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PubMed2005

Does electrocardiographic Q wave burden predict the extent of scarring or hibernating myocardium as quantified by positron emission tomography?

BACKGROUND: The extent of Q wave 'burden' on electrocardiograms (ECGs) has not been correlated with the extent of scarring and hibernation as determined quantitatively by positron emission tomography (PET). OBJECTIVE: A retrospective study was performed to identify if ECG Q wave burden predicts the extent of scarring or mismatch (hibernating myocardium) as defined by rubidium-82/F-18 fluorodeoxyglucose PET viability imaging. PATIENTS AND METHODS: Eighty-three consecutive patients with coronary artery disease undergoing rubidium-82/F-18 fluoro-deoxyglucose viability imaging (mean age 67.9+/-11 years, with a mean ejection fraction of 27+/-7%) formed the study population. Resting ECG was interpreted for the presence or absence of Q waves using standard ECG criteria for Q wave myocardial infarction. Patients were divided into two groups based on their Q wave burden on ECG (small to moderate scar: zero to four Q waves; large scar: five or more Q waves). Automated analysis was used to calculate the extent of scarring and mismatch (hibernating myocardium) on PET as a percentage of left ventricular myocardium. Mean PET scar and mismatch scores were calculated for the two groups. RESULTS: The mean PET scar scores were significantly different between the small to moderate ECG scar group (13.9+/-7.3% of the left ventricle) and the large scar group (20.6+/-8.1% of the left ventricle; P=0.001). The mismatch scores for the small to moderate scar group (4.6+/-2.8%) were not significantly different from those of the large scar group (4.05+/-2.8%; P=0.7). CONCLUSIONS: ECG Q wave 'burden' was associated with the presence of scars as defined by PET but did not accurately predict the amount of hibernating myocardium.

Age Factors↗
PubMed1997

[Collisional energy transfer of the Rb (7 2D) state by ground state K atoms].

In the K-Rb vaper mixtures, the two-photon stepwise excitation of rubidium atoms from the ground state to the state Rb 7 2D is obtained by the use of a rubidium lamp and a cw dye laser. The cross sections for the collisional process Rb (7 2D) +K (4S) -->Rb (5S) +K (7S. 5D) have been measured by observation of the resulting fluorescence. The ratio of K (7S. 5D) to Rb7D fluorescence contains a contribution from K 7S<==>5D mixing. The contribution could effectively be subtracted out using a second experiment in which a potassium lamp and a cw dye laser were used to pump the K7S or 5D state, and the ratio of 7S to 5D or 5D to 7S fluorescence was monitored. The cross sections (in 10(-15)cm2) for Rb7D-->K7S. 5D excitation transfer are 25.8 +/- 10. 3 and 1.5 +/- 0.6 respectively.

English Abstract↗
PubMedDate not supplied

[The linking of the basic functions of the cerebral vessels under the influence of adrenergic substances and general anesthetic agents].

In chronic experiments on conscious and quiet rats norepinephrine, isoproterenol, ether, hexenal and ketamine narcosis decreased the cerebral fraction of cardiac output but increased transcapillary filtration in tissues of rubidium chloride and blood supply in the capacitive part of blood vessels. The changes produced by pyroxan, obsidan and ornid in the same conditions were insignificant. A decrease of the cerebral fraction of cardiac output, an increase of transcapillary filtration of rubidium in the brain tissues and regional blood supply took place under the action of pyroxan, obsidan and ornid in experiments with immobilization of rats.

Anesthetics↗
PubMed1979

[Cesium].

Cesium is an alkaline metal close to Rubidium, which is studied in psychopharmacology in the prospect of a possible antidepressive effect. It has stimulating properties of the motor activity on the animal, antagonizes some sedative substances but does not modify either self-stimulation behaviour or induced agressivity. Given in large doses, Cesium presents hypertensive effects bound with a stimulation of the adrenal Epinephrine secretion. As for the synapses Cesium increases the neuro-transmitter release. However the Norepinephrine turn-over is not modified in the central nervous system while that of Serotonin is increased as well as the cerebral concentrations of Tryptophan, Serotonin and 5.HIAA. These very fragmentary data about the toxico-pharmacological properties of Cesium, as well as the very prolonged half-life of this ion (from 50 to 100 days), explain that contrary to Rubidium it has not still been used in man.

Animals↗
PubMed1985

Effect of gramicidin A and thallium ions on cation effluxes in frog sartorius muscle.

The effluxes of potassium, rubidium, sodium and lithium from the sartorius muscle of Rana temporaria in magnesium-Ringer solution free of sodium and potassium have been studied with the flame-emission technique. The channel-forming antibiotic gramicidin A (2.5 X X10(-7)-1 X 10(-6) mol/l) enhanced the efflux of potassium and rubidium and increased the rate constants of these effluxes. Gramicidin had small if any effect on sodium and lithium effluxes and rate constants. After 60-100 min in a gramicidin-containing medium, the potassium efflux and the corresponding rate constant reached a steady-state level. This steady-state value depended on gramicidin concentration. Effect of gramicidin on both the potassium efflux and the rate constant was partially reversible. Thallium ions (2.5 X 10(-3) and 5 X 10(-3) mol/l) in sodium- and potassium- free magnesium Ringer solution caused a large increase in effluxes of all the cations examined (K+, Rb+ and Na+) both in presence and absence of gramicidin. Possible mechanisms of gramicidin and thallium effects are discussed.

Animals↗
PubMed1989

[Is there a double pathway for the secretion of thyroglobulin: a "short circuit" weakly glycosyl-iodinated and a "long circuit" strongly glycosyl-iodinated?].

Intact rat thyroid lobes incubated in vitro release recently synthesized thyroglobulin (Tg) into the media at a faster rate than they release thyroglobulin stored in follicular structures. Differential release of this Tg fraction cannot be explained by morphological alterations in thyroid architecture during incubation. This rapidly excreted fraction exhibits a low density on rubidium chloride gradients characteristic of poorly sialylated and poorly iodinated thyroglobulin, comigrating on rubidium chloride gradients with thyroglobulin isolated from tunicamycin treated glands. This poorly sialylated and poorly iodinated thyroglobulin is itself unaffected in its density or release into the media by tunicamycin treatment. Tg isolated from the media of tunicamycin treated glands has nearly the same low iodine and low sialic acid content as rat serum thyroglobulin and does not incorporate radiolabelled glucosamine. This fraction thus appear to duplicate properties of low glycosylated-low iodinated thyroglobulin released from thyroid cells in organisms that have no follicular structures and no follicular storage process as well as from thyroid tissue in patients with thyroid disease states, particularly thyroid tumors. Thus it is proposed a "short loop" pathway of low-glycosylated low-iodinated thyroglobulin directly into circulation, that bypasses and is not stored in the follicular lumen, the "long loop".

Animals↗
PubMed1989

Mineral elements in unrefined sugar, and rat reproduction.

Male and female Sprague-Dawley rats were fed purified diets in which the carbohydrate component was either starch or refined sugar (sucrose). The addition to these diets of the ash prepared by the incineration of unrefined muscovado sugar prevented the deficiencies of Factor R seen in the offspring when the diets were not supplemented with ash. Analysis by neutron activation showed that the ash from the unrefined sugar significantly increased the proportion of iron, cobalt, manganese, caesium and rubidium in the diets. The addition of chlorides of all five mineral elements to the diet containing refined sugar also prevented the development of signs of deficiency of Factor R in the pups. However the addition of cobalt chloride alone, or of cobalt and manganese chlorides, did not prevent the deficiency. It is likely that what we have called reproductive Factor R is iron, caesium or rubidium.

Animals↗
PubMed1989

Morphological and functional changes in the rat heart after X irradiation: strain differences.

The hearts of mature male rats of the Wistar and Sprague-Dawley strains were locally irradiated with single doses of 17.5 and 20.0 Gy of X rays, respectively. These two dose levels had previously been shown to result in a comparable latent period between irradiation and the death of rats of these two strains from cardiac failure. Morphological changes in the myocardium and modifications in cardiac function were assessed in the animals at 28, 70, and 100 days after irradiation. The first radiation-induced change which was observed in the myocardium was a rapid decline in capillary density and a loss of alkaline phosphatase activity by the capillary endothelial cells. The capillary density was reduced to approximately 50% of that of unirradiated control values at 28 days and to approximately 40% of the control values between 70 and 100 days after irradiation. The loss of enzyme activity was also detected at 28 days. Examination of histological sections showed an increase by 70 days in the areas with negative enzyme activity up to approximately 70% of the myocardium. The reduction in capillary density and the loss of enzyme activity occurred before any marked pathological changes were seen in the myocardium. The pathological lesions seen in the myocardium at 100 days after irradiation were qualitatively and quantitatively the same in the two strains of rat. Measurements of cardiac output in Sprague-Dawley rats showed a gradual decline in output after irradiation; however, measurements in Wistar rats showed a progressive increase in cardiac output over the same period of time. It was shown by rubidium extraction that there was an increase in the percentage of the total cardiac output distributed to the ventricular muscle of Sprague-Dawley rats, while similar measurements in Wistar rats showed no significant change. In spite of the marked strain differences observed in cardiac output and rubidium extraction, blood perfusion per gram of ventricular muscle was apparently not modified in both strains of rat after irradiation. These findings indicated that the correlation between morphological effects after irradiation and the functional expression of damage is highly complex.

Alkaline Phosphatase↗
PubMedDate not supplied

[The use of potassium-magnesium-sodium chloride-sulfate mineral water and direct current (experimental research)].

To evaluate a therapeutic potential of a test treatment of chronic hepatitis with mineral water followed by hepatic galvanization, the authors have conducted an experimental study on 38 rats. The animals were divided into 4 experimental and 4 control groups. Experimental animals of groups 1 and 2 underwent galvanization of the liver 1 hour after the intake of mineral water in combination with 22Na-labelled sodium chloride, of group 3 in combination with 35S-labelled sodium sulfate, of group 4--with labelled rubidium. Control animals were treated according to the same schedule but galvanization. The study of the hepatic tissue of the sacrificed rats evidenced that oral administration of mineral water followed in an hour by hepatic galvanization results in a significant elevation of hepatic content of labelled sulphur and rubidium, whereas the level of labelled sodium remained unchanged. The data obtained by the authors need to be confirmed in further clinical trials.

Animals↗
PubMed1988

Inward rectification of resting and opiate-activated potassium currents in rat locus coeruleus neurons.

Intracellular recordings were made from rat locus coeruleus neurons in vitro, and membrane currents were measured at potentials from -50 to -130 mV. In the absence of any applied agonists, the slope conductance of the cells increased 3-fold when the cell was hyperpolarized from -60 to -120 mV. This conductance increase was complete within 5 msec of the onset of a hyperpolarizing command and was subsequently independent of time for several seconds. The conductance increase was blocked by cesium chloride (1-2 mM), rubidium chloride (1-2 mM), or barium chloride (1-100 microM). The membrane potential range over which the conductance increased was centered at the potassium equilibrium potential (EK; extracellular potassium concentration, 2.5-10.5 mM): the current/voltage (I/V) relation of the cell could be well described by supposing that there were 2 potassium conductances, one voltage independent (G1) and the other (inward rectifier, Gir) activated according to the expression Gir = Gir,max/(1 + exp[(V - EK)/k]), where k ranged from 15 mV in 2.5 mM potassium to 6 mV in 10.5 mM potassium. The additional membrane potassium conductance that developed when agonists at mu-opioid and alpha 2-adrenoceptors were applied also became larger with membrane hyperpolarization, and this voltage dependence was also reduced or blocked by rubidium, cesium, and barium; in the presence of these agonists the current also reached its final value within 5 msec. However, the conductance increased by the agonists (Gag) was not well expressed by simply increasing the values of G1 and Gir,max. It was best described by a potassium conductance that increased according to Gag,max/(1 + exp[(V - Vm)/k]), where Vm (the potential at which the conductance was half-maximum) was close to the resting potential of the cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Agonists↗
PubMed1978

X-ray microanalysis of cation and hemoglobin contents in red blood cells.

From the results presented, it is clear that X-ray microanalysis can be used to determine the K and Na content in single red blood cells. With a simultaneous determination of Fe content and cation content, it is possible to deduce the sequence of events in the maturation of membrane transport function in relation to hemoglobin synthesis. This kind of deduction can only be made from a cell by cell analysis of the elemental contents. In addition, X-ray microanalysis can be used to measure other elements such as phosphate, which would permit a better understanding of the role of phosphate compound in volume regulation and metabolism of single red cells. Kinetic studies of active transport in single red cells are also possible by measuring the uptake of rubidium which is normally absent in the cell. Rubidium behaves like potassium in its transport characteristics in most red cells. The technique described here can be used to study the normal and the pathological state of single red cells and can also be applied to other single cells such as white cells, bacteria, and dispersed cells in tissue culture.

Animals↗
PubMed1985

Raised sodium pump activity and a circulating sodium transport inhibitor demonstrated on red blood cells of patients with untreated essential hypertension: correlation of pump activity with potassium permeability.

We have studied sodium potassium ATPase activity, the effect of endogenous plasma on sodium pump activity, potassium permeability and intracellular sodium and potassium concentrations in normotensive subjects without (n = 36) and with (n = 33) a positive family history of hypertension, and in patients with untreated essential hypertension (n = 52). Sodium pump activity was studied as ouabain sensitive uptake of rubidium 86 in washed red blood cells, incubated in an artificial medium closely resembling the anorganic constituents of plasma. Any influence of endogenous plasma on sodium pump activity was investigated by re-incubating the washed red blood cells in their own plasma and comparing ouabain sensitive rubidium uptake in the two media. To correct for any possible differences in external potassium concentration, a function for the relation between extracellular potassium concentration and absolute transport rates was derived experimentally. From this, actual transport rates in plasma were corrected by computer to an extracellular potassium concentration of 4.0 mmol/l. Sodium pump activity, concentration of circulating sodium transport inhibitor, potassium permeability and intracellular electrolytes were not statistically different in subjects with and without a positive family history of hypertension. Hypertensives had significantly raised sodium pump activity in artificial medium, but not when red cells were re-incubated in their own plasma. Thus, endogenous plasma inhibited the sodium pump by between 12% and 15%. Hypertensives also had a significantly raised potassium permeability. Potassium permeability and sodium pump activity were correlated significantly. Intracellular sodium concentrations were similar in normotensives and hypertensives, but the later showed a significantly lower intracellular potassium concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

[Changes in the perfusion of the internal organs of rabbits with experimental atherosclerosis treated with a protein hydrolysate].

The authors examined the vascularization of the internal organs of rabbits with experimental atherosclerosis, induced by the method of Sapirstein with 86-Rubidium. The experiments were carried out on male rabbits of the strain Cincilla, fed with cholesterol in a dose of 0.2 gm/kg of body weight daily for a period of 90 days. Part of the animals were treated with protein hydrolysate in a dose of 5 ml/kg of body weight subcutaneously, but the remaining part of the animals-with saline. There was a reduced vascularization in heart, kidney, intestine, liver, adrenals, pancreas, and other internal organs in rabbits fed with cholesterol and treated with saline. Administration of protein hydrolysate had protective effect on the vascularization of the organs accumulation of 86-Rubidium in a large part of the animals presented values higher than rhose of the control group. The authors suggested that under the influence of amino-acids from the protein hydrolysate the state of the endothelial cells was stabilized and the local, feactions of vascularization were stimulated as well.

Animals↗
PubMed1984

Aggregation patterns of bile salts: crystal structure of calcium cholate chloride heptahydrate.

Crystals of calcium cholate chloride heptahydrate, CaC24H39O7Cl . 7H2O, are monoclinic, space group P2(1), with a = 11.918(2), b = 8.636(1), c = 15.302(3) A, beta = 97.93(3) degrees, V = 1559.9(8) A3, and Z = 2. A trial structure was obtained by Patterson and Fourier techniques and was refined by full-matrix least-squares calculations using absorption corrected CuK-alpha diffractometer data. The final R index is 0.047. The crystal structure contains bilayer-type arrangements, with hydrophobic portions of cholate rings sandwiched between layers of polar groups that are interacting with calcium ions and water molecules. The calcium ion is coordinated to five water molecules and to the two carboxylate oxygen atoms of the cholate residue. Two additional water molecules are involved only in crystal packing through the formation of hydrogen bonds. Cholate-cholate hydrophobic interactions involve contacts between the hydrocarbon portions of the carboxylate sidechains and the A and B rings. This results in a staggered packing pattern that is nearly identical to that found in crystals of sodium cholate and rubidium deoxycholate. Similar bilayer aggregation patterns may also be involved in the formation of bile salt micelles in aqueous media. The characteristic bilayer packing arrangement can accommodate a variety of cation-binding patterns, as evidenced by the finding that calcium, sodium, and rubidium ions interact with the polar faces of the bilayers in different ways. The carboxylate sidechain displays two different conformations in the crystal structure of calcium cholate chloride heptahydrate. Variation in sidechain conformation may be of importance in the adjustment required to accommodate different cation coordination schemes.

Bile Acids and Salts↗
PubMed1983

[Increased digitalis-like activity in combined administration of calcium antagonists and digitalis preparations].

It is well recognized that the co-administration of some drugs to persons receiving digoxin results in an increase of serum digoxin levels: it occasionally precipitates digoxin toxicity. There are some possible mechanisms by which different drugs may increase serum glycoside levels: 1) by displacing digoxin from tissue binding sites, 2) by decreasing digoxin renal excretion, 3) by enhancing digoxin absorption, 4) by increasing the inhibition of the ATP-dependent pump. Combined administration of calcium antagonists and B-methyldigoxin is common in patients with heart diseases. Other Authors have found that the co-administration of these drugs with digoxin increases glycoside serum levels, without signs of intoxication. We have examined the effects of this combination on digitalis activity, by Rubidium 86 uptake in erythrocytes. Thirty patients aged 52 to 66 with congestive heart failure were studied. All of these had normal serum creatinine, blood urea and serum protein levels. These subjects received 0,20 mg of B-methyldigoxin daily for nine days; afterwards, ten of them were given in addition 320 mg of verapamil for seven days; the other ten received in addition 60 mg of nifedipine, for seven days; the remaining ten patients received in addition 320 mg of verapamil and 60 mg of nifedipine together, for seven days. Digoxin activity was measured on the eighth, ninth and sixteenth day of treatment by Rubidium 86 uptake in erythrocytes. The technique was that of Bertler. Means were compared with the t test, with the assumption of the equal variances in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Molecular events in close proximity to the membrane associated with the binding of ligands to the Na,K-ATPase.

The membrane-bound fraction of purified Na,K-ATPase was characterized following extensive proteolytic digestion in the presence of various physiological ligands which stabilize different conformational states of the sodium pump. There are distinctive conformational changes of the protein which are revealed by amino-terminal amino acid sequence analysis of the digests following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The changes in cleavage patterns result from alterations in domain-domain interactions of the protein. We provide evidence in the alpha-subunit for (i) tight interaction between part of the cytoplasmic ATP binding domain and the membrane-bound portion of the protein; (ii) involvement of the cytoplasmic loop between M2 and M3 in structural rearrangements upon phosphorylation or ion binding; (iii) generation of the same digested products when either ouabain or potassium (rubidium) is present. Similarly, evidence is provided for conformational sensitivity of the extracellular domain of the beta-subunit. The position of the tryptic cleavage point in the beta-subunit is altered depending on whether the alpha-subunit is phosphorylated or whether rubidium ions are occluded. Based upon the conformationally dependent patterns of exposure and protection of different tryptic cleavage sites in the alpha- and beta-subunits we propose a model for intraprotein interactions within the alpha-subunit and between alpha- and beta-subunits following the binding of physiological ligands to the Na,K-ATPase.

Adenosine Diphosphate↗
PubMed1996

[Oviposition and dispersion of Aedes aegypti in an urban environment].

It is generally accepted that female Aedes aegypti do not fly more than 50-100 m in their entire lifetime, yet the rapidity with which this species colonizes new areas, and the explosive nature of dengue and yellow fever epidemics appear to contradict this. Using molecular methods, we have confirmed that the Ae. aegypti females lay small numbers of eggs at many sites. The distribution of available sites implies that the female may fly a considerable distance to deposit her whole egg batch. We developed a method of monitor dispersal during oviposition by labelling the eggs of the mosquito with rubidium, a relatively rare, non-radioactive element. Eggs laid by females fed in the laboratory on blood containing rubidium were collected in the field with ovitraps and assayed by atomic emission spectroscopy. Our study revealed rapid dispersal over our entire study area, more than 800 m in diameter. We conclude that dispersal may be driven by the availability of oviposition sites. Marked eggs were collected for up to 7 days after feeding, suggesting that the gonotrophic cycle in the field is longer than generally assumed. This implies that calculations of longevity based on ovarian dissection and estimates of the duration of the gonotrophic cycle may need to be revised. Novel studies on sugar feeding and blood feeding are also mentioned.

Aedes↗
PubMed1998

Regulation of the Na+/K(+)-ATPase pump in vitro after long-term exposure to cocaine: role of serotonin.

Long-term exposure to cocaine can cause persistent behavioral changes and alterations in neuronal function. One cocaine-regulated mRNA in the rat brain is the beta-1 subunit of the Na+/K(+)-ATPase pump. We examined both Na+/K(+)-ATPase function and expression after cocaine treatment of pheochromocytoma cells. One-hour exposure to cocaine did not alter Na+/K(+)-ATPase activity, as measured by the ouabain-sensitive component of rubidium uptake. Four days of cocaine resulted in an approximately 30% decrease in Na+/K(+)-ATPase activity. Western blot analyses demonstrated an approximately 25% decrease in levels of the beta-1 isoform, without changes in pump total alpha subunit levels. Treatment with dopamine type 1 or type 2 receptor agonists for the same period did not affect Na+/K(+)-ATPase activity. The serotonin-selective reuptake inhibitor paroxetine caused an approximately 45% decrease in rubidium uptake after 4 days, whereas pump function was not altered after treatment with either the dopamine-selective reuptake blocker nomifensine or the norepinephrine-selective reuptake blocker desipramine. Chronic treatment with both cocaine and LY 278,584, a serotonin type 3 receptor antagonist, did not replicate the cocaine-associated decrease in pump function. Long-term cocaine exposure regulates expression and function of the Na+/K(+)-ATPase pump in neuronal-like cells; this regulation is mediated in part via the serotonin type 3 receptor. Similar Na+/K(+)-ATPase pump regulation in vivo may selectively alter neuronal function in the mammalian brain.

Animals↗