CELL SURFACE DAMAGE IN CULTURED MAMMALIAN CELLS WITH SYNCHROTRON RADIATION AT 160 nm

Cultured mammalian cells (HeLa) were allowed to attach onto a membrane filter and were irradiated with 160 nm synchrotron radiation. The cells then were rinsed with medium, fixed, and stained. Some of the cells became detached from the membrane filter during irradiation before post-irradiation incubation at 37°C. The cells remaining attached to the membrane filter were released by trypsinization, collected and examined for dye-exclusion ability with eosin Y. The number of stained cells was increased when the cells were irradiated at 160 nm, while no such increase was observed in cells irradiated with synchrotron radiation at 220 nm, with a low pressure Hg lamp (predominantly 254 nm), or with gamma-rays of ⁶⁰Co. These results indicated that the cell surface was injured by irradiation with synchrotron radiation at 160 nm.     

AVERAGE LATITUDINAL VARIATION IN ULTRAVIOLET RADIATION AT THE EARTH''S SURFACE

Abstract— Tabulated values are presented for ultraviolet radiation at the earth's surface as a function of wavelength, latitude, and season, for clear sky and seasonally and latitudinally averaged ozone amounts. These tabulations can be combined with any biological sensitivity function in order to obtain the seasonal and latitudinal variation of the corresponding effective doses. The integrated dosages, based on the erythemal sensitivity curve and on the Robertson-Berger sunburn-meter sensitivity curve, have also been calculated, and these are found to vary with latitude and season in very nearly the same way as 307 and 314 nm radiation, respectively.     

THE TIME-RESOLVED PHOTON-COUNTING FLUOROMETER AT THE NATIONAL SYNCHROTRON LIGHT.SOURCE

A single-photon-counting fluorometer, capable of steady-state and time-dependent measure-ments, is now operational at port U9B of the National Synchrotron Light Source at Brookhaven National Laboratory. Excitation wavelengths are selected by a prism-grating double monochromator. Emission energies are chosen by filter(s) or by a one-meter Spex monochromator. Commercial electronics are used for data acquisition, except for special circuitry required by the high (53 MHz) repetition rate of the synchrotron. A large sample chamber allows flexibility in arranging optical components and samples. The standard optical configuration of the sample chamber consists of a focusing mirror, a six position excitation optic wheel, a turntable with four thermostatted cuvette holders, a six position emission optic wheel, and an f/0.7 emission collection lens. Data acquisition and the setting of correct wavelengths and sample chamber optics are controlled by a Tektronix 4052 computer via the IEEE-488 General Purpose Interface Bus. Time-dependent fluorescence data are transferred to a VAX 11/730 for analysis; current deconvolution software includes nonlinear least-squares programs for single curve and global analysis.     

SOLAR ULTRAVIOLET RADIATION AT THE EARTH'S SURFACE

The biologically effective ultraviolet irradiance at the earth's surface varies with the elevation of the sun, the atmospheric ozone amount, and with the abundance of scatterers and absorbers of natural and anthropogenic origin. Taken alone, the reported decrease in column ozone over the Northern Hemisphere between 1969 and 1986 implies an increase in erythemal irradiance at the ground of four percent or less during summer. However, an increase in tropospheric absorption, arising from polluting gases or particulates over localized areas, could more than offset the predicted enhancement in radiation. Any such extra absorption is likely to be highly regional in nature and does not imply that a decrease in erythemal radiation has occurred on a global basis. The Antarctic 'ozone hole' represents a special case in which a portion of the earth has experienced ultraviolet radiation levels during spring that are far in excess of those which prevailed prior to the present decade.     

检测实验室如何开展质量体系内部审核工作

详细论述了审核的基本概念、开展质量体系内部审核工作的必要性、如何开展质量体系内部审核工作以及中国实验室国家认可委员会的有关政策。     

小剂量电离辐射对生物体的作用

本文调研了国内外有关小剂量电离辐射对生物体作用的实验研究。许多实验结果指出,辐射引起生物体近期辐射损伤的阈值一般不低于01Gy,并且小剂量电离辐射对机体免疫功能有促进作用,小剂量预辐照后能对大剂量辐照产生适应性。因此,有学者提出小剂量有益的观点,很具有启发性。然而由于对小剂量辐射生物效应的资料掌握不够,对小剂量照射还需要继续进行深入的研究。     

SPECTROSCOPIC PROPERTIES OF PSORALEN DERIVATIVES SUBSTITUTED BY CARBETHOXY GROUPS AT THE 3,4 AND/OR 4,5' REACTION SITE

Abstract— The newly synthesized linear psoralen derivative 3-carbethoxypsoralen has been shown recently to behave as a monofunctional derivative and has attracted some interest in the psoriasis treatment. In a first attempt to understand, by the fluorescence technique, the molecular mechanism by which it interacts with DNA, a spectroscopic study of the molecule was undertaken. The fluorescence of 3-carbethoxypsoralen at room temperature resembles that of 8-methoxypsoralen with a ten times higher quantum yield. 365 nm irradiation of dilute solutions of 3-carbethoxypsoralen rapidly leads to the formation of two types of highly fluorescent photoproducts. Type 1 photoproducts (λ_em^max= 425 nm, λ_exc^max= 360 nm) have been identified as the result of the addition of a solvent molecule to the 4,5' reaction site of the molecule. Their fluorescence intensity is a hundred times higher for 3-carbethoxypsoralen than for 8-methoxypsoralen. They become negligible when the 4',5' reaction site carries also a carbethoxy group. Type 2 photoproducts exhibit a somewhat different emission (λ_em^{max =} 443 nm, λ_exc^max= 413 nm). They are probably the result of an opening of the furocoumarin molecule. The implications of the peculiar photochemical properties of 3-carbethoxypsoralen are discussed in view of its biological activity. In addition, the use of fluorescence in monitoring the photobinding of psoralens to DNA is also discussed     

721型分光光度计分光系统常见故障的排除

721型分光光度计分光系统的常见故障有无出射单色光或光斑不完整、单色光波长指示值与实测值不一致、波长调节器转动时出射光波长无变化、波长调节器转动困难且波长读数盘不动等，分析了造成这类故障的原因，并阐述了排除这类故障的方法。     

SPECTROSCOPIC PROPERTIES OF THE POTENTIOMETRIC PROBE MEROCYANINE-540 IN SOLUTIONS AND IN LIPOSOMES

Absorption, fluorescence and resonance Raman spectra of the membrane dye merocyanine-540 (MC540) were measured. The aggregation of the dye, its binding to lipid membranes and its response to crossmembrane electric potential differences were studied. The dye was found to aggregate even at micromolar concentrations in water, but not in organic solvents. The dimerization constant was evaluated by spectroscopic techniques. The binding constant to liposomes was estimated by a spectroscopic titration method. Resonance Raman spectra of MC540 were measured for the first time. Distinct changes were observed in the vibrational spectrum upon the generation of a valinomycin-induced K⁺ diffusion potential (Nernst potential) on liposomes. The ratio of Raman band intensities, which was found to be related to the membrane potential, can be used to evaluate the absolute value of the electric potential.     

COPOLYMERS OF CHLOROETHYL METHACRYLATE, GLYCIDYL METHACRYLATE, AND METHYL METHACRYLATE AS SYNCHROTRON RADIATION x-RAY PHOTORESISTS

The copolymers of chloroethyl methacrylate (CMA), glycidyl methacry-late (GMA), and methyl methacrylate (MMA) were synthesized in benzene solution. Theirbreadths of the molecular weight distributions are 2.1 and 2.3, respectively The ther-mal stability of P(GMA-CMA) is superior to that of P(CMA-MMA). The resolutionsof P(CMA-MMA) and P(GMA-CMA) photoresists were found to be 0.1～0.16μm and0.17 ～0.2μm, respectively.     

水平测试样品的均匀性保证

为确保水平测试样品的均匀性，文中阐述了水平测试、样品制备、均匀性检验的取样数量、取样方式、最小取样量、测量方法和统计方法，重点介绍了均匀性检验的统计方法。     

THE IMPORTANCE OF THE MICROENVIRONMENT SURROUNDING A CHROMOPHORE IN DETERMINING ITS SPECTROSCOPIC BEHAVIOR*

Se pone especial énfasis en la importancia del microambiente de un grupo como factor determinante del comportamiento fotoquímico, emisión y dicroismo circular de móleculas biológicas. Los ejemplos dados incluyen la fotoquímica de la ribonucleasa, la dependencia de las propiedades luminiscentes de amino acidos aromáticos con la temperatura, y el comportamiento espectroscópico de los dinucleótidos.     

THE EFFECT OF ALA AND RADIATION ON PORPHYRIN/HEME BIOSYNTHESIS IN ENDOTHELIAL CELLS

To study porphyrin biosynthesis in human microvascular endothelial cells, HMEC-1 cells, a transformed human microvascular endothelial cell line, were incubated with 5-aminolevulinic acid (ALA), the precursor of endogenous porphyrins, and porphyrin accumulation was measured spectro-fluorometrically. The HMEC-1 cells accumulated porphyrin in a concentration-related and a time-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated in the cells. The effect of light on protoporphyrin accumulation was evaluated by exposing the ALA-loaded HMEC-1 cells to ultraviolet-A (UVA) and blue light, followed by another incubation with ALA for 2–24 h. Enhancement of protoporphyrin accumulation in irradiated HMEC-1 cells was observed 2–24 h after irradiation, which was associated with a decrease in ferrochelatase protein and activity. Porphyrin accumulation from ALA after irradiation was significantly decreased when catalase (750–3000 U/mL, 29.3–44.3% suppression) or superoxide dismutase (270 U/mL, 36.4% suppression) was present during irradiation. These data demonstrate that HMEC-1 cells were capable of porphyrin biosynthesis, and that exposure of protoporphyrin-containing HMEC-1 cells to UVA and blue light, which includes the Soret band spectrum, decreased the ferrochelatase activity and its protein. These changes were mediated, at least in part, by reactive oxygen species.     

INACTIVATION ACTION SPECTRA OF BACILLUS SUBTILIS SPORES IN EXTENDED ULTRAVIOLET WAVELENGTHS (50–300nm) OBTAINED WITH SYNCHROTRON RADIATION

Five types of Bacillus subtilis spores (UVR, UVS, UVP, RCE, and RCF) differing in repair and/or recombinational capabilities were exposed to monochromatic radiations at 13 wavelengths from 50 to 300 nm in vacuum. An improved biological irradiation system connected to a synchrotron radiation source was used to produce monochromatic UV radiation in this extended wavelength range with sufficient fluence to inactivate bacterial spores. From the survival curves obtained, the action spectra for the inactivation of the spores were depicted. Recombination-deficient RCE (recE) and RCF (recF) spores were more sensitive than the wild-type UVR spores in the entire range of wavelengths. This was considered to mean that DNA was the major target for the inactivation of the spores. Vacuum-UV radiations of 125-175 nm were effective in killing the spores, and distinct peaks of the sensitivity were seen with all types of the spores. Insensitivities at 190 and 100 nm were common to all five types of spores, indicating that these wavelengths were particularly impenetrant and absorbed by the outer layer materials. The vacuum-UV peaks centering at 150 nm were prominent in the spores defective in recombinational repair, while the far-UV peaks at around 235 and 270 nm were prominent in the UVS (uvrA ssp) and UVP (uvrA ssp polA) spores deficient in removal mechanisms of spore photoproducts. Thus, the profiles of the action spectra were explained by three factors; the penetration depth of each radiation in a spore, the efficiency of producing DNA damage that could cause inactivation, and the repair capacity of each type of spore.     

RADIATION DEGRADATION OF CHITOSAN IN THE PRESENCE OF H2O2

INTRODUCTIONChitosan, poly-β-(1 -?4)-D-glucosamine, can be obtained from chitin by deacetylation with alkali. It is soluble indilute acidic medium due to the presence of amino groups. The use of chitosan in many areas, such as foodprocessing, biochemistry, Pharmaceuticals, medicine, and agriculture has been developed over the pastdecades[1,2].In recent years, it has been reported that many properties of chitosan depend on the molecular weight[3]. Thechitosan oligomers possess better fun…     

ACTION SPECTRA FOR IN ACTIVATION AND MEMBRANE DAMAGE OF Saccharomyces cerevisiae CELLS IRRADIATED IN VACUUM BY MONOCHROMATIC SYNCHROTRON UV RADIATION (155-250 nm)

We investigated the wavelength dependence of inactivation and membrane damage in yeast cells ( Saccharomyces cerevisiae ) in the range from 170 to 200 nm. Action spectra constructed at wavelengths from 155 to 250 nm using published data were nearly the same for the two types of effects below 200 nm, but differed from the absorption spectrum of DNA, indicating that major lethal damage occurred in the membrane, not in DNA. This conclusion was strongly supported by the finding that far-UV-sensitive cells, which lack excision repair, showed no enhanced sensitivity below 200 nm.     

THE RADIATION CROSSLINKING OF EPR/SBR BLEND

The radiation crosslinking of EPR/SBR blend has been studied. A relationship between sol fraction and radiation dose for the different weight ratio polymer blends and the method to calculate βb value of EPR/SBR blend system have been established.     

ACTION SPECTRA IN ULTRAVIOLET WAVELENGTHS (150-250 nm) FOR INACTIVATION AND MUTAGENESIS OF Bacillus subtilis SPORES OBTAINED WITH SYNCHROTRON RADIATION

Bacillus subtilis spores were exposed in vacuo to monochromatic UV radiation from synchrotron radiation in the wavelength range of 150 nm to 250 nm. Survival and frequency of mutation to histidine-independent reversion were analysed for three types of spores differing in DNA-repair capabilities. UVR spores (wild-type DNA repair capability) exhibited nearly equal sensitivity to the lethal effects of far-UV (220 nm and 250 nm) and of vacuum-UV radiation (150 and 165 nm), but showed marked resistance to 190 nm radiation. UVS spores (excision-repair and spore-repair deficient) and UVP spores (a DNA polymerase I-defective derivative of UVS) exhibited similar action spectra; pronounced sensitivity at 250 and 220 nm, insensitivity at 190 nm and a gradual increase of the sensitivity as the wavelength decreased to 165 nm. In all strains, the action spectra for mutation induction paralleled those for the inactivation, indicating that vacuum-UV radiation induced lethal and mutagenic damages in the spore DNA. The insensitivity of the spores to wavelengths around 190 nm may be explicable by assuming that radiation is absorbed by materials surrounding the core in which DNA is situated.     

THE ROLE OF SOLAR ULTRAVIOLET RADIATION IN 'NATURAL' WATER PURIFICATION

Abstract— The concentration of Escherichia coli in the input and output of a tertiary wastewater system (4 lagoons) has been monitored over an 11 month period. The integrated flux of biologically active solar ultraviolet (UV) radiation was measured during this period. By also determining (1) the effective temperature in the system, (2) the growth rate of E. coli at the effective temperature, (3) the penetration of the solar UV into the lagoons, (4) the dose-response relation for killing of E. coli by UV and (5) the retention time of water in the system, it is possible to compare the 'die off' expected from solar UV exposure to the actual 'die off' observed for different batches of water.
The observed killing of E. coli was quite close to the values calculated, considering the numerous factors involved. Solar UV light would thus seem to be a very important factor in the natural purification of water. Because each successful species must possess characteristics (physiological or behavioral) which provide adequate resistance to solar UV, the ecological role of solar UV radiation has not been widely appreciated.