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At least 19 recordsLinked to original sources
PubMed1975

Thallium-201 for myocardial imaging. Relation of thallium-201 to regional myocardial perfusion.

Following intravenous administration, the myocardial concentration of tracer thallium-201, potassium-43, and rubidium-81 were determined in mice; thallium was present in the greatest concentration in the myocardium (2.08% compared 1.25% for potassium and 1.15% for rubidium at 10 minutes). The regional myocardial distribution of thallium-201 was determined in dogs under conditions of normal flow, and total occlusion, and compared with potassium-43 (r=0.97). The regional distribution of thallium-201 was compared to microspheres under conditions of partial occlusion and reactive hyperemia (r=0.97). Thallium-201 was evaluated in a series of phantom scans, which demonstrated that the low energy X-ray of thallium was suitable for imaging. These results suggest that thallium-201 can be used for the evaluation of the distribution of regional myocardial perfusion.

Animals↗
PubMed1977

Kinetic behavior of thallium in the rat. Accelerated elimination of thallium owing to treatment with potent diuretic agents.

1. In acute experiments anesthetized rats were treated with a subthreshold dose of 204Tl+, given intravenously in order to study the elimination kinetics of Tl+. Thallium disappeared from whole blood by means of two different half-lives (5 and 196 min, respectively), whereas VDbeta amounted to 1400 ml. The same kinetic parameters were found after chronic exposure to toxic amounts of Tl+. 2. After chronic exposure to thallium (10 or 30 ppm in the drinking water), the distribution of thallium over various organs proved non-specific. However, a pronounced accumulation was found in the renal medulla. 3. In view of the importance of the renal route in the elimination of Tl+ from the body and also because of the established accumulation of the toxic metal in the kidney, the influence of potent diuretic agents like furosemide and ethacrynic acid on the excretion of Tl+ was studied. The enhanced excretion of water and ions (Na+, K+, Cl-) was accompanied by a significantly accelerated excretion of thallium ions. High doses of ethacrynic acid (25 mg/kg) proved particularly powerful in this respect. Between the enhanced excretion of thallium and potassium ions a significant correlation was obvious, thus supporting the well-known similarity in the behaviour of these ions. The marked increase in renal elimination of thallium upon intensive diuretic treatment may be useful in the management of thallotoxicosis.

Animals↗
PubMed1978

Thallium-205 and proton nuclear magnetic resonance investigation of the complexation of thallium by the ionophores monensin and nigericin.

A thallium-205 and proton nuclear magnetic resonance study of the ionophores monensin and nigericin is reported. Evidence is presented for the simultaneous existence of two forms of monensin free acid in chloroform solution, one containing a water molecule in the central cavity and one with a water molecule on the periphery, linking the ends of the monensin molecule by hydrogen bonding. There appear to be three structurally different monensin complexes of thallium, two in the salt form and one in the acid form. In free nigericin acid, both terminal hydroxyl moieties hydrogen bond to the terminal carboxylic acid oxygens; in the Na+ salt, the binding of one of the carboxylate oxygens to the metal ion allows but one of the terminal OH's to hydrogen bond strongly. Thallium-205 chemical shifts and spin-lattice relaxation times in the title complexes are discussed and compared to those in ionophores studied previously.

Anti-Bacterial Agents↗
PubMed1976

Toxicity and accumulation of thallium in bacteria and yeast.

Thallium sulphate inhibited microbial growth, with Bacillus megaterium KM more sensitive to the metal than Saccharomyces cerevisiae and Escherichia coli. Inhibition of B. megaterium KM and S. cerevisiae, but not of E. coli, was alleviated by increasing the potassium concentration of the medium; inhibition of respiration of S. cerevisiae, but not of E. coli, was similarly alleviated. Thallium was rapidly bound, presumably to cell surfaces, by S. cerevisiae and E. coli, and was progressively accumulated by energy-dependent transport systems (probably concerned primarily with potassium uptake) with both organisms. Thallium uptake kinetics suggested more than one transport system operated in yeast, possibly reflecting a multiplicity of potassium transport systems. Apparent Km and Ki values for competitive inhibition of thallium uptake by potassium indicated S. cerevisiae to have a higher affinity for thallium uptake than for potassium, while E. coli had a transport system with a higher affinity for potassium than for thallium. The likely systems for thallium transport are discussed. A mutant of E. coli with tenfold decreased sensitivity to thallium was isolated and apparently effected surface binding of thallium in amounts equivalent to the wild type organism, but showed no subsequent uptake and accumulation of the metal from buffer, even though it was able to accumulate potassium to normal intracellular concentrations during growth.

Bacillus megaterium↗
PubMedDate not supplied

Thallium loading in owls and other birds of prey in Denmark.

Due to previous findings of increased concentrations of the rodenticid, thallium, in free-living Danish carnivores, thallium analysis has been carried out on material from 77 owls and birds of prey. Thallium was found in 2/3 of the birds and in 10% the concentration was so high that the load of thallium may have caused the death of the birds. The load of thallium in birds of prey was lower than concentrations found in carnivores, probably because poisoning caused by direct intake of thallium baits placed for rodent control does not seem to occur among birds of prey. From the investigation of this limited number of birds, it is not possible to tell if thallium did have any influence on the maintenance of a healthy population of birds of prey, but the large number of thallium loaded birds also justify the restrictions in the sue of thallium which were given from the 1st of July, 1975.

Animals↗
PubMed1975

The cryptonephridial system in the mealworm Tenebrio molitor: transport of radioactive potassium, thallium and sodium; a functional and structural study.

Larvae of the mealworm Tenebrio molitor were injected with radioactive potassium, sodium or thallium solution. It was found that the rectal complex of the animal was labelled with potassium and thallium, but not with sodium. Potassium and thallium labelled the complex to the same level as if the two ions were tracers for each other. Ramsay has found that potassium is actively transported to the complex from the hemocoel and there are reasons to believe that T1+ follows the same pathway. Therefore animals injected with thallium were investigated both by light and electron microscopy. The results suggest that thallium spreads from the hemocoel through the leptophragma to the neighbouring ordinary tubular cells, and in moist mealworms thallium is further found in the perirectal space. Due to diffusion and washing out of thallium during fixation it can not be determined whether T1+ and K+ follow identical pathways, but it is possible to determine how far thallium has penetrated during the experiments.

Animals↗
PubMed1992

Assessing viable myocardium with thallium-201.

Patients with chronic coronary artery disease and potentially reversible left ventricular dysfunction can often be successfully identified by one or more clinical indicators of myocardial viability, including regional wall motion, systolic wall thickening, regional myocardial perfusion as determined by perfusion tracers, and redistribution of thallium-201. In some patients, however, viable but "hibernating" myocardium will exist even when none of the above are evident. Myocardial viability in this situation can be detected with a high degree of accuracy by the demonstration of preserved metabolic activity by positron emission tomography (PET) scanning. Additionally, modifications of the standard exercise-redistribution thallium protocol may also produce accurate results. These modifications include late thallium-201 redistribution imaging, performed 8-72 hours following initial thallium injection, and thallium reinjection at rest after early (3-4 hours) or late (8-72 hours) redistribution imaging. These methods can identify viable myocardium in many thallium defects that appear to be irreversible on a standard 3-4 hour redistribution image. In addition, serial imaging after administration of thallium-201 at rest may also provide valuable insights into myocardial viability. These imaging modalities have important practical applications in the evaluation and management of patients with coronary artery disease and left ventricular dysfunction.

Chronic Disease↗
PubMed1992

Detection of silent coronary artery disease in adolescents and young adults with familial hypercholesterolemia by single-photon emission computed tomography thallium-201 scanning.

Familial hypercholesterolemia (FH), a genetic disease characterized by increased levels of total and low-density lipoprotein cholesterol in the blood, results in a markedly increased incidence of atherosclerosis and coronary artery disease in homozygotes and to a lesser extent in heterozygotes. The purpose of this study was to detect the presence of myocardial ischemia, particularly in heterozygotes, with stress single-photon emission computed tomography thallium-201 scanning and to determine if there were any differentiating variables between heterozygotes with normal and abnormal thallium-201 scans. Fifty-four patients (mean age 16 years; range 8 to 24) with FH were analyzed (4 homozygotes and 50 heterozygotes). Eleven heterozygotes and 3 homozygotes had abnormal thallium-201 scans. Family history, lipid profile, age and sex of heterozygotes with FH did not predict the presence of myocardial ischemia. The mean total cholesterol level in heterozygotes with normal thallium-201 scans was 7.68 +/- 2.29 mmol/liter (297 mg/dl), which was not significantly different from that in heterozygotes with abnormal scans (7.63 +/- 1.07 mmol/liter [295 mg/dl]; p = 0.91). The coronary angiography of 1 homozygote who had an abnormal thallium-201 scan demonstrated a 50% stenosis of the left anterior descending artery. Aggressive, repetitive plasma exchange was then instituted. The 11 heterozygotes with abnormal thallium-201 scans underwent more rigorous dietary and drug therapy. It is concluded that myocardial ischemia with stress in heterozygotes with FH can occur at a young age and that thallium-201 scanning should be performed early as a screening test and to guide patient management.

Adolescent↗
PubMed1992

Prognosis with abnormal thallium images in the absence of significant coronary artery disease.

In the presence of coronary artery disease (CAD), thallium imaging has been reported to add prognostic information that is independent of coronary anatomy. To investigate the prognostic importance of thallium imaging in the absence of significant CAD, 87 patients (65 men, 22 women) with abnormal thallium images without significant CAD were followed for a median duration of 22 months (range 11 to 50). Tomographic thallium images obtained immediately and 4 hours after exercise were interpreted by 2 experienced observers who graded thallium uptake in 24 segments in 3 views (short axis, horizontal long axis, vertical long axis) on a 5-point scale (normal; mildly, moderately, or severely reduced; absent). All patients had an abnormal thallium study, defined as a reversible defect of at least mild severity or a fixed defect of at least moderate severity seen in > or = 2 views, or a combination of these, and a coronary angiogram with stenosis not > or = 70% in diameter narrowing. Eighty-two patients had at least 1 reversible segment, and 26 patients had defects in > or = 2 coronary artery distributions. During follow-up there were no deaths or myocardial infarctions. Coronary angioplasty and bypass surgery were performed in 2 patients. Three-year survival without myocardial infarction or revascularization was 97%. Patients with abnormal thallium images in the absence of significant CAD have an excellent short-term prognosis.

Adult↗
PubMed1978

The effect of Prussian blue and sodium-ethylenediaminetetraacetic acid on the faecal and urinary elimination of thallium by the dog.

After oral administration of sublethal doses of thallium (lower than 10 mg/kg) to dogs, 75.5 +/- 3.9 per cent of the dose was eliminated from the body--47 per cent faecal and 28 per cent urinary. Cumulative excretion reached 50 and 70 per cent after 10 and 25 days respectively, and was almost complete after 75 days. This was slightly lower at higher doses. The total body-burden of thallium, calculated from the cumulative excretion, decreased exponentially for at least the first 40 days with a half-time (T 1/2) of 6.5 days. Oral doses of Prussian blue after 10 days resulted in an acceleration of the thallium elimination from the body (T 1/2 2.5 days), an increase of the faecal (49 per cent) and a decrease of the urinary excretion (18 per cent). Nevertheless, the cumulative faecal and urinary thallium excretion was not influenced. Minor transitory influences of Prussian blue on the faecal thallium excretion could be observed up to day 26. After 40 days, Prussian blue could no longer influence the faecal thallium excretion. At no time did sodium-ethylenediaminetetraacetic (Na2EDTA) acid significantly change faecal or urinary thallium excretion.

Administration, Oral↗
PubMed1992

Myocardial hibernation identified by hyperbaric oxygen treatment and echocardiography in postinfarction patients: comparison with exercise thallium scintigraphy.

To evaluate the potential for hyperbaric oxygen (HBO) to produce transient improvement in function in areas of myocardium ischemic at rest (hibernating myocardium), 24 patients were studied within 1 week of acute myocardial infarction. Results were compared with single-photon emission computed tomography (SPECT) thallium-201 exercise scintigraphy. Echocardiography demonstrated improved contraction following HBO in 20 of 62 damaged left ventricular segments in 12 of 24 patients. Thirteen of the 28 segments and 9 of the 14 patients showing reversible ischemia on SPECT imaging showed improvement with HBO. There were eight segments with apparently normal resting contraction that showed a reversible thallium defect. Of 42 segments with fixed contraction abnormalities following HBO, eight had reversible thallium defects, four had normal thallium kinetics, and 30 had fixed thallium defects. Thus hyperbaric oxygen can demonstrate improvement in function in some segments of left ventricle after infarction. There is some overlap with viability as determined by thallium studies, but the two techniques may be complementary in describing myocardial ischemia.

Adult↗
PubMed1992

Prediction of late cardiac events by dipyridamole thallium imaging in patients undergoing elective vascular surgery.

Dipyridamole thallium scintigraphy has previously been shown to have prognostic value in the preoperative assessment of patients scheduled to undergo vascular surgery, but its effect on the long-term outcome is less well-defined. In the largest series to date, dipyridamole thallium scanning was performed in 360 patients before elective vascular surgery and survivors were followed for a mean of 31 months. In the 327 patients who underwent vascular surgery, operative death and nonfatal myocardial infarction occurred in 4.9 and 6.7%, respectively. A cardiac event (nonfatal myocardial infarction or cardiac death) occurred in 14.4% of patients with a transient thallium defect, as opposed to 1% with a normal scan (p < 0.001). Logistic regression analysis revealed that the best predictor of a perioperative event was the presence of a reversible thallium defect, elevating the risk by 4.3-fold. Late cardiac events occurred in 53 (15.2%) surgical survivors or nonsurgically treated patients. Patients with a fixed perfusion abnormality had a 24% late event rate, compared with 4.9% in those with a normal dipyridamole thallium study (p < 0.01). Cox analysis demonstrated that a fixed thallium defect was the strongest factor for predicting a late event and increased the relative risk by almost fivefold. A history of congestive heart failure was the only significant variable that contributed additional value to that of a fixed defect alone. Life-table analysis confirmed the strong relation of a fixed defect to cardiac event free survival (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Comparison of technetium-99m sestamibi and thallium-201 retention characteristics in canine myocardium.

OBJECTIVES: The aim of this study was to compare the myocardial retention of technetium-99m (Tc-99m) sestamibi and thallium-201 over a wide range of blood flow at different time points after tracer injection. BACKGROUND: Technetium-99m sestamibi has been proposed as a new perfusion tracer with better physical characteristics than those of thallium-201 for scintigraphic imaging. However, no studies have simultaneously compared the ability of both tracers to assess myocardial blood flow during pharmacologic vasodilation. METHODS: The myocardial retention of Tc-99m sestamibi and thallium-201 were compared over a wide range of blood flow induced by regional coronary occlusion and dipyridamole infusion in an open chest dog model. Myocardial retention of both tracers was determined by in vitro tissue counting at 2, 5, and 20 min after tracer injection and was correlated with microsphere-determined blood flow. RESULTS: Thallium-201 demonstrated greater absolute tissue retention than did Tc-99m sestamibi. At 2 min after tracer injection, there was an almost linear relation between the retention of both tracers and myocardial blood flow over a wide flow range. However, this relation was not maintained over time. At 20 min after injection, the retention of both tracers underestimated myocardial blood flow at higher flow rates. At 2, 5 and 20 min after injection, increments of relative tracer retention between the different levels of flow were always greater for thallium-201 than for Tc-99m sestamibi. CONCLUSIONS: Thallium-201 displays more suitable physiologic characteristics as a flow tracer and may allow better differentiation of myocardial regions with different levels of coronary flow reserve. For both tracers, early cardiac imaging may minimize underestimation of blood flow at higher flow rates.

Animals↗
PubMed1978

[On heavy-metal poisoning, especially by thallium (author's transl)].

Only thallium poisoning is still of clinical significance among heavy-metal intoxications. Among 1800 cases of poisoning there were 15 caused by thallium, 3 by lead and 1 by iron (none by arsenic or mercury). Among thallium poisonings, 13 were due to suicide, one ending fatally, and two of homicide. Thallium can be demonstrated in urine even after haemodialysis and forced diuresis. As more and more rat poisons contain coumarine derivatives instead of thallium, the number of cases of thallium poisoning is likely to decrease.

Adolescent↗
PubMed1979

Serial exercise thallium myocardial perfusion scanning and exercise electrocardiography in the diagnosis of coronary artery disease.

Serial exercise thallium-201 myocardial perfusion scanning (exercise and 4-hour redistribution) was compared to rest and exercise electrocardiography (ECG) for the detection of coronary artery disease in 125 patients with known or suspected coronary artery disease. All patients underwent coronary arteriography and 108 were found to have significant coronary artery lesions. The serial exercise thallium scan was significantly more sensitive than rest and exercise ECG in detecting coronary artery disease (94% v. 83% P less than 0.01). The sensitivity of a reversible thallium perfusion scan abnormality and a positive exercise ECG for detecting exercise induced myocardial ischaemia in coronary artery disease was similar (69% v. 63%). The exercise thallium scan complemented the exercise ECG, and the sensitivity of the combined test was significantly greater than the exercise ECG alone (84% v. 63% P less than 0.001). The specificity for coronary artery disease of the exercise ECG was 65% and that of the exercise thallium-201 myocardial perfusion scan was 82% (P = NS). Thallium-201 myocardial perfusion scanning complements the rest and exercise ECG in the non-invasive detection of coronary artery disease.

Adult↗
PubMed1976

[Thallium intoxication treated by hemodialysis, forced diuresis and antidote (author's transl)].

Mode of action and toxicity of thallium and former treatment of thallium intoxication are described. A case of thallium poisoning with a lethal dose of thallous sulfate which was successfully treated by hemodialysis, forced diuresis and antidote is reported. 43 percent of the thallium could be eliminated by continuous hemodialysis during 72 hours and forced diuresis within the third and seventh day after ingestion of the poison. The dialysance of thallium was 111,1 ml/min with a blood flow of 200 ml/min. Later damage can be prevented by early maximal elimination of thallium.

Adenosine Triphosphatases↗
PubMed1979

Thallium as an industrial poison (review of literature).

The presented reports on cases of occupational thallium poisoning clearly demonstrate that the possibility of their occurrence in industrial plants is very real. The number of such intoxications is much higher than that of non-industrial poisonings, but this is predominantly due to the less pronounced clinical picture and to the fact that specific tests for thallium are not performed. As a result, these cases partly escape registration altogether and partly are wrongly diagnosed. Thallium and its compounds belong to the first class of poisons, their dangerousness being enhanced by their easy permeability through the skin. Industrial thallium poisoning can be either acute or chronic, but in all cases, it is characterized by a long duration and severity of its course. Strict hygienic demands on the organization of the technological process and the measures of protection of persons working with thallium are indispensable. Compulsory examination of the urine of those working with thallium for the presence of this substance should also be introduced.

Adult↗