ObjectiveTo express and purify the endolysin PlyL from the Bacillus anthracis prophage LambdaBa02 in prokaryotic cells, and to explore its role in the detection of Bacillus anthracis, so as to provide a novel strategy for the specific and rapid detection of Bacillus anthracis.MethodsAccording to the sequence of Bacillus anthracis vaccine strain CVCC40205 registered in GenBank, the plyL gene was amplified by PCR with plyL gene-specific primers and inserted into the prokaryotic expression vector pET28a(+) to construct the recombinant expression plasmid pET28a(+)-His-plyL, which was then transformed into E.coli BL21(DE3) and induced by IPTG. The induced expression conditions were optimized to enhance soluble expression, and the recombinant PlyL protein was purified via nickel-affinity chromatography. The lytic activity of recombinant PlyL protein was assessed by measuring absorbance values, and an ELISA method was established to evaluate the sensitivity and specificity of Bacillus anthracis detection.ResultsThe recombinant expression plasmid pET28a(+)-His-plyL was confirmed to be correctly constructed by NdeⅠ and XhoⅠ double digestion and sequencing. The optimal induction conditions were 0. 5 mmol/L IPTG at 16 ℃ for 16 h. The relative molecular mass of the expressed recombinant PlyL protein was about 28 600. After purification and concentration, the final concentration of the protein was2. 55 mg/mL, and the purity reached 80. 6%. The purified recombinant PlyL protein could reduce the A_(600)value of Bacillus anthracis culture solution. The sensitivity of the preliminarily established ELISA method for detecting Bacillus anthracis was1 × 10~3 CFU/mL, and there was no cross-reactivity against closely related strains such as Bacillus cereus and Bacillus thuringiensis(P < 0. 000 1).ConclusionThe recombinant PlyL protein was successfully expressed and purified in prokaryotic cells, which exhibits both efficient lytic activity and species specificity, making it a promising novel tool for the rapid detection of Bacillus anthracis.

BACKGROUND:Intervertebral disc degeneration is a condition caused by the combined effects of various factors,such as cellular apoptosis,oxidative stress,and inflammatory responses.Currently,it is believed that the core of this condition lies in the degeneration and apoptosis of nucleus pulposus cells(NPCs).However,the specific pathological mechanisms remain unclear. OBJECTIVE:By investigating the expression of the phosphatidylinositol-3 kinase(PI3K)/protein kinase B(Akt)/hypoxia-inducible factor 1-alpha(HIF-1α)signaling pathway and the apoptosis of NPCs under different oxygen concentrations,to clarify the biological characteristics of NPCs under varying oxygen levels,and to explore the mechanisms of intervertebral disc degeneration. METHODS:Normal and degenerated NPCs were collected.The second-generation cells were used for imaging identification.The third-generation cells were cultured in the following conditions:37℃,air,100%humidity.Leibovitz's medium containing 100 μmol/L CoCl2 and 10%fetal bovine serum medium containing 100 μmol/L H2O2 were used to create distinct oxygen concentration environments for the third-generation cells,allowing for the investigation of cellular responses and behaviors under normal,low oxygen,and oxidative stress conditions.The third-generation cells were divided into six groups:normal NPCs+hypoxia,normal NPCs+normoxia,normal NPCs+oxidative stress,degenerated NPCs+hypoxia,degenerated NPCs+normoxia,and degenerated NPCs+oxidative stress groups.Cell viability and proliferation were assessed using the cell counting kit-8 method.Cell apoptosis was detected using flow cytometry.RT-PCR and western blot assay were utilized to examine the protein and mRNA expression levels of PI3K,AKT,and HIF-1α. RESULTS AND CONCLUSION:At different oxygen concentrations,the cell proliferation rate of both normal and degenerated NPCs decreased as the oxygen concentration increased.Conversely,the apoptosis rate increased as the oxygen concentration rose(P<0.05).With the normal NPCs+hypoxia group as the control group,the effect of degenerated NPCs on the apoptosis rate was highly significant(P<0.001).Oxygen concentration had a highly significant impact on both NPC proliferation rate and apoptosis rate(P<0.001).The interaction between cell degeneration and oxygen concentration significantly affected both NPC proliferation and apoptosis rates(P<0.05).At different oxygen concentrations,the protein and mRNA expression levels of PI3K,AKT,and HIF-1α in normal NPCs were highest under low oxygen concentration,followed by oxidative stress environment,and lowest under normoxia.In degenerated NPCs,the protein and mRNA expression levels of PI3K,AKT,and HIF-1α decreasd as the oxygen concentration increased.The protein and mRNA expression levels of PI3K and Akt in normal NPCs were significantly higher than those in degenerated NPCs(P<0.05).With the normal NPCs+hypoxia group as the control group,the effects of normal or degenerated NPCs,as well as oxygen concentration,on the protein and mRNA expression of PI3K,AKT,and HIF-1α were highly significant.The interaction between cell degeneration and oxygen concentration also had an extremely significant effect on the protein and mRNA expression of PI3K,AKT,and HIF-1α(P<0.001).To conclude,there is a close correlation between the proliferation and apoptosis of NPCs and both oxygen concentration and the cellular functional state.The PI3K/Akt/HIF-1α signaling pathway exhibits antagonistic regulatory effects under various cellular functional states and different oxygen concentration environments.The mechanism may be associated with the activation of the PI3K/Akt signaling pathway,which consequently transcribes HIF-1α,thus maintaining the balance of reactive oxygen species metabolism.This pathway plays a significant role in inhibiting oxidative stress,antagonizing NPCs apoptosis,and consequently delaying intervertebral disc degeneration.

Colorectal cancer (CRC) is one of the most common malignant tumors recorded worldwide. This condition has high morbidity and mortality and seriously endangers people's health. Traditional diagnostic models fail to meet people's current needs for real-time monitoring of tumors. Compared with traditional detection methods, ctDNA detection is not only noninvasive but can also attain real-time detection of comprehensive genomic information of tumors. The advancement of detection technology has gradually highlighted the potential of ctDNA detection in the clinical treatment of CRC. This article reviews the advancements on the clinical application of ctDNA in early screening, minimal residual disease detection, and guidance on individualized treatment of CRC patients.

Objective To investigate the consistency between mismatch repair proyeins expressions detected by immunohistochemistry(IHC)and microsatellite instability(MSI)identified by next-generation sequencing(NGS),and evaluate the correlation of these results with the clinical characteristics of Chinese colorectal cancer(CRC).Methods Using IHC and NGS to identify mismatch repair(MMR)and MSI status in CRC,and assessing the consistency between these different detection methods.Results The concordance rate of MSI status detected by IHC and NGS was 98.36%,indicating good agreement(Kappa=0.856).Certain pathogenic or likely pathogenic germline variants were present in the pMMR/MSI-H subtype.The co-deficiency of MLH1 and PMS2 was most common in the dMMR/MSS subtype.Patients with inconsistent typing were more likely to have early-onset right-sided colon cancer(P<0.01)and the tumor with relatively poor differentiation.Conclusions The consistency of MSI status detected by IHC and NGS is very high,98%or more.To avoid the misdiagnosis of MSI status affecting clinical decision-making for treatment plans,it is imperative to ensure the accuracy of MSI analysis,particularly in poorly differentiated early-stage right-sided colon cancers.

Objective: To explore the clinical effects and key techniques of expanded super-thin perforator flaps in the shoulder, neck, and chest in reconstruction of extensive burn scars in the face. Methods: From January 2008 to November 2018, 22 patients with extensive burn scars in the face were admitted to the Department of Plastic Surgery of Dongguan Kanghua Hospital and the Department of Plastic Surgery of Dermatology Hospital of Southern Medical University, with 3 males and 19 females, aged from 4 to 48 years. There were 16 cases of type Ⅱ and 6 cases of type Ⅲ in facial scars. Before the first stage of expansion surgery, Doppler blood flow survey meter or multi-slice CT was used to locate the perforator vessels. One to four expanders with rated capacity ranged from 100 to 600 mL were placed in the patients. We gave 20% to 30% of the rated capacity of expander intro-operation and common injection with 10% to 15% of the rated capacity of expander per week post-operation until the volume reached 1.5 to 2.5 times of the rated capacity of expander during the past 3 to 4 months. At the second stage of surgery, the perforators were located again before surgery with the same method. The size of defects after the excision of facial scars ranged from 6 cm×4 cm to 18 cm×16 cm. With perforators used as nutrient vessels, narrow pedicle flaps or random flaps ranging from 6 cm×6 cm to 22 cm×18 cm were elevated as rotating or advancing to reconstruct the defects. The donor sites were sutured directly. Some of the flaps needed stage Ⅲ operation for cutting the pedicle. The survival of flaps, post-operation complications, and follow-up were assessed. Results: All flaps of 22 patients survived. All the donor sites were closed simultaneously. One patient underwent an additional surgery for 5 cm×4 cm necrosis on distal part of flap caused by subcutaneous hematoma. Two patients with epidermis blister on the flaps were healed by themselves after dressing change. Due to rapid expansion, blood capillary proliferation appeared on the central part of the flap in 3 cases, after slowing down the expansion speed properly, which had no impact on flap transfer. No ischemia or venous congestion phenomenon were observed in the other flaps. During follow-up of 5 to 48 months, the flaps of patients showed no significant bloated appearance, with good complexion and texture, and even could reproduce facial fine-grained expressions naturally. Conclusions For the reconstruction of extensive burn scars in the face, expanded super-thin perforator flaps can not only acquire large and thin flaps with high matching degree surface skin defect, but also reproduce facial fine-grained expressions. It is a simple and safe method which conforms to the facial aesthetic standard.

Background and purpose:Ca2+plays a very important role in the maintenance of cell biological functions. The storage, release and uptake capacity of Ca2+ is controlled by endoplasmic reticulum (ER). Ca2+ homeo-stasis is essential for cellular energy metabolism and proper protein folding. This study aimed to investigate the effect of cytoplasmic Ca2+ on cisplatin induced ER stress-mediated autophagy in ovarian carcinoma SKOV3 and its underlying mechanism.Methods:The ovarian cancer SKOV3 was used as a study object. The experiment consisted of three parts:① To explore the possible relationship between cisplatin-induced ER stress and autophagy, SKOV3 cells were treated with cisplatin for 0, 6, 12 and 24 h, respectively;② To explore the possible relationship between ER stress induced Ca2+ effux and autophagy, SKOV3 cells were treated with cisplatin for 0, 9 and 12 h, respectively, and TG was used as a positive control;③ To explore the effects of blocking calcium effux on autophagy, SKOV3 cells were divided into control group, cisplatin group, TG group, BAPTA-AM group, cisplatin combined with BAPTA-AM group and TG com-bined with BAPTA-AM group. Western blot was used to detect the protein levels of GRP78 and LC3. Fluo-4 calcium lfuorescent probe was used to examine cytoplasmic Ca2+ levels. Confocal microscopy was used to detect LC3 level by immunolfurescence staining.Results:Compared to control group (0.679±0.011), GRP78 was signiifcantly accumulated at 6, 12 and 24 h after cisplatin treatment and reached the maximum value at 6 h (1.393±0.004,P=0.000). Similarly, compared to control group (0.038±0.000), LC3 puncta were clearly seen after cisplatin treatment and reached the maxi-mum value at 12 h (0.072±0.002,P=0.000). Using confocal microscopy, we found that cisplatin and TG increased LC3 punctate accumulation and cytoplasmic Ca2+ levels in a time-dependent manner. Immunolfuorescent method showed that treatment with cisplatin combined with BAPTA-AM or TG combined with BAPTA-AM increased LC3 punctate accumulation induced by cisplatin or TG. The results of Western blot showed that cisplatin combined with BAPTA-AM (0.071±0.001) or TG combined with BAPTA-AM (0.065±0.001) signiifcantly increased LC3Ⅱ/LC3Ⅰ ratio induced by cisplatin (0.039±0.000,P=0.000) or TG (0.035±0.001,P=0.000).Conclusion:Cisplatin induces intracellular ER stress and autophagy in SKOV3 cells, accompanied by increased cytoplasmic Ca2+ levels. Chelating cytoplasmic Ca2+enhanc-es cisplatin-induced autophagy.

BACKGROUND: It has been explained in many big sample experiments that community comprehensive prevention from the risks of cardiocerebrovascular disease can reduce its morbidity and mortality. But, it is required more samples to verify the evaluations of the process and effect of intervention.OBJECTIVE: To understand the effect of community comprehensive prevention on cardiocerebrovascular disease and hygienic costs demanded and summarizes the suitable patterns of comprehensive prevention on cardiocerebrovascular disease in countryside.DESIGN: Healthy people in community were taken as the objects and community intervention was designed.SETTING: Department of Community Hygienic Service of People's Hospital in Guzheng Town, Zhongshan City, Guangdong Province and Neurological Institute of Guangzhou Medical College.PARTICIPANTS: Totally 32 000 inhabitants were collected from 8 villages in Guzheng Town, Zhongshan City, Guangdong Province from March 1992 to March 2002, aged varied from 20 to 74 years, of which, 14 600inhabitants were male and 17 400 inhabitants were female.METHODS: The intervention of community-based prevention was applied on cardiocerebrovascular disease, including managementof hypertension,smoking control, rational nutrient, nationwide body building and diabetic management.MAIN OUTCOME MEASURES: [1] Awareness, attitude and behavior related to cardiocerebrovascular disease. [2] Management rate and control rate of hypertension. [3] Morbidity and mortality of cerebral apoplexy.RESULTS: [1] By 10-year intervention, awareness rate of hypertension in whole group was 70.29%. [2] Management rate and control rate of hypertension were increased yearly, in which, the management rate was increased from 25.66% in 1997 to 80.50% in 2002, the total control rate was increased from 4.43% in 1997 to 45.80% in 2002, the control rate of blood pressure ＜160/95 mm HG (1 mm Hg=0.133 kPa) was 58.80%and that ＜140/90 mm Hg was 32.80%. [3] The systolic and diastolic pressures in intervention community were decreased averagely, in which the D-values are 7.23 mm Hg and 3.92 mm Hg respectively. [4] The awareness, attitude and behavior related to cardiocerebrovascular disease were enhanced remarkably. [5] Morbidity and mortality of cerebral apoplexy were in tendency of decreasing yearly, from 146.90/100 000 and 108.63/100 000 in 1997 to 105.83/100 000 and 69.90/100 000 in 2002 respectively, by 41.07/100 000 and 38.73/100 000 respectively in 6 years and the age of incidence was postponed. [6] It was indicated in economic analysis that the average ratio of profit to cost between 1997 and 2001 was 2.32.CONCLUSION: Community-based comprehensive prevention on cardiocerebrovascular disease improves the awareness, attitude and behavior in community group and reduces morbidity and mortality of cerebral apoplexy.