Peptide‒drug conjugates (PDCs) are drug delivery systems consisting of a drug covalently coupled to a multifunctional peptide via a cleavable linker. As an emerging prodrug strategy, PDCs not only preserve the function and bioactivity of the peptides but also release the drugs responsively with the cleavable property of the linkers. Given the ability to significantly improve the circulation stability and targeting of drugs in vivo and reduce the toxic side effects of drugs, PDCs have already been extensively applied in drug delivery. Herein, we review the types and mechanisms of peptides, linkers and drugs used to construct PDCs, and summarize the clinical applications and challenges of PDC drugs.

Objective:To evaluate the effect of proprotein convertase subtilisin/kexin type 9 (PCSK9) on lipid homeostasis and cellular injury of podocytes, and to clarify its mechanism.Methods:Twelve-week old C57BL/6 wild-type mice ( n=10) and PCSK9 knockout ( PCSK9 KO) mice ( n=10) were selected as the animal models. The renal tissues were taken after perfusion through heart. Mouse podocytes were transfected with PCSK9 siRNA to downregulate PCSK9 expression. BODIPY 493/503 staining was performed for evaluating lipid accumulation, and standard transmission electron microscopy (TEM) was used to observe the foot process of podocytes, the shape of mitochondria and lipid droplet in podocytes. TUNEL staining was carried out to evaluate cell apoptosis in glomerulus. The parameters about mitochondria function (key enzymes such as PGC-1α, CPT-1 and Acox-1) and apoptosis were quantified through qPCR and western blotting. Results:The lipid accumulation in glomerulus of PCSK9 KO mice were more serious than controls. The expression of PGC-1α protein and PGC-1α, CPT-1 and Acox-1 mRNA in PCSK9 KO mouse kidney tissues were decreased than controls (all P<0.05), and mitochondria swelling and cristae disappearance in podocytes of PCSK9 KO mice were observed. In PCSK9 KO group, the foot process of podocytes partially fused and disappeared, and the apoptosis index increased compared with the control group ( P<0.05). In vitro, compared with the control group, the lipid accumulation was more significant, transcription level of key enzymes related to mitochondrial function was decreased, mitochondrial structure was damaged and the apoptosis index was increased in cultured podocyte PCSK9 siRNA group (all P<0.05). Conclusions:PCSK9 is involved in the lipid homeostasis of podocytes. The decrease of PCSK9 results in the increase of intracellular lipid accumulation, accompanied by the mitochondrial structure damage and disfunction of podocytes, and leads to cell apoptosis.

Objective: To understand the situation and genotype distribution of spotted fever group rickettsia (SFGR) in the border area of Tumen River Basin in free ticks in Yanbian Korean Autonomous Prefecture (Yanbian Prefecture), Jilin Province. Methods: From April to September, 2017, ticks were collected using flagging method from Hunchun, Tumen, Helong and Longjing cities in the Tumen River basin of Yanbian Prefecture. Outer membrane protein A (ompA) was detected by Polymerase Chain Reaction (PCR), then, the species were identified by gene sequencing and analyzed systematically. The positive rate of pools and MIR(minimum infection rate per 100 ticks,MIR) of SFGR were calculated, and the difference of positive rate of pools among ticks with different characteristics was compared by Chi-square test. Results: A total of 3 079 ticks were collected and divided into 536 pools. The positive rate of pools of SFGR nucleic acid was 39.7% (213 pools). The MIR of SFGR was 6.9%.The positive rate of pools of SFGR in Dermacentor silvarum, Haemaphysalis concinna, Haemaphysalis japonica, Haemaphysalis longicornis and Ixodes persulcatus were 80.4% (41/51), 14.0% (25/179), 20.2% (18/89), 78.9% (101/128) and 25.9% (21/81), and the difference was statistically significant (P<0.001). There was statistical difference in the positive rate of pools of SFGR in developmental stages of ticks (P<0.001); the positive rate of pools of female adults, male adults, nymph and larvae were 36.4% (95/261), 34.2% (67/196), 56.3% (40/71) and 7/8, and the MIR was 7.9%, 7.7%, 4.9% and 3.5%. The five genotype was detected which was Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis, Candidatus Rickettsia tarasevichiae,Rickettsia monacensis and have 98%-100% homology with known gene sequences. Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis and Candidatus Rickettsia tarasevichiae showed close evolutionary relationship with known specie (have 98%-100% homology with known gene sequences); Rickettsia monacensis showed Far from evolutionary relationship with known species (have 98% homology with known gene sequences). Conclusion SFGR infection of ticks is common in the border areas of the Tumen River Basin. There was high diversity in SFGR species and tick species in the areas surveyed.

Objective To understand the situation and genotype distribution of spotted fever group rickettsia (SFGR) in the border area of Tumen River Basin in free ticks in Yanbian Korean Autonomous Prefecture (Yanbian Prefecture), Jilin Province. Methods From April to September, 2017, ticks were collected using flagging method from Hunchun, Tumen, Helong and Longjing cities in the Tumen River basin of Yanbian Prefecture. Outer membrane protein A (ompA) was detected by Polymerase Chain Reaction (PCR), then, the species were identified by gene sequencing and analyzed systematically. The positive rate of pools and MIR(minimum infection rate per 100 ticks,MIR) of SFGR were calculated, and the difference of positive rate of pools among ticks with different characteristics was compared by Chi?square test. Results A total of 3 079 ticks were collected and divided into 536 pools. The positive rate of pools of SFGR nucleic acid was 39.7% (213 pools). The MIR of SFGR was 6.9%.The positive rate of pools of SFGR in Dermacentor silvarum, Haemaphysalis concinna, Haemaphysalis japonica, Haemaphysalis longicornis and Ixodes persulcatus were 80.4% (41/51), 14.0% (25/179), 20.2% (18/89), 78.9% (101/128) and 25.9% (21/81), and the difference was statistically significant (P<0.001). There was statistical difference in the positive rate of pools of SFGR in developmental stages of ticks (P<0.001); the positive rate of pools of female adults, male adults, nymph and larvae were 36.4% (95/261), 34.2% (67/196), 56.3% (40/71) and 7/8, and the MIR was 7.9%, 7.7%, 4.9% and 3.5%. The five genotype was detected which was Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis, Candidatus Rickettsia tarasevichiae,Rickettsia monacensis and have 98%-100% homology with known gene sequences. Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis and Candidatus Rickettsia tarasevichiae showed close evolutionary relationship with known specie (have 98%-100% homology with known gene sequences); Rickettsia monacensis showed Far from evolutionary relationship with known species (have 98% homology with known gene sequences). Conclusion SFGR infection of ticks is common in the border areas of the Tumen River Basin. There was high diversity in SFGR species and tick species in the areas surveyed.

Objective To understand the situation and genotype distribution of spotted fever group rickettsia (SFGR) in the border area of Tumen River Basin in free ticks in Yanbian Korean Autonomous Prefecture (Yanbian Prefecture), Jilin Province. Methods From April to September, 2017, ticks were collected using flagging method from Hunchun, Tumen, Helong and Longjing cities in the Tumen River basin of Yanbian Prefecture. Outer membrane protein A (ompA) was detected by Polymerase Chain Reaction (PCR), then, the species were identified by gene sequencing and analyzed systematically. The positive rate of pools and MIR(minimum infection rate per 100 ticks,MIR) of SFGR were calculated, and the difference of positive rate of pools among ticks with different characteristics was compared by Chi?square test. Results A total of 3 079 ticks were collected and divided into 536 pools. The positive rate of pools of SFGR nucleic acid was 39.7% (213 pools). The MIR of SFGR was 6.9%.The positive rate of pools of SFGR in Dermacentor silvarum, Haemaphysalis concinna, Haemaphysalis japonica, Haemaphysalis longicornis and Ixodes persulcatus were 80.4% (41/51), 14.0% (25/179), 20.2% (18/89), 78.9% (101/128) and 25.9% (21/81), and the difference was statistically significant (P<0.001). There was statistical difference in the positive rate of pools of SFGR in developmental stages of ticks (P<0.001); the positive rate of pools of female adults, male adults, nymph and larvae were 36.4% (95/261), 34.2% (67/196), 56.3% (40/71) and 7/8, and the MIR was 7.9%, 7.7%, 4.9% and 3.5%. The five genotype was detected which was Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis, Candidatus Rickettsia tarasevichiae,Rickettsia monacensis and have 98%-100% homology with known gene sequences. Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis and Candidatus Rickettsia tarasevichiae showed close evolutionary relationship with known specie (have 98%-100% homology with known gene sequences); Rickettsia monacensis showed Far from evolutionary relationship with known species (have 98% homology with known gene sequences). Conclusion SFGR infection of ticks is common in the border areas of the Tumen River Basin. There was high diversity in SFGR species and tick species in the areas surveyed.

Objectives To evaluate the role of PCSK9 (proprotein convertase subtilisin kexin type 9) on the lipid accumulation and kidney injury of C57BL/6 mice. Methods The 24 h urine of 12 weeks old wide type C57BL/6 mice and PCSK9 knockout (KO) mice were collected through a metabolic cage, followed by perfusion and sacrifice. Urinary microalbumin?to?creatinine ratio (UACr), total cholesterol and triglyceride in kidney tissues were measured by ELISA. BODIPY 493/503 staining and standard transmission electron microscopy (TEM) of kidney tissues was performed for evaluating lipid accumulation and podocyte foot effacement in the kidney. Kidney tissues were also evaluated by PAS stain and TUNNEL stain. PCSK9, podocin and nephrin were quantified through real?time PCR, and the Bcl?2, Bax and cleaved caspase 3 were evaluated by Western blotting. Results Total cholesterol and triglyceride contents were higher in the kidneys of PCSK9 KO mice than controls (P<0.05). The level of lipid accumulation in glomeruli and tubules through BODIPY 493/503 stain, and the amount of lipid drop in TEM were more serious in PCSK9 KO mice. UACr and podocyte foot process effacement were increased, and the transcription of podocin and nephrin were decreased in the kidneys of PCSK9 KO mice (all P<0.05). The expression of Bcl?2 was decreased, and Bax and cleavedcaspase 3 were increased in the kidney samples of PCSK9 KO mice. Conclusion PCSK9 might be reversely involved in lipid homeostasis and accumulation, resulting in injury and apoptosis in the kidneys of C57BL/6 mice.

Objective To evaluate the diagnostic value of MSCT in the differentiation of thymic epithelial tumours (TET)with the maximum diameter equal or less than 3 cm.Methods A retrospective analysis of pathological and imaging data of 56 patients with pathologically confirmed TET with the maximum diameter equal or less than 3 cm was performed.According to the 2004 WHO classification,56 TETs were classified as low-risk thymomas(types A/AB/B1),high-risk thymomas (types B2/B3)and thymic carcinomas (type C).The CT manifestations of TET in each group,including shape of tumor,tumor edge (smooth or spiculate protuberance), presence of small nodule around tumor,enhancement degree,pleura invasion and fat space around tumor,were analyzed retrospectively.The differences in the CT manifestations among three types were compared using chi-square test.If the sample number was too small, Fisher 's exact test was used.Results Compared with high-risk thymomas (23 cases)and thymic carcinomas (6 cases),regular round shape was more often observed in low-risk thymomas (27 cases)(χ2 =73,P <0.001;χ2 =116,P <0.001)and the mediastinum-lung interface was more likely to bulge (χ2 = 3.41,P =0.046;χ2 =7.39,P =0.01).Blurred edge,spiculate protuberance and pleural invasion and so on were significantly more common in high-risk thymomas and thymic carcinomas (P <0.001)and they were the most common in thymic carcinomas (χ2 =11.5,P =0.009).There was a significant difference between type B2 thymomas and thymic carcinomas (χ2 =31.52, P <0.001),however there was no significant difference between type B3 thymomas and thymic carcinomas (χ2 =6.96,P =0.07). Conclusion MSCT can accurately show the shape of tumor,tumor edge,presence of small nodule around tumor,enhancement degree,pleura invasion,which can predict the histologic type of thymomas and also can provide information for preoperative diagnosis and prognosis evaluation.

Objective To explore the clinical effectiveness and safety of selective usage of embolic protection device to prevent distal embolization during SilverHawk atherectomy for atherosclerotic femoropo-pliteal artery disease. Methods From Jan 2014 to December 2015, 45 femoropopliteal artery atherosclerot-ic patients were treated with SilverHawk atherectomy and selective embolic protection device (EPD). The indication for EPD was instent restenosis, highly calcified lesion, suspicious of thrombosis, ulcerated le-sion, and single below-the-knee runoff. All cases who met the indication were treated with atherectomy and EPD, and those who did not meet the indication were treated with or without EPD according to the patient's choice. The embolic related complications were analyzed. Results Twenty three out of 45 patients who met the EPD indication were all treated with SilverHawk atherectomy under EPD protection, filter captured deb-ris in 17 patients (73. 9％) of the patients. The other 22 patients who did not meet the indication were di-vided into 2 groups according to the patient's choice of EPD usage, 11 were treated by atherectomy with EPD and 11 without EPD. One case out of 11 unindicated patients without EPD suffered a tibioperoneal trunk embolization and restored with catheter aspiration. For 1/11 (9. 1％) unindicated cases with EPD protec-tion, the filter captured embolization. There was a significant difference of distal embolization rate between the indicated and unindicated patients (χ2 =19. 368,P =0. 000). All filters were retrieved successfully without any distal embolization and any complications except arterial spasm occurred in 2 patients and re-stored well with nitroglycerin. Conclusions It is safe and effective for selective usage of embolic protection device to prevent distal embolization during SilverHawk atherectomy for atherosclerotic femoropopliteal artery disease.

This study aims to determine whether successful laparoscopic fundoplication for gastroesophageal reflux disease (GERD) can improve the control of hypertension.We conducted an observational study of GERD patients with hypertension.The esophageal and gastroesophageal symptoms of these patients were successfully treated with laparoscopic fundoplication,as measured by the reduced GERD symptoms and proton pump inhibitor consumption.A hypertension control scale was used to classify the use of antihypertensive medications and the quality of blood pressure control before and after anti-reflux surgery.Wilcoxon signed-ranks test was used for the statistical analyses.Seventy GERD patients were included in the analysis and followed up for a mean period of 3.5 ± 1.4 years.Prior to surgery,all participating patients were taking at least one class of antihypertensive medication,and 56 patients (80％) had intermittently high blood pressure.After surgery,the mean number of antihypertensive medication classes per patient was significantly reduced from 1.61 ± 0.77 pre-procedure to 1.27 ± 0.88 post-procedure (P ＜ 0.001).The blood pressure of 48 of the 56 cases (86％) with preoperative intermittent high blood pressure returned to normal post procedure.A total of 50 patients (71％) recorded improvements on the hypertension control scale,with the overall mean score decreasing from 3.1 ± 1.0 preprocedure to 1.4 ± 1.0 post-procedure (P ＜ 0.001).Therefore,successful laparoscopic fundoplication may result in better blood pressure control in some hypertensive GERD patients.This result suggests a possible connection between gastroesophageal reflux and hypertension.

Objective To evaluate the effectiveness and complications of laparoscopic repair for hiatal hernia.Methods The clinical data of 992 patients with hiatal hernia undergoing laparoscopic repair from Jan 2008 to June 2014 were collected and analyzed.Postoperative symptom scores,postoperative complications,recurrence rate and satisfaction were evaluated.Results 858 cases were followed up,including type Ⅰ HH accounting for 79.8％,type Ⅱ for 1.3％,type Ⅲ for 17.1％,type Ⅳ for 1.8％ respectively.HH repaired with mesh in 520 cases.The overall improvement rate was 96.2％.Postoperative symptom scores significantly decreased.Recurrence of anatomy and symptoms were 31 and 15 cases respectively.Short-term and long-term of postoperative complications were 35.8％ and 5.6％ respectively.Excellent,fair and poor result were achieved in 91.8％,4.3％,3.9％ of postoperatively follow-up cases,respectively.Conclusion The laparoscopic approach for repair of hiatal hernias is of minimally invasive,lower recurrence rate,less complications and high satisfaction.