Preventive and therapeutic effect of N-Acetyl-L-cysteine on infection-associated preterm labor in mice

Objective:To study the preventive and therapeutic effect of N-Acetyl-L-cysteine on infectionassociated preterm labor in mice.Methods:A total of 66 C57BL/6 inbred strain pregnant mice were selected and randomly divided into groups A,B and C,with 22 cases in each group.Group A,B and C were regarded as model group,prevention group and treatment group,respectively.The model of infection-associated preterm labor was built by intraperitoneal injection of Escherichia coli.Ten mice of each group were taken and observed the preterm birth rates and live birth rates,respectively.Three mice of each group were killed at 3 h,6 h,12 h and 24 h after building the model.Their uterus tissues were collected and the expressions of the AP-1 and MCP-1 in those tissues were assayed with immunohistochemical method and the expressions of NF-κ Bp65 and TNF- protein in the placenta tissues of those mice were also detected with immunohistochemical method.Results:The preterm birth rates of mice in groups B and C were significantly lower than that in group A,while their live birth rates were distinctly higher than that in group A(P<0.05);the expressions of the AP-1 and MCP-1 in the uterus tissues and NF-κ Bp65 and TNF- protein in the placenta tissues of mice in groups B and C were evidently lower than those in group A(P<0.05);the comparison of the expressions of the NF-κ Bp65 and TNF- between group B and C showed no statistical differences(P>0.05).Conclusions:N-Acetyl-L-cysteine can lower the incidence rate of infection-associated preterm labor by prohibiting the activation of the protein AP-1/MCP-1and decreasing the expression of NF- κ Bp65 and TNF- in the pregnant tissues of premature mice to reduce the inflammatory reactions.

New N-acetyl-L-cysteine derivatives synthesized by the degradation of proanthocyanidins as high biological activity antioxidants

A novel degradation method was investigated to synthesize highly biologically active flavan-3-ol derivatives in the presence of N-acetyl-L-cysteine(NAC)as a nucleophile under acidic conditions for polymerized proanthocyanidins degradation.The reaction conditions were optimized by the combination of single-factor test and central composite experimental design(CCD).Grape seed proanthocyanidins were reacted with NAC at a ratio of 1:3 with 0.3 M methanolic HC1,a temperature of 55°C,and a reaction time of 50 mins.Most of the degradation products were separated and prepared by one-step high-speed countercurrent chromatography(HSCCC)and preparative high-performance liquid chromatography(prep-HPLC).Three monomeric pro anthocyanidins and four new N-acetyl-L-cysteine derivatives were isolated from degradation products with total degradation yield of 55.44%and high purity over 95%.Furthermore,the neuroprotective abilities of these compounds to H2O2-treated PC-12 neuroblastoma cells were evaluated.NAC derivatives showed better antioxidant activity than their corresponding underivatized monomers and NAC,indicating that they had a better performance in protecting PC-12 cells from oxidative stress damage.

PDMS Microchip Capillary Electrophoresis for Determination of Thiol Compounds

A fast and sensitive method for the determination of thiol compounds including homocysteine, glutathione and N-aeetyl-l-cysteine using microchip capillary electrophoresis was proposed. The mierochip was made from an elastomerie material-poly （dimethylsiloxane） （PDMS）. The microehip configureation consists of a top layer of PDMS containing of injection and separation channels, reservoirs and a gold microwire sealed with a bottom layer of PDMS. A gold microwire was used as the working electrode and platinum mierowire was used as counter electrode. The pulsed amperometric detection （PAD） was applied for determination of these thiol compounds. The experiments were carried out with 20 mM MES and 1 mM SDS buffer （pH 6.0）. In order to optimize the conditions, detection and separation potential, pH buffer, injection time, and PAD parameters were studied. Homocysteine, glutathione and N-aeetyl-L-cysteine can be separated and detected in less than 2 rain at the detection potential of ＋0.8 V, separation potential of ＋1200 V, and injection time of 20 s, with good reproducibility and sensitivity.

Effect of Alteration of Glutathione Content on Cell Viability in α-Synuclein-Transfected SH-SY5Y Cells

It is well known that α-synuclein (αS) plays an important role in the pathogenesis of Parkinson’s disease (PD). Moreover, oxidative stress is also thought to be an important factor in PD due to induction of dopaminergic neuronal cell death by free radicals and enhancement of αS fibrillation by oxidized stress. In the present study, to clarify the role of glutathione (GSH), an intracellular antioxidant, on the molecular mechanism of αS-induced cell injury, we examined the effects of L-buthionine-SR-sulfoximine (BSO), a GSH synthase inhibitor, with or without N-acetyl-L-cysteine (NAC), a source of GSH, on αS-induced cell injury in human neuroblastoma SH-SY5Y cells. Treatment with BSO significantly reduced the cell viability of both empty-vector- and αS-transfected SH-SY5Y cells in a dose-dependent manner (p < 0.01), although the ratio of αS-induced reduction of cell viability in α-syn-transfected cells was much greater than that in empty-vector-transfected cells. Moreover, BSO significantly reduced the intracellular total GSH level in both types of transformant cells. However, NAC significantly prevented BSO-induced reduction of both cell viability and GSH level in the αS-transfected cells. These findings suggest that GSH plays an important role in αS-induced cell injury by reducing cell viability.

Repair of dysfunctional bone marrow endothelial cells alleviates aplastic anemia

Aplastic anemia(AA)is a life-threatening disease characterized by bone marrow(BM)failure and pancytopenia.As an important component of the BM microenvironment,endothelial cells(ECs)play a crucial role in supporting hematopoiesis and regulating immunity.However,whether impaired BM ECs are involved in the occurrence of AA and whether repairing BM ECs could improve hematopoiesis and immune status in AA remain unknown.In this study,a classical AA mouse model and VE-cadherin blocking antibody that could antagonize the function of ECs were used to validate the role of BM ECs in the occurrence of AA.Nacetyl-L-cysteine(NAC,a reactive oxygen species scavenger)or exogenous EC infusion was administered to AA mice.Furthermore,the frequency and functions of BM ECs from AA patients and healthy donors were evaluated.BM ECs from AA patients were treated with NAC in vitro,and then the functions of BM ECs were evaluated.We found that BM ECs were significantly decreased and damaged in AA mice.Hematopoietic failure and immune imbalance became more severe when the function of BM ECs was antagonized,whereas NAC or EC infusion improved hematopoietic and immunological status by repairing BM ECs in AA mice.Consistently,BM ECs in AA patients were decreased and dysfunctional.Furthermore,dysfunctional BM ECs in AA patients led to their impaired ability to support hematopoiesis and dysregulate T cell differentiation toward proinflammatory phenotypes,which could be repaired by NAC in vitro.The reactive oxygen species pathway was activated,and hematopoiesis-and immune-related signaling pathways were enriched in BM ECs of AA patients.In conclusion,our data indicate that dysfunctional BM ECs with impaired hematopoiesis-supporting and immunomodulatory abilities are involved in the occurrence of AA,suggesting that repairing dysfunctional BM ECs may be a potential therapeutic approach for AA patients.

Role of oxygen free radicals in the proliferation of myofibroblasts induced by AngII

Previous studies have demonstrated the important role of angiotension II(AngII)in promoting proliferation of myofibroblasts(myoFbs)and myocardial fibrosis.However,the underlying mechanisms and the role of oxygen free radicals in the proliferation of myofibroblasts induced by AngII are unclear.The present study was designed to shed light on this issue through exploration of AngII signaling pathways via in vitro experiments.Primary cultures of neonatal rat myoFbs were divided into five groups which were treated with AngII(10^(-8) to 10^(-6) M),AngII with the antioxidant N-acetyl-L-cysteine(NAC),or normal culture medium.We observed the proliferation of myoFbs as induced by AngII at different concentrations with MTT.Reactive oxygen species(ROS)levels in myoFbs were detected by monitoring the fluorescence of 2',7'-dichlorofluorescein.The contents and levels of oxygen free radicals(OH·)in the three groups were detected by spectrophotometer,immunocytochemical staining,and confocal fluorescence.Western blot and image analysis were used to measure membrane translocation and expression of phospho-protein kinase Ca.MyoFbs incubated with AngII(10^(-8) to 10^(-6) M)for 24 h increased their rate of proliferation,the content of OH·,and expression of ROS(P<0.01 vs.control group),whereas these parameters decreased in the presence of NAC.Immunocytochemistry,confocal fluorescence staining and image analysis showed that AngII could promote the translocation and expression of p-PKCα in membrane,and the antioxidant NAC blocked this increase(P<0.01).Western blot results also showed that NAC could inhibit the expression of p-PKCα.