In 1980, Furchgott and Zawadzki demonstrated that the relaxation of vascular smooth muscle cells in response to acetylcholine is dependent on the anatomical integrity of the endothelium. Endothelium-derived relaxing factor was identified 7 years later as the free radical gas nitric oxide (NO). In endothelium, the amino acid L-arginine is converted to L-citrulline and NO by one of the three NO synthases, the endothelial isoform (eNOS). Shear stress and cell proliferation appear to be, quantitatively, the two major regulatory factors of eNOS gene expression. However, eNOS seems to be mainly regulated by modulation of its activity. Stimulation of specific receptors to various agonists (e.g., bradykinin, serotonin, adenosine, ADP/ATP, histamine, thrombin) increases eNOS enzymatic activity at least in part through an increase in intracellular free Ca2+. However, the mechanical stimulus shear stress appears again to be the major stimulus of eNOS activity, although the precise mechanisms activating the enzyme remain to be elucidated. Phosphorylation and subcellular translocation (from plasmalemmal caveolae to the cytoskeleton or cytosol) are probably involved in these regulations. Although eNOS plays a major vasodilatory role in the control of vasomotion, it has not so far been demonstrated that a defect in endothelial NO production could be responsible for high blood pressure in humans. In contrast, a defect in endothelium-dependent vasodilation is known to be promoted by several risk factors (e.g., smoking, diabetes, hypercholesterolemia) and is also the consequence of atheroma (fatty streak infiltration of the neointima). Several mechanisms probably contribute to this decrease in NO bioavailability. Finally, a defect in NO generation contributes to the pathophysiology of pulmonary hypertension. Elucidation of the mechanisms of eNOS enzyme activity and NO bioavailability will contribute to our understanding the physiology of vasomotion and the pathophysiology of endothelial dysfunction, and could provide insights for new therapies, particularly in hypertension and atherosclerosis.

Two isoforms of estrogen receptor (ER) have been described: ER␣ and ER␤. The initial gene targeting of ER␣, consisting in the introduction of a Neo cassette in exon 1 [␣ERKO, hereafter called ER␣-Neo KO (knockout)], was reported in 1993. More recently, another mouse deficient in ER␣ because of the deletion of exon 2 (ER␣KO, hereafter called ER␣-⌬2 KO) was generated. In ovariectomized ER␣-wild-type mice, estradiol (E2) increases uterine weight and basal production of endothelial nitric oxide (NO). Both of these effects are abolished in ER␣-⌬2 KO mice. In contrast, we show here that both of these effects of E 2 are partially (uterine weight) or totally (endothelial NO production) preserved in ER␣-Neo KO. We also confirm the presence of two ER␣ mRNA splice variants in uterus and aorta from ER␣-Neo KO mice. One of them encodes a chimeric ER␣ protein (ER␣55), partially deleted in the A͞B domain, that was detected in both uterus and aorta by Western blot analysis. The other ER␣ mRNA splice variant codes for an isoform deleted for the A͞B domain (ER␣46), which was detected in uterus of ER␣-Neo KO, and wild-type mice. This protein isoform was not detected in aorta. The identification of these two N-terminal modified isoforms in uterus, and at least one of them in aorta, probably explains the persistence of the E 2 effects in ER␣-Neo KO mice. Furthermore, ER␣-Neo KO mice may help in the elucidation of the specific functions of full-length ER␣ (ER␣66) and ER␣46, both shown to be physiologically generated in vivo.

Pseudomonas aeruginosa lung infections are a major cause of death in cystic fibrosis and hospitalized patients. Treating these infections is becoming difficult due to the emergence of conventional antimicrobial multiresistance. While monosaccharides have proved beneficial against such bacterial lung infection, the design of several multivalent glycosylated macromolecules has been shown to be also beneficial on biofilm dispersion. In this study, calix[4]arene-based glycoclusters functionalized with galactosides or fucosides have been synthesized. The characterization of their inhibitory properties on Pseudomonas aeruginosa aggregation, biofilm formation, adhesion on epithelial cells, and destruction of alveolar tissues were performed. The antiadhesive properties of the designed glycoclusters were demonstrated through several in vitro bioassays. An in vivo mouse model of lung infection provided an almost complete protection against Pseudomonas aeruginosa with the designed glycoclusters.

Abstract-Although estradiol (E 2 ) has been recognized to exert several vasculoprotective effects in several species, its effects in mouse vasomotion are unknown, and consequently, so is the estrogen receptor subtype mediating these effects. We investigated the effect of E 2 (80 g/kg/day for 15 days) on NO production in the thoracic aorta of ovariectomized C57Bl/6 mice compared with those given placebo. E 2 increased basal NO production. In contrast, the relaxation in response to ATP, to the calcium ionophore A23187, and to sodium nitroprusside was unaltered by E 2 , whereas acetylcholine-elicited relaxation was decreased. The abundance of NO synthase I, II, and III immunoreactive proteins (using Western blot) in thoracic aorta homogenates was unchanged by E 2 . To determine the estrogen receptor (ER) subtype involved in these effects, transgenic mice in which either the ER␣ or ER␤ has been disrupted were ovariectomized and treated, or not, with E 2 . Basal NO production was increased and the sensitivity to acetylcholine decreased in ER␤ knockout mice in response to E 2 , whereas this effect was abolished in ER␣ knockout mice. Finally, these effects of E 2 on vasomotion required long-term and/or in vivo exposure, as short-term incubation of aortic rings with 10 nmol/L E 2 in the isolated organ chamber did not elicit any vasoactive effects. In conclusion, this study demonstrates that ER␣, but not ER␤, mediates the beneficial effect of E 2 on basal NO production. Key Words: nitric oxide synthase Ⅲ endothelial cell Ⅲ estrogens Ⅲ estrogen receptor T he incidence of cardiovascular disease is higher in men than in premenopausal women but increases in postmenopausal women. Until recently, an abundance of epidemiological data suggested a role for estrogens in this atheroprotective effect. 1,2 However, the protective effects of estrogen on cardiovascular diseases has become controversial these last years. The Heart and Estrogen/progestin Replacement Study (HERS) recently demonstrated the failure of hormonal replacement therapy (HRT) to increase survival in secondary prevention. 3 Because long-term trials evaluating the effect of HRT in primary prevention will conclude in several years, it is important to get insight into the vascular effects and mechanisms in the meantime.The mechanism whereby this protection is attributable to favorable changes in blood lipids and lipoproteins accounts for approximatively one third of its effect, 1 but a number of studies in humans 4 as well as animals 5-7 strongly suggest a direct action on the arterial wall.Endothelium is now recognized to play a crucial role in the physiology of circulation. In particular, endothelium generates nitric oxide (NO). This free radical messenger inhibits platelet aggregation, interferes with mononuclear cell adhesion, and relaxes the underlying smooth muscle cells. 8 -10 NO is generated by a family of 3 isoenzymes: neuronal NOsynthase (type I), inducible NO-synthase (type II), and endothelial NO-synthase (type III). NO synthase (NOS) III activity can be ...