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PubMed1978

Interaction between barium, strontium and calcium in histamine release by compound 48/80.

Pre-incubating rat peritoneal and pleural mast cells for 30 min at 2 degrees C in Ca2+-free Tyrode containing Ba2+ (30 mM) markedly reduced histamine release by compound 48/80 (0.5 microgram/ml). Evoked secretion was not significantly altered by pre-incubation with Sr2+ (30 mM) at this temperature whilst Mg2+ (30 mM) and La3+ (0.1 mM) slightly inhibited and potentiated release respectively. The effect of Ba2+ was concentration related and progressively reversed by Ca2+ (1--10 mM). Pre-incubation at 37 degrees C in Ca2+-free medium alone substantially reduced histamine release by compound 48/80. This reduction was unaltered by either Mg2+ (30 mM) or La3+ (0.1 mM), prevented by either Sr2+ (30 mM) or Ca2+ (1 mM) and augmented by Ba2+ (30 mM) which also markedly increased spontaneous histamine release during pre-incubation at 37 degrees C. Results suggest that Ba2+ and Sr2+ interact with cell-fixed calcium to modulate histamine release by compound 48/80.

Animals↗
PubMed1978

Phosphorus-31 chemical-shift tensors in barium diethyl phosphate and urea-phosphoric acid: model compounds for phospholipid head-group studies.

The molecular orientations of the 31P chemical-shift tensors in the phosphodiester barium diethyl phosphate (BDEP) and in the nonesterified urea-H3PO4 (UPA) complex were determined from single-crystal studies. Although the tensors possess qualitatively similar orientations, there are differences between the two tensors of the order of 20 degrees. The principal values of the BDEP tensor are within 5% of those found in powder spectra of phospholipids, and, for this and other reasons, which are discussed in detail, we believe BDEP is a good model chemical-shift tensor for lipid phosphate. With the BDEP tensor alone, one can label certain head-group conformations as improbable, and, in conjunction with oriented bilayer spectra, one can determine the conformation of lipid head groups. In addition, we suggest a technique for orienting crystals based on the transformation properties of shift tensors, and we demonstrate this method by applying it to UPA. Finally, our results allow us to assess the effect of shift anisotropy relaxation on 31P liquid spectra at high fields.

Magnetic Resonance Spectroscopy↗
PubMed1990

Toxicology of selected pesticides, drugs, and chemicals. Anticoagulant, cholecalciferol, and bromethalin-based rodenticides.

The control of rodent pests is a continuing goal of mankind. To this end, a multitude of rodenticides have been produced, each designed to kill rodents by exerting their toxic effects on various body systems. As examples, veterinarians have had to manage companion animal poisonings due to anticoagulant, sodium fluoroacetate (compound 1080), thallium, barium carbonate, and zinc phosphide-based rodenticides. Many of these rodenticides were introduced because of their anticipated safety in relation to nontarget species; unfortunately, this has not been the case. Veterinarians must attempt to identify the specific rodenticide involved in poisoning cases. Therapeutic success in these poisonings is often more dependent upon symptomatic and supportive care rather than the use of antidotal therapy.

Aniline Compounds↗
PubMed1997

Pediatric musculoskeletal computed radiography.

BACKGROUND: In conventional radiography, a film-screen system serves as the X-ray detector and the film also functions as an archival and display medium. Unlike film-screen radiography, these functions are uncoupled in computed radiography (CR). CR uses conventional radiographic equipment to expose an image on a storage phosphor plate instead of a film-screen combination. OBJECTIVE: To review the basic concepts of CR and to provide a background for discussion of specific musculoskeletal applications of CR in children. MATERIALS AND METHODS: Various aspects of musculoskeletal CR in children are presented based on our 4 years' experience and a review of the literature. RESULTS: A greater amount of scatter capture occurs with storage phosphor CR than with a film-screen system in the 70- to 120-kVp range. This is attributed to a lower K-absorption edge of barium in the barium fluorohalide (BaFBr) compound used in the imaging plate. A significant reduction of scatter to primary radiation, improvement in bony trabecular sharpness, and improvement in line pair resolution can be achieved in pediatric musculoskeletal imaging using an air gap without an increase in the skin entrance dose as compared to the non-grid table top technique. With CR, in addition to proper radiographic exposure technique, one needs to preprogram and select the optimal processing technique for each anatomic region, projection and age group of the child. CONCLUSION: The main advantages of CR in pediatric musculoskeletal imaging consist of a reduction in radiation dose for many applications, improved contrast resolution, near elimination of repeat radiographs related to exposure errors, and digital processing capabilities for image enhancement, storage, retrieval, display and transmission. The current limitations of CR include the moderately high start-up cost, the long learning curve to produce optimal films, and the reduced spatial resolution.

Artifacts↗
PubMed1977

Enkephalins inhibit intestinal motility: mode of action.

In the guinea pig isolated terminal ileum the opioid pentapeptides, methionine-enkephalin and leucine-enkephalin, dose-dependently inhibit contractile responses induced by electrical field stimulation releasing endogenous acetylcholine, and by specific noncholinergic compounds including histamine, barium chloride, and beta-acetyl-digoxin. Tissue levels of cAMP and cGMP remain unchanged. We conclude that enkephalins exert their effects by a direct action at or within the muscle cell and may play a physiological role in the local control of the gut smooth muscle motility.

Animals↗
PubMed2005

Synthesis of homoleptic barium alkoxides and aryloxides and their reactions with Al(CH(3))(3): a convenient route to heterometallic species.

Reactions of metallic Ba with benzofuranol (dbbfoH) or diethylene glycol give homoleptic and homonuclear complexes Ba(dbbfo)(2)(dbbfoH)(2).3dbbfoH and Ba{O(CH(2)CH(2)O)(2)}{O(CH(2)CH(2)OH)(2)}(2) (60-89%). Both compounds and formerly described Ba{O(CH(2)CH(2)O)(2)Me}(2) react with Al(CH(3))(3) to yield trinuclear heterobimetallic low-coordinated barium compounds with structure and geometry depending on the reaction stoichiometry and crystallization procedure.

Aluminum↗
PubMed2000

Determination of titanium NMR parameters of ATiO3 compounds: correlations with structural distortion.

Solid state 47,49Ti NMR spectra have been obtained for a number of perovskite and ilmenite ATiO3 compounds. The 49Ti quadrupole coupling constant varies from 2.75 MHz (CaTiO3) to 15.5 MHz (MgTiO3) and the electric field gradient at the titanium site was found to correlate well with the shear strain, independent of structure. The chemical shift in the perovskite structures varies by approximately 160 ppm and correlates well with the mean Ti-O distance. The 25Mg and 113Cd NMR parameters are also reported for the relevant compounds.

Barium↗
PubMed1990

The action of caffeine on inward barium current through voltage-dependent calcium channels in single rabbit ear artery cells.

The effect of caffeine on inward current carried by barium ions through voltage-dependent calcium channels has been investigated in single rabbit ear artery cells using whole-cell voltage-clamp techniques. Caffeine (1-30 mM) caused a rapid and reversible concentration-dependent blockade of barium current and a related compound, 3-isobutyl-1-methylxanthine (IBMX), was a more potent inhibitor of barium current. Caffeine-induced inhibition of barium current showed no voltage- or use-dependence and caffeine did not alter the steady-state inactivation of barium current. The effect of caffeine was not blocked by extracellular or by intracellular ryanodine or inclusion of both 5 mM 1,2-bis(2-aminophenoxy)-ethane N,N,N',N',-tetraacetic acid (BAPTA) and 2 mM ethylene glycol-bis(beta-amino ethyl ether) N,N,N',N',-tetraacetic acid (EGTA) in the intracellular solution. Rolipram and M&B 22984, non-xanthine inhibitors of phosphodiesterase, did not diminish inward barium current. The data indicate that caffeine and IBMX block voltage-operated calcium channels and it is suggested that this is due to a direct interaction of methylxanthines with the calcium channel.

1-Methyl-3-isobutylxanthine↗
PubMed2003

Barium chromate is cytotoxic and genotoxic to human lung cells.

Hexavalent chromium (Cr(VI)) compounds are widely accepted as human lung carcinogens. However, there have been few investigations of the genotoxicity of Cr(VI) in human lung cells. Moreover, our knowledge of the effects of Cr(VI) in human lung cells is further limited because the available data generally focus on the effects of only lead chromate (PbCrO(4)) and sodium chromate (Na(2)CrO(4)). To fully understand these carcinogenic compounds, the genotoxic effects to its target cells need to be evaluated for additional Cr(VI) salts. Accordingly, we investigated the cytotoxicity and clastogenicity of barium chromate (BC) in a human lung cell culture model (WTHBF-6 cells). We found that BC induced concentration-dependent cytotoxicity in WTHBF-6 cells, with relative survival of 88%, 74%, 67%, 12%, 3%, and 0.1% after exposure to 0.01, 0.05, 0.1, 0.5, 1, and 5 microg/cm(2) BC, respectively. Similarly, the amount of chromosomal damage also increased with concentration after a 24-h exposure. Specifically, 0.01, 0.05, 0.1, and 0.5 microg/cm(2) BaCrO(4) damaged 5%, 9%, 22%, and 49% of metaphase cells, with the total damage reaching 5, 10, 28, and 65 aberrations per 100 metaphases, respectively. Concentrations of 1 and 5 microg/cm(2) BC induced a profound cell cycle delay, and no metaphases were observed. The spectrum of damage included chromatid and chromosome-type lesions consistent with mechanistic events associated with the activation of oncogenes and inactivation of tumor suppressor genes. Overall the data indicate that BC is cytotoxic and genotoxic to human lung cells.

Barium↗
PubMedDate not supplied

The potential site of disordered gallbladder contractility during the early stage of cholesterol gallstone formation.

BACKGROUND/AIMS: Feeding a high cholesterol diet to dogs causes a reduction in gallbladder smooth muscle contractility with a consequent stasis. Gallbladder stasis is an important link between the hepatic secretion of cholesterol saturated bile and the formation of cholesterol gallstones. METHODOLOGY: In this study we tried to localize the probable site of gallbladder smooth muscle dysfunction in a well established animal model of cholesterol gallstone disease. Adult male dogs were fed either a high or low cholesterol diet (control group). Strips of gallbladder smooth muscle for tension development were stimulated with two groups of agonists and dose response curves were plotted for all agonists used. RESULTS: The forces developed in response to the first group of agonists, the cell membrane-active agonists, e.g. acetylcholine, cholecystokinin, and potassium chloride were decreased in high cholesterol fed dogs with an increased cholesterol saturation of bile when compared to the control group. On the other hand, the contractile response showed non-significant differences between the test and the control group on using the second group of agonists that bypass the intact sarcolemmal membrane and stimulate directly either the contractile mechanism, e.g. barium, or the intracellular signal transduction pathways e.g. aluminum fluoride. CONCLUSION: We conclude that the smooth muscle defect responsible for disordered gallbladder contractility in high cholesterol fed dogs most probably involves the sarcolemmal membrane.

Acetylcholine↗
PubMed1982

Reappraisal of contrast media used to detect upper gastrointestinal perforations: comparison of ionic water-soluble media with barium sulfate.

Iodinated water-soluble compounds have been widely recommended as the most suitable contrast media for diagnosis of gastrointestinal perforations. However, the authors present 6 cases in which mucosal tears and transmural perforations of the upper gastrointestinal tract were either unrecognizable or inadequately shown during initial evaluation with methylglucamine diatrizoate. Re-examination with barium sulfate demonstrated the precise location and extent of the perforations. Reasons for the higher diagnostic yield of barium studies are explained on the basis of experimental and clinical observations.

Adult↗
PubMed1995

Dotarizine versus flunarizine as calcium antagonists in chromaffin cells.

1. Dotarizine is a novel piperazine derivative structurally related to flunarizine that is currently being evaluated in clinical trials for its antimigraine and antivertigo effects. This clinical profile may be related to its Ca2+ antagonist properties. Therefore, the actions of both compounds as calcium antagonists were compared in bovine chromaffin cells. 2. Dotarizine and flunarizine blocked 45Ca2+ uptake into K+ depolarized chromaffin cells (70 mM K+/0.5 mM Ca2+ for 60 s) in a concentration-dependent manner, with IC50s of 4.8 and 6.7 microM, respectively. 3. Dotarizine and flunarizine also inhibited the whole-cell Ca2+ and Ba2+ currents (ICa, IBa) in voltage-clamped chromaffin cells, induced by depolarizing test pulses to 0 mV, during 50 ms, from a holding potential of -80 mV. Blockade exhibited IC50s of 4 microM for dotarizine and 2.2 microM for flunarizine. Dotarizine increased the rate of inactivation of ICa and IBa; inhibition of whole-cell currents was use-dependent. 4. Transient increases of the cytosolic Ca2+ concentration, [Ca2+]i, produced by K+ stimulation (70 mM K+ for 5 s) of single fura-2-loaded chromaffin cells, were also inhibited by dotarizine and flunarizine with IC50s of 1.2 and 0.6 microM, respectively. Upon washout of dotarizine, the [Ca2+]i increases recovered fully after 5-10 min. In contrast, the responses remained largely inhibited 10 min after washing out flunarizine. 5. Catecholamine release induced by K+ stimulation (10-s pulses of 70 mM) was inhibited by dotarizine with an IC50 of 2.6 microM and by flunarizine with an IC50 of 1.2 microM. The blocking effects of both compounds developed slowly, and was fully established after 20-30 min of superfusion. While blockade by dotarizine quickly reversed upon its washout, that of flunarizine lasted even 25 min after washing out.6. Catecholamine release from electroporated chromaffin cells triggered by 10 micro M Ca2+ was not affected by 10 micro M dotarizine or flunarizine.7. Overall, the results suggest that dotarizine behaves as a Ca2+ antagonist in bovine chromaffin cells. It exhibits a potency similar to flunarizine in blocking Ca2+ entry, Ca2+ channels, Cai2+ signals and secretion. The dotarizine effects are readily reversible suggesting that in contrast to flunarizine, it does not accumulate in cells. Dotarizine is devoid of intracellular effects on the secretory machinery. All its blocking effects on Ca2+ entry, [Ca2+]i rise and secretion are probably due to blockade of various Ca2+channel subtypes in chromaffin cells. This blockade is use-dependent and seems to be due to the increase by dotarizine of the rate of Ca2+ channel inactivation.

Animals↗