惠来地区蔬菜土壤中Pb和As的形态分析

采用七步提取法对惠来蔬菜土壤中的重金属Pb和As进行形态分析,并研究了Pb和As的生物可给性,结果表明Pb和As的分布以残渣态为主,Pb的生物可利用态含量较少,当环境改变时,As的生物可给性可能存在潜在的危害。     

Blood pressure changes during short-term fluoxetine treatment

PURPOSE: To evaluate the potential diagnostic role of mediastinal sonography in patients with cystic fibrosis (CF), we screened the mediastinum of adult CF patients with and without signs of infection and healthy controls. METHODS: Fifty-four consecutive adult patients with CF and 53 healthy volunteers underwent high-resolution mediastinal sonography. The paratracheal region and aorticopulmonary window of each subject were examined for lymph nodes. Each patient was screened for clinical signs of infection. RESULTS: Lymph nodes were detectable in the mediastinum of 39 of 50 CF patients (78%); the mean total lymph node volume was 1.5 +/- 1.7 cm3. Lymph nodes were detectable in the mediastinum of 31 of 50 controls (62%); the mean total lymph node volume in this group was 0.3 +/- 0.3 cm3 (p < 0.001). In the 30 CF patients with signs of infection, the mean total lymph node volume was larger (2.0 +/- 1.8 cm3) than in the 20 CF patients without signs of infection (0.7 +/- 0.9 cm3; p = 0.002). CONCLUSIONS: These results indicate that lymph node volume determination by high-resolution mediastinal sonography may help assess inflammatory activity in patients with CF.     

The mechanisms of cracks formation of silver-based contact materials under arc and making pressure

The arc erosion experiments on five kinds of silver-based contact materials,AgZnO (10), AgSnO2 (8.5) In2O3 (4), AgCdO (12), AgNi(10), AgWC(12)C(3) were carried out according to different breaking times, breaking currents, and making pressures. Then based on the theoretical analysis and the photographs taken by scanning electronic microscope with EDAX analyzer, the crack morphology was studied scientifically. Three types of cracks, which are cavity cracks, grain boundaries (or phase boundaries) slipping cracks, and thermal stress cracks, were put forward under arc and making pressure through establishing their physical models and discussing their formation mechanisms.     

Bypass surgery for vascular disease of the carotid system

A series of 58 operations on 56 patients, in whom a branch of the superficial temporal artery was anastomosed to a branch of the middle cerebral artery (STA-MCA bypass or Yasargil procedure), is reviewed. These operations were performed chiefly for occlussions or for inaccessible stenotic lesions of the internal carotid or middle cerebral arteries. Patency in eight patients operated on from April 1971 through November 1973 was low (25%). Patency in patients operated on since July 1974 has been high (95%). There have been no deaths and no major ischemic strokes attributable to the surgery. The rationale for this procedure is considered in relationship to the anatomy and physiology of the cerebral circulation and the pathogenesis of syndromes of cerebral ischemia. The operation appears to have a low morbidity in good-risk patients. The role of this operation in managing common manifestations of cerebral vascular disease such as focal transient cerebral ischemic attacks (TIAs) and amaurosis fugax, although not fully established, appears encouraging. The procedure seems useful for orthostatic cerebral ischemia caused by multiple occlusions of major extracranial (and intracranial) vessels and, occasionally, for progressing strokes related to internal carotid artery occlusion, both of which are relatively uncommon manifestations of cerebral vascular occlusive disease. It may have application in the rare "slow stroke." The procedure is probably of limited value, if any, in the management of large completed infarcts but may be indicated in selected patients with small infarctions who have preserved most of their cerebral function and who have had evidence of subsequent focal ischemic events. The procedure is useful for bypassing giant aneurysms or basofrontal tumors invading major vessels. It may have a role in the management of fibromuscular disease of the internal carotid artery.     

Neocuproine, a selective Cu(I) chelator, and the relaxation of rat vascular smooth muscle by S-nitrosothiols

1. A study has been made of the effect of neocuproine, a specific Cu(I) chelator, on vasodilator responses of rat isolated perfused tail artery to two nitrosothiols: S-nitroso-N-acetyl-D,L-penicillamine (SNAP) and S-nitroso-glutathione (GSNO). 2. Bolus injections (10 microl) of SNAP or GSNO (10(-7)-10(-3) M) were delivered into the lumen of perfused vessels pre-contracted with sufficient phenylephrine (1-7 microM) to develop pressures of 100-120 mmHg. Two kinds of experiment were made: SNAP and GSNO were either (a) pre-mixed with neocuproine (10(-4) M) and then injected into arteries; or (b) vessels were continuously perfused with neocuproine (10(-5) M) and then injected with either pure SNAP or GSNO. 3. In each case, neocuproine significantly attenuated vasodilator responses to both nitrosothiols, although the nature of the inhibitory effect differed in the two types of experiment. We conclude that the ability of exogenous nitrosothiols to relax vascular smooth muscle in our ex vivo model is dependent upon a Cu(I) catalyzed process. Evidence is presented which suggests that a similar Cu(I)-dependent mechanism is responsible for the release of NO from endogenous nitrosothiols and that this process may assist in maintaining vasodilator tone in vivo.