SVC装置阀组检测电路的研究

结合实际应用电路,分析晶闸管可能发生的故障,进而研究两种不同的检测电路,并结合图表阐述其原理。     

von Hippel-Lindau gene mutations in N-nitrosodimethylamine-induced rat renal epithelial tumors

BACKGROUND: Mutations in the von Hippel-Lindau (VHL) gene are common in human clear cell kidney cancers. Carcinogens in cigarette smoke, especially nitrosamines, are known to induce kidney tumors of a variety of histologic types in rodents--but with no evidence of VHL mutations; however, none of these tumors resembled human clear cell carcinomas. We examined N-nitrosodimethylamine-induced kidney tumors of the clear or mixed clear/granular cell type in Wistar rats to assess the presence of VHL mutations. METHODS: Sections of eight clear or mixed clear/granular cell kidney tumors that had been formalin fixed and paraffin embedded were microdissected. DNA was extracted from the microdissected tissue, and exons 1-3 of the rat VHL gene were examined by use of polymerase chain reaction and cycle sequencing techniques. RESULTS: Four VHL gene mutations (three G:C to A:T and one A:T to G:C) were detected in three of the tumors in contrast to no mutations in 40 previously reported rat kidney tumors of other histologic types (three of eight tumors versus none of 40; two-sided Fisher's exact test; P=.003). Only tumors showing prominent swollen clear cell cytology with a signet-ring appearance had VHL mutations. CONCLUSIONS: To our knowledge, this is the first report of VHL mutations in kidney tumors after direct chemical exposure and provides a possible molecular pathway linking tobacco smoking to kidney cancer.     

Experiences with the Soviet suture stapler SPTU in colon and and rectum surgery. Controlled study of 94 patients

In a controlled study the practicability, tightness of the anastomosis and complications in the p.o. period were analyzed in a total 94 colon and rectum anastomoses by making use of the SPTU-model. 28% of the patients operated in this way were more than 70 years old, the average age came up to 63.3 years. The incidence of anastomotic leakage after low anterior resection was 24% and 5.5% after high anterior resection. 17 per cent of the patients suffered from complications during the postoperative period and 2 patients (2.1 per cent) came to death. The results of 36 high and 58 low anterior resections justify the further use of the SPTU auto-suture apparatus.     

Aggregation fo blood platelets and increased hydraulic conductivity of pulmonary exchange vessels

Pulmonary microembolization secondary to platelet aggregation has been suggested to be a pathogenetic component of the shock lung syndrome. In vitro experiments have also shown that platelets can release factors with a permeability-enhancing activity. We studied the effect of collagen-induced platelet aggregation on the hydraulic conductivity of thexchange vessels in isolated, blood-perfused rabbit lungs. The net rate of fluid filtration in each pair of lungs was determined during standardized elevations of left atrial pressure before and after platelet aggregation induced by intraarterial collagen infusions. Such infusions were followed by a significant, but transient increase in the net rate of fluid filtration. These lungs were papaverinized so that collagen infusions caused only minor increases in inflow pressure. Separate experiments indicated that the observed increase in pulmonary arterial pressure could not explain the increase in net filtration rate after collagen infusion. When platelet-poor plasma was used as a perfusate no change in the net rate of fluid filtration was observed after collagen infusion. The conclusion from these experiments is then that intravascular platelet aggregation induced by collagen infusion caused a transient increase in the permeability of the pulmonary exchange vessels.     

Hodgkin's disease in children: clinico-roentgenologic features of the lesion in the chest

The roentgenologic features of Hodgkin's disease were studied in 105 patients under 14 years of age. The mediastinal and hilar nodes were involved in 64.7% of patients. Some consistency of extent and pattern of disease was observed in that mediastinal lymphatic lesions could be associated with cervico-supra-clavicular and retroperitoneal lesions. There was lung infiltration in 14.3% of patients and the frequency of this lesion dependent on the histological type. It was commoner in nodular sclerosis, mixed cellularity and lymphocytic depletion. Lung infiltration usually developed in continuity with the lymphatic gland lesion and only rarely in a metastasis-like form.