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2.  An SREBP Responsive micro-RNA Operon Contributes to a Regulatory Loop for Intracellular Lipid Homeostasis 
Cell metabolism  2013;18(1):51-61.
Sterol regulatory element binding proteins (SREBPs) have evolved as a focal point for linking lipid synthesis with other pathways that regulate cell growth and survival. Here, we have uncovered a polycistrionic micro-RNA locus that is activated directly by SREBP-2. Two of the encoded miRs, miR-182 and miR-96, negatively regulate expression of Fbxw7 and Insig-2 respectively, and both are known to negatively affect nuclear SREBP accumulation. Direct manipulation of this miR pathway alters nuclear SREBP levels and endogenous lipid synthesis. Thus, we have uncovered a new mechanism for regulation of intracellular lipid metabolism mediated by the concerted action of a pair of miRs that are expressed from the same SREBP-2 regulated miR locus and each targets a different protein of the multi-step pathway that regulates SREBP function. These studies reveal a miR “operon” analogous to the classic model for genetic control in bacterial regulatory systems.
PMCID: PMC3740797  PMID: 23823476
3.  Oral HPV infection in a clinic-based sample of Hispanic men 
BMC Oral Health  2014;14:7.
Human papillomavirus (HPV) is associated to the pathogenesis of various cancers, such as oropharyngeal squamous cell carcinoma, which has a high incidence in Puerto Rican men. Despite the burden of oral cancer in Puerto Rico, little is known about the epidemiology of oral HPV infection, particularly in high-risk men. Therefore, this study is aimed at determining the prevalence of oral HPV infection, the genotype distribution and correlates associated with oral HPV infection in men of at least 16 years of age attending a sexually transmitted infection (STI) clinic in Puerto Rico.
A cross-sectional study consisting of 205 men was conducted. Participants provided a 30-second oral rinse and gargle with mouthwash. Following DNA extraction, HPV genotyping was performed in all samples using Innogenetics Line Price Assay (INNO-LiPA). A questionnaire was administered, which included a demographic, behavioral and a clinical assessment. Descriptive statistics and bivariate analysis were used to characterize the study sample. Variables that achieved statistical significance in the bivariate analysis (p < 0.05) were assessed in multivariate logistic regression models.
The mean age of the study sample was 38.5 ± 14.2 years. Oral HPV prevalence among men was 20.0% (95.0%CI = 14.8%-26.1%) and of HPV type 16 was 2.4% (95.0%CI = 0.8%-5.6%). Oral HPV prevalence significantly increased over increasing age categories (p-trend = 0.001). Multivariate analysis showed that oral HPV was independently associated with number of sexual partners (adjusted OR = 1.02; 95%CI = 1.01-1.03) and lifetime use of cigarettes (adjusted OR = 3.00; 95%CI = 0.98-9.16).
Oral HPV among the sampled men in the STI clinic was high, regardless of the HIV status or sexual behavior. Interventions in STI clinics should include screening for HPV in the oral cavity for the early detection and reduction of long-term consequences of oral HPV infection, such as oropharyngeal cancer.
PMCID: PMC3906756  PMID: 24460642
Oral HPV infection; Epidemiology; High-risk men; STI/STD clinic; Puerto Rico
4.  Outcomes of Multidrug-Resistant Tuberculosis among Binational Cases in El Paso, Texas 
In the United States, multidrug-resistant tuberculosis (MDR-TB) is more commonly seen among foreign-born patients. We report outcomes for 46 patients with MDR-TB who were born in Mexico and treated along the United States–Mexico border. According to our definition, 30 were cured, 3 showed treatment failure, 3 died, and 10 abandoned treatment. Multidrug-resistant tuberculosis can be successfully treated on an ambulatory basis.
PMCID: PMC2963969  PMID: 21036837
5.  Heats of Mixing Using an Isothermal Titration Calorimeter: Associated Thermal Effects 
The correct determination of the energy generated or absorbed in the sample cell of an Isothermal Titration Calorimeter (ITC) requires a thorough analysis of the calorimetric signal. This means the identification and quantification of any thermal effect inherent to the working method. In this work, it is carried out a review on several thermal effects, studied by us in previous work, and which appear when an ITC is used for measuring the heats of mixing of liquids in a continuous mode. These effects are due to: (i) the difference between the temperature of the injected liquid and the temperature of the mixture during the mixing process, (ii) the increase of the liquid volume located in the mixing cell and (iii) the stirring velocity. Besides, methods for the identification and quantification of the mentioned effects are suggested.
PMCID: PMC2738902  PMID: 19742175
accuracy; excess enthalpies; isothermal titration calorimeter; liquid mixtures
6.  The effect of amino acid deletions and substitutions in the longest loop of GFP 
The effect of single and multiple amino acid substitutions in the green fluorescent protein (GFP) from Aequorea victoria has been extensively explored, yielding several proteins of diverse spectral properties. However, the role of amino acid deletions in this protein -as with most proteins- is still unknown, due to the technical difficulties involved in generating combinatorial in-phase amino acid deletions on a target region.
In this study, the region I129-L142 of superglo GFP (sgGFP), corresponding to the longest loop of the protein and located far away from the central chromophore, was subjected to a random amino acid deletion approach, employing an in-house recently developed mutagenesis method termed Codon-Based Random Deletion (COBARDE). Only two mutants out of 16384 possible variant proteins retained fluorescence: sgGFP-Δ I129 and sgGFP-Δ D130. Interestingly, both mutants were thermosensitive and at 30°C sgGFP-Δ D130 was more fluorescent than the parent protein. In contrast with deletions, substitutions of single amino acids from residues F131 to L142 were well tolerated. The substitution analysis revealed a particular importance of residues F131, G135, I137, L138, H140 and L142 for the stability of the protein.
The behavior of GFP variants with both amino acid deletions and substitutions demonstrate that this loop is playing an important structural role in GFP folding. Some of the amino acids which tolerated any substitution but no deletion are simply acting as "spacers" to localize important residues in the protein structure.
PMCID: PMC1919350  PMID: 17594481

Results 1-7 (7)