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Biomedical subjects

J D Sallis

Publications and source records attributed to J D Sallis.

At least 37 records · Page 2Linked to original sources
PubMed1986

Atherogenesis. Mitigation of monocyte adhesion to arterial endothelium in hyperlipidemic rats by phosphocitrate, a phosphorylated polycarboxylic acid.

Phosphocitrate, a phosphorylated polycarboxylic acid ameliorates two early events in atherogenesis. When administered to rats on an atherosclerotic diet (112 mumol/kg body wt./day), it reduced monocyte adhesion to aortic endothelium from 34 +/- 7 cells/HPF for untreated rats to 1 +/- 1 cell/HPF, a value seen in normal, non-atherosclerotic rats. Transmission electron microscopy of aortic sections showed no evidence of subendothelial lipid accumulation in phosphocitrate-treated rats despite the high circulating plasma lipid levels. The mechanisms of action of phosphocitrate are unknown but the indications are that its influence may be mediated through its polyanionic chemical nature and/or its ability to modulate cellular calcium accumulation. In addition to its possible therapeutic value as an anti-calcifying and anti-atherogenic compound, phosphocitrate may prove useful as an experimental probe for studying the cellular basis of atherogenesis.

Animals↗
PubMed1985

Phosphocitrate inhibition of 45Ca2+ uptake in rat aortic smooth muscle cells in primary culture.

Phosphocitrate inhibits 45Ca2+ uptake by rat aortic smooth muscle cells in primary culture. Unlike the Ca2+ channel blocking effect of diltiazem, the phosphocitrate effect is neither time dependent nor reliant on a depolarized membrane. Phosphocitrate and diltiazem together in maximum inhibitory concentration show an additive effect. The data suggest that different Ca2+ uptake mechanisms are involved. The potential exists for phosphocitrate to have a therapeutic role in atherogenesis through modulating Ca2+ movements in arterial smooth muscle.

Animals↗
PubMed1984

Effectiveness of phosphocitrate and N-sulpho-2-amino tricarballylate, a new analogue of phosphocitrate, in blocking hydroxyapatite induced crystal growth and calcium accumulation by matrix vesicles.

Phosphocitrate and its analogue N-sulpho-2-amino tricarballylate were compared with ethane-1-hydroxy-1,1-diphosphonate for inhibition of calcium phosphate crystallization in hydroxyapatite induced crystal growth and 45Ca uptake by matrix vesicles. Phosphocitrate (1 microM) was the most potent inhibitor followed by ethane-1-hydroxy-1,1-diphosphonate and N-sulpho-2-amino tricarballylate, the latter requiring a high concentration (100 microM) to be equally effective as an inhibitor.

Animals↗
PubMed1984

Phosphocitrate and its analogue N-sulpho-2-amino tricarballylate inhibit aortic calcification.

This study reports the ability of phosphocitrate and its enzyme-resistant analogue N-sulpho-2-amino tricarballylate to inhibit aortic calcification. Dystrophic calcification of aorta was induced by transplanting fresh aortic segments in Millipore chambers to the peritoneal walls of recipient rats. Daily intraperitoneal injection of the new inhibitors remarkably reduced calcium accumulation by the aortae and prevented the appearance of hydroxyapatite-like crystalline structures. Phosphocitrate was the most effective of the anti-calcifying agents tested, preventing aortic calcification at 1 mumole/day/rat. N-sulpho-2-amino tricarballylate was less effective, reducing aortic calcification by 60% at 10 mumoles/day/rat. The new inhibitors might prove therapeutically useful in man to arrest soft tissue calcification.

Animals↗
PubMed1984

High performance liquid chromatographic profiles of nucleosides, bases and tryptophan in the plasma of the Tasmanian devil and four other marsupial species.

Plasma profiles of nucleosides, bases and trytophan of five marsupial species were established using the reversed-phase mode of high performance liquid chromatography (RHPLC). Within each species, the profiles were highly reproducible and between species there were distinct differences. In the Tasmanian devil, the circulating levels of constituents examined with one exception, were generally lower than in the other marsupials. The exception was a constituent present in large amounts and having the characteristics of a purine nucleoside derivative which was found only in the plasma of the devil.

Animals↗
PubMed1983

The synthesis and characterization of N-sulfo-2-amino tricarballylate: an analog of phosphocitrate and inhibitor of calcification.

The synthesis of N-sulfo-2-amino tricarballylate, a sulfamate analog of phosphocitrate, is described using pyridine-sulfur trioxide to sulfonate 2-amino tricarballylate. The product was purified using selective precipitation and chromatographic techniques and characterized by a variety of physical and chemical means. In particular, its ability to inhibit hydroxyapatite formation and calcium oxalate crystallization was assessed by comparison with known inhibitors including phosphocitrate and pyrophosphate. On the basis of these results, this new compound may ultimately have a role in preventing abnormal biological calcification.

Calcium↗
PubMed1982

Conductivometric determination of urinary oxalate with oxalate decarboxylase.

An enzymatic method for determination of urinary oxalate is described: the acidified urine samples are extracted with chloroform. This manipulation improves the blank values considerably. 1 ml of extracted urine is incubated with oxalate decarboxylase. The CO2 released from the medium is absorbed by Sr(OH)2. The change in conductivity measured in the Sr(OH)2 solution is linearly proportional to the oxalate concentration in urine and the method is specific for oxalate. The mean recovery is 93.2 +/- 2.5%. The coefficient of variation calculated from 28 determinations is 12.6%. The detection limit is 35 nmol. 1 ml of urine is usually sufficient for determination. The mean 24 h urine oxalate excretion of 11 healthy men and 16 women was 240 +/- 20 mumol.

Carboxy-Lyases↗
PubMed1982

Structural factors influencing the ability of compounds to inhibit hydroxyapatite formation.

For a compound to inhibit potently the transformation of amorphous calcium phosphate into hydroxyapatite, it is suggested that the minimum structural requirement is a phosphate group and, at some other position, either another phosphate group preferably or a carboxylic moiety. Primary amino groups abolish inhibitor potential. Inhibitor potency is modified by various secondary factors, including the number and proximity of active groups, their stereochemistry, steric factors, the lability of the molecule, and in special instances its lipophilicity. Parameters used to monitor the transformation indicate that inhibitors can be grouped into two classes, and it is suggested that this is because one class acts as a hydroxyapatite crystal growth inhibitor. The close proximity of two phosphate groups or of a phosphate and multiple carboxylic groups is proposed to determine in part whether or not a compound acts as a crystal growth inhibitor. Further, bulky side groups render a molecule inactive as a crystal growth poison, although it will still inhibit by other mechanisms.

Adenosine Triphosphate↗
PubMed1981

Adenosine triphosphate-deficient erythrocytes of the egg-laying mammal, echidna (tachyglossus aculeatus).

The erythrocytes of the short-beaked echidna (Tachyglossus aculeatus), an egg-laying mammal, were examined for the presence of phosphorylated compounds. The erythrocytes contained only 0.03 +/- 0.01 micromoles of adenosine 5'-triphosphate per milliliter of cells. This amount is two orders of magnitude less than that in human cells. Although the echidna erythrocytes had an abundance of 2,3-diphosphoglycerate and other glycolytic intermediates, no other energy-rich pyridine and purine compounds were detected.

Adenosine Triphosphate↗
PubMed1979

Structure--activity relationship of inhibitors of hydroxyapatite formation.

The relative abilities of some compounds to inhibit the transformation of amorphous calcium phosphate into hydroxyapatite were determined. Organic diphosphates, fructose 1,6-bisphosphate, pyrophosphate, imidodiphosphate and 3-phospholycerate all inhibited to various degrees. Strong inhibition was observed with phosphonoformate, and phosphocitrate proved to be the most powerful of the inhibitors examined. On the basis of these new findings an improved concept of the structure--activity relationship of inhibitors is proposed and mechanisms for inhibitor action are discussed.

Calcium Phosphates↗
PubMed1979

On the possible role of glycosaminoglycans as natural inhibitors of calcium oxalate stones.

An extract of glycosaminoglycans was prepared from normal urine and components fractionated by electrophoresis on Vinylite support medium. Several fractions displayed an ability to inhibit formation of calcium oxalate crystals in vitro. Inasmuch as well recognized urinary glycosaminoglycans such as chondroitin sulfates and hyaluronic acid must contribute to the urine inhibitory power, an unknown material was isolated with potent inhibitory properties. The material contained little detectable uronic acid of hexosamine and had a molecular weight greater than 10,000.

Calcium Oxalate↗