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Biomedical subjects

María J Gil

Publications and source records attributed to María J Gil.

13 recordsLinked to original sources
PubMed2006

Increased cardiovascular risk markers in obesity are associated with body adiposity: role of leptin.

Epidemiological studies have shown that obesity is associated with increased blood concentrations of proinflammatory factors and markers of endothelial dysfunction such as fibrinogen, C-reactive protein (CRP), and von Willebrand factor (vWF). We analyzed the association of these markers with percentage of body fat (BF), and the influence of leptin in a cross-sectional study of 1,089 subjects (366 men) aged 44 (34-53) [median (interquartile range)] years, who were classified as obese or nonobese according to BF estimated by whole-body air displacement plethysmography. Obesity was defined as BF >or= 25% in men and >or= 35% in women. Compared with non-obese subjects (mean +/- SD), obese patients had higher concentrations of fibrinogen (312 +/- 78 vs. 342 +/- 81 mg/dl, P < 0.001), CRP (0.41 +/- 0.75 vs. 0.75 +/- 1.04 mg/l, P = 0.014), vWF (107 +/- 29 vs. 123 +/- 55%, P < 0.001), and leptin (10.4 +/- 6.5 vs. 37.5 +/- 26.1 ng/ml, P < 0.0001). A positive correlation was observed between BF and fibrinogen (r = 0.266; P < 0.0001), logCRP (r = 0.409; P < 0.0001), and vWF (r = 206; P < 0.0001). Leptin was correlated with fibrinogen (r = 0.219, P < 0.0001), logCRP (r = 0., P < 0.0001), and vWF (r = 0.124, P = 0.002), but the statistical significance was lost after including BF in adjusted-correlation and multivariate analysis, suggesting that they are not regulated by leptin per se. In conclusion, the obesity-associated increase in the circulating concentrations of fibrinogen, CRP, and vWF is highly associated to BF and apparently not determined by leptin.

Adiposity↗
PubMed2005

Carbonic anhydrase inhibitors: inhibition of cytosolic/tumor-associated carbonic anhydrase isozymes I, II, and IX with benzo[b]thiophene 1,1-dioxide sulfonamides.

A series of selected benzo[b]thiophene-5- and 6-sulfonamide derivatives previously reported to show cytotoxic activity and some others newly synthesized has been tested for the interactions with several CA isozymes, some of which are known to be involved in tumorigenesis (hCA IX), whereas others are ubiquitously found in many normal tissues (the cytosolic isoforms hCA I and II). The unsubstituted sulfonamides inhibited hCA I with inhibition constants in the range of 63-138 nM, hCA II with inhibition constants in the range of 6.3-8.8 nM, and hCA IX with inhibition constants in the range of 2.8-15 nM, being thus more active than clinically used inhibitors such as acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide or indisulam (E 7070). Some of these derivatives also showed some selectivity for the inhibition of the tumor-associated (hCA IX) over the cytosolic isozyme hCA II. Although these derivatives may act on many targets other than the CAs (such as the NADH oxidase) or may induce apoptosis by accumulation of reactive oxygen species, it is quite important to try to decipher as many as possible of the potential mechanisms that lead to derivatives with potent antitumor activity in order to develop novel therapeutic strategies for the management of cancer.

Antigens, Neoplasm↗
PubMed2005

A flexible and versatile strategy for the covalent immobilization of chiral catalysts based on pyridinebis(oxazoline) ligands.

[reaction: see text] Flexible and versatile methods have been developed for the immobilization of chiral pyridinebis(oxazoline) ligands by covalent bonding to a solid support, either by grafting or by polymerization. Different spacers can easily be introduced to modulate the support-ligand distance and the electronic properties of the chiral ligand. As an example, 2,6-bis[(S)-4-isopropyloxazolin-2-yl]pyridine has been immobilized on polystyrene resins, both on a Merrifield-type resin by grafting and on supports prepared by polymerization of 4-vinyl-substituted ligands. The corresponding Ru complexes have been tested as catalysts in the cyclopropanation reaction between styrene and ethyl diazoacetate. The catalytic activity, the enantioselectivity, and the recyclability are strongly dependent on the catalyst preparation method and the total exclusion of oxygen and moisture in the filtration process. Under such optimized conditions, yields over 60% with up to 90% ee can be obtained in four successive reactions-the best cyclopropanation results described to date for a chiral solid ruthenium catalyst.

Journal Article↗
PubMed2004

Reduced adipose tissue mass and hypoleptinemia in iNOS deficient mice: effect of LPS on plasma leptin and adiponectin concentrations.

The aim of this study was to evaluate the impact of the lack of inducible NO synthase (iNOS) on body weight and adipose tissue mass as well as on plasma leptin and adiponectin in basal conditions and 6 h after lipopolysaccharide (LPS) administration in mice. Body weight was not different among male, six-week-old wild-type (WT) and iNOS-/- animals. However, the amount of epididymal white adipose tissue (EWAT) in iNOS-/- mice was significantly reduced (P<0.05). Circulating leptin and leptin mRNA in EWAT were decreased in iNOS-/- mice (P<0.05 and P<0.01, respectively). Plasma adiponectin and adiponectin mRNA were unchanged. LPS administration increased plasma leptin in both genotypes (P<0.05). Neither genotype nor treatment changed plasma adiponectin. In summary, iNOS-/- mice exhibited normal body weight but reduced adipose mass accompanied by hypoleptinemia. Leptin responsiveness to LPS in iNOS-/- mutants is preserved, showing that the LPS-induced rise in leptin is independent of the presence of functional iNOS. In addition, iNOS deficiency or LPS does not influence expression and circulating levels of adiponectin.

Adiponectin↗
PubMed2004

Theoretical insights into the role of a counterion in copper-catalyzed enantioselective cyclopropanation reactions.

The effect of a coordinating counteranion on the mechanism of Cu(I)-catalyzed cyclopropanation has been investigated extensively for a medium-sized reaction model by means of theoretical calculations at the B3LYP/6-31G(d) level. The main mechanistic features are similar to those found for the cationic (without a counteranion) mechanism, the rate-limiting step being nitrogen extrusion from a catalyst-diazoester complex to generate a copper-carbene intermediate. The cyclopropanation step takes place through a direct carbene insertion of the metal-carbene species to yield a catalyst-product complex, which can finally regenerate the starting complex. However, the presence of the counteranion has a noticeable influence on the calculated geometries of all the intermediates and transition structures. Furthermore, the existence of a preequilibrium with a dimeric form of the catalyst, together with a higher activation barrier in the insertion step, explains the lower yield of cyclopropane products observed experimentally in the presence of chloride counterion. The stereochemical predictions of a more realistic model (made by considering a chiral bis(oxazoline)-copper(i) catalyst) have been rationalized in terms of the lack of significant steric repulsions, and the model shows good agreement with the low enantioselectivities observed experimentally for these kinds of catalytic systems.

Journal Article↗
PubMed2004

Design, synthesis and biological evaluation of new potent 5-nitrofuryl derivatives as anti-Trypanosoma cruzi agents. Studies of trypanothione binding site of trypanothione reductase as target for rational design.

Design, using force-field calculations on the catalytic site of trypanothione reductase from Trypanosoma cruzi, has led to the development of new 5-nitrofuryl derivatives as potential anti-trypanosomal agents. The synthesized compounds were tested in vitro against T. cruzi and more than 75% of the prepared derivatives showed higher activity than nifurtimox. Compounds 5 and 11, hexyl 4-(5-nitrofurfurylidene)carbazate and N-hexyl 3-(5-nitrofuryl)propenamide, showed the highest in vitro trypanocidal effect reported to date for members of the nitrofuran family. Partition coefficients and energies for the single-electron reduction of compounds were theoretically determined. These properties could be not the major cause of the activities' differences. The physicochemical environment around E19, W22, C53 and Y111 residues within the trypanothione binding site of trypanothione reductase resulted a valuable target for the rational design of anti-trypanosomal drugs.

Animals↗
PubMed2003

Gene expression profile of omental adipose tissue in human obesity.

The aim of the present study was to gain insight into the pathophysiology of obesity by comparing the pattern of gene expression of omental adipose tissue of obese and lean volunteers using DNA microarrays. Omental adipose tissue biopsies were obtained by laparoscopic surgery from six male patients (44.2+/-6.3 yr). RNA was extracted and pooled for the obese (BMI: 37.3+/-2.5 kg/m2) and lean (BMI: 23.4+/-0.8 kg/m2) groups. From the total number of genes analyzed (1,152 well-characterized human genes), 41% were expressed at sufficient levels in human adipose tissue for detection in the microarray experiments, finding that 89 genes were up-regulated while 64 were down-regulated at least twofold in the omental adipose tissue obtained from obese patients. We found a general tendency to blunt lipolysis inducer genes and a global down-regulation of genes encoding growth factors. Moreover, an up-regulation in the expression of several mitogen-activated protein kinases (MAPKs) was observed. The down-regulation of genes involved in lipolysis activation may be involved in the etiopathogenesis of obesity. In addition, down-regulation of growth factors and the up-regulation of MAPKs may indicate an attempt to restrain adipocyte proliferation and differentiation. Furthermore, obesity is accompanied by an altered expression in omental adipose tissue of genes involved not only in energy homeostasis but also in quite diverse biological functions, such as immune response. The genomic approach underlines the importance of adipose tissue beyond energy metabolism.

Adipose Tissue↗
PubMed2003

Immobilizing a single pybox ligand onto a library of solid supports.

Chiral pyridinebis(oxazoline) (pybox) ligands can be efficiently immobilized onto silica through position 4 of the pyridine ring. The crucial intermediate in this strategy is 4-chloropybox, which is prepared in good yield from chelidamic acid. 4-Chloropybox reacts with p-hydroxybenzaldehyde and p-aminophenol to give two intermediates (pybox-CHO and pybox-NH2) that allow to introduce the formyl and amino groups able to link to spacers with triethoxysilyl groups. The modified ligands and their ruthenium complexes are immobilized by grafting onto preformed silicas or, alternatively, the support is created by sol-gel synthesis using the functionalized chiral ligand as a silica monomer. In this way it is possible to create a library where the variation involves the support rather than the catalyst. The aim of this approach is to study the influence of different parameters, such as the textural properties of the support and the immobilization method, on the functionalization and catalytic performance. Some of the immobilized complexes are compared as heterogeneous catalysts in the cyclopropanation reaction of styrene with ethyl diazoacetate.

Combinatorial Chemistry Techniques↗
PubMed2002

The first immobilization of pyridine-bis(oxazoline) chiral ligands.

[formula: see text] A chiral pyridine-bis(oxazoline) ligand, functionalized with a vinyl group in the pyridine ring, can be polymerized with styrene and divinylbenzene to obtain supported chiral ligands. As proof of the usefulness of this supported ligands, the corresponding ruthenium complexes are catalysts for the cyclopropanation reaction of styrene with ethyl diazoacetate with up to 85% ee.

Journal Article↗
PubMed2002

Involvement of leptin in the association between percentage of body fat and cardiovascular risk factors.

OBJECTIVES: Recent epidemiologic studies have shown that obesity is associated with elevated blood concentrations of prothrombotic-proinflammatory factors and markers of endothelial dysfunction such as fibrinogen, C-reactive protein (CRP), von Willebrand factor (vWF), and homocysteine. We have assessed whether these markers are associated with percentage of body fat (BF), insulin sensitivity as well as with leptin concentrations. DESIGN AND METHODS: Twenty-five men aged 49.6 +/- 12.7 yr (mean +/- SD) underwent whole-body air displacement plethysmography (Bod-Pod(R)) for estimating BF. Blood analyses for leptin and several other metabolic and cardiovascular markers were carried out. RESULTS: Obese subjects had higher levels as compared to controls of BF (37.5 +/- 5.1 vs. 26.0 +/- 6.6, p < 0.01), fibrinogen (3.30 +/- 0.43 vs. 2.67 +/- 0.11, p < 0.01), vWF (136.4 +/- 50.4% vs. 81.6 +/- 12.6%, p < 0.05), and leptin (17.6 +/- 8.7 vs. 6.2 +/- 3.3, p < 0.01), lower concentrations of HDL-cholesterol (1.09 +/- 0.20 vs. 1.51 +/- 0.10, p < 0.001) and lower QUICKI (1/[log(Ins(0)) + log(Glu(0))]) (0.31 +/- 0.03 vs. 0.34 +/- 0.02, p < 0.05). No significant changes were observed in CRP (5.7 +/- 3.4 vs. 3.8 +/- 1.6, p = 0.327) and homocysteine (9.4 +/- 4.2 vs. 8.3 +/- 0.9, p = 0.749). A positive correlation was observed between BF and fibrinogen (r = 0.67, p = 0.0003). Plasma leptin concentrations were correlated with fibrinogen (r = 0.71, p = 0.0001) and CRP (r = 0.43, p = 0.044). After adjustment for BF leptin emerged as a significant predictor of fibrinogen (beta = 0.47, p = 0.023; R(2) = 0.59, p < 0.001). QUICKI was positively correlated with HDL-cholesterol (r = 0.59, p = 0.010) and negatively with fibrinogen (r = -0.53, p = 0.025), CRP (r = -0.52, p = 0.028) and vWF (r = -0.56, p = 0.013). CONCLUSIONS: Increased BF and impaired insulin sensitivity are associated with increased concentrations of cardiovascular risk factors. Leptin seems to be involved in this elevation and emerges as a predictor of circulating fibrinogen concentrations.

Adipose Tissue↗
PubMed2002

Disruption of the leptin-insulin relationship in obese men 24 hours after laparoscopic adjustable silicone gastric banding.

BACKGROUND: The placement of a band to attain a tiny stomach pouch has been reported to produce early satiety in patients undergoing gastric banding. The adipocyte-derived hormone, leptin, has been shown to decrease both food intake and body weight. The aim of the present study was to assess the potential involvement of acute changes in leptin concentrations following laparoscopic adjustable silicone gastric banding (LASGB). METHODS: The study groups comprised obese male patients undergoing bariatric surgery by LASGB and overweight men undergoing laparoscopic Nissen fundoplication (NFd). Blood was drawn before surgery and 24 hours postoperatively for glucose, insulin and leptin measurements. RESULTS: In both experimental groups, a statistically significant decrease was observed in pre- and postsurgery glucose (LASGB 111 +/- 8 vs 99 +/- 6 mg/dl, P < 0.01; NFd 107 +/- 7 vs 98 +/- 5 mg/d, P < 0.01) and insulin concentrations (LASGB 39.8 +/- 11.9 vs 32.9 +/- 10.3 U/l, P < 0.01; NFd 13.2 +/- 3.3 vs 12.2 +/- 2.9 U/l, P < 0.05). However, no significant differences were observed when the percent change from pre-surgery values was analysed between both groups. Following surgery, an increase in leptin concentrations was observed in the LASGB group (23.5 +/- 4.7 vs 37.5 +/- 6.8 micrograms/l, P < 0.001) whereas a small decrease was evident in the NFd patients (12.9 +/- 4.6 vs 8.9 +/- 2.2 micrograms/l, P < 0.01). CONCLUSION: These findings strongly suggest that the short-term increase observed in plasma leptin concentrations following LASGB may play a key role in triggering an early satiety signal due to the modification of the gastrointestinal anatomy and physiology.

Adult↗