Effects of lipids and surfactants on the fermentation production of echinocandin B by Aspergillus nidulans

AIMS

Echinocandin B (ECB) is a kind of lipopeptide antifungal antibiotic, as well as the key precursor of antifungal drug Anidulafungin. Its efficient bioproduction plays an important role in promoting the industrial production of Anidulafungin.

METHODS AND RESULTS

In this study, methyl oleate and Tween 80 were firstly used to enhance the ECB fermentation by Aspergillus nidulans, the results showed that the ECB titre was significantly enhanced with the addition of methyl oleate and Tween 80. Among the lipids, methyl oleate was found to play a pivotal role in increasing the ECB titre to 2123 mg l^-1 , which was more than five times higher than that of the control. The addition of Tween 80 in the medium resulted in ECB titre increased to 2584 mg l^-1 . The scanning electron microscope (SEM) and N-phenyl-1-naphthylamine (NPN) assay indicated that Tween 80 could influence the cell membrane permeability of A. nidulans, and enhance the intracellular and extracellular substance exchange, therefore lead to the increasing of ECB titre.

CONCLUSIONS

Methyl oleate and Tween 80 are optimal carbon sources and surfactants for efficient ECB biosynthesis respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

Surfactant was used in ECB fermentation for the first time, which provided feasible ideas for optimizing the fermentation process of other fungi.

Design, synthesis, and cytotoxic activity of novel 2H-imidazo[1,2-c]pyrazolo[3,4-e]pyrimidine derivatives

In this study, a series of novel 2H-imidazo [1, 2-c] pyrazolo [3, 4-e] pyrimidine derivatives were designed, synthesized, and evaluated for their cytotoxic activities. The in vitro cell growth inhibition assay of the target compounds indicated their selectivity in inhibiting the proliferation of blood tumor cells (K562, U937) and solid tumor cells (HCT116, HT-29). Compound 9b exhibited the highest antiproliferative activities against K562 (IC₅₀ = 5.597 µM) and U937 (IC₅₀ = 3.512 µM). Based on the flow cytometry assays, compound 9b caused obvious induction of cell apoptosis and cell arrest at the S phase. Furthermore, western blot analysis revealed that compound 9b upregulated the expression of Bax, downregulated the levels of Bcl-2, and further activated caspase-3 in K562 cells. Therefore, compound 9b may be a potential anticancer agent that deserves further investigation.

Design, synthesis, biological activity evaluation of 3-(4-phenyl-1H-imidazol-2-yl)-1H-pyrazole derivatives as potent JAK 2/3 and aurora A/B kinases multi-targeted inhibitors

In this study, a series of 3-(4-phenyl-1H-imidazol-2-yl)-1H-pyrazole derivatives were designed, synthesized, and evaluated for their biological activities. Upon performing kinase assays, most of the compounds exhibited potent inhibition against JAK2/3 and Aurora A/B with the IC₅₀ values ranging from 0.008 to 2.52 μM. Among these derivatives, compound 10e expressed the most moderate inhibiting activities against all the four kinases with the IC₅₀ values of 0.166 μM (JAK2), 0.057 μM (JAK3), 0.939 μM (Aurora A), and 0.583 μM (Aurora B), respectively. Moreover, most of the derived compounds exhibited potent cytotoxicity against human chronic myeloid leukemia cells K562 and human colon cancer cells HCT116, while compound 10e expressed antiproliferative activities against K562 (IC₅₀₌6.726  μM). According to western blot analysis, compound 10e down-regulated the phosphorylation of STAT3, STAT5, Aurora A, and Aurora B in a dose-dependent manner in K562 and HCT116 cells. Cell cycle analysis revealed that compound 10e inhibited the proliferation of cells by inducing cell cycle arrest in the G2 phase. The molecular modeling suggested that compound 10e could maintain a binding mode similar to the binding mode of AT9832, a common JAK 2/3 and Aurora A/B kinases multi-target kinase inhibitor. Therefore, compound 10e might be a potential agent for cancer therapy deserving further research.

Design and synthesis of a novel photoaffinity probe for labelling EGF receptor tyrosine kinases

The epidermal growth factor receptor (EGFR) and HER2 are two important tyrosine kinases that play crucial roles in signal transduction pathways that regulate numerous cellular functions including proliferation, differentiation, migration, and angiogenesis. In the past 20 years, many proteomic methods have emerged as powerful methods to evaluate proteins in biological processes and human disease states. Among them, activity-based protein profiling (ABPP) is one useful approach for the functional analysis of proteins. In this study, a novel photoaffinity probe 11 was designed and synthesised to assess the target profiling of the reactive group in the photoaffinity probe 11. Biological evaluation was performed, and the results showed that the novel photoaffinity probe binds to EGFR and HER2 proteins and it hits targets by the reactive group.

Network-scale effect on synchronizability of fully coupled network with connection delay

Network-scale effect on synchronizability of fully coupled network with connection delay is investigated in this paper. The master stability function, which governs the stability of synchronization manifold, is first obtained by separating the synchronization manifold direction from other transverse directions. Then, by introducing a new time variable in the master stability function, it is shown the effect of connection delay can be weakened with the increase of network scale, and thus, in contrast to the situation without connection delay, large network scale is more positive to the synchronizability of fully coupled network with connection delay. Those findings are confirmed by the studies on two specific networks with nodes of typical nonlinear dynamical systems.

Water filling and electric field-induced enhancement in the mechanical property of carbon nanotubes

The effects of water filling and electric field on the mechanical property of carbon nanotubes (CNTs) are investigated with molecular dynamics simulations. The simulation results indicate that the water filling and electric field could enhance the elastic modulus but reduce the Poisson's ratio of the CNTs. As for the buckling behaviors, a significant enhancement could be observed in the yield stress and average post-buckling stress of the CNTs. In particular, the enhancement in the yield stress induced by the water filling and electric field could be even higher than that resulted from the solid filling. Moreover, a transition mechanism from the rod instability to shell buckling is shown to explain the nonmonotonic variation of yield stress, and the critical diameter can be tuned through filling the water molecules and applying the electric field. The present findings provide a valuable route for the optimized design and application of the nanoscale functional devices based on the water-filled CNTs.

Down-regulation of microRNA-126 and microRNA-133b acts as novel predictor biomarkers in progression and metastasis of non small cell lung cancer

OBJECTIVE

MiRNAs play crucial roles in progression of cancer. However, the underlying mechanisms of miRNAs in non small cell lung cancer are still poorly understood. The aim of this study was to investigate the expression level of microRNA-126 (miR-126) and microRNA-133b (miR-133b) and also their association with clinicopathological features in patients with non small cell lung cancer (NSCLC).

METHODS

Total RNA was purified from NSCLC tissues and adjacent non-tumor tissues and then quantitative real-time PCR (qRT-PCR) was used to evaluate the expression rate of microRNAs. Furthermore, the association of miR-126 and miR-133b level with clinicopathological features and prognosis were evaluated.

RESULTS

Our findings showed that expression of miR-126 was decreased in NSCLC tissues compared with adjacent non-tumor tissues. On the other hand, a lower expression of miR-133b was seen in NSCLC tissues when compared with adjacent non-tumor tissues. In term of miR-126, our results showed that miR-126 was associated with tumor stage and lymph nodes metastasis (P<0.05). In term of miR-133b, our finding indicated that decreased expression of miR-133b was correlated with advanced tumor stage and lymph nodes metastasis (P<0.05). Kaplan-Meier analysis and log-rank test indicated that patients with low expression of miR-126 and miR-133b had a shorter overall survival (log-rank test; P<0.05). Multivariate Cox proportional hazards model revealed that low expression of miR-126 and miR-133b, advanced tumor stage and lymph nodes metastasis were independent prognostic factors for overall survival of NSCLC patients.

CONCLUSIONS

These findings suggested that miR-126 and miR-133b might play a key role in the progression and metastasis of NSCLC and would be applied as a novel therapeutic agent.

Size-dependent elastic moduli and vibrational properties of fivefold twinned copper nanowires

Based on atomistic simulations, the elastic moduli and vibration behaviors of fivefold twinned copper nanowires are investigated in this paper. Simulation results show that the elastic (i.e., Young's and shear) moduli exhibit size dependence due to the surface effect. The effective Young's modulus is found to decrease slightly whereas the effective shear modulus increases slightly with the increase in the wire radius. Both moduli tend to approach certain values at a larger radius and can be suitably described by core-shell composite structure models. Furthermore, we show by comparing simulation results and continuum predictions that, provided the effective Young's and shear moduli are used, classic elastic theory can be applied to describe the small-amplitude vibration of fivefold twinned copper nanowires. Moreover, for the transverse vibration, the Timoshenko beam model is more suitable because shear deformation becomes apparent.

Expression of ERCC1 and BRCA1 predict the clinical outcome of non-small cell lung cancer in patients receiving platinum-based chemotherapy

We examined mRNA expression levels of ERCC1, BRCA1, RRM1, and human β-tubulin-III (TUBB3) in non-small-cell lung carcinoma (NSCLC) patients and investigated the association between expression of these genes and the clinical outcome of NSCLC treatment. A total of 366 patients who underwent surgery for NSCLC were included in this study. All patients received third-generation platinum-based chemotherapy as first-line treatment. The relative cDNA quantification for ERCC1, RRM1, BRCA1, and TUBB3 was determined using a fluorescence-based, real-time detection method. We found that low expression of ERCC1 and BRCA1 was associated with a good response to platinum-based chemotherapy, with an odds ratio [95% confidence interval (CI)] of 2.09 (1.33-3.27) and 2.92 (1.85-4.62), respectively. Multivariate Cox regression analysis indicated that patients with low expression of ERCC1 and BRCA1 attained a longer overall survival time than those with high expression, with a hazard ratio (95%CI) of 0.42 (0.23-0.77) and 0.39 (0.21-0.71), respectively. However, RMM1 and TUBB2 expressions were not correlated with clinical outcome of NSCLC. In conclusion, we found that low expression of ERCC1 and BRCA1 can be useful for selecting NSCLC patients who would benefit from chemotherapy and warrants further investigation in prospective studies.

Time-delay effect on the bursting of the synchronized state of coupled Hindmarsh-Rose neurons

The time-delay effect on the bursting of the synchronized state of coupled Hindmarsh-Rose neurons is investigated in this paper. The time-delay influence on the structure of the slow manifold is first studied by using the method of stability switch. And then on the basis of the geometric singular perturbation theory, case studies are given to show that the time delay can suppress the bursting oscillation or lead to more complex dynamics. In particular, the mechanism of the transition from bursting oscillation to relaxation oscillation and to chaotic bursting is stated. Numerical results are given to demonstrate the validity of the analytical results.

Stability study on the nitrile hydratase of Nocardia sp. 108: from resting cell to crude enzyme preparation

In recent years, nitrile hydratases (NHases) have drawn increasing attentions due to their critical roles in organic synthesis. In present paper, extensive investigation on the stability and activity of the NHase from Nocardia sp. 108, which is succeed in the industrial application in China, were conducted by the bioconversion of acrylonitrile to acrylamide in a batch manner. Cultivation study demonstrated that biosynthesis of NHase changed significantly with culture time, and the optimal NHase biosynthesis phase was 45 h after inoculation with NHase activity of 1209.8 U/g of biomass. Stability study indicated that crude enzyme preparation both exhibit a good stability when exposed to the pH 7.2 tris-HCl buffer at 4 degrees C for 4 h.

ESR studies on reaction of saccharide with the free radicals generated from the xanthine oxidase/hypoxanthine system containing iron

The free radicals generated from the iron containing system of xanthine oxidase and hypoxanthine (Fe-XO/HX) were directly detected by using spin trapping. It was found that not only superoxide anion (O(2)*-) and hydroxyl radical (OH*), but also alkyl or alkoxyl radicals (R*) were formed when saccharides such as glucose, fructose and sucrose were added into the Fe-XO/HX system. The generated amount of R* was dependent on the kind and concentration of saccharides added into the Fe-XO/HX system and no R* were detected in the absence of saccharides, indicating that there is an interaction between the saccharide molecules and the free radicals generated from the Fe-XO/HX system and saccharide molecules are essential for generating R* in the Fe-XO/HX system. It is expected that the toxicity of R* would be greater than of hydrophilic O(2)*- and OH* because they are liposoluble and their lives are longer and the active sites of biomolecules are closely related with lipophilic phase, thus they can damage cells more seriously than O(2)*- and OH*. The R* generated from the saccharide containing Fe-XO/HX can be effectively scavenged by selenium containing abzyme (Se-abzyme), indicating Se-abzyme is a promising antioxidant.

[An epidemiologic study of workers with low back pain]

To evaluate the impact of low back pain we conducted a cross-sectional epidemiologic study of 10087 workers in factories of textile, machinery auto-transportation, clothing and sea cultivation. The prevalence of pain was compared with ages, sexes, duration of employment, types of jobs as well as body posture. The prevalence of low back in males was 13.66%, and in females 8.75% (average 11.53%). The risk factors included lifting, bending, twisting prolonged sitting and vibration as well as moisture and coldness prolonged sitting was. The important contributing factor of low back pain in sedentary workers.

[Developmental stenosis of the cervical spinal canal hyperextension injury]

Sixteen cases of cervical spinal cord injury with developmental stenosis of cervical spinal canal were treated. The numbness and quadriplegia of the patients were caused by hyperextension X-ray of the cervical spine showed no fracture or dislocation but the sagittal diameter of the canal and that of the corresponding cervical vertebral body was less than 0.75. All of the patients were treated by operation including laminoplasty on 12 cases. The numbness and quadriplegia in most of the patients were improved obviously after operation. The mechanism of hyperextension injury on the cervical spinal cord was discussed. When spinal column was extended, annulus fibrosus of disk and ligamentum flavum would enfold into the spinal canal and only a slight force would do severe on the cord. Laminoplasty is the recommended treatment for this kind of lesions.