RESUMEN
The synthesis of novel aluminyl anion complexes has been well exploited in recent years. Moreover, the elucidation of the structure and reactivity of these complexes opens the path toward a new understanding of low-valent aluminum complexes and their chemistry. This work computationally treats the substituent effect on aluminyl anions to discover suitable alternatives for H2 activation at a high level of theory utilizing coupled-cluster techniques extrapolated to the complete basis set. The results reveal that the simplest AlH2- system is the most reactive toward the activation of H2, but due to the low steric demand, severe difficulty in the stabilization of this system makes its use nonviable. However, the results indicate that, in principle, aluminyl systems with -C, -CN, -NC, and -N chelating centers would be the best choices of ligand toward the activation of molecular hydrogen by taking care of suitable steric demand to prevent dimerization of the catalysts. Furthermore, computations show that monosubstitution (besides -H) in aluminyl anions is preferred over disubstitution. So our predictions show that bidentate ligands may yield less reactive aluminyl anions to activate H2 than monodentate ones.
RESUMEN
INTRODUCTION: Two separate molecular pathways have been proposed for the early carcinogenic events observed in the oral cavity and pharynx: one is associated with chemical etiological factors such as smoking and drinking, and the other one is associated with HPV insertion. OBJECTIVE: A proof-of-principle study was performed to ascertain if global DNA methylation could be used to distinguish between the early molecular changes in premalignant oral lesions. METHODS: Personal histories of tobacco and alcohol use were obtained by questionnaire. HPV insertion in tumor tissue was detected by polymerase chain reaction (PCR). Global DNA methylation levels were obtained using HPLC for fraction separation and mass spectrometry for quantification. Predictive simulations were performed to explore potential associations between different etiological factors and the global DNA methylation index. Significance of results was ascertained using Pearson's Chi-squared test. RESULTS: The global methylation index was found to be 4.28 (95% CI, 4.1, 4.4) in an oral cancer case series. Pearson's chi squared test showed no statistically significant difference between cases that had smoking (p = 0.21), drinking (p = 0.31) or HPV insertion (p = 0.34) as etiologic risk factors, when compared to cases that did not. An inverse significant association between smoking and DNA methylation was observed. As the smoking effect increases, the global methylation index decreases, In addition, no associations between the probability of DNA methylation and drinking, or DNA methylation and HPV insertion were observed in simulations. CONCLUSIONS: The global DNA methylation index was shown to vary for oral cancer cases with different etiologies. Smoking was inversely correlated with DNA methylation levels when generalized linear model simulations were performed. Future studies should look at global DNA methylation alterations associated to the progression from normal to premalignant oral epithelium tissue in a cohort of smokers and nonsmokers.
Asunto(s)
Carcinoma de Células Escamosas/genética , Metilación de ADN , Neoplasias de la Boca/genética , Consumo de Bebidas Alcohólicas/efectos adversos , Carcinoma de Células Escamosas/etiología , Humanos , Modelos Genéticos , Neoplasias de la Boca/etiología , Infecciones por Papillomavirus/complicaciones , Fumar/efectos adversosRESUMEN
Little is known about hypertension in Haitians. We performed a pilot survey of ambulatory Haitian patients in a multispecialty clinic at a large public teaching hospital. Approximately 10% of the clinic population was of Haitian origin. Clinical data were collected on 88 consecutive Haitian patients. Of these 88, 77 (87.5%) were hypertensive (SBP > or = 140 or DBP > or = 90 mm Hg or taking antihypertensive medication). The characteristics of the hypertensive patients were: age 54.1 +/- 13.0 (s.d.) years; 27 men, 50 women; 12/64 (19%) smoked; 7/63 (11%) used alcohol. Diabetes was present in 21/77 (27%). In patients for whom height and weight were available, obesity was present in 52%. Using JNC V criteria, 18 (23%) had Stage 1, 16 (21%) Stage 2, 18 (23%) Stage 3, and 25 (33%) Stage 4 hypertension. Despite 63/77 (82%) being treated for hypertension, only 20 (26%) were controlled (< 140/< 90 mm Hg). Of those under treatment, 29 were taking one drug; 18 (two drugs); 12 (three drugs); and four (four drugs). Target organ damage was evident in 37 (48%), including coronary artery disease (8), CHF (6), chronic renal failure (15), stroke (9), and LVH by ECG (19). There was evidence of severe noncompliance in 32 (42%). We conclude that in this clinic sample, hypertension was highly prevalent and unusually severe in terms of blood pressure (BP) level, refractoriness to treatment, and target organ consequences. Further studies are indicated.