Stereoselective Iron-Catalyzed Alkylation of Enamides with Cyclopropanols via Oxidative C(sp2)-H Functionalization.

Established herein is a radical-mediated C-H alkylation of enamides with cyclopropanols. An environmentally benign catalytic system with iron salt and air is used to permit the oxidative coupling process. The protocol demonstrates a broad substrate scope, allowing the stereoselective synthesis of alkylated enamides. The value of this strategy is further reflected by late-stage diversification of complex cyclopropanol-containing molecules and downstream transformations. Mechanistic studies reveal the dual role of iron salt in the reaction.

Linking oxidative DNA lesion 8-OxoG to tumor development and progression.

Cells of the aerobic metabolic organism are inevitably subjected to the damage from reactive oxygen species (ROS). ROS cause multiple forms of DNA damage, among which the oxidation product of guanine G 8-hydroxyguanine (8-oxoG) is the most frequent DNA oxidative damage, recognized by the specific glycosidase OGG1 that initiates the base excision repair pathway. If left unrepaired, 8-oxoG may pair with A instead of C, leading to a mutation of G: C to T: A during replication. Thus, the accumulation of 8-oxoG or the abnormal OGG1 repair is thought to affect gene function, which in turn leads to the development of tumor or aging-related diseases. However, a series of recent studies have shown that 8-oxoG tends to be produced in regulatory regions of the genome. 8-oxoG can be regarded as an epigenetic modification, while OGG1 is a specific reader of this information. Substrate recognition, binding or resection by OGG1 can cause DNA conformation changes or affect histone modifications, causing up-regulation or down-regulation of genes with different properties. Thus, in addition to the potential genotoxicity, the association of guanine oxidative damage with development of tumors is closely related to its aberrant initiation of gene expression through epigenetic mechanisms. In this review, we summarize the underlying mechanism of 8-oxoG and repair enzyme OGG1 in tumor development and progression, with aims to interpret the relationship between DNA oxidative damage and tumor from a new perspective, and provide new ideas and targets for tumor treatment.

Three-Way Laryngeal Mask Reduces Anesthesia-Related Stress Responses in Bronchoalveolar Lavage: An Experimental Canine Study.

OBJECTIVE: To compare the ventilatory effects of the three-way laryngeal mask airway (TLMA) and tracheal tube (TT) on hemodynamics, respiratory function, and stress responses in a canine model during bronchoalveolar lavage (BAL). STUDY DESIGN: Experimental study. PLACE AND DURATION OF STUDY: The 303rd Hospital of the Chinese People's Liberation Army in May 2013. METHODOLOGY: Sixteen dogs were divided into two groups. MAP, SpO2 and HR were recorded before anesthesia (T0), immediately before intubation (T1), during intubation (T2), at 3 (T3) and 10 (T4) minutes after mechanical ventilation, at 10 (T5), 20 (T6), and 30 (T7) minutes during the course of BAL, during extubation (T8), and 3 minutes after extubation (T9). Tidal volume, peak inspiratory airway pressure, and expiratory CO2 pressure were recorded at time points T2, T5, T6, T7, and T8. Stress responses variables, including epinephrine and norepinephrine levels, were examined at time points T0, T2, T3, T5, T8, and T9. RESULTS: BAL was successfully completed in all animals. In comparison to the TT, the TLMA was capable of maintaining hemodynamic stability and ventilation (p < 0.05), and producing less stress responses (p < 0.05). CONCLUSION: In a canine model, ventilation with the TLMA was better than the TT during BAL in terms of maintaining effective ventilation and stable hemodynamics, and producing less stress responses.

"Turn-off-on" fluorescent sensor for (N-methyl-4-pyridyl) porphyrin -DNA and G-quadruplex interactions based on ZnCdSe quantum dots.

As a new detection model, the reversible fluorescence "turn-off-on" sensor based on quantum dots (QDs) has already been successfully employed in the detections of many biochemical materials, especially in the researches on the interactions between anticancer drugs. The previous studies, however, mainly focused on simple-structured oligonucleotides and Calf thymus DNA. G-quadruplex, an important target for anti-cancer drug with special secondary structure, has been stimulating increasing research interests. In this paper, we report a new detection method based on the fluorescence "turn-off-on" model with water-soluble ZnCdSe QDs as the fluorescent probe, to analyze the interactions between anticancer drug (N-methyl-4-pyridyl) porphyrin (TMPyP) and nucleic acid, especially the G-quadruplex. The fluorescence of QDs can be quenched by TMPyP via photo-induced electron transfer and fluorescence resonance energy transfer, while on the other hand, the combination between TMPyP and G-quadruplex releases QDs from their quenchers and thus recovers the fluorescence. Most importantly, the fluorescence "turn-off-on" model has been employed, for the first time, to analyze the impacts of special factors on the interaction between TMPyP and G-quadruplex. The excellent selectivity of the system has been verified in the studies of the interactions between TMPyP and different DNAs (double-stranded DNA, single-stranded G-quadruplex, and different types of G-quadruplexes) in Na(+) or K(+)-containing buffer.