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Nonphotochemical quenching (NPQ) is known to depress in vivo fluorescence (IVF) of chlorophyll a (Chla) in aquatic environments, which makes it difficult to interpret the hour-to-hour variations in Chla measured by in situ fluorometers. We hypothesized that ratios between quenched and unquenched IVF are a function of both NPQ and photochemical quenching. In this study, two diatom model species Thalassiosira pseudonana (CCMP1335) and Thalassiosira weissflogii (CCMP1047) incubated under a sinusoidal light:dark cycle were studied; IVF was recorded continuously, and Chla and photo-physiological variables were measured seven times a day. The maximal decline in Chla-specific IVF (IVF

The Chukchi Sea is the inflow shelf between the Arctic and the Pacific. A comprehensive research on algal dynamics, physical–biological interactions, and impacts on nutrient drawdown was conducted in summer 2010. The study found a phytoplankton bloom with chlorophyll a (Chla) > 10 mg m−3 at ice edge in July. There were 36 shared algal species in both sea ice and open water, and those species dominated numerically both environments highlighting the seeding role of ice algae for the phytoplankton bloom. The succession pattern of diatom genera at three phases from sea-ice to open-water bloom and post-bloom conditions was revealed, and the phytoplankton abundance was positively correlated with the concentration of > 20 µm fractionated Chla. An anticyclonic eddy was detected in July and significantly reduced nutrient inventories in the impacted area relative to historical values. Phytoplankton composition was an important factor for both variable drawdown ratios of silicate to dissolved inorganic nitrogen (1.31–3.37) and dissolved inorganic nitrogen to dissolved inorganic phosphorus (7.62–12.32); however, both ratios also changed between July and August. The results indicated highly dynamic biogeochemical processes during the summer. In addition, the lower bound of silicate drawdown was comparable to the amount imported through the Bering Strait, indicating the Chukchi Sea is a significant silicate sink.

Through photosynthesis, phytoplankton initiate material cycling and the flow of energy through marine ecosystems. The structure of marine ecosystems is sensitive to the size of primary producers, and size-specific photosynthesis-irradiance (P-I) parameters are required for modeling the size-specific primary production. We defined a phytoplankton type to be a group of phytoplankton communities with similar compositions and hypothesized that a function of phytoplankton types might be used to quantify systematic differences of P-I parameters between size classes (structural effects) and variations of the magnitudes of those parameters if the overlap between habitats was small (environmental effects). To test this hypothesis, we conducted a study to measure the size-specific P-I parameters of two size classes ( 2 μm) and pigment-based phytoplankton community structure in a marginal sea, the Taiwan Strait. Three phytoplankton types were classified, and type-based and size-specific P-I parameters were derived. The results demonstrated the potential of a type-based model to estimate P-I parameters for two phytoplankton size classes as well as different habitats.

Oceanic chlorophyll-a concentration (Chl, mg m−3) maps derived from satellite ocean color measurements are the only data source which provides synoptic information of phytoplankton abundance on global scale. However, after excluding data collected under non-optimal observing conditions such as strong sun glint, clouds, thick aerosols, straylight, and large viewing angles, only ~5% of MODIS ocean measurements lead to valid Chl retrievals, regardless of the fact that about 25–30% of the global ocean is cloud free. A recently developed ocean color index (CI) is effective in deriving relative ocean color patterns under most non-optimal observing conditions to improve coverage, but these patterns cannot be interpreted as Chl. In this study, we combine the advantage of the high-quality, low-coverage Chl and lower-quality, higher-coverage CI to improve spatial and temporal coverage of Chl through machine learning, specifically via a random forest based regression ensemble (RFRE) approach. For every MODIS scene, the machine learning requires CI, Rayleigh-corrected reflectance (Rrc (λ = 469, 555, 645 nm), dimensionless), and high-quality low-coverage Chl from the common pixels where they all have valid data to develop an RFRE-based model to convert CI and Rrc (λ) to Chl. The model is then applied to all valid CI pixels of the same scene to derive Chl. This process is repeated for each scene, and the model parameterization is optimized for each scene independently. The approach has been tested for the Yellow Sea and East China Sea (YSECS) where non-optimal observing conditions frequently occur. Validations using extensive field measurements and image-based statistics for 2017 show very promising results, where coverage in the new Chl maps is increased by ~3.5 times without noticeable degradation in quality as compared with the original Chl data products. The improvement in Chl coverage without compromising data quality is not only critical in revealing otherwise unknown bloom patterns, but also important in reducing uncertainties in time-series analysis. Tests of the RFRE approach for several other regions such as the East Caribbean, Arabian Sea, and Gulf of Mexico suggest its general applicability in improving Chl coverage of other regions.

Predicting changes of phytoplankton communities in response to global warming is one of the challenges of ecological forecasting. One of the constraints is the paucity of general principles applicable to community ecology. Based on a synecological analysis of a decadal-scale database, we created a niche habitat classification scheme relating nine phytoplankton groups to fifteen statistically refined realized niches comprised of three niche dimensions: temperature, irradiance, and nitrate concentrations. The niche scheme assigned the nine phytoplankton groups to three types of niches: a cold type, a warm type, and a type associated with high irradiance and high nitrate concentrations. The fact that phytoplankton groups in cold niches were governed by irradiance and those in warm niches by nitrate is consistent with general ecological theories, but the fact that diatoms were the only dominant group in high-irradiance, high-nitrate niches challenges the idea based on autecological studies that diatoms are generally better adapted to low-irradiance, high-nutrient conditions. When combined with an irradiance model, the niche scheme revealed that photoinhibition of Prochlorococcus, which is predicted from autecological studies, is a function of temperature. We used the niche scheme to predict the responses of phytoplankton communities to environmental changes due to seawater warming and eutrophication. The results of the study suggest that a synecological analysis of large databases from field studies facilitates identification of general principles of community ecology that can be used to forecast responses of biological communities to environmental changes.

Increases of atmospheric CO2 concentrations due to human activity and associated effects on aquatic eco- systems are recognized as an environmental issue at a global scale. Growing attention is being paid to CO2 enrichment effects under multiple stresses or fluctuating environmental conditions in order to extrap- olate from laboratory-scale experiments to natural systems. We carried out a mesocosm experiment in coastal water with an assemblage of three model phytoplankton species and their associated bacteria under the influence of elevated CO2 concentrations. Net community production and the metabolic charac- teristics of the phytoplankton and bacteria were monitored to elucidate how these organisms responded to CO2 enrichment during the course of the algal bloom. We found that CO2 enrichment (1000 μatm) signifi- cantly enhanced gross primary production and the ratio of photosynthesis to chlorophyll a by approxi- mately 38% and 39%, respectively, during the early stationary phase of the algal bloom. Although there were few effects on bulk bacterial production, a significant decrease of bulk bacterial respiration (up to 31%) at elevated CO2 resulted in an increase of bacterial growth efficiency. The implication is that an eleva- tion of CO2 concentrations leads to a reduction of bacterial carbon demand and enhances carbon transfer efficiency through the microbial loop, with a greater proportion of fixed carbon being allocated to bacterial biomass and less being lost as CO2. The contemporaneous responses of phytoplankton and bacterial metabolism to CO2 enrichment increased net community production by about 45%, an increase that would have profound implications for the carbon cycle in coastal marine ecosystems.

A basic albeit elusive goal of ocean science is to predict the structure of biological communities from the multitude of environmental conditions they experience. Estimates of the realized niche-based traits (realized traits) of phytoplankton species or functional groups in temperate seas have shown that response traits can help reveal the mechanisms responsible for structuring phytoplankton communities, but such approaches have not been tested in tropical and subtropical marginal seas. Here, we used decadal-scale studies of pigment-based phytoplankton groups and environmental conditions in the South China Sea to test whether realized traits could explain the biogeographic patterns of phytoplankton variability. We estimated the mean and breadth of the phytoplankton realized niches based on responses of the group-specific phytoplankton composition to key environmental factors, and we showed that variations of major phytoplankton groups in this system can be explained by different adaptive trade-offs to constraints imposed by temperature, irradiance, and nutrient concentrations. Differences in the patterns of trade-offs clearly separated the dominant groups from one another and generated four sets of realized traits that mirrored the observed biogeographic distribution patterns. The phytoplankton realized niches and their associated traits that we characterized in the present study could help to predict responses of phytoplankton to changes in environmental conditions in the South China Sea and could be incorporated into global biogeochemical models to anticipate shifts in community structure under future climate scenarios.

Picoeukaryotes play an important role in the biogenic element cycle and energy flow in oligotrophic ecosystems. However, their biodiversity and activity are poorly studied in open ocean systems, such as the northwestern Pacific Ocean, which is characterized by a complex hydrological setting. Here, we investigated the diversity and activity of picoeukaryotes in the northwestern Pacific Ocean using high-throughput sequencing targeting the V9 region of 18S rDNA and rRNA. Our results showed that the DNA picoeukaryotic communities were mainly represented by Mamiellophyceae, MAST, MALV-II, Spirotrichea, Prymnesiophyceae, and MALV-I (69.33% of the total DNA reads), and the RNA communities were dominated by Spirotrichea, Mamiellophyceae, MAST, Pelagophyceae, and MALV-II (67.46% of the total RNA reads). The number of operational taxonomic units (OTUs) was significantly affected by temperature and salinity, and was decreased with the increasing nutrient concentration both in the DNA and RNA surveys. Significant differences were observed in the community composition between DNA-based and RNA-based molecular approaches, and these differences were mainly attributed to Mamiellophyceae, Spirotrichea, and Pelagophyceae. The RNA: DNA ratio was used as a proxy for relative metabolic activity of the individual OTUs. We found that the relative metabolic activities of Mamiellophyceae, Spirotrichea, and Pelagophyceae species in the northwestern Pacific Ocean were highly affected by the nutrient concentration, i.e., the NO3 + NO2 and SiO3 concentration. Overall, our study shed light on picoeukaryotic diversity and distribution in the northwestern Pacific Ocean and revealed the correlation between the diversity, relative metabolic activities of marine picoeukaryotes, and the environmental factors.

Seasonal patterns of phytoplankton biomass and primary production (PP) are important features characterizing a marine ecosystem. The South China Sea (SCS) has been arbitrarily illustrated as an ecosystem with low PP in summer and high PP in winter. However, there is an emerging consensus about a lack of unity of PP seasonality in the SCS even in the northern SCS shelf-sea. Through analysis of the distributions of the remotely sensed colored dissolved organic matter absorption coefficient, a river-dominated ocean margin in the northern SCS (NSCS-RiOMar) with the 50 m isobath as its southeastern boundary has been defined. The difference in PP seasonality between the NSCS-RiOMar and the whole shelf-sea was evaluated by both the measured and the remotely sensed depth-integrated primary production (ΣPP). A diagnostic analysis found that euphotic depth and a function of the half-saturation light intensity accounted for the seasonal variation of ΣPP in the NSCS-RiOMar. Accordingly, the Platt and Sathyendranath (1993) model plus the nearest neighbor method and the semi-analytical estimates of euphotic depth were used to compute the remotely sensed ΣPP. The average ΣPP in the NSCS-RiOMar were 1146.4, 1604.7, 979.5, and 891.3 mg C m−2 d−1 in spring, summer, autumn, and winter, respectively, contrasted with small seasonal variations in the whole shelf-sea. The unimodal ΣPP peak was in June-July in accordance with the peak of Pearl River discharge. This result was striking because previous remote sensing studies all showed the reversed seasonal pattern of ΣPP in both the NSCS-RiOMar and the whole shelf-sea. The annual PP was estimated to be 33.5 ± 2.3 Mt C yr−1 and 56.2 ± 3.2 Mt C yr−1 in the NSCS-RiOMar and the whole shelf-sea, respectively. The nutrients inputted by the China Coastal Current might account for 4–23% of ΣPP in the NSCS-RiOMar between December and February.

This study examines temporal variations of 234Th-based particle export based on time-series observations conducted from 2004 to 2014 at the South-East Asian Time-series Study (SEATS) site in the basin area of the Northern South China Sea. It shows significant variability in particle export at both seasonal and interannual time scales. A significant feature of our data as observed by prior studies is that particle export was high during the NE monsoon in winter, but low during the inter-monsoon and SW monsoon. Particle flux increased with increasing mixed layer depth (MLD), primarily in winter due to the presence of a strong NE monsoon, in addition to influence by mesoscale features quantified by eddy kinetic energy values. Particle export was generally elevated when phytoplankton biomass was abundant, as shown by the significant correlation between particle fluxes and concentrations of chlorophyll (Chl) a and/or particulate organic carbon (POC) between 0 and 100 m. This is also supported by the negative correlation between 234Th residence time and Chl a concentration, suggesting that increased phytoplankton biomass accelerated downward particle sinking. The correlation disappeared however at Chl a values

There is ongoing debate as to whether the oligotrophic ocean is predominantly net autotrophic and acts as a CO2 sink, or net heterotrophic and therefore acts as a CO2 source to the atmosphere. This quantification is challenging, both spatially and temporally, due to the sparseness of measurements. There has been a concerted effort to derive accurate estimates of phytoplankton photosynthesis and primary production from satellite data to fill these gaps; however there have been few satellite estimates of net community production (NCP). In this paper, we compare a number of empirical approaches to estimate NCP from satellite data with in vitro measurements of changes in dissolved O2 concentration at 295 stations in the N and S Atlantic Ocean (including the Antarctic), Greenland and Mediterranean Seas. Algorithms based on power laws between NCP and particulate organic carbon production (POC) derived from 14C uptake tend to overestimate NCP at negative values and underestimate at positive values. An algorithm that includes sea surface temperature (SST) in the power function of NCP and 14C POC has the lowest bias and root-mean square error compared with in vitro measured NCP and is the most accurate algorithm for the Atlantic Ocean. Nearly a 13 year time series of NCP was generated using this algorithm with SeaWiFS data to assess changes over time in different regions and in relation to climate variability. The North Atlantic subtropical and tropical Gyres (NATL) were predominantly net autotrophic from 1998 to 2010 except for boreal autumn/winter, suggesting that the northern hemisphere has remained a net sink for CO2 during this period. The South Atlantic sub-tropical Gyre (SATL) fluctuated from being net autotrophic in austral spring-summer, to net heterotrophic in austral autumn–winter. Recent decadal trends suggest that the SATL is becoming more of a CO2 source. Over the Atlantic basin, the percentage of satellite pixels with negative NCP was 27%, with the largest contributions from the NATL and SATL during boreal and austral autumn–winter, respectively. Variations in NCP in the northern and southern hemispheres were correlated with climate indices. Negative correlations between NCP and the multivariate ENSO index (MEI) occurred in the SATL, which explained up to 60% of the variability in NCP. Similarly there was a negative correlation between NCP and the North Atlantic Oscillation (NAO) in the Southern Sub-Tropical Convergence Zone (SSTC), which explained 90% of the variability. There were also positive correlations with NAO in the Canary Current Coastal Upwelling (CNRY) and Western Tropical Atlantic (WTRA) which explained 80% and 60% of the variability in each province, respectively. MEI and NAO seem to play a role in modifying phases of net autotrophy and heterotrophy in the Atlantic Ocean.

Many recent models for retrieval of primary production in the sea from ocean-color data are temperature based. But previous studies in low latitudes have shown that models that include phytoplankton community structure can have improved predictive capability. In this study, we measured photosynthetic parameters from photosynthesis-irradiance (P-E) experiments, phytoplankton absorption coefficients, and phytoplankton community structure derived from algal pigments during four cruises in the northern South China Sea (NSCS). The maximum quantum yield of CO2 ( ΦmC) and the chlorophyll a-normalized P-E curve light-limited slope (αB) varied significantly with the blue-to-red ratio of phytoplankton absorption peaks (aph(435)/aph(676)) (p

Increases of atmospheric CO

The East China Sea is a productive marginal sea with a wide continental shelf and plays an important role in absorbing atmospheric carbon dioxide and transferring terrigenous organic matter to the open ocean. To investigate the roles of heterotrophic bacteria in the biogeochemical dynamics in the East China Sea, bacterial biomasses (BB) and productions (BP) were measured in four cruises. The spatial distributions of the BB and the BP were highly season-dependent. Affected by the Changjiang River discharge, the BB and the BP were high in shelf waters (bottom depth not deeper than 50 m) and generally decreased offshore in August 2009. In December 2009 to January 2010, and November to December 2010, the BB and the BP were high in waters with medium bottom depth. The onshore-offshore decreasing trends of the BB and the BP also existed in May-June 2011, when the BB was significantly higher than in other cruises in shelf break waters (bottom depth deeper than 50 m but not deeper than 200 m). The results of generalized additive models (GAM) suggest that the BB increased with the temperature at a range of 8-20 degrees C, increased with the chlorophyll concentration at a range of 0.02-3.00 mg/m(3) and then declining, and decreased with the salinity from 28 to 35. The relationship between the temperature and the log-transformed bacterial specific growth rate (SGR) was linear. The estimated temperature coefficient (Q(10)) of the SGR was similar with that of the phytoplankton growth. The SGR also increased with the chlorophyll concentration. The ratio of the bacterial to phytoplankton production ranged from less than 0.01 to 0.40, being significantly higher in November-December 2010 than in May-June 2011. Calculated from the bacterial production and growth efficiency, the bacterial respiration consumed, on average, 59%, 72% and 23% of the primary production in August 2009, November-December 2010, and May-June 2011, respectively.

An efficient tandem method for the annulation of 1-amino-1H-pyrrole-2-amides with various substituted benzaldehydes, heteroaryl aldehydes, alkyl aldehydes or even acetals, promoted by cupric chloride, to synthesize 2-substituted pyrrolo[2,1-f][1,2,4]triazin-4(3H)-ones is reported. This approach provides a useful method for constructing the privileged structure in medicinal chemistry. Electron-donating groups on both partners could accelerate the reaction.

A simple, convenient, and efficient method for the formation of functionalized dibenzo[b,f]oxepins and their analogs bearing both electron-donating and electron-withdrawing groups has been developed via a one-pot cascade reaction. Most starting materials are commercially available 2-(2-hydroxyphenyl)acetonitriles and 2-haloarylaldehydes. The procedure makes use of Cs2CO3 as the base, and DMF as solvent under copper-assisted/copper-free conditions. The reaction has a comprehensive group tolerance for substrates. Most of the reactions were complete within 1 h in good-to-excellent yields, and the reaction temperatures were relatively low. The protocol could be scaled up to grams without lowering the yield. A reaction mechanism was also proposed.

A green and efficient preparation of functionalized δ-carbolines/carbazoles via reductive ring closure by 1,2-bis(dipenylphosphino)ethane under solvent-free conditions is described. The starting materials 3-nitro-2-phenylpyridines/2-nitrobiphenyl derivatives are readily prepared through Suzuki–Miyaura cross-coupling reaction from commercially available compounds. And the polar by-product ethane-1,2-diylbis(diphenylphosphine oxide) is easily removed from the relatively polar reaction mixture. Various substituted δ-carbolines/carbazoles are obtained in acceptable yields. It is particularly worth mentioning that substrates with electron-withdrawing groups (EWG) also give the desired products in good yield.

National Natural Science Foundation of China [40810069004, 40776041, 40676046]; National High Technology Research and Development Program of China [2007AA091704]; New Century Excellent Talents (NCET)

Schiprolactone A, a triterpenoid lactone with a new side chain skeleton was isolated from the stems of Schisandra propinqua together with schisanlactones A and B. Their structures were elucidated by spectral studies.

The selective Suzuki cross-coupling reaction of 4-(5-chloro-8-iodopyrido[4,3-d]pyrimidin-2yl)morpholine and 4-(8-bromo-5-chloropyrido[4,3-d]pyrimidin-2-yl)morpholine catalyzed by palladium has been studied during the preparation of 8-aryl-substituted 4-(5-chloropyrido[4,3d]pydimidin-2-yl)morpholines as key intermediates of potential PI3K inhibitors. This is the first report of the selective Suzuki cross-coupling reaction of fused π-deficient heterocycles containing a 2-chloro-5-halopyridine. The selectivity of the reaction is highly dependent on the nature of the palladium catalyst, solvent, base and temperature. Under optimized conditions, a variety of aryl boronic acids and even heteroaryl boronic acids were coupled in high yield and selectivity.

Various benzo[b][1,8]naphthyridin-2-ones were synthesized by a one-pot tandem reduction-double cyclization from the corresponding (Z)-ethyl 4-cyano-5-(2-nitrophenyl)-pent-4-enoates, which were easily prepared via Johnson-Claisen rearrangement from Baylis-Hillman affixtures of 2-nitrobenzaldehydes. The procedure has the advantages of easy handling and seperation under mild and green conditions, and the overall yields are moderate.

We examined the acute toxicity of depleted uranium (DU) after subcutaneous injection as a simulated wound model (experiment I), and the effects of a chelating agent, catechol-3,6-bis(methyleiminodiacetic acid) (CBMIDA), on the removal and damages caused by uranium by local treatment for wounds in rats (experiment II). Experiment I: To examine the initial behavior and toxicity of uranium of different chemical forms, male Wistar rats were subcutaneously injected with 4 and 16 mg kg-1 DU in a solution of pH 1 and 7. The rats were killed 1, 3, 6, and 24 h after DU injection. The DU (pH 1) injection site on the skin was altered markedly by acid burn, and the chemical action of uranium compared with that of DU (pH 7). After the injection of 4 mg kg-1 DU (pH 1), about 60% of the uranium was retained 1-3 h at the injected sites and then decreased to 16% at 24 h. However, the concentration of uranium in the injected site after 16 mg kg-1 DU (pH 1) injection did not change significantly. Urinary excretion rates of uranium (pH 1) increased in a time-independent manner after the injection. Depositions of uranium in the liver, kidneys and femur were found at 1 h after DU injection, and the results of serum and urinary examinations indicated that severe damage in the organs, including the kidney, was induced. The results of the DU (pH 7) were useful for estimating the chemical toxicity of uranium. Experiment II: The effects of CBMIDA by local treatment for wounds with DU were examined. CBMIDA (480 mg kg-1) was infused into the DU-injected site 0, 10, 30, 60, 120 min, and 24 h after the subcutaneous injection of 4 mg kg-1 DU (pH 1 and 7). The uranium at the injected sites decreased to 4-17% of that at 24 h in the DU (pH 1) group without CBMIDA treatment in experiment I, when it was administered within 120 min after DU injection. In addition, CBMIDA had excellent efficacy in excreting the uranium in urine and feces and decreasing the concentrations of uranium in the kidneys and femur. However, there were no distinct effects of CBMIDA for DU (pH 7). In conclusion, the results indicated that the subcutaneous injected uranium acutely induced severe damage in the DU-injected sites and organs by chemical toxicity within a very short time after DU intake, despite the chemical forms of uranium used, and the local treatment of CBMIDA for wounds contaminated with DU was effective in decreasing the acute toxicity of uranium if carried out within 120 min after DU administration.

The efficacy of oral administration of the chelating agent catechol-3,6-bis(methyleiminodiacetic acid) (CBMIDA) for removing uranium from rats after intraperitoneal (i.p.) and intramuscular (i.m.) injections of depleted uranium (DU) was examined and the results with those by the i.p. injection of CBMIDA were compared. In Experiment 1, after a single i.p. injection of 8 mg kg(-1) of DU of rat's body weight, 35 8-week-old male rats were divided into seven groups consisting of five rats each. Three groups were administered with CBMIDA 240, 720 or 1200 mg kg(-1) of rat's body weight orally once a day, and three other groups received an i.p. injection of 240, 480 or 720 mg kg(-1) CBMIDA for 3 d, starting 30 min after DU injection on the first day. One DU group received no CBMIDA. The remaining five intact rats were used as a control group. Rats were killed 6 d after DU injection. In Experiment 2, the 35 male rats that received a single i.m. injection of 8 mg kg(-1) DU were divided into seven groups, and the rats of each group received the same doses of CBMIDA on the same schedules of treatment as those described in Experiment 1. The results obtained in Experiment 1 indicated that orally administered CBMIDA significantly increased the excretion of uranium at doses of 720 and 1200 mg kg(-1) and decreased uranium concentrations, particularly in the kidney, at all the doses tested, and the effects were almost equal to those of the i.p. injection. The lack of increases in creatinine and blood urea nitrogen in serum indicated that CBMIDA is efficacious in preventing the renal dysfunction caused by uranium. In Experiment 2, oral administration of CBMIDA significantly increased uranium excretion and significantly decreased uranium concentrations, particularly in the kidneys, at all the doses tested, and the effects were almost equal to those of the i.p. injection. However, these effects of CBMIDA on the i.m.-injected DU were lower than those of the i.p.-injected DU in Experiment 1. These results indicated that oral administration of CBMIDA has almost the same efficacy as that administered by the parenteral route. Additional study is necessary to obtain satisfactory effects for the clinical use of CBMIDA, particularly for wounds contaminated accidentally with uranium.

The effects of bicarbonate and its combination with the chelating agents, deferiprone (L1), 4,6-dimethyl-1-hydroxypyrimidin-2(1H)-one (AK-4), catechol-3,6-bis(methyleneimino-diacetic-acid) (CBMIDA), and ethane-1-hydroxy-1,1-bisphoshonate (EHBP) in removing depleted uranium (DU) for radiation emergency medicine were examined. After the intramuscular injection of DU in rats, various time schedules of bicarbonate and chelating agent administration were tested. The results indicate that the bicarbonate helps increase significantly the effects of LI and AK-4, while there were no effects of using bicarbonate alone. The effects of bicarbonate on CBMIDA were unclear, and the effects of EHBP were negative. Further studies are necessary to obtain distinctly synergic effects by the combination of chelating agents with bicarbonate.

A new convenient method for the synthesis of oxazolidinone antibacterials Linezolid and Eperezolid from readily available (S)-glyceraldehyde acetonide was developed. The key steps include reductive amination of arylamine and (S)-glyceraldehyde acetonide in the presence of NaBH4 and 4 A sieve, followed by hydrolysis and regioselective cyclization. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:316–319, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20435

We examined the effects of a diuretic, isotonic saline, and chelating agent, catechol-3, 6-bis (methyleiminodiacetic acid) (CBMIDA), on the excretion and prevention of renal damage of depleted uranium (DU). Male Wistar rats (8 weeks old) divided into seven groups were preinjected intraperitoneally with 4 mg/kg DU and then the six groups were injected intraperitoneally with a diuretic, a diuretic plus isotonic saline, 480 mg/kg or 720 mg/kg CBMIDA alone, or 480 mg/kg or 720 mg/kg CBMIDA plus a diuretic and saline for three days, and the one group was as the control (no treatment). The rats were killed 6 days after DU injection. The results indicated that the diuretic alone and the diuretic with isotonic saline were not effective in removing uranium from the body and protecting the renal function, and also did not help to increase significantly the effects of CBMIDA.

A series of 4,5-disubstitute-1,2,3-thiadiazole compounds were designed and synthesized as potent anticancer agents, some of them exhibited excellent in vitro and in vivo inhibitory activity.

We examined the acute toxicity of uranium (99.3% 2 3 8 U, 0.7% 2 3 5 U) and the effects of Catechol-3,6-bis-(methyleiminodiacetic acid) (CBMIDA) and Ethane-1-hydroxy-1,1-bisphosphonate (EHBP) on the removal of uranium after intramuscular injection as a simulated wound intake in rats. In this experiment, male Wistar rats, 8 wk old, were injected intramuscularly with uranyl nitrate in the femoral muscles. Experiment I: Rats died from 3 to 7 d after they were injected with five doses of 7.9, 15.8, 31.5, 63, and 126 mg kg - 1 uranium. The uranium retained 8.4-13.6% of the injected doses in the kidneys, showing the relationship between the injected dose and the retained concentration (r = 0.997). The excretion rates of the injected doses in the 63 and 126 mg kg - 1 uranium-injected rats were 1.73% and 3.09% in urine and 0.81% and 1.06% in feces on the first day, and 0.54% and 0.56% in feces on the second day, respectively. Experiment II: The retention of uranium at 1, 3, 6, and 24 h was examined after rats were injected with 63 mg kg - 1 uranium. The concentration of uranium decreased in the plasma, while it increased in the kidneys and femur until 6 h, and it continued to increase in the liver until 24 h. Experiment III: Rats were divided into four groups (n = 10) and were injected with a dose of 2 mg kg - 1 uranium. Two of the groups were then injected intraperitoneally with 240 or 480 mg kg - 1 CBMIDA, and one group was injected with 10 mg kg - 1 EHBP once daily for 28 d, beginning 1 h after uranium injection on the first day. The fourth group was the non-treated control group. The survival rates at the end of the experiment were 80% and 40% in the 240 and 480 mg kg - 1 CBMIDA groups, 50% in the EHBP group, and 20% in the non-treated group. The successive administration of chelating agents was effective in decreasing the concentration of uranium in the kidneys, bone, and liver. The results indicated that uranium induces acute death and renal dysfunction by chemical toxicity, and both CBMIDA and EHBP were effective agents to prevent these effects.