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PubMed1984

Splenic fibrosis and sarcomas in F344 rats fed diets containing aniline hydrochloride, p-chloroaniline, azobenzene, o-toluidine hydrochloride, 4,4'-sulfonyldianiline, or D & C red No. 9.

In six carcinogenicity bioassays, male and female F344 rats were fed diets containing aniline hydrochloride (CAS: 142-04-1; hydrochloride benzenamide), p-chloroaniline (CAS: 106-47-8), azobenzene (CAS: 103-33-3), o-toluidine hydrochloride (CAS: 636-21-5), dapsone (CAS: 80-08-0; 4,4'-sulfonyldianiline), or D & C red No. 9 [CAS: D85500000; 5-chloro-2-[2-hydroxy-1-naphthalenyl)azo)-4-methylbenzenesulfon ic acid, barium salt]. The rats, from 6 weeks to 2 years old, were given the compounds at two dose levels, the estimated maximum tolerated dose and one-half that dose. In all six bioassays, dose-dependent incidences of splenic sarcomas and fibrosis were seen, with the highest incidences in male rats. Fibrosis occurred in the splenic parenchyma and/or the capsule. Fatty infiltration also was seen in the spleen. Sarcomas appeared to arise in the splenic red pulp or splenic capsule, usually in association with areas of parenchymal and capsular fibrosis and pigmentation. Larger tumors metastasized to the peritoneal cavity and abdominal organs. In some rats there was marked osseous metaplasia when the primary tumor metastasized to peritoneal surfaces. Other, less common, splenic neoplasms included hemangiosarcoma and hemangiopericytoma. Some rats had such extensive peritoneal involvement that the site of origin of their sarcoma was difficult to determine.

Aniline Compounds↗
PubMedDate not supplied

Intraluminal contrast agents for MR imaging of the abdomen and pelvis.

Magnetic resonance (MR) imaging of the abdomen and pelvis with use of gastrointestinal (GI) contrast agents is slowly emerging as a valuable diagnostic tool. In the past few years, considerable effort has been expended on developing an oral contrast agent to serve as a bowel marker during abdominal and pelvic imaging. Four major categories of agents have been studied: compounds with positive contrast-enhancing characteristics (ie, which increase signal intensity), which may be either miscible or immiscible with bowel contents, and compounds with negative contrast-enhancing characteristics (ie, which decrease signal intensity), which also may be miscible or immiscible. Compared with precontrast images, MR images acquired after administration of GI contrast agents have shown increased anatomic delineation of the bowel lumen, pancreas, and paraaortic nodes, allowing increased detection of pancreatic lesions, improved assessment of bowel wall lesions, and distinction between intrahepatic and extrahepatic lesions. This review focuses on the general physics and requirements for intraluminal GI contrast media for MR imaging, the currently used intraluminal agents and their regulatory status, current and near-future availability, and cost considerations.

Barium Sulfate↗
PubMed1979

Chemotaxis of Bdellovibrio bacteriovorus toward pure compounds.

Positive chemotaxis by Bdellovibrio bacteriovorus strain UKi2 was measured for 139 compounds. Twenty-one compounds were attractants; sensitive attraction was elicited by acetate, propionate, thioacetate, malonate, cis-oxalacetate, D-glucose-6-phosphate, acetyl coenzyme A, ammonium ion, barium ion, manganous ion, and potassium ion. Several of the attractants for B. bacteriovorus strain UKi2 also were attractants to strains 6-5-S and 114; however, strains 109D and 109J were not attracted by the compounds tested. Of 33 compounds tested, 8 were repellents for B. bacteriovorus strain UKi2: n-caproate, alanine, isoleucine, leucine, phenylalanine, tyrosine, cobaltous chloride, and hydronium ion. None of the organic repellents for strain UKi2 elicited repulson from strains 114 or 109D. However, all three strains of Bdellovibrio show aerotaxis. Several compounds were tested for their effects on viability and predacious growth of B. bacteriovorus strain UKi2. No simple correlation was found between attraction or repulsion and benefit or harm to bdellovibrios. The data are consistent with the view that in nature, the greatest survival value of chemotaxis for bdellovibros may be in aerotaxis, attraction to certain inorganic ions and acetate, and repulsion by hydronium ion.

Amino Acids↗
PubMed1975

Studies of nutritional safety of some heavy metals in mice.

Heavy metals have been proposed as nutrient markers to allow the accurate determination of the time of passage, nutrient intake, or apparent utilization of multiple nutrients. In order to evaluate possible toxic effects of scandium, chromium, lanthanum, samarium, europium, dysprosium, terbium, thulium, and ytterbium oxides, and barium sulfate upon growth, general development, reproduction, and lactation, mice were fed different levels of these compounds for three generations. The amount of elements fed were 0,110, 100, and 1000 times the use amount. The use amounts were (in ppm2.) : Sc, 0.12; Cr, 0.02; La.0.40;; Sm. 0.80; Eu, 0.036:TB, 1.20; Dy, 1.20; Tm. 0.08; Tb, 0.12; and Ba, 0.008. The use amount was one-fifth of the concentration required for activation analysis. Mortality and morbidity were negligible. No consistent growth rate changes were observed; however, different groups showed different growth rates during different generations. The number of mice born showed no significant differences amoung treatment groups. Survival, growth rate, hematology, morphological development, maturation, reproduction, and lactational performance were comparable in mice fed the different levels of 10 heavy metal oxides to those mice fed the basal diet.

Animals↗
PubMed1999

Analysis of the environment of beryllium, magnesium and alkaline earth atoms in oxygen-containing compounds.

About 2100 inorganic and organometallic compounds containing beryllium, magnesium and alkaline earth atoms (M) were investigated with Voronoi-Dirichlet polyhedra (VDPs). It is shown that the coordination numbers (CNs) of the M atoms in MO(n) coordination polyhedra can be determined by means of VDPs without crystal-chemical radii. The distributions of the M-O distances in the coordination spheres of the M atoms are bimodal for M = Be or Mg and monomodal for the other alkaline earth metals. Beryllium and magnesium coordination polyhedra containing weak M-O contacts were classified by variants of their distortions. It is found that the volume of the domains of the Mg, Ca, Sr and Ba atoms is independent of their CNs at CN >/= 6 (up to 16 for barium). The possibility of using the model of deformable spheres to describe the crystal structure of the compounds investigated is suggested.

Journal Article↗
PubMed2006

Li80Ba39N9: the first Li/Ba subnitride.

The crystal structure of Li80Ba39N9, a new representative of alkali-alkaline-earth metal subnitrides prepared from the metals and barium azide, was investigated based on single-crystal X-ray diffraction data. The compound has a novel crystal structure with a tetragonal unit cell, space group I(-)42m, a = 16.0763(8) A, c = 32.267(2) A, Z = 2, and V = 8330.0(8) A3. The structure can be described in terms of subnitride clusters with internal ionic bonding and metallic bonding in the rest of the space. The compound contains a new cluster Li12Ba5N6 and polytetrahedral Li clusters based on centered Li13 icosahedra, which are typical for Li-rich intermetallic compounds.

Journal Article↗
PubMed1986

Silicosis in barium miners.

Four men who mined barytes in Scotland and who developed pneumoconiosis are described. Three developed progressive massive fibrosis, from which two died; and one developed a nodular simple pneumoconiosis after leaving the industry. The radiological and pathological features of the men's lungs were those of silicosis and high proportions of quartz were found in two of them post mortem. The quartz was inhaled from rocks associated with the barytes in the mines. The features of silicosis in barium miners are contrasted with the benign pneumoconiosis, baritosis, that occurs in workers exposed to crushed and ground insoluble barium salts. Diagnostic difficulties arise when silicosis develops in workers mining minerals known to cause a separate and benign pneumoconiosis. These difficulties are compounded when, as not infrequently happens, the silicotic lesions develop or progress after exposure to quartz has ceased.

Aged↗
PubMed1990

Evaluation of diagnostic radiopaque contrast materials used with calcium hydroxide.

An evaluation of three different radiopaque materials used in combination with calcium hydroxide powder for diagnostic contrast was made. Diatrizoate meglumine (65%) and iothalamate meglumine (60%) compared favorably with barium sulfate (35%). Since barium sulfate has demonstrated problems by altering the manipulative properties of calcium hydroxide as well as demonstrating a residual radiopacity, there may be advantages to the use of resorbable diatrizoate or iothalamate compounds as alternatives. These soluble iodine compounds also make possible an excellent aqueous medium in which to mix calcium hydroxide.

Barium Sulfate↗
PubMed1991

The effect of strophanthidin on action potential, calcium current and contraction in isolated guinea-pig ventricular myocytes.

1. A method is described for producing high yields of calcium-tolerant ventricular myocytes from guinea-pig hearts (73.4% rod-shaped cells, n = 19). Their action potential (AP) and membrane currents were recorded using conventional microelectrodes and cell shortening was measured optically using a linear photodiode array. 2. The sensitivity of the guinea-pig Na(+)-K+ pump to strophanthidin (a rapidly acting digitalis analogue) was determined by measuring the inhibition of outward pump current by different doses. The pump was found to have a dissociation constant (KD) for strophanthidin of 1.11 x 10(-5) M, and 5 x 10(-4) M-strophanthidin inhibited the pump maximally. 3. Exposure to strophanthidin resulted in an initial lengthening followed by a shortening of the AP, and an increased contraction. Initial AP lengthening was associated with a more positive AP plateau which became more negative as the AP shortened. 4. There was a reversible reduction of Ca2+ current (ICa) during exposure to strophanthidin. ICa changed reciprocally with contraction and with a similar time course. 5. Strophanthidin exposure caused a reduction of ICa at all activating voltages, suggesting that it resulted in a reduction of Ca2+ conductance with little change of its voltage dependence. 6. The role of an increase of intracellular calcium (Cai2+) was investigated by impaling myocytes with microelectrodes containing BAPTA 1,2-bis (2-amino-phenoxy)ethane-N,N,N',N'-tetraacetic acid, a calcium chelator) to increase Cai2+ buffering. Strophanthidin still shortened the AP when BAPTA was present, suggesting that a rise of Cai2+ is not a major cause of AP shortening. 7. Although AP shortening was little affected, the decline of ICa with strophanthidin was markedly reduced when BAPTA was present, suggesting that a rise of Cai2+ was the cause of the ICa decline with strophanthidin. 8. When barium ions carried the current through Ca2+ channels, strophanthidin did not reduce Ca2+ channel current, suggesting that this compound does not have a direct inhibitory effect on the channel. 9. The results suggest that strophanthidin causes a reduction of ICa by increasing Cai2+, via the mechanism of Cai(2+)-dependent inactivation of ICa. The reduction of ICa at least partially explains the AP shortening and more negative plateau with strophanthidin. 10. The shortening of the AP, more negative plateau and reduced ICa have negative inotropic effects which oppose the direct positive inotropic effect of strophanthidin.

Action Potentials↗
PubMed1990

A maxi calcium-activated potassium channel from chick lens epithelium.

The apical membrane of embryonic chick lens epithelium contains at high density, a large conductance K+ channel whose open probability is increased by Ca++ at the inner surface of the membrane and by depolarization. The conductance of the channel when it is fully open in symmetrical 150 mM K+ solutions is 214 +/- 3 pS (mean +/- std. error). The current through the channel is a function of the K+ concentration. Gating (open probability) at positive transmembrane voltages increases as the internal [Ca++] is raised above 10(-7) M. The open probability decreases monotonically as the transmembrane voltage is made more negative. The channel is at least 87 times more permeable to K+ than to Na+ or Li+ and shows appreciable permeability to Rb+ and NH4+. It has at least three subconductance levels amounting to approximately 3/4, 1/2, and 1/4 the fully open unitary conductance. The occurrence of these subconductance levels is highly variable from one patch to another. The channel is blocked by physiological levels of internal Na+ but not over a physiological voltage range. This block is partially overcome by elevated external K+. This K+ channel from chick lens epithelium is blocked by a number of compounds known to block BK channels in other tissues. Here we show that decamethonium and Ba++ are effective blockers when added to the inner bathing solution at concentrations greater than .1 mM. Tetraethylammonium, Cs+, quinine, quinidine and Ba++ are all effective blockers when applied to the outer side of the channel in the .1 mM - 5 mM range. With the exception of internal Ba++, all of these compounds produce a fast flicker-type blockade. We use a one-site model to quantify the blockade caused by these flicker producing agents. The voltage dependence of the blockade by Cs+ suggests that this channel probably allows multiple occupancy.

Animals↗
PubMed2000

Barium thiolates and selenolates: syntheses and structural principles.

The synthesis and structural characterization of a family of barium thiolates and selenolates is described. The thiolates were synthesized by metallation of thiols, the selenolates by reductive insertion of the metal into the selenium-selenium bond of diorganodiselenides. Both reaction sequences were carried out by using barium metal dissolved in ammonia; this afforded barium thiolates and selenolates in good yield and purity. The structural principles displayed in the target compounds span a wide range of solid-state formulations, including monomeric and dimeric species, and separated ion triples, namely [Ba(thf)4(SMes*)2] (1; Mes* = 2,4,6-tBU3C6H2), [Ba(thf)4(SeMes*)2] (2), [Ba([18]crown-6)(hmpa)2][(SeMes*)2] (3), the dimeric [(Ba(py)3(thf)(SeTrip)2)2] (4; py = pyridine, Trip = 2,4.6-iPr3C6H2), and [Ba([18]crown-6)(SeTrip)2] (5). The full range of association modes is completed by [Ba([18]crown-6)(hmpa)SMes*][SMes*] (6) communicated earlier by this group. In the solid state, this compound displays an intermediate ion coordination mode: one anion is bound to the metal, while the second one is unassociated. Together these compounds provide structural information about all three different association modes for alkaline earth metal derivatives. This collection of structural data allows important conclusions about the influence of solvation and ligation on structural trends.

Journal Article↗