Reductive Catalytic Difluorocarbene Transfer via Palladium Catalysis.

A palladium-catalyzed reductive difluorocarbene transfer reaction that tames difluorocarbene to couple with two electrophiles has been developed, representing a new mode of difluorocarbene transfer reaction. The approach uses low-cost and bulk industrial chemical chlorodifluoromethane (ClCF2 H) as the difluorocarbene precursor. It produces a variety of difluoromethylated (hetero)arenes from widely available aryl halides/triflates and proton sources, featuring high functional group tolerance and synthetic convenience without preparing organometallic reagents. Experimental mechanistic studies reveal that an unexpected Pd0/II catalytic cycle is involved in this reductive reaction, wherein the oxidative addition of palladium(0) difluorocarbene ([Pd0 (Ln )]=CF2 ) with aryl electrophile to generate the key intermediate aryldifluoromethylpalladium [ArCF2 Pd(Ln )X], followed by reaction with hydroquinone, is responsible for the reductive difluorocarbene transfer.

Ni-Catalyzed Asymmetric Allylation of Secondary Phosphine Oxides.

A nickel-catalyzed asymmetric allylation of secondary phosphine oxides (SPO) for the synthesis of tertiary phosphine oxides (TPO) was realized with high enantioselectivity. The dynamic kinetic asymmetric transformation of SPO was accomplished in the presence of nickel complex. By elucidating the absolute configurations of the reacted SPO starting material and the TPO product, we confirmed that the allylation reaction proceeded through a P-stereo retention process. The protocol represents the first example of synthesizing P-stereogenic phosphine oxides by allylation reaction.

GABA regulates the proliferation and apoptosis of MAC-T cells through the LPS-induced TLR4 signaling pathway.

Subacute ruminal acidosis (SARA) can cause rapid lipopolysaccharide (LPS) elevation and milk yield decline in lactating ruminants. LPS has been shown to promote apoptosis and reduce the proliferation of mammary epithelial cells. Previous studies have shown that γ- amino butyric acid (GABA) can enhance production performance, regulating ß-cell apoptosis and proliferation. Whether GABA can regulate apoptosis and proliferation induced by LPS in mammary epithelial cells is unknown. In this paper, we detected the role of GABA on proliferation and apoptosis as well as inflammation induced by LPS in bovine mammary epithelial cells (MAC-T cell line). In addition, we explored the role mechanism of GABA in LPS-induced MAC-T cells response through detecting the NFκB signaling pathway key molecules. The results suggested that GABA reduced the effects of cell apoptosis induced by LPS. Furthermore, GABA inhibited the expression of inflammatory cytokines activated by LPS. More importantly, blocking GABA receptors with its antagonist, GABA could not reduce the expression of inflammatory and pro-apoptotic factors activated by LPS. Notably, GABA significantly decreased the TLR4, NFκB p65, and MyD88 mRNA expression levels that were elevated by LPS. Our data indicated that GABA can improve cell viability and decrease apoptosis induced by LPS, while exerting an anti-inflammatory effect through the NFκB signaling pathway.

[Analysis of directional preponderance of caloric test in evaluation of vestibular dynamic compensation].

OBJECTIVE: To analyze the value of directional preponderance (DP) in vestibular dynamic compensation evaluation. METHODS: One hundred fifty-five patients with sudden deafness accompanied vertigo were asked to accept routine vestibular tests including the spontaneous nystagmus (SN) and caloric test with video-nystagmography. DP, SN and unilateral weakness (UW) were selected as the observation parameters. Then the correlation analysis between DP, SN, UW and course of disease were investigated respectively. The change characteristic of the three parameters was also analyzed in the course of vestibular compensation. RESULTS: Of the 155 patients, there were negative correlations between SN, DP and course of disease (r(s) = -0.386, r(s) = -0.424, P < 0.05), positive correlation between SN and DP (r(s) = 0.543, P < 0.05), but no correlation between UW and course of disease (r(s) = 0.004, P > 0.05), and also positive correlation (r(s) = 0.274, P < 0.05) between DP and UW. According to three parameters were positive or negative, three main groups (DP+UW+SN+, DP+UW+SN- and DP-UW+SN-) in DP, UW, SN. The course of disease in three main groups was positively skewed distribution. Median was 6 days, 10 days and 20 days respectively. Through Kruskal-Wallis Test, chi(2) = 24.63, P < 0.05, there was statistical significance among the above three main groups. CONCLUSIONS: DP keeps on changing in the acute stage, static and dynamic compensation stage of peripheral vestibular disease. This indicates that DP can be considered as an objective evaluation index of vestibular dynamic compensation and as a guidance of the vestibular rehabilitation evaluation.