scholarly journals Quantifying intracellular single vesicular catecholamine concentration with open carbon nanopipettes to unveil the effect of L‐DOPA on vesicular structure

2021 ◽  
Author(s):  
Andrew G. Ewing ◽  
Keke Hu ◽  
Kim Long Le Vo ◽  
Amir Hatamie
Keyword(s):  
Vesicular Structure ◽  
Catecholamine Concentration

Use of a Catecholamine Sensor in the Control of an Artificial Heart System

1997 ◽  
Vol 20 (1) ◽  
pp. 37-42 ◽  
Author(s):  
K. Mabuchi ◽  
T. Chinzei ◽  
Y. Abe ◽  
K. Imanishi ◽  
T. Isoyama ◽  
...  
Keyword(s):  
Control System ◽  
Plasma Proteins ◽  
Artificial Heart ◽  
Circulatory System ◽  
Reference Electrode ◽  
Mock Circulatory System ◽  
Real Time Measurement ◽  
Artificial Hearts ◽  
Set Up ◽  
Catecholamine Concentration

An electrochemical sensor system to allow real-time measurement and feedback of catecholamine concentrations was developed for use in the control of artificial hearts. Electrochemical analyses were carried out using a carbon fiber working electrode, an Ag-AgCI reference electrode, and a potentiostat. The operating parameters of the pneumatically-driven artificial heart system were altered in accordance with the algorithm for changes in the catecholamine concentration. The minimum detectable concentrations of both adrenaline and noradrenaline in a mock circulatory system using a phosphate-buffered solution were approximately 1-2 ng/ml (10-8 mol/L). An artificial heart control system utilizing this set-up performed satisfactorily without delay, although sensor sensitivity decreased when placed in goat plasma instead of a phosphate-buffered solution, due to the adsorption of various substances such as plasma proteins onto the electrodes. This study demonstrated the future feasibility of a feedback control system for artificial hearts using catecholamine concentrations.

Controllable vesicular structure and reversal of a surfactant-encapsulated polyoxometalate complex

Soft Matter ◽  
2009 ◽  
Vol 5 (20) ◽  
pp. 4047 ◽  
Author(s):  
Yi Yan ◽  
Bao Li ◽  
Wen Li ◽  
Haolong Li ◽  
Lixin Wu
Keyword(s):  
Vesicular Structure

scholarly journals The Endoplasmic Reticulum and the Golgi Structures in Maize Root Cells

1959 ◽  
Vol 5 (3) ◽  
pp. 501-506 ◽  
Author(s):  
W. Gordon Whaley ◽  
Hilton H. Mollenhauer ◽  
Joyce E. Kephart
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Epoxy Resin ◽  
Maize Root ◽  
Root Tips ◽  
Animal Cells ◽  
Root Cells ◽  
Vesicular Structure

Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures. The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system. The Golgi structures appear as stacks of platelet-vesicles which apparently may, under certain conditions, produce small vesicles around their edges. Their form changes markedly with development of the cell.

Relation of thyroid state to myocardial catecholamine concentration

1963 ◽  
Vol 205 (6) ◽  
pp. 1270-1274 ◽  
Author(s):  
George S. Kurland ◽  
Rupert P. Hammond ◽  
A. Stone Freedberg
Keyword(s):  
Body Weight ◽  
Basal Metabolic Rate ◽  
Fluorescence Spectra ◽  
Alumina Column ◽  
Thyroid State ◽  
Norepinephrine Concentration ◽  
Norepinephrine Content ◽  
Alumina Column Chromatography ◽  
Catecholamine Concentration ◽  
Epinephrine Concentration

The myocardial catecholamine content was measured in euthyroid, thyrotoxic, and hypothyroid rabbits. Male rabbits were made thyrotoxic by injection of l-thyroxine, or were rendered hypothyroid by injection of I131. Body weight, basal metabolic rate, serum protein-bound iodine, and appearance were used as criteria of thyroid state. Myocardial norepinephrine and epinephrine concentrations were measured, after alumina column chromatography, by a modification of the trihydroxyindole method. Fluorescence spectra and paper chromatographic analyses confirmed the identity of the trihydroxyindole-fluorescing material, and revealed no extraneous fluorescing substances. In the heart of the euthyroid rabbit, epinephrine concentration averaged 0.3 ± .2 (sd) µg/g in the atrium, and 0.06 ± .03 µg/g in the ventricle. Norepinephrine concentration averaged 2.9 ± .4 µg/g in the atrium, and 2.2 ± .3 µg/g in the ventricle. In thyrotoxicosis, atrial epinephrine and norepinephrine concentrations were decreased, ventricular epinephrine was unchanged, and ventricular norepinephrine was decreased. In hypothyroidism, atrial epinephrine and norepinephrine were decreased and ventricular epinephrine was unchanged, but in the hypothyroid ventricle, norepinephrine content was markedly increased.

Kinetics of enzymatic O-methylation: its value in assays for catecholamines in plasma.

1984 ◽  
Vol 30 (1) ◽  
pp. 24-27 ◽  
Author(s):  
L Mason ◽  
C Weinkove
Keyword(s):  
Mathematical Analysis ◽  
Plasma Catecholamines ◽  
High Concentration ◽  
Internal Standards ◽  
Linear Approximations ◽  
Endogenous Catecholamine ◽  
Radioenzymatic Assay ◽  
Exponential Equations ◽  
Kinetics Of ◽  
Catecholamine Concentration

Abstract The kinetics of enzymatic O-methylation of catecholamines were studied under conditions like those used in the radioenzymatic assay of plasma catecholamines. Inappropriate Michaelis-Menten kinetics and linear approximations of exponential equations were not used. Mathematical analysis indicated the importance of the ratio of methyl donor (S-adenosylmethionine) to substrate (catecholamine) concentration. If the reaction is incomplete, only a large ratio will allow linear approximations between product formed and initial catecholamine concentration. The use of high-concentration internal standards to correct for plasma interference may give erroneous results by reducing this ratio. Accuracy will be improved by ensuring (a) that S-adenosylmethionine is always greatly in excess of catecholamine, (b) that concentrations of added standards are of the same order as for endogenous catecholamine, and (c) that a high activity of enzyme is used, to allow the reaction to reach completion even in the presence of some inhibition.

scholarly journals Self-Assembly of Temperature Sensitive Unilamellar Vesicles by a Blend of Block Copolymers in Aqueous Solution

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 63 ◽  
Author(s):  
Jong Dae Jang ◽  
Changwoo Do ◽  
Joona Bang ◽  
Young Soo Han ◽  
Tae-Hwan Kim
Keyword(s):  
Block Copolymers ◽  
Hydrophobic Interaction ◽  
Self Assembly ◽  
Small Angle Neutron Scattering ◽  
Mass Fraction ◽  
Temperature Sensitive ◽  
Vesicular Structure ◽  
Wide Range ◽  
Scattering Measurements ◽  
Potential Applications

A self-assembled unilamellar vesicle, which can be used as a drug delivery system, was easily and simply fabricated using a blended system of Pluronic block copolymers. Controlling the hydrophilic mass fraction of block copolymers (by blending the block copolymer with a different hydrophilic mass fraction) and temperature (i.e., the hydrophobic interaction is controlled), a vesicular structure was formed. Small angle neutron scattering measurements showed that the vesicular structure had diameters of empty cores from 13.6 nm to 79.6 nm, and thicknesses of the bilayers from 2.2 nm to 8.7 nm when the hydrophobic interaction was changed. Therefore, considering that the temperature of the vesicle formation is controllable by the concentration of the blended block copolymers, it is possible for them to be applied in a wide range of potential applications, for example, as nanoreactors and nanovehicles.

The effect of isolation on catecholamine concentration and turnover in discrete areas of the rat brain

1977 ◽  
Vol 131 (2) ◽  
pp. 259-269 ◽  
Author(s):  
Nguyen B. Thoa ◽  
Yousef Tizabi ◽  
David M. Jacobowitz
Keyword(s):  
Rat Brain ◽  
Catecholamine Concentration
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