Browsing by Author "Zhang, Zhen"

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    Optimization of the whole-cell catalytic activity of recombinant Escherichia coli cells with surface-immobilized organophosphorus hydrolase.
    (2013-04) Zhang, Hongxing; Li, Qianqian; Ye, Ting; Zhang, Zhen; Li, Lin
    Previous studies have verified the feasibility of using Escherichia coli systems that display organophosphorous hydrolase (OPH) on the cell surface as whole-cell catalysts. However, the inefficient display of the enzyme on cell surfaces remains unaddressed. In the present study, multiple optimization experiments on full-length and truncated ice nucleation protein anchors, E. coli host cells, culture media, and culture conditions were performed to optimize whole-cell OPH enzymatic activity. The results show that apart from the dramatic effect of isopropyl-b-d-thiogalactoside concentration and culture temperature, the coordination between the anchor protein, culture media, and host cells is essential for highly efficient OPH display. Under optimal conditions, namely, culturing in M9 medium, 20 °C induction temperature, 0.1 mmol l-1 IPTG, and 100 μmol l-1 Co2+, the engineered E. coli strain MB109-406 that expresses the fusion enzyme InaK-N-OPH exhibited a whole-cell OPH activity of 0.62 U mg-1 ?cell d.wt. This result is much higher than that of several currently available OPH-displaying systems, which shows the potential of the current system for further large-scale industrial or environmental applications.
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    Preparation and Drug Release Mechanism of Time Controlled Explosive Pulsatile Tablets with Ethylcellulose Coating
    (Lawarence Press Pvt. Ltd., 2020-04) Ouyang, Jiabi; Wang, Xingli; Yang, Mohui; Tan, Yani; Zhang, Zhen; Li, Sha
    Background The time rhythm of human body is associated with the occurrence and development of manydiseases, and it also affects the efficacy and pharmacokinetic characteristics of the corresponding therapeuticdrugs. Therefore, the chronopharmacological drug delivery system has potential applications. Aim In this work, it is proposed to develop a kind of pulsatile release tablet of simple structure and preparingprocess, thus to provide an alternative drug delivery system for therapeutic agents used in treatment of diseasesof typical onset biorhythm at period inconvenient to take drug.Methods Metoprolol tartrate (MT), a drug widely used clinically to treat cardiovascular diseases was selected asa model drug for developing pulsatile tablets of time-controlled explosive system (TES). The MT pulsatile tabletswere ethyl cellulose (EC) coating tablets produced by pan coating process, and the core tablets were preparedby direct compression. The formulation and process was optimized by single factor test and orthogonal design.Also, the pulsatile release mechanism of the tablets was discussed through investigating the water absorptionand swelling capacity of tablets as well as the mechanical properties of EC free film.Results A kind of pulsatile tablets of MT were developed with a drug release lag time around 7 h and a fastrelease of drug after lag time. When the swelling force of core tablet caused by water uptake was high enoughover the tensile strength of EC coating film, the MT pulsatile tablets demonstrated a shell-type exploding rupturedue to the great rigidity and weak flexibility of EC film, and then a fast pulsatile release of drug was observed.Both the swelling capacity of core tablet and the thickness of coating film together controlled the lag time of drugrelease. The lag time showed a good linear relationship with the thickness of coating film (r = 0.9984, P < 0.01).The sort and amount of fillers and disintegrants dominated the release behaviour after lag time.Conclusion The developed MT pulsatile tablets can exert a timely release of drug before peak onset period ofhypertension and angina pectoris early in the morning after drug taking around 22:00 P.M the night before. Thegood linear relationship between lag time and coating thickness enabled the pulsatile tablets to be used fordelivery of other therapeutic agents of similar chronotherapy demand by adjusting the coating thickness toachieve the appropriate lag time of drug release to match the different high attack rhythm of the exact diseases.
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    Primary epithelioid trophoblastic tumor of the lung: A case report
    (Wolters Kluwer – Medknow, 2024-06) Zhang, Qiongying; Sun, Wenwen; Zhang, Zhen; Li, Jianmin
    Primary epithelioid trophoblastic tumor (ETT) of the lung is exceedingly rare. Only about three cases have been reported in Pubmed and worldwide literature. We presented a case of multiple primary ETT of the lung occurring in a 33?year?old Chinese female patient. Comprehensive physical examinations revealed no evidence of a primary lesion on the uterus or cervix uteri. Microscopic examination of the tumor demonstrated ETT of the lung, which was confirmed by immunohistochemical staining and declining level of beta?human choriogonadotropin (??HCG) after the operation. Our case revealed that the ETT can occur in the lung and should be considered when a female had a tumor of lung with increasing ??HCG.