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PubMed1979

Multi-element analysis of the rat hippocampus by proton induced X-ray emission spectroscopy (phosphorus, sulphur, chlorine, potassium, calcium, iron, zinc, copper, lead, bromine, and rubidium).

A technique for multi-element analysis of brain tissue by proton induced X-ray emission spectroscopy (PIXE) is described and data from analysis of fixed and unfixed samples from rat hippocampus, neocortex, amygdala, and spinal cord is presented and commented on. The atoms present in the tissue are bombarded with protons which causes the ejection of electrons from the inner shells. When the "holes" are refilled with electrons from outer shells, X-ray quanta characteristic for each element are emitted. Using a high resolution energy dispersive detector a complete X-ray spectrum of the specimen can be recorded in a single measurement. Detection limits less than or approximately 5 p.p.m. of dry matter are obtained for most elements with atomic number greater than 14 (silicon). Around 13 elements were found in concentrations above the detection limits. The grand means for non-fixed hippocampi were e.g. for Zn - 120 p.p.m.; Rb - 20 p.p.m.; Fe - 150 p.p.m.; Pb - 3 p.p.m; Ni - 5 p.p.m.

Amygdala↗
PubMed1992

The effects of rubidium, caesium and quinine on 5-HT-mediated behaviour in rat and mouse--2. Caesium.

Rats and mice were given either CsCl (3 mmol/kg, s.c.) or saline (as control), twice daily for 3 days. The administration of tranylcypromine (TCP) (15 mg/kg, i.p.) to rats pretreated with CsCl produced the 5-HT behavioural syndrome. Pretreatment with CsCl also enhanced the syndrome induced by p-chloroamphetamine (3 mg/kg, i.p.) or by TCP (15 mg/kg, i.p.) plus L-tryptophan (50 mg/kg, i.p.). p-Chlorophenylalanine (300 mg/kg, i.p., daily on 2 consecutive days) or (-)-propranolol (20 mg/kg, i.p.), pindolol (4 mg/kg, i.p.) and ritanserin (0.4 mg/kg, s.c.), all prevented the behavioural syndrome induced by CsCl and TCP in rats. Pretreatment of rats with CsCl potentiated the 5-HT syndrome, elicited by the 5-HT agonists, 8-OH-DPAT (0.5 mg/kg, s.c.), 5-MeODMT (2 mg/kg, s.c.) and quipazine (25 mg/kg, i.p.). Pretreatment with CsCl potentiated the 5-HT2-mediated head-twitches in the mouse but had no effects on hypothermia in the mouse induced by 8-OH-DPAT (0.5 mg/kg, s.c.). The rate of synthesis of 5-HT in the whole brain (excluding cerebellum) was enhanced by pretreatment with CsCl. The enhancement of 5-HT neuronal function by caesium may be related to its ability to block K(+)-channels in neuronal membranes.

Animals↗
PubMed2000

9:45-10:00. Superimposition of EBCT Determined Coronary Calcium Deposits onto Myocardial PET Perfusion Images by Rubidium-82 and Nitrogen-13 Ammonia for Assessment of Flow Limiting Defects.

Calcium localization by Electron Beam CT (EBCT) in the coronary arteries is becoming an important non-invasive method for screening asymptomatic patients for early coronary atherosclerosis. However, the relationship between coronary artery calcium deposits and myocardial perfusion abnormalities has not been established. We have developed software to superimpose location of coronary calcium by EBCT onto PET myocardial perfusion images, so that we can determine the role of location and amount of calcium in the arteries to flow-limiting perfusion defects by PET.EBCT and PET transaxial images are each first converted to three-dimensional arrays of 1 mm voxels. The resulting two image volumes sets are displayed so that a vertical line can be drawn from the clavicle to the spine for proper rotation of the body. The rotated images are then displayed superimposed and are shifted in the vertical, horizontal, and the long axis directions to co-register the EBCT and PET images. The EBCT images are windowed for calcium Houndsfield numbers and calcium location is added to the PET images as a maximum intensity value in the image. The modified PET image volume is then translated back to the PET data format and reprocessed using cardiac analysis software such that the calcium location is superimposed on the PET myocardial perfusion images.Preliminary results of the PET-EBCT superimposition program correlate with location of coronary calcium by EBCT and PET perfusion defects following stress. This technique may be useful for identifying flow-limiting calcium deposits in the coronary arteries.

Journal Article↗
PubMed2000

8:45-90:00. The Influence of a High Fat Meal Compared to an Olestra Meal on Coronary Artery Endothelial Dysfunction by Rubidium (Rb)-82 Positron Emission Tomography (PET) and on Post Prandial Serum Triglycerides.

Background: Cellular changes lead to coronary artery endothelial dysfunction (ED) and precede plaque formation. Clinical events, such as unstable angina and acute coronary syndromes, are common consequences of ED. Coronary artery ED, as characterized by Rb-82 PE, is a perfusion abnormality at rest, which improves following stress. In risk factor modification studies, particularly in cholesterol-lowering trials, coronary artery ED has been demonstrated to be reversible. Other studies have correlated low fat diet modification with improvement in coronary artery disease.Purpose: This study evaluates changes in myocardial perfusion following meals with low versus high TG content, and its influence on post prandial serum TG.Methods: With a randomized, double blind placebo controlled, cross over design, we investigated 19 patients (10 with ED and 9 with normal perfusion) with Rb-82 PET for myocardial blood flow at rest and with adenosine stress. PET images and serum triglycerides were obtained before and after an olestra (OA) meal (2.7g TG, 44g olestra) and a high-fat meal (46.7g TG). Meals were matched for carbohydrate, protein, and cholesterol content.Results: Myocardial perfusion (uCi/cc) increased 11 - 12% following the OA meal compared to the high-fat meal in patients with ED. For all patients combined, serum TG increased significantly (p < 0.01) in the non-OA group with the median change from baseline to 170.0 mg/dl, compared to 21.5 mg/dl in the OA group during the 6 hours following the meal.Conclusions: A single olestra meal significantly diminishes post prandial serum TG levels and improves myocardial perfusion in patients with endothelial disease.

Journal Article↗
PubMed2002

New layered rubidium rare-earth selenides: syntheses, structures, physical properties, and electronic structures for RbLnSe(2).

The compounds RbLnSe(2) (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Ho, Er, Lu) have been synthesized by means of the reactive flux method at 1173 K. These isostructural compounds, which have the alpha-NaFeO(2) structure type, crystallize with three formula units in space group D(3d)(5)-R(-)3m of the trigonal system in cells at T = 153 K of dimensions (a, c in A) La, 4.4313(4), 23.710(3); Ce, 4.3873(3), 23.656(3); Pr, 4.3524(11), 23.655(7); Nd, 4.3231(5), 23.670(4); Sm, 4.2799(4), 23.647(3); Gd, 4.2473(7), 23.689(5); Tb, 4.2197(4), 23.631(3); Ho, 4.1869(6), 23.652(5); Er, 4.1541(8), 23.576(7); Lu, 4.1294(6), 23.614(5). The structure consists of close-packed Se layers in a pseudocubic structure distorted along [111]. The Rb and Ln atoms occupy distorted octahedral sites in alternating layers. The Rb-centered octahedra share edges with the Ln-centered octahedra between layers. Within a given layer, both the Rb-centered and Ln-centered octahedra share edges with themselves. RbTbSe(2) and RbErSe(2) exhibit Curie-Weiss paramagnetism between 5 and 300 K, and RbCeSe(2) exhibits Curie-Weiss paramagnetism between 100 and 300 K. The optical transitions for RbCeSe(2), RbTbSe(2), and RbErSe(2) are in the 2.0-2.2 eV region of the spectrum, both from diffuse reflectance spectra and from first-principles calculations. These calculations also provide insight into the electronic structures and chemical bonding in RbLnSe(2). A quadratic fit for the lanthanide contraction of the Ln-Se distance is superior to the linear one only if the closed-shell atoms La and Lu are included.

Journal Article↗
PubMed2006

Rubidium impurity diffusion in a poly(ethylene oxide)-sodium iodide polymer electrolyte.

Diffusion of the radioisotope (86)Rb in an amorphous polymer-salt complex consisting of poly(ethylene oxide) and sodium iodide was found to be faster at all temperatures investigated than tracer self-diffusion of the smaller alkali metal cation (22)Na. This is the striking result of the first study on impurity diffusion in a polymer electrolyte system and a comparison with ionic self-diffusion and conductivity data previously obtained from the same system. The experimental findings can be rationalized within an ion transport model based on the occurrence of charged single ions and neutral ion pairs. Simultaneous analysis of all data revealed that the diffusivity of Rb(+) is likely to be lower than that of Na(+). Similarly, the diffusivity of RbI(0) pairs was found to be smaller than that of NaI(0) pairs. Surprisingly, the faster overall transport of Rb as measured by radiotracer diffusion appears to be due to a relatively large fraction of RbI pairs, in conjunction with the finding that the ion pair diffusivities exceed the single cation diffusivities by 2 orders of magnitude.

Journal Article↗