Analysis of Hepatocyte Distribution and Survival in Vascular Beds with Cells Marked by 99mTC or Endogenous Dipeptidyl Peptidase IV Activity

1997 ◽  
Vol 6 (4) ◽  
pp. 377-386 ◽  
Author(s):  
Sanjeev Gupta ◽  
Srinivasa Rao G. Vasa ◽  
Pankaj Rajvanshi ◽  
Lionel S. Zuckier ◽  
Christopher J. Palestro ◽  
...  
Keyword(s):  
Rat Hepatocytes ◽  
Liver Parenchyma ◽  
Histochemical Staining ◽  
Time Activity ◽  
Liver Sinusoids ◽  
Pulmonary Capillaries ◽  
Vascular Beds ◽  
Kinetics Of ◽  
Cell Fragments

Knowledge of the kinetics of cell distribution in vascular beds will help optimize engraftment of transplanted hepatocytes. To noninvasively localize transplanted cells in vivo, we developed conditions for labeling rat hepatocytes with 99mTc–pertechnetate. The incorporated 99mTc was bound to intracellular proteins and did not impair cell viability. When 99mTc hepatocytes were intrasplenically injected into normal rats, cells entered liver sinusoids with time–activity curves demonstrating instantaneous cell translocations. 99mTc activity in removed organs was in liver or spleen, and lungs showed little activity. However, when cells were intrasplenically transplanted into rats with portasystemic collaterals, 99mTc appeared in both liver sinusoids and pulmonary alveolar capillaries. To further localize cells, we transplanted DPPIV+ F344 rat hepatocytes into syngeneic DPPIV – recipients. Histochemical staining for DPPIV activity demonstrated engraftment of intrasplenically transplanted cells in liver parenchyma. In contrast, when 99mTc hepatocytes were injected into a peripheral vein, cells were entrapped in pulmonary capillaries but were subsequently broken down with redistribution of 99mTc activity elsewhere. Intact DPPIV+ hepatocytes were identified in lungs, whereas only cell fragments were present in liver, spleen, or kidneys. These findings indicate that although the pulmonary vascular bed offers advantages of easy accessibility and a relatively large capacity, significant early cell destruction is an important limitation.

scholarly journals Intracellular and transcellular transport of secretory component and albumin in rat hepatocytes.

1983 ◽  
Vol 97 (5) ◽  
pp. 1582-1591 ◽  
Author(s):  
E S Sztul ◽  
K E Howell ◽  
G E Palade
Keyword(s):  
Membrane Proteins ◽  
Golgi Complex ◽  
Rat Hepatocytes ◽  
Secretory Component ◽  
Bile Canaliculus ◽  
Sds Page ◽  
Iga Antibody ◽  
Co Precipitation ◽  
Kinetics Of

The intra- and transcellular transports of hepatic secretory and membrane proteins were studied in rats in vivo using [3H]fucose and [35S]cysteine as metabolic precursors. Incorporated radioactivity in plasma, bile, and liver subcellular fractions was measured and the labeled proteins of the Golgi complex, bile, and plasma were separated by SDS PAGE and identified by fluorography. 3H-radioactivity in Golgi fractions peaked at 10 min postinjection (p.i.) and then declined concomitantly with the appearance of labeled glycoproteins in plasma. Maximal secretion of secretory fucoproteins from Golgi occurred between 10 and 20 min p.i. In contrast, the clearance of labeled proteins from Golgi membrane subfractions occurred past 30 min p.i., indicating that membrane proteins leave the Golgi complex at least 30 min later than the bulk of content proteins. A major 80,000-dalton form of secretory component (SC) was identified in the bile by co-precipitation with (IgA)2 by an anti-IgA antibody. An antibody (raised in rabbit) against the biliary 80,000-dalton peptide recognized two larger forms (116,000 and 94,000 dalton), presumably precursors, in Golgi membranes. A comparative study of kinetics of transport of 35S-SC and 35S-albumin showed that albumin peaked in bile at approximately 45 min p.i., whereas the SC peak occurred at 80 min p.i., suggesting that the transit time differs for plasma and membrane proteins that are delivered to the bile canaliculus.

scholarly journals Modeling of the Renal Kinetics of the AT1 Receptor Specific PET Radioligand [11C]KR31173

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Nedim C. M. Gulaldi ◽  
Jinsong Xia ◽  
Tao Feng ◽  
Kelvin Hong ◽  
William B. Mathews ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Compartmental Model ◽  
Radioligand Binding ◽  
Left Kidney ◽  
Binding Parameters ◽  
Retention Parameter ◽  
Time Activity ◽  
Kinetics Of

Purpose. The radioligand [11C]KR31173 has been introduced for PET imaging of the angiotensin II subtype 1 receptor (AT1R). The purpose of the present project was to employ and validate a compartmental model for quantification of the kinetics of this radioligand in a porcine model of renal ischemia followed by reperfusion (IR).Procedures. Ten domestic pigs were included in the study: five controls and five experimental animals with IR of the left kidney. To achieve IR, acute ischemia was created with a balloon inserted into the left renal artery and inflated for 60 minutes. Reperfusion was achieved by deflation and removal of the balloon. Blood chemistries, urine specific gravity and PH values, and circulating hormones of the renin angiotensin system were measured and PET imaging was performed one week after IR. Cortical time-activity curves obtained from a 90 min [11C]KR31173 dynamic PET study were processed with a compartmental model that included two tissue compartments connected in parallel. Radioligand binding quantified by radioligand retention (80 min value to maximum value ratio) was compared to the binding parameters derived from the compartmental model. A binding ratio was calculated asDVR=DVS/DVNS, whereDVSandDVNSrepresented the distribution volumes of specific binding and nonspecific binding. Receptor binding was also determined by autoradiographyin vitro.Results. Correlations between rate constants and binding parameters derived by the convolution and deconvolution curve fittings were significant(r>0.9). Also significant was the correlation between the retention parameter derived from the tissue activity curve (Yret) and the retention parameter derived from the impulse response function (fret). Furthermore, significant correlations were found between these two retention parameters and DVR. Measurements with PET showed no significant changes in the radioligand binding parameters caused by IR, and thesein vivofindings were confirmed by autoradiography performedin vitro.Conclusions. Correlations between various binding parameters support the concept of the parallel connectivity compartmental model. If an arterial input function cannot be obtained, simple radioligand retention may be adequate for estimation ofin vivoradioligand binding.

In vivo measurements of pulmonary angiotensin-converting enzyme kinetics. I. Theory and error analysis

1995 ◽  
Vol 78 (3) ◽  
pp. 1158-1168 ◽  
Author(s):  
J. Markham ◽  
T. J. McCarthy ◽  
M. J. Welch ◽  
D. P. Schuster
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Enzyme Kinetics ◽  
Kinetic Parameters ◽  
Converting Enzyme ◽  
Activity Data ◽  
Time Activity ◽  
Fast Kinetics ◽  
Trans Conformer ◽  
Kinetics Of

We developed a procedure for measuring pulmonary angiotensin-converting enzyme kinetics with fluorine-18 fluorocaptopril and positron emission tomography (PET). The method is based on the application of a compartmental receptor model that represents the kinetics of two species of ligand, presumably the trans and cis conformers of captopril. The input function was characterized and includes corrections for the labeled metabolites of fluorocaptopril. Application of the procedure to lung time-activity data obtained with PET produced estimates of kinetic parameters demonstrating fast kinetics for one conformer and slower kinetics for the other. Simulation studies were performed to evaluate the sensitivity of the estimated parameters to errors in the model assumptions and in measured values for variables required for analysis of the PET data. Estimates for two of the kinetic parameters, the amount of perfused unbound functional enzyme normalized to regional lung volume and the association rate constant for the trans conformer, were relatively stable even with large errors in the input data, varying < 30% from true values for all perturbations. Thus, the procedure produces reliable estimates of the kinetics of the trans conformer of captopril as well as theoretical curves that are close to the observed data.

Kinetics of positron emitters in vivo characterized with a beta probe

1982 ◽  
Vol 242 (1) ◽  
pp. H62-H67 ◽  
Author(s):  
R. A. Lerch ◽  
H. D. Ambos ◽  
S. R. Bergmann ◽  
B. E. Sobel ◽  
M. M. Ter-Pogossian
Keyword(s):  
Gamma Probe ◽  
Region Of Interest ◽  
Time Activity ◽  
Beta Particles ◽  
Positron Emission ◽  
Positron Emitters ◽  
Myocardial Biopsies ◽  
Kinetics Of

To facilitate characterization of regional myocardial kinetics of positron-emitting tracers in vivo without distortion by activity outside the region of interest, a probe was developed and evaluated for monitoring radioactivity by detection of positrons themselves. These particles (beta particles) have a maximal range in tissue of only few millimeters rather than the larger range of gamma photons emitted as a result of positron annihiliation. Regional myocardial time-activity curves were determined in open-chest dogs after intracoronary injection of 0.5-1.5 mCi [15O]H2O, a tracer used for measurement of myocardial blood flow, or 6.0-8.0 mCi [11C]palmitate, a tracer used for noninvasive assessment of myocardial metabolism. Time-activity curves after [11C]palmitate injection clearly delineated specific components of myocardial tracer clearance previously identified in vitro in isolated perfused hearts. Myocardial washout of [15O]H2O was monoexponential for more than 2 min without distortion induced by recirculating tracer in ventricular blood. Reproducibility of measured tracer clearance rates during monoexponential clearance was high based on duplicate determinations for both tracers. The beta-detector probe developed overcomes several intrinsic limitations of gamma-probe systems or well counting of serial myocardial biopsies for studies of positron-emitting tracers in vivo and should facilitate assessment of factors of influencing tracer kinetics in vivo relevant to positron-emission tomography.

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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