Biomedical subjects

W Haubold

Publications and source records attributed to W Haubold.

3 recordsLinked to original sources

PubMed2000

Synthesis of halogenated polyhedral phosphaboranes. Crystal structure of closo-1,7-P2B10Cl10.

The 12-vertex closo-phosphaborane 1,7-P2B10Cl10 (1) has been prepared in low yield from the pyrolysis reaction of B2Cl4 with PCl3 at temperatures above 400 degrees C. A single-crystal X-ray structure determination of 1 (monoclinic space group P2(1)/n with a = 9.239(2) A, b = 16.786(3) A, c = 15.739(3) a, beta = 93.25(3) degrees, and Z = 4) confirmed that, consistent with its 26 skeletal electron count, the phosphaborane adopts a distorted icosahedral structure with the phosphorus atoms in the 1,7-positions. Crystals of 1 contain toluene in a 1:1 molar ratio embedded between each P atom of neighboring cluster molecules. Alteration of the pyrolytic conditions resulted in the formation of the phosphaboranes P4B8Cl6 (2) and P2B8Cl8 (3), which were characterized spectroscopically. Copyrolysis of B2Cl4 with a mixture of PCl3 and AsCl3 at 450 degrees C generated the six-vertex arsaphosphaborane AsPB4Cl4 (4) and traces of the icosahedral arsaphosphaborane AsPB10Cl10. These compounds are examples of heteroboranes which contain two different group-15 atoms within a single molecule.

Journal Article↗

PubMed1994

Interactions between magnesium and iron. In vitro studies.

In vitro experiments were performed to study the effects of magnesium (Mg) on the absorption of iron (Fe), which have been reported in the literature. Both poorly soluble Mg compounds (Mg oxide and Mg trisilicate) and a readily soluble Mg salt (Mg aspartate hydrochloride trihydrate) were studied along with ferrous gluconate. The influence of the addition of Mg aspartate hydrochloride, Mg oxide and Mg trisilicate on the pH of aqueous acidic solutions was examined initially. As expected, the Mg salts employed as antacids (Mg oxide and Mg trisilicate) were found to have a potent neutralising effect, while after the addition of Mg aspartate hydrochloride the pH value was only slightly shifted toward the alkaline side. These findings suggest that Mg aspartate hydrochloride--unlike Mg oxide and Mg trisilicate--has no appreciable influence on Fe absorption, as the availability of Fe salts in the intestinal tract is pH dependent. A procedure simulating the physiological variations of the pH value in the gastrointestinal tract was used to determine the Fe and Mg content in the supernatant after the addition of the above Fe and Mg salts to aqueous solutions. The addition of poorly water-soluble Mg compounds was shown to result in a drastic reduction in the amount of Fe contained in the supernatant. These data are in agreement with those reported in the literature. However, no decrease in the amount of dissolved Fe was noted in the presence of Mg aspartate hydrochloride. These findings confirm that poorly water-soluble Mg compounds have a high capacity to adsorb Fe and, thus, interfere with Fe absorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspartic Acid↗

PubMed1993

Erythema formation in magnesium-deficient albino rats. A non-invasive model for the screening of anti-inflammatory agents and oral mineral supplements.

The enteral bioavailability of magnesium firmly bound to a fire-proof, inert SiO2-Al2O3 matrix (ground magnesia boats) was studied in magnesium-deficient albino Sprague-Dawley rats, with and without blocking gastric hydrochloric acid secretion with omeprazole. Magnesium was absorbed, although to a small degree, also at anacidity. Pronounced erythema, developing after only some days in hypomagnesemic hypercalcemic rats, are proposed as a non-invasive model for the screening of antiinflammatory substances. Using this model significant protective effects were proven for cromoglycate, polyenthylene glycol 400, and omeprazole; the latter, however, seems more likely to act via a magnesium-sparing mechanism.

Animals↗