Dose profiles for lung and breast regions at prospective and retrospective CT coronary angiography using optically stimulated luminescence dosimeters on a 64-detector CT scanner

PurposeThe purpose of our study was to acquire dose profiles at critical organs of lung and breast regions using optically stimulated luminescence (OSL) dosimeters; assess the actual radiation dose delivered at retrospective and prospective computed tomography coronary angiography (CTCA).Materials and methodsUsing a chest CT phantom we applied a prospectively-gated step-and-shoot- and a retrospectively-gated helical mode on a 64-detector row CT scanner. Retrospective scan mode was used with and without electrocardiogram (ECG) based tube current modulation. OSL dosimeters were used to measure dose profiles. In the both scan modes we acquired dose profiles and determined the mean and maximum dose in left lung and in left breast regions.ResultsIn prospective mode, the mean dose was 21.53 mGy in left lung- and 23.59 mGy in left breast region. With respect to the retrospective mode, the mean dose with tube current modulation was 38.63 mGy for left lung- and 46.02 mGy for left breast region, i.e. 0.56 and 0.55 times lower than the mean dose without modulation.ConclusionThe OSL dosimeter is useful for measurement of the actual radiation dose along z-axis at lung and breast regions in the prospective and the retrospective CTCA.     

Advances in optically stimulated luminescence dating of individual grains of quartz from archeological deposits

Paleoanthropologists and archeologists interested in occupation histories, faunal remains, and objects of material culture have become increasingly reliant on optically stimulated luminescence (OSL) dating to construct Quaternary chronologies. In part, the increased use of OSL dating reflects its capacity to date events beyond the range of radiocarbon dating and in contexts where suitable organic materials are absent. An earlier review in Evolutionary Anthropology by Feathers 1 provides a general account of the principles of luminescence dating. Since then, however, important advances have been made in OSL dating of quartz, so that it is now possible to date individual sand‐sized grains and thereby resolve issues of postdepositional mixing of archeological sediments. In this review, we discuss the most important of these advances and their implications with regard to improved age control of archeological sites. We cover aspects of instrumental and methodological development that have facilitated the widespread measurement of single grains related to archeological questions and illustrate our review with some examples of where archeological problems have been resolved using single‐grain OSL dating. We do not propose single‐grain dating as a panacea, because there are instances where it is not straightforward to use or the results may be difficult to interpret; dating in such contexts remains the subject of continuing research.     

Sensitivity and stability of optically stimulated luminescence dosimeters with filled deep electron/hole traps under pre-irradiation and bleaching conditions

PurposeWe aimed to evaluate the characteristics of optically stimulated luminescence dosimeters (OSLDs) with fully filled deep electron/hole traps, and determine the optimal bleaching conditions for these OSLDs to minimize the changes in dose sensitivity or linearity according to the accumulated dose.MethodsInLight nanoDots were used as OSLDs. The OSLDs were first pre-irradiated at a dose greater than 5 kGy to fill the deep electron and hole traps, and then bleached (OSLD_full). OSLD_full characteristics were investigated in terms of the full bleaching, fading, regeneration of luminescence, dose linearity, and dose sensitivity with various bleaching conditions. For comparison, OSLDs with un-filled deep electron/hole traps (OSLD_empty) were investigated in the same manner.ResultsThe fading for OSLD_full exhibited stable signals after 10 min, for 1 and 10 Gy. The mean supra-linear index values for OSLD_full were 1.001 ± 0.001 for doses from 2 to 10 Gy. Small variations in dose sensitivity were obtained for OSLD_full within standard deviations of 0.85% and 0.71%, whereas those of OSLD_empty decreased by 2.3% and 4.2% per 10 Gy for unfiltered and filtered bleaching devices, respectively.ConclusionsUnder the bleaching conditions determined in this study, clinical dosimetry with OSLD_full is highly stable, minimizing the changes in dose sensitivity or linearity for the clinical dose.     

Household salt for retrospective dose assessments using OSL: signal integrity and its dependence on containment,sample collection,and signal readout

The aim of this work was to determine how a latent optically stimulated luminescence (OSL) signal in irradiated household salt is preserved under various ambient conditions, from the time of exposure to the time of signal readout. The following parameters were examined: optical fading in fluorescent light and under darkroom conditions (red light), thermal stability of the OSL signal during storage in a light-tight container, optical fading in representative container types, and sensitization effects of the OSL signal in exposed household salt. Furthermore, the influence of grain mixing within the saltshaker or salt container was studied by determining the dose gradient within typical salt packages. Finally, the signal integrity of salt irradiated under field conditions in a village in Belarus contaminated by Chernobyl fallout was investigated. The results show that the OSL signal in household salt is preserved in large cardboard box containers, but not in white plastic salt containers or in small portion bags used in, e.g., fast food restaurants. Furthermore, the continuous wave blue OSL signal in household salt does not fade significantly during storage up to 140 days. On the contrary, the signal appears to slowly increase during storage (“inverse fading”). Field tests of two different salt containers (with and without black tape to block light) located in Belarussian households confirmed that the signal is preserved in white plastic salt containers when they are covered with extra light-shielding material.     

Time-resolved luminescence energy transfer immunobinding study using a ruthenium-ligand complex as a donor label

A novel immunosystem is described that exploits the effect of luminescence energy transfer from a luminescently labeled antigen to a fluorescent antibody. A luminescent ruthenium-ligand complex (D-455) with absorption/emission maxima at 456/639 nm, respectively, was employed as the donor label, and a squaraine-type cyanine label (636/655 nm), as the fluorescent acceptor label. Specifically, the system human serum albumin (HSA)/anti-HSA was studied. HSA was labeled with the donor dye D-455, and anti-HSA was labeled with the acceptor dye A-631. On formation of the antigen-antibody complex, energy transfer occurs. The radiationless energy transfer affects both the decay time of D-455 and the intensities of the emissions of both D-455 and A-631. The decay time of around 500 ns of D-455 allows frequency-domain measurements in the low kilohertz range and therefore can be based on the use of conventional optoelectronics. This also suggests gated measurements to be performed. The major difference from existing HSA immunosystems is the use of a slow decaying ruthenium-ligand complex as the donor and of a long-wave emitting cyanine acceptor dye having a high quantum yield and a decay kinetics that is governed by the rate of energy transfer from the slow decaying donor.     

The photoprotein pholasin as a luminescence substrate for detection of superoxide anion radicals and myeloperoxidase activity in stimulated neutrophils

Pholasin, the photoprotein of the common piddock Pholas dactylus, emits an intense luminescence upon oxidation. The contribution of superoxide anion radicals and myeloperoxidase (MPO) to Pholasin luminescence in stimulated neutrophils was investigated. Data on Pholasin luminescence were compared with results of superoxide anion radical generation detected by the cytochrome c test as well as with the release of elastase and MPO. In N-formyl-methionyl-leucyl-phenylalanine (fMLP) stimulated neutrophils, most of the luminescence is caused by superoxide anion radicals, whereas MPO shows only a small effect as shown by coincubation with superoxide dismutase (SOD) as well as potassium cyanide (KCN), an inhibitor of MPO. However, both, O₂^- and MPO contribute to light emission in fMLP/cytochalasin B and phorbol myristoyl acetate (PMA) stimulated cells. Thus, the kinetics of O₂^- generation and MPO release can be very well detected by Pholasin luminescence in stimulated neutrophils.

Degranulation of azurophilic granules was assessed using an ELISA test kit for released MPO or detection of elastase activity with MeO-Suc-Ala-Ala-Pro-Val-p-nitroanilide in the supernatant of stimulated cells. Both approaches revealed concurrently similar results concerning the amount and kinetics of enzyme release with data of Pholasin luminescence. Both, cytochrome c measurements and Pholasin luminescence indicate that fMLP/cytochalasin B and PMA stimulated neutrophils produce more O₂^- than fMLP stimulated cells. Thus, Pholasin luminescence can be used to detect, sensitively and specifically, O₂^- production and MPO release from stimulated neutrophils.     

The photoprotein pholasin as a luminescence substrate for detection of superoxide anion radicals and myeloperoxidase activity in stimulated neutrophils

Pholasin, the photoprotein of the common piddock Pholas dactylus, emits an intense luminescence upon oxidation. The contribution of superoxide anion radicals and myeloperoxidase (MPO) to Pholasin luminescence in stimulated neutrophils was investigated. Data on Pholasin luminescence were compared with results of superoxide anion radical generation detected by the cytochrome c test as well as with the release of elastase and MPO. In N-formyl-methionyl-leucyl-phenylalanine (fMLP) stimulated neutrophils, most of the luminescence is caused by superoxide anion radicals, whereas MPO shows only a small effect as shown by coincubation with superoxide dismutase (SOD) as well as potassium cyanide (KCN), an inhibitor of MPO. However, both, O₂^- and MPO contribute to light emission in fMLP/cytochalasin B and phorbol myristoyl acetate (PMA) stimulated cells. Thus, the kinetics of O₂^- generation and MPO release can be very well detected by Pholasin luminescence in stimulated neutrophils.

Degranulation of azurophilic granules was assessed using an ELISA test kit for released MPO or detection of elastase activity with MeO-Suc-Ala-Ala-Pro-Val-p-nitroanilide in the supernatant of stimulated cells. Both approaches revealed concurrently similar results concerning the amount and kinetics of enzyme release with data of Pholasin luminescence. Both, cytochrome c measurements and Pholasin luminescence indicate that fMLP/cytochalasin B and PMA stimulated neutrophils produce more O₂^- than fMLP stimulated cells. Thus, Pholasin luminescence can be used to detect, sensitively and specifically, O₂^- production and MPO release from stimulated neutrophils.     

New ages for Middle and Later Stone Age deposits at Mumba rockshelter, Tanzania: optically stimulated luminescence dating of quartz and feldspar grains

The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and report new ages obtained from optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) measurements on single grains of quartz and multi-grain aliquots of potassium (K) feldspar from the MSA and LSA deposits. Measurements of single grains of quartz allowed the rejection of unrepresentative grains and the application of appropriate statistical models to obtain the most reliable age estimates, while measurements of K-feldspars allowed the chronology to be extended to older deposits. The seven quartz ages and four K-feldspar ages provide improved temporal constraints on the archaeological sequence at Mumba. The deposits associated with the latest Kisele Industry (Bed VI-A) and the earliest Mumba Industry (Bed V) are dated to 63.4 ± 5.7 and 56.9 ± 4.8 ka (thousands of years ago), respectively, thus constraining the time of transition between these two archaeological phases to ∼60 ka. An age of 49.1 ± 4.3 ka has been obtained for the latest deposits associated with the Mumba Industry, which show no evidence for post-depositional mixing and contain ostrich eggshell (OES) beads and abundant microlithics. The Nasera Industry deposits (Bed III) contain large quantities of OES beads and date to 36.8 ± 3.4 ka. We compare the luminescence ages with the previous chronologies for Mumba, and briefly discuss how the revised chronology fits in the context of existing archaeological records and palaeoclimatic reconstructions for East Africa.     

Biocompatible hydroxyapatite nanoparticles as a redox luminescence switch

Abstract  

A redox luminescence switch was prepared by doping hydroxyapatite nanoparticles with CePO₄:Tb. The resulting multifunctional material exhibits good biocompatibility, biological affinity, and potential drug-carrying capability. The luminescent hydroxyapatite nanoparticles may find important applications in biomedical diagnostics, drug delivery, and biological sensors.     

Tetrazolium salt as a seed germination indicator

A preliminary assessment of 2:3:5-triphenyl tetrazolium chloride as a seed germination indicator has been made by testing wheat, barley, oats, peas and vetches. Results as reliable as actual germination tests have been obtained, and the optimum conditions for testing have been determined. The application of this technique to other seeds is also discussed.     

Synthesis of optically active olivil type of lignan from L-arabinose using threo-selective aldol condensation as a key reaction

The threo-selective aldol condensation of (3R, 4S)-3-hydroxy-5-trityloxy-4-pentanolide, which was prepared from L-arabinose, with piperonal was applied to the stereoselective synthesis of the olivil type of lignan, (2R, 3R, 4R)-4-benzyl-4-hydroxy-3-hydroxymethyl-2-(3,4-methylenedioxyphenyl)tetrahydrofuran.     

Construction of a reagentless glucose biosensor using molecular exciton luminescence

Fluorescent protein biosensors, which exhibit a significant change in fluorescence based on the physical interaction between protein and ligand, may prove to be effective tools to measure a variety of analytes. In particular, real-time monitoring of glucose levels has potential applications in bioprocess monitoring and in minimizing health complications caused by diabetes. In this work, site-directed mutagenesis of the Escherichia coli glucose/galactose binding protein (GGBP) was used to engineer double-cysteine mutations that allowed selective covalent attachment of thiol-reactive dyes. Because GGBP undergoes a large conformational change on the addition of glucose, rational placement of these sites allowed glucose-dependent spatial realignment of the two fluorophores, which was monitored as a change in fluorescence intensity and extinction coefficients. Using targeted mutagenesis of the GGBP binding pocket, glucose biosensors were created to measure concentrations spanning five orders of magnitude (0.04-12,000 microM). The glucose biosensor retained its function in complex solutions that contained realistic concentrations of protein and potential interfering agents found in blood serum. In addition to the development of a fluorescent protein sensor for glucose, this work helps to expand the spectroscopic tools used for the detection of conformational movements within a single polypeptide chain.     

Biotechnological approach of improving plant salt tolerance using antioxidants as markers

Salt stress causes multifarious adverse effects in plants. Of them, production of reactive oxygen species (ROS) is a common phenomenon. These ROS are highly reactive because they can interact with a number of cellular molecules and metabolites thereby leading to a number of destructive processes causing cellular damage. Plants possess to a variable extent antioxidant metabolites, enzymes and non-enzymes, that have the ability to detoxify ROS. In the present review, the emphasis of discussion has been on understanding the role of different antioxidants in plants defense against oxidative stress caused by salt stress. The role of different antioxidants as potential selection criteria for improving plant salt tolerance has been critically discussed. With the advances in molecular biology and availability of advanced genetic tools considerable progress has been made in the past two decades in improving salt-induced oxidative stress tolerance in plants by developing transgenic lines with altered levels of antioxidants of different crops. The potential of this approach in counteracting stress-induced oxidative stress has been discussed at length in this review.     

Quinolinium salt as a potent inhibitor of lymphocyte apoptosis

The synthesis of several quinolinium salts and related compounds and their ability to inhibit glucocorticoid-induced apoptosis in murine thymocytes are described. Interestingly, 1-[2-methoxyimino-2-(4-pyrrolidin-1-yl-phenyl)ethyl]quinolinium bromide (11) showed a potent protective effect with an EC(50) of 0.013 microM, which was at least 300-fold more potent than the reference compound pifithrin-alpha.     

Construction of cloning vectors using the Vibrio harveyi luminescence genes luxA and luxB as markers

A synthetic oligodeoxyribonucleotide harboring four new restriction sites was inserted into the luxB gene of Vibrio harveyi. This insertion did not disrupt the reading frame. An active beta-subunit was synthesized since a plasmid with both the luxA and mutated luxB genes conferred upon Escherichia coli the bacterial luciferase (Lux) phenotype in the presence of an aldehyde. Ligation of a piece of foreign DNA at these new cloning sites in the vector extinguish the Lux phenotype of the transformed bacteria. Therefore, the plasmid was used as a cloning vector, and recombinant DNA-containing bacteria were detected by the loss of bioluminescence. To create more versatile plasmids, the intergenic region of phage f1 was inserted outside of the lux genes. The selection by loss of bioluminescence presents several advantages over the white/blue selection of the lacZ gene on indicator plates.     

A homogeneous DNA hybridization system by using a new luminescence terbium chelate

Homogeneous DNA hybridization assay based on the luminescence resonance energy transfer (LRET) from a new luminescence terbium chelate, N,N,N(1),N(1)-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-phenylpyridine]tetrakis(acetic acid) (BPTA)-Tb(3+) (lambda(ex) = 325 nm and lambda(em) = 545 nm) to an organic dye, Cy3 (lambda(ex) = 548 nm and lambda(em) = 565 nm), has been developed. In the system, two DNA probes whose sequences are complementary to the two different consecutive sequences of a target DNA are used; one of the probes is labeled with the Tb(3+) chelate at the 3'-end, and the other is with Cy3 at the 5'-end. Labeling of the Tb(3+) chelate is accomplished via the linkage of a biotin-labeled DNA probe with the Tb(3+) chelate-labeled streptavidin. Strong sensitized emission of Cy3 was observed upon excitation of the Tb(3+) chelate at 325 nm, when the two probe DNAs were hybridized with the target DNA. The sensitivity of the assay was very high compared with those of the previous homogeneous-format assays using the conventional organic dyes; the detection limit of the present assay is about 30 pM of the target DNA strand.     

Delayed luminescence of air-dry soybean seeds as a measure of their viability

Delayed luminescence (DL) excited by visible light has been observed in air-dry seeds of various plants. Changes in seeds of soybeans ( Glycine max L. W.) which occur during natural and accelerated aging were reflected in subsequent loss of vigor and DL increase. The increase of the luminescence is caused by the changes in seed biopolymers, leading to a decrease in their ability to take up water. The method makes it possible to measure DL from a single seed. With aging, the DL was shifted toward higher intensities and there was greater variability. By monitoring the DL of seeds it may be possible to evaluate their quality and storage capability.     

Household chagasic endemia detected as a consequence of a case of congenital infection]

During a study on prevalence of parasitic and viral serological markers in pregnant adolescents, a 17-year-old primipara from Polpaico, village near Santiago, gave birth to a normal male newborn in a Santiago hospital. As both of them presented positive an indirect hemagglutination test (IHAT) for Chagas' disease and the corresponding xenodiagnosis (XD), the infection in the infant was considered to be acquired through the placental route. According to recent epidemiological surveys Polpaico is an endemo-enzootic chagasic rural settlement, where 14.7% of dwellings were infested with Triatoma infestans, while triatominae, persons and domestic mammals were found infected with Trypanosoma cruzi. One month later the adolescent mother, her son and other 11 consanguineous members of the family were visited in their homes in order to submit each of them to a physical examination and to IHAT for Chagas' disease, and XD to those whose IHAT resulted positive. Thus, in 7 (53.8%) the IHAT was positive and in 4 (57.1%) out of these 7 presented positive the XD, results that as a whole yielded a household chagasic endemics.