Cytochrome P450 enzymes represent a class of heme-containing protease widely distributed across the biological kingdom. Endowed with a broad substrate scope, diverse catalytic reaction profiles, high regio- and stereoselectivity toward substrates, and mild catalytic conditions, these enzymes stand out as superior biocatalysts with good potential of application. As one of the primary producers of natural products, Streptomyces harbors a wealth of P450 enzymes and natural product biosynthetic gene clusters (BGCs) in its genome, making it a versatile treasure trove for the generation of bioactive small-molecule compounds. This review summarizes the catalytic reactions by Streptomyces-derived P450 enzymes in natural product biosynthesis and delineates the engineering strategies for addressing the practical application challenges of P450 enzymes, aiming to provide some reference and guidance for in-depth research on P450 enzymes and their applications.

BACKGROUND:Plate fixation is the mainstream method for the surgical treatment of distal femoral fractures.The intramedullary nailing has the advantages of minimally invasive,such as less soft tissue injury and bone blood supply destruction.At the same time,it is a central fixation and has better biomechanical effect.Therefore,retrograde intramedullary nailing has become another option for the internal fixation of distal femoral fractures.OBJECTIVE:The biomechanical characteristics of new retrograde intramedullary nail on lateral femur condyle,common femoral retrograde intramedullary nail,and lateral femur condyle anatomical locking plate for the treatment of A2-type distal femoral fractures were compared using finite element analysis,and the advantages of new retrograde intramedullary nail on lateral femur condyle was studied.METHODS:A new retrograde intramedullary nail on lateral femur condyle was designed,which was inserted into the bone cortex in front of the insertion point of the lateral collateral ligament of the lateral femoral condyle.A CT scan was performed on the lower limb bone of a male volunteer,and a three-dimensional model of the femur was established.The model was then segmented to create a three-dimensional model of a femoral distal A2-type fracture,The three-dimensional models of small(small group),standard type retrograde intramedullary nail on the lateral femoral condyle(standard group),common retrograde intramedullary needle(common group),and lateral femur condyle anatomical locking plate(plate group)were established respectively.The axial stresses of 600,1 800 N and the torsional load of 4 000,8 000 N·mm were applied to the models,and the displacement and stress of femur and the displacement,stress and shear force of internal fixators were observed in each group.RESULTS AND CONCLUSION:(1)When subjected to axial load of 600 and 1 800 N,the femoral peak displacement,the femoral peak stress,and the peak stress of interal fixation in the standard group were the lowest among the four groups.(2)When subjected to torsional load of 4 000 and 8 000 N·mm,the femoral peak displacement and peak displacement of the internal fixation in the standard group were the lowest among the four groups.(3)Compared with femoral lateral condylar locking plate and common retrograde intramedullary needle,the new retrograde intramedullary needle on lateral femur condyle has mechanical advantages of reducing stress concentration and decreasing the risk of internal fixation failure.

ObjectiveTo investigate the effect and mechanism of modified Sini San in ameliorating intestinal mucosal barrier by observing its effects on short chain fatty acids （SCFAs） and high mobility group protein B1 （HMGB1）/receptor of advanced glycation end products （RAGE） signaling pathways in chronic stress rats. MethodsThe 50 male SD rats were randomly divided into control group，model group，low-dose modified Sini San group （7.34 g·kg^-1·d^-1），high-dose modified Sini San group （14.68 g·kg^-1·d^-1），and Fructo-oligosaccharides group （3.15 g·kg^-1·d^-1），with 10 rats in each group. Except for the control group，all other groups were subjected to chronic unpredictable stress/social isolation to create a chronic stress model for 6 weeks. After 4 weeks of modeling，each treatment group was given corresponding drugs by gavage for 2 weeks while modeling. The control group and model group were given the same volume of physiological saline. The effects of Modified Sini San on behaviors，body weight，Bristol score in feces and fecal moisture content in chronic stress rats were observed. Hematoxylin and eosin （HE） staining was used to observe the pathological changes in the cecum. The content of SCFAs in the cecal contents of rats were detected by Gas chromatography-mass spectrometry （GC-MS）. Immunohistochemistry and Western blot were used to detect the expression of HMGB1/RAGE pathway related proteins in cecal tissue. The levels of ZO-1，Occludin，and Claudin-1 in the cecal tissue were detected by enzyme linked immunosorbent assay （ELISA）. ResultsCompared with the model group，the sucrose preference rate，total distance traveled and the number of grid crossings in the open field test of rats in the low-dose modified Sini San group were obviously increased （P<0.05， P<0.01），and the immobility time in the open field test and the immobility time in the forced swimming test of rats in the low-dose and high-dose modified Sini San groups were obviously reduced （P<0.05， P<0.01）. Meanwhile，the Bristol score and fecal moisture content of rats in the low and high dose groups of modified Sini San were obviously increased （P<0.05）. The low-dose group of modified Sini San had intact mucosal layer structure in the cecal tissue and reduced infiltration of inflammatory cells. The content of SCFAs in the cecal contents increased，with a obviously increase in the content of acetic acid，propionic acid，butyric acid，and isovaleric acid （P<0.05， P<0.01） and the expression levels of HMGB1，RAGE，Toll-like receptor 2（TLR2），Toll-like receptor 4（TLR4），tumor necrosis factor-α（TNF-α），and nuclear factor kappa-B p65（NF-κB p65） proteins in cecal tissue were significantly decreased （P<0.05， P<0.01） in low-dose group of modified Sini San. Meanwhile，the contents of ZO-1，Occludin，and Claudin-1 in the cecal tissue were obviously increased （P<0.01） in low-dose group of modified Sini San. ConclusionModified Sini San can improve the function of intestinal mucosal barrier in chronic stress rats by increasing the content of SCFAs in the intestine and inhibiting the HMGB1/RAGE pathway.

ObjectiveTo establish a high-performance liquid chromatography（HPLC） for the quantitative analysis of multiple components in Gegen Qinlian tablets， and to comprehensively evaluate the quality of samples from different manufacturers by integrating chemical pattern recognition and technique for order preference by similarity to ideal solution（TOPSIS）， in order to provide a reference basis for quality evaluation and control of Gegen Qinlian tablets. MethodsHPLC was employed to determine the contents of 10 components in 28 batches of Gegen Qinlian tablets collected from 6 manufacturers， and taking the detection results as variables， SIMCA 14.1 and SPSS 26.0 were employed for cluster analysis（CA）， principal component analysis（PCA）， and orthogonal partial least squares-discriminant analysis（OPLS-DA） to identify key components affecting the quality. Then， TOPSIS analysis was employed to rank the quality of Gegen Qinlian tablets from the 6 manufacturers and establish a comprehensive quality evaluation method. ResultsA quantitative method for Gegen Qinlian tablets was established. After methodological validation， the method was found to be stable and reliable， and could be used for the quantitative analysis of this preparation. The contents of 3′-hydroxy puerarin， puerarin， 3′-methoxy puerarin， daidzein， coptisine hydrochloride， epiberberine， jatrorrhizine hydrochloride， berberine hydrochloride， palmatine hydrochloride and baicalin in 28 batches of samples were 3.58-7.35， 24.88-42.32， 4.20-9.36， 4.33-7.60， 2.52-6.44， 0.93-4.10， 0.58-3.05， 10.68-22.92， 0.82-4.82， 11.73-60.16 mg·g^-1， respectively. Among them， puerarin， berberine hydrochloride and baicalin all met the limit requirements for this preparation specified in the 2025 edition of the Pharmacopoeia of the People's Republic of China. CA and PCA clustered the 28 batches of samples into 5 categories， PCA extracted 2 principal components with a cumulative variance contribution rate of 90.588%， and OPLS-DA screened out 4 differential markers with variable importance in the projection（VIP） values>1.0， namely baicalin， 3′-hydroxy puerarin， coptisine hydrochloride and palmatine hydrochloride， which might be the main components affecting the quality of Gegen Qinlian tablets. TOPSIS analysis showed that the comprehensive score of each evaluation index（C_i） values of different manufacturers were different. Among them， the C_i of manufacturer B was ranked higher， indicating potentially superior quality， while the C_i of manufacturer A was ranked lower， suggesting potentially inferior quality. ConclusionThis study establishes a quantitative method for Gegen Qinlian tablets， and the content uniformity of the same manufacturer is good， while there are differences in the contents of active components among different manufacturers. Through the chemical pattern recognition analysis， it is found that the content differences of Gegen Qinlian tablets may be related to baicalin， 3′-hydroxy puerarin， coptisine hydrochloride and palmatine hydrochloride.

BACKGROUND:Plate fixation is the mainstream method for the surgical treatment of distal femoral fractures.The intramedullary nailing has the advantages of minimally invasive,such as less soft tissue injury and bone blood supply destruction.At the same time,it is a central fixation and has better biomechanical effect.Therefore,retrograde intramedullary nailing has become another option for the internal fixation of distal femoral fractures.OBJECTIVE:The biomechanical characteristics of new retrograde intramedullary nail on lateral femur condyle,common femoral retrograde intramedullary nail,and lateral femur condyle anatomical locking plate for the treatment of A2-type distal femoral fractures were compared using finite element analysis,and the advantages of new retrograde intramedullary nail on lateral femur condyle was studied.METHODS:A new retrograde intramedullary nail on lateral femur condyle was designed,which was inserted into the bone cortex in front of the insertion point of the lateral collateral ligament of the lateral femoral condyle.A CT scan was performed on the lower limb bone of a male volunteer,and a three-dimensional model of the femur was established.The model was then segmented to create a three-dimensional model of a femoral distal A2-type fracture,The three-dimensional models of small(small group),standard type retrograde intramedullary nail on the lateral femoral condyle(standard group),common retrograde intramedullary needle(common group),and lateral femur condyle anatomical locking plate(plate group)were established respectively.The axial stresses of 600,1 800 N and the torsional load of 4 000,8 000 N·mm were applied to the models,and the displacement and stress of femur and the displacement,stress and shear force of internal fixators were observed in each group.RESULTS AND CONCLUSION:(1)When subjected to axial load of 600 and 1 800 N,the femoral peak displacement,the femoral peak stress,and the peak stress of interal fixation in the standard group were the lowest among the four groups.(2)When subjected to torsional load of 4 000 and 8 000 N·mm,the femoral peak displacement and peak displacement of the internal fixation in the standard group were the lowest among the four groups.(3)Compared with femoral lateral condylar locking plate and common retrograde intramedullary needle,the new retrograde intramedullary needle on lateral femur condyle has mechanical advantages of reducing stress concentration and decreasing the risk of internal fixation failure.

Objective: To analyze the epidemiological characteristics of varicella among nursery children in Shenzhen from 2015 to 2024, and to evaluate the impact of optimizing varicella vaccine (VarV) immunization strategies on varicella incidence. Methods: Varicella incidence data for nursery children in Shenzhen from 2015 to 2024 were obtained from the China Disease Prevention and Control Information System. The study period was divided into three phases:one dose self pay VarV (January 2015 to October 2017), two dose self pay VarV (November 2017 to October 2019), and two dose free VarV (November 2019 to December 2024). Interrupted time series (ITS) analysis was conducted to assess changes in the level and trend of varicella incidence associated with each phase of policy implementation. Results: A total of 27 517 varicella cases was reported among nursery children from 2015 to 2024, with an average annual incidence of 514.01/100 000. During the same period, 136 clustered outbreaks were reported in nursery institutions, involving a cumulative total of 1 091 cases. ITS analysis showed that during the self pay 1 dose stage, the varicella incidence among nursery children showed an upward trend, with an average monthly increase of 2.58/100 000 (95% CI =2.21/ 100 000 -2.95/100 000, P <0.01). After the implementation of the self pay 2 dose strategy, the incidence decreased, with a change in incidence of -26.12/100 000 (95% CI =-37.30/100 000 to -14.94/100 000) and a change in slope of -2.65/100 000 (95% CI = -3.38/100 000 to -1.93/100 000)(all P <0.01). After the implementation of the free 2 dose strategy, the incidence decreased further, with a change in incidence of -40.03/100 000 (95% CI =-50.39/100 000 to -29.66/100 000, P <0.01) and a change in slope of -0.56/100 000 (95% CI =-1.20/100 000-0.08/100 000, P =0.09). Conclusion The gradual optimization of the VarV vaccination strategy in Shenzhen from self pay 1 dose to free 2 dose has significantly reduced the varicella incidence among nursery children, demonstrating good short term control and long term intervention effectiveness.

[Objective] To analyze the influencing factors of repeat blood donor lapsing using a zero-inflated poisson regression model (ZIP). [Methods] The blood donation behavior of 12 498 whole blood donors from 2020 was tracked until December 31, 2023. The factors influencing the frequency of blood donations in a given year was analyzed using ZIP, and donors with 0 blood donation in that year were considered to have lapsed. The changes in relevant influencing factors associated with each blood donation were measured and modeled for analysis. [Results] The zero-inflated part of ZIP showed that the risk of lapsing of male blood donors was 2.24 times that of female blood donors (OR 95% CI:1.864-2.696, P<0.001); the risk of lapsing of the 35-44 age group and over 45 age group was respectively 40% (OR 95% CI:0.455-0.790, P<0.001) and 61%(OR 95% CI:0.268-0.578, P<0.001) lower than that of the under 25 age group; the risk of lapsing for those who have donated blood twice and ≥3 times was respectively 50% (OR 95% CI:0.405-0.609, P<0.001) and 81% (OR 95% CI:0.154-0.225, P<0.001) lower than that of first-time donors; the risk of lapsing of those with junior high or high school education was 1.2 times that of those with a college degree or higher (OR 95% CI:1.033-1.384, P<0.05); the risk of lapsing for the divorced group was 2.02 times that of the married group (OR 95% CI:1.445-2.820, P<0.001); the risk of lapsing for those with an income (Yuan) of 10 000 to 50 000, 50 000 to 100 000 and more than 100 000 was respectively 0.67 (OR 95% CI:0.552-0.818, P<0.001), 0.72 (OR 95% CI:0.591-0.884, P=0.002) and 0.67 (OR 95% CI:0.535-0.834, P<0.001) times that of those with an income (Yuan) of less than 10 000. The results of the Poisson part are consistent with the results of the zero-inflated part in terms of age and education level. [Conclusion] Blood donor lapsing is overall related to factors such as gender, age, donation frequency, education, marital status and family income. It's essential to care for those blood donors prone to lapse to retain more regular blood donors.

BACKGROUND:Early exercise treatment is the main prevention way for traumatic joint contracture and is also a research focus.Swimming may be a potential intervention for joint contracture due to the special physical properties of water. OBJECTIVE:To explore the effects of swimming on the development of joint contracture in a rat model and study its mechanisms. METHODS:Twenty-four Sprague-Dawley rats were randomly divided into a blank control group(n=8)and a joint contracture group(n=16).After the surgical operation of knee joint contracture rat models,the joint contracture group was randomly subdivided into a surgical control group(n=8)and a swimming treatment group(n=8).Swimming started in the swimming treatment group in the second week after surgery and lasted for a total of 5 weeks.At the 6th week after surgery,the body mass,knee joint range of motion,and quadriceps diameter were tested,and the diameter/body mass index was calculated.Hematoxylin-eosin staining was performed to detect the pathological changes in the knee joint capsule and quadriceps muscle,and Masson staining was used to observe fibrotic changes in the knee joint capsule.Furthermore,the protein expression of transforming growth factor β1 and type I collagen in the knee joint capsule was quantified by immunohistochemical assay and western blot was performed to detect the protein expression of MuRF1 in the quadriceps femoris. RESULTS AND CONCLUSION:Compared with the blank control group,the knee range of motion decreased in the surgical control and swimming treatment groups(P<0.01),and knee extension deficit and arthrogenic extension deficit were significantly increased(P<0.01),the diameter of the quadriceps muscle was decreased(P<0.01),the joint capsule showed significant fibrosis,the quadriceps muscle was atrophied,and the diameter/body mass index was decreased(P<0.01).Compared with the surgical control group,the swimming treatment group showed a significant increase in knee joint range of motion and quadriceps diameter(P<0.01),and significant improvement in joint capsule fibrosis and quadriceps atrophy.Compared with the blank control group,collagen fiber content and expression of transforming growth factor β1 and type I collagen were increased in the joint capsule of rats in both the surgical control group and the swimming treatment group(P<0.01).Compared with the surgical control group,collagen fiber content and expression of transforming growth factor β1 and type I collagen protein in the joint capsule were decreased in the swimming treatment group.Compared with the blank control group,the expression of MuRF1 protein in the quadriceps muscle of rats in the surgical control group and the swimming treatment group was increased(P<0.05).Compared with the surgical control group,the expression of MuRF1 protein in the quadriceps muscle of rats in the swimming treatment group was decreased(P<0.05).To conclude,early swimming intervention reduces transforming growth factor β1 and type I collagen expression in the joint capsule of traumatic joint contracture rats,decreases MuRF1 expression in the quadriceps muscle,and increases joint range of motion and quadriceps diameter,thereby inhibiting the development of joint contracture.

BACKGROUND:Dysfunction of macrophage efferocytosis can induce local and systemic inflammatory damage and is associated with a variety of obesity-related metabolic diseases.Moreover,compounds targeting efferocytosis have shown good therapeutic effects. OBJECTIVE:By reviewing the effects of obesity on macrophage efferocytosis,to analyze the key mechanism by which obesity inhibits efferocytosis,to summarize the research progress in compounds targeting efferocytosis to treat obesity-related metabolic diseases,so as to provide new ideas for fully understanding efferocytosis and its relationship with metabolic diseases,aiming to provide new strategies for disease prevention and treatment. METHODS:The English search terms were"efferocytosis,metabolism,obesity,obese,atherosclerosis,non-alcoholic steatohepatitis,neurodegeneration,tumor,osteoarthritis,diabetes,compound,medicine,treatment,"which were used for literature retrieval in PubMed and Web of Science.The Chinese search term was"efferocytosis,"which was used for literature retrieval in CNKI,VIP and WanFang datebases.Ninety-nine papers were finally included in the review analysis after a rigorous screening process. RESULTS AND CONCLUSION:In the process of efferocytosis,the"Find me"and"Eat me"processes involving a large number of apoptotic cell derived factors are mainly regulated by apoptotic cells.The efferocytosis factor involved in cytoskeletal remodeling and digestion are mainly derived from macrophages,which are crucial for efferocytosis activity.These results suggest that the"Find me"and"Eat me"factors mainly reflect the condition of apoptosis,and it is more scientific to select the expression of factors involved in cytoskeletal remodeling and digestion when evaluating the efferocytosis activity of macrophages.Obesity inhibits efferocytosis,and shows an inhibitory effect on most digestive factors,but has a stress-induced activation effect on most"Find me,""Eat me"and cytoskeletal recombination factors,which further indicates the decisive effect of digestive stage on efferocytosis and suggests that it is not reliable for some studies to evaluate the efferocytosis based on the increased expression of"Find me"and"Eat me"factors.Targeting cytokines in the digestive phase may be more effective when discussing future intervention strategies targeting macrophages efferocytosis.The efferocytosis activators of macrophages are effective in the treatment of various metabolic diseases,but the efferocytosis inhibitors in tumor tissue show good anticancer effects,suggesting that the role of efferocytosis should be rationally evaluated according to the characteristics of tissue inflammation.Efferocytosis is a relatively new concept proposed in 2003,with a short research history and complex efferocytosis factors.Current studies on obesity and efferocytosis only involve a tip of the iceberg and most of them are at a superficial level and a large number of scientific experiments are needed to further validate the mechanisms.

Objective:To investigate the feasibility of deep learning reconstruction (DLR) algorithm combined with a dual-low protocol (low radiation dose and low contrast medium dose) for thoracoabdominal aortic CT angiography (CTA).Methods:This cross-sectional study prospectively enrolled 56 patients suspected of aortic diseases who underwent aortic CTA at China-Japan Friendship Hospital from June 2023 to June 2024. All patients were randomly divided into two groups: Group A (28 cases) underwent CTA with a tube voltage of 100 kVp, automatic tube current modulation (noise index=10), and a contrast agent dose of 80 ml (flow rate 5 ml/s), with images reconstructed using the three-dimensional adaptive iterative dose reduction algorithm (AIDR). Group B (28 cases) underwent CTA with a tube voltage of 80 kVp, automatic tube current modulation (noise index=25), and a contrast agent dose of 40 ml (flow rate 3.5 ml/s), with images reconstructed using either the deep learning reconstruction algorithm-Advanced intelligent Clear-IQ Engine (AiCE subgroup) or the AIDR (AIDR subgroup). Two physicians evaluated the image quality of the three groups subjectively and objectively. Objective evaluation metrics included CT values, image noise (SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) at the ascending aorta, carina-level descending aorta, celiac trunk-origin abdominal aorta, and common iliac bifurcation abdominal aorta carina. Subjective evaluation metrics included image quality and noise scores. Comparisons among the three datasets (Group A, AiCE subgroup, AIDR subgroup) were performed using one-way ANOVA or the Kruskal-Wallis test, with appropriate post-hoc tests for pairwise comparisons.Results:No significant differences were observed in CT values of the ascending aorta, descending aorta, and abdominal aorta between Group A and the AiCE subgroup or the AIDR subgroup ( P0.05). However, significant overall differences were found in SD, SNR, and CNR values for the ascending aorta, descending aorta, and abdominal aorta ( P0.05). Pairwise comparisons revealed that, except for no significant differences in SD, SNR, and CNR values of the ascending and descending aorta between Group A and the AiCE subgroup, and no significant difference in SNR values of the ascending and abdominal aorta between Group A and the AIDR subgroup ( P0.05), all other intergroup comparisons showed statistically significant differences ( P0.05). Significant overall differences were also observed in image quality and noise scores between Group A and the AiCE and AIDR subgroups ( P0.05). Except for no significant differences in image quality and noise scores between Group A and the AiCE subgroup ( P0.05), all other pairwise comparisons showed statistically significant differences ( P0.05). Conclusions:The application of deep learning reconstruction algorithm combined with a dual-low protocol in thoracoabdominal aortic CTA can reduce radiation dose and contrast agent dose while maintaining diagnostic image quality, demonstrating significant clinical value for widespread adoption.