Bromine-82 contamination in fission product 99mTc-generator eluate

Following receipt of fission product ^99mTc-generators, results of radionuclide purity analysis, performed within 30 min after the first elution, demonstrated detectable levels of a contaminate radionuclide not previously reported. Gamma spectroscopy and half-life determinations confirmed the presence of ⁸²Br. Bromine-82 activity, in eluates from the first elution of 30 generators, received weekly during a 7-month period, ranged from 0.22 Ci (8.235 kBq) to 0.67 Ci (24.68 kBq) per eluate. The ratio of ⁹⁹Mo to ^99mTc ranged from 0.13 nCi to 0.39 nCi per mCi ^99mTc. The presence of ⁸²Br in ^99mTc-generator eluate resulted in falsely elevated ⁹⁹Mo assay determinations using whole vial ⁹⁹Mo assay procedures. For every 0.1 Ci ⁸²Br present in ^99mTc eluate the ⁹⁹Mo assay results were elevated by 1 Ci. Gamma spectroscopy of eluates from additional elutions of these generators failed to detect the presence of ⁸²Br demonstrating the displacement of monovalent bromine anions from the alumina column during the first elution.     

Radiorespirometric study of glucose metabolism in liver-damaged rats

Changes in glucose metabolism in rats during feeding with 3-methyl-4-(dimethylamino)azobenzene(3-Me-DAB) were investigated by radiorespirometry with ¹⁴C-labelled carbohydrates as substrates, in relation to the levels of liver glycolytic enzyme activities.Rats were fed on 0.06% 3-Me-DAB for 7 weeks. Radiorespirometry was carried out by the IP administration of [U-¹⁴C]glucose 2.5 Ci or [1-¹⁴C]acetate 2.0 Ci weekly during the experimental period.In the analysis of the radiorespirometric pattern obtained with [U-¹⁴C]glucose, the peak time (PT) was markedly shortened at week 4. At week 6 of 3-Me-DAB feeding, the peak height (PH) and yield value (YV) both increased significantly with concomitant shortening of PT. The duration of the activation in radiorespirometric parameters was paralleled reasonably well by that of glycolytic enzyme activity; the activation of liver glucose-6-phosphate dehydrogenase (G-6-PDH) shortens PT, while the activation of the tricarboxylic acid (TCA) cycle increases YV.This study showed that the radiorespirometric pattern reflected glucose metabolism in the liver well. In conclusion, radiorespirometric analysis with ¹⁴C-labelled glucose as a substrate may be useful for the clinical diagnosis of liver diseases.     

Evaluation of 111In labelled white blood cells by in vitro functional tests and electron microscopy

We have studied the influence of granulocyte labelling with commercially available ¹¹¹In-oxine, tropolone (trop) or home made ¹¹¹In-Mercapto pyridine (Merc) prepared by the method of Thakur (1985) on the cell structure by electron microscopy and on the cell function by enzymatic tests, random migration, chemotaxis, phagocytosis and bactericidal activity. The granulocytes were labelled with 400 Ci ¹¹¹In-oxine in saline or ¹¹¹In-trop or Merc in plasma. The effect of the chelating agents with and without addition of the tracer was studied (n=4) with varying concentrations: 5–10 g/ml oxine, 10–160 g/ml trop and 1–4 g/ml Merc. Chemotaxis and random migration were not affected by ¹¹¹In-trop and clearly supressed by ¹¹¹In-oxine and Merc; the other tests were normal. The cell structure was disturbed by Merc. The labelling efficiency was excellent with oxine (90%), acceptable with trop (30%–80%) and poor with Merc (10%–25%). Without ¹¹¹In, chemotaxis and random migration were normal up to a concentration of 80 g/ml trop, 8.5 g/ml oxine and 1 g/ml Merc. With addition of ¹¹¹In, chemotaxis and random migration were unaffected up to 80 gmg/ml by trop and markedly supressed by Merc and oxine. It is concluded that labelling with ¹¹¹In-trop assures intact cells.     

In-111 Pseudomonas aeruginosa: A simple method of labeling live bacteria with a gamma-emitting radioisotope

We describe a simple and reliable technique for labeling Pseudomonas aeruginosa with a readily available commercial preparation of indium-111 (¹¹¹In) oxine. Labeling of a heavy bacterial suspension with 500 Ci of commercially prepared ¹¹¹In-oxine resulted in a yield of 0.0004 Ci of cell-associated ¹¹¹In per 10⁶ colony-forming units (CFU). The label was 88% bacterially associated and did not effect viability of the organism. Radiolabeling a gram-negative organism with ¹¹¹In-oxine provides a nontoxic, stable gamma-emitting bacterial tracer.     

Local Administration of NF-κ B Decoy Oligonucleotides to Prevent Restenosis after Balloon Angioplasty: An Experimental Study in New Zealand White Rabbits

Purpose To evaluate the efficacy of NF- B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits.Materials and Methods In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF- B in two different concentrations (1 g: n=14; 10 g: n=8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed.Results NF- B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF- B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm² using 1 g NF- B ODN compared to 0.98 mm² in the control group. The higher dose resulted in a neointimal area of 0.97 mm² compared to 1.07mm² at the control side.Conclusions Local drug delivery of NF- B ODN using the channeled balloon catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.     

125I-β-iodo-D-alanine-synthesis,biodistribution and antimicrobial activity

Methyl N-carbobenzoxy--iodo-D-alaninate (1) served as an intermediate to synthesize methyl -iodo-D-alaninate (2) and -iodo-D-alanine (3). The ¹²⁵I-labeled compound 1 was synthesized by the melt method and used to synthesize ¹²⁵I-labeled compounds 2 and 3. Compound 3 was shown to be substrate for D-amino acid oxidase. It was also shown that compounds 2 and 3 were rapidly eliminated from normal mammalian tissues and that compound 3 inhibited the Escherichia coli growth in a dose-dependent manner at 100–500 g/ml while compound 2 showed no effect at 500 g/ml level. Therefore, it was suggested that compound 3 may serve as an abscess localizing agent.Research carried out at Brookhaven National Laboratory under contract with the U.S. Department of Energy (No. DE-AC-02-76CH00016) and supported by its Office of Health and Environmental Research     

Radiation doses to those accompanying nuclear medicine department patients: a waiting room survey

In a multi-centre European trial we have assessed the radiation dose to those accompanying patients undergoing nuclear medicine investigations. Dosemeters were first calibrated against each other and then used to measure the radiation dose to the nurse or relative while they were in the waiting room. In departments where there was one waiting room the median radiation dose was 13 LSv, and the corresponding figures for where there were two waiting rooms and where the patients were allowed to leave the department with their nurse or relative were 12 and 11 Sv, respectively. These figures are not significantly different. However, we found that the median radiation dose to relatives was 13 Sv while that to nurses was 3 Sv (P<0.01), although the waiting times were not significantly different. The reasons for these differences are discussed. Our data do not support the need for a second waiting room for injected patients in a nuclear medicine department. Correspondence to: L.K. Harding     

Incidence of stunned, hibernating and scarred myocardium in ischaemic cardiomyopathy

Purpose Different criteria to identify residual viability in chronically dysfunctioning myocardium in patients with coronary artery disease (CAD) can be derived by the combined assessment of myocardial blood flow (MBF) and glucose utilisation (MRG) using positron emission tomography (PET). The aim of this study was to evaluate, in a large number of patients, the prevalence of these different patterns by purely quantitative means.Methods One hundred and sixteen consecutive patients with ischaemic cardiomyopathy (LVEF 40%) underwent resting 2D echocardiography to assess regional contractile function (16-segment model). PET with ¹⁵O-labelled water (H₂¹⁵O) and ¹⁸F-fluorodeoxyglucose (FDG) was used to quantify MBF and MRG during hyperinsulinaemic euglycaemic clamp. Dysfunctional segments with normal MBF (0.6 ml min^–1 g^–1) were classified as stunned, and segments with reduced MBF (<0.6 ml min^–1 g^–1) as hibernating if MRG was 0.25 mol min^–1 g^–1. Segments with reduced MBF and MRG <0.20 mol min^–1 g^–1 were classified as transmural scars and segments with reduced MBF and MRG between 0.20 and 0.25 mol min^–1 g^–1 as non-transmural scars.Results Eight hundred and thirty-four (46%) segments were dysfunctional. Of these, 601 (72%) were chronically stunned, with 368 (61%) having normal MRG (0.47±0.20 mol min^–1 g^–1) and 233 (39%) reduced MRG (0.16±0.05 mol min^–1 g^–1). Seventy-four (9%) segments with reduced MBF had preserved MRG (0.40±0.18 mol min^–1 g^–1) and were classified as hibernating myocardium. In addition, 15% of segments were classified as transmural and 4% as non-transmural scar. The mean MBF was highest in stunned myocardium (0.95±0.32 ml min^–1 g^–1), intermediate in hibernating myocardium and non-transmural scars (0.47±0.09 ml min^–1 g^–1 and 0.48±0.08 ml min^–1 g^–1, respectively), and lowest in transmural scars (0.40±0.14 ml min^–1 g^–1, P<0.01). MRG was comparable in hibernating and stunned myocardium with preserved MRG (0.40±0.19 mol min^–1 g^–1 vs 0.46±0.20 mol min^–1 g^–1, NS), and lowest in stunned myocardium with reduced MRG and transmural scars.Conclusion Chronic stunning is more prevalent than expected. The degree of MRG reduction in stunned myocardium may disclose segments at higher risk of permanent damage.     

In vitro and in vivo characterisation of nor-β-CIT: a potential radioligand for visualisation of the serotonin transporter in the brain

Radiolabelled 2-Cabomethoxy-3-(4-iodophenyl)tropane (-CIT) has been used in clinical studies for the imaging of dopamine and serotonin transporters with single-photon emission tomography (SPET). 2-Carbomethoxy-3-(4-iodophenyl)nortropane (nor--CIT) is a des-methyl analogue of -CIT, which in vitro has tenfold higher affinity (IC₅₀=0.36 nM) to the serotonin transporter than -CIT (IC₅₀=4.2 nM). Nor--CIT may thus be a useful radioligand for imaging of the serotonin transporter. In the present study iodine-125 and carbon-11 labelled nor--CIT were prepared for in vitro autoradiographic studies on post-mortem human brain cryosections and for in vivo positron emission tomography (PET) studies in Cynomolgus monkeys. Whole hemisphere autoradiography with [¹²⁵I]nor--CIT demonstrated high binding in the striatum, the thalamus and cortical regions of the human brain. Addition of a high concentration (1 M) of citalopram inhibited binding in the thalamus and the neocortex, but not in the striatum. In PET studies with [¹¹C]nor--CIT there was rapid uptake of radioactivity in the monkey brain (6% of injected dose at 15 min) and high accumulation of radioactivity in the striatum, thalamus and neocortex. Thalamus to cerebellum and cortex to cerebellum ratios were 2.5 and 1.8 at 60 min, respectively. The ratios obtained with [¹¹C]nor--CIT were 20%–40% higher than those previously obtained with [¹¹C]-CIT. Radioactivity in the thalamus and the neocortex but not in the striatum was displaceable with citalopram (5 mg/kg). In conclusion, nor--CIT binds to the serotonin transporter in the primate brain in vitro and in vivo and has potential for PET and SPET imaging of the serotonin transporter in human brain.     

Endobronchial administration of iodine-131 B72.3 monoclonal antibody in patients with lung cancer

We tested the feasibility of endobronchial administration of radiolabelled monoclonal antibodies (MoAbs) and the biodistribution of the radiotracer. Ten patients with histological confirmed adenocarcinoma or squamous cell carcinoma were studied. Nine received 470 Ci (103 g) of Iodine-131-B72.3, a monoclonal antibody reacting against TAG 72 antigen, while one patient received 502 Ci (291 g) of ¹³¹I-4C4, an indifferent antibody used for comparison in a negative control study. The radiolabelled antibody was administered through a flexible fiberoptic bronchoscope and placed on the tumour mass under visual monitoring. Scans with a large field-of-view gamma-camera showed retention of ¹³¹I-B72.3 at the tumour site up to 6–9 days in six of eight patients. No other organs were visualized with the exception of faint activity in the gastrointestinal tract, bladder and thyroid. On the contrary, the indifferent antibody ¹³¹I-4C4 was not retained at the tumour site 6 days after MoAb administration, and more prominent activity was found in the gastrointestinal tract. In one patient the study was not technically adequate because of failure of the delivery system. The vascular compartment contained less than 3% of the administered dose. We conclude that endobronchial administration is a feasible technique and allows stable and specific targetting of bronchial tumours. Furthermore, the low activity found in the plasma and other organs suggests that this approach may be used to deliver therapeutic doses of MoAbs to lung cancers.Preliminary results were presented at the European Nuclear Medicine Congress, August 29-September 2, 1988, Milan, Italy. Offprint request to: S. Del Vecchio     

Polarisationsoptische Untersuchungen der elektrischen Strommarke

Zusammenfassung Verfasser haben die polarisationsoptische Analyse der Strommarke durchgeführt; dazu haben sie die anisotropen Anilin-, Phenol- und Rivanol-Färbeverfahren und die anisotropen Präcipitations-Färbeverfahren mit Methylenblau und Toluidinblau angewendet. Der Widerstand der Fasern wurde mittels Elastase-Verdauung untersucht. Die obigen Reaktionen haben die strukturelle Veränderung der kollagenen Fasern, ihre Lösung in Elastase gezeigt. Die ungewöhnlich große strukturelle Diastase wurde durch die Resultate der Messungsdaten bewiesen; gegenüber der +47m, +51 m Doppelbrechung des unversehrten Kollagens betrug der Wert an der Stelle der Strommarke –106 m., –122 m.Zum Schluß bedanken sich Verfasser bei Professor Dr.Ilona Banga für das ihnen liebenswürdigerweise zur Verfügung gestellte benötigte Elastase crudum.     

ROC analysis in radioimmunoassay: An application to the interpretation of thyroglobulin measurement in the follow-up of thyroid carcinoma

This study is an application of the ROC technique to the determination of threshold values (TV) for the interpretation of serum thyroglobulin (Tg) measurements in the follow-up of differentiated thyroid cancer. Serum Tg was assayed using the Henning kit in 1466 samples from 245 individuals. A local or distant recurrence was assessed by clinical examination, radiological and scintigraphic investigations, and was present in 23 patients. The measurements were divided into four groups: 1) measurements performed less than 6 months after thyroidectomy; 2) measurements performed more than 6 months after thyroidectomy; 3) measurements performed during the suppression of pituitary secretion; 4) measurements performed during withdrawal of the substitutive therapy. An ROC curve was calculated for each group and for each curve three TVs were determined: TV1, TV2, and TV3 corresponding to a high sensitivity, a high specificity and a high sum of sensitivity and specificity respectively. TV1 is 3.12 g/l in the four groups. TV2 is 44 g/l, 19 g/l and 30 g/l, in the first, second, third and fourth groups respectively. TV3 is 35 g/l in the first group, 3.12 g/l in both the second and third groups and 30 g/l in the fourth group. When the classical method allows the determination of only one threshold value, the ROC technique allows us to determine threshold values adapted to both the patient clinical status and the chosen sensitivity or specificity.     

Pretargeting in tumored mice with radiolabeled morpholino oligomer showing low kidney uptake

We have recently shown that accumulation in mouse kidneys of technetium-99m labeled phosphorodiamidate morpholinos (MORFs) increases with the number of cytosines in the base sequence. To improve tumor/kidney ratios in tumored mice, pretargeting studies were performed with a cytosine-free MORF. An 18-mer MORF (5-TCTTCTACTTCACAACTA) was conjugated to the anti-CEA antibody MN14 (Immunomedics) and administered to nude mice bearing LS174T tumors. Thereafter, the ^99mTc-labeled cytosine-free cMORF (5-TAGTTGTGAAGTAGAAGA-amide-MAG₃) was administered. For comparison, the identical study was repeated but with our original pair of 18-mer MORFs (5-GGGTGTACGTCACAACTA-conjugated MN14 and ^99mTc-labeled 5-TAGTTGTGACGTACACCC-amide-MAG₃). Surface plasmon resonance was used to show that the hybridization affinities of the original and the modified pair of MORFs were essentially equal. Hybridization of the cytosine-free cMORF-^99mTc to MN14-MORF was demonstrated in vitro by size-exclusion high-performance liquid chromatography. At 3 h, kidney levels in normal mice were 2.0%ID/organ for the modified cMORF vs. 4.1%ID/organ for the original cMORF sequence, while at 24 h, these values were 0.9% vs 1.8%ID/organ. Pretargeting studies in tumored mice receiving 25 g of conjugated antibody, 0.5 g of labeled cMORF 48 h later, followed by imaging and sacrifice at 3 h showed that kidney levels were reduced using the cytosine-free cMORF. Moreover, tumor accumulation was about 3.6%ID/g and was independent of sequence. The whole-body images clearly reflected the improved tumor to kidney ratios. By choosing a cytosine-free base sequence for pretargeting studies, kidney accumulation of cMORF-^99mTc was reduced without adversely influencing tumor accumulation. The lowering of kidney radioactivity levels in this way may be important to reduce toxicity to this organ in connection with pretargeting radiotherapy studies.     

Usefulness of different myocardial sampling zones for the postmortem diagnosis of myocardial infarction

Summary The diagnosis of myocardial infarction requires the use of a group of tests that are very efficient, quick and inexpensive. Another important consideration is the choice of myocardial sampling zones, especially in cases of differential diagnosis between a cardiac injury secondary to a trauma or violent asphyxia and others, secondary to myocardial infarction. The aim of this work was to choose, through discriminant analysis, the most useful zones of cardiac tissue for the quantification of free fatty acids and free carnitine and for the performance of the K/Na quotient, as biochemical parameters for the postmortem diagnosis of myocardial infarction. According to the discriminant analysis performed, seven zones of cardiac tissue are necessary to achieve a differential diagnosis among myocardial infarction, other natural deaths, and violent deaths with a 71.9% efficacy. Greater diagnostic efficacy was found (78.1%) for differentiating between natural deaths and violent deaths. Offprint requests to: E. Lachica     

Über den natürlichen Thalliumgehalt des menschlichen Körpers

Zusammenfassung Es wird eine neue spektrographische Methode zur Bestimmung von Thallium in biologischem Material beschrieben. Dieses Verfahren besitzt eine große Empfindlichkeit, da durch die Extraktion mit einem Komplexbildner (DADDTC) eine starke Anreicherung erfolgt. Es werden auch physiologische Thalliummengen erfaßt; diese liegen zwischen 0,1–0,6p/kp (Tabelle 1 und 2); es sind auch Werte von 1,0–3,0p/kp gefunden worden.Bei der Untersuchung exhumierter Leichen ist es sehr wichtig, nicht nur das biologische Material, sondern auch die in unmittelbarer Nähe der Leiche befindliche Kleiderreste auf dieses Element zu untersuchen, da Konzentrationsverschiebungen durch die Verwesungsflüssigkeit möglich sind.Bei der Untersuchung einer exhumierten Leiche (eines mit Thallium vergifteten Mannes) konnten in der Kleidung Thalliumkonzentrationen von 16–60 p/kp festgestellt werden, während das biologische Material einen Gehalt von 0,9–4,0 p/kp aufwies (Tabelle 4). Leerproben mit exhumierten Leichen ergaben, beim Vorliegen von nur physiologischen Thalliummengen, keine Anreicherung an der Kleidung.

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Summary A new spectrografical method to determine thallium in biological material is described. This procedure produce great sensivity, as by extraction of the element in complex with DADDTC follows a great enrichment. Physiological amounts of thallium can be registered too; they run up to values between 0.1 and 0.6 p/kp (Table 1 and 2), there are also found values of 1.0–3.0 p/kp.By research of exhumed corpses in order to find this element it is of great importance to investigate not only biological material, but also the rests of clothes direct nearby the corpse, for shifting of concentration by putrefaction-liquid is possible.Investigating a exhumes body (of a man poisoned with thallium) we found in clothes a thallium concentration of 16–60 p/kp, whereas the biological material showed an amount of 0.9–4.0 p/kp (Table 4).Empty-testa with exhumed corpses possessing physiological amounts of thallium yielded no enrichment in clothes.

     

Usefulness of a latex agglutination assay for FDP D-dimer to demonstrate the presence of postmortem blood

D-dimer, a specific fragment resulting from degradation of cross-linked fibrin, is an essential marker for the diagnosis of disseminated intravascular coagulation (DIC). Rapid assay for D-dimer using monoclonal antibody coated-latex particles might be useful for discriminating between postmortem and antemortem blood in bloodstains. We tried to detect D-dimer in nine postmortem blood samples by the rapid latex agglutination assay and to quantify them automatically using the latex photometric immunoassay system. The results showed that all samples were positive and that their amounts of D-dimer were 335–2,800 g/ml (the normal blood level, <1 g/ml; the pathogenic blood level with DIC, 1–100 g/ml). Next, nine stains made of postmortem blood were examined by the rapid latex agglutination assay. The result showed that only one case (D-dimer 335 g/ml blood) showed weak positive while the others (D-dimer 600–2,800 g/ml blood) were positive. The present study indicates that the latex agglutination assay for D-dimer can be useful to demonstrate the presence of postmortem blood.     

The significance of the aminoterminal propeptide of type III procollagen in paroxysmal nocturnal haemoglobinuria and myelofibrosis

The level of the aminoterminal propeptide Col 1–3 of type III procollagen (PC-III) was determined in patients with paroxysmal nocturnal haemoglobinuria (PNH) and primary myelofibrosis (PMF), to study whether PC-III can be used as a parameter for the rate and/or degree of bone marrow replacement with collagen. Normal PC-III levels were found in PNH (6.6±1.1 g/l; N: 8.6±1.8 g/l), while significantly increased levels were found in PMF (24.8±2.2 g/l).During a follow-up of 1 year, a slight increase of 2 g/l occurred in three patients with a stable fibrosis, while one patient with more active disease demonstrated an increase of 25 g/l. Treatment with acetylsalicylic acid led to a decline of PC-III as well as -thromboglobulin level, although normalization did not occur. It was demonstrated by means of gel filtration that the antigens related to the PC-III peptide were heterogenous, and that in PMF at least two main peaks were present, with molecular masses equal to and smaller than PC-III peptide.These data demonstrate that the radioimmunoassay cannot be used for the quantitative determination of PC-III; nevertheless it gives some insight in the process of bone marrow fibrosis.     

Verluste bei der Bestimmung kleinster Arsenmengen und ihre radiochemische Überprüfung

Zusammenfassung Überprüfung der Analysenmethode vonVaák-edivec zur Arsen-bestimmung im biologischen Material mit As⁷⁴. Bei genauer Einhaltung bestimmter Analysenbedingungen, die in zahlreichen Versuchen ermittelt wurden, belaufen sich die Arsen Verluste, auch bei Anwesenheit sehr kleiner As-Mengen (ca. 0,1 g und weniger) auf annähernd 5–6%. Vergleichende Versuche mit anderen entsprechenden Analysenmethoden (Gutzeit, Marsh, Testflecken usw.) führen zu wesentlich schlechteren Ergebnissen.

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Summary The methods ofVaák-edivec for the measurement of As in biological samples is controlled by addition of As⁷⁴. Under meticulous observation of certain analytic conditions, which had been found out in many experiments, the loss of As in this modified analytic method amounts to about 4–6%; even when only 0,1 g As is present. Comparative tests of other corresponding methods (Gutzeit, Marsh, Testspot) lead to less exact results.

     

Radiopharmacokinetics and radiation dose from 99mTc-HM-PAO (Preliminary report)

Whole body retention measurements were performed in volunteers after i.v. injection of ^99mTc-HM-PAO (Ceretec^®). The organ accumulation was measured in mice and data were transferred to standard man according to ICRP. Absorbed dose calculations were made with these data by using the concept of absorbed fractions (MIRD method). In man, the whole body retention and the retention in the brain could be calculated by direct measurement, absorbed doses to the other organs could only be derived from animal data. The absorbed dose to the brain derived from human data (10.3 Gy/MBq) is greater by a factor of 2 than that derived from animal data. The highest absorbed dose was received by the thyroid (24.4 Gy/MBq), the absorbed dose to the ovaries, testes and whole body ranged from 2.8 to 4.2 Gy/MBq.Dedicated to Professor Dr. Guenter Liess on the occasion of his 65th anniversary     

Dosimetry of iodoantipyrine

Dosimetry of iodoantipyrine labeled with radioactive iodine was determined by measuring the biodistribution of ¹³¹I-iodoantipyrine in 41 female rabbits. Following administration of the radiopharmaceutical, subjects were killed at 0.5, 6, 12, 17, 24, 36, and 48 h. Organs and samples of tissues and body fluids were assayed. Results were corrected for physical decay. Exponential functions were employed to describe the time-concentration curves; representative value would be the biological half life of 9.96±0.55 h for blood. Cumulated activity estimates for ¹²³I, ¹²⁵I and ¹³¹I were then computed. Extrapolation to absorbed dose in humans followed the formulation of the Medical International Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine. The whole body absorbed doses are 7 Gray, 5 Gray and 29 Gray per MBq of ¹²³I, ¹²⁵I, and ¹³¹I administered respectively.This work was supported by a research grant from the Veterans Administration