[Biosynthetic pathways of triterpenes in medicinal plants and key enzyme genes: a review].

Triterpenes, with high diversity and a wide range of sources, can be found in many medicinal plants. They have been found free or as glycosides/esters by combining with sugars. Most of them act as signaling molecules and function in stress response. They are also the material basis for the therapeutic effect of various medicinal plants. Modern pharmacological research has shown that they have the anti-inflammatory, antibacterial, antiviral, anti-tumor, fertility-regulating, and immunomodulatory effects. They top plant natural products in both quantity and diversity, and among them, tetrachyclic triterpenes and pentachyclic triterpenes are most abundant. The first step of the structural diversification is the cyclization 2,3-oxidosqualene, which is catalyzed by oxidosqualene cyclases(OSCs). Numerous OSCs exist, each with a specific cyclization mechanism, and thus over 100 different cyclic triterpene skeletons have been found in nature. This study reviewed the research on the biosynthetic pathways of triterpenes in medicinal plants, regulatory mechanisms of the pathways, and the key enzymes, and analyzed the expression regulation and structural characteristics of key enzyme genes involved in the synthetic pathways. This study is expected to serve as a reference for further research on triterpenes, such as the directional regulation of metabolic flow and heterologous biosynthesis and lay a basis for the regulation of triterpene synthesis and the selection of high-quality germplasm. This study also provides basic materials for further research and development of triterpenes from medicinal plants.

Influence of clamping stress and duration on the trauma of liver tissue during surgery operation.

BACKGROUND: Tissue grasping damage often occurs in minimally invasive surgery, which would increase the postoperative recovery time and the risk of surgical complications. The purpose of this study was to evaluate the relationship between liver tissue trauma and compression stress magnitude and duration during tissue clamping operation. METHODS: The clamping experiments of liver tissues in vivo were conducted by using a universal soft tissue mechanical testing machine under different clamping stress magnitudes and durations. The rabbit liver was used to simulate human liver. A minimally invasive surgery grasper was used in these tests to simulate the real tissue-surgical operation condition. A pathological grading system was created to quantitatively assess the trauma within the liver tissue. The hyperbolic regression models were utilized to predict the trauma degree of liver tissue. FINDINGS: Obvious hyperemia, hemorrhage, hepatic capsule rupture and inflammatory cell infiltration appeared in the clamping sites of the liver. Assessment results indicated that the trauma degree increased nonlinearly with the increasing clamping stress and duration time. There exist safe thresholds, in which the severe trauma of the studied tissue can be avoided during grasping operation. INTERPRETATION: The results could provide the safety margins and the trauma prediction models for surgeons during grasping and palpation tasks in minimally invasive surgery.

[Knockout of LSD1 Gene by CRISPR/Cas9 System Significantly Inhibited Proliferation and Expression of CD235a in K562 Cells].

OBJECTIVE: To study the effect of LSD1 knock-out on human chronic myeloid leukemia cells(K562 cells). METHODS: The LSD1 gene in K562 cells was knocked-out specifically by using CRISPR/Cas9 system, the single cells were gained by flow cytometric sorting technique, the LSD1+/- and LSD1-/- cell lines were gained after amplificantion and culture, identification of Western blot and sequencing. The MTS assay was used to detect the effect of LSD1 knockout on the proliferation of K562 cells, the flow cytometry was used to examine the expression of K562 cell surface marker after LSD1 knockout. RESULTS: The LSD1 stable knockout cell line of K562 (LSD1+/- and LSD1-/-)were successfully costructed. It was found that knockout of LSD1 significantly inhibited the proliferation of K562 and the expression of CD235a. CONCLUSION: LSD1 plays a key role in the regulation of K562 cell proliferation and CD235a expression.