Indicator Of Radiation Damage Research Articles

Yeast Metabolic Response as an Indicator of Radiation Damage in Biological Tissue

AbstractWearable radiation sensors for workers of radiation‐intensive industries provide a measure of radiation exposure but not of its effects on biological tissue. A biohybrid radiation sensing platform based on a new transduction mechanism for detecting biological radiation damage using the metabolic activity of a microorganism population is presented here. The sensor is a wearable, disposable, film‐type device fabricated on a paper substrate with yeast (Saccharomyces cerevisiae) cells patterned between two electrodes and used as a smart material. The device is sensitive to radiation when dry and is read by activating it with water. Yeast (S. cerevisiae) cells, that are exposed to ionizing radiation and subsequently allowed to ferment a glucose solution, exhibit an electrical conductivity that is lower than that of nonexposed yeast. The radiation damage to this microorganism is directly proportional to the measured impedance of the fermenting medium. An 18 × 18 mm2 and 0.57 mm thick sensors with ground yeast (3.09 mg cm−2 areal density filtered with a 50 µm mesh) shows a sensitivity of 4.5% Ω/Ω0decade‐rad upon exposure to Cs‐137. The minimum detectable dose (resolution) is 1 mrad. Fluorescence microscopy results suggest that it is primarily due to damaged membranes in the cell wall and mitochondria.

Radiation damage in protein crystallography at X-ray free-electron lasers

Radiation damage is still the most limiting factor in obtaining high-resolution structures of macromolecules in crystallographic experiments at synchrotrons. With the advent of X-ray free-electron lasers (XFELs) that produce ultrashort and highly intense X-ray pulses, it became possible to outrun most of the radiation-damage processes occurring in the sample during exposure to XFEL radiation. Although this is generally the case, several experimental and theoretical studies have indicated that structures from XFELs may not always be radiation-damage free. This is especially true when higher intensity pulses are used and protein molecules that contain heavy elements in their structures are studied. Here, the radiation-damage mechanisms that occur in samples exposed to XFEL pulses are summarized, results that show indications of radiation damage are reviewed and methods that can partially overcome it are discussed.

Indications of radiation damage in ferredoxin microcrystals using high-intensity X-FEL beams.

Proteins that contain metal cofactors are expected to be highly radiation sensitive since the degree of X-ray absorption correlates with the presence of high-atomic-number elements and X-ray energy. To explore the effects of local damage in serial femtosecond crystallography (SFX), Clostridium ferredoxin was used as a model system. The protein contains two [4Fe-4S] clusters that serve as sensitive probes for radiation-induced electronic and structural changes. High-dose room-temperature SFX datasets were collected at the Linac Coherent Light Source of ferredoxin microcrystals. Difference electron density maps calculated from high-dose SFX and synchrotron data show peaks at the iron positions of the clusters, indicative of decrease of atomic scattering factors due to ionization. The electron density of the two [4Fe-4S] clusters differs in the FEL data, but not in the synchrotron data. Since the clusters differ in their detailed architecture, this observation is suggestive of an influence of the molecular bonding and geometry on the atomic displacement dynamics following initial photoionization. The experiments are complemented by plasma code calculations.

SU-FF-T-170: Dosimetric Characterization of a 2D Diode Array Detector in Passive Scattering Proton Beams

Purpose: To evaluate the dosimetric properties of a two‐dimensional (2D) diode array detector in passive‐scattered proton beams (PSPBs). Materials and Methods: The diode array detector, MapCHECK™, was characterized for PSPBs. The relative sensitivity of diodes and absolute dosecalibration were determined using a 250 MeV beam. The measured pristine Bragg curves (PBCs) by MapCHECK™ were compared with the results of an ion chamber (IC) using a range shift method. The water‐equivalent thickness (WET) of MapCHECK™ buildup was also determined. The inverse square dependence, linearity, and other protondosimetric quantities measured by MapCHECK™ were also compared with IC. The change of absolute dose response of MapCHECK™ as a function of accumulated dose was used as an indicator of radiation damage. 2D dose distribution with and without compensator were measured and compared with treatment planning system (TPS) results. To facilitate the comparison, in‐house software called MU Scaler, was developed. Results: The measured PBCs by MapCHECK™ are virtually identical to those measured by IC for 160, 180, and 250 MeV proton beams. The WET of MapCHECK™ buildup is determined to be 1.7 cm. The inverse square result of MapCHECK™ is the same as the IC results, within ±0.4%. The linearity of MapCHECK™ is within 1% compared to IC data for MUs larger than 10. All other dosimetric quantities are within 1.3% of IC results. The absolute dose response of MapCHECK™ has been changed by 7.4% after accumulating total dose of 170 Gy. Good results are observed for 2D dose distribution for patient treatment fields with and without compensator when compared with TPS results. Conclusions: MapCHECK™ is a convenient and useful tool for 2D dose distribution measurements of PSPBs. Variation of dose response of MapCHECK™ with total accumulated dose should be carefully monitored.

Maximum-likelihood techniques for joint segmentation-classification of multispectral chromosome images

Traditional chromosome imaging has been limited to grayscale images, but recently a 5-fluorophore combinatorial labeling technique (M-FISH) was developed wherein each class of chromosomes binds with a different combination of fluorophores. This results in a multispectral image, where each class of chromosomes has distinct spectral components. In this paper, we develop new methods for automatic chromosome identification by exploiting the multispectral information in M-FISH chromosome images and by jointly performing chromosome segmentation and classification. We (1) develop a maximum-likelihood hypothesis test that uses multispectral information, together with conventional criteria, to select the best segmentation possibility; (2) use this likelihood function to combine chromosome segmentation and classification into a robust chromosome identification system; and (3) show that the proposed likelihood function can also be used as a reliable indicator of errors in segmentation, errors in classification, and chromosome anomalies, which can be indicators of radiation damage, cancer, and a wide variety of inherited diseases. We show that the proposed multispectral joint segmentation-classification method outperforms past grayscale segmentation methods when decomposing touching chromosomes. We also show that it outperforms past M-FISH classification techniques that do not use segmentation information.

Structural and trace element changes in scalp hair of radiographers

Scalp hair samples were collected from medical radiographers and nonradiographers of matching age groups. Structural morphology of hair was studied by scanning electron microscopy, and the trace element profiles in hair were measured using neutron activation analysis. The structural damage to the hair follicles of the radiographers was quite obvious, and this may be a good qualitative indicator of radiation damage at low doses. The concentrations of aluminum (Al), potassium (K), and vanadium (V) in hair of the radiographers were significantly higher, whereas those of antimony (Sb) and magnesium (Mg) were significantly lower than those of nonradiographers. Some of our findings were quite consistent with those of others in determining the changes in trace element concentrations in irradiated tissue.

Micronuclei in human peripheral blood lymphocytes: biological indicator of radiation damage

Micronuclei in human peripheral blood lymphocytes: biological indicator of radiation damage

Characterization through a Data Display of the Different Cellular Responses in X-Irradiated Small Intestine.

Previous work on small intestinal radiation injury has reported changes in epithelial and non-epithelial tissues, but with few quantitative comparisons of different responses by individual cell types. The approach used here quantifies the responses of mouse duodenum to X-irradiation with 6 Gy, 10 Gy and 20 Gy, sampled three days after treatment, and 10 Gy sampled 6 hours, 1 day and 3 days after treatment. Tissue area measurements and counts per circumference for 13 different structural elements are subjected to statistical tests. New data reported here for X-irradiation include the fact that cryptal cells do not respond uniformly, indicating that the crypt/microcolony cannot always be used as a standard unit in assessing radiation injury. Non-epithelial structures, such as submucosal arterioles, are also affected. The data display also includes control-referenced ratios, from which are calculated Tissue Indices and a final Morphological Index, which estimates total structural damage. The Indices are useful in drawing attention to unexpected changes in extent or range of data sets. In addition, the Epithelial Index appears to be a sensitive indicator of radiation damage, even at low doses and early time points. The data display includes a graph of the total Indices and summary tables of data, and encourages close study of the constituent data points.

Operating CMOS after a Si-MBE process: a precondition for future three-dimensional circuits

Complete CMOS integrated circuits grown by Si molecular beam epitaxy (MBE) are discussed. The morphology of the MBE films and the electrical performance of the CMOS transistors were investigated. The CMOS time-keeping circuits work after an MBE process. Indications of radiation damage (threshold shift up to 200 mV) induced by the Si electron-beam evaporator at epitaxial temperatures of 550 degrees C are observed. These are completely gone at 750 degrees C, at which temperature virtually no effect of the MBE process on the CMOS characteristics could be determined. The observed compatibility of Si-MBE with CMOS ICs is an important prerequisite for the monolithic integration of Si-based devices with the complexity level provided by MOS technologies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Urinary excretion of cyclic nucleotides, creatinine prostaglandin E2 and thromboxane B2 from mice exposed to whole-body irradiation from an enhanced neutron field.

Urine volume and excretion of cyclic AMP, cyclic GMP, prostaglandin E2 (PGE2), thromboxane B2 (TxB2) and creatinine were evaluated as potential indicators of radiation damage in mice given 2-5 Gy to the whole body from an enhanced neutron field. In general, urinary cyclic AMP, cyclic GMP, creatinine and urine volumes were positively correlated across time postexposure, for each radiation dose. TxB2 levels positively correlated with urine volume and cyclic AMP excretion only in animals given 2.0 Gy. None of these parameters suggests their use as a prognostic indicator of the extent of radiation damage. Urinary excretion of PGE2 was negatively correlated with other urinary parameters. Biphasic increases in urinary PGE2 were also observed. The initial transient elevation 2-3 days postexposure was not correlated with the dose (2-5 Gy). The second elevation of PGE2 excretion occurred at 6-10 days. The magnitude of the latter increase suggests that urinary PGE2 excretion may be a useful indicator of whole-body or kidney exposure to neutron fields.

Serum Alkaline Phosphatases as Indicators of Radiation Damage in Rats

The effects of whole-body, single-dose irradiations (100, 300, 500, 800 R /sup 60/Co ..gamma.. rays) on the activities of isoenzymes of alkaline phosphatase in the serum of rats have been studied. The degree of changes in the intestinal and liver isoenzyme activity was directly dependent on the radiation dose. A marked, time-dependent decrease in the bone isoenzyme activity in serum was found only after 800 R. A computer processing of biochemical data by stepwise discriminant analysis enabled an early diagnosis of postradiation injury of the gut and bone and to classify the irradiated rats according to the radiation dose (biological dosimeter).

A pattern classification system for the identification of irradiated chromosomes.

Monitoring health-related radiation damage is important for the future, and a system to detect chromosomal aberrations associated with radiation is extremely useful for monitoring populations exposed to radiation. In general, the most useful indicator of radiation damage at the cellular level is the occurrence of ring, dicentric, fragment, and fragment ring chromosomes.

Effects of radiation from 14CO2 absorbed by Pinus strobus L. seedlings during photosynthesis on their subsequent growth and metabolism.

Several times during the year, white pine seedlings were placed in a closed system and each plant was permitted to photo-assimilate 400–500 μCi of 14CO2. At various periods of time after photo-assimilation, the fresh weight, apparent photosynthesis, dark respiration, and distribution of absorbed 14C throughout the seedlings were determined. The location and magnitude of depressed growth caused by the radiation from the incorporated 14C varied with the time of year when photo-assimilation occurred.When 14CO2 photo-assimilation occurred in May and June, suppression of growth was the greatest in the new shoots, whereas when photo-assimilation occurred in the fall, the suppression of growth was more pronounced in the roots. Seedlings which photo-assimilated 14CO2 in the fall appeared normal during winter but their buds failed to develop into new shoots the following spring.It is also suggested that a decrease in the rate of apparent photosynthesis may be used as an indicator of radiation damage brought about by the incorporated 14CO2.

Biochemical Indicators of Radiation Damage

Biochemical Indicators of Radiation Damage

Radiative recombination in germanium as an indicator of radiation damage

It is shown that the radiative recombination of electron-hole pairs from a semiconductor can be used as a monitor of minority-carrier lifetime. By observing the change in the radiative signal under electron-bombardment from n- and p-type germanium for a wide range of majority carrier concentrations, it is shown that a single type of recombination center can account for the minority-carrier lifetime. This level is located at either 0·21 eV from the conduction band or 0·28 eV from the valence band, and has a capture probability for minority holes 24 times that for minority electrons. This technique can be used for the study of radiation damage in other semiconductors where electron-hole radiative recombination has been observed. A prime attribute of the method is that changes in minority-carrier lifetime can be detected in material whose initial lifetime can be of the order of 10 −10 sec.

Modes of Radiation Death in the Chick Embryo: II. A Model of Lethal Mechanisms

Among 6-day chick embryos, the mortallty observed witbin 12 days after an acutely lethal irradiation with Co/sup 60/ gamma rays was partitioned iato groups of 0 to 1 day, 2 to 6 days, and 6 to 1.2 days. A statistical analysis revealed that dose, exposure tisae, and mortality could be simply related within each postirradiation time period. Statistical results together with the pathology observed in decedents suggested the following characterization as a possible model of the mechanisms that influence significantly the acute radiation syndrome: (1) Radiation effects which initiate an injury that leads to mortality in the first period are reversed at a constant rate. Vascular collapse was observed as the dominant pathology among decedents of this period. (2) Mortalities occurring in the second period reflect lethal injuries that are sustained via either a reversible or an irreversible process or both. Fluid imbalance describes grossly the pathological expressions of sustained lethal injury. (3) Hepatic lesions and hematopoietic failure are typical indicators of radiation damage among decedents of the third period. Radiation effects that produce an insult that is lethal in this period are irreversible. An alternate model that postulates a single precursory mechanism on which the injury process of themore » first period and the reversible process of the second period depend is summarized. For the embryo and young chick, the reversal processes of the first period are descriptively and pathologically similar.« less

The Effect of Bone Marrow Injection on the Incorporation of Formate-Carbon-14 into Deoxyribonucleic Acid Purines in X-Irradiated Rats

The establishment of the protective effect of intraperitoneal implants of spleen (1), of intraperitoneal or intravenous injection of spleen homogenates (2, 3), and of the administration of bone marrow suspensions (4-6) on otherwise lethally X-irradiated animals has stimulated interest in the mechanisms by which these preparations modify the lethal effect of X-radiation. Among early indications of radiation damage is the inhibition of incorporation of labeled precursor substances into tissue deoxyribonucleic acids (DNA) in Xirradiated laboratory animals. This effect was first demonstrated by Hevesy et al. (7, 8) with inorganic P32 and acetate-C14. An X-radiation dose of 800 r decreases also the incorporation of glycine-C14 into DNA and ribonucleic acid purines of rabbit bone marrow and of rat intestine (9). Previous studies in this laboratory have shown that protection against radiation death in mice (LD,oo dose) afforded by isologous spleen homogenate injection is accompanied by a reversal of radiationinduced inhibition of incorporation of C'4-formate into spleen and bone marrow nucleic acid purines (10) and by a recovery in the spleen DNA levels (11). The present experiments were designed to determine whether modification of radiation injury in rats by rat bone marrow (6) is similarly reflected in changes in nucleic acid metabolism in radiosensitive tissues. Specifically, the effect of injection of rat bone marrow on the incorporation of formate-C14 into DNA adenine and guanine has been studied in selected tissues of lethally X-irradiated rats.