Fluorescent Oligonucleotides Can Serve As Suitable Alternatives to Radiolabeled Oligonucleotides

Prolonged exposure to radiation from radionuclei used in medical research can cause DNA damage and mutation, which lead to several diseases including cancer. Radioactivity-based experiments are expensive and associated with specialized training, dedication of instruments, approvals, and cleanup with potential hazardous waste. The objective of this study was to find an alternative to the use of radioactivity in medical research using nucleic acid chemistry. FITC-labeled oligonucleotides that contain wild-type (wt) and modified base (8-oxo-G) at the same position and their complementary unlabeled strand were synthesized. Purified DNA repair enzyme, OGG1, and nuclear lysates from MCF-7 breast cancer cells were incubated with double-stranded FITC-labeled wt and 8-oxo-G oligonucleotide to demonstrate the OGG1 incision assay. We found that FITC-coupled oligonucleotides do not impose a steric hindrance during duplex formation, and the fluorescence intensity of the oligonucleotide is comparable with the intensity of the radioactive oligonucleotide. Moreover, we have seen that the OGG1 incision assay can be performed using these fluorescence oligonucleotides, replacing conventional use of radiolabeled oligonucleotides in the assay. Although the use of fluorescent-labeled oligonucleotides was described in detail for incision assays, the technique can be applied to replace a broad range of experiments, where radioactive oligonucleotides are used, eliminating the hazardous consequences of radiation.     

^125I-PLGA标记物的制备与鉴定

目的开发一种^125I-PLGA标记物合成的新技术,并对新合成标记物的性质进行鉴定。方法在密闭容器中,应用重复加热的方法,使Na^125I与PLGA氯仿溶液反应,实施PLGA的^125I放射性标记。并对^125I-PLGA标记物的放射性活度进行检测。结果经过上述标记过程,成功合成了^125I-PLGA标记物,此标记物释放γ射线,放射性活度和材料质量成正比。结论^125I-PLGA标记物与传统的放射性核素标记物相比,具有合成工艺简单、放射性污染易于控制、放射性活度易于检测等优点。     

Human Health Damages due to Indoor Sources of Organic Compounds and Radioactivity in Life Cycle Impact Assessment of Dwellings - Part 1: Characterisation Factors (8 pp)

- Part 1: Characterisation factors (DOI: http://dx.doi.org/10.1065/lca2004.12.194.1) Part 2: Damage scores (DOI: http://dx.doi.org/10.1065/lca2004.12.194.2) - Preamble. In this series of two papers, a methodology to calculate damages to human health caused by indoor emissions from building materials is presented and applied. Part 1 presents the theoretical foundation of the indoor emission methodology developed, as well as characterisation factors calculated for 36 organic compounds, radon and gamma radiation. Part 2 calculates damage scores of building materials with the characterisation factors presented in part 1. The relevancy of including indoor air emission in the full damage scores at a material level and a dwelling level is also quantified and discussed. Goal, Scope and Background Methodologies based on life cycle assessment have been developed to calculate the environmental impact of dwellings. Human health damage due to exposure to substances emitted to indoor air are not included in these methodologies. In order to compare this damage with human health damages associated with the rest of the life cycle of the dwelling, a methodology has been developed to calculate damages to human health caused by pollutants emitted from building materials. Methods Fate, exposure and health effects are addressed in the calculation procedure. The methodology is suitable for organic substances, radon and elements emitting gamma radiation. The (Dutch reference) dwelling used in the calculation was divided in three compartments: crawl space, first floor and second floor. Fate factors have been calculated based on indoor and outdoor intake fractions, dose conversion factors or extrapolation from measurements. Effect factors have been calculated based on unit risk factors, (extrapolated) effect doses or linear relationship between dose and cancer cases. Damage factors are based on disability adjusted life years (DALYs). Results and Discussion Characterisation factors have been calculated for 36 organic compounds, radon and gamma radiation emitted by building materials applied in a Dutch reference dwelling. For organic compounds and radon, the characterisation factors of emissions to the second floor are 10–20% higher than the characterisation factors of emissions to the first floor. For the first and second floor, the characterisation factors are dominated by damage to human health as a result of indoor exposure. The relative contribution of carcinogenic and non-carcinogenic effects to the characterisation factors is generally within one order of magnitude, and up to three orders of magnitude for formaldehyde. Conclusion Health effects due to indoor exposure to pollutants emitted from building materials appear to be dominant in the characterisation factors over outdoor exposure to such pollutants. The health effects of emissions of organic compounds and gamma radiation in the crawl space are very small compared to the health effects of emissions into the other compartments. Using the characterisation factors calculated in this study, it is possible to calculate the human health damage due to emissions of substances and radiation emitted to indoor air and compare this damage with damages to human health associated with the rest of the life cycle of the material. This is the subject of part II of this research.     

The synthesis of a radioactive cytokinin with high specific activity

6-benzylaminopurine-[p-¹H-benzyl] at a specific activity of 10 Ci/mmol was synthesized by reacting p-bromo-6-benzylaminopurine with carrier-free tritium gas in the presence of 10% Pd/C. A radiochemical purity of 97% was obtained by a one-step purification of the tritiated reaction product using cellulose TLC. This simple procedure yields the highly active cytokinin, 6-benzylaminopurine, with tritium at near maximum specific activity in a known, stable position.     

Regular measurement: A new method of biophysical experiment

A system of quantized relations between the value of the parameter (quantity) measured and the range of its experimental scattering has been revealed by analyzing the results of experiments on measuring the rates of various processes. Especially long series of stereotyped measurements under stable conditions (called regular measurements) are performed for determining the squared ratio of the standard deviation to the mean value of the quantity measured (D). Regular measurements of biochemical, chemical, and physical parameters show that the D value is related to the universal dimensionless constant D ₀, whose numerical value has been determined with considerable accuracy, and this relation is described by a simple rational equation. The simplicity of the relationship between D and D ₀ may be accounted for by the quantum behavior of the macroinstrument-object system manifested in the course of regular measurement.     

Anther‐smut fungi from more contaminated sites in Chernobyl show lower infection ability and lower viability following experimental irradiation

The long‐term contamination that followed the nuclear disaster at Chernobyl provides a case study for the effects of chronic ionizing radiation on living organisms and on their ability to tolerate or evolve resistance to such radiation. Previously, we studied the fertility and viability of early developmental stages of a castrating plant pathogen, the anther‐smut fungus Microbotryum lychnidis‐dioicae, isolated from field sites varying over 700‐fold in degree of radioactive contamination. Neither the budding rate of haploid spores following meiosis nor the karyotype structure varied with increasing radiation levels at sampling sites. Here, we assessed the ability of the same M. lychnidis‐dioicae strains to perform their whole life cycle, up to the production of symptoms in the plants, that is, the development of anthers full of fungal spores; we also assessed their viability under experimental radiation. Fungal strains from more contaminated sites had no lower spore numbers in anthers or viability, but infected host plants less well, indicating lower overall fitness due to radioactivity exposure. These findings improve our understanding of the previous field data, in which the anther‐smut disease prevalence on Silene latifolia plants caused by M. lychnidis‐dioicae was lower at more contaminated sites. Although the fungus showed relatively high resistance to experimental radiation, we found no evidence that increased resistance to radiation has evolved in populations from contaminated sites. Fungal strains from more contaminated sites even tolerated or repaired damage from a brief acute exposure to γ radiation less well than those from non‐ or less contaminated sites. Our results more generally concur with previous studies in showing that the fitness of living organisms is affected by radiation after nuclear disasters, but that they do not rapidly evolve higher tolerance.     

Henri Becquerel’s discovery of radioactivity – 125 years later

This year it is 125 years since Henri Becquerel accidentally discovered radioactivity. It has been argued that this was the result after Becquerel’s long, systematic research into the phenomenon of luminescence. Becquerel’s discovery, together with Marie and Pierre Curie’s discovery of radium, became the breakthrough for the 20th century research in medical radiation physics and the use of radioactivity in medicine. In this paper, we draw attention to Becquerel’s discovery and the impact it had on medicine and society.     

Luminescence dating and modern human origins

For the most recent evolutionary history of our species, that covering the emergence of anatomically modern humans during the last 100,000 years or more, few dating methods have such a wide range of potential application as luminescence dating. With its ability to provide direct ages in this time range for both archeological and depositional events, and using commonly occurring materials, luminescence seems to be an appropriate tool for almost any location containing modern or near-modern human fossils or artifacts. However, the method is complicated and expensive, depending on variables that may be difficult to estimate in any given situation. This has deterred widespread use, although recent methodological developments have increased accuracy and reliability. An understanding of the potential and limitations of luminescence dating should help students of human origins judge its value and evaluate its applications.     

Automated scanning of 14C on polyacrylamide gel.

Cylindrical polyacrylamide gels were automatically analyzed for radioactive 14C using a commercially available radiochromatogram scanner. This method was capable of detecting peaks of [14C]protein containing 50 000--1 000 000 cpm. Under optimal conditions, gels could be scanned at a rate of 1 cm per min, allowing for analysis of 20--30 gels per day.