Bioaccumulation of Pyraoxystrobin and Its Predictive Evaluation in Zebrafish

This paper aims to understand the bioaccumulation of pyraoxystrobin in fish. Using a flow-through bioconcentration method, the bioconcentration factor (BCF) and clearance rate of pyraoxystrobin in zebrafish were measured. The measured BCF values were then compared to those estimated from three commonly used predication models. At the exposure concentrations of 0.1 μg/L and 1.0 μg/L, the maximum BCF values for pyraoxystrobin in fish were 820.8 and 265.9, and the absorption rate constants (K1) were 391.0 d−1 and 153.2 d−1, respectively. The maximum enrichment occurred at 12 d of exposure. At the two test concentrations, the clearance rate constant (K2) in zebrafish was 0.5795 and 0.4721, and the half-life (t1/2) was 3.84 d and 3.33 d, respectively. The measured BCF values were close to those estimated from bioconcentration predication models.

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Uptake from Seawater and Clearance of p,p′-DDT by Marine Planktonic Crustacea

Journal of the Fisheries Research Board of Canada ◽

10.1139/f79-040 ◽

1979 ◽

Vol 36 (3) ◽

pp. 247-254 ◽

Cited By ~ 14

Author(s):

Gareth C. H. Harding ◽

W. Peter Vass

Keyword(s):

Surface Area ◽

Rate Constant ◽

Uptake Rate ◽

Rate Constants ◽

Clearance Rate ◽

Dry Weight ◽

Exponential Model ◽

Uptake Rate Constant ◽

Clearance Rate Constant ◽

Planktonic Crustaceans

A simple exponential model is used to interpret the simultaneous uptake and clearance of p,p′-DDT by euphausiids and copepods to and from seawater,[Formula: see text]where [C] and [W] are the concentrations in the organism and seawater, respectively. The clearance rate constant for euphausiids, kj = 0.043/d, is not significantly different from that observed for copepods, 0.048/d. No trend in ki values is detected over the range of p,p′-DDT concentrations in seawater used, 27.8–1388 ng/L. Furthermore, there is a great deal of overlap in the uptake rate constant values between organisms. Uptake rate constants range from 0.76 to 1.21 × 104/d for euphausiids and from 1.04 to 2.51 × 104/d for copepods. There appears to be no need to use a surface-area term if the concentration of p,p′-DDT in the organism is expressed per unit dry weight even though the euphausiids are 2 orders of magnitude larger than copepods. Knowing levels of ΣDDT present in planktonic crustaceans in nature, back calculations suggest that there must be [Formula: see text] ΣDDT/L in seawater. A considerable amount of the ΣDDT reported in seawater must therefore be unavailable to plankters because it is "bound" to particles. Key words: p,p′-DDT, uptake, clearance, surface area, euphausiids, copepods

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Pharmacokinetics of human chorionic gonadotropin after i.m. administration in goats (Capra hircus)

Reproduction ◽

10.1530/rep-12-0093 ◽

2012 ◽

Vol 144 (1) ◽

pp. 77-81 ◽

Cited By ~ 12

Author(s):

M Saleh ◽

M Shahin ◽

W Wuttke ◽

M Gauly ◽

W Holtz

Keyword(s):

Rate Constant ◽

Chorionic Gonadotropin ◽

Human Chorionic Gonadotropin ◽

Half Life ◽

Absorption Rate ◽

Elimination Rate ◽

Elimination Rate Constant ◽

Capra Hircus ◽

Absorption Rate Constant ◽

Biological Half Life

The present investigation addresses the pharmacokinetics of human chorionic gonadotropin (hCG), intramuscularly (i.m.) administered to goats. Nine pluriparous does of the Boer goat breed, 2–6 years of age and weighing 45–60 kg, were administered 500 IU hCG (2 ml Chorulon) deep into the thigh musculature 18 h after superovulatory FSH treatment. Blood samples were drawn from the jugular vein at 2 h intervals for the first 24 h, at 6 h intervals until 42 h, and at 12 h intervals until 114 h after administration. After centrifugation, plasma hCG concentrations were determined by electrochemiluminescence immunoassay. Pharmacokinetical parameters were as follows: lag time, 0.4 (s.e.m. 0.1) h; absorption rate constant, 0.34 (s.e.m. 0.002) h; absorption half-life, 2.7 (s.e.m. 0.5) h; elimination rate constant, 0.02 (s.e.m. 0.002) h; biological half-life, 39.4 (s.e.m. 5.1) h; and apparent volume of distribution, 16.9 (s.e.m. 4.3) l. The plasma hCG profile was characterized by an absorption phase of 11.6 (s.e.m. 1.8) h and an elimination phase of 70.0 (s.e.m. 9.8) h, with considerable individual variation in bioavailability and pharmacokinetical parameters. Biological half-life was negatively correlated (P<0.05) with peak concentration (r=−0.76), absorption rate constant (r=−0.78), and elimination rate constant (r=−0.87). The results indicate that after rapid absorption, hCG remains in the circulation for an extended period. This has to be taken into account when assessing the stimulatory response to hCG treatment on an ovarian level.

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