Exendin-4 protects murine MIN6 pancreatic β-cells from interleukin-1β-induced apoptosis via the NF-κB pathway

BACKGROUND

Glucagon-like peptide-1 (GLP-1) and its potent analog, exendin-4, are well known to inhibit β- cell apoptosis and promote β-cell proliferation. Meanwhile, cytokines, such as interleukin-1β (IL-1β), stimulate inducible nitric oxide synthase (iNOS) expression and nitric oxide overproduction leading to β-cell damage. However, the protective mechanisms of GLP-1 in β-cells exposed to cytokines have not been fully elucidated.

AIMS

In this study, the protective effects of exendin-4 on IL-1β-induced apoptosis were investigated in murine MIN6 pancreatic β-cells. The role of nuclear factor-κB (NF-κB) signaling in this process was also explored.

METHODS

The effects of exendin-4 pre-treatment on IL-1β-induced apoptosis were investigated by Hoechst/PI and Annexin V/PI staining. Levels of iNOS and NF-κB proteins were investigated by Western blotting and cytoplasmic nitrite levels were determined using Griess reagent.

RESULTS

IL-1β treatment (range, 5-40 ng/ml) for 24 h was positively correlated with nitrite production (R2=0.9668, p<0.01), a significant increase in the percentage of apoptotic cells (p<0.01) and a concomitant dose-dependent increase in cytoplasmic levels of iNOS and NF-κB p65 activation. N-acetyl- L-cysteine (NAC), NG-nitro-L-arginine methyl ester (L-NAME) and pyrrolidine dithiocarbamate (PDTC), partially rescued apoptotic β-cells, suggesting involvement of NF-κB-iNOS-nitrite in this process. Exendin-4 (100 nM) treatment significantly decreased IL-1β-induced apoptosis (p<0.01), downregulated NF-κB activation and subsequently decreased iNOS and nitrite levels in IL-1β-induced β-cells (p<0.001), in a similar manner to L-NAME, PDTC and NAC.

CONCLUSIONS

These results suggest that exendin-4 protects against IL-1β- induced apoptosis in β-cells via downregulation of the NF- κB-iNOS-nitrite pathway.

DLJ14, a novel chemo-sensitization agent, enhances therapeutic effects of adriamycin against MCF-7/A cells both in vitro and in vivo

OBJECTIVES

We investigated the chemo-sensitization of a ligustrazine derivate, (E)-2-(2, 4-dimethoxystyryl)-3, 5, 6-trimethylpyrazine (DLJ14) on Adriamycin (Adr, Wanle, Shenzhen, China)-resistant human breast cancer (MCF-7/A) cells both in vivo and in vitro.

METHODS

The antitumour effects of DLJ14 and Adr was observed in MCF-7/A cells by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay in vitro and was evaluated by MCF-7/A xenografts in nude mice. The intracellular Adr accumulation was assessed by mean fluorescence intensity of Adr. The messenger RNA level of glutathione (GSH) S-transferase (GST)π in MCF-7/A cells was determined by real-time reverse transcription PCR assay. The expression of GSTπ, c-jun NH2 -terminal kinase (JNK) and phosphor-JNK (p-JNK) was detected by Western blotting method.

KEY FINDINGS

The MTT results showed that DLJ14 exhibited a weak inhibition on proliferation of both MCF-7 and MCF-7/A cells, in contrast with the strong inhibition of verapamil. When DLJ14 is combined with Adr, the inhibitory effect on MCF-7/A cells and MCF-7/A xenografts was enhanced significantly through increasing intracellular accumulation of Adr by inhibition of GSH level and the activity of GSH peroxidase and GST. Moreover, DLJ14 could downregulate the expression of GSTπ and increase the expression of JNK and p-JNK in MCF-7/A cells or in xenografts.

CONCLUSION

DLJ14 is a promising chemo-sensitization candidate for the reversal of multidrug resistance in cancers.

Involvement of Src tyrosine kinase and protein kinase C in the expression of macrophage migration inhibitory factor induced by H2O2 in HL-1 mouse cardiac muscle cells

Macrophage migration inhibitory factor (MIF), a pleiotropic cytokine, plays an important role in the pathogenesis of atrial fibrillation; however, the upstream regulation of MIF in atrial myocytes remains unclear. In the present study, we investigated whether and how MIF is regulated in response to the renin-angiotensin system and oxidative stress in atrium myocytes (HL-1 cells). MIF protein and mRNA levels in HL-1 cells were assayed using immunofluorescence, real-time PCR, and Western blot. The result indicated that MIF was expressed in the cytoplasm of HL-1 cells. Hydrogen peroxide (H₂O₂), but not angiotensin II, stimulated MIF expression in HL-1 cells. H₂O₂-induced MIF protein and gene levels increased in a dose-dependent manner and were completely abolished in the presence of catalase. H₂O₂-induced MIF production was completely inhibited by tyrosine kinase inhibitors genistein and PP1, as well as by protein kinase C (PKC) inhibitor GF109203X, suggesting that redox-sensitive MIF production is mediated through tyrosine kinase and PKC-dependent mechanisms in HL-1 cells. These results suggest that MIF is upregulated by HL-1 cells in response to redox stress, probably by the activation of Src and PKC.

Antitumour effect of sesquiterpene (+)-chabranol on four human cancer cell lines by inducing apoptosis and autophagy

OBJECTIVE

To investigate the effects and mechanisms of sesquiterpene (+)-chabranol on proliferation of a panel of four human tumour cell lines (BGC-823, SGC-7901, SSMC-7721 and HepG2).

METHODS

Cell viability was assessed using a standard methyltetrazolium assay; cell-cycle analysis of BGC-823 cells was performed by flow cytometry. Transmission electron microscopy (TEM) was used to examine the ultrastructure of BGC-823 cells exposed to (+)-chabranol. Apoptosis was investigated by evaluating DNA laddering, using gel electrophoresis.

RESULTS

(+)-Chabranol had a marked time- and concentration-dependent inhibitory effect on BGC-823 cell proliferation. The effect was less marked in SGC-7901, SSMC-7721 and HepG2 cells. Exposure of BGC-823 cells to (+)-chabranol arrested the cell cycle at G(1). Evidence of apoptosis and autophagy was observed by TEM; DNA laddering in BGC-823 cells supported the presence of apoptosis.

CONCLUSIONS

This study suggested that (+)-chabranol has antitumour activity against BGC-823 cells, and may exert its action by inhibition of proliferation and induction of apoptosis and autophagy. With further development, (+)-chabranol may represent a potential novel treatment for poorly differentiated gastric cancer.

[Research progress of dual inhibitors targeting HIV-1 reverse transcriptase and integrase]

Both reverse transcriptase (RT) and integrase (IN) play crucial roles in the life cycle of HIV-1, which are also key targets in the area of anti-HIV drug research. Reverse transcriptase inhibitors are involved in the most employed drugs used to treat AIDS patients and HIV-infected people, while one of the integrase inhibitors has already been approved by US FDA to appear on the market. Great achievement has been made in the research on both, separately. Recently, much more attention of medicinal chemistry researchers has been attracted to the strategies of multi-target drugs. Compounds with excellent potency against both HIV RT and IN, evidently defined as dual inhibitors targeting both enzymes, have been obtained through considerable significant exploration, which can be classified into two categories according to different strategies. Combinatorial chemistry approach together with high throughput screening methods and multi-target-based virtual screening strategy have been useful tools for identifying selective anti-HIV compounds for long times; Rational drug design based on pharmacophore combination has also led to remarkable results. In this paper, latest progress of both categories in the discovery and structural modification will be covered, with a view to contribute to the career of anti-HIV research.

[The application of structural optimization strategies in drug design of HIV NNRTIs]

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) play an important roles in the prevention and treatment of AIDS. NNRTIs can specifically target at HIV reverse transcriptase (RT) and have the advantages of high potency and low toxicity, which make them a research focus for a long time. In the guidance of structural optimization strategies (bioisosterism, molecular hybridization and scaffold hopping) in medicinal chemistry, structural modification to lead compounds can be carried out to design new compounds with different levels, which will improve the efficiency of drug discovery and decrease the cost of drug development. It is an effective way to find new NNRTIs. In this review, we will expatiate on the application of different levels of structural optimization strategies in the NNRTIs structural modification with concrete examples.

Pinellia pedatisecta agglutinin interacts with the methylosome and induces cancer cell death

Pinellia pedatisecta agglutinin (PPA) is a specific mannose-binding plant lectin accumulated in the tuber of P. pedatisecta. In the work presented, the cytotoxicity of PPA to cancer cells was investigated through exogenous expression. A PPA gene was transduced into normal and cancer cell lines through plasmid vectors, and the effect of PPA expression was examined. Results showed that PPA translocated into the nucleus, colocalized with DNA and induced cell death. A mannose-binding motif and a V¹⁰³-W¹³⁰ region directed the nuclear translocation of PPA. Coprecipitation, mass spectrometry and western blotting analysis further indentified that PPA was associated with the methylosome, which contains methylosome protein 50 and protein arginine methyltransferase 5 (PRMT5). Knockdown of PRMT5 significantly inhibited the PPA-induced cell death, suggesting that PPA used the methylosome as a target. Furthermore, Ad.surp-PPA, an adenovirus vector in which the PPA gene was controlled by a survivin promoter (surp), selectively inhibited the proliferation of cancer cell lines. Taken together, the expression of PPA gene elicited significant cytotoxicity to cancer cells through targeting the methylosome and might be developed into a novel agent in cancer gene therapy.

Association of p53 Arg72Pro and MDM2 SNP309 polymorphisms with glioma

Epidemiological studies of the association of variants p53 Arg72Pro and MDM2 single-nucleotide polymorphism 309 (SNP309) with glioma risk have produced inconsistent results. The aim of the current study was to evaluate the association of these 2 variants with glioma susceptibility using a meta-analysis approach. For p53 Arg72Pro, 10 case-control studies including 2587 glioma patients and 4061 unrelated controls were identified. The pooled odds ratios (ORs) for Arg/Pro heterozygotes and Pro/Pro homozygotes were 1.08 [95% confidence interval (95%CI) = 0.85-1.37] and 1.08 (95%CI = 0.85-1.36), respectively, when compared to Arg/Arg carriers. Under the dominant effect model, Pro allele carriers also showed no significantly elevated glioma risk (pooled OR = 1.11, 95%CI = 0.90-1.38), and similar results were found under the recessive-effect model (pooled OR = 1.17, 95%CI = 0.85-1.61). For variant MDM2 SNP309, 3 case-control studies including 606 cases and 309 controls were identified. A marginal association with glioma risk was found for heterozygous G/T carriers (pooled OR = 1.95, 95%CI = 1.00- 3.81), whereas homozygous G/G carriers showed an increased but not significantly elevated risk of glioma (pooled OR = 2.14, 95%CI = 0.71-6.45) compared with that of T/T homozygotes. We also found no significant association between the MDM2 SNP309 polymorphism and glioma risk (pooled OR = 1.86, 95%CI = 0.94-3.67 and pooled OR = 1.25, 95%CI = 0.62-2.56, respectively) under the dominant and recessive models. Taken together, the current data suggested that the 2 polymorphisms may not contribute to glioma susceptibility.

Effects of activation on functional aster formation, microtubule assembly, and blastocyst development of goat oocytes injected with round spermatids

A systematic study was conducted on round spermatids (ROS) injection (ROSI) using the goat model. After ROSI, the oocytes were treated or not with ionomycin (ROSI+I and ROSI-I, respectively) and compared with intracytoplasmic sperm injection (ICSI). After ROSI-I, most oocytes were arrested with premature chromatin condensation and few oocytes formed pronuclei. In contrast, most oocytes formed pronuclei after ROSI+I. Some ROS were observed to form asters that organized a dense microtubule network after ROSI+I, but after ROSI-I, no ROS asters were observed. Whereas most of the oocytes showed Ca(2+) rises and a significant decline in maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) activities after ROSI+I, no such changes were observed after ROSI-I. Due to the lack of Ca(2+) oscillations after ROSI-I, oocytes were injected with more ROS. Interestingly, different from the results observed in a single ROS injection, injection with four ROS effectively activated oocytes by inducing typical Ca(2+) oscillations. Whereas ROSI+I oocytes and ICSI oocytes both showed extensive microtubule networks, no such a network was observed in parthenogenetic oocytes. Together, the results suggest that goat ROS is not able to trigger intracellular Ca(2+) rises and thus to inhibit MPF and MAPK activities, but artificial activation improved fertilization and development of ROSI goat oocytes. Goat ROS can organize functional microtubular asters in activated oocytes. A ROS-derived factor(s) may be essential for organization of a functional microtubule network to unite pronuclei. Goat centrosome is of paternal origin because both ROS and sperm asters organized an extensive microtubule network after intra-oocyte injection.

Response characteristics of Scirpus trioueter and its rhizosphere to pyrene contaminated soils at different growth stages

Scirpus triqueter (Triangular club-rush), a typical wetland species, is used to study the response characteristics to pyrene. A pot experiment was conducted to investigate the growth parameters (height, diameter, shoot number, total volume, underground biomass, above-ground biomass and total biomass), and enzymes (catalase and superoxide dismutase) of S. triqueter. The characteristics of soil enzymes (catalase and polyphenol oxidase) and microorganisms (bacteria and fungi) were also assessed after pyrene treatment. Elevated pyrene concentration (80 mgkg(-1)) in the soil reduced the shoot number and biomass significantly, especially at the early growth stage. In root tissue, the enzyme catalase was activated at 80 mgkg(-1) of pyrene. Compared to roots, shoots had higher enzyme activities. Catalase activities in the rhizosphere increased throughout the growth period of S. triqueter. Polyphenol oxidase activities in the rhizosphere were higher than those in the bulk soil and unplanted soil. The populations of bacteria (total bacteria, pyrene-tolerant bacteria, and actinomyces) and fungi decreased under the stress of high pyrene concentration, while that of pyrene-tolerant bacteria increased with the increasing pyrene concentration. The presence of pyrene did not benefit the growth of S. triqueter. S. triqueter and soil enzymes varied within the growth stages. The presence of S. triqueter could improve the activity of soil enzymes and facilitate the propagation of microorganisms which could help eliminate pyrene contamination.

Dentin regeneration using deciduous pulp stem/progenitor cells

Reparative dentin formation is essential for maintaining the integrity of dentin structure during disease or trauma. In this study, we investigated stem/progenitor cell-based tissue engineering for dentin regeneration in a large animal model. Porcine deciduous pulp stem/progenitor cells (PDPSCs) were mixed with a beta-tricalcium phosphate (β-TCP) scaffold for dentin regeneration. Different concentrations of PDPSCs were tested to determine the optimal density for dentin regeneration. Aliquots of 5×10(5) PDPSCs in 1 mL resulted in the highest number of cells attached to the scaffold and the greatest alkaline phosphatase activity. We labeled PDPSCs with green fluorescent protein (GFP) and used the optimal cell numbers mixed with β-TCP to repair pulp chamber roof defects in the premolars of swine. Four weeks after transplantation, GFP-positive PDPSCs were observed in PDPSC-embedded scaffold constructs. At 16 weeks after transplantation, the PDPSCs mixed with β-TCP significantly regenerated the dentin-like structures and nearly completely restored the pulp chamber roof defects. This study demonstrated that the PDPSC/scaffold construct was useful in direct pulp-capping and provides pre-clinical evidence for stem/progenitor cell-based dentin regeneration.

Cyclin B1 turnover and the mechanism causing insensitivity of fully grown mouse oocytes to cycloheximide inhibition of meiotic resumption

Cyclin B1 turnover and the insensitivity of fully-grown mouse oocytes to cycloheximide (CHX) inhibition of germinal vesicle breakdown (GVBD) were examined by assaying GVBD and cyclin B1 levels after treatment of oocytes with various combinations of eCG and CHX. Whereas over 95% of oocytes underwent GVBD after culture for 24 h with CHX alone, only 10% did so after culture with CHX + eCG (P < 0.05). In addition, preculture with eCG alone had no effect, but preculture with eCG + CHX prevented GVBD during a second culture with CHX alone. Therefore, we inferred that eCG delayed GVBD long enough for CHX inhibition of protein synthesis to allow cyclin B1 to decrease below a threshold where GVBD became dependent upon its de novo synthesis. However, western blot revealed no cyclin B1 synthesis, but cyclin B1 degradation, as long as GVs were maintained intact with eCG. Regarding the function of CHX in preculture without protein synthesis to block subsequent GVBD, whereas eCG delayed GVBD for only 3 h, CHX had an ongoing effect that further postponed GVBD, thus allowing cyclin B1 to decrease below the threshold. When oocytes precultured with eCG + CHX were further cultured without eCG and CHX, cyclin B1 first decreased but then, because of the ongoing effects of CHX, increased to a level sufficient to induce GVBD. The content of P34Cdc2 was not altered under any of the culture conditions (P > 0.05). We concluded that insensitivity of mouse germinal vesicle (GV) oocytes to CHX was due to the presence of sufficient cyclin B1, and that cyclin B1 level in such oocytes was maintained by an equilibrium between synthesis and degradation.

Alterations in the mortality and growth cycle of cervical cancer cells treated with electroporation at different electric strengths

OBJECTIVE

To explore the biological effects of electric fields of various strengths on Hela cells.

METHODS

Electroporation experiments were performed using Hela cells. Changes in cell mortality, cell vitality, cell cycle, and apoptosis status were examined. In addition, temperature changes in the surrounding tissue were measured.

RESULTS

Cell proliferation was markedly inhibited after treatment with field strengths of 2-2.5 kV/cm. The expression of caspase-3 increased significantly in cells treated with field strengths of 1.5-2.5 kV/cm. Field strengths of 1.75-2.5 kV/cm produced complete cancer cell ablation. G2 phase frequency increased significantly after treatment with field strengths of 2-2.5 kV/cm. During this process, the maximum temperature increase in the pulsed electric field was 4.9 -/+ 1.17 degrees C under free air convection.

CONCLUSIONS

IRE can be used alone for the treatment of cancer, and its thermal effect is negligible. Cell death was caused by the effects of IRE and apoptosis. The tumor cells must be destroyed completely, or the altered cell cycle may lead to tumor recurrence and accelerated growth.

Synthesis and anti-HIV activity of novel 2,4-disubstituted-7-methyl-1,1,3-trioxo-2H,4H-pyrazolo[4,5-e][1,2,4]thiadiazine derivatives

A series of novel 2,4-disubstituted-7-methyl-1,1,3-trioxo-2H,4H-pyrazolo[4,5-e][1,2,4]thiadiazines (PTDs) was prepared starting from a ring of pyrazolo[4,5-e][1,2,4]thiadiazine nuclei with two different alkyl halides obtained by a facile one-pot reaction. The structures of all synthesized compounds were confirmed by ¹H- and ¹³C-NMR, infrared spectra (IR), and mass spectra (MS) spectroscopic analysis. Anti-HIV activity was evaluated and none of the compounds were found to inhibit HIV replication in human T-lymphocyte (MT-4) cell culture.

Loss of macrophage migration inhibitory factor impairs the growth properties of human HeLa cervical cancer cells

OBJECTIVES

  This study aims to determine the role of macrophage migration inhibitory factor (MIF), a proinflammatory cytokine associated with cell proliferation and tumour growth in vivo.

MATERIALS AND METHODS

  Our team used RNA interference technology to knock down MIF expression in human HeLa cervical cancer cells and to establish a stable cell line lacking MIF function.

RESULTS

  Our results showed that long-term loss of MIF had little effect on cell morphology, but significantly inhibited their population growth and proliferation. The HeLa MIF-knockdown cells retained normal apoptotic signalling pathways in response to TNF-alpha treatment; however, they exhibited unique DNA profiles following doxorubicin treatment, suggesting that MIF may regulate a cell cycle checkpoint upon DNA damage. Our data also showed that knockdown of MIF expression in HeLa cells led to increased cell adhesion and therefore impaired their migratory capacity. More importantly, cells lacking MIF failed to either proliferate in soft agar or form tumours in vivo, when administered to nude mice.

CONCLUSION

  MIF plays a pivotal role in proliferation and tumourigenesis of human HeLa cervical carcinoma cells, and may represent a promising therapeutic target for cancer intervention.

(137)Cs, (239+240)Pu concentrations and the (240)Pu/(239)Pu atom ratio in a sediment core from the sub-aqueous delta of Yangtze River estuary

A sediment core collected from the sub-aqueous delta of the Yangtze River estuary was subjected to analyses of (137)Cs and plutonium (Pu) isotopes. The (137)Cs was measured using γ-spectrometry at the laboratories at the Nanjing University and Pu isotopes were determined with Accelerator Mass Spectrometry (AMS), measurements made at the Australian National University. The results show considerable structure in the depth concentration profiles of the (137)Cs and (239+240)Pu. The shape of the vertical (137)Cs distribution in the sediment core was similar to that of the Pu. The maximum (137)Cs and (239+240)Pu concentrations were 16.21 ± 0.95 mBq/g and 0.716 ± 0.030 mBq/g, respectively, and appear at same depth. The average (240)Pu/(239)Pu atom ratio was 0.238 ± 0.007 in the sediment core, slightly higher than the average global fallout value. The changes in the (240)Pu/(239)Pu atom ratios in the sediment core indicate the presence of at least two different Pu sources, i.e., global fallout and another source, most likely close-in fallout from the Pacific Proving Grounds (PPG) in the Marshall Islands, and suggest the possibility that Pu isotopes are useful as a geochronological tool for coastal sediment studies. The (137)Cs and (239+240)Pu inventories were estimated to be 7100 ± 1200 Bq/m(2) and 407 ± 27 Bq/m(2), respectively. Approximately 40% of the (239+240)Pu inventory originated from the PPG close-in fallout and about 50% has derived from land-origin global fallout transported to the estuary by the river. This study confirms that AMS is a useful tool to measure (240)Pu/(239)Pu atom ratio and can provide valuable information on sedimentary processes in the coastal environment.

Transfection of hairpin small interfering RNA expression vector targeting rat nuclear factor (NF) (κB) inhibits rat cell proliferation induced by NF-κB signal pathway activation

OBJECTIVE

The aim of this work was to construct one small interfering RNA (siRNA) eukaryotic expression vector targeting rat nuclear factor (NF)κB p65 and identify its inhibition effect on cell proliferation according to its down-regulation of NF-κB pathway.

METHODS

The p65siRNA expression vector "pGenesil-1.2-p65siRNA" and negative control plasmid "HK" were transfected into the cultured rat cells. After transfection, cells were divided into 4 treatment groups: 1) control cells cultured in complete. Dulbecco modified Eagle medium; 2) lipopolysaccharide (LPS) (1 μg/mL); (3) LPS (1 μg/mL) + HK-transfected; 4) LPS (1 μg/mL) + p65siRNA (pGenesil-1.2-p65siRNA). Thereafter, the protein levels of NF-κB p65 in the cells were detected by Western blotting at 72 hours after LPS stimulation. Furthermore, to observe cell proliferation, the proliferative rate of the cell growth was evaluated by the methylthiazolyl tetrazolium assay (at 24, 48, and 72 hours). The cell cycle distribution at 72 hours was detected by flow cytometry.

RESULTS

p65siRNA effectively down-regulated the protein level of p65 (P < .05). Meanwhile, the proliferation of cells transfected with p65siRNA expression vector was significantly inhibited (P < .05), the ratio of cells at G(0)/G(1) stage markedly increased, and the proportion of cells at S stage was significantly decreased among transfected compared with control cells (P < .05).

CONCLUSIONS

p65siRNA effectively suppressed NF-κB, expression, inhibiting rat cell proliferation induced by NF-κB signal pathway activation.

Genetic algorithm-based efficient feature selection for classification of pre-miRNAs

In order to classify the real/pseudo human precursor microRNA (pre-miRNAs) hairpins with ab initio methods, numerous features are extracted from the primary sequence and second structure of pre-miRNAs. However, they include some redundant and useless features. It is essential to select the most representative feature subset; this contributes to improving the classification accuracy. We propose a novel feature selection method based on a genetic algorithm, according to the characteristics of human pre-miRNAs. The information gain of a feature, the feature conservation relative to stem parts of pre-miRNA, and the redundancy among features are all considered. Feature conservation was introduced for the first time. Experimental results were validated by cross-validation using datasets composed of human real/pseudo pre-miRNAs. Compared with microPred, our classifier miPredGA, achieved more reliable sensitivity and specificity. The accuracy was improved nearly 12%. The feature selection algorithm is useful for constructing more efficient classifiers for identification of real human pre-miRNAs from pseudo hairpins.

TMPDP, a tetramethylpyrazine derivative, protects vascular endothelial cells from oxidation damage by hydrogen peroxide

A novel ligustrazine derivative, tetramethylpyrazine diphenylmethyl piperazidine (TMPDP), prepared by hybridization and bioisosteric replacement of the molecular structure of TMP, was studied for its protective effects on oxidative damage of human umbilical vein endothelial cells (HUVECs) in response to hydrogen peroxide (H2O2). The antioxidative effect of TMPDP was assessed by the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) test. Cell viability was measured using a 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The activity of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione peroxidase (GSH) and the content of malondialdehyde (MDA) in cells were determined by commercial kits. The intracellular formation of reactive oxygen species (ROS) and the concentration of free intracellular calcium ([Ca2+]i) were determined using DCFH-DA assay and with fura-2/AM fluorimetry, respectively. Results showed that TMPDP had a moderate antioxidative effect against DPPH. Cell viability was decreased markedly by exposure to H2O2. Introduction of TMPDP, however, significantly increased cell viability, markedly reduced LDH release from cells and decreased lipid peroxidation in response to H2O2 treatment. These effects of TMPDP were accompanied by increased activity of the endogenous antioxidant enzymes, SOD and GSH, reduced production of ROS and reduced intracellular concentration of Ca2+. These results suggest that TMPDP protects HUVECs against oxidative damage by scavenging ROS and regulates intracellular calcium concentration. This might have important implications for the development of new agents for the effective treatment of vascular disease.

New technique for mouse oocyte injection via a modified holding pipette

To improve mouse oocyte survival from intracytoplasmic sperm injection, the sharp tip of the injection pipette has been modified to have a flat end. Here, for the same goal but for a more convenient manipulation, a sharp injection pipette was kept whereas the holding pipette was modified to have a trumpet-shaped opening, which allows deeper injection into the oocyte as it is held. Mouse oocyte injection with mouse and human spermatozoa was performed at 37°C. For the injection of mouse oocyte with mouse sperm head, a significantly higher survival rate (83%) was achieved by utilizing the modified holding pipette than the conventional one (21%; P<0.001) and the fertilization rates were normal and comparable for both methods (82% versus 81%). A superior survival rate (82%) and acceptable normal fertilization rate (71%) were also achieved by utilizing the modified holding pipette for interspecies ICSI (injecting mouse oocyte with human spermatozoon). Taken together, by utilizing a holding pipette with a trumpet-shaped opening, acceptable rates of mouse oocyte survival and fertilization can be achieved using a sharp injection pipette under conditions usual for human oocyte injection.

[Progress in the study of HIV-1 Vif and related inhibitors]

Human immunodeficiency virus type 1 (HIV-1) viral infectivity factor (Vif), one of the accessory proteins, which is a small basic phosphoprotein, is essential for viral replication and pathogenesis. The best well-characterized function of Vif is its ability to neutralize the host cell antiviral factor, apolipoprotein B mRNA editing enzyme catalytic polypeptide like 3G (APOBEC3G), which makes the viral particles more infective. In addition, Vif can regulate the reverse transcription and the advanced stage of replication of the virus particle, as well as induce the termination of cell cycle at G2 stage and so on. The designed drug aimed directly at Vif can efficiently block the maturation and infectivity of HIV-1. In this review, the structure, function and especially the related inhibitors of Vif are reviewed.