大狼毒三萜类化学成分的研究

自大戟科(Euphorbiaceae)植物大狼毒(Euphorbia nematocypha Hand—Mazz)根的乙醇提取物的苯溶解部分,经20%AgNO₃硅胶层析,分离得到七个三萜类成分。根据光谱(IR,EIMS,¹H—NMR和¹³C—NMR)和化学方法,确定其中一个化合物为新化合物,命名为大狼毒醇(nematocyphol,Ⅳa),其它化合物为已知物:印度荆芥醇乙酸酯(nepehinol acetate Ⅰ),日尔曼醇乙酸酯(germanicol acetate Ⅱ),大戟醇(euphol,Ⅲ),蒲公英醇(taraxasterol,Ⅴa),24-亚甲基环阿尔廷醇(24-methylenecycloartanol,Ⅴa)和印度荆芥醇(nepehinol,Ⅶa)。这些化合物均为首次从大狼毒中得到。     

Small interfering RNA inhibits SARS-CoV nucleocapsid gene expression in cultured cells and mouse muscles

SARS-CoV isa newly identified coronavirus that causes severe acute respiratory syndrome （SARS）. Currently, there is no effective method available for prophylaxis and treatment of SARS-CoVinfections. In the present study, the influence of small interfering RNA （siRNA） on SARS-CoV nucleocapsid （N） protein expression was detected in cultured cells and mouse muscles. Four siRNA expression cassettes driven by mouse U6 promoter targeting SARS-CoV N gene were prepared, and their inhibitory effects on expression of N and enhanced green fluorescence protein （EGFP） fusion protein were observed.     

Duplex ultrasonography of the portal vein

Although the ability of ultrasonography to provide anatomic detail and physiologic information about the arterial system is well established, its applicability for the venous system and the splanchnic circulation has only recently been recognized. We have found duplex scanning, which is non-invasive, rapid, inexpensive, and reproducible, to be highly accurate in (1) establishing or confirming the diagnosis of portal hypertension, (2) demonstrating portal and splenic vein patency and direction of flow, (3) assessing portosystemic shunt patency, and (4) providing novel anatomic and physiologic information regarding the normal and diseased splanchnic venous system. These ultrasonographic techniques also have a significant role to play in the surveillance of patients who have undergone liver transplantation or massive liver resection. To a great extent, ultrasonography may supplant the invasiveness, discomfort, and expense of contrast angiography in the evaluation of many patients with advanced liver disease.     

Low-artifact intravascular devices: MR imaging evaluation

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.     

Loss of somatal neuropeptide y immunoreactivity in the rat hippocampus following transient cerebral ischemia

Adult male Wistar rats were subjected to 20 min of global cerebral ischemia and allowed to survive for 1, 2, 4, or 21 days. The brains were processed for immunocytochemistry and the hippocampal neuropeptide Y (NPY)-immunoreactive (-i) neurons were counted and compared to control values. In order to map out the subregional distribution of ischemic cell loss in the hippocampus, cells were also counted in hematoxylin-eosin (HE)-stained brain sections processed from additional ischemic rats after 21 days survival. Cell counts demonstrated a significant loss of hippocampal NPY-i somata 1-21 days after ischemia. The ischemic loss of somatal NPY-i was in the CAI stratum oriens, the CA1 stratum radiatum, and the CA3(ab) subfield not correlated to hippocampal cell loss. NPY-i fibers were found in all subfields of the hippocampus 1-21 days after ischemia. It is known that the majority (>50%) of hippocampal somatostatin-i (SS) neurons also costore NPY-i and the SS-i neurons in the CA1 and CA3(ab) regions of the hippocampus are preserved following an ischemic insult. The present results showed a 90% ischemic loss of CA1 and CA3 NPY-i somata. Based on these findings, it is concluded that ischemia selectively damaged NPY-i and not SS-i within some surviving hippocampal neurons that co-localized both peptides prior to the ischemia.     

Novel mouse model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis

Pseudomonas aeruginosa causes a chronic infection in the lungs of cystic fibrosis (CF) patients by establishing an alginate-containing biofilm. The infection has been studied in several animal models; however, most of the models required artificial embedding of the bacteria. We present here a new pulmonary mouse model without artificial embedding. The model is based on a stable mucoid CF sputum isolate (NH57388A) with hyperproduction of alginate due to a deletion in mucA and functional N-acylhomoserine lactone (AHL)-based quorum-sensing systems. Chronic lung infection could be established in both CF mice (Cftr(tmlUnc-/-)) and BALB/c mice, as reflected by the detection of a high number of P. aeruginosa organisms in the lung homogenates at 7 days postinfection and alginate biofilms, surrounded by polymorphonuclear leukocytes in the alveoli. In comparison, both an AHL-producing nonmucoid revertant (NH57388C) from the mucoid isolate (NH57388A) and a nonmucoid isolate (NH57388B) deficient in AHL were almost cleared from the lungs of the mice. This model, in which P. aeruginosa is protected against the defense system of the lung by alginate, is similar to the clinical situation. Therefore, the mouse model provides an improved method for evaluating the interaction between mucoid P. aeruginosa, the host, and antibacterial therapy.