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Journal articles on the topic 'Kinetics uptake'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

Manns, P. J., C. R. Tomczak, and R. G. Haennel. "OXYGEN UPTAKE KINETICS." Journal of Cardiopulmonary Rehabilitation and Prevention 29, no. 5 (September 2009): 333. http://dx.doi.org/10.1097/01.hcr.0000361192.80278.bb.

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2

Blakley, Brian W. "Kinetics of Gentamicin Uptake." Otolaryngology–Head and Neck Surgery 121, no. 4 (October 1999): 510. http://dx.doi.org/10.1016/s0194-5998(99)70251-2.

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3

de Jesus, Kelly, Ana Sousa, Karla de Jesus, João Ribeiro, Leandro Machado, Ferran Rodríguez, Kari Keskinen, João Paulo Vilas-Boas, and Ricardo J. Fernandes. "The effects of intensity on V̇O2 kinetics during incremental free swimming." Applied Physiology, Nutrition, and Metabolism 40, no. 9 (September 2015): 918–23. http://dx.doi.org/10.1139/apnm-2015-0029.

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Swimming and training are carried out with wide variability in distances and intensities. However, oxygen uptake kinetics for the intensities seen in swimming has not been reported. The purpose of this study was to assess and compare the oxygen uptake kinetics throughout low-moderate to severe intensities during incremental swimming exercise. We hypothesized that the oxygen uptake kinetic parameters would be affected by swimming intensity. Twenty male trained swimmers completed an incremental protocol of seven 200-m crawl swims to exhaustion (0.05 m·s−1 increments and 30-s intervals). Oxygen uptake was continuously measured by a portable gas analyzer connected to a respiratory snorkel and valve system. Oxygen uptake kinetics was assessed using a double exponential regression model that yielded both fast and slow components of the response of oxygen uptake to exercise. From low-moderate to severe swimming intensities changes occurred for the first and second oxygen uptake amplitudes (P ≤ 0.04), time constants (P = 0.01), and time delays (P ≤ 0.02). At the heavy and severe intensities, a notable oxygen uptake slow component (>255 mL·min−1) occurred in all swimmers. Oxygen uptake kinetics whilst swimming at different intensities offers relevant information regarding cardiorespiratory and metabolic stress that might be useful for appropriate performance diagnosis and training prescription.

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4

Gao, Han, Xiaotian Zhao, Lei Zhou, Fabrizio Sabba, and George F. Wells. "Differential kinetics of nitrogen oxides reduction leads to elevated nitrous oxide production by a nitrite fed granular denitrifying EBPR bioreactor." Environmental Science: Water Research & Technology 6, no. 4 (2020): 1028–43. http://dx.doi.org/10.1039/c9ew00881k.

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5

Balakshin, Mikhail Yu, Chen-Loung Chen, Josef S. Gratzl, Adrianna G. Kirkman, and Harald Jakob. "Kinetic Studies on Oxidation of Veratryl Alcohol by Laccase-Mediator System. Part 2. The Kinetics of Dioxygen Uptake." Holzforschung 54, no. 2 (February 29, 2000): 171–75. http://dx.doi.org/10.1515/hf.2000.029.

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Summary The kinetics of dioxygen uptake in the laccase-catalyzed oxidation of veratryl alcohol with dioxygen in the presence of ABTS, the mediator, was studied. The kinetics of dioxygen uptake consists of two phases: (1) the initial phase up to a reaction time of one hour, and (2) the second phase, after a reaction time of one hour. In the initial phase, ABTS is mainly oxidized to the corresponding cation radical. The kinetics of dioxygen uptake follows a pseudo-zero order rate law. The dioxygen uptake under the reaction condition correlates with the initial ABTS concentration according to the stoichiometric relationship of 0.25 moles dioxygen per mole ABTS. In the second phase, veratryl alcohol is mainly oxidized to veratraldehyde. The kinetics of the dioxygen uptake follows a pseudo-first order rate law. The dioxygen uptake correlates linearly with the yield of veratraldehyde. The stoichiometric ratio between the formation of veratraldehyde and the consumption of dioxygen differs slightly at different M/S ratios. On average, however, it is 0.42 moles of dioxygen per one mole of veratraldehyde formed. The reaction mechanism is discussed on the basis of the kinetic data.

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6

Xu, Fan, and Edward C. Rhodes. "Oxygen Uptake Kinetics During Exercise." Sports Medicine 27, no. 5 (1999): 313–27. http://dx.doi.org/10.2165/00007256-199927050-00003.

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7

Zhou, Jin, Yves Desjardins, and Line Lapointe. "NUTRIENT UPTAKE KINETICS OF CLOUDBERRY." Journal of Plant Nutrition 36, no. 8 (January 2013): 1219–33. http://dx.doi.org/10.1080/01904167.2013.780610.

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8

Pauli, Anneli S. L., and Seppo Kaitala. "Phosphate uptake kinetics byAcinetobacter isolates." Biotechnology and Bioengineering 53, no. 3 (February 5, 1997): 304–9. http://dx.doi.org/10.1002/(sici)1097-0290(19970205)53:3<304::aid-bit9>3.0.co;2-m.

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9

Scheuermann, Barry W., and Thomas J. Barstow. "O2 uptake kinetics during exercise at peak O2 uptake." Journal of Applied Physiology 95, no. 5 (November 2003): 2014–22. http://dx.doi.org/10.1152/japplphysiol.00590.2002.

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Compared with moderate- and heavy-intensity exercise, the adjustment of O2 uptake (V̇o2) to exercise intensities that elicit peak V̇o2 has received relatively little attention. This study examined the V̇o2 response of 21 young, healthy subjects (25 ± 6 yr; mean ± SD) during cycle ergometer exercise to step transitions in work rate (WR) corresponding to 90, 100, and 110% of the peak WR achieved during a preliminary ramp protocol (15-30 W/min). Gas exchange was measured breath by breath and interpolated to 1-s values. V̇o2 kinetics were determined by use of a two- or three-component exponential model to isolate the time constant (τ2) as representative of V̇o2 kinetics and the amplitude (Amp) of the primary fast component independent of the appearance of any V̇o2 slow component. No difference in V̇o2 kinetics was observed between WRs (τ90 = 24.7 ± 9.0; τ100 = 22.8 ± 6.7; τ110 = 21.5 ± 9.2 s, where subscripts denote percent of peak WR; P > 0.05); nor in a subgroup of eight subjects was τ2 different from the value for moderate-intensity (<lactate threshold) exercise (τ2 = 25 ± 12 s, P > 0.05). As expected, the Amp increased with increasing WRs (Amp90 = 2,089 ± 548; Amp100 = 2,165 ± 517; Amp110 = 2,225 ± 559 ml/min; Amp90 vs. Amp110, P < 0.05). However, the gain (G) of the V̇o2 response (ΔV̇o2/ΔWR) decreased with increasing WRs (G90 = 8.5 ± 0.6; G100 = 7.9 ± 0.6; G110 = 7.3 ± 0.6 ml·min-1·W-1; P < 0.05). The Amp of the primary component approximated 85, 88, and 89% of peak V̇o2 during 90, 100, and 110% WR transitions, respectively. The results of the present study demonstrate that, compared with moderate- and heavy-intensity exercise, the gain of the V̇o2 response (as ΔV̇o2/ΔWR) is reduced for exercise transitions in the severe-intensity domain, but the approach to this gain is well described by a common time constant that is invariant across work intensities. The lower ΔV̇o2/ΔWR may be due to an insufficient adjustment of the cardiovascular and/or pulmonary systems that determine O2 delivery to the exercising muscles or due to recruitment of motor units with lower oxidative capacity, after the onset of exercise in the severe-intensity domain.

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10

Postlethwait, E. M., S. D. Langford, and A. Bidani. "Kinetics of NO2 air space absorption in isolated rat lungs." Journal of Applied Physiology 73, no. 5 (November 1, 1992): 1939–45. http://dx.doi.org/10.1152/jappl.1992.73.5.1939.

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We previously showed, during quasi-steady-state exposures, that the rate of inhaled NO2 uptake displays reaction-mediated characteristics (J. Appl. Physiol. 68: 594–603, 1990). In vitro kinetic studies of pulmonary epithelial lining fluid (ELF) demonstrated that NO2 interfacial transfer into ELF exhibits first-order kinetics with respect to NO2, attains [NO2]-dependent rate saturation, and is aqueous substrate dependent (J. Appl. Physiol. 71: 1502–1510, 1991). We have extended these observations by evaluating the kinetics of NO2 gas phase disappearance in isolated ventilating rat lungs. Transient exposures (2–3/lung at 25 degrees C) employed rebreathing (NO2-air) from a non-compliant continuously stirred closed chamber. We observed that 1) NO2 uptake rate is independent of exposure period, 2) NO2 gas phase disappearance exhibited first-order kinetics [initial rate (r*) saturation occurred when [NO2] > 11 ppm], 3) the mean effective rate constant (k*) for NO2 gas phase disappearance ([NO2] < or = 11 ppm, tidal volume = 2.3 ml, functional residual capacity = 4 ml, ventilation frequency = 50/min) was 83 +/- 5 ml/min, 4) with [NO2] < or = 11 ppm, k* and r* were proportional to tidal volume, and 5) NO2 fractional uptakes were constant across [NO2] (< or = 11 ppm) and tidal volumes but exceeded quasi-steady-state observations. Preliminary data indicate that this divergence may be related to the inspired PCO2. These results suggest that NO2 reactive uptake within rebreathing isolated lungs follows first-order kinetics and displays initial rate saturation, similar to isolated ELF.(ABSTRACT TRUNCATED AT 250 WORDS)

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11

Koschate, Jessica, Uwe Drescher, Christian Brinkmann, Klaus Baum, Thorsten Schiffer, Joachim Latsch, Klara Brixius, and Uwe Hoffmann. "Faster heart rate and muscular oxygen uptake kinetics in type 2 diabetes patients following endurance training." Applied Physiology, Nutrition, and Metabolism 41, no. 11 (November 2016): 1146–54. http://dx.doi.org/10.1139/apnm-2016-0001.

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Cardiorespiratory kinetics were analyzed in type 2 diabetes patients before and after a 12-week endurance exercise-training intervention. It was hypothesized that muscular oxygen uptake and heart rate (HR) kinetics would be faster after the training intervention and that this would be detectable using a standardized work rate protocol with pseudo-random binary sequences. The cardiorespiratory kinetics of 13 male sedentary, middle-aged, overweight type 2 diabetes patients (age, 60 ± 8 years; body mass index, 33 ± 4 kg·m−2) were tested before and after the 12-week exercise intervention. Subjects performed endurance training 3 times a week on nonconsecutive days. Pseudo-random binary sequences exercise protocols in combination with time series analysis were used to estimate kinetics. Greater maxima in cross-correlation functions (CCFmax) represent faster kinetics of the respective parameter. CCFmax of muscular oxygen uptake (pre-training: 0.31 ± 0.03; post-training: 0.37 ± 0.1, P = 0.024) and CCFmax of HR (pre-training: 0.25 ± 0.04; post-training: 0.29 ± 0.06, P = 0.007) as well as peak oxygen uptake (pre-training: 24.4 ± 4.7 mL·kg−1·min−1; post-training: 29.3 ± 6.5 mL·kg−1·min−1, P = 0.004) increased significantly over the course of the exercise intervention. In conclusion, kinetic responses to changing work rates in the moderate-intensity range are similar to metabolic demands occurring in everyday habitual activities. Moderate endurance training accelerated the kinetic responses of HR and muscular oxygen uptake. Furthermore, the applicability of the used method to detect these accelerations was demonstrated.

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12

Brandt, Felix, Martina Klinkenberg, Jenna Poonoosamy, Juliane Weber, and Dirk Bosbach. "The Effect of Ionic Strength and Sraq upon the Uptake of Ra during the Recrystallization of Barite." Minerals 8, no. 11 (November 2, 2018): 502. http://dx.doi.org/10.3390/min8110502.

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Recrystallization and solid-solution formation with barite is considered as relevant retention mechanism for 226Ra in long-term scenarios of nuclear waste management. Here, we studied the effect of ionic strength and the presence of Sr in solution upon the Ra-uptake kinetics and final Ra concentrations in solution by recrystallizing barite in solution with varying Sr and NaCl concentration and temperature for up to 1000 days. Final Ra-concentrations were interpreted based on thermodynamic modelling. Our results indicate a slight decrease of the retention potential of barite for Ra but little effect on the uptake kinetics due to the increase of ionic strength from. 0.1 mol/kg to 1.0 mol/kg of NaCl. The final concentrations at solid/liquid ratio of 0.5 g/kg are well described based on available thermodynamic models whereas at 5 g/kg additional Ra uptake probably due to kinetic effects was observed. On the contrary, the presence of Sr in solution can have a significant inhibiting kinetic effect on the uptake kinetics and lower the final Ra-uptake. In some cases, with low solid/liquid ratio or at ambient conditions, Sr completely inhibits barite recrystallization. In all other cases, Ra, Ba and Sr were taken up as thermodynamically predicted at the end of the experiments.

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13

Sands, PJ, and PJ Smethurst. "Modelling Nitrogen Uptake in Ingestad Units Using Michaelis-Menten Kinetics." Functional Plant Biology 22, no. 5 (1995): 823. http://dx.doi.org/10.1071/pp9950823.

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The concept of nutrient flux density was developed to grow plants at a controlled and stable relative growth rate whilst maintaining a constant internal concentration of a limiting nutrient. The method requires frequent and exponentially increasing additions of nutrients to replenish uptake. In developing this approach there has been little reference to Michaelis-Menten-like nutrient uptake kinetics for characterising uptake by roots. This paper applies a simple model of nitrogen-limited plant growth using Michaelis-Menten uptake kinetics to data from previously published experiments based on the nutrient flux density approach. It is shown that the model can indeed reproduce key features of experiments: (1) plant relative growth rate equals nitrogen relative addition rate up to a limit; (2) when nitrogen uptake kinetic parameters are within the range reported in the literature, this limiting growth rate agrees with that observed; and (3) solution nitrogen concentrations are consistent with those published. We suggest that the understanding of nutrient uptake and utilisation by plants could be advanced by jointly considering these two approaches.

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14

Brar, B. S., and A. C. Vig. "Kinetics of phosphate release from soil and its uptake by wheat." Journal of Agricultural Science 110, no. 3 (June 1988): 505–13. http://dx.doi.org/10.1017/s0021859600082071.

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SummaryLaboratory and glasshouse experiments were conducted to study P release kinetics and uptake of P by wheat (Trilicum, aestivum L.) in ten benchmark soils of Punjab (India). Phosphorus desorption, determined by successive extraction with 0·01 m-CaCl2 solution, was lower in calcareous soils (group I) than in non-calcareous soils (group II). Desorption of surface P in soils followed pseudo-first-order kinetics. The values of the kinetic constant of desorption and the radial diffusion coefficient of P increased with the amount of added P in soils.A significant linear relationship between cumulative desorbed P and both dry-matter yield and P uptake indicated that the rate of release of P from the solid matrix is important in determining P uptake by wheat crop. Phosphate uptake was less dependent on the initial solution P concentration than on the rate of phosphate release.

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15

Ruiz-Treviño, F. A., S. González-Martínez, C. Doria-Serrano, and M. Hernández-Esparza. "Phosphorus Release Kinetics in Biofilm Reactors." Water Science and Technology 26, no. 3-4 (August 1, 1992): 567–76. http://dx.doi.org/10.2166/wst.1992.0436.

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This paper presents the kinetic analysis, using Generalized Power-Law equations to describe the results of an experimental investigation conducted on a batch submerged biofilm reactor for phosphorus removal under an anaerobic/aerobic cycle. The observed rates and amounts of phosphorus release and organic substrate uptake in the anaerobic phase leads to a kinetic model in which these two variables are dependent on each other with a non-linear behaviour and reach equilibrium values in both cases, at different times and are function of rate constants ratio. The model has a good fit with experimental data except for C uptake at anaerobic contact times longer than four hours, where other kinetics are implied. Kinetic parameters were obtained with different initial substrate concentrations, anaerobic contact cycles, and type of substrates.

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16

WALSH, L. Michael. "Possible Mechanisms of Oxygen Uptake Kinetics." Annals of physiological anthropology 11, no. 3 (1992): 215–23. http://dx.doi.org/10.2114/ahs1983.11.215.

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17

Robinson, P. K., J. O. Reeve, and K. H. Goulding. "Kinetics of phosphorus uptake by immobilizedChlorella." Biotechnology Letters 10, no. 1 (January 1988): 17–20. http://dx.doi.org/10.1007/bf01030017.

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18

Kim, Suck-Whan, and Ki-Soo Sohn. "Hydrogen uptake kinetics on niobium surfaces." Physical Review B 40, no. 2 (July 15, 1989): 1003–7. http://dx.doi.org/10.1103/physrevb.40.1003.

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19

Menkov, N. D., I. G. Yanchev, and D. I. Zhelyazkov. "Kinetics of wheat flour water uptake." Nahrung/Food 46, no. 2 (March 1, 2002): 76–77. http://dx.doi.org/10.1002/1521-3803(20020301)46:2<76::aid-food76>3.0.co;2-5.

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20

Nguyen, Quan H., and Paul K. Chien. "Cadmium uptake kinetics in human erythrocytes." Biological Trace Element Research 22, no. 2 (November 1989): 119–29. http://dx.doi.org/10.1007/bf02916643.

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21

Koschate, Jessica, Uwe Drescher, Klaus Baum, Christian Brinkmann, Thorsten Schiffer, Joachim Latsch, Klara Brixius, and Uwe Hoffmann. "Heart Rate and Oxygen Uptake Kinetics in Type 2 Diabetes Patients – A Pilot Study on the Influence of Cardiovascular Medication on Regulatory Processes." Experimental and Clinical Endocrinology & Diabetes 125, no. 05 (February 15, 2017): 275–81. http://dx.doi.org/10.1055/s-0042-119526.

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AbstractThe aim of this pilot study was to investigate whether there are differences in heart rate and oxygen uptake kinetics in type 2 diabetes patients, considering their cardiovascular medication. It was hypothesized that cardiovascular medication would affect heart rate and oxygen uptake kinetics and that this could be detected using a standardized exercise test. 18 subjects were tested for maximal oxygen uptake. Kinetics were measured in a single test session with standardized, randomized moderate-intensity work rate changes. Time series analysis was used to estimate kinetics. Greater maxima in cross-correlation functions indicate faster kinetics. 6 patients did not take any cardiovascular medication, 6 subjects took peripherally acting medication and 6 patients were treated with centrally acting medication. Maximum oxygen uptake was not significantly different between groups. Significant main effects were identified regarding differences in muscular oxygen uptake kinetics and heart rate kinetics. Muscular oxygen uptake kinetics were significantly faster than heart rate kinetics in the group with no cardiovascular medication (maximum in cross-correlation function of muscular oxygen uptake vs. heart rate; 0.32±0.08 vs. 0.25±0.06; p=0.001) and in the group taking peripherally acting medication (0.34±0.05 vs. 0.28±0.05; p=0.009) but not in the patients taking centrally acting medication (0.28±0.05 vs. 0.30±0.07; n.s.). It can be concluded that regulatory processes for the achievement of a similar maximal oxygen uptake are different between the groups. The used standardized test provided plausible results for heart rate and oxygen uptake kinetics in a single measurement session in this patient group.

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22

Juliastuti, S. R., J. Baeyens, C. Creemers, and J. Degreve. "Determination of rate parameter for kinetics of nitrification." Jurnal Teknik Kimia Indonesia 4, no. 2 (October 2, 2018): 234. http://dx.doi.org/10.5614/jtki.2005.4.2.7.

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Determination of rate parameter for kinetics of nitrification The nitrification process is the bottleneck step in the total nitrogen removal. The formation of nitrate is considered as the rate limiting step in the whole process and its kinetics determine the design of the nitrification reactor. Heavy metals (Zn2+ and Cu2+) and different organic compounds are used as micropollutants. These kinetics were experimentally measured by respirometry. In line with the aim of the paper, the experimental investigation are conducted to develop design equations to describe kinetic rate relationships under optimum conditions, study the parameter influence such as pH and inhibition by reaction intermediates and inhibition by external pollutants. Results demonstrate that the maximum value of the specific growth rate of autotrophic biomass() is 1.02 day at pH=7 and decreases at pH 7.5; inhibition occurs at substrate (NH4) concentrations in excess of 15 mg N/l; inhibition occurs at increasing concentrations of NO –N and Cu2+ has more pronounced inhibitory effect than Zn2+. The inhibitory effect of organic compounds are listed as the Chlorobenzene > Trichloroethylene> Phenol> Ethyl benzene; the experimental oxygen uptake rate (OUR)-test results the autotrophic kinetic parameter values, which can be used in design equations. Keywords: Respirometry, Autotrophic Biomass, Nitrification, Oxygen Uptake Rate Abstrak Proses nitrifikasi merupakan langkah penting pada penurunan kadar total nitrogen. Pembentukan nitrat dianggap sebagai tahap pembatas kecepatan reaksi pada keseluruhan proses dan kinetikanya menentukan perancangan dari bagian proses nitrifikasi. Logam berat (Zn2+ dan Cu2+) dan berbagai jenis komponen organik digunakan sebagai mikropolutan. Kinetika ini secara eksperimental diukur menggunakan respirometer. Tujuan penelitian adalah mengembangkan persamaan perancangan yang menggambarkan hubungan laju kinetika pada kondisi optimum, studi pengaruh parameter seperti pH, inhibisi karena reaksi intermediat, dan inhibisi oleh polutan dari luar. Hasil penelitian ditunjukkan sebagai berikut: harga laju pertumbuhan biomasa autotrof maksimum spesifik adalah 1,02 hari-1 pada pH=7 dan menurun pada pH 7,5; inhibisi terjadi pada konsentrasi substrat (NH4+) lebih besar dari 15 mg N/l; inhibisi terjadi pada peningkatan konsentrasi NO -N ;Cu2+ lebih dikenal sebagai penyebab inhibisi daripada Zn2+. Efek inhibisi dari komponen organik di daftar mulai dari Chlorobenzene sampai Ethylbenzen. Tes OUR menghasilkan harga parameter kinetika yang dapat dipakai pad apersamaan perencanaan lumpur aktif nitrifikasi. Kata Kunci: Respirometer, BiomasaAutotrof, Nitrifikasi, Laju Kenaikan Oksigen

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23

Drescher, Uwe. "Impact of venous return on pulmonary oxygen uptake kinetics during dynamic exercise: in silico time series analyses from muscles to lungs." Journal of Applied Physiology 125, no. 4 (October 1, 2018): 1150–64. http://dx.doi.org/10.1152/japplphysiol.01058.2017.

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The aim of the present study was to investigate whether a single-compartment (SCM) and a multi-compartment (MCM) venous return model will produce significantly different time-delaying and distortive effects on pulmonary oxygen uptake (V̇o2pulm) responses with equal cardiac outputs (Q̇) and muscle oxygen uptake (V̇o2musc) inputs. For each model, 64 data sets were simulated with alternating Q̇ and V̇o2musc kinetics—time constants (τ) ranging from 10 to 80 s—as responses to pseudorandom binary sequence work rate (WR) changes. Kinetic analyses were performed by using cross-correlation functions (CCFs) between WR with V̇o2pulm and V̇o2musc. Higher maxima of the CCF courses indicate faster system responses—equal to smaller τ values of the variables of interest (e.g., τV̇o2musc). The models demonstrated a highly significant relationship for the resulting V̇o2pulm responses ( r = 0.976, P < 0.001, n = 64). Both models showed significant differences between V̇o2pulm and V̇o2musc kinetics for τV̇o2musc ranging from 10 to 30 s ( P < 0.05 each). In addition, a significant difference in V̇o2pulm kinetics ( P < 0.05) between the models was observed for very fast V̇o2musc kinetics (τ = 10 s). The combinations of fast Q̇ dynamics and slow V̇o2musc kinetics yield distinct deviations in the resultant V̇o2pulm responses compared with V̇o2musc kinetics. Therefore, the venous return models should be used with care and caution if the aim is to infer V̇o2musc by means of V̇o2pulm kinetics. Finally, the resultant V̇o2pulm responses seem to be complex and most likely unpredictable if no cardiodynamic measurements are available in vivo. NEW & NOTEWORTHY A single-compartment and a multi-compartment venous return model were tested to see whether they result in different pulmonary oxygen uptake (V̇o2pulm) kinetics from equal cardiac output and muscle oxygen uptake (V̇o2musc) kinetics. To infer V̇o2musc kinetics by means of V̇o2pulm kinetics, both models should only be used for V̇o2musc time constants ranging from 40 to 80 s. The resultant V̇o2pulm responses seem to be complex and most likely unpredictable if no cardiodynamic measurements are available.

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24

Vilstrup, H., and L. T. Skovgaard. "Kinetics of hepatic alanine uptake and urea synthesis in pigs." American Journal of Physiology-Gastrointestinal and Liver Physiology 254, no. 4 (April 1, 1988): G602—G609. http://dx.doi.org/10.1152/ajpgi.1988.254.4.g602.

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The kinetics of hepatic alanine uptake and urea synthesis in relation to sinusoid alanine concentration was investigated in seven anesthetized pigs weighing 63 kg, using liver vein catheterizations. Each experiment consists of four steady-state periods of 40 min with alanine concentrations in the range of 0.4-27 mmol/l. The process rates were measured as the products of transhepatic concentration gradients and hepatic blood flow rate, determined by indocyanine green. The data suggest that both processes follow saturation kinetics, that there exists a sinusoidal concentration of alanine below which net removal is limited, and that urea synthesis consists of two components: one alanine independent and one depending on alanine concentration according to Michaelis-Menten kinetics. The kinetic parameters were estimated iteratively by the maximum likelihood method. The maximum rate of alanine uptake was 1.13 +/- 0.74 mmol.min-1.kg liver wt-1 (mean +/- SD), the alanine concentration resulting in half-maximum alanine uptake rate was 1.69 +/- 0.99 mmol/l, and the removal-limiting alanine concentration was 0.27 +/- 0.09 mmol/l. The maximum rate of urea-N synthesis was 1.49 +/- 0.87 mmol.min-1.kg liver wt-1, the alanine concentration resulting in half-maximum urea-N synthesis rate was 2.32 +/- 1.11 mmol/l, and the alanine concentration-independent urea-N synthesis rate was 0.13 +/- 0.10 mmol.min-1.kg liver wt-1.

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25

Ouyang, Yu, Jeff N. Tinianow, Simon R. Cherry, and Jan Marik. "Evaluation of 2-[18F]fluoroacetate Kinetics in Rodent Models of Cerebral Hypoxia–Ischemia." Journal of Cerebral Blood Flow & Metabolism 34, no. 5 (February 12, 2014): 836–44. http://dx.doi.org/10.1038/jcbfm.2014.22.

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Glia account for 90% of human brain cells and have a significant role in brain homeostasis. Thus, specific in vivo imaging markers of glial metabolism are potentially valuable. In the brain, 2-fluoroacetate is selectively taken up by glial cells and becomes metabolically trapped in the tricarboxylic acid cycle. Recent work in rodent brain injury models demonstrated elevated lesion uptake of 2-[18F]fluoroacetate ([18F]FACE), suggesting possible use for specifically imaging glial metabolism. To assess this hypothesis, we evaluated [18F]FACE kinetics in rodent models of cerebral hypoxia-ischemia at 3 and 24 hours post insult. Lesion uptake was significantly higher at 30 minutes post injection ( P<0.05). An image-based method for input function estimation using cardiac blood was validated. Analysis of whole blood showed no significant metabolites and plasma activity concentrations of ˜50% that of whole blood. Kinetic models describing [18F]FACE uptake were developed and quantitatively compared. Elevated [18F]FACE uptake was found to be driven primarily by K1/k2 rather than k3, but changes in the latter were detectable. The two-tissue irreversible uptake model (2T3k) was found to be necessary and sufficient for modeling [18F]FACE uptake. We conclude that kinetic modeling of [18F]FACE uptake represents a potentially useful tool for interrogation of glial metabolism.

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26

Armstrong, Neil, and Alan R. Barker. "Oxygen Uptake Kinetics in Children and Adolescents: A Review." Pediatric Exercise Science 21, no. 2 (May 2009): 130–47. http://dx.doi.org/10.1123/pes.21.2.130.

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The pulmonary oxygen uptake (pVO2) kinetic response at the onset of exercise provides a noninvasive window into the metabolic activity of the muscle and a valuable means of increasing our understanding of developmental muscle metabolism. However, to date only limited research has been devoted to investigating the pVO2 kinetic response during exercise in children and adolescents. From the rigorous studies that have been conducted, both age- and sex-related differences have been identified. Specifically, children display a faster exponential rise in the phase II pVO2 kinetics, which are purported to reflect the rise in muscle O2 consumption, during moderate, heavy and very heavy intensity exercise compared with adults. Furthermore, for heavy and very heavy exercise, the O2 cost of exercise is higher for the exponential phase and the magnitude of the pVO2 slow component is smaller in young children. Sex-related differences have been identified during heavy, but not moderate exercise, with prepubertal boys displaying a faster exponential phase II pVO2 kinetic response and a smaller pVO2 slow component compared with prepubertal girls. The mechanisms underlying these differences are currently poorly understood, and form the basis for future research in this area. However, it is hypothesized that an age-related modulation of the muscle phosphate feedback controllers to signal an increased rate of oxidative phosphorylation and/or altered muscle fiber type recruitment strategies have the potential to play an important role. Overall, the data support the view that at the onset of exercise children have an enhanced potential for oxidative metabolism in the myocyte compared with adults.

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27

SIMARD, R. R., J. ZIZKA, and C. R. DE KIMPE. "LE PRÉLÈVEMENT DU K PAR LA LUZERNE (Medicago sativa L.) ET SA DYNAMIQUE DANS 30 SOLS DU QUÉBEC." Canadian Journal of Soil Science 70, no. 3 (August 1, 1990): 379–93. http://dx.doi.org/10.4141/cjss90-038.

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The understanding of the kinetics of K uptake by plants is necessary for the development of predictive models aimed at optimum fertilizer use and crop yields. The objective of this work was to study the kinetics of K uptake by alfalfa, in a long-term growth chamber experiment (366 d), on 30 soils from Quebec. The soils varied in mineralogical composition and by the amounts of available K in soluble, rapidly and slowly exchangeable forms. In 28 of the 30 soils, a minimal, steady-state level of NH4OAc-K was reached after 208 d and six cuts of alfalfa. This minimal level and the K uptakes were qualitatively related to soil texture. Only soils with clay content greater than 35% were still able to supply enough K to maintain alfalfa yields. The kinetics of K uptake was described by two parabolic diffusion equations. In the first 208 d, the rate and amounts of K uptake were better predicted by extracting procedures using a monovalent cation for the exchange. The amount of HNO3-K in the soils was very significantly related to the rate (r = 0.90**) and amount of slowly exchangeable K uptake (r = 0.89**) in the last 158 d of growth. The availability of K was greater in soils rich in feldspar and vermiculite than in soils where illite is a major component. The results of this study indicate that the amounts of HNO3-K and/or the clay content should be integrated into alfalfa fertilizer requirement tables along with amounts of K in soluble and rapidly exchangeable forms for maintenance of alfalfa fields. Key words: Slowly exchangeable K, alfalfa, uptake kinetics, HNO3-K, diffusion, K uptake

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28

Thibodeaux, L. J., K. T. Valsaraj, and D. D. Reible. "Associations between Polychlorinated Biphenyls and Suspended Solids in Natural Waters: An Evaluation of the Uptake Rate by Particles." Water Science and Technology 28, no. 8-9 (October 1, 1993): 215–21. http://dx.doi.org/10.2166/wst.1993.0621.

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The study of the partitioning of PCBs and similar hydrophobic organic chemicals between solid and aqueous phases, such as suspended particles and the water column, has normally been approached from an equilibrium thermodynamic point of view. The kinetics of the uptake process have received some study but this has been limited. This paper presents a rationale for the importance of HOC uptake kinetics. A simple kinetic model is developed and applied to PCB in suspended particles and surface waters. It describes, in practical terms, many of the reported behavioral characteristics of Kd, the partition coefficient, observed both in the laboratory and in the field.

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29

BATISTA, RAQUEL OLIVEIRA, ANTONIO EDUARDO FURTINI NETO, SOAMI FERNANDA CAIO DECCETTI, and CASSIANO SILVA VIANA. "ROOT MORPHOLOGY AND NUTRIENT UPTAKE KINETICS BY AUSTRALIAN CEDAR CLONES." Revista Caatinga 29, no. 1 (March 2016): 153–62. http://dx.doi.org/10.1590/1983-21252016v29n118rc.

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ABSTRACT: Evaluation of root morphology and kinetic parameters assist in the characterization of genotypes in nutrient uptake efficiency. This study characterized Australian cedar clones concerning their nutrient uptake capacity at the seedling stage through root morphology and the kinetics of P, K, Ca, and Mg uptake. The experiment was conducted using a nutrient solution in a greenhouse and growth chamber. Four Australian cedar clones (HE, XF, XD, and XE), provided by Bela Forest View (Empresa Florestal Bela Vista), were tested using a completely randomized design with five repetitions, totaling 20 experimental plots. The length, volume, surface area, average diameter, and root length per diameter class, as well as the uptake parameters Vmax, Km, Cmin, and the estimated inflow of P, K, Ca, and Mg, were determined. The root morphological characteristics varied between Australian cedar clones; clone XD exhibited the largest root system development. The uptake efficiency of P, K, Ca, and Mg varied between cedar Australian clones. When availability differed, clones XE and XF exhibited greater plasticity in the uptake of P and K respectively, and similar results were found for clone HE in the uptake of Ca and Mg.

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30

Morton, R. H. "Delayed or accelerated oxygen uptake kinetics in the transition from prior exercise?" Journal of Applied Physiology 62, no. 2 (February 1, 1987): 844–46. http://dx.doi.org/10.1152/jappl.1987.62.2.844.

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Reported experimental findings are at variance with each other on the question as to whether O2 uptake (VO2) kinetics are delayed, advanced, or remain unaltered in the transition from prior exercise. Critical examination of these studies tend to suggest that not a great deal of reliance can be placed on their evidence in attempting to resolve the question. They seem to display a disregard for the theoretical properties of the VO2 kinetic model used; in some cases incorrect statistical inferences appear to have been made; most are mathematically incomplete; and the experimental designs have not been appropriately chosen so as to examine the whole question of altered VO2 kinetics. These points are detailed and discussed so that future designed experiments obtain sufficient reliable evidence with which to resolve the question.

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31

Ugrina, Marin, Nediljka Vukojević Medvidović, Jelena Perić, and Marina Trgo. "A study of kinetics and successive sorption/desorption of Zn and Cd uptake onto iron-modified zeolite." Clay Minerals 50, no. 1 (March 2015): 117–32. http://dx.doi.org/10.1180/claymin.2015.050.1.11.

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AbstractThe sorption properties of iron-modified zeolite (IMZ) and the kinetics of zinc and cadmium uptake by the IMZ were investigated by the batch method. Two kinetic stages were observed, fast uptake up to 240 min, followed by slow uptake up to equilibrium. Kinetic results were fitted to the reaction and diffusion kinetic models, which indicated that intra-particle diffusion was the rate-limiting step. The Vermeulen’s approximation model was used to predict the quantity of Zn and Cd ions removed per gram of IMZ. The results of the successive sorption and desorption of Zn and Cd ions, with different electrolyte solutions, showed the best desorption efficiency with sodium salt solutions. Four successive repetitions of the sorption/desorption cycles showed a small difference between the amount of sorbed and desorbed Zn and Cd ions from the second to the fourth cycle. This indicates excellent sorption/regeneration properties of the IMZ.

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32

Waldenlind, Elisabet, Svante B. Ross, Jan Sääf, Karl Ekbom, and Lennart Wetterberg. "Concentration and Uptake of 5-Hydroxytryptamine in Platelets from Cluster Headache and Migraine Patients." Cephalalgia 5, no. 1 (March 1985): 45–54. http://dx.doi.org/10.1046/j.1468-2982.1985.0501045.x.

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Concentrations of 5-hydroxytryptamine (5-HT) in platelets were determined in 33 cluster headache patients (17 males) and in 34 migraine patients (16 males) outside attacks. The 5-HT uptake into platelets was measured and the kinetic constants Vmax and Km determined in 26 cluster patients (14 males) and in 30 migraine patients (13 males). Significantly lower 5-HT concentrations in whole blood were found in cluster headache and migraine patients than in 50 healthy controls (19 males). The Vmax and Km values of the 5-HT uptake were significantly lower in cluster headache and migraine patients compared with 22 healthy controls (9 males). The 5-HT concentrations and the kinetics of the 5-HT uptake did not differ between cluster headache and migraine. In healthy controls a significant positive correlation was found between the 5-HT uptake rate at 0.25 μM and Km but not in cluster headache and migraine patients. The 5-HT concentrations in whole blood correlated positively with Vmax and Km, respectively, in cluster headache and with Km in healthy controls but not with Vmax nor with Km in migraine. There was no obvious relation between the kinetics of platelet monoamine oxidase (MAO) and the 5-HT uptake except for an increased incidence of low Vmax of MAO and low Km of the 5-HT uptake in cluster headache. The kinetics of the 5-HT uptake was apparently not related to the state of migraine. The results indicate a possible constitutional trait in cluster headache and migraine expressed as low 5-HT concentrations in whole blood and low Vmax and Km of the 5-HT uptake into platelets.

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33

Hattink, Jasper, Jeroen J. M. de Goeij, and Hubert Th Wolterbeek. "Uptake kinetics of 99Tc in common duckweed." Environmental and Experimental Botany 44, no. 1 (August 2000): 9–22. http://dx.doi.org/10.1016/s0098-8472(00)00045-9.

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34

Ghaly, A. E., A. Snow, and M. Kamal. "Kinetics of Iron Uptake by Wetland Plants." American Journal of Biochemistry and Biotechnology 4, no. 3 (March 1, 2008): 279–87. http://dx.doi.org/10.3844/ajbbsp.2008.279.287.

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35

Koga, Shunsaku, Tomoyuki Shiojiri, Yoshiyuki Fukuba, Yoshiyuki Fukuoka, and Narihiko Kondo. "Pulmonary Oxygen Uptake Kinetics in Nonsteady State." APPLIED HUMAN SCIENCE Journal of Physiological Anthropology 15, no. 1 (1996): 1–4. http://dx.doi.org/10.2114/jpa.15.1.

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36

Liu, C. Z., L. Q. Shi, S. L. Xu, Z. Y. Zhou, S. Z. Luo, and X. G. Long. "Kinetics of hydrogen uptake for getter materials." Vacuum 75, no. 1 (June 2004): 71–78. http://dx.doi.org/10.1016/j.vacuum.2003.12.155.

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37

Fenter, Frederick F., Francois Caloz, and Michel J. Rossi. "Kinetics of Nitric Acid Uptake by Salt." Journal of Physical Chemistry 98, no. 39 (September 1994): 9801–10. http://dx.doi.org/10.1021/j100090a014.

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38

Sousa, Ana C., Pedro Figueiredo, Kelly de Jesus, Paulo Colaço, Eduardo Oliveira, João Paulo Vilas-Boas, and Ricardo Fernandes. "Oxygen Uptake Kinetics At 100% Of Vo2max." Medicine & Science in Sports & Exercise 46 (May 2014): 95. http://dx.doi.org/10.1249/01.mss.0000493456.28321.22.

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39

Koschate, J., U. Drescher, K. Baum, S. Eichberg, T. Schiffer, J. Latsch, K. Brixius, and U. Hoffmann. "Muscular Oxygen Uptake Kinetics in Aged Adults." International Journal of Sports Medicine 37, no. 07 (April 26, 2016): 516–24. http://dx.doi.org/10.1055/s-0042-101413.

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40

Quigg, Antonietta, John R. Reinfelder, and Nicholas S. Fisher. "Copper uptake kinetics in diverse marine phytoplankton." Limnology and Oceanography 51, no. 2 (March 2006): 893–99. http://dx.doi.org/10.4319/lo.2006.51.2.0893.

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41

Lan Smith, S., and Yasuhiro Yamanaka. "Optimization-based model of multinutrient uptake kinetics." Limnology and Oceanography 52, no. 4 (July 2007): 1545–58. http://dx.doi.org/10.4319/lo.2007.52.4.1545.

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42

PILOSOF, A. M. R., R. BOQUET, and G. B. BARTHOLOMAI. "Kinetics of Water Uptake by Food Powders." Journal of Food Science 50, no. 1 (August 25, 2006): 278–79. http://dx.doi.org/10.1111/j.1365-2621.1985.tb13334.x.

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43

Kelly, J. M., and S. A. Barber. "Magnesium uptake kinetics in loblolly pine seedlings." Plant and Soil 134, no. 2 (July 1991): 227–32. http://dx.doi.org/10.1007/bf00012040.

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44

Ghaly. "Kinetics of Manganese Uptake by Wetland Plants." American Journal of Applied Sciences 5, no. 10 (May 1, 2008): 1415–23. http://dx.doi.org/10.3844/ajassp.2008.1415.1423.

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45

SEKI, Humitake. "Eutrophication and microbial uptake kinetics in hydrosphere." Kagaku To Seibutsu 26, no. 6 (1988): 378–85. http://dx.doi.org/10.1271/kagakutoseibutsu1962.26.378.

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46

Coody, Peter N., Lee E. Sommers, and Darrell W. Nelson. "Kinetics of glucose uptake by soil microorganisms." Soil Biology and Biochemistry 18, no. 3 (January 1986): 283–89. http://dx.doi.org/10.1016/0038-0717(86)90062-3.

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47

Drummond, G. B. "Kinetics of sevoflurane uptake by the brain." Anaesthesia 59, no. 2 (February 2004): 188–89. http://dx.doi.org/10.1111/j.1365-2044.2004.03633.x.

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48

Unnithan, Viswanath B., Denise M. Roche, Max Garrard, Kat Holloway, and Simon Marwood. "Oxygen Uptake Kinetics in Trained Female Adolescents." Medicine & Science in Sports & Exercise 42 (May 2010): 545. http://dx.doi.org/10.1249/01.mss.0000385342.00280.af.

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49

Zhang, Yong Yu, Karlman Wasserman, Kathy E. Sietsema, Issahar Ben-Dov, Thomas J. Barstow, Grace Mizumoto, and Cynthia S. Sullivan. "O2 Uptake Kinetics in Response to Exercise." Chest 103, no. 3 (March 1993): 735–41. http://dx.doi.org/10.1378/chest.103.3.735.

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50

Paterson, D. H., D. A. Cunningham, J. G. Pickering, M. A. Babcock, and D. R. Boughner. "Oxygen uptake kinetics in cardiac transplant recipients." Journal of Applied Physiology 77, no. 4 (October 1, 1994): 1935–40. http://dx.doi.org/10.1152/jappl.1994.77.4.1935.

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Our purpose was to examine the gas exchange response to exercise in heart transplant (HT) patients and to characterize the O2 uptake kinetics (tau VO2) during successive square-wave on-transients from loadless cycling to moderate exercise. We hypothesized that with a slow heart rate response (and O2 transport limitation) O2 kinetics would be slowed but that with a repeated exercise initiated while the heart rate remained elevated the tau VO2 would be faster. Six male HT patients performed two ramp-function tests to determine peak O2 uptake (1.32 +/- 0.23 l/min) and ventilation threshold (1.02 +/- 0.16 l/min). Patients subsequently completed two repeats of a square-wave forcing function and repeated this on 2 days. Alveolar gas exchange was measured breath by breath. A monoexponential fit of signal-averaged data of the first exercise on-transient (between days) yielded a significantly slower tau VO2 in HT subjects than in healthy men (mean age 47 yr; n = 8) (77 +/- 26 vs. 45 +/- 4 s). With successive exercise (2nd transition) initiated while HR remained elevated the tau VO2 of HT patients was 46 +/- 17 s. The faster O2 kinetics of the second transition suggests that O2 delivery was enhanced and therefore that the tau VO2 may reflect bioenergetic processes controlling the rate of oxidative metabolism.

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