Tissue-free water tritium and non-exchangeable organically bound tritium concentrations in fish near coastline during and after operation of Japan's first nuclear fuel reprocessing facility.

The risks from radioactive wastewater release from nuclear facilities into the ocean are a global concern. Radioactive contaminants, such as tritium (3H), in both forms of tissue free water tritium (TFWT) and non-exchangeable organically bound tritium (NE-OBT), can be incorporated into marine biota and cause radiation doses to biota and future consumers. However, no studies have been conducted to measure both forms of 3H in marine fish as well as evaluate the residence time in the vicinity of a nuclear fuel reprocessing facility. Here, fish from a brackish lake and from the Pacific Ocean coastline of Japan, which are near such a facility, were collected between 2006 and 2021. The reprocessing facility was operational between 2006 and 2009, during which time about 300 times more tritiated water was discharged per year into the ocean compared to the period when the facility was not operational. During operation the annual release was 30 times higher than the treated water released annually from Fukushima Daiichi. As expected, TFWT and NE-OBT concentrations increased in marine fish during operations and had peak values of 3.59 ± 0.03 and 0.56 ± 0.03 Bq/L, respectively. Total dose rates to the fish were 36,000 times lower than the 10 µGy h-1 benchmark. Concentrations gradually decreased to pre-operational levels as the facility was turned off with NE-OBT taking twice as long. Fish sampled from the brackish lake tended to have more incorporated TFWT and NE-OBT concentrations than ocean fish. This indicates that ocean tides might have contributed to the accumulation of discharged tritiated water in the lake via a narrow water channel, which highlights the importance of examining all marine ecosystems in future operations. In both marine environments, the estimated committed effective dose using the highest observed data through ingestion was well below public limits (91,000 times lower).

Interlaboratory comparison exercises for organically-bound tritium in the development of reference materials of environmental samples.

The complex behavior of tritium and the probability of increasing tritium concentrations released in the environment were the promotors for the research and development of laboratory methods that enable to accurately determine the various forms of tritium including organically-bound tritium (OBT) for public and regulatory assurance. The measurement of tritium is a key step for dose and risk assessment. The Cernavoda Nuclear Power Plant (NPP) in Romania improved preparation methods and tested environmental matrices for OBT analysis through intercomparison exercises. This paper describes the international Organically-Bound Tritium (OBT) intercomparison exercise, organized by the Cernavoda Nuclear Power Plant (NPP) in 2019-2020, using fruit sample (quince) from Cernavoda town. Evaluation of the results from the participating laboratories was performed using both robust analysis (Algorithm A) method described in the ISO 13528:2015 standard and ANOVA method. The results obtained are encouraging as an increased number of participating laboratories did not change the observed dispersion of the results for activity concentration level around 50 Bq/L of combustion water. The stability of the remaining sample will be checked in time to investigate its use as a reference material for OBT analysis at the environmental levels.

Evaluation of the Hydrophilic, Cohesive, and Physical Properties of Eight Hyaluronic Acid Fillers: Clinical Implications of Gel Differentiation.

Background: Hyaluronic acid (HA) fillers are used to treat an array of aesthetic indications. Proper filler selection is paramount for successful patient outcomes. However, many important physiochemical and physical properties that impact HA gel behavior remain undefined. Purpose: To evaluate the hydrophilicity, cohesivity and particle size of eight commercial HA fillers manufactured by either Non-Animal Stabilized Hyaluronic Acid (NASHA) or Optimal Balance Technology (OBT) techniques. Methods and Materials: Three individual in vitro experiments were performed to assess HA swelling capacity, cohesion, and particle size. Image analyses, blinded evaluation using the Gavard-Sundaram Cohesivity Scale, and laser diffraction technology were utilized, respectively. Results: Compared to fillers manufactured with NASHA technology, OBT products demonstrated greater swelling capacity, cohesion, and wider particle size distributions. Strong positive correlations between swelling factor, degree of cohesivity, and increasing widths of the particle size distributions were observed. Conclusions: The hydrophilicity, cohesivity and particle size distributions vary among HA fillers manufactured with different techniques. The creation of new labels identifying products based on their unique combination of physiochemical and physical characteristics may help guide appropriate selection of HA fillers to optimize patient outcomes.

Influence of irrigation approaches and spatial geolocation on tritium speciation, uptake and depuration.

Pine needles and tree cores from a tritium (T) contaminated phytoremediation forest at the Savannah River Site (SRS in Aiken, SC) Mixed Waste Management Facility (MWMF) were measured for total T and T speciation and compared to other locations at the SRS and the surrounding area. Tree core ages ranged from 9 to 14 years old, covering over half of the ∼20-year on-going remediation efforts, while pine needles represent more recent time periods of 1-to-2-year increments. Remedial irrigation efforts at the MWMF are found to directly influence the pine needle T concentrations. The T content in the MWMF samples is higher than non-irrigated needle samples from other locations around the SRS. Further, the different forms of organic bound T are preferentially stored in tree core tissue, compared to pine needles where tritiated water dominates.

Analysis of environmental biological effects and OBT accumulation potential of microalgae in freshwater systems exposed to tritium pollution.

The ecological risk of tritiated wastewater into the environment has attracted much attention. Assessing the ecological risk of tritium-containing pollution is crucial by studying low-activity tritium exposure's environmental and biological effects on freshwater micro-environment and the enrichment potential of organically bound tritium (OBT) in microalgae and aquatic plants. The impact of tritium-contaminated wastewater on the microenvironment of freshwater systems was analyzed using microcosm experiments to simulate tritium pollution in freshwater systems. Low activity tritium pollution (105 Bq/L) induced differences in microbial abundance, with Proteobacteria, Bacteroidota, and Desulfobacterota occupying important ecological niches in the water system. Low activity tritium (105-107 Bq/L) did not affect the growth of microalgae and aquatic plants, but OBT was significantly enriched in microalgae and two aquatic plants (Pistia stratiotes, Spirodela polyrrhiza), with the enrichment coefficients of 2.08-3.39 and 1.71-2.13, respectively. At the transcriptional level, low-activity tritium (105 Bq/L) has the risk of interfering with gene expression in aquatic plants. Four dominant cyanobacterial strains (Leptolyngbya sp., Synechococcus elongatus, Nostoc sp., and Anabaena sp.) were isolated and demonstrated good environmental adaptability to tritium pollution. Environmental factors can modify the tritium accumulation potential in cyanobacteria and microalgae, theoretically enhancing food chain transfer.

A deuterium tracer experiment for simulating accumulation and elimination of organically bound tritium in an edible flatfish, olive flounder.

Tritium (3H, T) is discharged by nuclear facilities into coastal oceans as tritiated water (HTO). When the concentration of HTO in seawater increases, the accumulation of organically bound tritium (OBT) in edible fish becomes a concern because of its longer residence time than HTO. To evaluate the accumulation potential of OBT in olive flounder (Paralichthys olivaceus), a commercially important edible fish in northeast Asia, we experimentally exposed the fish to seawater enriched with deuterium (2H, D) as a substitute for tritium. Progressive increases and decreases in the concentration of organically bound deuterium (OBD) were observed in the edible part (i.e., muscle) of the fish during the period of exposure to 2H (161 days) and the subsequent period of elimination of OBD (196 days). The measured concentration of OBD was analyzed using a newly developed single-compartment model to describe the metabolism of OBD in muscle via the following three transfer pathways: formation of OBD from 2H in water, elimination of OBD by catabolism, and ingestion of feed with natural abundance of OBD. The model estimates were in good agreement with the measured muscle OBD concentrations. The formation and elimination rate constants for OBD in the muscle were estimated by fitting our model to the measured data. The biological half-life of OBT in the muscle, estimated from the elimination rate constant, was 133 days, which was far longer than that of HTO in the free water of the muscle. Our model facilitates the estimation of OBT accumulation potential in olive flounder inhabiting coastal areas near nuclear facilities, and thus, will help to assess the radiation dose that humans are exposed to from ingesting seafood.

Predictive Cell Culture Time Evolution Based on Electric Models.

Obtaining cell concentration measurements from a culture assay by using bioimpedance is a very useful method that can be used to translate impedances to cell concentration values. The purpose of this study was to find a method to obtain the cell concentration values of a given cell culture assay in real time by using an oscillator as the measurement circuit. From a basic cell-electrode model, enhanced models of a cell culture immersed in a saline solution (culture medium) were derived. These models were used as part of a fitting routine to estimate the cell concentration in a cell culture in real time by using the oscillation frequency and amplitude delivered by the measurement circuits proposed by previous authors. Using real experimental data (the frequency and amplitude of oscillations) that were obtained by connecting the cell culture to an oscillator as the load, the fitting routine was simulated, and real-time data of the cell concentration were obtained. These results were compared to concentration data that were obtained by using traditional optical methods for counting. In addition, the error that we obtained was divided and analyzed in two parts: the first part of the experiment (when the few cells were adapting to the culture medium) and the second part of the experiment (when the cells exponentially grew until they completely covered the well). Low error values were obtained during the growth phase of the cell culture (the relevant phase); therefore, the results obtained were considered promising and show that the fitting routine is valid and that the cell concentration can be measured in real time by using an oscillator.

Assessing OBT formation and enrichment: ROS signaling is involved in the radiation hormesis induced by tritium exposure in algae.

Tritium is the main component of radioactive wastewater from nuclear power plants and can be migrated into organisms to form organically bound tritium (OBT), which may pose a potential risk to aquatic ecosystem. Hence, it is essential to monitor OBT conversion in the presence of tritium exposure. In this study, the effects of pretreatment methods such as digestion on the recovery of tritium were discussed. It was found that microwave digestion pretreatment could improve the recovery of tritium by up to 90 % and allow OBT measurement with a small sample size equivalent to about 60 mg (dry weight). In addition, the efficiency of OBT transformation was different among biological samples, and the radiation hormesis phenomenon was induced by tritium exposure (3.7 × 106 Bq/L) in microalgae Chlorella vulgaris（C. vulgaris）. The tritium exposure may induce radiation hormesis through the reactive oxygen species (ROS) signaling pathway, thus improving the photosynthetic capacity and metabolism level of C. vulgaris. Furthermore, enhancement of photorespiration metabolism and the antioxidation system may be important means for C. vulgaris to balance damage by tritium radiation. This study provides insights for further investigating OBT behavior, and will contribute to understanding the equilibrium damage mechanism of algae exposed to tritium.

Annual variation of different forms of tritium in the soil around Qinshan Nuclear Power Plant.

Tritium deposited in soil forms HTO and OBT. To further understand the changes of HTO and OBT in different years, HTO and OBT in the soil around Qinshan Nuclear Power Base in different sampling years were measured. According to the annual distribution of HTO and OBT in the surface soil, it could be inferred whether there was a long-term release of tritium in the observed year. From the depth distribution of different years, OBT tends to migrate to the deep. From 2015 to 2020, the correlation analysis between OBT and HTO/soil organic matter showed that HTO contributed more to OBT in surface soil at 250-2000 µm and 53-250 µm particle sizes, but this conclusion did not apply to deep soil. However, there was no significant relationship between OBT activity and soil organic matter content.

Investigation of ratio of carbon to hydrogen (C/H ratio) in agricultural plants for further estimation of their productivity of organically bound tritium.

The carbon to hydrogen ratio (C/H ratio, w/w) in plants is a key factor in estimating the amount of hydrogen in the photosynthetic product. The amount of hydrogen calculated from photosynthetic model estimation associated with the C/H ratio is an essential parameter of the estimation model of productivity of organically bound tritium (OBT) by plants. To propose a sophisticated estimation model of OBT by agricultural plants, temporal changes in the C/H ratio of six plant species (Japanese radish, cabbage, orchard grass, paddy field rice, apple, and radish) during their cultivation were investigated for each plant part. The C/H ratio in the plants cultivated in the field and growth chamber generally exceeded 6, which is the value for the primary photosynthetic monosaccharides, such as glucose and fructose (both chemical formulae, C6H12O6). In the vegetative parts (e.g. Japanese radish leaves, cabbage leaves and roots, rice leaves and roots, and radish leaves and fine roots) the C/H ratio fluctuated irregularly or remained constant within an approximate range of 6.6-7.3 during cultivation. The C/H ratio in enlarged organs (e.g. Japanese radish root, rice ear, apple fruit, and radish main root) decreased continuously, approaching 6. These results suggest that the C/H ratio can be generally set as approximately 6.9 except for enlarged organs, in which the ratio may change over time during cultivation, within an approximate range of 6-7.

A bone paradigm challenging the standard model of myeloma oncogenesis.

The standard model of multiple myeloma (MM) oncogenesis from monoclonal gammopathy of undetermined significance (MGUS) relies on genetic instability in the normal counterparts of MM cells. However, the importance of both MGUS-associated and MM-induced bone changes has been recently re-appraised, emphasizing the bone microenvironment (BME) as a tissue of significance. In this review, we propose that early BME alterations (bone senescence and inflammation, i.e., bone inflamm'aging) at the pre-MGUS stage could be causal, and not simply permissive, and creative of phenotypic instability and genetic alterations thanks to the concept of tissue disruption-induced cell stochasticity (TiDiS). This article offers a bone scenario challenging the chromosome-and-gene-centric standard model of MM oncogenesis. The high incidence of both MGUS and MM in Gaucher disease supports such a scenario.

Determination of the baseline tritium concentrations (HTO, TFWT and OBT) in soil and plants in Ontario, Canada.

Tritiated water (HTO), tissue free water tritium (TFWT) and organically bound tritium (OBT) activity concentrations in soil and plant leaves, collected at background areas in Ontario, were measured to quantify the current tritium baseline. Five representative background sites, based on their geological characteristics and residential populations, have been selected for this study. Undisturbed soils, plant leaves and surface water samples were collected at 5 sites (London, Kapuskasing, Thunder Bay, Elliot Lake and Cornwall areas) in 2015. Water sample HTO activity concentrations were measured using Liquid Scintillation Counting (LSC, ALOKA), and HTO activity concentrations for soil and TFWT for plant leaves were measured by LSC (Quantulus 1220) on water extracted from frozen samples using a freeze-drying vacuum system equipped with a liquid nitrogen trap. Plant leaf OBT levels were obtained by combustion of rinsed freeze-dried samples using a Parr combustion system, while soil OBT values were obtained using a tube furnace combustion system. Combustion water was distilled before being counted by LSC (Quantulus 1220). HTO activity concentrations were found to range between 1.4 and 2.0 Bq/L (MDA = 0.5 Bq/L) in surface water and soil samples. TFWT values were less than the minimum detectable activity (MDA = 3.5 Bq/L) in plant leaves. In contrast, OBT activity concentrations (MDA = 5 Bq/L) ranged from 5.7 to 17.1 Bq/L in plant leaves and 8.3-20.7 Bq/L in surface soil (0-5 cm depth). The overall OBT activity concentrations were higher in the London and the Cornwall areas. Lower levels were measured near Thunder Bay, Kapuskasing and Elliot Lake. There was no obvious relationship between soil OBT activity concentrations and soil types. The results provide the current tritium (HTO, TFWT and OBT) baseline values in Ontario. These values will be helpful for use as background locations for the evaluation of past and future environmental tritium inputs associated with nuclear facilities, and will be taken into account when evaluating the environmental impact of nuclear facilities in Ontario. Since samples in this study were primarily taken in wooded areas, some questions remain regarding the possibility that soil samples in open, non-wooded areas could show different HTO and OBT contents than those presented in this study.

Assessment of the tritium distribution in the vegetation cover in the areas of underground nuclear explosions at the Semipalatinsk test site.

This paper provides results of assessment of the tritium distribution in the vegetation cover in the areas of underground nuclear explosions at the Semipalatinsk Test Site (STS). The research was conducted at the former "Degelen" test site along the streams that are one of the main channels of tritium migration from underground nuclear explosions epicenters. The dominant plant species Carex supine and Achnatherum splendens that belong to different ecological groups in relation to humidity were selected as representatives of the vegetation cover. The TFWT (tissue free water tritium) and OBT (organically bound tritium) activity concentrations in the vegetation cover were measurement. TFWT activity concentration in the samples of both plant species had high values with an average of up to 30 kBq kg-1. The OBT activity concentration was 1-2 orders of magnitude lower than the TFWT in all plant samples. The TFWT and OBT activity concentrations in vegetation samples are closely correlated (r = 0.75, p < 0.05). No statistically significant difference was found between the content of tritium in the samples of Carex supine and those of Achnatherum splendens taken at the same locations. OBT/HTO ratios for vegetation samples of both species were close to equilibrium ratio used in environmental transfer models. In some cases, OBT/HTO ratios were significantly lower than one, which indicates that simple environmental transfer models may not accurately predict the behavior of HTO and OBT in different environmental compartments. The average OBT/HTO ratio for soil samples (0.6 ± 0.1) close to the equilibrium value indicates the equilibrium condition at the research area. The obtained [OBT]plant/[OBT]soil ratios indicate that soil organic matter accumulates tritium from year to year. However, in some locations with high tritium contamination ratios [OBT]plant/[OBT]soil were more than one due to OBT activity in soils is almost the same as OBT activity in plants. It was found that the nature of the spatial distribution of tritium in the vegetation cover in the areas of underground nuclear explosions is complex, and obviously depends on the location of the tunnels in which nuclear tests were conducted, as well as on the peculiarities of the hydrological regime of underground and surface waters, which are the main channels of tritium migration in the research area. Thus, the vegetation cover reflects the spatial distribution of tritium contamination in the sites of underground nuclear explosions and can be used as an indicator of the radiation situation when monitoring radiation-hazardous areas.

Tritium distribution in typical plants around tritium laboratory in south-west of China.

A low-temperature desorption method was developed to remove the tissue free water tritium (TFWT) in plants, which dramatically reduces the sample-preparation time from several days to only 2-3 h. Two factors, including spatial distribution and seasonal variation, that influence the tritium distribution and the organic bound tritium (OBT)/TFWT ratios in plants were investigated based on three different kinds of subtropical-basin plants located near the decommissioned nuclear facility in south-west of China. Under the same environmental condition, higher tritium concentration was seen in pine needle (PN) compared with flat bamboo-root (FBT) and wild cotton (WC), while these three plants show similar location- and season-dependent trend of tritium distribution. The location-dependent investigation shows that OBT and TFWT concentration are significantly higher in plants growing in the downwind direction of the tritium laboratory than that in plants growing in the upwind and cross direction. In different seasons, the TFWT in plants reached peak in winter and valley in summer, while the OBT increased continuously with the season changing from spring to winter. The ratios of OBT/TFWT were investigated to evaluate the ability of plants to concentrate tritium into organic matter, which were 0.97-2.72 for PN, 0.89-1.64 for FBR, and 0.80-1.62 for WC.

A computer-aided design tool for biomedical OBT sensor tuning in cell-culture assays.

BACKGROUND AND OBJECTIVES: The biomedical engineering must frequently develop sensor designs by including information from performance of bio-samples (cell cultures or tissues), technical specifications of transducers, and constrains from electronic circuits. A computer program for real-time cell culture monitoring system design is developed; analyzing, modelling and integrating into the program design flow the electrodes, cell culture and test circuit's influences. METHODS: The computer tool, first, generates an equivalent electric circuit model for the cell-electrode bio-systems based on the area covered by cells, which also considers the cell culture dynamics. Second, proposes an Oscillation Based Test (OBT) parameterized circuit, for Electrical Cell-Substrate Sensing (ECIS) measurements of the cell culture system bioimpedance. Third, simulates electrically the full system to define the best system parameter values for the sensor. RESULTS: Reported experimental results are based on commercial gold electrodes and the AA8 cell line. Characteristics of the cell lines, as time-division or cell size, are incorporated into the program design flow, showing that for a given assay, the optimal OBT circuit parameters can be selected with the help of the computer tool. The electrical simulations of the full system demonstrate that the can be correctly predicted the output frequency and amplitude ranges of the voltage response, obtaining accurate results when cell culture approaches to confluence phase. CONCLUSION: It is proposed a computer program for system design of biosensors applied to monitoring cell culture dynamics. The program allows obtaining confident system information by electrical stimulation. All system components (electrodes, cell culture and test circuits) are properly modelled. The employed procedure can be applied to any other 2D electrode layout or alternative circuit technique for ECIS test. Finally, deep insight information on cell size, number, and time-division can be extracted from the comparison with real cell culture assays in the future.

Distribution of tritium concentration in the 0-25 cm surface soil of cultivated and uncultivated soil around the Qinshan nuclear power plant in China.

In this study, tritiated water (HTO) and organically bound tritium (OBT) activity concentration at different depth soil layers (0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, and 20-25 cm) were measured in uncultivated and cultivated soil samples collected in the vicinity of the Qinshan nuclear power plant (QNPP) in July, September, and December 2018. The concentration difference, the spatial and temporal distribution, the seasonal variation, and the OBT/HTO ratios were investigated. The average ratios of HTO concentration between uncultivated and cultivated soil moisture were 1.20 ± 0.24, 1.39 ± 0.46 and 0.95 ± 0.14 in July, September and December, respectively, the corresponding values for OBT were 1.17 ± 0.31, 1.22 ± 0.49 and 1.08 ± 0.28. In generally, the highest HTO concentration in uncultivated soil was found for the topsoil (0-5 cm) in July and September and for the deeper soil layer (20-25 cm) in December, while for cultivated soil, the highest levels were found for the middle layer soil in July, for the topsoil (0-5 cm) in September, and for the deeper layer soil (20-25 cm) in December. Both soils, the vertical profile distribution of OBT concentration showed no consistent tendency, and there were no significant differences in the HTO and OBT concentrations between different soil layers, except for the highest concentration. Whether uncultivated soil or cultivated soil, HTO activity concentrations showed an apparent spatial distribution and seasonal variability, decreasing with the distance to the release sources and with sampling time, while OBT concentrations showed lower spatial and seasonal variability than HTO. In most cases, the OBT/HTO ratios were less than 1, with average values of 1.01 ± 0.48 and 1.06 ± 0.86 for cultivated soil and cultivated soil samples, respectively. The results of this work suggest that farming may affect tritium behavior in soil, while the spatial and temporal distribution of tritium is only slightly impacted.

CD157: From Myeloid Cell Differentiation Marker to Therapeutic Target in Acute Myeloid Leukemia.

: Human CD157/BST-1 and CD38 are dual receptor-enzymes derived by gene duplication that belong to the ADP ribosyl cyclase gene family. First identified over 30 years ago as Mo5 myeloid differentiation antigen and 10 years later as Bone Marrow Stromal Cell Antigen 1 (BST-1), CD157 proved not to be restricted to the myeloid compartment and to have a diversified functional repertoire ranging from immunity to cancer and metabolism. Despite being a NAD+-metabolizing ectoenzyme anchored to the cell surface through a glycosylphosphatidylinositol moiety, the functional significance of human CD157 as an enzyme remains unclear, while its receptor role emerged from its discovery and has been clearly delineated with the identification of its high affinity binding to fibronectin. The aim of this review is to provide an overview of the immunoregulatory functions of human CD157/BST-1 in physiological and pathological conditions. We then focus on CD157 expression in hematological tumors highlighting its emerging role in the interaction between acute myeloid leukemia and extracellular matrix proteins and its potential utility for monoclonal antibody targeted therapy in this disease.

Organically bound tritium (OBT) activity concentrations in surface soil at the Chalk River Laboratories, Canada.

Canadian Nuclear Laboratories (CNL)'s Chalk River Laboratories (CRL) site is home to a large nuclear research complex in Canada. CRL's air tritium releases amount to about 1015 Bq/year. The objective of the study was to characterize the spatial footprint of the 60 years of tritium atmospheric releases in surface soil by measurement of organically bound tritium (OBT). Soil OBT activity concentrations were of particular interest because soil represents a long-term tritium reservoir that can act as a historical record of tritium releases into the environment. Soil samples to a 5 cm depth were collected within the CRL site from 2012 to 2014. Each sample was analyzed for tritiated water (HTO) and OBT activity concentrations. The highest HTO and OBT measurements obtained during this study were 154.0 ±â€¯7.8 Bq/L and 180.9 ±â€¯37.3 Bq/L, respectively. A developed OBT map indicated that retained tritium in soil was not related to the distance of sources-term but it was related to the prevailing wind direction.

Thiamine and benfotiamine protect neuroblastoma cells against paraquat and ß-amyloid toxicity by a coenzyme-independent mechanism.

BACKGROUND: Benfotiamine (BFT) is a synthetic thiamine precursor with high bioavailability. It is efficient in treating complications of type 2 diabetes and has beneficial effects in mouse models of neurodegenerative diseases. The mechanism of action of BFT remains unknown, though it is sometimes suggested that it may be linked to increased thiamine diphosphate (ThDP) coenzyme function. METHODS: We used a mouse neuroblastoma cell line (Neuro2a) grown in thiamine-restricted medium. The cells were stressed by exposure to paraquat (PQ) or amyloid ß1-42 peptide in the presence or absence of BFT and the cell survival was measured using the MTT method. In each case, BFT was compared with sulbutiamine (SuBT), an unrelated thiamine precursor, and thiamine. Metabolites of BFT were determined by HPLC and mass spectrometry. RESULTS: At 50 µM, BFT protects the cells against PQ and amyloid ß1-42 peptide-induced toxicity with the same efficacy. Protective effects were also observed with SuBT and with higher concentrations of thiamine. The main metabolites of BFT were thiamine and S-benzoylthiamine (S-BT). Treatment with both precursors induces a strong increase in intracellular content of thiamine. Protective effects of BFT and SuBT are directly related to thiamine (but not ThDP) levels in Neuro2a cells. CONCLUSIONS: BFT, SuBT and thiamine all protect the cells against oxidative stress, suggesting an antioxidant effect of thiamine. Our results are not in favor of a direct ROS scavenging effect of thiamine but rather an indirect effect possibly mediated by some antioxidant signaling pathway. It is however not clear whether this effect is due to thiamine itself, its thiol form or an unknown metabolite. GENERAL SIGNIFICANCE: Our results suggest a role of thiamine in protection against oxidative stress, independent of the coenzyme function of thiamine diphosphate.

Distribution of organically bound tritium (OBT) activity concentrations in aquatic biota from eastern Canada.

A survey of eastern Canadian biota was conducted to determine the distribution of activity concentrations of organically bound tritium (OBT). Fish samples were collected from Lake Ontario and the St. Lawrence River in areas continuously receiving inputs of tritiated water (HTO) from operating nuclear power plants, and from Lake Nipissing, a background area. Components of their aquatic environments were sampled. The data collected also provides some insight on how tritium activity concentrations in ambient water influence tissue free water tritium (TFWT) and OBT activity concentrations in biological tissues. Using an ALOKA liquid scintillation system, fish TFWT and OBT were quantified. Fish TFWT averaged 1.6 ±â€¯0.1 Bq/L in Lake Nipissing and 3.1 ±â€¯0.3 Bq/L in Lake Ontario. In contrast, TFWT ranged from 11.1 to 80.8 Bq/L in the St. Lawrence River near the Gentilly-2 Canada Deuterium Uranium (CANDU) site. Fish tissue OBT levels were 4.0 ±â€¯0.4 Bq/L and 5.3 ±â€¯0.2 Bq/L for Lake Nipissing and Lake Ontario, respectively, and between 18.1 and 134.2 Bq/L for CANDU sites. The activity concentrations of TFWT and OBT were reviewed for algae, freshwater mussel and various fish samples collected near Gentilly-2, Pickering and Darlington Nuclear Power Generating Stations. TFWT in aquatic biota was found to correlate with the tritium activity concentrations measured in waters at the time of sampling (TFWT/HTO of ambient water was 0.3-4.3). The OBT concentration factors (OBT/HTO of ambient water) were found to be higher in freshwater mussels (between 17 and 47) compared to algae and fish (0.3-10). These results point to a heterogeneous distribution of biota OBT content in these aquatic ecosystems. It was also noted that all fish and algae samples were found to be within the range of tritium activity concentrations that has been historically measured in the same waters. Values in freshwater mussels were above this range.