scholarly journals In vivo analysis of the size- and time-dependent uptake of NaYF4:Yb,Er upconversion nanocrystals by pumpkin seedlings

2015 ◽  
Vol 3 (1) ◽  
pp. 144-150 ◽  
Author(s):  
J. Nordmann ◽  
S. Buczka ◽  
B. Voss ◽  
M. Haase ◽  
K. Mummenhoff
Keyword(s):  
Time Dependent ◽  
Upconversion Nanocrystals ◽  
In Vivo Analysis ◽  
Kinetics Of

We have investigated the kinetics of the uptake and the translocation of nanoparticles of different size in plants.

scholarly journals Evaluation of Cerebral Acetate Transport and Metabolic Rates in the Rat Brain in vivo Using 1H-[13C]-NMR

2010 ◽  
Vol 30 (6) ◽  
pp. 1200-1213 ◽  
Author(s):  
Anant B Patel ◽  
Robin A de Graaf ◽  
Douglas L Rothman ◽  
Kevin L Behar ◽  
Graeme F Mason
Keyword(s):  
Steady State ◽  
Tricarboxylic Acid Cycle ◽  
Exponential Fitting ◽  
Resonance Spectroscopy ◽  
Specific Substrate ◽  
Amino Acid Turnover ◽  
In Vivo Analysis ◽  
Kinetics Of

Acetate is a well-known astrocyte-specific substrate that has been used extensively to probe astrocytic function in vitro and in vivo. Analysis of amino acid turnover curves from 13C-acetate has been limited mainly for estimation of first-order rate constants from exponential fitting or calculation of relative rates from steady-state 13C enrichments. In this study, we used 1H-[13C]-Nuclear Magnetic Resonance spectroscopy with intravenous infusion of [2-13C]acetate-Na+ in vivo to measure the cerebral kinetics of acetate transport and utilization in anesthetized rats. Kinetics were assessed using a two-compartment (neuron/astrocyte) analysis of the 13C turnover curves of glutamate-C4 and glutamine-C4 from [2-13C]acetate-Na+, brain acetate levels, and the dependence of steady-state glutamine-C4 enrichment on blood acetate levels. The steady-state enrichment of glutamine-C4 increased with blood acetate concentration until 90% of plateau for plasma acetate of 4 to 5 mmol/L. Analysis assuming reversible, symmetric Michaelis–Menten kinetics for transport yielded 27±2mmol/L and 1.3±0.3 μmol/g/min for Kt and Tmax, respectively, and for utilization, 0.17±0.24 mmol/L and 0.14±0.02 μmol/g/min for KM_util and Vmax_util, respectively. The distribution space for acetate was only 0.32±0.12 mL/g, indicative of a large excluded volume. The astrocytic and neuronal tricarboxylic acid cycle fluxes were 0.37±0.03 μmol/g/min and 1.41±0.11 μmol/g/min, respectively; astrocytes thus comprised ∼21%±3% of total oxidative metabolism.

scholarly journals Mechanism of bidirectional thermotaxis in Escherichia coli

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Anja Paulick ◽  
Vladimir Jakovljevic ◽  
SiMing Zhang ◽  
Michael Erickstad ◽  
Alex Groisman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Optimal Growth ◽  
Wild Type ◽  
E Coli ◽  
Physiological Relevance ◽  
Cell Accumulation ◽  
Physical Stimuli ◽  
In Vivo Analysis ◽  
Kinetics Of

In bacteria various tactic responses are mediated by the same cellular pathway, but sensing of physical stimuli remains poorly understood. Here, we combine an in-vivo analysis of the pathway activity with a microfluidic taxis assay and mathematical modeling to investigate the thermotactic response of Escherichia coli. We show that in the absence of chemical attractants E. coli exhibits a steady thermophilic response, the magnitude of which decreases at higher temperatures. Adaptation of wild-type cells to high levels of chemoattractants sensed by only one of the major chemoreceptors leads to inversion of the thermotactic response at intermediate temperatures and bidirectional cell accumulation in a thermal gradient. A mathematical model can explain this behavior based on the saturation-dependent kinetics of adaptive receptor methylation. Lastly, we find that the preferred accumulation temperature corresponds to optimal growth in the presence of the chemoattractant serine, pointing to a physiological relevance of the observed thermotactic behavior.

Kinetics of equilibration of radioiodide in individual mouse thyroid follicles in vivo

1991 ◽  
Vol 261 (4) ◽  
pp. E529-E538
Author(s):  
G. Andros ◽  
S. H. Wollman
Keyword(s):  
Relative Concentration ◽  
Time Dependent ◽  
Exit Rate ◽  
Time Intervals ◽  
Individual Mouse ◽  
Follicle Size ◽  
Short Time ◽  
Kinetics Of ◽  
Mouse Thyroid

Microdensitometric measurements were made on autoradiographs of radioiodide localized in mouse thyroids subjected to various degrees of stimulation, in which the formation of organic radioiodide was acutely blocked. Estimates were made of the relative concentrations of radioiodide in lumens and cells of follicles and in the nearby blood vessels. Simple models were introduced to interpret the data. Analysis of the ratio of radioiodide concentrations in the lumen and cells of follicles as a function of follicles size and time after injection indicated that smaller follicles equilibrated faster than larger follicles, that the equilibration was faster the more active the gland was, and that the release of radioiodide from follicles in the less active glands must be characterized by a time-dependent exit rate constant. Analysis of the relative concentration of luminal radioiodide as a function of follicle size at short time intervals and in the steady state indicated that the transport properties of the average epithelial cell were generally independent of follicle size.

scholarly journals Impact of real-time shedding on binding kinetics of membrane-remaining L-selectin to PSGL-1

2019 ◽  
Vol 316 (5) ◽  
pp. C678-C689 ◽  
Author(s):  
Shuang Peng ◽  
Shen-Bao Chen ◽  
Lin-Da Li ◽  
Chun-Fang Tong ◽  
Ning Li ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Real Time ◽  
Jurkat Cells ◽  
Binding Kinetics ◽  
Time Dependent ◽  
Intact Cells ◽  
The Impact ◽  
Kinetics Of

L-selectin shedding induced by various cytokines is crucial in activating neutrophils (PMNs) in inflammatory cascade. While the real-time shedding in vivo lasts ~10 min after PMN activation, the impact of time-dependent shedding on binding kinetics of membrane-remaining L-selectins to its ligands is poorly understood at transient or steady state. Here, we developed an in vitro L-selectin shedding dynamics approach, together with competitive assays of cell adhesion, and proposed a theoretical model for quantifying the impact of real-time shedding on the binding kinetics of membrane-remaining L-selectins to P-selectin glycoprotein ligand-1 (PSGL-1). Our data indicated that the extent of L-selectin shedding on PMA activation is higher, but the terminating time is longer for Jurkat cells than those for human PMNs. Meanwhile, fMLF or IL-8 stimulation yields the longer terminating time than that on PMA stimulation but results in a similar shedding extent for PMNs. L-selectin shedding reduces L-selectin-PSGL-1-mediated cell adhesion in three ways: decreasing membrane-anchored L-selectins, increasing soluble L-selectins competitively binding to ligands, and presenting conformational alteration of membrane-remaining L-selectins themselves. Compared with those on intact cells, the binding affinities of membrane-remaining L-selectin-PSGL-1 pairs were all enhanced at initial and lowered at the late shedding phase for both PMN and Jurkat cells even with varied transition time points. The rolling velocities of both PMNs and Jurkat cells were increased following mechanically or biochemically induced shedding of L-selectin under shear flow. These findings help to further our understanding of the function of time-dependent L-selectin shedding during the inflammation cascade.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim
Keyword(s):  
Chromosome Segregation ◽  
New Technologies ◽  
Early Prophase ◽  
Unique Role ◽  
Kinetochore Assembly ◽  
M Phase ◽  
In Vivo Analysis ◽  
Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

1059: In Vivo Analysis of Chronic Phosphodiesterase-5 Inhibition in Penile Erectile Tissue: No Tachyphylaxis Effect

2005 ◽  
Vol 173 (4S) ◽  
pp. 287-287
Author(s):  
Anhur L. Burnett ◽  
Hunter C. Champion ◽  
Robyn E. Becker ◽  
Melissa F. Kramer ◽  
Tongyun Liu ◽  
...  
Keyword(s):  
Erectile Tissue ◽  
In Vivo Analysis ◽  
Phosphodiesterase 5

In vivo Analysis of Murine Pneumococcal Pneumonia for Mathematical Modelling of Community Aquired Pneumonia

Pneumologie ◽  
2017 ◽  
Vol 71 (S 01) ◽  
pp. S1-S125
Author(s):  
S Berger ◽  
C Gökeri ◽  
U Behrendt ◽  
SM Wienhold ◽  
J Lienau ◽  
...  
Keyword(s):  
Mathematical Modelling ◽  
Pneumococcal Pneumonia ◽  
In Vivo Analysis ◽  
Community Aquired Pneumonia

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

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