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  • 1
    ISSN: 1432-2307
    Keywords: Experimental thrombus organisation ; Mononuclear cell ; Mesenchymal transformation ; Mesenchymal cell ; Myofibroblastic cell ; Endothelial cell ; Dualistic genesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To clarify whether thrombus organisation was carried out by local cell activity or by elements of the circulating blood we developed an artifical prosthesis, made of an impermeable polyurethane material with an athrombogenic surface but with a central part consisting of a DACRON velour ring which was thrombogenic. We implanted these devices into the aorta of 10 sheep. In these animals, organisation of the central thrombus by local aortic cells could be excluded. After varying periods of time (2–84 days), the device was removed and the organized thrombus investigated by light and electron microscopy. From our investigations the organisation process with the development of mesenchymal cellular elements proceeded in 3 steps: (1) The activation of the mononuclear macrophage system (2), the appearance of myofibroblastic cells and (3) endothelial formation. The activation of the mononuclear macrophage system is probably induced by chemospecific products of metabolism arising from aging thrombotic material. Apart from mononuclear elements such as monocytes, macrophages, and giant cells we observed fibroblast-like and myofibroblast-like cells. The matrix contained collagen. Endothelium developed on the surface of the organizing thrombus. The final stage was characterized by the formation of a pseudovessel wall, which followed the pattern of the vascular model. Our findings support the hypothesis that a thrombus may be organized by cells derived from the circulating blood.
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  • 2
    ISSN: 1432-0851
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During previous therapeutic trials with interferon, decreased levels of peripheral platelet counts have been observed. Taking advantage of this effect, we investigated the efficacy of recombinant interferon (rec-IFN) in the treatment of thrombocytosis in myeloproliferative diseases. A total of 15 patients with polycythemia vera, essential thrombocytosis, or chronic myeloid leukemia received rec-IFN-alfa at initial doses of 25–70×106 units/week; maintenance therapy following week 8 of treatment consisted of 20–35×106 units/week rec-IFN. Observation periods ranged from 24 to 48 weeks. Significant reductions in the number of platelets were noted in all cases; 12/15 patients achieved platelet counts below 440×109/1 and maintained those normal values for at least 4 weeks. The number of bone marrow megakaryocytes, which had been increased prior to treatment, diminished during rec-IFN therapy, while the previously shortened platelet half-life further decreased with rec-IFN treatment. During rec-IFN-induced remission, the plasma levels of platelet factors, the activity of natural killer cells, and platelet aggregation showed changes between slight improvement and normal values. Severe side effects were only observed with the highest rec-IFN doses; dosage adjustments were effective in improving or eliminating all treatment-related symptoms. Rec-IFN may prove to be a valuable therapeutic alternative to cytostatic treatment of thrombocytosis in myeloproliferative disorders.
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  • 3
    ISSN: 1619-7089
    Keywords: Key words: Adsorption of radioactivity ; Technetium-99m tetrofosmin ; Technetium-99m furifosmin ; Radiopharmaceuticals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Some groups have reported that adsorption of radiopharmaceuticals on disposable plastic syringes can reach levels of almost 50%. This high loss of radioactivity stimulated us to carry out similar studies. Our measurements were done in combination with patient studies. Therefore, we used 2-ml syringes, all of the same brand. The radioactivity in the syringe was measured immediately before and after injection. a total of 500–600 MBq technetium-99m labelled tetrofosmin or technetium-99m furifosmin was administered to 48 patients using four different injection techniques (n = 6 for each technique with each tracer): with needles, 1 min blood incubation at 22°C, 10 or 30 min after preparation of the tracer; with butterflies, 1 min blood incubation at 22°C, 10 or 30 min after preparation of the tracer. Neither in syringes nor in needles or butterflies did more than 7% of the initial radioactivity remain. The entire residual activity in syringe plus needle or syringe plus butterfly together never exceeded the 9% limit. Furthermore, in a pilot study we measured the remaining radioactivity in the vial; here, too, we found no more than 14% of total radioactivity. These findings indicate that total retention of radioactivity during elution and application of 99mTc-tetrofosmin and 99mTc-furifosmin with material used in our setting does not approach relevant amounts.
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  • 4
  • 5
    ISSN: 1615-5939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although active smoking is known to enhance platelet thromboxane production, no data on passive smoking are available yet. In an 18 m3 room, the influence of single and repeated exposure to passive smoke for 60 minutes was assessed in nonsmokers and smokers. Smokers and nonsmokers were matched for sex and age. All the evaluated parameters (plasma TXB2, serum TXB2, malondialdehyde, 11-dehydro-TXB2, conversion of exogenous arachidonic acid to hydroxy-5,8,10-heptadecatrienoic acid, and TXB2) were higher in smokers than nonsmokers at baseline conditions, immediately and 6 hours after passive exposure to cigarette smoke. Repeated exposure of nonsmokers rendered their platelets more activated, so they became closer to the behavior of smokers. Contributing to the development of hemostatic imbalance, these results indicate that passive smoking may enhance thromboxane A2 release from the platelets.
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  • 6
    ISSN: 1615-5939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is a strong need to directly image, noninvasively, atheromatous lesions for early lesion detection, serial assessment of the presence and extent of disease, and treatment monitoring of atherosclerosis. The aim of this study was to investigate the value of polyclonal111Inhuman IgG (111In-HIG) in human carotid artery disease. A comparative study between111In-HIG and125I-LDL uptake in atheromatous lesions was also performed in 12 cholesterol-fed New Zealand white rabbits. Ultrasonographic and scintigraphic findings in 58 patients were compared. HIG was labeled with 500 µCi111Indium by the diethyleneaminepentaacetic anhydride (DTPA). After injection of 10 µCi125I-LDL, the respective entry into aortic segments was evaluated in the animals.111In-HIG accumulation was higher in reendothelialized areas, foam cells, at the edge of lesions, and in hyperlipidemic rabbits. Ultrasound examinations of the carotid arterial wall showed wall thickening in 45 patients and plaques in 44 patients. Scintigraphic imaging of the identical area provided increased uptake in 40 patients and no abnormal uptake of111In-HIG in 18 patients. There was, however, no significant correlation between the radiotracer retention and the ultrasonographic findings or laboratory and clinical parameters. The data provide evidence that the two imaging techniques for early atherosclerotic lesions are visualizing different aspects of atherogenesis: the functional (HIG) on the one side, and the morphological (ultrasonography) on the other side.
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  • 7
    ISSN: 1619-7089
    Keywords: Key words: Iodine-123 metaiodobenzylguanidine – Myocardial uptake – Rabbit myocardium – Uptake mechanism – Drug influence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. About 15 years ago, iodine-123 metaiodobenzylguanidine (MIBG) myocardial imaging was introduced for the evaluation of myocardial sympathetic nerve function. Two uptake mechanisms for MIBG have so far been identified: uptake type I, a saturable, energy-dependent mechanism, and uptake type II, a non-saturable, energy-independent mechanism. We incubated isolated rabbit myocardial tissue samples with 123I-MIBG in order to assess the uptake characteristics and the influence of varying incubation conditions. Furthermore, we examined the effects of several drugs and uptake inhibitors on the myocardial uptake of MIBG. The in vitro myocardial uptake of MIBG reached a steady plateau at 23.87%±3.63% after 1 h, i.e. a concentration gradient of 10, in a thermo-independent manner within a concentration range from 1.5 to 1500 µM. This indicates an unsaturable uptake process in the tested concentrations. Pre-incubation with the following drugs caused a significant inhibitory effect on myocardial MIBG uptake: haloperidol, levomepromazine, metoprolol, labetalol and clomipramine. According to our findings, the uptake mechanism seems to be an unspecific process, but the concentration gradient of 10 makes passive diffusion unlikely. Further studies with uptake-II-blocking substances as well as with isolated myocardial cells will be needed to clarify the nature of the myocardial MIBG uptake mechanism.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 17 (1990), S. 160-178 
    ISSN: 1619-7089
    Keywords: Atherosclerosis ; Platelets ; Monocytes ; Low-density lipoproteins ; Fibrinogen ; Fibronectin ; Porphyrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although the pathomechanisms of atherosclerosis are well known, their radioisotopic monitoring is still in its early childhood. The current radioisotope techniques are of only limited value for contributing to the clinical diagnosis of atherosclerosis. The limited reaction time of cellular blood constituents (platelets, monocytes) with the vascular surface at the injury site makes it very difficult to catch the point of injury. Lipoproteins excellently allow receptor imaging, while vascular monitoring is only of scientific interest at present. Labelling and subsequent imaging of components of the coagulation cascade have not succeeded so far, nor have attempts using unspecific labels such as porphyrin, polyclonal IgG and Fc fragments, for example. Preliminary evidence indicates that radioisotopic techniques may be of great benefit in the future in elucidating functional aspects of the disease, while they do not contribute to examining the stage and extent of atherosclerosis.
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  • 9
    ISSN: 1619-7089
    Keywords: 99mTc-MIBI 99mTc-tetrofosmin 99mTc-furifosmin Soft tissue sarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The uptake characteristics of technetium-99m hexakis-2-methoxyisobutylisonitrile (MIBI), 99mTc-tetrofosmin and 99mTc-furifosmin in human soft tissue sarcoma cell lines were investigated and compared. After 10–120 min of incubation at 37°C, 32°C and 22°C with 99mTc-MIBI, 99mTc-tetrofosmin and 99mTc-furifosmin, the kinetics of cellular uptake of these tracers in human soft tissue sarcoma cells SW 684 (fibrosarcoma), SW 872 (liposarcoma), SW 982 (synovial sarcoma) and SW 1353 (chondrosarcoma) was assessed. The uptake of 99mTc-MIBI, 99mTc-tetrofosmin and 99mTc-furifosmin was temperature dependent. The kinetics of uptake of 99mTc-MIBI and of 99mTc-tetrofosmin was similar between fibrosarcoma and liposarcoma cells, as well as between synovial sarcoma and chondrosarcoma cells. 99mTc-furifosmin showed similar uptake kinetics in all cell lines. The uptake of 99mTc-furifosmin was, however, significantly higher in liposarcoma than in the other cells. The data indicate that the cellular uptake of 99mTc-MIBI, 99mTc-tetrofosmin and 99mTc-furifosmin is dependent on cellular metabolic activity.
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  • 10
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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