In vitro stability of a novel compliant poly(carbonate-urea)urethane to oxidative and hydrolytic stress.

Poly(ester)urethane and poly(ether)urethane vascular grafts fail in vivo because of hydrolytic and oxidative degradative mechanisms. Studies have shown that poly(carbonate)urethanes have enhanced resistance. There is still a need for a viable, nonrigid, small-diameter, synthetic vascular graft. In this study, we sought to confirm this by exposing a novel formulation of compliant poly(carbonate-urea)urethane (CPU) manufactured by an innovative process, resulting in a stress-free. Small-diameter prosthesis, and a conventional poly(ether)urethane Pulse-Tec graft known to readily undergo oxidation in a variety of degradative solutions, and we assessed them for the development of oxidative and hydrolytic degradation, changes in elastic properties, and chemical stability. To simulate the in vivo environment, we used buffered solutions of phospholipase A(2) and cholesterol esterase; solutions of H(2)O(2)/CoCl(2), t-butyl peroxide/CoCl(2) (t-but/CoCl(2)), and glutathione/t-butyl peroxide/CoCl(2) (Glut/t-but/CoCl(2)); and plasma fractions I-IV, which were derived from fresh human plasma centrifuged in poly(ethylene glycol). To act as a negative control, both graft types were incubated in distilled water. Samples of both graft types (100 mm with a 5.0-mm inner diameter) were incubated in these solutions at 37 degrees C for 70 days before environmental scanning electron microscopy, radial tensile strength and quality control, gel permeation chromatography, and in vitro compliance assessments were performed. Oxidative degradation was ascertained from significant changes in molecular weight with respect to a control on all Pulse-Tec grafts treated with t-but/CoCl(2), Glut/t-but/CoCl(2), and plasma fractions I-III. Pulse-Tec grafts exposed to the H(2)O(2)/CoCl(2) mixture had significantly greater compliance than controls incubated in distilled water (p < 0.001 at 50 mmHg). No changes in molecular weight with respect to the control were observed for the CPU samples; only those immersed in t-but/CoCl(2) and Glut/t-but/CoCl(2) showed an 11% increase in molecular weight to 108,000. Only CPU grafts treated with the Glut/t-but/CoCl(2) mixture exhibited significantly greater compliance (p < 0.05 at 50 mmHg). Overall, results from this study indicate that CPU presents a far greater chemical stability than poly(ether)-urethane grafts do.     

Ischemic necrosis of the entire femoral head and rapidly destructive hip disease: potential causative relationship

 Objective. Rapidly destructive hip disease (RDHD) is an uncommon disorder of the hip that has been considered a disease of unknown cause and distinct from ischemic necrosis of the femoral head. The objective of this study was to investigate ischemic necrosis of the femoral head as one potential cause of RDHD. Design and patients. In 600 patients who underwent MR imaging of the hip, 20 cases of ischemic necrosis involving the entire femoral head in 18 patients (3%) were retrospectively studied with routine radiography and MR imaging. All patients had surgically confirmed ischemic necrosis of the femoral head. Results and conclusions. All patients showed rapid destruction of the femoral head on routine radiography and MR imaging as compared with the gradual onset of clinical symptoms. Plain radiographs showed several bone fragments at the inferomedial aspect of the femoral head (75%), acetabular erosions (55%), eccentric depression at the lateral articular surface of the femoral head conforming to the adjacent acetabulum (35%), and mild osteoarthritis (15%). Bone sclerosis was often present at sites of impaction between the femoral head and the acetabulum. MR imaging showed marked distention of the joint capsule in all cases. In 14 of 20 cases, the contents of the joint space showed predominantly low or intermediate signal intensity on T1- and T2-weighted images. Ischemic necrosis involving the entire femoral head may represent one of the causes of RDHD.     

中医药学研究方法的解构与特性分析

将中医药学研究方法从观念理论、核心方法和技术手段3个方面进行解构，并对其内在特性进行详细分析。明确提出中医药学研究方法的范式特性、观念理论的思辨性、核心方法的主观性以及整体刚性和局部柔性的特性，揭示了中医药研究方法的优势与不足，为中医药研究方法论的创新提供理论依据。     

Solitary Small Hepatic Angiosarcoma: Initial and Follow-up Imaging Findings

We report an uncommon case of solitary, small hepatic angiosarcoma that was initially considered as a hemangioma. We present the imaging findings, with an emphasis on the initial and follow-up CT and MR findings, as well as report on the more suggestive findings of angiosarcoma than those of a hemangioma.     

Treatment of persistent and recurrent nasopharyngeal carcinoma by brachytherapy

The early results of brachytherapy for persistent and recurrent nasopharyngeal carcinoma in 30 patients is presented. Fifteen patients were treated by intracavitary caesium, 12 patients were treated by interstitial gold grain implant using the split-palate approach and three patients were treated by both intracavitary caesium and interstitial gold grain implant for the first and second relapse in the nasopharynx, respectively. The overall tumour control rate for intracavitary caesium was 5/18 (28%) with median follow-up of 25.2 months, and for interstitial gold grain implant it was 9/14 (64%) with median follow-up of 16.5 months. Interstitial gold grain implantation appears to be effective in the treatment of persistent and recurrent nasopharyngeal carcinoma.     

Staphylococcal toxins: screening of burn wound isolates and evidence for alphahaemolysin production in the burn wound

Culture filtrates of Staphylococcus aureus strains isolated from burn patients were examined for cytotoxic activities. A large molecular weight cytotoxin (MW=253000 daltons) that exhibited cytotoxicity for human foreskin cells and haemolytic activity against human and rabbit erythrocytes was identified. The cytotoxic activity could be completely neutralized by antiserum formed against the cytotoxin. Further characterization of the molecule by isoelectric focusing revealed that the cytotoxin was composed of at least two toxic factors of smaller molecular weight. Both factors exhibited cytotoxicity to tissue-culture cells. however, one factor lysed rabbit but not human erythrocytes whereas the other factor had the opposite haemolytic pattern. The cytotoxicity of each factor was neutralized by the antiserum formed against the cytotoxin. A cytotoxic factor that exhibited haemolytic activity for rabbit erythrocytes, and that was neutralized by the cytotoxin antiserum, was identified in burn wound extracts of mice infected with Staph. aureus. On the basis of molecular weight and isoelectric focusing data, we conclude that the large molecular weight cytotoxin was composed of an aggregation of alpha-haemolysin and another presently unidentified toxic molecule, possibly delta-toxin. Alpha-haemolysin appears to be produced in vivo during experimental staphylococcal burn wound infection.     

凝血酶受体结构与功能的研究现状

凝血酶（ｔｈｒｏｍｉｂｉｎ，Ⅱａ）是一种生成于损伤处血管内皮细胞多功能蛋白酶，它是参与凝血过程各个环节反应中的关键酶。在发挥止血作用的同时，还可能诱导炎症、增生及修复等反应。最近发现的凝血酶受体（ｔｈｒｏｍｂｉｎ ｒｅｃｅｐｔｏｒ，ＴＲ）分子可能为解释上述现象提供了一个理论框架。同时，ＴＲＮ端被Ⅱａ切下的４１个氨基酸片段是否具有特殊功效，值得研究探讨。     

Renal metastasis from choriocarcinoma: MRI appearance

Choriocarcinoma is the most malignant tumor of gestational trophoblastic neoplasia. It grows rapidly and metastasizes to the lung, liver, and, less frequently, to the brain. Renal involvement is rare. Magnetic resonance imaging (MRI) is a useful modality to image the affected tissues; it contributes to the evaluation and management of the disease. One case of renal choriocarcinoma with MRI evaluation is reported. Received: 24 February 1997/Accepted: 14 April 1997     

Angiostrongylus (Parastrongylus) eosinophilic meningitis

Angiostrongylus (Parastrongylus) cantonensis is the commonest cause of eosinophilic meningitis in the world. Infective third-stage larvae develop in slugs and snails. Humans are infected primarily in the central nervous system after ingesting an infected intermediate host. Damage by motile worms, inflammatory responses to foreign bodies, and possible toxicity of worm substances work in concert to produce the pathologic and clinical picture of neurologic angiostrongyliasis. This disease manifests itself by headache, paresthesias, generalized weakness, and occasionally visual disturbances and extraocular muscular paralysis. Eosinophilic pleocytosis is the major laboratory finding. Although the diagnosis of neurologic angiostrongyliasis is usually made clinically, serologic methods such as ELISA (enzyme-linked immunosorbent assay) can be helpful. Occasionally, living larvae can be identified histologically in the CSF, eye, or other tissue. There is no specific treatment for this disease. Corticosteroids may be useful to relieve increased intracranial pressure. The role of anthelmintic drugs, such as thiabendazole and ivermectin, is not yet known. The prognosis of neurologic angiostrongyliasis is usually good; however, fatal and chronic cases do occur. Appropriate preparation of food, control of mollusks and planarians, and elimination of rodents are important measures in limiting the further spread of eosinophilic meningitis caused by A. cantonensis.