Interethnic variation of the MMP-9 microsatellite in Amerindian and Mexican Mestizo populations: considerations for genetic association studies.

We studied the interethnic variation of the MMP-9 microsatellite in the Mestizo and Amerindian populations using blood samples collected from 435 healthy unrelated individuals from the Central Valley of Mexico. DNA samples were genotyped using the -90 (CA)12-27 repeat near the MMP transcriptional start site using capillary electrophoresis. Our data were compared with those from African, Asian, and European populations (N = 729). Both Mestizo and Amerindian populations were in Hardy-Weinberg equilibrium (P ≥ 0.05). However, strong genetic heterogeneity was found within the Mestizo population (94%, P ≤ 0.0001), which exhibited the highest frequency of Amerindian, African, and European alleles. Likewise, Amerindians showed 6.7% variation among populations (P ≤ 0.0001), suggesting a genetic substructure potentially associated with linguistic affiliations. These findings were corroborated with principal component and population differentiation analyses, which showed relative proximity among the Mestizos and their historical parental populations: Asian (FST ≥ 0.05), European (FST ≥ 0.09), and African (FST ≥ 0.02). Nevertheless, important differences were found between Mestizo and Nahuas (P ≤ 0.0001), and between Mestizo and Me'Phaas (P ≤ 0.0001). These findings highlight the importance of determining local-specific patterns to establish the population variability of MMP-9 and other polymorphic markers. Validation of candidate markers is critical to identifying risk factors; however, this depends on knowledge of population genetic variation, which increases the possibility of finding true causative variants. We also show that dissimilar ethnic backgrounds might lead to spurious associations. Our study provides useful considerations for greater accuracy and robustness in future genetic association studies.

Photoinduced electron transfer fluorometric Hg(II) chemosensor based on a BODIPY armed with a tetrapod receptor.

From the great variety of BODIPY based-chemosensors able to determine Hg(2+), only a small portion has been applied to its determination in environmental and/or biological samples. The lack of studies on the analytical performance of the latter sensors makes interesting the development of investigations oriented to their possible analytical applications. The synthesis of a BODIPY derivative armed with a tetrapod receptor is described. The procedure is based on a previous publication, and the modifications performed to improve the synthesis include alternative procedures with different objectives, as the consecution of a multigram synthesis, improving the low yields of some of the previously proposed procedure steps, simplifying the experimental steps, achieving the desired purity requirements for use with analytical purposes, and enriching the characterization of the implied structures. The characteristics of its selectivity towards Hg(2+) have been investigated, and the OFF-ON fluorometric response, based on a photo-electron transfer (PET) mechanism, served as the base for the development of a method able to determine Hg(2+) in environmental waters at ng mL(-1) levels. The intrinsic fluorescence of the BODIPY core is inhibited and the probe exhibits a weak fluorescence (i.e. "OFF" state due to the deactivating PET effect). Upon complexation, Hg(2+) interacts with the lone-pair electrons on the nitrogen atoms of the receptor moiety so that the electronic transfer from the receptor to the photo-excited fluorophore is slowed down or switched off (i.e. "ON" state due to the suppression of the deactivating PET effect by coordination of the analyte to the probe). Regarding the complex photostability in aqueous solution, it is mandatory to conduct the experiments at darkness due to its photodegradation. The stoichiometry studies indicated a 1:2 relationship for the BODIPY-Hg(2+) complex. The high selectivity towards mercuric ions is considerably influenced by pH, being necessary to conduct the experiments in a pH value higher than 6. Calibration samples were prepared by adding appropriate amounts of Hg(2+) between 20.0-120.0 ng mL(-1), at a constant BODIPY concentration of 1 µmol L(-1). After agitating for 5 min at darkness, phosphate buffer (pH=7.50) was added, and it was diluted to the mark with water. Fluorescence measurements were carried out at 18 °C, exciting at 515 nm, and obtaining fluorescence emission at 538 nm. The method has been satisfactory applied to Hg(2+) determination in environmental water samples.

Enhanced MCR-ALS modeling of HPLC with fast scan fluorimetric detection second-order data for quantitation of metabolic disorder marker pteridines in urine.

This work presents the development of a liquid chromatographic method based on modeling entire fast scan fluorimetric detection second-order data with the multivariate curve resolution alternating least squares algorithm, for the simultaneous determination of five marker pteridines in urine samples. The modeling strategy involves the building of a single MCR-ALS model composed of matrices augmented in the spectral mode, i.e. time profiles remain invariant while spectra may change from sample to sample. This approach allowed us to separate and determine the whole analytes at once. The developed approach enabled us to determine five of the most important metabolic disorder marker pteridines: biopterin, neopterin, isoxanthopterin, pterin and xanthopterin, three of them presenting emission spectra with the same emission wavelength maxima. In addition, some of these analytes present overlapped time profiles. As a consequence of using the entire data sets, a considerable reduction of the data processing experimental time can be achieved. Results are compared with a previous strategy in which data were split in five different regions, and information about the figures of merit of the new strategy compared with the previously reported strategy is reported.

HLA Genes in Mayos Population from Northeast Mexico.

HLA class I and class II alleles have been studied in 60 unrelated people belonging to Mayos ethnic group, which lives in the Mexican Pacific Sinaloa State. Mayos HLA profile was compared to other Amerindians and worldwide populations' profile. A total of 14,896 chromosomes were used for comparisons. Genetic distances between populations, Neigbour-Joining dendrograms and correspondence analyses were performed to determine the genetic relationship among population. The new specific Mayo HLA haplotypes found are: HLA-A*02-B*35-DRB1*1406-DQB1*0301; HLA-A*02-B*48-DRB1*0404-DQB1*0302; HLA-A*24-B*51-DRB1*0407-DQB1*0302 and HLA-A*02-B*08-DRB1*0407-DQB1*0302. However, the typical Meso American HLADRB1*0407 represents a 40% of all DRB1 alleles. While common HLA characteristics are found in Amerindian distant ethnic groups, still new group specific HLA haplotypes are being found, suggesting that a common founder effect (i.e. high DRB1*0407) is noticed. Moreover, new HLA haplotypes are almost certainly appearing along time probably due to specific pathogen (?) selection for diversity. Mayo language is close to the Tarahumara one (another geographically close group); notwithstanding both groups are not genetically close according to our results, showing again the different evolution of genes and languages, which do not correlate. Finally, Sinaloa is one of the Mexican States in which more European genes are found. However, the results presented in this paper, where no European HLA genes are seen in Mayos, should have a bearing in establishing transplant programs and in HLA and disease studies.

LMP2 and LMP7 gene polymorphism in Mexican populations: Mestizos and Amerindians.

Low molecular weight polypeptide (LMP) genes are located within the major histocompatibility complex and have been associated with autoimmune diseases such as ankylosing spondylitis. In order to define the distribution of LMP genes in Mexican populations, the LMP2 and LMP7 polymorphism was analyzed in 312 Mexican individuals (95 Mexican Mestizos, 48 Nahuas, 56 Mazatecans, 50 Teenek, and 63 Mayos) belonging to different ethnic groups. In Mexican populations both Mestizos and Amerindians presented similar distribution of LMP2 and LMP7 polymorphisms, except Nahuas and Mayos who presented the higher frequencies of LMP2-H/H and the lowest frequencies of LMP2-H/R genotypes (P < 0.05 when compared with Mexican Mestizos). The LMP7-K/K genotype was absent in Nahuas, Teenek and Mayos and only one Mazatecan individual presented this genotype. Differences with other populations were found in Mexicans. An increased frequency of LMP2-H and a decreased frequency of LMP2-R alleles were observed in Mexican Amerindians (Nahuas and Mayos) when compared with Brazilian Amerindians (Kaingang and Guarani) and Caucasians (Spaniards) (P < 0.05). All Mexican populations (Mestizos and Amerindians) presented an increased frequency of LMP7-Q allele and a decreased frequency of LMP7-K allele when compared to Brazilian Amerindians (Kaingang), Caucasians (United States) and Asian (Japan) populations (P < 0.05). Genetic distances showed that Mexican Mestizos have an important relation with Spaniards and with all Mexican Amerindians. The present data corroborate the influence of Spaniard and Amerindian genes in the Mexican Mestizo population and could help to define the true significance of LMP polymorphism as genetic and evolutive marker in the Amerindian populations.

[Efficacy of clopidogrel as ADP-dependent platelet aggregation inhibitor. Study on individuals with coronary artery disease]. / Eficacia del clopidogrel como inhibidor de la agregación plaquetaria dependiente de ADP. Un estudio en individuos con enfermedad arterial coronaria.

Acetyl-salicylic acid inhibits thromboxane A2 production and reduces the risk of vascular occlusive events by 20 to 25%. Ticlopidine inhibits ADP-dependent platelet aggregation and reduces the same risk by 30 to 35%, but produces some adverse effects. Clopidogrel is a ticlopidin-derived antiplatelet-drug, with the same mechanism of action; reduces the expression of the glycoprotein IIb/IIIa, the fibrinogen receptor on the platelet surface. Clopidogrel has the same clinical efficacy of ticlopidin and lowers the incidence of adverse effects. In this study, we evaluated the effects of one daily dosis of 75 mg of clopidogrel on platelet function in 33 subjects with coronary artery disease. Before treatment and after the 6th and 12th week, the following parameters were evaluated: 5 microM-ADP and 20 micrograms/mL collagen-induced platelet aggregation, bleeding time and fibrinogen concentration. In basal and in the 6th and 12th week samples, ADP-induced platelet aggregation was 90.7% +/- 13.2, 54.6% +/- 23.2 and 49.2% +/- 23.7 respectively, that represents a significant reduction of 38.6% and 44.4%. Reduction of collagen-induced platelet aggregation was not significative. Plasmatic fibrinogen did not suffer variation during treatment. Bleeding time was significant prolonged from 4.1 minutes to 15.4 and 14.6 minutes (3.7-3.5 times compared with the test before treatment). There were no haemorrhagic complications, only digestive discomfort in fewer than 3% of patients. We concluded that clopidogrel is a safe and efficacious drug for patients, it efficiently reduces ADP-induced platelet aggregation and prolongs bleeding time.

Omentum flap versus pectoralis major flap in the treatment of mediastinitis.

The outcome of mediastinal reconstruction during the past 10 years at the "Instituto Nacional de Cardiología Ignacio Chávez" (INCIC), Mexico City was compared. A total of 7136 patients were submitted to open heart surgery. Eighty-two patients (1.15 percent) developed mediastinitis, and 33 patients (0.46 percent) developed sternal osteomyelitis. Only patients who developed mediastinitis with sternal osteomyelitis were included in the study. Reconstruction was performed either with a major omentum flap (12 patients) or a pectoralis major flap (21 patients). The sepsis-related mortality rate was higher in the pectoralis group (28.6 percent) than in the omentum group (0 percent) (p < 0.05). All of the postoperative deaths of the pectoralis group were caused by septic shock; in the omentum group, there were no such deaths. It is concluded that mediastinal reconstruction using the omentum flap in patients with mediastinitis secondary to open heart surgery is associated with fewer septic complications than using the pectoralis major flap.

Prothrombotic states in young people with idiopathic stroke. A prospective study.

BACKGROUND AND PURPOSE: Although 4% of cerebral infarcts in the young can be attributed to hematologic disturbances that predispose to thrombosis, the frequency of cerebral infarcts caused by prothrombotic states is not known. Recently, the association between cerebral infarction and deficiencies of elements of the natural anticoagulant system has been recognized. METHODS: Thirty-six consecutive patients under 40 years of age with cerebral infarction of undetermined cause were prospectively studied. Quantitation of natural anticoagulants was done at least 3 months after the cerebral infarction. The following activity tests were performed, all by the chromogenic method: antithrombin III, protein C, plasminogen, tissue plasminogen activator, and inhibitor of tissue plasminogen activator. Protein S was quantified by the Laurell rocket method. All patients underwent a complete cardiological examination, including two-dimensional echocardiography, as well as four-vessel cerebral angiography. Some patients were also studied by transesophageal echocardiography. RESULTS: Of 36 patients, 17 were male, with a mean age of 28 years. Mean age for women was 25 years. Nine patients (25%; 5 women, 4 men) had a deficiency of one natural anticoagulant and constituted group I. In these patients, isolated protein S deficiency was detected in five cases (13.8%); in one case, we observed the association between protein S deficiency and antiphospholipid antibodies; and deficiency of protein C was seen in one case (2.7%), of antithrombin III in one case (2.7%), and of plasminogen in one case (2.7%). Instances of cerebral infarction without natural anticoagulant deficiency (group II) included 12 women and 15 men. There were no differences in clinical and radiological findings between the two groups. CONCLUSIONS: Considering the importance of prothrombotic state, especially caused by deficiency of protein S, in the development of cerebral infarcts, we suggest that it should be looked for in every young patient affected by this pathological entity and in whom no etiologic factors can be determined.

[Effect of lead and cadmium on platelet aggregation]. / Efecto del plomo y cadmio sobre la agregación plaquetaria.

Two heavy metals, lead and cadmium, are frequently found as pollutants in many systems. Their effect upon platelet aggregation was investigated, both in human and rat platelet rich plasma and washed platelets. ADP-induced aggregation of human platelets was inhibited by 50%, using concentrations of free lead between 2-4 mM and free cadmium between 0.05 and 0.2 mM. Rat platelets were about ten times more sensitive to the effect of lead than human PRP. 50% inhibition of epinephrine-induced aggregation was attained at lower concentrations of metal, than the concentrations needed for ADP-induced aggregation. The effect was more apparent upon the first phase, which was lengthened, both with PRP and washed platelets. The aggregation of human and rat washed platelets by calcium was inhibited by concentrations of the metals within micromolar ranges. When A 23187 was used as the aggregating agent, the inhibition by the metals was only partial. Cysteine, at approximately tenfold concentrations, reversed the effect of the metals. Cadmium appeared more effective than lead as an inhibitor of platelet aggregation in all systems. Since only high levels of metal inhibit aggregation, more sensitive organs or systems would show alterations, due to these metals at an earlier stage and at lower concentrations.