[ST elevation myocardial infarction in young adults: Is there an interest for thrombophilia screening?] / Syndrome coronarien aigu avec sus-décalage du segment ST chez les jeunes adultes : le bilan de thrombophilie a-t-il un intérêt ?

BACKGROUND: Coronary lesions characteristics as well as patient thrombogenicity can explain coronary events manifestation. In young patient, local conditions are usually less important and thrombogenicity could play a significant role. Assessing thrombophilia could be justified in young patients and may induce an adapted therapeutic management. PURPOSE: We aimed to assess the prevalence of thrombophilia and therapeutic modification in young adults aged≤55 years admitted in our department for ST elevation myocardial infarction (STEMI). METHODS: From January 2013 to January 2017, data on all patients aged≤55 years with STEMI admitted in emergency were retrospectively retrieved from our database. Thrombophilia investigation was made regarding clinical (with or without cardiovascular risk factors [CVRF]), biological and/or angiographic evaluation. RESULTS: A total of 133 patients aged≤55 years with STEMI were included. Cardiac arrest occurred in 15 patients (11%). One or less CVRF were found in 47 patients (35%). Smoking was reported in 93 patients (70%) and drug addiction (cannabis, cocaine) in 19 patients (14%). A subset of 51 patients (38%) were screened for thrombophilia. Patients with thrombophilia assessment were younger, less active smokers and presented less CVRF than patients without investigation (P<0.001). Single vessel diseased was found in 88 patients (66%). No differences regarding coronary procedural characteristic were found between the two groups. The most frequently encountered aetiology, found in 122 patients (92%), was de novo intra-arterial thrombosis related to atherosclerosis. In patients with thrombophilia assessment (n=51), one or more abnormal biological results was found in 22 patients (43%) and a therapeutic adjustment was made in 6 patients (12%). CONCLUSION: Thrombophilia screening in young STEMI adults showed an abnormality in 43% of cases. Antithrombotic treatment can be modified after its demonstration.

Molecular cloning and expression of mouse and human cDNAs encoding heparan sulfate D-glucosaminyl 3-O-sulfotransferase.

The cellular rate of anticoagulant heparan sulfate proteoglycan (HSPGact) generation is determined by the level of a kinetically limiting microsomal activity, HSact conversion activity, which is predominantly composed of the long sought heparan sulfate D-glucosaminyl 3-O-sulfotransferase (3-OST) (Shworak, N. W., Fritze, L. M. S., Liu, J., Butler, L. D., and Rosenberg, R. D. (1996) J. Biol. Chem. 271, 27063-27071; Liu, J., Shworak, N. W., Fritze, L. M. S., Edelberg, J. M., and Rosenberg, R. D. (1996) J. Biol. Chem. 271, 27072-27082). Mouse 3-OST cDNAs were isolated by proteolyzing the purified enzyme with Lys-C, sequencing the resultant peptides as well as the existing amino terminus, employing degenerate polymerase chain reaction primers corresponding to the sequences of the peptides as well as the amino terminus to amplify a fragment from LTA cDNA, and utilizing the resultant probe to obtain full-length enzyme cDNAs from a lambda Zap Express LTA cDNA library. Human 3-OST cDNAs were isolated by searching the expressed sequence tag data bank with the mouse sequence, identifying a partial-length human cDNA and utilizing the clone as a probe to isolate a full-length enzyme cDNA from a lambda TriplEx human brain cDNA library. The expression of wild-type mouse 3-OST as well as protein A-tagged mouse enzyme by transient transfection of COS-7 cells and the expression of both wild-type mouse and human 3-OST by in vitro transcription/translation demonstrate that the two cDNAs directly encode both HSact conversion and 3-OST activities. The mouse 3-OST cDNAs exhibit three different size classes because of a 5'-untranslated region of variable length, which results from the insertion of 0-1629 base pairs (bp) between residues 216 and 217; however, all cDNAs contain the same open reading frame of 933 bp. The length of the 3'-untranslated region ranges from 301 to 430 bp. The nucleic acid sequence of mouse and human 3-OST cDNAs are approximately 85% similar, encoding novel 311- and 307-amino acid proteins of 35,876 and 35,750 daltons, respectively, that are 93% similar. The encoded enzymes are predicted to be intraluminal Golgi residents, presumably interacting via their C-terminal regions with an integral membrane protein. Both 3-OST species exhibit five potential N-glycosylation sites, which account for the apparent discrepancy between the molecular masses of the encoded enzyme (approximately 34 kDa) and the previously purified enzyme (approximately 46 kDa). The two 3-OST species also exhibit approximately 50% similarity with all previously identified forms of the heparan biosynthetic enzyme N-deacetylase/N-sulfotransferase, which suggests that heparan biosynthetic enzymes share a common sulfotransferase domain.

Fucans, sulfated polysaccharides extracted from brown seaweeds, inhibit vascular smooth muscle cell proliferation. I. Comparison with heparin for antiproliferative activity, binding and internalization.

Smooth muscle cell (SMC) proliferation is inhibited both in vivo and in vitro by heparin. However, the precise mechanisms of action are still not understood. The analogy between two sulfated polysaccharides, heparin and fucan, has led us to compare in detail their effects on SMC growth. We have prepared and characterized a 19 kDa fucan fraction from brown seaweed, Ascophyllum nodosum. Fucan affects the growth of SMCs in a time- and dose-dependent, reversible and non-toxic fashion. As determined by cell counting, [3H]thymidine incorporation, and microcytofluorimetry analysis, heparin was less active than fucan in inhibiting SMC growth. Fucan and heparin act by preferential blocking of G0/G1, thus decreasing the G0/S transition. Binding experiments with [125I]fucan indicated saturable, unlabeled-fucan displaceable binding sites with an apparent Kd of 30 nM. Moreover, displacement experiments performed with various polysaccharides revealed that antiproliferative compounds interacted with these membrane sites, but non-antiproliferative polysaccharides (dextran, chondroitin sulfate) did not, providing evidence of a correlation between binding to SMCs and their antiproliferative activity. When cells were exposed at 37 degrees C to a fluorescent 5-([4,6-dichlorotriazin-2-yl]-amino)fluorescein (DTAF)-fucan, internalization occurred and punctate vesicles were observed which accumulated rapidly in the perinuclear region as previously reported for heparin. Nuclear preparations (membranes + contents) of cultured SMCs previously incubated with radiolabeled heparin or fucan indicated the presence of radioactivity, suggesting an antiproliferative action of both polysaccharides at the nuclear level. Collectively, these observations indicated that fucan and heparin share some similar mechanisms of action, such as SMC growth inhibition, binding, and internalization. In the accompanying paper (Logeart et al., Eur. J. Cell Biol. 74, 1997, this issue), we describe the effect of fucans of different molecular weights and conclude that there is no direct link between polysaccharide degradation and the antiproliferative effect on SMCs.

Fucans, sulfated polysaccharides extracted from brown seaweeds, inhibit vascular smooth muscle cell proliferation. II. Degradation and molecular weight effect.

Fucan, a sulfated polysaccharide extracted from brown seaweeds, inhibits smooth muscle cell (SMC) proliferation with a higher antiproliferative activity than heparin (Logeart et al., Eur. J. Cell Biol. 74, 1997, this issue). In order to investigate the structure-activity relationship of fucan on SMC growth, we have prepared by size exclusion chromatography fucan fractions of various molecular masses ranging from 5.5 to 556 kDa. Our experiments showed that the antiproliferative activity is dependent on the molecular weight of the polysaccharide. The molecular weight threshold indicated that about 30 saccharidic units on fucan were necessary to give the antiproliferative activity on SMCs. A kinetics study of DNA synthesis using tritiated thymidine uptake was also performed with different molecular weight fucan fractions. Although all tested fractions acted as soon as the cells enter the first cell cycle, the duration and potency of action varied. Moreover, displacement experiments of iodinated fucan revealed that the low molecular fucan fraction interacted weakly with the binding sites. Finally, gel permeation chromatography of internalized radiolabeled heparin and fucans was performed with SMCs. A rapid degradation of internalized heparin was observed, whereas only low molecular weight fucan fractions were partially degraded by SMCs. Together, these results indicate the significance of molecular weight on the antiproliferative activity of fucans on SMCs, and might help to understand their mechanism of action. In addition, the degradation experiments with internalized heparin and fucans ruled out a direct link between polysaccharide degradation and the antiproliferative effect on SMCs.