Frank Tallet

Fat embolism in orthopedic surgery: role of bone marrow fatty acid.

Fat marrow was systematically collected from 212 patients (l-year study) admitted for unilateral total knee arthroplasty (PFES incidence = 1.8%). Bone marrow was collected by aspiration in the tibia1 medulary canal. Lipid bone marrow composition of 50 patients were studied by thin-layer chromatography (TLC). Retrospectively, samples from eight patients were selected. Fat bone marrow from four patients meeting the criteria of PFES and four matched controls (patients hospitalized during the same week) were studied for their fatty acid composition by gas-liquid chromatography-mass spectrometry. Four patients ASA physical status I or II (aged 58 -74 years) undergoing unilateral total knee replacement developed a clinical picture that suggested moderate PFES within 24-48 h postoperatively. All four had moderate or severe confusion, hypoxemia when breathing room air, and diffuse pulmonary infiltrates without evidence of left ventricular failure. Two showed petechial rash. We used the semiquantitative PFES index score developed by Schonfeld et al. (4) (Table 1) because there is no consensus about PFES clinical and laboratory signs. This score is arbitrarily considered to be diagnostic of PFES if it is 5 or more.

Characterization of lipoproteins during human cholestasis

We have characterized changes in lipoproteins from cholestatic individuals and reproduced them by incubating lipoproteins from healthy individuals with cholic acid. The cholestatic patients showed an increase in low density lipoprotein (LDL) (>85%), with a smaller proportion of esterified cholesterol, and a fall in high density lipoprotein (HDL) (<10%), with a larger proportion of phospholipids. The protein composition of cholestatic HDL1 was characterized by a smaller proportion of apo A (I, II) and a prominent apo E fraction (39% vs. 9%). These changes involved an increase in degree of molecular packing (order) of HDL1. The addition of cholic acid to serum from healthy individuals altered the lipoprotein distribution, with an increase in LDL, the disappearance of HDL2 and HDL3 and the appearance of HDL1. These HDL1 were characterized by increased phospholipid and reduced apo AI fractions. They also showed a lower density and appeared as spherical particles in contrast to cholestatic HDL. Incubation of healthy HDL with cholic acid in vitro reproduces some of the alteration observed in cholestatic HDL.

Effects of postprandial hyperlipemia on the vitamin E content of lipoproteins

Delayed postprandial clearance of triglyceride-rich lipoproteins (TGRL) could induce a decrease of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) vitamin E content through its transfer into TGRL. We thus studied lipoprotein vitamin E content during postprandial hypertriglyceridemia induced by a high fat meal without vitamin E supplement. Venous blood was drawn from five healthy male volunteers following a 12 h fast at (t0) then 2 h (t2), 4 h (t4), 6 h (t6) and 8 h (t8) after a 80 g fat meal. In plasma, only TG significantly varied during the postprandial period with a large interindividual variability. Mean composition of lipoproteins in terms of mass was not significantly modified. The amount of vitamin E significantly increased in TGRL and decreased in LDL plus HDL at t4 and t6 relative to t0. Vitamin E content of TGRL and LDL but not of HDL decreased significantly at t4. The mean decrease was 20% (range 5%-54%) for the LDL. LDL- and HDL vitamin E content correlated inversely with plasma TGRL levels. Our data suggest that LDL from subjects with delayed chylomicron clearance could be less protected against oxidation.

The immunomodulating agent RU 41740 complexed with very-low-density lipoproteins enhances human polymorphonuclear neutrophil oxidative metabolism in vitro

Added to human serum in vitro, RU 41740, an immunomodulating agent extracted from Klebsiella pneumoniae, binds selectively to lipoproteins containing apolipoprotein B (low-density lipoproteins and very-low-density lipoproteins, VLDL) and, at higher concentrations, to lipoproteins containing apolipoprotein A (high-density lipoproteins). The fact that lipoproteins modulate polymorphonuclear neutrophil (PMN) functions led us to suspect that the VLDL-RU 41740 complex might affect PMN functions. In this study, the effect of this complex on PMN superoxide generation was measured in the presence and absence of the classical stimulants formyl-methionyl-leucyl-phenylalanine and phorbol myristate acetate. The VLDL-RU 41740 complex enhanced the stimulating effect of VLDL on quiescent PMN, but not following stimulation with formyl-methionyl-leucyl-phenylalanine. In contrast, it partially counteracted the inhibiting effect exerted by VLDL alone on phorbol myristate acetate stimulation. Such a complex might be formed in vivo during RU 41740 therapy and constitute an important feature in the immunostimulating properties of the drug.

Free fatty acid microdetermination by gas-liquid chromatography without transmethylating effects of methylation procedure.

A fast and practicable gas-liquid chromatographic method for the quantitation of non-esterified fatty acids (C14:0-C18:2) from 100 microliter plasma is described. This technique includes extraction, purification using the solvents n-heptane and 0.5 M Na2CO3, and methylation by 0.1 M HCl-methanol. Extraction, quantification and optimal methylation conditions without transmethylation have been investigated. Reproducibility is good and results agree with values found in the literature.

Apolipoprotéines et métabolisme plasmatique des lipoprotéines

Resume Les lipoproteines plasmatiques sont des edifices macro-moleculaires caracterises par leur copule lipidique et proteique. Au cours de leur metabolisme, ces lipoproteines echangent en permanence des lipides et des apolipoproteines entre elles ou avec des cellules. Biosynthese et catabolisme des differentes classes de lipoproteines (chylomicrons, VLDL, LDL, HDL) sont presentes successivement sous cet aspect dynamique.