The use of acoustic microscopy to study the mechanical properties of glass-ionomer cement.

OBJECTIVES: The aim of the study was to investigate the relationship between microstructure, acoustic and mechanical properties of hardened dental cement samples, prepared with different powder/water ratios. METHODS: Glass-ionomer dental cement samples, prepared with a standard amount of cement powder and different amounts of water have been examined after being hardened. Surface microstructure and ultrasound, longitudinal and shear velocities were obtained with a scanning acoustic microscope. Conditional effective elastic modulus and Poisson's ratio have been calculated using longitudinal and shear sound velocity values. Then on the same samples elastic modulus and microhardness have been determined by standard tests. Additional samples have been used to determine compressive strength. RESULTS: Density; conditionally instantaneous elastic modulus; high-elasticity modulus and compression strength of the samples decrease when large amounts of water were used for their preparation. At the same time porosity and microhardness of the cement matrix increase. Acoustic parameters and parameters of elasticity, calculated on the basis of sound velocity, demonstrated changes, similar to those obtained in standard mechanical tests. SIGNIFICANCE: The established relation between microstructure, acoustic and mechanical parameters demonstrated a high capacity of acoustic microscopy application for non-destructive characterization of dental materials. A particular advantage of the acoustic microscopy is the opportunity to evaluate microstructure and mechanical properties on the same sample.     

肠道T细胞淋巴瘤临床分析

本文总结报告了3例肠道T细胞淋巴瘤(intestinal T-cell lymphoma，ITCL)的诊治资料，并结合文献复习，发现IT—CL多见于中年男性，以腹痛、血便、发热、体质量下降为主要症状，治疗效果差，预后不良。病理改变以肠道溃疡形成为特点，溃疡形态呈多形性、多灶性、不规则，镜下瘤细胞明显异型、弥漫性浸润，中至大细胞多见。肿瘤细胞呈T细胞表型。ITCL临床少见，缺乏特异性临床表现，极易误诊。故临床医师应重视对ITCL临床病理特征、免疫表型和基因型的研究，注意识别，促其早期诊治。     

Affinity of Macrocyclic Pyridinophanes and Their Acyclic Analogs to Peripheral Benzodiazepine CNS Receptors

Pharmaceutical Chemistry Journal -     

Intramolecular Thermal Condensation of 3-Acetyl-5-Oxopyrazolo[1,5-a]quinoline-4-ethylcarboxylate: a Simple Pathway to the New Tetracyclic System Containing Fluoroquinolone Fragment

Pharmaceutical Chemistry Journal -     

感染日本血吸虫的家兔治疗前后肝纤维化动态观察

感染日本血吸虫的家兔治疗前后肝纤维化Ｂ超声像图模型、血清ＭＡＯ水平及病理学结果表明，血吸虫引起的肝纤维化变化过程与血清ＭＡＯ水平升降趋势趋向一致，均在１８周达到高峰。解剖与病理学检查结果基本相符，血吸虫性肝纤维化形成后，只要及时给予杀虫治疗，肝纤维化部分可发生逆转。     

Loss of Anticoagulant Effect of Heparin During Circulation of Human Blood In Vitro

Device-induced thrombogenesis was studied in an in vitro model using human blood circulated through an artificial ventricle. A new constant pressure filtration technique was used to detect circulating microemboli, the activated partial thromboplastin time (APTT) test was used to monitor the blood for the presence of anticoagulant activity of heparin, and hemolysis was quantified by measuring the plasma free hemoglobin level. Circulation of blood through a 20-ml stroke volume pneumatically driven ventricle for 6-9 h resulted in a significant reduction of APTT, indicating the loss of the anticoagulant effect of heparin. Microemboli concentration was minimal until the APTT decreased below 125 s, at which time the microemboli concentration increased rapidly. This was presumed to be due to the formation of thrombi following a decrease in heparin activity. A significant increase in hemolysis was also noted when blood was pumped. None of these changes was noted in the nonpumped control blood. Spontaneous loss of heparin activity in blood circulated by a pneumatically driven pump may have clinical implications and may help understanding of the problems associated with device-induced thrombogenesis.     

Effects of acute barbiturate administration, tolerance and dependence on brain GABA system: comparison to alcohol and benzodiazepines

Central nervous system depressants, e.g., barbiturates, alcohol and benzodiazepines, have a wide spectrum of activity in humans and animals. Evidence accumulated suggests that some of the pharmacological actions exerted by these agents may be mediated through GABA system by mimicking GABAergic transmission. This review attempts to summarize the evidence available as to how the GABA system plays a part in the barbiturate actions and the development of tolerance to and physical dependence on barbiturates. The comparisons of the effects of alcohol, barbiturates and benzodiazepines at different steps of GABA synapse are also presented. Furthermore, the results which have been reported in the literature are inconsistent. This may be due to differences in: (a) animal models used; (b) brain regions used; (c) protocols (dose, duration, form and route of administration, etc.) used in treating animals and/or (d) techniques (pharmacological, biochemical, physiological, etc.) used.     

Elicitins from Phytophthora and basic resistance in tobacco.

Elicitins are a family of small proteins secreted by species of Phytophthora. They are thought to be major determinants of the resistance response of tobacco against these oomycetes, since purified elicitins, alone and at low concentrations, can induce vigorous defense responses in tobacco (i.e., hypersensitive cell death and resistance against subsequent pathogen attack), and in vitro elicitin production by Phytophthora isolates is strongly negatively correlated with their pathogenicity on tobacco plants. A number of elicitins have been purified and their amino acid sequences have been determined and found to be conserved. A three-dimensional structure for elicitin is emerging from nuclear magnetic resonance studies. Two structural classes, alpha and beta, are distinguished by their biological effects when applied to decapitated stems or petioles; the beta class causes more necrosis on leaves and provides better subsequent protection against pathogen attack. However, both these classes of elicitins will similarly cause necrosis when each is, instead, directly infiltrated into tobacco leaf panels. Effects of elicitins on tobacco cells include rapid electrolyte leakage, changes in protein phosphorylation and amounts of active oxygen species, and later production of ethylene and capsidiol. The sites of initial interaction with tobacco cells are unknown, but the interaction appears to induce general defense-related responses.