RESUMEN

Targeted delivery and precise release of toxins is a prospective strategy for the treatment of triple-negative breast cancer (TNBC), yet the flexibility to incorporate both properties simultaneously remains tremendously challenging in the X-drug conjugate fields. As critical components in conjugates, linkers could flourish in achieving optimal functionalities. Here, we pioneered a pH-hypersensitive tumor-targeting aptamer AS1411-triptolide conjugate (AS-TP) to achieve smart release of the toxin and targeted therapy against TNBC. The multifunctional acetal ester linker in the AS-TP site-specifically blocked triptolide toxicity, quantitatively sustained aptamer targeting, and ensured the circulating stability. Furthermore, the aptamer modification endowed triptolide with favorable water solubility and bioavailability and facilitated endocytosis of conjugated triptolide by TNBC cells in a nucleolin-dependent manner. The integrated superiorities of AS-TP promoted the preferential intra-tumor triptolide accumulation in xenografted TNBC mice and triggered the in-situ triptolide release in the weakly acidic tumor microenvironment, manifesting striking anti-TNBC efficacy and virtually eliminated toxic effects beyond clinical drugs. This study illustrated the therapeutic potential of AS-TP against TNBC and proposed a promising concept for the development of nucleic acid-based targeted anticancer drugs.

Asunto(s)

RESUMEN

Kaempferol is a natural flavonoid with reported bioactivities found in many fruits, vegetables, and medicinal herbs. However, its effects on exercise performance and muscle metabolism remain inconclusive. The present study investigated kaempferol's effects on improving exercise performance and potential mechanisms in vivo and in vitro. The grip strength, exhaustive running time, and distance of mice were increased in the high-dose kaempferol group (p < 0.01). Also, kaempferol reduced fatigue-related biochemical markers and increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) related to antioxidant capacity. Kaempferol also increased the glycogen and adenosine triphosphate (ATP) content in the liver and skeletal muscle, as well as glucose in the blood. In vitro, kaempferol promoted glucose uptake, protein synthesis, and mitochondrial function and decreased oxidative stress in both 2D and 3D C2C12 myotube cultures. Moreover, kaempferol activated the PI3K/AKT and MAPK signaling pathways in the C2C12 cells. It also upregulated the key targets of glucose uptake, mitochondrial function, and protein synthesis. These findings suggest that kaempferol improves exercise performance and alleviates physical fatigue by increasing glucose uptake, mitochondrial biogenesis, and protein synthesis and by decreasing ROS. Kaempferol's molecular mechanism may be related to the regulation of the PI3K/AKT and MAPK signaling pathways.

RESUMEN

INTRODUCTION: Phosphatidylinositol 3-kinases (PI3Ks) overexpression can elicit cellular homeostatic dysregulation, which further contributes to tumorigenesis, with PI3Kα emerging as the most prevalent mutant isoform kinase among PI3Ks. Therefore, selective inhibitors targeting PI3Kα have attracted considerable interest in recent years. Molecular hybridization, with the advantage of simplified pharmacokinetics and drug-drug interactions, emerged as one of the important avenues for discovering potential drugs. OBJECTIVES: This study aimed to construct PI3Kα inhibitors by hybridization and investigate their antitumor activity and mechanism. METHODS: 26 quinazoline-2-indolinone derivatives were obtained by molecular hybridization, and their structure-activity relationship was analyzed by MTT, in vitro kinase activity and molecular docking. The biological evaluation of compound 8 was performed by transwell, flow cytometry, laser scanning confocal microscopy, Western blot, CTESA and immunohistochemistry. RESULTS: Here, we employed molecular hybridization methods to construct a series of quinazoline-2-indolinone derivatives as PI3Kα selective inhibitors. Encouragingly, representative compound 8 exhibited a PI3Kα enzymatic IC50 value of 9.11 nM and 10.41/16.99/37.53-fold relative to the biochemical selectivity for PI3Kß/γ/δ, respectively. Moreover, compound 8 effectively suppressed the viability of B16, HCT116, MCF-7, H22, PC-3, and A549 cells (IC50 values: 0.2 µM âˆ¼ 0.98 µM), and dramatically inhibited the proliferation and migration of NSCLC cells, as well as induced mitochondrial apoptosis through the PI3K/Akt/mTOR pathway. Importantly, compound 8 demonstrated potent in vivo anti-tumor activity in non-small cell lung cancer mouse models without visible toxicity. CONCLUSIONS: This study presented a new avenue for the development of PI3Kα inhibitors and provided a solid foundation for novel QHIDs as potential future therapies for the treatment of NSCLC.

RESUMEN

The identification of active components is critical for the development of sports supplements. However, high-throughput screening of active components remains a challenge. This study sought to construct prediction models to screen active components from herbal medicines via machine learning and validate the screening by using cell-based assays. The six constructed models had an accuracy of >0.88. Twelve randomly selected active components from the screening were tested for their active potency on C2C12 cells, and 11 components induced a significant increase in myotube diameters and protein synthesis. The effect and mechanism of luteolin among the 11 active components as potential sports supplements were then investigated by using immunofluorescence staining and high-content imaging analysis. It showed that luteolin increased the skeletal muscle performance via the activation of PGC-1α and MAPK signaling pathways. Thus, high-throughput prediction models can be effectively used to screen active components as sports supplements.

RESUMEN

(1) Background: Polygonatum cyrtonema is a medicinal plant, and its polysaccharides are used for immunomodulation and the treatment of hyperglycemia. Investigation of the tissue distribution and pharmacokinetics of P. cyrtonema polysaccharide can further elucidate its pharmacological mechanisms. (2) Methods: A fluorescence-labeling approach using rhodamine B (RhB) as a fluorescent molecular probe was used for the quantitative assessment of the polysaccharide from dried P. cyrtonema (DPC1) samples, and the pharmacokinetics and tissue distribution of DPC1 were evaluated in mice after intraperitoneal or oral administration. (3) Results: DPC1 was successfully labeled with RhB, showing degrees of fluorescence labeling at 0.453% and 0.568% as determined by the ultraviolet and enzyme marker methods, respectively. DPC1-RhB was rapidly absorbed into the bloodstream after oral and intraperitoneal administration. Pharmacokinetic characteristics showed that oral administration and intraperitoneal administration were consistent with the features of a two-compartment model. (4) Conclusion: After administration, DPC1-RhB was primarily distributed in the tissues of the heart, spleen, and lung, indicating that the drug has a targeted effect on these tissues. Overall, the findings provide a comprehensive reference for the in vivo distribution of DPC1, together with a foundation for further elucidation of its pharmacological mechanisms and the development and application of DPC1 formulations.

RESUMEN

Triggering ferroptosis is a potential therapeutic pathway and strategy for the prospective treatment of lethal hepatocellular carcinoma (HCC). The asialo-glycoprotein receptor (ASGPR) is an over-expressed receptor on the membranes of hepatocellular carcinoma cells (HCCs) and binds specifically to galactose (Gal) ligand. Celastrol (CE) is a potent anticancer natural product, but its poor water solubility and severe toxicity restrict its clinical application. In this study, a carrier-free self-assembled nanoparticles, CE-Gal-NPs, were designed and prepared by nanoprecipitation method, which could recognize ASGPR receptor by active targeting (Gal ligand) and passive targeting (EPR effect), access to the cell through the clathrin pathway and finally internalize to lysosomes. CE-Gal-NPs triggered reactive oxygen species (ROS)-mediated ferroptosis pathway and exerted anti-HCC effects in vitro and in vivo by down-regulating GPX4 and up-regulating COX-2 expression, depleting glutathione (GSH) levels, and increasing lipid peroxidation levels in cells and tumor tissues. In the H22 xenograft mouse model, the CE-Gal-NPs group exhibited dramatically superior tumor inhibition than the CE group, while Gal conjugating diminished the systemic toxicity of CE. Consequently, this study presented a promising strategy for CE potentiation and toxicity reduction, as well as a potential guideline for the development of clinically targeted therapeutic agents for HCC.

Asunto(s)

RESUMEN

Tetrandrine (TET) possesses multiple pharmacological activities and could suppress tumor proliferation via PI3K pathway inhibition. However, inferior antitumor activity and potential toxicity limit its clinical application. In the present study, a series of 14-sulfonamide and sulfonate TET derivatives were designed, synthesized, and evaluated for biological activities. Through structural-activity relationship studies, compound 3c with α, ß-unsaturated carbonyl group exhibited the most potent activity against all tested tumor cell lines (including Hela, HCT116, HepG2, MCF-7, and SHSY5Y), as well as negligible toxicity against normal cell lines LO2 and HEK293. Additionally, compound 3c effectively inhibited HCT116 and CT26 cell proliferation in vitro with increased cell proportion in the G2/M phase, activated the mitochondrial apoptosis pathway, and induced colon cancer cell apoptosis by suppressing the PI3K/AKT/mTOR pathway. The further molecular docking results confirmed that compound 3c is potentially bound to multiple residues in PI3K with a stronger binding affinity than TET. Ultimately, compound 3c dramatically suppressed tumor growth in the CT26 xenograft tumor model, without noticeable visceral toxicity detected in the high-dose group. In summary, compound 3c might present new insights for designing new PI3K inhibitors and be a potential candidate for colon cancer treatment.

Asunto(s)

RESUMEN

Triple-negative breast cancer (TNBC), as the most aggressive subtype of breast cancer, presents a scarcity of miraculous drugs in suppressing its proliferation and metastasis. Bruceine A (BA) is a functional group-rich quassin compound with extensive and distinctive pharmacological activities. Within the present study, we investigated the capabilities of BA in suppressing TNBC proliferation and metastasis as well as its potential mechanisms. The results displayed that BA dramatically repressed the proliferation of MDA-MB-231 and 4T1 cells with corresponding IC50 values of 78.4 nM and 524.6 nM, respectively. Concurrently, BA arrested cells in G1 phase by downregulating cycle-related proteins Cyclin D1 and CDK4. Furthermore, BA distinctly induced mitochondrial dysfunction as manifested by diminished mitochondrial membrane potential, elevated reactive oxygen species generation, minimized ATP production, and Caspase-dependent activation of the mitochondrial apoptosis pathway. Additionally, BA restrained the invasion and metastasis of TNBC cells by repressing MMP9 and MMP2 expression. Intriguingly, after pretreatment with MEK activator C16-PAF, the inhibitory effect of BA on MEK/ERK pathway was notably diminished, while the proliferation suppression and metastasis repression exerted by BA were all strikingly curtailed. Molecular docking illustrated that BA potently combined with residues on the MEK1 protein with the presence of diverse intermolecular interactions. Ultimately, BA effectively suppressed tumor growth in the 4T1 xenograft tumor model with no detectable visceral toxicity in the high-dose group and, astonishingly, repressed tumor metastasis in the 4T1-luc lung metastasis model. Collectively, our study demonstrates that BA is a promising chemotherapeutic agent for treating TNBC and suppressing lung metastasis.

Asunto(s)

RESUMEN

Bruceine A (BA), a quassic ester from bruceine javanica, regulates diverse intracellular signal transduction pathways and manifests a variety of biological activities, however, its pharmacological mechanism in treating colon cancer (CC) is unclear. In this study, we investigated the anticancer effects of BA on CC cells and the underlying mechanisms. The network pharmacology research indicated that Akt1 and Jun and PI3K/Akt pathways are the predominant targets and critical signaling pathways, respectively, for BA treatment of CC. Meanwhile, molecular docking results implied that BA could conjugate to pivotal proteins in the PI3K/Akt pathway. BA remarkably suppressed the proliferation of CC cells HCT116 and CT26 with 48-h IC50 of 26.12 and 229.26 nM, respectively, and the expression of p-PI3K/p-Akt was restrained by BA at the molecular level as verified by Western blot assay. Further mechanistic studies revealed BA impacted cell cycle-related proteins by regulating the expression of P27 (a protein bridging the PI3K/Akt signaling pathway with cycle-related proteins), arresting the cell cycle in the G2 phase, inhibiting the proliferation of HCT116 and CT26, and facilitated the apoptosis in CC cells by activating the mitochondria-associated apoptosis protein Bax and accumulating reactive oxygen species, in addition to BA apparently inhibited the migration of CC cells. Taken together, our results demonstrated that BA might be a promising chemotherapy drug in the treatment of CC.

RESUMEN

Strong-flavor Baijiu (SFB) is produced in complex fermentation in pits under ground. Clostridium producing hexanoic acid plays a key role in the flavor formation of SFB. The screening and culture for Clostridium are very difficult because of its strict anaerobic characteristics. In this study, electric field assisted screening (EFAS) was used to screen Clostridium from pit mud, and electric culture (EC) was used to cultivate Clostridium under non-anaerobic conditions. A strain with a high yield of hexanoic acid was screened and named as Clostridium sp. EFAS6. Under non-anaerobic conditions, it grew rapidly only near the cathode end in the EFAS device because of the low oxidation-reduction potential of that electrode. In the experiment of high-density culture in the EC device, the cell concentration reached 106-107. After energy consumption was calculated, the optimal loading voltage was found to be 10 V. In the application, the broth of Clostridium sp. EFAS6 increased the content of ethyl hexanoic in SFB. Under non-anaerobic conditions, the anaerobe was screened by EFAS and cultivated in high density by EC. The EFAS and EC could also be used for the screening and culture of other anaerobes under non-anaerobic conditions.

Asunto(s)

RESUMEN

Colorectal cancer (CRC), among the most aggressive and prevailing neoplasms, is primarily treated with chemotherapy. Voacamine (VOA), a novel bisindole natural product, possesses a variety of conspicuous pharmacological activities. Within the current research, we evaluated in vitro and in vivo the anticancer efficacy of VOA against CRC and its potential mechanisms. Our results illustrated that VOA concentrationdependently suppressed the proliferation and migration of CT26 and HCT116 cells as correspondingly indicated by IC50 values of 1.38 ± 0.09 µM and 4.10 ± 0.14 µM. Furthermore, treatment of VOA also suppressed tumor cell colony formation, escalated the late-stage apoptosis rate of tumor cells, and evoked cell cycle of CT26 and HCT116 cells arrest inhibition in G2-M and G0-G1 phases, respectively. Meanwhile, VOA markedly disrupted the mitochondrial membrane potential eliciting mitochondrial dysfunction, decreased ATP production, and intermediated an enhanced accumulation of intracellular reactive oxygen species with a concentration-dependent pattern, accompanied by elevated expression levels of pro-apoptotic related protein Bax, Cyt-C, cleaved caspases 3/8/9 and by diminished Bcl-2, Bid, PRAP and caspases 3/8/9 expression. Further mechanistic studies revealed VOA treatment suppressed the EGFR/PI3K/Akt pathway with the evidence of the decreased phosphorylation proteins of EGFR, PI3K, Akt, and downstream proteins of p-mTOR, p-NF-kB, and p-P70S6. Additionally, molecular dynamics simulations further displayed VOA could enter the EGFR pocket followed by multiple mutual interaction effects. Interestingly, the EGFR activator (NSC228155) could slack the inhibitory capability of VOA on the EGFR/PI3K/Akt pathway as well as VOA-induced impairment of mitochondrial function. Finally, administration of VOA (15, 30 mg/kg every 2 days, i.p., for 16 days) in CT26 syngeneic mice dose-dependently suppressed the neoplastic development without appreciable organ toxicities. Taken together, our study demonstrated that VOA may be a prospective therapeutic agent for the treatment of CRC.

Asunto(s)

RESUMEN

Unlocking the relationship between regional integration and urban green development efficiency (UGDE) is of great importance for boosting regional high-quality development and promoting sustainable urban development patterns. Although studies have analyzed the spatio-temporal evolution and influencing factors of regional integration and UGDE, the impact of regional integration on UGDE remains untested. In this paper, we construct a conceptual framework to analyze how regional integration can influence UGDE through promoting the factors mobility and optimizing the industrial layout. In addition, we further choose the urban agglomeration in the middle reaches of the Yangtze River (UAMRYR), a rapidly growing urban agglomeration in central China, as a case to investigate the spatial spillover effect of regional integration on UGDE from 2003 to 2017. We quantify the UGDE with a random forest model, then estimate the underlying determinants of the UGDE with a spatial Durbin model. Results indicated that (1) the regional integration level and the UGDE index of the UAMRYR and its three sub-urban agglomerations show an increasing trend; (2) for every 1% increase in the level of regional integration, the level of UGDE will increase by 0.8307%; (3) the impact of regional integration on UGDE has obvious regional heterogeneity; while playing a promoting effect in the Wuhan urban agglomeration and the Changsha-Zhuzhou-Xiangtan urban agglomeration, it shows an inhibitory effect in the Poyang Lake urban agglomeration. We conclude that regional integration in agglomeration areas can accelerate the factors flow and optimize the industrial layout for improving UGDE.

Asunto(s)

RESUMEN

A highly efficient potassium carbonate-mediated [3 + 2] cycloaddition reaction of hydrazonoyl chlorides with cinnamic aldehydes to furnish multi-substituted pyrazoles under nontoxic and mild conditions has been developed. A plausible stepwise cycloaddition reaction mechanism is proposed. This protocol featured broad substrate coverage, good functional group tolerance, wide scalability, and operational simplicity, as well as conveniently constructed pyrazole scaffolds.

RESUMEN

BACKGROUND: Breast cancer is one of the malignant tumors with the highest morbidity and mortality rate. Numerous efficient anti-breast cancer drugs are being derived from the development of natural products. Voacamine (VOA), a bisindole alkaloid isolated from Voacanga africana Stapf, possesses various pharmacological and biological activities. PURPOSE: In this study, we investigated the efficacy of VOA against breast cancer cells and elucidated the underlying mechanisms in vitro and in vivo. METHODS: Human breast cancer cell line MCF-7 and mouse breast cancer cell line 4T1 were used to study the underlying anti-cancer mechanisms of VOA. The proliferation was detected by MTT, colony formation, cell proliferation and wound-healing migration assays. Flow cytometry was utilized to determine the level of reactive oxygen species (ROS) cell-cycle, apoptosis and mitochondrial membrane potential. The target proteins were analyzed by Western blot. Molecular docking was performed and scored by AutoDock. Subcutaneous cancer models in mice were established to evaluate the anticancer effects in vivo. RESULT: Our results demonstrated that VOA selectively suppressed breast cancer MCF-7 and 4T1 cells proliferation with IC50 values of 0.99 and 1.48 µM, and significantly inhibited the migration and colony formation of tumor cells. Furthermore, the cell cycle was arrested in the S phase with the decreased expression levels of CDK2, Cyclin A and Cyclin E. Additionally, exposure to VOA dose-dependently brought about dose-dependently the loss of mitochondrial membrane potential (Δψm) and amassment of reactive oxygen species (ROS), resulting in the initiation of the intrinsic apoptotic pathway. Western blot analysis unveiled that VOA significantly activated mitochondrial-associated apoptosis and obviously suppress the PI3K/Akt/mTOR pathway via modulation of related protein expression levels in both tumor cell lines. In tumor-bearing mouse models, administration of VOA dose-dependently inhibited the tumor growth without causing apparent toxicities. CONCLUSION: These findings revealed the novel properties of VOA in promoting apoptosis of breast cancer cells by activating mitochondrial-associated apoptosis signaling pathway and inhibiting PI3K/Akt/mTOR signaling pathway and significantly decreasing tumor size without detecting appreciable toxicity. In summary, the present results demonstrated VOA could be an encouraging drug candidate to cure breast cancer, exhibiting an effective method to exploit unique drugs from natural components.

RESUMEN

BACKGROUND: The evaluation of structural changes after stroke has made great progress; however, it remains difficult to evaluate functional neural changes. NEW METHOD: Here, we report a novel imaging technique that could monitor delayed functional neural circuit injury in an animal model of cerebral ischemia-reperfusion. The changes in 50 mM glutamate-induced biophotonic activities in functional neural circuits in rat brain slices after middle cerebral artery occlusion were investigated with an ultraweak biophoton imaging system. RESULTS: Six hours after ischemia-reperfusion, the rats presented a significant decrease in motion ability together with a large part of the unstained 2,3,5-Triphenyltetrazolium chloride (TTC) area in the ischemia-reperfusion side, whereas the intensity of the biophoton emissions was consistent on both the ischemia-reperfusion and non-ischemic sides of brain slices. Twenty-four hours after reperfusion, the behavior evaluation and TTC staining recovered slightly, and the intensity of the biophoton emissions was weaker on the ischemia-reperfusion side than on the contralateral side. One week after reperfusion, the behavioral test and TTC staining recovered to normal levels; however, the intensity of the biophoton emissions was decreased significantly on both the ischemia-reperfusion and contralateral sides, and such changes were even distinguished in different brain areas, such as the sensory and motor coteries and striatum. CONCLUSION: These findings suggest that delayed functional neural circuit injury induced by cerebral ischemia-reperfusion could be identified with biophoton imaging techniques, providing a novel functional evaluation method for animal models of cerebral ischemia-reperfusion.

Asunto(s)

RESUMEN

Palygorskite (Pal), a clay nanoparticle, has been demonstrated to be a vehicle for drug delivery. Copper has antibacterial properties, and zinc is an essential micronutrient for intestinal health in animals and humans. However, whether copper/zinc-modified Pal (Cu/Zn-Pal) can protect chickens from Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infection remains unclear. In this study, three complexes (Cu/Zn-Pal-1, Cu/Zn-Pal-2, and Cu/Zn-Pal-3) were prepared, and Cu/Zn-Pal-1 was shown to be the most effective at inhibiting the growth of S. Typhimurium in vitro, whereas natural Pal alone had no inhibitory effect. In vivo, Cu/Zn-Pal-1 reduced S. Typhimurium colonization in the intestine of infected chickens and relieved S. Typhimurium-induced organ and intestinal mucosal barrier damage. Moreover, this reduction in Salmonella load attenuated intestinal inflammation and the oxidative stress response in challenged chickens. Additionally, Cu/Zn-Pal-1 modulated the intestinal microbiota in infected chickens, which was characterized by the reduced abundance of Firmicutes and the increased abundance of Proteobacteria and Bacteroidetes. Our results indicated that the Cu/Zn-Pal-1 complex may be an effective feed supplement for reducing S. Typhimurium colonization of the gut.

RESUMEN

Previous studies indicate that the incidence of bacillary dysentery is closely related to meteorological factors. However, the impact of temperature and the spatial heterogeneity of the disease in regions of unbalanced socioeconomic development remains unclear. Therefore, this research collected data for 29,639 daily bacillary dysentery cases in children under 5 years of age, as well as the meteorological variables from China's Beijing-Tianjin-Hebei region, to analyze the spatial pattern of bacillary dysentery and reveal its nonlinear association with temperature. The SatScan method was employed first, to detect the spatial heterogeneity of the disease risk, and then the distributed lag nonlinear model (DLNM) was used to analyze the relationships between the daily minimum, mean, and maximum temperatures and bacillary dysentery in the stratified heterogeneous regions. The results indicated that bacillary dysentery incidence presented statistically significant spatial heterogeneity. The area of highest risk was found to be Beijing and its neighboring regions, which have high population densities. There was also a positive association between bacillary dysentery and temperature. Hotter temperatures were accompanied by higher relative risks. In the most likely spatial cluster region, the excess risk (ER) values for a 1°C rise in minimum, mean, and maximum temperatures above the median were 4.65%, 11.30%, and 19.21%, respectively. The effect of temperature on bacillary dysentery peaked at a lag of 3 to 4 days. The findings of this study will aid risk assessments and early warning systems for bacillary dysentery.

Asunto(s)

RESUMEN

Noroviruses (NoVs) are the leading cause of acute gastroenteritis (AGE) outbreaks. Since 2014, novel genetic variants of NoV have been continuously identified and have caused a sharp increase in the number of AGE outbreaks. The specific geographical distribution and expanding genetic diversity of NoV has posed a challenge to conventional surveillance. Here, we describe the long-term dynamic correlation between NoV distribution in sewage and in the local population through the molecular surveillance of NoV in Guangdong, 2013-2018. The relative viral loads of the GI and GII genotypes in sewage were calculated through RT-PCR. A high-throughput sequencing method and operational taxonomic unit (OTU) clustering pipeline were developed to illustrate the abundances of different genotypes and genetic variants in sewage. Our results showed that the NoV viral loads and the emergence of new variants in sewage were closely associated with NoV outbreak risks in the population. Compared with the outbreaks surveillance, the dominance of the newly emerged variants, GII.P17-GII.17 and GII.P16-GII.2, could be detected one or two months ahead in sewage of a hub city. In addition, the dynamics of pre-epidemic variants, which were rarely detected in clinics, could be captured through sewage surveillance, thus improving our understanding of the origin and evolution of these novel epidemic variants. Our data highlight that sewage surveillance could provide nearly real-time and high-throughput data on NoV circulation in the community. With the advances in sequencing techniques, the sewage surveillance system could also be extended to other related infectious diseases.

Asunto(s)

RESUMEN

In oil and gas production in deep-water high-pressure-high-temperature (HP-HT) wells, wellhead uplift may cause the seal failure of wellbore integrity. Aiming at the oil and gas production stage in deep-water HP-HT wells, we considered the influence of cement sheath cementation and developed a model for calculating the height of wellhead uplifts, and simulation experiments for wellhead uplifts were carried out under the condition of the double pipe string at different cement return heights and multilayer pipe string coupling cementing and noncementing based on a self-developed HP-HT wellhead uplift simulation device. The results show that the elongation of the double pipe string under the condition of a cement return height of 100% is reduced significantly compared with that under the condition of a cement return height of 50%. Also, the maximum elongation of the multilayer pipe string under the condition of coupling and cementing is significantly reduced compared with that under the condition of noncementing. These show that cement sealing has a binding effect on wellhead uplifts. The error between the calculated and the experimental results is less than 10%; thus, the model can be used to predict the wellhead uplift height under different working conditions and provide technical guidance for designing scientific measures to prevent wellhead uplifts.

RESUMEN

Chitosan hydrolysis by chitosanase is one of the most effective methods to produce chitosan oligosaccharides. One of the prerequisites of enzyme fermentation production is to select and breed enzyme-producing cells with good performance. So in the process of fermentation production, the low yield of chitosanase cannot meet the current requirement. In this paper, a strain producing chitosanase was screened and identified, and a novel mutagenesis system (Atmospheric and Room Temperature Plasma (ARTP)) was selected to increase the yield of chitosanase. Then, the fermentation medium was optimized to further improve the enzyme activity of the strain. A strain of Bacillus cereus capable of producing chitosanase was screened and identified from soil samples. A mutant strain of B.cereus was obtained by Atmospheric and Room Temperature Plasma mutagenesis and bioscreening method, and chitosanase activity was 2.49 folds that of the original bacterium. After an optimized fermentation medium, the enzyme activity of the mutant strain was 1.47 folds that of the original bacterium. Combined with all the above optimization experiments, the enzyme activity of mutant strain increased by 3.66 times. The results showed that the Atmospheric and Room Temperature Plasma mutagenesis and bioscreening method could significantly increase the yield of chitosanase in B.cereus, and had little effect on the properties of the enzyme. These findings have potential applications in the mutagenesis of other enzyme-producing microorganisms.

Asunto(s)