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 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 Analysis of Large-Amplitude Pulses in Short Time Intervals: Application to Neuron Interactions

2010 ◽  
Vol 2010 ◽  
pp. 1-15 ◽  
Author(s):  
Gianni Mattioli ◽  
Massimo Scalia ◽  
Carlo Cattani
Keyword(s):  
Dynamical System ◽  
Order Approximation ◽  
Nonlinear Dynamical System ◽  
High Amplitude ◽  
Time Dependent ◽  
Third Order ◽  
Time Intervals ◽  
Nonlinear Dynamical ◽  
Short Time ◽  
Third Order Approximation

This paper deals with the analysis of a nonlinear dynamical system which characterizes the axons interaction and is based on a generalization of FitzHugh-Nagumo system. The parametric domain of stability is investigated for both the linear and third-order approximation. A further generalization is studied in presence of high-amplitude (time-dependent) pulse. The corresponding numerical solution for some given values of parameters are analyzed through the wavelet coefficients, showing both the sensitivity to local jumps and some unexpected inertia of neuron's as response to the high-amplitude spike.

Tissue uptake of insulin and inulin in red and white skeletal muscle in vivo

1992 ◽  
Vol 263 (4) ◽  
pp. H1170-H1176 ◽  
Author(s):  
A. Holmang ◽  
P. Bjorntorp ◽  
B. Rippe
Keyword(s):  
Gastrocnemius Muscle ◽  
Tissue Uptake ◽  
Time Intervals ◽  
Muscle Sample ◽  
Longus Muscle ◽  
Permeability Surface ◽  
High Degree ◽  
Kinetics Of ◽  
Vascular Compartment

By employing a tissue uptake technique, the kinetics of the plasma-interstitial equilibration of radiolabeled insulin, inulin, and albumin were followed in four muscles of differing capillarity in anesthetized rats. The soleus muscle (SOL), and the red portion of the gastrocnemius muscle (RG), as well as the extensor digitorum longus muscle (EDL) and the white portion of the gastrocnemius muscle (WG) were investigated. After constant intravenous tracer infusions and repeated plasma sampling under euglycemic clamp conditions, animals were killed at varying time intervals and the muscles mentioned above were dissected out. The radioactivity of tracer per gram of tissue in each muscle divided by the plasma activity of tracer per milliliter of plasma, i.e., "the plasma equivalent space" of tracer, thus could be followed as a function of time. From this function the permeability-surface area (PS) of inulin as well as the distribution volumes at time 0 (V0) of inulin and insulin and their equilibrium distribution volumes (VE) were assessed. The PS for inulin (in ml.min-1.100 g muscle-1) was 0.52 +/- 0.10 (mean +/- SE) in WG, increasing with more red fibers to 1.37 +/- 0.18 in SOL. Also the inulin interstitial distribution volume (at blood-tissue tracer equilibrium; VE) increased in this order (in ml/100 g) from 7.30 +/- 0.91 in WG to 12.93 +/- 0.89 in SOL. The V0 for insulin was found to be approximately fivefold larger than the plasma volume in each muscle sample, indicating a high degree of binding of insulin to structures within the vascular compartment, conceivably to the vascular endothelium.(ABSTRACT TRUNCATED AT 250 WORDS)

The kinetics of the thermal decomposition and polymerization of ethane and ethylene

1956 ◽  
Vol 233 (1195) ◽  
pp. 465-479 ◽  
Keyword(s):  
Nitric Oxide ◽  
Bimolecular Reaction ◽  
The Other ◽  
Constant Concentration ◽  
Time Intervals ◽  
Bimolecular Reactions ◽  
Higher Hydrocarbons ◽  
Products Of Reaction ◽  
Short Time ◽  
Kinetics Of

The pyrolysis of ethane, ethylene and mixtures of the two gases, has been studied by heating the reactants to 600° C for short time intervals and measuring the products of reaction by chemical analysis. In the case of ethane, the first products are ethylene, hydrogen and a small amount of methane. This reaction is inhibited by nitric oxide. The subsequent reactions, none of which is affected by nitric oxide, involve both ethane and ethylene, and result in the formation of methane (in far greater quantity than that produced from ethane direct), propylene, a compound of the formula C 4 H 8 which may be 1-butene, and higher hydrocarbons. The C 4 H 8 , which attains a constant concentration after a few minutes, is produced by two bimolecular reactions, one involving both ethane and ethylene, and the other ethylene alone. Methane is formed from decomposition of the C 4 H 8 . Propylene and higher hydrocarbons are produced as a result of a bimolecular reaction between C 4 H 8 and ethylene. The kinetics of the proposed mechanism hold good over the widest possible range of ethane + ethylene mixtures. Values for the velocity constants of all these reactions are given, and approximate values of the activation energies have been calculated following a further set of experiments at 450° C.

Frequent Serum Sampling in Healthy Men Discloses Testosterone Peaks Exacerbated by Testosterone Propionate Administration

1997 ◽  
Vol 22 (1) ◽  
pp. 58-65
Author(s):  
Guy R. Brisson ◽  
Ángel Guttiérez Sáinz ◽  
Christiane Ayotte ◽  
Raynald Gareau ◽  
Louis Senécal ◽  
...  
Keyword(s):  
Testosterone Propionate ◽  
Venous Blood ◽  
Serum Testosterone ◽  
Treated Group ◽  
Dissociation Kinetics ◽  
Time Intervals ◽  
Male Athletes ◽  
Cell Release ◽  
Short Time ◽  
Kinetics Of

Interval samplings uncover blood diurnal oscillations for several hormones, highlighting the importance of short time intervals in the disclosure of subtle pulsatile patterns of some peptide hormones, namely LH. In a study designed to develop new probes against steroid misuse, venous blood was sampled at 5-min intervals for 4 hours from 12 eugonadal adult male athletes, 6 receiving transcutaneous administrations of testosterone propionate and 6 placebo subjects. Brief supraphysiologic serum testosterone peaks were disclosed, the amplitude and frequency of these peaks being larger for the treated group. No solid explanation could be given to explain these bursts. Neither the binding/dissociation kinetics of SHBG molecules with and without increased circulating level of dihydrotestosterone, nor brief testosterone-inducing LH bursts, nor increased Leydig cell release could be invoked to explain these peaks. Their occurrence, although relatively rare, could represent a threat and lead to improper treatment. Key words: blood testosterone, transcutaneous administration

A pressure-displacement transducer for measuring brain tissue properties in vivo

1975 ◽  
Vol 38 (1) ◽  
pp. 187-188 ◽  
Author(s):  
Edward K. Walsh ◽  
Alfonso Schettini
Keyword(s):  
Brain Tissue ◽  
Mechanical Response ◽  
Displacement Transducer ◽  
Time Dependent ◽  
Creep Properties ◽  
Tissue Properties ◽  
Short Time ◽  
Made In

A transducer system is described which measures simultaneously the pressure and displacement as the transducer is inserted into the intracranial system. The measurements are made in vivo and with the dura arachnoid membranes intact. The short-time mechanical response of the system as well as the time-dependent relaxation and creep properties can be determined.

scholarly journals Selective inhibition of glucose oxidation by triethyltin in rat brain in vivo

1970 ◽  
Vol 119 (1) ◽  
pp. 95-102 ◽  
Author(s):  
J. E. Cremer
Keyword(s):  
Experimental Data ◽  
Amino Acids ◽  
Glucose Metabolism ◽  
Glucose Oxidation ◽  
Selective Inhibition ◽  
Time Intervals ◽  
Main Action ◽  
Short Time ◽  
The Brain

Results are reported of a comparative study in vivo of the metabolism of [2-14C]-glucose and [1-14C]acetate in brains of rats intoxicated with triethyltin sulphate. The incorporation of 14C from glucose into glutamate, glutamine, γ-aminobutyrate and aspartate was greatly decreased. The incorporation of 14C from acetate into these amino acids was unaffected. The experimental data indicated that the main action of triethyltin was to decrease the rate at which pyruvate formed from glucose is oxidized. Glycolysis was not inhibited. Changes in glucose metabolism in the brain are shown not to be directly due to hypothermia. Some of the advantages of measuring the labelling of intermediates at very short time intervals after the injection of the labelled glucose are demonstrated.

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.

Kinetics of accumulation of radioiodine by thyroid gland: short time intervals

1962 ◽  
Vol 202 (1) ◽  
pp. 182-188 ◽  
Author(s):  
Seymour H. Wollman ◽  
Franklin E. Reed
Keyword(s):  
Experimental Data ◽  
Thyroid Gland ◽  
Blood Serum ◽  
Compartment Model ◽  
Time Intervals ◽  
Binding Process ◽  
Three Compartment Model ◽  
Short Time ◽  
Rats And Mice ◽  
Kinetics Of

The protein-bound radioiodine and radioiodide concentrations in the thyroid gland and serum radioiodide concentrations in rats and mice were measured between 3 and 16 min after injection of radioiodide. The data were compared with predictions of a simple open three-compartment model of the thyroid gland. The model generally fitted the experimental data well. The amount of radioiodine incorporated into organic binding each minute varied from one-third to twice the amount of radioiodide in the thyroid, depending on diet. The data were also compared with previously published results on duplicate sets of animals in which the formation of protein-bound iodine was acutely blocked by a goitrogen. The ability of the thyroid to maintain a concentration of radioiodide elevated above that of blood serum was much less when binding was permitted than when blocked and seems to be due to removal of thyroid radioiodide by the binding process and, in addition in the rat, by increased transport of radioiodide from thyroid to blood.

scholarly journals Circadian variation of the pancreatic islet transcriptome

2016 ◽  
Vol 48 (9) ◽  
pp. 677-687 ◽  
Author(s):  
Kuntol Rakshit ◽  
Jingyi Qian ◽  
Jason Ernst ◽  
Aleksey V. Matveyenko
Keyword(s):  
Pancreatic Islet ◽  
Circadian Variation ◽  
Cell Types ◽  
Biological Pathways ◽  
Time Dependent ◽  
Islet Function ◽  
Stem Analysis ◽  
Data Set ◽  
Short Time

Pancreatic islet failure is a characteristic feature of impaired glucose control in diabetes mellitus. Circadian control of islet function is essential for maintaining proper glucose homeostasis. Circadian variations in transcriptional pathways have been described in diverse cell types and shown to be critical for optimization of cellular function in vivo. In the current study, we utilized Short Time Series Expression Miner (STEM) analysis to identify diurnally expressed transcripts and biological pathways from mouse islets isolated at 4 h intervals throughout the 24 h light-dark cycle. STEM analysis identified 19 distinct chronological model profiles, and genes belonging to each profile were subsequently annotated to significantly enriched Kyoto Encyclopedia of Genes and Genomes biological pathways. Several transcriptional pathways essential for proper islet function (e.g., insulin secretion, oxidative phosphorylation), cell survival (e.g., insulin signaling, apoptosis) and cell proliferation (DNA replication, homologous recombination) demonstrated significant time-dependent variations. Notably, KEGG pathway analysis revealed “protein processing in endoplasmic reticulum - mmu04141” as one of the most enriched time-dependent pathways in islets. This study provides unique data set on time-dependent diurnal profiles of islet gene expression and biological pathways, and suggests that diurnal variation of the islet transcriptome is an important feature of islet homeostasis, which should be taken into consideration for optimal experimental design and interpretation of future islet studies.

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