红细胞悬液传感器的研制

以人红细胞作为过氧化氢酶的来源，用尼龙网共价键合，并与氧电极合制得过氧化氢传感器，研究了尼龙网上活化酶的固定化，测试介质等有关实验条件和参数，测得在ｐＨ８的磷酸盐缓冲溶液中，电极响应的线性范围为３×１０＾－５～３×１０＾－３ｍｏｌ／Ｌ，测定了传感器在果珍，鱼浆和磷酸盐缓冲溶液中对过氧化氢的回收率，获得满意结果。     

Persistence and extinction in a mathematical model of cell populations affected by radiation

A mathematical model consisting of a system of two ordinary differential equations is formulated to represent the interrelationship between healthy and radiated cells at a given cite. Three different modes of radiation are considered: constant, decaying, and periodic radiation. For the constant case, precise criteria for persistence and extinction are obtained. In the decaying case, it is shown that the radiated cells always become extinct. Finally in the periodic case, criteria are obtained for a perturbed positive periodic solution. Dedicated to the memory of Professor Miklós Farkas     

Controlling the bugs

In late 1984, the Reagan administration proposed a Coordinated Framework for Regulation of Biotechnology. Its proposed regulatory approach appears less constraining than the deep concerns of the 1970s concerning the risk of biotechnology would have suggested. Several distinctive characteristics of the early period of biotechnology, particularly the role of the research community in developing the initial regulatory system and the extent of federal funding, explain this development. The administration’s proposal may attract substantial support. However, implementation may lead to conflicts and problems, especially concerning human germ-line gene therapy and environmental release of viable genetically engineered organisms.     

Organotins: Toxicology and biological effects

Organotins are currently one of the most studied groups of organometallic compounds; their novel and often unique chemical properties have intrigued chemists for over 100 years and, today, many of these compounds find extensive use in agriculture and industry. Over the years, however, a number of the organotins have been demonstrated to be toxic and there is now increasing concern that their widespread use may cause adverse effects within environmental and biological systems. This article reviews and updates the current literature concerning organotin toxicology. It identifies the various target organs and systems, discusses mechanisms and species susceptibility, and directs the reader to additional sources of more specialized information as appropriate.     

Proton spin relaxation studies of fatty tissue and cerebral white matter

Proton spin longitudinal (T1) and transverse (T2) relaxation and proton density studies were carried out on human fatty tissue and bovine white matter, both in the native state and after immersion in D2O. It is concluded that nuclear magnetic resonance signals from fatty tissue result mainly from methyl and methylene protons of hydrocarbons. No contribution from lipid protons could be detected for white matter, although it contains a high percentage of lipids. Imaging experiments, resulting in T1, T2, and proton density maps, support the results obtained with spectroscopic relaxation studies.     

Risk evaluation and protection against ionizing radiation

The advent of nuclear reactors ushered in an era of increasing number of sources of ionizing radiations. However, the potential of ionizing radiations to cause harmful effects was recognized soon after the discovery of x-rays and radioactivityi.e. long before the building of nuclear reactors. Therefore, protection against ionizing radiations has been of paramount concern and has guided the development of atomic energy and related fields. The advances in technology in general resulted in an increase in accidents causing injury and death. It was realised that even medicines, food additives and a host of other substances of daily use had injurious side effects. Smoking was found to be extremely harmful. From these emerged the concepts of quantitative and relative risks. This article discusses briefly the concept of riskvis-a-vis ionizing radiations and approaches to protection against them.     

Frequency-domain fluorescence lifetime imaging for endoscopic clinical cancer photodetection: Apparatus design and preliminary results

We describe a new fluorescence imaging device for clinical cancer photodetection in hollow organs in which the tumor/normal tissue contrast is derived from the fluorescence lifetime of endogenous or exogenous fluorochromes. This fluorescence lifetime contrast gives information about the physicochemical properties of the environment which are different between normal and certain diseased tissues. The excitation light from a CW laser is modulated in amplitude at a radio frequency by an electrooptical modulator and delivered by an optical fiber through an endoscope to the hollow organ. The image of the tissue collected by the endoscope is separated in two spectral windows, one being the backscattered excitation light and the other the fluorescence of the fluorochrome. Each image is then focused on the photocathode of image intensifiers (II) whose optical gain is modulated at the same frequency as the excitation intensity, resulting in homodyne phase-sensitive images. By acquiring stationary phase-sensitive frames at different phases between the excitation and the detection, it is possible to calculate in quasi-real time the apparent fluorescence lifetime of the corresponding tissue region for each pixel. A result obtained by investigating the endogenous fluorochromes present in the mucous membrane of an excised human bladder is presented to illustrate this method and most of the optical parameters which are of major importance for this photodetection modality have been evaluated.     

Dimeric Cyclodextrin Carriers with High Binding Affinity to Porphyrinoid Photosensitizers

The aim of our investigation was to develop carrier systems for an application of inert drugs in photodynamic cancer therapy. -Cyclodextrin dimers linked at their primary and secondary faces by spacers of varying lengths were synthesized as carrier systems. The binding constants of the inclusion complexes of these cyclodextrin dimers and porphyrinoid photosensitizers were determined by competitive spectrofluorometry. Particularly the secondary face linked dimers exhibited extremely high binding constants with values of 106-107 L/mol. Theoretical studies were carried out on these inclusion complexes to confirm the influence of spacer length and connecting side on complex stability.     

高效液相色谱法测定血清中的鸟氨酸脱羧酶活性

建立了血清中鸟氨酸脱羧酶活性的高效液相色谱测定法。结果表明，腐胺在２．８～４５．５μｍｏｌ／Ｌ范围内线性关系良好。最低检测量为０．０５ｎｍｏｌ，回收率为８５．０６％，ＲＳＤ为８．９１％。本法测定正常人及乳腺癌、宫颈癌患者血清中的鸟氨酸脱羧、酶活性发现，乳腺癌及宫颈癌血清中的酶活性升高（ｐ＜０．０５），说明测定血清的鸟氨酸脱羧酶活性，对诊断肿瘤有一定的临床意义。