Polymerization of Enbucrilate/Lipiodol Mixtures In Vivo

2000 ◽  
Author(s):  
Matthew J. Gounis ◽  
Baruch B. Lieber ◽  
L. Nelson Hopkins
Keyword(s):  
High Speed ◽  
Polymerization Kinetics ◽  
Polymerization Process ◽  
Embolic Agent ◽  
Model Parameters ◽  
Normal Brain ◽  
Normal Density ◽  
Precise Knowledge ◽  
Kinetics Of

Abstract Embolization is an endovascular procedure used to treat cerebral arteriovenous malformations (AVMs). AVMs are pathological shunts between arteries and veins, which bypass normal brain structures. An embolic agent commonly used to occlude AVMs is n-butyl 2-cyanoacrylate (NBCA). Although NBCA has shown to be efficacious for this application, precise knowledge of its polymerization process in vivo is needed. Inadvertent occlusion of arterial feeders proximal to the AVM nidus will occur when polymerization of NBCA is too rapid. This may lead to revascularization of the AVM. Conversely, long polymerization times may result in the occlusion of draining veins, with subsequent brain hemorrhage and pulmonary emboli. It is therefore critical to understand the kinetics of the polymerization process to obtain a complete glue cast of the arteriovenous transition (nidus) thus, yielding safe obliteration of the AVM. In order to elucidate the polymerization kinetics of NBCA, we examined the embolization process in the femoral and subclavian arteries of the rabbit. Various embolic agents composed of NBCA/lipiodol mixtures with and without the addition of glacial acetic acid (GAA) were injected. Blood flow through the femoral and subclavian arteries was measured prior to and during embolization. All studies were recorded with high-speed digital subtraction angiography (DSA). Preliminary analysis of the data suggests that flow decay during embolization exhibits a behavior that can be modeled via a lagged-normal density curve. Optimized model parameters vis a vis the experimental data are related to the polymerization kinetics. These parameters can be used to form a quantitative basis of comparison for the various liquid embolic mixtures.

scholarly journals Quantitation of Extrastriatal D2 Receptors Using a Very High-Affinity Ligand (FLB 457) and the Multi-Injection Approach

1999 ◽  
Vol 19 (5) ◽  
pp. 533-546 ◽  
Author(s):  
Jacques Delforge ◽  
Michel Bottlaender ◽  
Christian Loc'h ◽  
Ilonka Guenther ◽  
Chantal Fuseau ◽  
...  
Keyword(s):  
D2 Receptor ◽  
Free Ligand ◽  
Brain Regions ◽  
Model Parameters ◽  
Tracer Injection ◽  
High Affinity ◽  
Precise Knowledge ◽  
Receptor Sites ◽  
Very High

The multi-injection approach has been used to study in baboon the in vivo interactions between the D2 receptor sites and FLB 457, a ligand with a very high affinity for these receptors. The model structure was composed of four compartments (plasma, free ligand, and specifically and unspecifically bound ligands) and seven parameters (including the D2 receptor site density). The arterial plasma concentration, after correction for metabolites, was used as the input function, The experimental protocol, which consisted of three injections of labeled and/or unlabeled ligand, allowed the evaluation of all model parameters from a single positron emission tomography experiment In particular, the concentration of receptor sites available for binding ( B'max) and the apparent in vivo FLB 457 affinity were estimated in seven brain regions, including the cerebellum and several cortex regions, in which these parameters are estimated in vivo for the first time ( B'max is estimated to be 4,0 ± 1.3 pmol/mL in the thalamus and from 0.32 to 1.90 pmol/mL in the cortex), A low receptor density was found in the cerebellum ( B'max = 0.39 ± 0.17 pmol/mL), whereas the cerebellum is usually used as a reference region assumed to be devoid of D2 receptor sites, In spite of this very small concentration (1 % of the striatal concentration), and because of the high affinity of the ligand, we demonstrated that after a tracer injection, most of the PET-measured radioactivity in the cerebellum results from the labeled ligand bound to receptor sites, The estimation of all the model parameters allowed simulations that led to a precise knowledge of the FLB 457 kinetics in all brain regions and gave the possibility of testing the equilibrium hypotheses and estimating the biases introduced by the usual simplified approaches.

Ethanol effects on cardiomyocyte contractility

2000 ◽  
Vol 98 (4) ◽  
pp. 401-407 ◽  
Author(s):  
Leanne M. D. DELBRIDGE ◽  
Pamela J. CONNELL ◽  
Peter J. HARRIS ◽  
Trefor O. MORGAN
Keyword(s):  
High Speed ◽  
Imaging Techniques ◽  
Cardiac Contractility ◽  
Ethanol Exposure ◽  
High Speed Imaging ◽  
Low Concentrations ◽  
Cardiomyocyte Contractility ◽  
Contraction Cycle ◽  
Kinetics Of

Little is known about the direct cardiac effects of socially common sub-intoxication levels of ethanol. Previous studies evaluating the responses of normal cardiomyocytes to short-term ethanol exposure have utilized ethanol concentrations equivalent to extreme intoxication or lethal levels in vivo. The purpose of the present study was to investigate the contractile responses of isolated rat ventricular cardiomyocytes during exposure to relatively low concentrations of ethanol in the range 0.05–0.5% (v/v) (8.6–86 mM) under physiological conditions (3 Hz stimulation; 36 °C; BSA vehicle). High-speed imaging techniques were used to study the kinetics of myocyte contraction, and shortening parameters were calculated for mechanistic evaluation. The concentration–response relationship was not linear and exhibited two plateau phases, suggesting at least two mechanisms of action of ethanol on cardiomyocyte contraction. At 0.05% (8.6 mM), ethanol treatment produced a 14.4% decrease in maximum myocyte shortening. The maximum rates of cell shortening and lengthening were similarly impaired, but there was no effect on contraction cycle timing at this low concentration. At 0.30% (51 mM), ethanol reduced maximum shortening by 40.2%, prolonged excitation–contraction coupling latency and abbreviated the contraction cycle time by 38%. The inotropic modulatory effect of ethanol was exaggerated in the absence of protein in the superfusion buffer. This is the first report which identifies ethanol at 0.05% (v/v) as a modulator of cardiac contractility. Kinetic analyses indicate that the mechanism of action involves disturbance of sarcoplasmic reticulum function, and this may contribute to arrhythmogenic vulnerability – especially in an in vivo context of heightened compensatory sympathetic drive.

scholarly journals Raman Spectroscopic Characterization of Polymerization Kinetics of Cyanoacrylate Embolic Glues for Vascular Embolization

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3362
Author(s):  
Yongjiang Li ◽  
Lei Xiao ◽  
Zian Wang ◽  
Kejie Chen ◽  
Chundong Xue ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Polymerization Kinetics ◽  
Polymerization Rate ◽  
Polymerization Process ◽  
Slow Phase ◽  
Invasive Technique ◽  
Iodized Oil ◽  
Essential Information ◽  
Kinetics Of

Endovascular glue embolization is a minimally invasive technique used to selectively reduce or block the blood supply to specific targeted vessels. Cyanoacrylate glues, mixed with radiopaque iodized oil, have been widely used for vascular embolization owing to their rapid polymerization rate, good penetration ability and low tissue toxicity. Nevertheless, in clinical practice, the selection of the glue–oil proportion and the manual injection process of mixtures are mostly based on empirical knowledge of operators, as the crucial physicochemical effect of polymerization kinetics has rarely been quantitatively investigated. In this study, the Raman spectroscopy is used for studying the polymerization kinetics of n-butyl-cyanoacrylate-based glues mixed with an iodized oil. To simulate the polymerization process during embolization, glue–oil mixtures upon contact with a protein ionic solution mimicking blood plasma are manually constructed and their polymerization kinetics are systematically characterized by Raman spectroscopy. The results demonstrate the feasibility of Raman spectroscopy in the characterization of polymerization kinetics of cyanoacrylate-based embolic glues. The polymerization process of cyanoacrylate-based mixtures consists of a fast polymerization phase followed by a slow phase. The propagation velocity and polymerization time primarily depend on the glue concentrations. The commonly used 50% mixture polymerizes 1 mm over ∼21.8 s, while it takes ∼51 min to extend to 5 mm. The results provide essential information for interventional radiologists to help them understand the polymerization kinetics of embolic glues and thus regulate the polymerization rate for effective embolization.

scholarly journals Model-independent counting of molecules in single-molecule localization microscopy

2016 ◽  
Vol 27 (22) ◽  
pp. 3637-3644 ◽  
Author(s):  
Gerhard Hummer ◽  
Franziska Fricke ◽  
Mike Heilemann
Keyword(s):  
Single Molecule ◽  
Fluorescent Protein ◽  
Model Parameters ◽  
Fluorescent State ◽  
Model Independent ◽  
Counting Statistics ◽  
Kinetics Of ◽  
Single Molecule Localization Microscopy

Most biomolecular processes rely on tightly controlled stoichiometries, from the formation of molecular assemblies to cellular signaling. Single-molecule localization micro­scopy studies of fluorophore blinking offer a promising route to probe oligomeric states. Here we show that the distribution of the number of blinking events assumes a universal functional form, independent of photophysics, under relatively mild assumptions. The number of photophysical states, the kinetics of interconversion, and the fraction of active fluorophores enter as two or three constants. This essentially model-independent formulation allows us to determine molecule counts from fluorophore blinking statistics. The formulas hold even if the fluorophores have many different yet unresolved dark states, as long as there is only a single fluorescent state, or if there are different yet unresolvable fluorescent states, as long as there is only a single dark state. We demonstrate the practical applicability of this approach by quantifying the oligomerization states of membrane proteins tagged with the mEos2 fluorescent protein. We find that the model parameters, obtained by likelihood maximization, are transferable. With the counting statistics being independent of the detailed photophysics and its parameters being transferable, the method should be robust and broadly applicable to counting colocalized molecules in vivo and in vitro.

Polymerization Kinetics of Methacrylic Groups in Organic-Inorganic Hybrid Polymeric Thin Films

2007 ◽  
Vol 1007 ◽  
Author(s):  
Congji Zha ◽  
Xinshi Luo ◽  
Barry Luther-Davies
Keyword(s):  
Thin Films ◽  
Thermal Treatment ◽  
Spectroscopic Technique ◽  
Polymerization Kinetics ◽  
Polymerization Process ◽  
Thermal Curing ◽  
Polymeric Thin Films ◽  
Ft Ir ◽  
Ir Spectroscopic ◽  
Kinetics Of

ABSTRACTIn this paper, the polymerization kinetics of unsaturated double bonds (C=C) in TiO2- and ZrO2-doped hybrid polymeric thin films during UV irradiation and thermal curing is studied by monitoring the variation of C=C absorption band at 1630 cm-1 using FT-IR spectroscopic technique. Experimental results showed that polymerization of the unsaturated C=C groups in the TiO2- and ZrO2-doped hybrid polymers can be realized by either photo-irradiation or thermal treatment. The UV-induced polymerization process is much faster than thermal curing, but a full conversion of C=C groups into polyacrylate chains cannot be achieved without thermal treatment. The catalytic effect of TiO2 and ZrO2 on promoting the polymerization of C=C groups was observed, and the time of UV exposure and thermal curing for cross-linking C=C bonds was found to decrease with the increase of the concentration of TiO2 and ZrO2. The activation energy of the hybrid material containing varied concentration of TiO2 and ZrO2 was calculated, and the results indicated that TiO2 is more active than ZrO2 in promoting the polymerization of the unsaturated C=C bonds. Finally, the mechanisms for TiO2 and ZrO2 enhancing the material's photosensitivity (i.e. promoting polymerization of C=C bonds) have been proposed and discussed.

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.

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.

Hepatobiliary Kinetics of 113mIn-Phenolphthalexon

1981 ◽  
Vol 20 (02) ◽  
pp. 90-93
Author(s):  
P.B. Parab ◽  
U.R. Raikar ◽  
R.D. Ganatra ◽  
M. C. Patel
Keyword(s):  
Biliary Excretion ◽  
Iminodiacetic Acid ◽  
Organ Distribution ◽  
Liver Uptake ◽  
On Line ◽  
Rapid Clearance ◽  
Chemical Purity ◽  
Kinetics Of ◽  
High Liver

Phenolphthalexon, a compound with iminodiacetic acid as a functional group, has been labelled with 113mIn to high chemical purity and its usefulness in studies of biliary excretion patency has been studied. Organ distribution of 113mIn-phenolphthalexon in mice was characterized by high liver uptake (50.8% of the administered dose after 5 min) and rapid clearance through the gall bladder. An animal model for studying obstruction of biliary excretion has been developed. Data on the kinetics of the radiopharmaceutical were obtained by collecting in-vivo data through an on-line computer.

Continuous Quantitative Monitoring of Mural, Platelet-Dependent, Thrombus Kinetics in the Crushed Rat Femoral Vein

1991 ◽  
Vol 65 (04) ◽  
pp. 425-431 ◽  
Author(s):  
F Stockmans ◽  
H Deckmyn ◽  
J Gruwez ◽  
J Vermylen ◽  
R Acland
Keyword(s):  
Thrombus Formation ◽  
Femoral Vein ◽  
Maximum Size ◽  
Digital Analysis ◽  
Video Recordings ◽  
Quantitative Monitoring ◽  
Set Up ◽  
Kinetics Of ◽  
Quantitative Nature

SummaryA new in vivo method to study the size and dynamics of a growing mural thrombus was set up in the rat femoral vein. The method uses a standardized crush injury to induce a thrombus, and a newly developed transilluminator combined with digital analysis of video recordings. Thrombi in this model formed rapidly, reaching a maximum size 391 ± 35 sec following injury, after which they degraded with a half-life of 197 ± 31 sec. Histological examination indicated that the thrombi consisted mainly of platelets. The quantitative nature of the transillumination technique was demonstrated by simultaneous measurement of the incorporation of 111In labeled platelets into the thrombus. Thrombus formation, studied at 30 min interval in both femoral veins, showed satisfactory reproducibility overall and within a given animalWith this method we were able to induce a thrombus using a clinically relevant injury and to monitor continuously and reproducibly the kinetics of thrombus formation in a vessel of clinically and surgically relevant size

Acquired Haemophilia: Functional Study of Antibodies to Factor VIII

1981 ◽  
Vol 45 (03) ◽  
pp. 285-289 ◽  
Author(s):  
J P Allain ◽  
A Gaillandre ◽  
D Frommel
Keyword(s):  
Factor Viii ◽  
Functional Study ◽  
Factor Viii Inhibitor ◽  
Acquired Haemophilia ◽  
Viii Inhibitor ◽  
Kinetics Of ◽  
Antibody Function ◽  
Native Plasma

SummaryFactor VIII complex and its interaction with antibodies to factor VIII have been studied in 17 non-haemophilic patients with factor VIII inhibitor. Low VIII:C and high VIIIR.Ag levels were found in all patients. VIII:WF levels were 50% of those of VTIIRrAg, possibly related to an increase of poorly aggregated and electrophoretically fast moving VIIIR:Ag oligomers.Antibody function has been characterized by kinetics of VIII :C inactivation, saturability by normal plasma and the slope of the affinity curve. Two major patterns were observed:1) Antibodies from 6 patients behaved similarly to those from haemophiliacs by showing second order inhibition kinetics, easy saturability and steep affinity slope (> 1).2) Antibodies from other patients, usually with lower titres, inactivated VIII :C according to complex order kinetics, were not saturable, and had a less steep affinity slope (< 0.7). In native plasma, or after mixing with factor VIII concentrate, antibodies of the second group did not form immune complexes with the whole factor VIII molecular complex. However, dissociation procedures did release some antibodies from apparently low molecular weight complexes formed in vivo or in vitro. For appropriate management of non-haemophilic patients with factor VIII inhibitor, it is important to determine the functional properties of their antibodies to factor VIII.

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