Distribution Of Thallium Research Articles

Preliminary report on high thoracic epidural analgesia: Relationship between its therapeutic effects and myocardial blood flow as assessed by stress thallium distribution

Objectives: To extend the duration of high thoracic epidural analgesia (HTEA) treatment compared with the authors' previous studies, to test the hypothesis that the mechanism by which HTEA reduces angina during long-term treatment includes an improvement in myocardial blood flow distribution and a reduction in stress-induced ischemia, and to show that new myocardial infarctions are not masked or missed in patients receiving HTEA. Design: Prospective consecutive study. Setting: Department of Veteran's Affairs medical center and university-affiliated hospital. Participants: Six consenting adult patients. Interventions: Patients were evaluated before HTEA catheter insertion and >2 months after HTEA catheter insertion with stress thallium tests. Measurements and Main Results: Two of 6 patients had improvement but not resolution of stress-induced ischemia at 8 and 12 months. The remaining 4 patients had no change in stress-induced ischemia. None of the 6 patients had any new areas of ischemia or infarction as determined by stress thallium tests. Conclusions: The authors previously showed that HTEA is safe and effective in relieving refractory angina pectoris. The current study shows that this therapeutic effect persists and does not appear to be related to a change in myocardial blood flow; rather the improvement in symptoms probably results, in part, from an anesthetic effect. HTEA does not mask the development of new myocardial infarctions. Copyright © 2000 by W.B. Saunders Company

Studies on thallium toxicity, its tissue distribution and histopathological effects in rats

The distribution of thallium (Tl) in the body and its toxic effect on the histology and function of the liver and kidney of rats after Tl administration were investigated using biochemical and histopathological assays. Male albino rats exhibited a markedly dose-dependent increase in the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) at 16 h after an intraperitoneal injection of 30, 60 or 120 mg/kg Tl. The serum level of creatinine in the rats injected with 30 mg/kg Tl, elevated significantly after 4 days of administration. The distribution of Tl in the tissues of intoxicated rats was uneven. The content of Tl was found to be highest in the kidney, followed by ileum, stomach and liver. Histological examination demonstrated frequent occurrence of hepatocyte necrosis and vacuolation in the liver and pathological changes of renal tubules in the treated rats.

Thallium Speciation in the Great Lakes

An ion-exchange separation technique followed by analysis with atomic absorption spectroscopy was used to study the chemical forms and distribution of thallium in Lakes Michigan, Huron, and Erie. The dominant thallium form found in water samples analyzed was the oxidized Tl(III) which comprised 68 ± 6% of the total dissolved thallium, contrary to thermodynamic prediction that Tl(I) is favored in natural waters. A significant proportion of Tl(III) may be in colloidal form. No definite spatial (horizontal or vertical) pattern was found in the distribution of total dissolved thallium in the water columns of Lakes Michigan, Huron, and Erie. An overall decline of thallium concentration from Lake Michigan to Lake Erie was observed which may be related to rapid scavenging removal from the water column.

P2F176 - Acute thallium poisoning and its treatment with two cases report

The distribution of thallium (Tl) in the body and its toxic effect on the histology and function of the liver and kidney of rats after Tl administration were investigated using biochemical and histopathological assays. Male albino rats exhibited a markedly dose-dependent increase in the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) at 16 h after an intraperitoneal injection of 30, 60 or 120 mg/kg Tl. The serum level of creatinine in the rats injected with 30 mg/kg Tl, elevated significantly after 4 days of administration. The distribution of Tl in the tissues of intoxicated rats was uneven. The content of Tl was found to be highest in the kidney, followed by ileum, stomach and liver. Histological examination demonstrated frequent occurrence of hepatocyte necrosis and vacuolation in the liver and pathological changes of renal tubules in the treated rats.

Subcellular distribution of thallium: morphological and quantitative study in rat myocardium.

The purpose of this study is to determine the subcellular distribution of thallium (SDTl) by electron microscopy and a newly designed fixation method that makes insoluble grains of Tl visible. To obtain the high dose necessary for electron microscopic visualization, we employed TlCl instead of 201TlCl. EM was performed in fixed rat myocardium resected at 20 min (early phase) and 3 hr (delay phase) after intravenous injection of TlCl. To fix Tl in the cell, we used orthovanadate in our fixative. Atomic absorption spectroscopy (AAS) of Tl and quantification of subcellular distribution of 201Tl (SD201Tl) were studied to prove the propriety of our fixation. AAS detected Tl in the Tl-loaded specimen but not in the control, indicating that Tl was the origin of the grains observed in the former. In the early phase, numerous grains were observed in mitochondria, sarcoplasmic reticulum (SR), myofibrils, and nuclei, but no such grains were visible in controls. In the delay phase, grains were retained in mitochondria, SR and nuclei, but not in myofibrils. Electron microscopic SDTl(%) correlated with SD201Tl(%) calculated from isolated fractions. In both the early and delay phases, mitochondria are the major site of Tl and 201Tl uptake.

Can T1-201 myocardial SPECT abnormalities in orthotopic heart recipients be explained by coronary vessel wall alterations assessed by intravascular ultrasound?

The aim of this study was to compare findings on coronary intravascular ultrasound and thallium-201 SPECT in patients following orthotopic heart transplantation. Background: No data are available on whether pathological thallium scintigraphic findings in heart recipients are based on coronary vessel wall alterations identifiable by intravascular ultrasound. Methods: 29 patients (mean age: 50.9 ± 11.5 years; male n = 23) were investigated by means of intravascular ultrasound of selected coronary segments and thallium-201 myocardial SPECT. Patients were investigated 11.6 ± 5.4 weeks post transplantation, a subgroup of 13 patients was re-investigated 70.2 ± 18.4 weeks following transplantation. A total of 214 cross-sectional areas of the left coronary artery were examined using a 3.5 French intravascular ultrasound catheter to measure intimai index and the circumferential extension of a three-layer appearance of the vessel wall. Shortly after catheterisation, an ergometric stress-test was performed to examine all recipients by means of thallium-201 SPECT. In each patient, 20 segments of the left ventricle were evaluated using a score system to differentiate between persistent defects, redistribution, and reverse redistribution. A score was developed that measured the degree of inhomogeneity and severity of perfusion defects, respectively. Findings on scintigraphy were correlated to coronary intravascular ultrasound findings. Results: At first investigation, mean intimai index of all evaluated coronary cross-sectional areas was 0.06 ± 0.1. Sixty-four cross-sectional areas demonstrated a three-layer appearance of the vessel wall, mean circumferential extension was 72 ± 122 degrees. Thallium scintigraphy demonstrated a total of 336 (40%) pathological left ventricular segments; 168 (20%) were regarded as permanent defects, 67 (8%) demonstrated redistribution and 101 (12%) showed reverse redistribution. The score of inhomogeneity was calculated as 5.8%±2.6%. In the subgroup of patients at the follow-up study, the score was 6.4±2.8%. There was no correlation between intimai index and the score, nor could any correlation be confirmed between the score and the circumferential extension of a three-layer appearance of the vessel wall. At second investigation, no significant differences of intimai index (0.05±0.07) or circumferential extension of a three-layer appearance of the vessel wall (74±118 degrees) could be confirmed. The score was slightly, but significantly increased to 8.1 ± 4.5% at the second investigation ( P < 0.05). Conclusion: Early after orthotopic heart transplantation, pathologic thallium distribution patterns of the left ventricle could be observed. These pathological patterns did not correlate with the extent of diffuse coronary vessel wall alterations identifiable by intravascular ultrasound. After more than 1 year, the degree of scintigraphic abnormalities increased significantly, not accompanied by an increase of diffuse coronary vessel wall alterations.

CALF BLOOD FLOW AS A NON-INVASIVE PREDICTOR OF LIMB PERFUSION IN PERIPHERAL ARTERIAL DISEASE 1170

A thallium graded exercise test (GXT) has been used to access lower limb perfusion in peripheral arterial disease (PAD) patients; however, this test is an invasive and costly procedure. Therefore, the purpose was to see if a less costly, non-invasive measure of calf perfusion would correlate with the more invasive thallium procedure. Eighteen PAD patients with a resting ankle/brachial systolic pressure index (ABI) of 0.60 ± 0.15 (Mean± SD) were recruited. All subjects underwent a GXT on a treadmill to maximum leg pain tolerance. Thallium was injected during the final minute of the GXT and then the lower extremities were scanned for thallium distribution. Peak calf blood flow (PCBF) was measured non-invasively by having the subjects perform toe raises to pain tolerance while leg blood flow was occluded with a thigh cuff. PCBF measurements were taken at 1 and 3 min post occlusion. A thallium index (ThI) was calculated as a ratio of the total count of calf area/gluteal area of the more severely diseased leg. The ThI for the group was 0.40 ± 0.13. The PCBF were 11.99 ± 4.84 ml/100 ml/min and 10.77± 3.81 ml/100 ml/min for the 1 and 3 minutes post, respectively. A lower ThI was related to lower PCBF at both 1 min (r=0.50, p<0.05) and 3 min (r=0.50, p<0.05) post occlusive exercise. It is concluded that PCBF is a valid predictor of lower limb perfusion in PAD patients.

Thallium distribution in organs and brain regions of developing rats

The concentration of thallium in body organs and brain regions was studied in rats as a function of the animals age from newborn to 20-days old. Thallium was analyzed at different times after a single sublethal i.p. injection of the metal (16 mg/kg). The results indicate that the brain is less permeable to thallium in the older animals, suggesting that reduced thallium transport into the brain is related to the establishment of the blood-brain barrier in the rats. Differences between weanling and newborn rats were also found in regard to regional distribution of thallium in the brain as the older animals showed a region-dependent distribution while newborn rats presented an homogeneous content of thallium among all regions.

Mechanism and significance of precordial ST-segment depression during inferior wall acute myocardial infarction associated with severe narrowing of the dominant right coronary artery

The mechanism and significance of precordial ST depression during inferior wall acute myocardial infarction (AMI) is debated. This study assessed the location and extent of arterial perfusion distribution responsible for this electrocardiographic finding. Intracoronary thallium-201 was injected in 11 patients with 1-vessel right coronary disease to delineate perfusion distribution that was quantitated by a new angiographic distribution score. The angiographic score correlated with posterior (r = 0.84), posterolateral (r = 0.88) and total (r = 0.73) extent of intracoronary thallium distribution. The angiographic distribution score was related to electrocardiographic changes in 16 patients showing an inferior ST-segment elevation during angioplasty (7 with and 9 without precordial ST depression), of which 6 received intracoronary thallium injection. None had thallium distribution in the anterior or septal segment, but there was a trend toward a greater angiographic distribution score and posterior segment thallium score in patients with precordial ST depression. In another 77 patients with inferior wall AMI due to right coronary occlusion (24 with concomitant left anterior descending narrowing), precordial ST depression was present in 16 with and 31 without left anterior descending narrowing (p = NS). The angiographic distribution score was higher in those with than without precordial ST depression (0.59 ± 0.10 vs 0.44 ± 0.11, p < 0.001) in both patients with and without left anterior descending disease. The magnitude of both inferior ST elevation and precordial ST depression correlated with the angiographic distribution score, but only precordial ST depression was independently related in multivariate analysis. Precordial ST depression during inferior wall AMI indicates a larger extent of posterolateral and total perfusion of the infarct-related artery independent of the presence or absence of left anterior descending narrowing, and identifies a subgroup who may derive greater benefit from reperfusion.

A new method for evaluating lung uptake of thallium-201 during stress myocardial scintigraphy.

A novel, multipurpose device has been designed that allows thallium activity to be continuously studied from a given lung area at rest and at peak exercise. The information gained from this technique proves to be relevant and reliable because lung thallium activity is displayed in real time and the interpretation of thallium distribution is not based on qualitative or quantitative comparison with that in the myocardium or mediastinum. The time-activity curves obtained in our study group are reported and the relation of peak activity to plateau activity (peak/plateau ratio) is proposed as an index that is easy to obtain for identifying patients with normal and impaired left ventricular function.

Accumulated forms of thallium and cadmium inLemna minor. I. Distribution in aqueous soluble and insoluble fractions

The distribution and chemical forms of thallium (Tl) and cadmium (Cd) in Lemna minor have been investigated using extractants of different polarity, enzyme digestion and ultrafiltration and chromatographic methods. Over 80% of Tl and 60% of Cd taken up by the plant was found in aqueous soluble forms. Water was more efficient than ethanol in extracting both elements; about 30% of bound Cd was released by dilute HCI treatment and Cd was mainly bound to pectins and proteins in the cell wall fractions but only a small proportion of Tl was associated with these components. In the aqueous soluble extracts a sizeable proportion of Cd was complexed with soluble moieties, including proteins; whereas Tl seems to be mainly present in the free ionic form.

A NEW 50 K SUPERCONDUCTOR, Tl1+xBa2−x−yLayCuO5−δ, FIRST MEMBER OF THE SERIES TlA2Cam−1CumO2m+3

New superconductors Tl 1+x Ba 2−x−y La y CuO 5−δ(x = 0, y = 0.6 and x = 0.25, y = 0.75) have been isolated, which exhibit a zero resistance below 50 K and a diamagnetic fraction volume ranging from 7% to 35%. Their tetragonal structure corresponds to the intergrowth of single perovskite layers with double rock-salt type layers. These latter slabs exhibit two original features, presence of oxygen vacancies and distribution of thallium over two sorts of sites. This particular behavior is discussed in terms of mixed valence of thallium, Tl(I)/Tl(III) taking into account the 6s2 lone pair of T1(I).

Distribution and excretion of thallium after oral and intraperitoneal administration of thallous malonate and thallous sulfate in hamsters.

Distribution and excretion of thallium after oral and intraperitoneal administration of thallous malonate and thallous sulfate in hamsters.

Brain regional thallium distribution in rats acutely intoxicated with Tl2SO4.

The content of thallium in seven body organs and eight brain regions of rats acutely exposed to Tl2SO4 was compared. Rats received a single i.p. injection of Tl2SO4 at three doses: 16, 32 and 48 mg/kg. At 24 h after treatment, thallium content in kidney was higher than in all other organs studied and whole brain had the lowest thallium concentration. A thallium differential distribution was found among brain regions. The highest thallium concentration was found in the hypothalamus and the lowest in the cortex. This distribution pattern was similar with the three doses used. Time course of thallium accumulation in brain was found to be considerably more rapid in the hypothalamus than in other regions, particularly the cortex, suggesting differences in thallium entry into brain parenchyma. Thallium brain regional differential distribution might be related to some of the symptoms of thallium central neurotoxicity.

Underestimation of Residual Ischemia by 201-Thallium Scintigraphy after Myocardial Infarction

Pre- and post-CABG perfusion scintigraphic findings are reported in a patient with residual ischemia after anterior myocardial infarction. The preoperative 201Tl scan showed incomplete tracer redistribution and a relevant area of persistent irreversible defect, suggestive of a large scar. After CABG, the presence of a virtually normal early thallium distribution demonstrated previous underestimation of the viable perinecrotic tissue. A persistent perfusion defect, even if associated with wall motion abnormality, does not necessarily imply the absence of residual viable tissue.

The Influence of Trace Elements on Environment; Distribution of Thallium in Fluids of Volcanic Areas

Abstract During weathering of igneous rocks thallium can be readily mobilized as TI+ in aqueous phase and picked up by plants. In this way it can reach the alimentary cycle of both livestock and humans. Since the toxicity of thallium is well-established, an analytical procedure for its determination is optimized in order to contribute to the knowledge of TI+ distribution in specific environments. The analytical method is applied to fluid phase samples from Vulcano island (Italy) and from other volcanic areas.

Parametric images as a tool for quantitative normative evaluation

Features extracted from static or dynamic scintigraphic images can be used to produce parametric or functional images. Those images typically map a dynamic parameter (temporal encoding) or a quantitative measure of the tracer distribution. In this report, we consider the cases in which the nature of the extracted feature is well suited for a quantitative normative evaluation, ie, where the values obtained can be directly or indirectly compared with expected normal values. The major difference between this approach and the more common heuristic or synoptic interpretation of "images" lies in the underlying modeling: the model "predicts" a minimal washout rate, a match between ventilation and perfusion rates in the lungs, homogeneous contraction in the left ventricle, an expected angular distribution of thallium in the myocardium, or the absence of an additional kinetic feature. The quantitative aspect of the analysis is based in all cases on an approach that overcomes or is less sensitive to morphological or structural biological variability: in some cases the patient provides the normalizing data, as in ventilation-perfusion ratios. In other cases, the model predicts homogeneous results (as in phase analysis) or a range of normal physiological values (for xenon washout). Less commonly, the analysis requires a transformation of the data, as is the case in the analysis of myocardial perfusion, which follows a polar transformation of the image, and an analysis based on angular coordinates. In a normative approach, pathology is defined as a deviation (in this case a quantitative deviation) from the norm. The next step is to model specific abnormalities: early right-sided reappearance of the bolus in a right-to-left shunt, the appearance of "abnormal" kinetic factors, or a comparison with the expected distribution of bloodflow (or location of defects) in certain coronary lesions. However, in all cases, one should note that the analysis does not compromise the major feature of "imaging," that is to recognize regional, rather than exclusively global malfunction.

Surgery and Prognosis in Coronary Heart Disease

Coronary artery bypass surgery relieves angina by improving the blood supply to territories supplied by blocked or narrowed arteries and it is generally agreed to be highly effective [1—5]. Medical treatment reduces angina by increasing the efficiency of the heart and reducing demand but it is much less successful than surgery in relieving symptoms and does little to improve the defective blood supply. It has been shown that coronary bypass relieves angina by correcting ischaemia and not for any other reason. Comparing the effects of exercise on ST-segment depression and thallium distribution or exercise provoked regional left ventricular akinesia, nuclear blood pool imaging before and after surgery shows that after surgery evidence of ischaemia can no longer be elicited frequently by any test. Unfortunately atherosclerosis is a progressive disease and later deterioration may relate both to the development of new lesions in ungrafted arteries and to narrowing or occlusion of grafts both of which are unfavourably influenced by high plasma lipid levels [6-9]. Use of the internal mammary artery may greatly improve the longevity of grafts to the important anterior descending artery coronary artery system. Death from coronary heart disease is related indisputably to the blocked arteries so that restoration of regional blood flow would be expected to improve prognosis as well as to relieve symptoms. It is surprising that these benefits of coronary surgery are still disputed [8, 9]. The last 20 years has seen a steady decline in the reported mortality of coronary heart disease in the United States and in some other countries [10,11]. If true this could be explained either by a reduction in incidence or by extended survival in those with the disease or by a combination of each. The earliest observations on medical prognosis with known coronary artery anatomy and left ventricular function were made before beta-blocking drugs or calcium antagonists were available and the annual mortality rate in patients with 'three vessel' coronary artery obstruction has fallen from 11.4 per cent in the late 1960s [12] to 4.8 per cent [13] and 3.5 per cent [14] through the 1970s down to only 2.1 per cent in the most recently reported American Coronary Artery Surgery Study (CASS) [15]. Comparable improvements in prognosis have occurred among other categories of patients, angiographically defined, and this is attributable to medical treatment as well as to changes in referral practice. Randomised studies of effects of surgery on prognosis necessarily take many years to provide answers and during those years surgical techniques improve and patients deteriorate. This requires cross-over of randomised patients from medical to surgical treatment for the relief of compelling symptoms thereby ruining the

Assessment of regional myocardial perfusion with thallium imaging during transient left anterior descending coronary arterial occlusion during angioplasty

To define the jeopardized territory perfused through a single coronary arterial stenosis, thallium-201, 2 mCi, was injected into the pulmonary artery at the onset of the last of a series of percutaneous transluminal coronary angioplasty (PTCA) balloon inflations in 10 patients with single-vessel left anterior descending coronary artery disease. Imaging was begun immediately after PTCA. Arterial thallium activity peaked 30 seconds after injection and decreased to 34 ± 6% (mean ± standard error of the mean) of peak activity at the time of balloon deflation. Regional thallium activity during exercise vs PTCA was scored qualitatively and quantitatively. A computer quantification program was used that permitted automatic realignment and normalization of the 2 initial thallium images. Only mean quantitative posterior activity was lower (93 ± 1% vs 86 ± 2%, p < 0.05) on exercise scans compared with PTCA scans. The other 5 segments showed no difference in mean scores. There were no qualitative differences in initial thallium distribution, nor were there qualitative or quantitative differences in the number of abnormal segments or severity of reduction in activity in the segment with the lowest activity. In conclusion, regional thallium myocardial distribution with a single severe stenoses with injection during peak exercise is similar to that after complete coronary occlusion.

Thallium myocardial perfusion scintigraphy: influence of perfusion, scatter, and photon energy on the detection of lesions.

Experimental studies have been made of lesion detectability in myocardial perfusion studies using thallium-201. A series of images (AP view) was generated mathematically. Images were simulated with 100k, 200k, and 300k counts for the complete image and either non- or half-perfused lesions (lesion volume 1-6 1/2% of total myocardial volume). In addition thallium images were generated excluding scatter; images were also generated with a radiopharmaceutical using 140, 184 and 296 keV, assuming the biological distribution of thallium. All images were interpreted by seven observers. Count density did not affect the true-positive fraction of the interpretations. However, the false-positive fraction decreased significantly when count density increased. Lesions located far from the camera were detected worst. The intraobserved variability was largest for interpretation of these regions. Small lesions were poorly detected. Perfusion of lesions significantly affected their detection, independent of the count density, lesion volume, and lesion location. Scatter did not affect the detection of lesions. No significant difference was found when the performance of the observers was compared for 80 keV and 140 keV. The use of 184-keV and 296-keV photons resulted in a lower detection rate probably because of the use of a high energy collimator.