Pro- and antioxidant activities of docosahexaenoic acid on human blood platelets.

n - 3 polyunsaturated fatty acids may protect against vascular diseases, however, their high accumulation in membranes may increase lipid peroxidation and subsequently induce deleterious effects in patients suffering from oxidative stress. This led us to investigate in vitro the dose-dependent effect of docosahexaenoic acid (DHA) on the redox status of human platelets. We have compared the effect of different DHA concentrations (0.5, 5 and 50 micro mol L(-1)) corresponding to DHA/albumin ratios of 0.01, 0.1 and 1. At the highest concentration, DHA elicited a marked oxidative stress, as evidenced by high malondialdehyde and low vitamin E levels whereas the lowest DHA concentration significantly decreased the malondialdehyde formation, with no change in vitamin E. The proportion of DHA was only increased in plasmalogen phosphatidylethanolamine at low concentration to rise in all phosphatidyl-choline and -ethanolamine subclasses at high concentration. Thus, the results show a biphasic effect of DHA with antioxidant and prooxidant effects at low and high concentrations, respectively, with a possible relationship with the phospholipid subclass in which it accumulates.

Corticosteroid-resistant pyoderma gangrenosum associated with Crohn's disease: rapid cure with infliximab.

A 41-year-old woman with Crohn's disease had a severe and rapidly extensive corticosteroid-resistant pyoderma gangrenosum (PG) of the leg. She had been treated 2 years previously with antibiotics and surgery for a similar lesion of the back of the hand which had been diagnosed as a fulminating infection. Infliximab 5 mg/kg was given at weeks 0, 5 and 9. A dramatic response was observed within 72 h with a favourable effect persisting for 4 weeks after each infliximab infusion. A complete healing was achieved at week 11. This case illustrates that (1). PG of the hand is frequently misdiagnosed as an infection and treated with inappropriate therapies; (2). infliximab may be an interesting alternative in corticosteroid-resistant PG associated with Crohn's disease.

Characterization of plasma unsaturated lysophosphatidylcholines in human and rat.

Unsaturated lysophosphatidylcholines (lysoPtdCho) bound to albumin circulate in blood plasma and seem to be a novel transport system for carrying polyunsaturated fatty acids (PUFA) to tissues that are rich in these fatty acids, such as the brain. The potential of these lysoPtdCho as a significant source of PUFA for cells has been assessed by comparing their plasma concentration with that of unsaturated non-esterified fatty acids (NEFA) bound to albumin. In humans, the PUFA concentration was 25.9+/-3.1 nmol/ml for these lysoPtdCho, compared with 33.4+/-9.6 nmol/ml for NEFA; in rats the equivalent values are 14.2+/-0.6 and 13.1+/-1.1 nmol/ml respectively (means+/-S.E.M.). The lysoPtdCho arachidonic acid content was 2-fold (human) and 5-fold (rat) higher than that of NEFA. In human and rat plasma, unsaturated lysoPtdCho were associated mainly with albumin rather than lipoproteins. The rate and extent of the acyl group shift from the sn-2 to sn-1 position of these lysoPtdCho were studied by the incubation of 1-lyso, 2-[(14)C]C(18:2)n-6-glycerophosphocholine (GPC) with plasma. The rapid isomerization of this lipid occurred at pH 7 (20% isomerization within 2 min) and was not prevented by its association with albumin. The position of the acyl group in the lysoPtdCho circulating in plasma was studied by collecting blood directly in organic solvents containing 1-lyso,2-[(14)C]C(18:2)n-6-GPC as a marker of isomerization that occurred during sampling and analysis. Approx. 50% of the PUFA was located at the sn-2 position, demonstrating that substantial concentrations of 2-acyl-lysoPtdCho are present in plasma and are available for tissue uptake, where they can be reacylated at the sn-1 position to form membrane phospholipids.

Synthesis of acetyl,docosahexaenoyl-glycerophosphocholine and its characterization using nuclear magnetic resonance.

Docosahexaenoic acid (DHA) circulates in mammals in lipoproteins and bound to serum albumin as a nonesterified fatty acid as well as esterified in lysophosphatidylcholine (lysoPC). 1-Lyso,2-DHA-glycerophosphocholine (GPC) is an unstable isomer because of a primary alcohol at the sn-1 position. To keep DHA at the sn-2 position of lysoPC, its usual position for the corresponding lysoPC to be acylated into PC in tissues, we synthesized 1-acetyl,2-DHA-GPC and confirmed its structure by use of nuclear magnetic resonance (NMR) spectroscopy in comparison with its positional isomer, 1-DHA,2-acetyl-GPC. 1-Lyso,2-DHA-GPC was prepared from 1-stearoyl,2-DHA-GPC by enzymatic hydrolysis and purified by high-performance liquid chromatography. The isomerization of 1-lyso,2-DHA-GPC into 1-DHA,2-lyso-GPC was obtained by keeping the former overnight at room temperature under nitrogen. Both lysoPC isomers were acetylated by acetic anhydride into 1-acetyl,2-DHA-GPC and 1-DHA,2-acetyl-GPC, respectively, and the resulting phospholipids were fully characterized by NMR. In particular, the 1,2 substitution pattern of the acetyl and DHA chains could be easily detected by 2D heteronuclear multibond correlation. We conclude that 1-acetyl,2-DHA-GPC might be considered as a stable form of 1-lyso,2-DHA-GPC for its delivery to tissues, if the latter exhibits acetyl hydrolase activity.

[Surgical treatment of myeloma localized in the spine]. / Le traitement chirurgical des localisations rachidiennes du myélome.

PURPOSE OF THE STUDY: Myeloma represents as much as 40 per cent of malignant primary spine tumors. The aim of this study was to discuss the indications for surgical treatment of spinal myeloma. MATERIAL AND METHODS: 18 patients presenting spinal localization of myeloma were operated on. There were 10 males and 8 females. Mean age was 59.9 (41-86). Pain was present in all patients. Seven patients presented neurologic signs: Frankel B: 1 case, Frankel C: 3 cases, Frankel D: 3 cases. Surgical treatment included anterior approach in 6 cases, posterior approach in 5 cases and combined approach in 7 cases. Postoperative medical treatment (chemotherapy, radiotherapy, immunotherapy) was performed in all cases. RESULTS: Diagnosis was made after surgery in 10 patients on histological findings. There were 13 myelomas and 5 plasmacytomas. Decrease of pain was observed in all cases at first postoperative month; 9 patients were pain free at the 6th postoperative month. Complications occurred in 4 cases: 2 local infections after radiotherapy; mobilisation of an anterior implant in one case and local recurrence in one case requiring secondary surgery. Nine patients were alive at review with a mean follow-up of 57 months. Nine patients were dead with a mean follow-up of 15.4 months. Preoperative Karnofsky score was 50 per cent; Karnofsky score was 77 per cent at follow-up. Neurologic deficit improved in 5 out of 7 cases. DISCUSSION: Primary treatment of myeloma is medical associating chemotherapy, corticotherapy, radiotherapy and immunotherapy. Plasmocytoma is frequently revealed by neurologic deficit. Staging of myeloma gives the prognostic. Surgical treatment must be performed when pain is not controlled by medical treatment or when neurologic deficit is present. CONCLUSION: Surgery allows rapid and durable functional recovery in patients with spinal myeloma; surgery should be associated to additional medical treatment, unlike spinal metastasis.

[Surgery for degenerative lumbar disc disease. Should the black disc be grafted?]. / La chirurgie des discopathies lombaires. Faut-il greffer le disque noir?

PURPOSE OF THE STUDY: To determine predictive factors allowing to improve the results of fusion in low back pain treatment. MATERIAL AND METHOD: Fifty six patients were retrospectively reviewed. Average age at surgery was 42. In 29 cases, discectomy or nucleolysis had been previously performed. All patients were treated by anterior lumbar interbody fusion. Functional results were assessed by the Beaujon index, with determination of a relative improvement rate. Results were analyzed according to clinical symptoms, fused level, previous surgery, association to posterior osteosynthesis and MRI changes. MRI changes were classified according to Modic types. RESULTS: The average relative improvement rate was 66 per cent. Pain topography, previous surgery, fused level, association with posterior osteosynthesis had not statistical effect on the functional result. Inversely, a close relation was observed between pre-operative MRI changes and the result of surgery: best results were observed in Modic I changes on adjacent vertebral end plates, with decreased signal of T1 and increased signal on T2 weighted images, suggesting inflammatory changes; poor results were observed in isolated disc degeneration without vertebral end-plates changes; poor results were observed in Modic II changes with increased signal on both T1 and T2 weighted images, suggesting degenerative changes; but among 5 non unions, 3 were observed in Modic II changes. DISCUSSION: The authors identify a lumbar disc dysfunction syndrome characterized by mechanical pain, with disc narrowing and anterior condensation of the vertebral plates on MRI (Modic I changes). This syndrome should be differentiated from common degenerative disc disease, without vertebral plates abnormalities (the "black disc" on MRI). CONCLUSION: Anterior fusion is effective for the treatment of low-back pain due to degenerative disc disease, when associated to vertebral plate changes; as the pathology is mainly anterior. We prefer an anterior mini-invasive approach; furthermore, posterior elements are intact and canal exploration is unnecessary. However, an additional posterior osteosynthesis is preferable in Modic type II, as non union rate is increased by fatty degenerative involution.

Effects of fatty acids on human platelet glutathione peroxidase: possible role of oxidative stress.

Highly polyunsaturated fatty acids of the n-3 family are known to be inhibitors of platelet functions, but these fatty acids (FA) may alter the platelet antioxidant status, depending on their concentrations. The present study was aimed to investigate the effect of various FA on glutathione-dependent peroxidase (GPx), the required antioxidant enzyme for degrading FA hydroperoxides. Human platelets were enriched in vitro with either n-3 (18:3, 20.5, or 22.6), n-6 (18:2 or 18:3) FA, 18:1 n-9 or 16:0, and the GPx activity was then measured. It was found that n-3 FA enhanced the GPx activity whereas the others did not affect the enzyme activity. The increased GPx activity was associated with an increased amount of the enzyme measured by Western blotting. The enhanced activity and amount of GPx induced by 22:6n-3, the most potent activator among the n-3 FA, was completely abolished in the presence of cycloheximide at a concentration known to inhibit platelet protein synthesis. Because platelets are devoid of nucleus, which rules out the involvement of transcriptional factors, this suggests that 22:6n-3 might act at a translational level. On the other hand, 22:6n-3 treatment increased the malondialdehyde formation and decreased the vitamin E level in platelets, both events that could be prevented by the antioxidant epicatechin. Because epicatechin also suppressed the enhancement of both the activity and amount of GPx induced by 22:6n-3, we conclude that the increased GPx activity (possibly via protein synthesis) might be associated with an oxidative stress induced by 22:6n-3 and/or 20:4n-6 released from the platelet endogenous pool in the course of the 22:6n-3 enrichment.

N-3 fatty acid-induced lipid peroxidation in human platelets is prevented by catechins.

The effects of catechins were studied in both unstimulated platelets and platelets submitted to a mild oxidative stress induced by docosahexaenoic acid (DHA). Human unstimulated platelets were incubated in the presence of catechin or epicatechin (1, 10 or 100 microM) for 2 h at 37 degrees C. Treatment by 1 microM epicatechin was sufficient to induce a significant inhibition (-30%) of basal thromboxane B2 formation. This result is consistent with the observed inhibitory effects of flavonoids on platelet aggregation. DHA treatment of platelets decreased the amount of alpha-tocopherol and increased the malondialdehyde (MDA) formation. The presence of epicatechin or catechin prevented the oxidative stress induced by DHA. Indeed, the platelet alpha-tocopherol level was significantly increased when compared to that of platelets treated by DHA alone, to reach the control level, whereas MDA was depressed to a level even lower than the control one. Our results indicate that catechin and especially epicatechin protect platelets from a peroxidative stress.

A method for specific analysis of free fatty acids in biological samples by capillary gas chromatography.

The present report describes a simple method to selectively extract free fatty acids and analyze them by capillary gas-liquid chromatography. The procedure is based on the use of fumed silicon dioxide. In the presence of plasma, this material induces a rapid rise in the viscosity of the mixture and presents the ability to trap large particles such as emulsified lipids and lipoproteins. Albumin-bound fatty acids are thus left in the aqueous media. We present applications of our procedure for the analysis of free fatty acids in 0.2 ml of plasma from rat or human. By comparison with the method utilizing thin-layer chromatography for the separation of fatty acids and gas chromatography analysis, the present method has been found to be reliable and simple. The recovery of linoleic acid was 92.1 +/- 8.2%, a value which is about twice better than that obtained with the procedure using thin-layer chromatography. In particular, long-chain polyunsaturated fatty acids were better preserved. Our procedure does not require the use of organic solvents and its simplicity and reproducibility make it suitable for routine specific determination of the composition of free fatty acids in biological samples.

Effect of vitamin E on acute iron load-potentiated aggregation, secretion, calcium uptake and thromboxane biosynthesis in rat platelets.

In the present study performed on rats, we investigated the influence of an in vivo acute iron load on several platelet parameters and their modification after vitamin E supplementation. Iron load was achieved by injecting iron dextran corresponding to 0.1 mg Fe3+ per kg in the gluteus muscles. Control rats were injected with an equal amount of a dextran solution. Analyses were performed 18 h after injection. By comparison with controls, in iron-injected animals, we found significant increases of: (1) serum total iron (by 110%); (2) aggregation of isolated platelets induced by low concentration of thrombin and ADP (by 350% and 120%, respectively); (3) thrombin-induced endogenous serotonin secretion (by 94%). We also studied the mobilization of radiolabeled arachidonate preincorporated into platelet phospholipids. The results indicated that the thrombin-stimulated release of arachidonate and formation of cyclooxygenase and lipoxygenase products (particularly thromboxane B2), were significantly increased. We also found in plasma an increase (by 67%) of malondialdehyde (MDA) as well as a decrease of vitamin E (by 60%). When vitamin E was injected the day before iron injection, platelet hyperactivity and thromboxane biosynthesis were reduced as well as the plasma MDA concentration. Consequently, given the key role of calcium flux in the activation processes in platelets, we also investigated the thrombin-induced Ca2+ uptake by means of radiocalcium. We found that in platelets from iron-treated rats the Ca2+ uptake amounted to 3670 +/- 201 pmol/10(9) platelets (plt) and was significantly different from controls (1680 +/- 192 pmol/10(9) plt, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)