Curing efficiency and ocular hazards of dental photopolymerization sources

The spectral distributions of a range of dental photocuring sources were measured at the exit window and at a distance of 10 cm. The former enabled the evaluation of a newly proposed photocuring efficiency index which correlates well with the depth of cure of the photopolymerized resins, thus providing a basis for the comparison of different photocuring sources. The spectral irradiante of the sources obeyed the inversesquare law, allowing a comparison with the ACGIH threshold limit values. According to these criteria, no ocular hazard is posed to the patient or clinician by u.v.-A or u.v.-B radiation nor to the patient by the visible light when momentarily exposed to the sources. Similarly the ACGIH criterion indicates that the clinician does not risk chorioretinal injury provided the exposure is restricted to less than 140 s in a 3 h period.     

Structure and properties of methacrylate based dental restorative materials

The chemistry and structure of the dimethacrylate resins and the nature of the filler systems in dental composite resins are reviewed in relation to their influence on the setting behaviour, dimensional stability, aesthetics, fracture behaviour and adhesive potential. It is clear that a deeper understanding of the structure of the polymeric matrix and the mechanism of clinical wear is required. As a result of ongoing research in this area and with the development of dentine adhesives, the future prospects of composite resins are encouraging.     

Evaluation of endocrine disrupting activity of plasticizers in polyvinyl chloride tubes by estrogen receptor alpha binding assay

Polyvinyl chloride (PVC) tubing is an indispensable medical material for extracorporeal circulation therapy. However, di(2-ethylhexyl)phthalate (DEHP), a suspected endocrine disruptor, can be eluted from PVC, suggesting that an alternative material that does not contain DEHP is needed for clinical applications. First, we evaluated the endocrine disrupting risks of the plasticizers contained in PVC tubes by investigating their binding affinities for the human estrogen receptor alpha (ERα). Our results revealed that, while DEHP has some binding affinity for ERα, neither epoxidized soybean oil nor tris(2-ethylhexyl)trimellitate (an alternative to DEHP) has any affinity for ERα. Second, we evaluated the endocrine disrupting risks of a tube made of newly developed plasticizer-free (PF) materials. We confirmed the presence of DEHP and detected several unidentified substances in plasma stored within the PVC tube. This plasma's competitive binding affinity for ERα was significantly higher than that of control plasma (P < 0.01). In contrast, the profile of plasma stored in the PF tube was similar to that of the control, both in terms of high-performance liquid chromatography chromatograms and competitive binding capacity for ERα, suggesting that the PF tube is biocompatible and is useful for reducing the elution of substances capable of binding to ERα. Presented in part at the 42nd Congress of the Japanese Society for Artificial Organs, October 5–7, 2004, Tokyo, Japan     

用于预防术后粘连的可吸收高分子材料研究进展

粘连是结缔组织纤维带与相邻的组织或器官结合在一起而形成的异常结构；其经常在妇产科、心胸外科和脊柱外科手术后出现。粘连是引发术后并发症的主要原因之一。在目前预防粘连的诸多方法中，采用高分子材料作为隔离物是一种有效的途径。本综述了近年来用于预防粘连的各种可吸收高分子材料，其中包括壳聚糖、聚乙二醇、透明质酸、纤维素等。并且介绍了经过化学改性、物理共混、表面接枝等方法获得的许多新型聚合物。这些材料可以制成溶液、薄膜、凝胶等不同形式使用；而且既可以单独使用，也可与抗粘连药物结合使用。     

Transport of urea and amino acids through the isolated human placenta

By means of a method of two-way perfusion of the isolated human placenta the transport of urea from the fetal to the maternal placental circulation and the transport of amino acids in the opposite direction were studied. Experiments showed that the method provides for sufficiently complete perfusion of the intervillous space and creates suitable conditions for the study of placental transport. If the amino nitrogen concentrations in the two circulatory systems are equal, its concentration in the fetal circulation rises in the course of the experiment. On the addition of an amino acid to the maternal circulation, this increase develops to a greater degree. The results of these experiments confirm the view that amino acids are secreted by trophoblast cells into the fetal circulation.Laboratory of Biochemistry, Institute of Obstetrics and Gynecology, Academy of Medical Sciences of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR M. A. Petrov-Maslakov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 4, pp. 394–397, April, 1976     

抗骨肉瘤药物纳米载体的研究进展

骨肉痛是最常见的恶性骨肿瘤,病死率较高。而生物医用纳米材料是纳米材料和生物材料交叉的一个全新领域,在生物医学上有着十分诱人的、广泛的应用前景。本文对纳米无机生物材料、纳米高分子生物材料、纳米复合生物材料作为抗骨肉瘤药物载体的研究进展作了较全面的综述。     

Viruses Infecting Marine Brown Algae

Viruses infecting algal hosts possess large double-stranded DNA as genomes. We have recently identified a family of viruses specific for filamentous brown algae. In contrast to the better known Chlorella viruses with their lytic infection cycle, marine brown algal viruses latently occur in their host cells and are induced to multiply in response to a variety of external stimuli such as change in light and temperature. Here, I summarize the known properties of this family of viruses and discuss their taxonomic classification.     

纳米材料在组织工程体外细胞培养中的应用进展

组织工程包括细胞和生物支架两部分.其中细胞的活性在很大程度上取决于支架材料的优劣.良好的生物支架应该能尽可能地模拟细胞在体内的内环境,从而提供细胞生长所需的微环境.纳米材料由于很好地模拟了细胞在体内的拓扑结构,从而在组织工程领域得到了越来越广泛的应用.综述了纳米材料在各种细胞体外培养中的作用,初步探讨了纳米材料对细胞促进作用的机制,并对纳米材料在肝脏组织工程中的应用进行了展望.     

人工髓核材料(半晶聚乙烯醇水凝胶弹性体)的研制

研制一种可替代椎间盘髓核并恢复其功能的生物医用材料 ,探讨半晶聚乙烯醇水凝胶弹性体材料临床应用的可行性。聚乙烯醇 (PVA)水溶液在 - 2 0℃下冷冻 6～ 12 h,室温下融化 1～ 2 h,上述过程重复 1～ 3次 ,然后对试样进行真空脱水 ,制得人工髓核材料 (半晶 PVA水凝胶弹性体 )。差示扫描量热法 (DSC)和力学性能试验研究了 PVA水溶液浓度、真空脱水和 γ射线辐照对水凝胶 PVA的结晶度和力学性能的影响     

Three species of Philometra (Nematoda, Philometridae) from marine fishes off Corsica, France

Gravid or subgravid females of the following three species belonging to the nematode genus Philometra were collected from marine perciform fishes of the Bonifacio Strait Marine Reserve, Corsica, France: Philometra justinei sp. nov. (prevalence 1.5%, intensity 11) and Philometra sp. (prevalence 3%, intensity 2) from the abdominal cavity and gonads, respectively, of the striped red mullet Mullus surmuletus (Mullidae), and Philometra serranellicabrillae Janiszewska, 1949 (prevalence 27%, intensity 2–6) from the gonads of the comber Serranus cabrilla (Serranidae). The newly described species, P. justinei, is mainly characterized by the absence of an anterior bulbous inflation of the oesophagus, body length of the gravid female (196 mm), conspicuously large amphids, number and distribution of cephalic papillae, and the morphology of larvae. It is the second known species of Philometra parasitizing fishes of the family Mullidae and the ninth species of this genus reported from marine fishes of the Mediterranean region. P. serranellicabrillae, studied for the first time by SEM, is redescribed.