An analysis technique of steady state and stability for closed-loop PWM DC/DC switching converters is presented. Using this method, the closed-loop switching converter is transformed into an open-loop system. By means of the fact that in steady state, the two boundary values are equal in one switching period. The exponential matrix is evaluated by precise time-domain-integration method, and then the related curve between feedback duty cycle and the input one is obtained. Not only can the steady-state duty cycle be found from the curve, but also the stability and stable domain of the system. Compared with other methods, it features with simplicity and less calculation, and fit for numerical simulation and analysis for closed-loop switching converters. The simulation results of examples indicate the correctness of the presented method.

Objective To evaluate the association between parameters of heart rate turbulence (HRT) and the severity of the coronary arteries disease. Methods 60 patients with unstable angina pectoris (UAP) who under-went angiographic examination and 40 healthy controls were chosen. HRT including turbulence onset (TO), turbu-lence slope (TS) and turbulence dynamicity (TD) were determined by 24 h ambulatory electrocardiogram(Hoher) in all the patients. The value of above indices were compared between UAP group and control group,and between subgroups of UAP. The correlation of HRT with the severity of coronary arteries diseases was analyzed. Results The levels of TO and TD in patients with UAP were significantly higher than those in controls [(1.18±0.88) % vs lower TS (P<0.05) and higher TD (P<0.05 ) than those in patients with coronary single vessel lesion. The same -0.296, P<0.05 ) and coronary artery stenosis score (r=-0.372, P<0.05 ) ; TD was positively correlated with number of abnormal coronary artery (r=0.353, P<0.01 ) and coronary artery stenosis score (r=0.510, P < 0.05). Conclusion . HRT is impaired in patients with UAP,especially the changes of TS and TD is signflcant,and is correlated with the severity of coronary arteries disease. TD is not influenced by premature ventricualr contractionheart rate so the combinatoin of TD and TS might be used as objective index in predicting the severity of the coronary arteries disease.

Objective To explore the feasibility of mechanical chest compression to establish a rat model of car?diopulmonary resuscitation ( CPR) . Methods 4?month old healthy male Sprague Dawley rats were randomly divided into control group ( n=6 ) and model group ( n=10 ) . After induction of anaesthesia with 10% chloraldurate ( 3 ml/kg, i. p. ) , tracheal intubation and left femoral artery cannulation were performed. Under electrocardiographic and artery blood pressure monitoring, tracheal obstruction ( TO) was performed to rats in model group. At 2 min after the cardiac arrest ( CA) occurred, CPRs were administered to the rats using a self?made animal chest compressor, which provided chest?com?pression at a rate of 200 bpm. Results Shortly after TO, rats in the model group had respiratory arrest, cyanosis and ar?rhythmia. Electrocardiography indicated that CA occurred within 4-5 min, with a decreased artery systolic blood pressure ( <40 mmHg) and a zero pulse pressure. Return of spontaneous circulation ( ROSC) after the CPR was successfully a?chieved in 8 rats (80%), with a transient reperfusion arrhythmia. Finally, 60% of the rats (n=6) recovered to con?sciousness and survived for 24 hrs. The serum biochemical analysis indicated that there were electrolyte disturbances, aci?dosis, impaired renal functions and increased myocardial enzyme spectrum. Pathological examination revealed cardiac rhab? domyolysis, no?reflow phenomenon in renal glomeruli, decrease of neurons and pulmonary congestion in the model group rats. Conclusions Mechanical chest compression can provide minimal cardiac output for the requirement of CPR incardiac arrestin rats. It is feasible to establish rat CPR model with the mechanical chest compression.

BACKGROUND:Recently, the effects of human umbilical cord mesenchymal stem cel s (hUCMSCs) and placenta-derived mesenchymal stem cel s (PDMSCs) on treatment of acute graft versus host disease (aGVHD) have been confirmed in some in vitro studies or animal models. But there are stil no reports comparing the therapeutic effects of these two cel types. OBJECTIVE:To compare the immunosuppressive function of hUCMSCs and PDMSCs in vitro or in a mouse aGVHD model. METHODS:(1) In vitro experiment. Human peripheral blood mononuclear cel s (PBMCs) were isolated and divided into four groups:PBMCs cultured alone, PBMCs stimulated with phytohaemagglutinin (PHA), PHA stimulated-PBMCs cocultured with hUCMSCs, PHA stimulated-PBMCs cocultured with PDMSCs. After 5 days, PBMCs proliferation and interferon-γlevel in cel supernatant were measured. (2) In vivo experiment. Fifty-seven BABL/C(H-2d) mice exposed to 8.5 Gy irradiation were randomly divided into five groups:only saline injection group, syngeneic bone marrow transplantation group, al ogeneic bone marrow transplantation group, aGVHD group, hUCMSCs treatment group, PDMSCs treatment group. The clinical aGVHD score, histopathology of skin, liver, and smal intestine, and survival time were analyzed at days 11, 14, 21 after transplantation. RESULTS AND CONCLUSION:(1) In vitro test:compared with the hUCMSCs, PDMSCs had stronger anti-inflammatory function. (2) In vivo test:The clinical scores on acute graft versus host disease were significantly lower in the hUCMSCs and PDMSCs treatment groups than that in the aGVHD group (P<0.05). The survival rates of mice were significantly increased in the hUCMSCs and PDMSCs treatment groups compared to the aGVHD group (P<0.05). Evident skin lesions were not found in al groups. Although smal intestine mucosal lesions were found in al groups, the damage level seemed similar. Notably, significant difference was found in the liver that multifocal necrosis and a large number of inflammatory cel s were seen in the aGVHD group, but less necrosis and inflammatory cel s in the hUCMSC and PDMSC treatment groups. In conclusion, hUCMSC and PDMSC are comparably effective in the treatment of aGVHD in mice.

Objective To establish a HRM assay to screen for KRAS mutations in clinical colorectal cancer patients.Methods The sensitivity of HRM was analyzed by detecting somatic mutations in exon 2,notably codons 12 and 13 of the KRAS gene in the serial plasmid mixture samples which were mixed using the different proportions mutation plasmid and wide type plasmid of KRAS.HRM analysis was performed for KRAS on DNA insolated from a panel of 60 colorectal cancer samples derived from fresh tissues.The results were compared with the direct sequencing data.Results After the PCR amplification,the mutation results could be available by performing HRM analysis in the same tube on a real time PCR machine with HRM capability.HRM detection could identify KRAS mutation in a proportion of 10% of mutation plasmid DNA.All 60 samples identified the KRAS mutation by HRM and sequencing.17 samples were positive(28.3%) by HRM for KRAS exon 2 mutations,and 15 samples were confirmed the presence of codon 12 or 13 mutations(25.0%) and the other 2 samples were wild type by sequencing.The 60 samples detected by HRM were given 100% sensitivity with 96% specificity.Conclusions HRM is a sensitive intube methodology to screen for mutations in clinical samples.HRM will enable high-throughput screening to gene mutations to allow appropriate therapeutic choices for patients and accelerate research aimed at identifying novel mutations in human cancer.

Von Hippel-Lindau (VHL) disease is a benign or malignant tumor syndrome which involves multiple systems and organs.Recently,a patient was diagnosed and hospitalized with an initial clinical symptom of pancreatic multiple cystic space-occupying.Multidisciplinary examination and consultation confirmed that there were hemangioblastomas in cerebella,spinal cord and retina,but with no clinical symptoms;therefore,it was diagnosed as VHL disease.According to previous case reports,only a few single cases revealed lesions in so many parts of the central nervous system with typical imaging manifestations.We present an overview and aim to improve the diagnosis of VHL disease with the initial clinical symptom of pancreatic lesions.

Objective:To investigate the effect of cholesterol-modified prognostic nutritional index (cPNI) on postoperative long-term prognosis of the borderline resectable pancreatic cancer (BRPC).Methods:Clinical data of 173 patients with BRPC admitted to the Department of Hepatobiliary and Pancreaticosplenic Surgery, Beijing Chaoyang Hospital, Capital Medical University from January 2011 to September 2023 were retrospectively analyzed, including 90 males and 83 females, aged (61.7±9.8) years. The receiver operating curve (ROC) of preoperative cPNI predicting 1-year postoperative survival was drawn and the optimal cut-off value in predicting 1-year survival was 77.36. Patients were divided into low cPNI ( n=83, cPNI≤77.36) and high cPNI group ( n=90, cPNI>77.36). Kaplan-Meier method was used for survival analysis, log-rank test was used for univariate analysis, and Cox proportion hazard model was used for multivariate analysis to reveal the effect of cPNI on postoperative long-term survival in patients with BRPC. Results:The cumulative survival rates at 1, 2 and 3 years after surgery in low cPNI group and high cPNI group were 70.6%, 40.3%, 21.8%, and 48.3%, 21.5%, 9.5%, respectively ( χ2=8.49, P=0.004). Univariate analysis showed that preoperative cPNI, length of portal vein invasion, tumor differentiation degree, tumor TNM stage, tumor diameter, lymph node metastasis, and postoperative chemotherapy were correlated with long-term survival of BRPC patients (all P<0.05). Multivariate analysis showed that BRPC patients with preoperative cPNI >77.36 ( HR=1.452, 95% CI: 1.026-2.053, P=0.035) had a increased risk of postoperative death, while patients with length of portal venous invasion >3.0 cm, poorer tumor differentiation, lymph node metastasis and no postoperative chemotherapy had an increased risk of postoperative death. Conclusion:Preoperative cPNI >77.36 is a risk factor for long-term survival in BRPC patients.

Ganoderic triterpenoids (GTs) are the primary bioactive constituents of the Basidiomycotina fungus,

Objective:To evaluate the predictive value of prognostic nutritional index (PNI) for survival after radical resection in patients with distal cholangiocarcinoma.Methods:The clinical data of 160 patients with distal cholangiocarcinoma undergoing radical pancreatoduodenectomy in Beijing Chaoyang Hospital Affiliated to Capital Medical University from September 2011 to March 2022 were retrospectively analyzed, including 97 males and 63 females, aged (65.58±9.22) years old. The optimal cut-off value of PNI for predicting postoperative survival was 42.275 determined by the receiver operating characteristic curve. Patients were divided into the low PNI group ( n=79, PNI<42.275) and high PNI group ( n=81, PNI≥42.275). The survival status of patients were followed up by outpatient clinic or telephone review. Survival analysis was performed using the Kaplan-Meier method and the log-rank test. Factors with P<0.1 in the univariate analysis were included in the Cox proportional hazards model for multivariate analysis to screen the prognostic factors. Results:There were statistically significant differences in the preoperative albumin, total bilirubin, lymphocytes counts between the two group (all P<0.05). The postoperative median survival time of the low PNI group was 17 months, with cumulative 1, 3 and 5-year survival rates of 62.0%, 25.0% and 16.2%, respectively. The postoperative median survival time of the high PNI group was 23 months, with cumulative 1, 3 and 5-year survival rates of 84.0%, 46.4% and 40.4%, respectively. There was a significant difference between the two groups ( P<0.001). PNI score<42.275 ( HR=1.040, 95% CI: 1.011-1.071, P=0.008), CA19-9>37 U/ml ( HR=1.620, 95% CI: 1.046-2.509, P=0.031), venous invasion ( HR=1.809, 95% CI: 1.013-3.230, P=0.045), lymph node metastasis ( HR=1.956, 95% CI: 1.300-2.969, P=0.001), tumor diameter >2 cm ( HR=1.534, 95% CI: 1.011-2.328, P=0.044), without postoperative adjuvant chemotherapy ( HR=2.828, 95% CI: 1.291-6.195, P=0.009) had a greater risk of poor survival after radical resection. Conclusion:PNI score could be an influencing factor and serve as a predicting tool for the survival after radical resection in patients with distal cholangiocarci-noma.

Objective:To analyse the differences of related genes between serum alpha-fetoprotein (AFP) positive gastric cancer and AFP negative gastric cancer, and the relationship between related genes and prognosis of serum AFP positive gastric cancer.Methods:A total of 1 144 gastric cancer patients undergoing surgery at the 940th Hospital , Joint Logistic Support Force, People's Liberation Army from Jan 2013 to Dec 2018 were retrospectively analyzed. Of them, 47 cases were of AFP positive gastric cancer, and 47 serum AFP negative case were obtained by proper matching method.Results:Forty-seven patients with serum AFP positive gastric cancer, accounting for 4.1% of all gastric cancer patients during the same period. The prognosis of serum AFP negative gastric cancer is better than that of serum AFP positive gastric cancer. The 1-, 3- and 5-year cumulative survival rates were 95.6% vs. 63.8%, 48.9% vs. 23.4% and 26.7% vs. 14.9%, respectively. There were statistical differences in the immunohistochemistry of AFP, HER2, VEGF, GPC3, SALL4, P53 and Ki67 between the two groups ( χ2=67.758, P<0.001; χ2=4.004, P=0.044; χ2=19.299, P<0.001; χ2=5.232, P=0.022; χ2=6.359, P=0.012; χ2=6.224, P=0.013; χ2=5.232, P=0.022). The more co-positive expressions of AFP, GPC3, VEGF and SALL4, the more likely they were to affect pTNM stage, vascular invasion and liver metastasis ( χ2=5.328, P=0.021; P=0.013; χ2=5.887, P=0.015; χ2=3.923, P=0.048). Univariate and multivariate survival analysis of serum AFP positive gastric cancer showed:AFP, GPC3, VEGF and SALL4 were risk factors for AFP positive gastric cancer ( HR=3.700, P=0.036; HR=4.237, P=0.003; HR=3.916, P=0.004; HR=3.412, P=0.001). Conclusions:Serum AFP positive gastric cancer is a rare and highly invasive special type of gastric cancer. AFP, GPC3, VEGF and SALL4 are overexpressed in serum AFP positive gastric cancer, which is correlated with tumor stage, vascular invasion and liver metastasis. The final diagnosis of serum AFP positive gastric cancer still needs immunohistochemical examination. Preoperative serum AFP level is an important basis for AFP positive gastric cancer screening and AFP immunohistochemical examination.