Autologous 131I-Antithrombin III Turnover Studies in Man

A simple one-step heparin sepharose preparation of better than 95% pure human antithrombin III (AT3) has been developed along with a modification of the iodine monochloride method that allows consistent iodination of it. Iodination at a ratio of ~0.7 I atom/1.0 AT3 molecule results in loss of ca. 5% total thrombin neutralizing activity but negligible reduction in rate of reaction with thrombin. After iodination with 131I unreached 131I-products are removed by washing the 131I-AT3 on a second heparin sepharose column. Before injection the *I-AT3 is sterilized by millipore filtration. By this method autologous *I-AT3 can be prepared and reinjected into the patient in 36-48 titor less if desired. Serial measurements are made of plasma 131I-AT3, plasma TCA-soluble 131I, and whole body 131I, (using a whole body counter). Since human AT3 is ~ the same molecular weight as albumin if allowance is made for its increased catabolic rate its kinetic behavior should be predictable from results of our earlier studies with human autologous albumin. This is not found to be so and human *I-AT3 shows the same delay in catabolismos dog *I-AT3. Current studies indicate that this anomalous behavior is unlikely to invalidate estimates of AT3 catabolism but may result in considerable errors in estimates of total Interstitial AT3. As with our dog studies these suggest a protective role for AT3 in the interstitial fluids

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Antithrombin III: Biodistribution in Healthy Volunteers

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646045 ◽

1987 ◽

Vol 58 (04) ◽

pp. 1008-1011 ◽

Cited By ~ 8

Author(s):

E A R Knot ◽

E de Jong ◽

J W ten Cate ◽

Liem Kian Gie ◽

E A van Royen

Keyword(s):

Healthy Volunteers ◽

Antithrombin Iii ◽

Compartment Model ◽

Fixed Time ◽

Whole Body ◽

Catabolic Rate ◽

At Iii ◽

Great Vessels ◽

Static Images ◽

Liver Region

SummaryFive healthy volunteers were injected intravenously with 73-90 uCi purified human 131I-Antithrombin III (AT III), specific biological activity 5.6 U/mg. The tracer data were analysed using a three compartment model. The plasma radioactivity half life was 66.2 ± 1.2 (sem) h, the fractional catabolic rate constant of the plasma pool was 0.025 ± 0.002 (sem) h-1. These data were comparable with those described in the literature. Because of the difficulty in translating the mathematical analysis of various compartments into the biological model, biodistribiition was monitored by a gamma camera linked to a DEC PDF 11/34 computer system. Dynamic and static images were obtained at fixed time intervals following the injection of 131I-AT III.Whole body scanning at intervals between the time of injection (t=0)and t=24.5 h showed 131I-AT III distribution over the heart, lungs, liver, spleen and great vessels. Dynamic scanning was performed over the heart, spleen and liver. Overlayed frames in the first ten minutes after the 131I-AT III injection showed the following radioactivity expressed as percentage of the injected dose; 5.9% ± 0.3(sem) over the heart, 10.6% ± 0.9 (sem) over the liver and 1.1% ⊥ 0.1(sem) over the spleen.A slower decline of the radioactivity between t = 0 and t = 24 h; (19%) was measured over the liver compared with the radioactivity disappearance over the heart region. This shows, in combination with the fact that the radioactivity disappearance over the heart was identical with the radioactivity decline measured in the plasma samples that retention of 131I-AT III occurred in the liver. Heparin iv injected 6 h after the 131I-AT III injection in two volunteers induced a sharp increase of radioactivity over the liver region during the scanning demonstrating that heparin enhances the 131I-AT III uptake in the liver.

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Calibration and evaluation of the USAFSAM whole-body counter

PsycEXTRA Dataset ◽

10.1037/e541842008-001 ◽

1969 ◽

Author(s):

John Taboada

Keyword(s):

Whole Body ◽

Body Counter ◽

Whole Body Counter

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Studies of Calcium Absorption in Man Using a CD-2 Whole-Body Counter

Nuklearmedizin ◽

10.1055/s-0037-1620624 ◽

1977 ◽

Vol 16 (04) ◽

pp. 163-167

Author(s):

K. Bakos ◽

Věra Wernischová

Keyword(s):

Calcium Absorption ◽

Whole Body ◽

Control Group ◽

Absorption Process ◽

Whole Body Counter ◽

Absorption Studies ◽

Body Counting ◽

Calcium Load ◽

Calcium Malabsorption ◽

Whole Body Counting

SummaryWhole-body counting makes an important contribution of radioisotope techniques to ȁEin vivo“ absorption studies, in comparison with other methods. In a large number of subjects, the method was tested for its usefulness in the diagnosis of calcium malabsorption. The effects of drugs, of the calcium load in the gut and of the whole-body content of calcium on the absorption process were studied in a control group.

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A Simple and Inexpensive Clinical Whole Body Counter

Nuklearmedizin ◽

10.1055/s-0038-1624972 ◽

1976 ◽

Vol 15 (05) ◽

pp. 248-253

Author(s):

A. K. Basu ◽

S. K. Guha ◽

B. N. Tandon ◽

M. M. Gupta ◽

M. ML. Rehani

Keyword(s):

The Body ◽

Whole Body ◽

Vitro Assay ◽

Body Counter ◽

Optimum Parameters ◽

Whole Body Counter ◽

Single Detector ◽

Background Index ◽

Iodide Crystal

SummaryThe conventional radioisotope scanner has been used as a whole body counter. The background index of the system is 10.9 counts per minute per ml of sodium iodide crystal. The sensitivity and derived sensitivity parameters have been evaluated and found to be suitable for clinical studies. The optimum parameters for a single detector at two positions above the lying subject have been obtained. It has been found that for the case of 131I measurement it is possible to assay a source located at any point in the body with coefficient of variation less than 5%. To add to the versatility, a fixed geometry for in-vitro counting of large samples has been obtained. The retention values obtained by the whole body counter have been found to correlate with those obtained by in-vitro assay of urine and stool after intravenous administration of 51Cr-albumin.

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