When injected intravenously in rats, emulsion models of triacylglycerol-rich lipoproteins were metabolized like natural lipoproteins and during the hydrolysis of emulsion triacylglycerols, a large fraction of the emulsion phosphatidylcholine was transferred to the plasma high-density lipoproteins. The removal from plasma of emulsion phosphatidylcholine was followed for 2 h in unanaesthetized rats. The half-lives for removal of phospholipid after injection of emulsions stabilized with dioleoylphosphatidylcholine or 1-palmitoyl-2-oleolyphosphatidylcholine were 58-63 min when traced with isologous label. In comparison, the published half-lives of HDL mixed phospholipids in rats are approx. 40 min, indicating that much of the clearance of the emulsion phospholipid could be accounted for by HDL catabolism. Measured LCAT activity was sufficient to account for not more than 2% of the catabolism of the HDL phospholipids labelled by this physiological procedure. Removal from plasma of label was more rapid when the same emulsions were labelled with tracer amounts of the heterologous dipalmitoylphosphatidylcholine, showing that individual phosphatidylcholine species were handled distinctly even when present only in tracer amounts in a bulk of another phosphatidylcholine differing in acyl chains.

Animals↗

PubMed1988

Effects of phospholipid composition on the metabolism of triacylglycerol, cholesteryl ester and phosphatidylcholine from lipid emulsions injected intravenously in rats.

Lipid emulsions were prepared with a similar size and lipid composition to natural lymph chylomicrons, but in which the surface phospholipid was either egg phosphatidylcholine, dioleoyl-, dimyristoyl-, dipalmitoyl- or 1-palmitoyl-2-oleoylphosphatidylcholine (EYPC, DOPC, DMPC, DPPC or POPC). When injected into the bloodstream of conscious rats, the emulsions containing EYPC or POPC were metabolized similarly to natural chylomicrons, consistent with rapid lipoprotein lipase-mediated hydrolysis of triacylglycerols, followed by hepatic uptake of the remnants derived from the emulsions. Phospholipids from the injected emulsions were removed more slowly and became associated with the high-density lipoprotein fractions of the plasma. Emulsions containing DPPC were metabolized differently. Triacylglycerols disappeared very slowly from plasma, indicating lack of hydrolysis by lipoprotein lipase, and phospholipid radioactivity did not transfer to high-density lipoprotein. With emulsions containing DMPC, the plasma removal rates for emulsion triacylglycerols and cholesteryl esters were fast, but phospholipid radioactivity failed to transfer to the high-density lipoprotein fractions of plasma. With DOPC emulsions, clearances were slower than EYPC or POPC emulsions, but transfer to high-density lipoproteins was efficient. Therefore, an unsaturated chain at the glycerol 2-position was necessary for rapid hydrolysis by lipoprotein lipase and for efficient transfer of phospholipids to high-density lipoproteins. With an unsaturated chain at the glycerol 2-position, a saturated chain at the glycerol 1-position optimized the rate of remnant removal from the plasma.

Animals↗

PubMedDate not supplied

Eye injuries among pennant squash players and their attitudes towards protective eyewear.

A questionnaire survey on eye injuries and attitudes towards protective eyewear was conducted among 165 metropolitan pennant squash players; 163 (99%) valid responses were received. The incidence of eye injuries in the survey sample was found to be 17.5 per 100,000 playing hours with a significant proportion (26%) indicating that they had suffered at least one eye injury. Racquets were more common as the source of injury (61%) than squash balls. A large proportion of those injured consulted a doctor (63%) with approximately one-third (or 5% of the total survey sample) having been admitted to hospital for the injury. Only 8% of the sample used appropriate protective eyewear with an additional 2% believing their prescription lenses were a form of protection. The main reason given for using protective eyewear was previous injury to self or others (65% of cases). Doctors and media promotion rated poorly in causing players to use eyewear (6% for each). Most respondents believed eyewear to be of benefit, but fewer than half felt that eyewear should be made compulsory for all players. Only 6% of players said that they would give up the game if use of eyewear was made compulsory.

Attitude to Health↗