve cardiac function.

[Effect of erythropoietin on reperfusion arrhythmias in rats].

OBJECTIVE: To explore the effect of erythropoietin (EPO) on reperfusion arrhythmias in rats and identify the possible mechanism involved. METHODS: Forty-five SD rats were randomized into a sham-operated group and 4 cardiac ischemia/reperfusion (IR) injury groups, which were further divided into IR group, LY294002 group, EPO group, and EPO+LY294002 group. Cardiac IR injury was induced in the 4 IR injury groups by ligating the left anterior descending branch of the coronary artery (LAD) for 30 min followed by reperfusion for 3 h, with subsequent treatments accordingly. The occurrence of arrhythmias was monitored and scored during experiment, and the levels of serum CK-MB and cTnI were detected. The content of MDA in the myocardium was determined by thiobarbituric acid (TBA) method, and the content of SOD by xanthine oxidase method. RESULTS: The arrhythmia score in EPO group was significantly lower than those in IR, LY294002 and EPO+ LY294002 groups (P<0.05). The levels of serum CK-MB and cTnI were significantly lower in EPO group than in the other 3 IR groups (P<0.001). The EPO group showed also significantly lower MDA content (P<0.001) and higher SOD content than the other 3 IR groups (P<0.001). CONCLUSION: EPO at the dose of 1000 mg/kg decreases the incidence of reperfusion arrhythmias in rats, and this effect can be attenuated by LY294002 pretreatment, suggesting that the cardioprotective effect of EPO involves antioxidation mediated by the phosphoinositide 3-kinase (PI3K) pathway.