In recent years,with the continuous progress of DNA extraction and detection technology,cell-free DNA(cfDNA)has been widely used in the life science field,and its potential application value in forensic identification is becoming more and more obvious.This paper reviews the concept,formation mechanism,and classification of cfDNA,etc.,and describes the latest research progress of cfDNA in personal identification of crime scene touch DNA samples and non-invasive prenatal pater-nity testing(NIPPT).Meanwhile,this paper summarizes the potential application of cfDNA in injury inference,and discusses the advantages and disadvantages of common cfDNA analysis methods and techniques,and its application prospects,to provide a new idea for the wide application of cfDNA in the field of forensic science.

Celastrol and wilforlide A are the main active triterpenoids of the traditional Chinese medicine Lei Gong Teng, which have anti-tumour, anti-inflammatory and immunosuppressive activities, and are the material basis for the clinical efficacy of Lei Gong Teng-related Chinese medicinal preparations. By analysing the biosynthetic pathway of active ingredients, optimizing genetic elements and utilizing "cell factory" to produce triterpenoids heterologously will be an effective way to obtain from Tripterygium wilfordii in the future in a "low-cost and high-efficient" manner. CYP712Ks are the first cytochrome P450s involved in the skeleton modification of friedelane-type and oleanane-type triterpenoids in T. wilfordii, and they can catalyse the generation of polpunonic acid from friedelin and 3-epi-katonic acid from β-amyrin by carboxylation at C-29 position. In this study, four multifunctional TwCYP712K1/2/3/5 were used to clarify the catalytic function and substrate selection preference using in vivo functional characterization in Saccharomyces cerevisiae. The spatial structure of the protein-substrate binding was clarified through homology modeling and molecular docking, and then the differential amino acids in the active pocket of the protein were mutated to clarify the crucial amino acids determining the catalytic function and the selection of substrate structure. A total of 63 mutant elements were constructed, and the amino acid sites affecting the carboxylation function of TwCYP712Ks were analyzed. In particular, the key amino acids affecting the substrate selectivity of TwCYP712K2 towards oleanane-type and friedelane-type triterpenoids were revealed and the TwCYP712K2^F127I and TwCYP712K2^A227T mutants would result in a reversal of the product ratio. In conclusion, four proteins of TwCYP712Ks were semi-rationally designed by homologous protein alignment and mutual mutation to elucidate multiple amino acid sites determining the catalytic function of the proteins, and a series of activity-enhancing or altering mutants were obtained, which provide abundant catalytic elements for the biosynthesis of active triterpenoids from T. wilfordii, and the mechanism of carboxylation in the C-29 position was initially elucidated.

Four pyrazines were isolated from the n-butanol fraction of Hypecoum erectum L. by using various chromatographic methods, including MCI gel, ODS, silica gel and semi-preparative HPLC. The structures of the isolated compounds were identified as hyperectpyrazin A (1), 1′S-(6-methylpyrazin-2-yl)-ethane-1′,2′-diol (2), 2-hydroxymethyl-6-methylpyrazin (3) and pyrazine-2-carboxylic acid (4) by spectroscopy methods (1D NMR, 2D NMR, UV, IR, MS, etc.). The absolute configuration of compound 2 was determined by using the Mo₂(OAc)₄ induced CD analysis for the first time. Compound 1 was a new compound, compounds 2-4 were isolated from H. erectum for the first time. Compounds 1-4 were evaluated for their inhibition against acetylcholinesterase and nitric oxide generation induced by lipopolysaccharide-RAW264.7 macrophage cells. At a concentration of 50 μmol·L^-1, compounds 2 and 4 displayed inhibitory effects on acetylcholinesterase with the inhibition rates of 44.40% and 43.99%, respectively.

Objective To observe the efficacy and safety of Morinda officinalis oligosaccharides in the continuation treatment of mild and moderate depression.Methods An open,single-arm,multi-center design was adopted in our study.Adult patients with mild and moderate depression who had received acute treatment of Morinda officinalis oligosaccharides were enrolled and continue to receive Morinda officinalis oligosaccharides capsules for 24 weeks,the dose remained unchanged during continuation treatment.The remission rate,recurrence rate,recurrence time,and the change from baseline to endpoint of Hamilton Depression Scale(HAMD),Hamilton Anxiety Scale(HAMA),Clinical Global Impression-Severity(CGI-S)and Arizona Sexual Experience Scale(ASEX)were evaluated.The incidence of treatment-related adverse events was reported.Results The scores of HAMD-17 at baseline and after treatment were 6.60±1.87 and 5.85±4.18,scores of HAMA were 6.36±3.02 and 4.93±3.09,scores of CGI-S were 1.49±0.56 and 1.29±0.81,scores of ASEX were 15.92±4.72 and 15.57±5.26,with significant difference(P＜0.05).After continuation treatment,the remission rate was 54.59％(202 cases/370 cases),and the recurrence rate was 6.49％(24 cases/370 cases),the recurrence time was(64.67±42.47)days.The incidence of treatment-related adverse events was 15.35％(64 cases/417 cases).Conclusion Morinda officinalis oligosaccharides capsules can be effectively used for the continuation treatment of mild and moderate depression,and are well tolerated and safe.

Objective To evaluate the safety,tolerability and pharmacokinetic profiles of naldemedine in Chinese healthy adult subjects after single and multiple administrations.Methods After single and multiple oral administrations of naldemedine to 10 healthy Chinese subjects,the plasma concentrations of naldemedine and its metabolite(nor-naldemedine)were measured by liquid chromatography-mass spectrometry,and the pharmacokinetic parameters were calculated by Phoenix WinNonlin 8.3.1 software.Results Compared with single administration,naldemedine showed no significant change in the tmax(1.06 h for single and 1.08 h for multiple)and Cmax(4.16 ng·mL-1 for single and 4.11 ng·mL-1 for multiple),higher AUC0-τ than that of single(23.88 ng·h·mL-1 for single and 28.93 ng·h·mL-1 for multiple),slightly prolonged t1/2(9.26 h for single,12.50 h for multiple),there was a slight drug accumulation after multiple doses(accumulation ratio of 0.99 for Cmax and 1.22 for AUC);t1/2(18.10 h for single,29.30 h for multiple),Cmax(0.19 ng·mL-1 for single,0.38 ng·mL-1 for multiple),and AUC0-τ(3.13 ng·h·mL-1 for single,6.02 ng·h·mL-1 for multiple)were all significantly elevated with nor-naldemedine,and the tmax(single was 3.49 h and multiple was 3.56 h)did not change significantly.The Cmax ratio and AUC ratio of metabolites to naldemedine were significantly elevated,and accumulation was present after multiple administrations(accumulation ratio of 2.01 for Cmax and 1.95 for AUC).All adverse events that occurred after treatment were mild.Conclusion After multiple oral administrations of 0.2 mg naldemedine tablets to Chinese healthy subjects(single dose on day 1 and once daily on days 4-13),the drug was eliminated rapidly with mild accumulation,and reached a steady state before the second dose of the multiple-dosing phase,and the product has a favorable safety and tolerability profiles.

Objective To explore the relevant risk factors of H.pylori infection,and provide reference for prevention and treatment of H.pylori in this area,and further provide theoretical basis for the prevention and treatment of gastric cancer.Methods A total of 1200 residents in four districts of Haikou city were investigated by questionnaire and urea 14 C breath test by holistic stratified random sampling to calculate the population infection rate and analyze the risk factors of infection.Results The total infection rate was 32.5％,which was lower than the national H.pylori infection rate.No consumption of fruits and vegetables,no habit of washing hands before meals,and people with gastrointestinal symptoms,are independent risk factors of H.pylori infection.No consumption of pickled products is of great significance to prevent H.pylori infection.Conclusion The prevalence of H.pylori infection in the population of Haikou is lower than the national average,and H.pylori infection is closely related to the poor living habits of residents.

Secondary organic aerosol(SOA)produced by photooxidation of styrene and other aromatic compounds is a major part of fine particles in urban atmosphere.In this study,the measurement of component and content of SOA formed from photooxidation of styrene in smog chamber using synchronous radiation vacuum-ultraviolet photoionization aerosol mass spectrometer(VUV-PIAMS)was conducted.Photoionization mass spectra of styrene SOA was detected by synchrotron radiation photon with 10.5 eV,and the proportion of main components was quantified based on the peak area of each ion peak.The photoionization efficiency curve of ion peak was obtained under synchrotron radiation photons in the range from 7.5 to 11.5 eV,and then the ionization potential was acquired for qualitative analysis of the component structure.The results showed that the photoionization mass spectra of styrene SOA mainly contained ion peaks at m/z 106,108,120 and 122,and the ionization potentials of each peak were(9.41±0.03)eV,(8.93±0.03)eV,(9.24±0.03)eV and(9.25±0.03)eV,respectively.Combined with quantum chemistry calculation and off-line measurement verification of infrared absorption spectra and electrospray ionization mass spectra,it was determined that benzaldehyde,benzyl alcohol,4-vinylphenol and benzoic acid were main components of styrene SOA,accounting for 32.5%,17.5%,25%and 15%of the measured components,respectively,and the generated quantity ratio was 13∶7∶10∶6.VUV-PIAMS could overcome the disadvantages of off-line method,and could on-line detect component and content of SOA,proving a useful tool to measure the chemical components and reveal the formation process of SOA particles.

Objective To investigate the distribution of traditional Chinese medicine(TCM)syndromes in the patients with acute cerebral infarction,and to analyze the correlation of TCM syndromes with collateral circulation,cerebral blood perfusion and prognosis.Methods A total of 300 patients with acute cerebral infarction were selected.All patients underwent head-neck CT angiography(CTA)and CT perfusion imaging(CTP),and then were followed up for 30 days.The prognosis was evaluated by modified Rankin Scale(MRS)score.In addition,the dynamic evolution of TCM syndromes was observed to explore the correlation of TCM syndromes with collateral circulation,cerebral blood flow perfusion in the lesion area and prognosis.Logistic regression analysis was used to explore the influences of TCM syndromes,blood flow perfusion and collateral circulation establishment on stroke outcomes.Results(1)Highest incidences of syndrome elements of phlegm,blood stasis and wind were presented in ACI patients.The syndrome element of qi deficiency was predominated in the patients with anterior/posterior communicating artery opening and extracranial-to-intracranial collateral circulation establishment.On the first day of onset,the incidence of qi deficiency syndrome element in the good collateral circulation group was lower than that in the poor collateral circulation group(P＜0.05).On the 30th day after onset,the incidences of qi deficiency syndrome element and phlegm syndrome element in the good collateral circulation group were significantly lower than those in the poor collateral circulation group(P＜0.01).The results of correlation analysis showed that the score of qi deficiency was negatively correlated with regional cerebral blood volume(rCBV)of region of interest(r=-0.472,P＜0.05),and the score of yin deficiency was positively correlated with rCBV(r=-0.557,P＜0.01)on the first day of onset.The incidence of qi deficiency in the lesion area was relatively high in the patients of decreased rCBV(rCBV＜1.0 score)group(P＜0.01),while the incidence of yin deficiency in the lesion area was relatively high in the patients of elevated rCBV(rCBV＞1.0 score)group(P＜0.05).(2)The distribution of syndrome elements on the first day of onset showed that the incidence of qi deficiency syndrome element in the poor prognosis group was significantly higher than that in the good prognosis group(P＜0.01);on the 30th day after onset,the incidences of qi deficiency syndrome element and phlegm syndrome element in the good prognosis group was significantly lower than those in the poor prognosis group(P＜0.05 or P＜0.01).The incidence of phlegm syndrome element in the good prognosis group was significantly reduced on the 30th day after onset compared with that on the first day of onset(χ2=7.409,P＜0.01),while there was no significant difference shown in the poor prognosis group(P＞0.05).(3)Logistic regression analysis showed that syndrome elements(qi deficiency,phlegm),collateral circulation grading,and rCBV in the lesion area were the independent risk factors for stroke outcomes.Conclusion The acute cerebral infarction patients with poor collateral circulation,decreased blood perfusion and poor prognosis are predominated by qi deficiency syndrome element.Moreover,phlegm syndrome element is presented in the patients with poor prognosis throughout the course of disease.It is indicated that qi deficiency syndrome element and phlegm syndrome element play an important role in the pathogenesis and progression of acute cerebral infarction.

Objective To design a novel oxygenator to solve the existing problems of extracorporeal membrane oxygenation(ECMO)machine in high transmembrane pressure difference,low efficiency of blood oxygen exchange and susceptibility to thrombosis.Methods The main body of the oxygenator vascular access flow field was gifted with a flat cylindrical shape.The topology of the vascular access was modeled in three dimensions,and the whole flow field was cut into a blood inlet section,an inlet buffer,a heat exchange zone,a blood oxygen exchange zone,an outlet buffer and a blood outlet section.The oxygenator was compared with Quadrox oxygenator by means of ANSYS FLUENT-based simulation and prototype experiments.Results Simulation calculations showed the oxygenator designed was comparable to the clinically used ones in general,and gained advantages in transmembrane pressure difference,blood oxygen exchange and flow uniformity.Experimental results indicated that the oxygenator behaved better than Quadrox oxygenator in transmembrane pressure difference and blood oxygen exchange.Conclusion The oxygenator has advantages in transmem-brane pressure difference,temperature change,blood oxygen ex-change and low probability of thrombosis.[Chinese Medical Equipment Journal,2024,45(3):23-28]

Objective To analyze the stresses in implanted titanium solid and bone trabecular prosthesis hip replacements.Methods A femur model was built inversely based on Mimics software,and optimized using Geomagic software,and then materialized by SolidWorks software.The osteotomized femur was assembled with the metal femoral stem to form a model,and then the model was imported into ABAQUS for finite element calculation.The upper femur was divided into four regions in different states of integration:medial proximal point(small trochanter region),lateral proximal region(large trochanter region),proximal point of the femoral stem(region around the mid-portion of the styloid process)and distal region(around the end of the styloid process and distal portion).Calculations were carried out over the femoral stresses before and after implantation of titanium solid and trabecular prostheses under gait and stair-climbing loads and the interfacial stresses when the region was unintegrated.The type of deformation at the bone interface was analyzed by means of a stress ellipsoid.Results At the small trochanter region,the stress shielding rates of the trabecular prosthesis under gait and stair climbing loads were reduced by 20.5％and 14.7％compared to the titanium solid prosthesis,respectively.In case of different integration states of the titanium solid prosthesis,the interface tensile stresses under the gait and stair climbing loads were up to 10.842 MPa and 12.900 MPa,and the shear stresses reached 7.050 MPa and 6.805 MPa,respectively;in case of different integration states of the trabecular prosthesis,the interface tensile stresses under the gait and stair climbing loads were up to 3.858 MPa and 4.389 MPa,and the shear stresses reached 4.156 MPa and 3.854 MPa,respectively.Under the 2 different loads,the inboard shear stress ellipsoid of the interface opened toward the sides and the bone interface showed tensile deformation;the outboard shear stress ellipsoid of the interface opened up and down and had compressive deformation.Conclusion After total hip arthroplasty,the overall performance of the trabecular prosthesis is better than that of the titanium solid prosthesis.The unintegrated edges of the prosthesis-bone interface are susceptible to stress concentrations and distortion which may result in occurrence of failures.[Chinese Medical Equipment Journal,2024,45(3):29-35]