scholarly journals Gut clearance rate constant, temperature and initial gut contents: a review

1998 ◽  
Vol 20 (5) ◽  
pp. 997-1003 ◽  
Author(s):  
Xabier Irigoien
Keyword(s):  
Constant Temperature ◽  
Rate Constant ◽  
Clearance Rate ◽  
Gut Contents ◽  
Clearance Rate Constant ◽  
Gut Clearance ◽  
Gut Clearance Rate

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

1979 ◽  
Vol 36 (3) ◽  
pp. 247-254 ◽  
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

Validation of the calculation of the clearance rate constant (kmono) of [11C]acetate using parametric kmono image for myocardial oxidative metabolism

2009 ◽  
Vol 36 (8) ◽  
pp. 877-882 ◽  
Author(s):  
Raihan Hussain ◽  
Takashi Kudo ◽  
Testuya Tsujikawa ◽  
Masato Kobayashi ◽  
Yasuhisa Fujibayashi ◽  
...  
Keyword(s):  
Rate Constant ◽  
Oxidative Metabolism ◽  
Clearance Rate ◽  
Clearance Rate Constant ◽  
Myocardial Oxidative Metabolism

scholarly journals Contributions of Degradation and Brain-to-blood Elimination Across the Blood—Brain Barrier to Cerebral Clearance of Human Amyloid-β Peptide(1-40) in Mouse Brain

2013 ◽  
Vol 33 (11) ◽  
pp. 1770-1777 ◽  
Author(s):  
Shingo Ito ◽  
Kohta Matsumiya ◽  
Sumio Ohtsuki ◽  
Junichi Kamiie ◽  
Tetsuya Terasaki
Keyword(s):  
Cerebral Cortex ◽  
Blood Brain Barrier ◽  
Rate Constant ◽  
Clearance Rate ◽  
Amyloid Β ◽  
Brain Barrier ◽  
Amyloid Β Peptide ◽  
Blood Brain ◽  
Mouse Cerebral Cortex ◽  
Clearance Rate Constant

The purpose of the present study was to estimate the relative contributions of degradation and brain-to-blood elimination processes to the clearance of microinjected human amyloid-β peptide(1-40) (hAβ(1-40)) from mouse cerebral cortex, using a solid-phase extraction method together with a newly developed ultraperformance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) quantitation method for intact hAβ(1-40). The clearance rate constant of hAβ(1-40) in mouse cerebral cortex was determined to be 3.21 × 10−2/min under conditions where the saturable brain-to-blood elimination process across the blood–brain barrier (BBB) was expected to be saturated. Thus, this clearance rate constant should mainly reflect degradation. The [125I]hAβ(1-40) elimination rate across the BBB under nonsaturating conditions was determined to be 1.48 × 10−2/min. Inhibition studies suggested that processes sensitive to insulin and phosphoramidon, which inhibit neprilysin, insulin-degrading enzyme, and endothelin-converting enzyme, are involved not only in degradation, but also in elimination of hAβ(1-40). In conclusion, our results suggest a dominant contribution of degradation to cerebral hAβ(1-40) clearance, and also indicate that a sequential process of degradation and elimination of degradation products is involved in cerebral hAβ(1-40) clearance.

scholarly journals Bioaccumulation of Pyraoxystrobin and Its Predictive Evaluation in Zebrafish

Toxics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Wenzhu Wu ◽  
Jing Xu ◽  
Yezhi Dou ◽  
Jia Yu ◽  
Deyang Kong ◽  
...  
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Clearance Rate ◽  
Half Life ◽  
Absorption Rate ◽  
Bioconcentration Factor ◽  
Absorption Rate Constants ◽  
Clearance Rate Constant ◽  
Flow Through

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.

scholarly journals Effect of pretreatments on drying behavior of eggplant

2019 ◽  
Vol 17 (1) ◽  
pp. 105-109
Author(s):  
Md Junaeid Khan ◽  
Farjana Yeasmin ◽  
Md Nazrul Islam ◽  
Raju Ahmmed ◽  
Pabitra Chandra Das ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Rate Constant ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Constant Thickness ◽  
Drying Rate ◽  
Fresh Sample ◽  
Drying Time ◽  
Preservation Method ◽  
Drying Behavior

Eggplant is a familiar and admired vegetable in Bangladesh. It is a highly perishable vegetable and cannot be preserved long. Drying is an ancient preservation method used to extend shelf-life of fruits and vegetables. Different Pretreatments may affect the drying kinetics of foods. A study was conducted to evaluate how pretreatments affect the drying behavior of eggplant. Proximate composition of fresh eggplant was analyzed. The samples of constant thickness (8 mm) were dried at 50°C, 55°C and 60°C to determine the effect of temperature on drying rate constant, while for determining the effect of thickness on rate constant, eggplant slices of 4, 6 and 8 mm thicknesses were dried at a constant temperature of 55°C. It was observed that, drying rate decreased with the increase in thickness and the index ‘n’ was found to be 0.89 at 55°C. Under similar drying condition at constant thickness (8 mm), drying time showed an inverse relationship with temperature. The activation energy (Ea) was calculated as 3.242 Kcal/g-mole. Eggplant slices having the highest thickness (8 mm) were blanched at 70°C, 75°C and 80°C for 1, 2 and 2.5 minutes, respectively using hot water bath to determine the effective blanching time and temperature. It was observed that the samples blanched at 75°C and 80°C for 2 minute were enough to inactivate the enzymes. Pretreated (blanched, sulphited and blanched plus sulphited) eggplant slices having constant thickness (8 mm) were dried at constant temperature of 55°C. The drying time was influenced by pretreatments. The highest drying rate was observed for eggplant slices with blanched plus sulphited (5% KMS solution) samples while eggplant slices with 5%KMS solution dipped for 10 minutes showed the lowest drying rate. In case of fresh slices, drying time was lower than blanched and sulphited samples but higher than blanched plus sulphited samples. Pretreatment was also found effective on the color changes (preservation or degradation). Blanching gave a bright color compared to fresh sample but less bright compared to sulphited samples. In case of SO2 retention, blanched plus sulphited sample showed higher retention than sulphited sample. Sulphited sample retains 44.8 ppm SO2/100g of sulphited sample, while the blanched plus sulphited sample retains 280 ppm SO2/100 g of blanched plus sulphited sample. J. Bangladesh Agril. Univ. 17(1): 105–109, March 2019

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