Search results for "ISOTOPE"
showing 10 items of 2232 documents
Analysis of the hyperpolarizing effects of forskolin in guinea-pig atrial heart muscle.
1988
The effects of forskolin on action potential configuration and on both uptake and efflux of 86Rb+ were studied in guinea-pig left atria. The action potential was prolonged by forskolin in the plateau range but shortened at the end of repolarization; maximal upstroke velocity and amplitude of slow response potentials were enhanced. In partially depolarized preparations, the resting potential was increased by forskolin; this effect was not prevented by atropine 1 μmol/1. Forskolin augmented the rate constant of 86Rb+ efflux in beating and in resting preparations. The uptake of 86Rbs+ was enhanced by forskolin in resting preparations. It is concluded that forskolin stimulates the Na+, K+ -pump…
Klinisch-experimentelle Studie zur szintigraphischen Darstellung maligner Kopf-Hals-Neoplasien mit57Cobalt-Bleomycin
1975
Tumorscanning of malignomas and their metastatic nodules in head and neck is an enrichment of diagnostic possibilities. For the examination such substances can be used, which are tumoraffine and well to mark with a radio-isotope. Therefore we have marked the cytostatic drug Bleomycine with 57Co. Scans were performed with the Anger-Camera 4 to 6 hrs after intravenous injection of 1 mCi 57Co-Bleomycine. 60 patients with different malignomas have been examined, 46 with tumor-localization in head and neck, the others in thoraxabdomen. 34 (85%) of the head and neck malignomas could be demonstrated; 21 (81%) were squamous cell carcinomas, 13 (69%) sarcomas. The possibilities of this method are sh…
Stimulatory effects of DB-c-AMP and adrenaline on myocardial contraction and 45Ca exchange. Experiments at reduced calcium concentration and low freq…
1973
The effects of adrenaline (2.2×10−6 M) and cyclic N6-2′-O-dibutyryl-adenosine-3′,5′-monophosphate (DB-c-AMP; 10−3 M) on mechanical performance, 45Ca uptake and total tissue calcium concentration were investigated in electrically stimulated left auricles isolated from female rats weighing 180–220 g. The experiments were performed at reduced [Ca]e of 0.45 mM and at various frequencies of stimulation (0–120 beats/min). In the first series of experiments 45Ca incubation time was 5 min. Under these conditions DB-c-AMP as well as adrenaline enhanced contractile force to 300–450% of the control values at all frequencies tested (Fig.1). This increase in contractile force was accompanied by a signif…
Radiomics and radiogenomics in head and neck squamous cell carcinoma: Potential contribution to patient management and challenges
2021
Abstract The application of imaging biomarkers in oncology is still in its infancy, but with the expansion of radiomics and radiogenomics a revolution is expected in this field. This may be of special interest in head and neck cancer, since it can promote precision medicine and personalization of treatment by overcoming several intrinsic obstacles in this pathology. Our goal is to provide the medical oncologist with the basis to approach these disciplines and appreciate their main uses in clinical research and clinical practice in the medium term. Aligned with this objective we analyzed the most relevant studies in the field, also highlighting novel opportunities and current challenges.
Effects of endothelin-1 on the cerebrovascular bed of the goat.
1991
Abstract The aim of the present study was to analyze the effects of endothelin-1 (ET-1) in the cerebrovascular bed of the goat, the importance of endothelial integrity and the contribution of extracellular Ca2+ to these responses. We measured isometric tension and 45Ca2+ uptake in isolated middle cerebral arteries, and cerebral blood flow (CBF) in unanesthetized animals. ET-1 elicited concentration-dependent contractions which were potentiated in arteries without endothelium. Ca2+-free medium and nicardipine inhibited, and Bay K 8644 potentiated the ET-1-induced contractions. ET-1 enhanced 45Ca2+ uptake in isolated arteries. Injections of ET-1 directly into the cerebral circulation decrease…
Pharmacological characterization and autoradiographic localization of histamine H2 receptors in human brain identified with [125I]iodoaminopotentidin…
1992
125I-Aminopotentidine (125I-APT), a reversible probe of high specific radioactivity and high affinity and selectivity for the H2 receptor, was used to characterize and localize this histamine receptor subtype in human brain samples obtained at autopsy. On membranes of human caudate nucleus, specific 125I-APT binding at equilibrium revealed a single component, with a dissociation constant of 0.3 nM and maximal capacity of about 100 fmol/mg of protein. At 0.2 nM, 125I-APT specific binding, as defined with tiotidine, an H2-receptor antagonist chemically unrelated to iodoaminopotentidine, represented 40-50% of the total. Specific 125I-APT binding was inhibited by a series of typical H2-receptor…
Broad-beam transmission data for new brachytherapy sources, Tm-170 and Yb-169
2005
The characteristics of the radionuclides (170)Tm and (169)Yb are highly interesting for their use as high dose-rate brachytherapy sources. The introduction of brachytherapy equipment containing these sources will lead to smaller required thicknesses of the materials used in radiation protection barriers compared with the use of conventional sources such as (192)Ir and (137)Cs. The purpose of this study is to determine the required thicknesses of protection material for the design of the protecting walls. Using the Monte Carlo method, transmission data were derived for broad-beam geometries through lead and concrete barriers, from which the first half value layer and tenth value layer are ob…
Percutaneous Stone Manipulation
1981
Percutaneous stone manipulation by direct ultrasound disintegration, extraction or chemolysis was done on 34 patients. A total of 15 patients presented with an operatively established nephrostomy, while percutaneous nephrostomy and subsequent dilation of the nephrostomy channel were done in 19. The rate of complete stone clearance was 19 of 20 stones after percutaneous nephrostomy and 8 of 16 stones in the group with an operatively established nephrostomy. The primary goal, to remove obstructing pelvic stones, was achieved in all cases. There were no untoward side effects, such as back pressure damage owing to flushing of the collecting system during ultrasound disintegration, or persistent…
Synthesis and in vitro evaluation of (S)-2-([11C]methoxy)-4-[3-methyl-1-(2-piperidine-1-yl-phenyl)-butyl-carbamoyl]-benzoic acid ([11C]methoxy-repagl…
2004
The 11 C-labeled sulfonylurea receptor 1 (SUR1) ligand (S)-2-(( 11 C)methoxy)-4-(3-methyl-1-(2-piperidine-1-yl-phenyl)- butyl-carbamoyl)-benzoic acid (( 11 C)methoxy-repaglinide) was synthesized in an overall radiochemical yield of 35% after 55 min with a radiochemical purity higher than 99%. This compound is considered for the noninvasive investigation of the SUR1 receptor status of pancreatic b-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. The specific activity was 40-70 GBq/lmol. In vitro testing of the nonradioactive methoxy-repaglinide was performed to characterize the affinity for binding to the human SUR1 isoform. Methoxy-repaglinide induce…
Analytical model for the long- distance tracer-transport in plants
2011
International audience; Recent investigations of long-distance transport in plants using non-invasive tracer techniques such as C radiolabeling monitored by positron emission tomography (PET) combined with magnetic resonance imaging (MRI) revealed the need of dedicated methods to allow a quantitative data analysis and comparison of such experiments. A mechanistic compartmental tracer transport model is presented, defined by a linear system of partial differential equations (PDEs). This model simplifies the complexity of axial transport and lateral exchanges in the transport pathways of plants (e.g. the phloem) by simulating transport and reversible exchange within three compartments using j…