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Wen-xiong Wang - One of the best experts on this subject based on the ideXlab platform.
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Arsenic biokinetics and bioavailability in deposit-feeding clams and polychaetes.
The Science of the total environment, 2018Co-Authors: Wei Zhang, Wen-xiong WangAbstract:Abstract In the present study, the arsenic (As) biokinetics and bioavailability in two deposit-feeding invertebRates (clams Gafrarium tumidum and polychaetes Nereis succinea) were quantified. Radiotracer techniques were applied to measure the dissolved uptake Rate, dietary assimilation efficiency and Efflux of As by the clams and polychaetes. Simultaneously, arsenic species analysis was conducted to examine the As biotransformation following dietary uptake. The radiotracer results showed that the uptake Rate Constant and Efflux Rate Constant were 0.068 L/g/d and 0.07 d− 1, and 0.173 L/g/d and 0.09 d− 1, in the clams and polychaetes, respectively. Sediments labeled for different times (1.5–60 d) with different inorganic/organic As percentages led to diverse assimilation efficiencies of As (35.1–56.1% in the clams, and 51.6–72.6% in the polychaetes). Modeling calculations showed that sediment was a significant source for As bioaccumulation in the two deposit-feeders. After feeding on the spiked sediments, inorganic As (75.6%) was initially the predominant form, but arsenobetaine (AsB) became the predominant compound (> 90%) in the clams and polychaetes during depuration, suggesting biotransformation of inorganic As. Combined with the biokinetics and biotransformation measurements, we showed that AsB was more efficiently assimilated and tended to be accumulated, whereas As(III) was less efficiently assimilated and more rapidly eliminated by the two invertebRates. This study demonstRated that As speciation in the sediments as a significant source for As bioaccumulation caused different bioavailability in deposit-feeding clams and polychaetes.
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Interspecies differences in calcium content and requirement in four freshwater cladocerans explained by biokinetic parameters
Limnology and Oceanography, 2010Co-Authors: Qiao-guo Tan, Wen-xiong WangAbstract:We tested the hypothesis that cladocerans with higher calcium (Ca) content are more susceptible to Ca limitation by conducting life table experiments using four cladoceran species with contrasting Ca contents (0.06– 2.24% of dry weight). Populations of Daphnia carinata and Daphnia galeata with high Ca content might collapse when the ambient Ca concentration is , 0.5 mg L21, whereas Ceriodaphnia dubia, with intermediate Ca content, and Moina macrocopa, with low Ca content, are well adapted to that low Ca level. However, Ca content is not a good proxy of the susceptibilities to Ca limitation within the genus of Daphnia. We propose an index, which considers both the Ca demand (i.e., Ca content under Ca-sufficient conditions) and the ability of cladocerans to extract and retain Ca in low-Ca environments, to explain the differences in cladoceran tolerances to Ca deficiency. We also used physiologically based biokinetic parameters, including the influx Rate and Efflux Rate Constant of Ca, to predict the interspecies differences of specific Ca content. Low-Ca species had a lower influx Rate and a higher Efflux Rate Constant of Ca than the high-Ca species. A Ca concentration of 2 mg L21 was sufficient to keep
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Copper uptake kinetics and regulation in a marine fish after waterborne copper acclimation.
Aquatic toxicology (Amsterdam Netherlands), 2009Co-Authors: Fei Dang, Huan Zhong, Wen-xiong WangAbstract:Abstract The uptake kinetics and regulation of copper in a marine predatory fish, the black sea bream Acanthopagrus schlegeli after acclimation to waterborne Cu were examined, using radiotracer techniques. The dissolved Cu uptake followed a linear pattern during the time of exposure, and the calculated uptake Rate Constant was 6.24 L kg −1 day −1 . The Efflux Rate Constant was 0.091 day −1 following dietary uptake of Cu, and the dietary assimilation efficiency (AE) of Cu varied between 1.7% and 10.9% after the fish were fed with three types of prey (oysters, clams and brine shrimp). After the fish were acclimated at a nominal concentration of 50 μg Cu L −1 for 14 days, the Cu uptake Rate and Efflux Rate Constant did not change significantly, but the Cu body concentrations and metallothionein (MT) concentrations in fish tissues increased significantly. Subcellular Cu distributions were also modified. Significant MT induction was observed in response to increased Cu tissue concentrations, indicating that MT rather than the uptake kinetics may play a primary role in Cu regulation during waterborne Cu acclimation in this marine fish. Moreover, the high Cu Efflux may also be important in Cu regulation during long-term exposure. Our modeling calculations indicated that dietary uptake was likely to be the main route for Cu bioaccumulation in the fish, and the relative contribution of waterborne and dietary uptake depended on the bioconcentration factor (BCF) of the prey and ingestion Rate of fish.
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size dependence of the potential for metal biomagnification in early life stages of marine fish
Environmental Toxicology and Chemistry, 2007Co-Authors: Li Zhang, Wen-xiong WangAbstract:We investigated the bioaccumulation of metals (Cd, Se, and Zn) in different juvenile sizes of black sea bream Acanthopagrus schlegeli by applying a biokinetic model. A series of experiments were conducted to determine the physiological kinetic parameters, including uptake Rate Constant of waterborne metals, ingestion Rate, assimilation efficiency of dietary metals, Efflux Rate Constant, and specific growth Rate as a function of fish size. Body concentration of metals as a function of body size was then simulated by the kinetic model and compared with the actual measurements. The uptake Rate Constants decreased with increasing fish size, with an allometric exponent (b) of 0.615 to 0.662. Ingestion Rate was also negatively correlated with the fish size (b = −0.604). Assimilation efficiencies of Cd were independent of body size, whereas those of Se and Zn increased with fish size. In contrast, Efflux Rate Constants and growth Rate Constants for metals were comparable in different sizes of fish. Predicted concentrations of Cd and Zn were comparable to actual measurements and were negatively correlated with fish size. Ingestion Rate was the most important parameter accounting for the size-dependent bioaccumulation of metals, followed by dietary assimilation. We further showed that the trophic transfer potentials of Se and Zn were >1 in smaller fish but then reduced to <1 in larger ones, suggesting that trophic transfer potentials are highly size dependent in marine fish.
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Size-dependence of the potential for metal biomagnification in early life stages of marine fish.
Environmental toxicology and chemistry, 2007Co-Authors: Li Zhang, Wen-xiong WangAbstract:We investigated the bioaccumulation of metals (Cd, Se, and Zn) in different juvenile sizes of black sea bream Acanthopagrus schlegeli by applying a biokinetic model. A series of experiments were conducted to determine the physiological kinetic parameters, including uptake Rate Constant of waterborne metals, ingestion Rate, assimilation efficiency of dietary metals, Efflux Rate Constant, and specific growth Rate as a function of fish size. Body concentration of metals as a function of body size was then simulated by the kinetic model and compared with the actual measurements. The uptake Rate Constants decreased with increasing fish size, with an allometric exponent (b) of 0.615 to 0.662. Ingestion Rate was also negatively correlated with the fish size (b = −0.604). Assimilation efficiencies of Cd were independent of body size, whereas those of Se and Zn increased with fish size. In contrast, Efflux Rate Constants and growth Rate Constants for metals were comparable in different sizes of fish. Predicted concentrations of Cd and Zn were comparable to actual measurements and were negatively correlated with fish size. Ingestion Rate was the most important parameter accounting for the size-dependent bioaccumulation of metals, followed by dietary assimilation. We further showed that the trophic transfer potentials of Se and Zn were >1 in smaller fish but then reduced to
Hans Herlitz - One of the best experts on this subject based on the ideXlab platform.
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Effect of recombinant human growth hormone on cellular sodium metabolism
Clinical Science, 1994Co-Authors: Hans Herlitz, Olof Jonsson, Bengt-Åke BengtssonAbstract:1. The effect of treatment with recombinant human growth hormone on urinary sodium excretion, total body water, the renin-angiotensin system and erythrocyte sodium metabolism was investigated in 16 adults with growth hormone deficiency. 2. Total body water was determined by isotopic dilution, and erythrocyte electrolyte contents were analysed using flame photometry. The Rate of sodium influx and the Efflux Rate Constant of sodium were calculated from values of 22 Na in erythrocytes in vitro. 3. One week of treatment with recombinant human growth hormone caused a decrease in urinary sodium excretion in 9/10 patients and an increase in erythrocyte sodium content
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Cellular sodium transport in severe preeclampsia and chronic hypertension during pregnancy
Hypertension in Pregnancy, 1994Co-Authors: Bo Sultan, Olof Jonsson, Margareta Wennergren, Hans HerlitzAbstract:Background: There are contrasting reports on cation transport during hypertensive pregnancies, with either increased or decreased sodium-potassium pump function compared to normotensive pregnancies.Methods: Intraerythrocyte sodium and potassium content as well as transmembrane sodium transport were investigated in the third trimester in normotensive (n = 11), chronic hypertensive (n = 16), and severe preeclamptic (n = 6) pregnancies.Results: There was a significant decrease in intraerythrocyte potassium content and in sodium Efflux Rate Constant in the severe preeclamptic women. There was no difference between the two hypertensive groups in intraerythrocyte sodium content during pregnancy. Ten of the women with chronic hypertension were followed sequentially at gestational week 24, 30, and 36; and 10 hypertensive women were also studied postpartum. There was a significant decrease in intraerythrocyte sodium and an increasing sodium Efflux Rate Constant with increasing gestational age. When studied postpar...
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Relationship between plasma growth hormone concentration and cellular sodium transport in acromegaly.
Acta endocrinologica, 1992Co-Authors: Hans Herlitz, Olof Jonsson, Bengt-Åke BengtssonAbstract:We investigated the relationship between mean plasma growth hormone (GH) concentration and cellular sodium transport in untreated and treated acromegaly. Seventeen patients (age 55 +/- 3 years) with active acromegaly were studied with respect to plasma GH (mean of 24 h GH profile) and erythrocyte electrolyte content as well as transmembrane sodium transport. The patients were reinvestigated two weeks after successful surgery (N = 14) and again after one year (N = 13). Erythrocyte electrolytes were analyzed by flame photometry and sodium influx and Efflux Rate Constant determined by in vitro incubation using a modified Keyne's formula. In patients with active acromegaly there was a significant positive correlation between IGF-1 and cellular sodium transport, while GH tended to show a negative relationship to the same parameter. After successful treatment, both IGF-1 and GH disclosed a positive relationship to cellular sodium transport. After one year, a significant increase in erythrocyte sodium content was seen in the patients compared to the preoperative situation. In conclusion, if this is a generalized phenomenon the results are compatible with a sodium-retaining effect of GH via stimulation of transmembrane sodium transport. In active acromegaly this may be counteracted by a sodium transport inhibitor giving the reverse relationship between GH and cellular sodium transport.
Bengt-Åke Bengtsson - One of the best experts on this subject based on the ideXlab platform.
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Effect of recombinant human growth hormone on cellular sodium metabolism
Clinical Science, 1994Co-Authors: Hans Herlitz, Olof Jonsson, Bengt-Åke BengtssonAbstract:1. The effect of treatment with recombinant human growth hormone on urinary sodium excretion, total body water, the renin-angiotensin system and erythrocyte sodium metabolism was investigated in 16 adults with growth hormone deficiency. 2. Total body water was determined by isotopic dilution, and erythrocyte electrolyte contents were analysed using flame photometry. The Rate of sodium influx and the Efflux Rate Constant of sodium were calculated from values of 22 Na in erythrocytes in vitro. 3. One week of treatment with recombinant human growth hormone caused a decrease in urinary sodium excretion in 9/10 patients and an increase in erythrocyte sodium content
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Relationship between plasma growth hormone concentration and cellular sodium transport in acromegaly.
Acta endocrinologica, 1992Co-Authors: Hans Herlitz, Olof Jonsson, Bengt-Åke BengtssonAbstract:We investigated the relationship between mean plasma growth hormone (GH) concentration and cellular sodium transport in untreated and treated acromegaly. Seventeen patients (age 55 +/- 3 years) with active acromegaly were studied with respect to plasma GH (mean of 24 h GH profile) and erythrocyte electrolyte content as well as transmembrane sodium transport. The patients were reinvestigated two weeks after successful surgery (N = 14) and again after one year (N = 13). Erythrocyte electrolytes were analyzed by flame photometry and sodium influx and Efflux Rate Constant determined by in vitro incubation using a modified Keyne's formula. In patients with active acromegaly there was a significant positive correlation between IGF-1 and cellular sodium transport, while GH tended to show a negative relationship to the same parameter. After successful treatment, both IGF-1 and GH disclosed a positive relationship to cellular sodium transport. After one year, a significant increase in erythrocyte sodium content was seen in the patients compared to the preoperative situation. In conclusion, if this is a generalized phenomenon the results are compatible with a sodium-retaining effect of GH via stimulation of transmembrane sodium transport. In active acromegaly this may be counteracted by a sodium transport inhibitor giving the reverse relationship between GH and cellular sodium transport.
Olof Jonsson - One of the best experts on this subject based on the ideXlab platform.
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Effect of recombinant human growth hormone on cellular sodium metabolism
Clinical Science, 1994Co-Authors: Hans Herlitz, Olof Jonsson, Bengt-Åke BengtssonAbstract:1. The effect of treatment with recombinant human growth hormone on urinary sodium excretion, total body water, the renin-angiotensin system and erythrocyte sodium metabolism was investigated in 16 adults with growth hormone deficiency. 2. Total body water was determined by isotopic dilution, and erythrocyte electrolyte contents were analysed using flame photometry. The Rate of sodium influx and the Efflux Rate Constant of sodium were calculated from values of 22 Na in erythrocytes in vitro. 3. One week of treatment with recombinant human growth hormone caused a decrease in urinary sodium excretion in 9/10 patients and an increase in erythrocyte sodium content
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Cellular sodium transport in severe preeclampsia and chronic hypertension during pregnancy
Hypertension in Pregnancy, 1994Co-Authors: Bo Sultan, Olof Jonsson, Margareta Wennergren, Hans HerlitzAbstract:Background: There are contrasting reports on cation transport during hypertensive pregnancies, with either increased or decreased sodium-potassium pump function compared to normotensive pregnancies.Methods: Intraerythrocyte sodium and potassium content as well as transmembrane sodium transport were investigated in the third trimester in normotensive (n = 11), chronic hypertensive (n = 16), and severe preeclamptic (n = 6) pregnancies.Results: There was a significant decrease in intraerythrocyte potassium content and in sodium Efflux Rate Constant in the severe preeclamptic women. There was no difference between the two hypertensive groups in intraerythrocyte sodium content during pregnancy. Ten of the women with chronic hypertension were followed sequentially at gestational week 24, 30, and 36; and 10 hypertensive women were also studied postpartum. There was a significant decrease in intraerythrocyte sodium and an increasing sodium Efflux Rate Constant with increasing gestational age. When studied postpar...
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Relationship between plasma growth hormone concentration and cellular sodium transport in acromegaly.
Acta endocrinologica, 1992Co-Authors: Hans Herlitz, Olof Jonsson, Bengt-Åke BengtssonAbstract:We investigated the relationship between mean plasma growth hormone (GH) concentration and cellular sodium transport in untreated and treated acromegaly. Seventeen patients (age 55 +/- 3 years) with active acromegaly were studied with respect to plasma GH (mean of 24 h GH profile) and erythrocyte electrolyte content as well as transmembrane sodium transport. The patients were reinvestigated two weeks after successful surgery (N = 14) and again after one year (N = 13). Erythrocyte electrolytes were analyzed by flame photometry and sodium influx and Efflux Rate Constant determined by in vitro incubation using a modified Keyne's formula. In patients with active acromegaly there was a significant positive correlation between IGF-1 and cellular sodium transport, while GH tended to show a negative relationship to the same parameter. After successful treatment, both IGF-1 and GH disclosed a positive relationship to cellular sodium transport. After one year, a significant increase in erythrocyte sodium content was seen in the patients compared to the preoperative situation. In conclusion, if this is a generalized phenomenon the results are compatible with a sodium-retaining effect of GH via stimulation of transmembrane sodium transport. In active acromegaly this may be counteracted by a sodium transport inhibitor giving the reverse relationship between GH and cellular sodium transport.
Li Zhang - One of the best experts on this subject based on the ideXlab platform.
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effects of acclimation on arsenic bioaccumulation and biotransformation in freshwater medaka oryzias mekongensis after chronic arsenic exposure
Environmental Pollution, 2018Co-Authors: Lizhao Chen, Wei Zhang, Li ZhangAbstract:Fish can acclimate to chronic arsenic (As) exposure, but the mechanisms of acclimation remain unclear to date. Therefore, this study conducted 28-d chronic inorganic As [As(III) and As(V)I exposures in fresh-water medaka (Oryzias mekongensis), examined the As bioaccumulation and biotransformation during exposure, and the As acute toxicity and toxicokinetics after exposure. After chronic As(V) exposure, the 96-h lethal concentration (96-h LC50) of As(V) increased 1.3-fold (from 223 to 286 mu mol/L), indicating that the fish became more tolerant to As(V). The As bioaccumulation in As(V)-exposed fish increased gradually during the initial 21-d exposure period and then decreased at 28 d, indicating that acclimation occurred to regulate the total As levels. Toxicokinetics measurement suggested that As(V) uptake (uptake Rate Constant, k(u)) was significantly decreased and As(III) elimination (Efflux Rate Constant, k(e1)) was significantly increased, both of which could reduce As bioaccumulation. Furthermore, the organic As species became more predominant (50.1-69.3%) in exposed fish, while the inorganic As species were predominant (53.6-56.4%) in the control fish, suggesting that the capability of As biotransformation increased to acclimate inorganic As during chronic exposure. In summary, this study elucidated the acclimation stRategies (reduced bioaccumulation and increased biotransformation) of O. mekongensis to counter the ambient As contamination. (C) 2018 Elsevier Ltd. All rights reserved.
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size dependence of the potential for metal biomagnification in early life stages of marine fish
Environmental Toxicology and Chemistry, 2007Co-Authors: Li Zhang, Wen-xiong WangAbstract:We investigated the bioaccumulation of metals (Cd, Se, and Zn) in different juvenile sizes of black sea bream Acanthopagrus schlegeli by applying a biokinetic model. A series of experiments were conducted to determine the physiological kinetic parameters, including uptake Rate Constant of waterborne metals, ingestion Rate, assimilation efficiency of dietary metals, Efflux Rate Constant, and specific growth Rate as a function of fish size. Body concentration of metals as a function of body size was then simulated by the kinetic model and compared with the actual measurements. The uptake Rate Constants decreased with increasing fish size, with an allometric exponent (b) of 0.615 to 0.662. Ingestion Rate was also negatively correlated with the fish size (b = −0.604). Assimilation efficiencies of Cd were independent of body size, whereas those of Se and Zn increased with fish size. In contrast, Efflux Rate Constants and growth Rate Constants for metals were comparable in different sizes of fish. Predicted concentrations of Cd and Zn were comparable to actual measurements and were negatively correlated with fish size. Ingestion Rate was the most important parameter accounting for the size-dependent bioaccumulation of metals, followed by dietary assimilation. We further showed that the trophic transfer potentials of Se and Zn were >1 in smaller fish but then reduced to <1 in larger ones, suggesting that trophic transfer potentials are highly size dependent in marine fish.
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Size-dependence of the potential for metal biomagnification in early life stages of marine fish.
Environmental toxicology and chemistry, 2007Co-Authors: Li Zhang, Wen-xiong WangAbstract:We investigated the bioaccumulation of metals (Cd, Se, and Zn) in different juvenile sizes of black sea bream Acanthopagrus schlegeli by applying a biokinetic model. A series of experiments were conducted to determine the physiological kinetic parameters, including uptake Rate Constant of waterborne metals, ingestion Rate, assimilation efficiency of dietary metals, Efflux Rate Constant, and specific growth Rate as a function of fish size. Body concentration of metals as a function of body size was then simulated by the kinetic model and compared with the actual measurements. The uptake Rate Constants decreased with increasing fish size, with an allometric exponent (b) of 0.615 to 0.662. Ingestion Rate was also negatively correlated with the fish size (b = −0.604). Assimilation efficiencies of Cd were independent of body size, whereas those of Se and Zn increased with fish size. In contrast, Efflux Rate Constants and growth Rate Constants for metals were comparable in different sizes of fish. Predicted concentrations of Cd and Zn were comparable to actual measurements and were negatively correlated with fish size. Ingestion Rate was the most important parameter accounting for the size-dependent bioaccumulation of metals, followed by dietary assimilation. We further showed that the trophic transfer potentials of Se and Zn were >1 in smaller fish but then reduced to
