Carlos Alberto Vargas

Updated Frequency of EGFR and KRAS Mutations in NonSmall-Cell Lung Cancer in Latin America: The Latin-American Consortium for the Investigation of Lung Cancer (CLICaP)

Introduction: Previously, we reported the frequency of epidermal growth factor receptor (EGFR) and KRAS mutations in nonsmall-cell lung cancer (NSCLC) patients in Latin America. The EGFR mutation frequency was found between Asian (40%) and Caucasian (15%) populations. Here, we report the updated distribution of NSCLC mutations. Methods: A total of 5738 samples from NSCLC patients from Argentina (1713), Mexico (1417), Colombia (1939), Peru (393), Panama (174), and Costa Rica (102) were genotyped for EGFR and KRAS. Results: The median patient age was 62.2 ± 12.3 years; 53.5% were women, 46.7% had a history of smoking, and 95.2% had adenocarcinoma histology. The frequency of EGFR mutations was 26.0% (95% confidence interval [CI], 24.9–27.1; Argentina, 14.4% [12.8–15.6]; México, 34.3% [31.9–36.7]; Colombia, 24.7% [22.8–26.6]; Peru, 51.1% [46.2–55.9]; Panamá, 27.3 [20.7–33.9]; and Costa Rica, 31.4% [22.4–40.4]). The frequency of KRAS mutations was 14.0% (9.1–18.9). In patients with adenocarcinoma, EGFR mutations were independently associated with gender (30.7% females vs. 18.4% males; p < 0.001), nonsmoker status (27.4% vs. 17.1%, p < 0.001), ethnicity (mestizo/indigenous, 35.3% vs. Caucasian, 13.7%, p < 0.001), and the absence of KRAS mutation (38.1% vs. 4.7%; p < 0.001). The overall response rate to EGFR tyrosine kinase inhibitors was 60.6% (95% CI, 52–69), with a median progression-free survival and overall survival of 15.9 (95% CI, 12.420.6) and 32 months (95% CI, 26.5–37.6), respectively. Conclusion: Our findings support the genetic heterogeneity of NSCLC in Latin America, confirming that the frequency of EGFR mutations is intermediate between that observed in the Asian and Caucasian populations.

Distribution and trends of hematology and oncology research in Latin America: A decade of uncertainty

Although hematology and oncology research is a highly relevant and evolving field, research contributions by Latin American countries, apart from Brazil, remain unclear.

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs) under Static Loading Conditions

Conductive polymer composites are manufactured by randomly dispersing conductive particles along an insulating polymer matrix. Several authors have attempted to model the piezoresistive response of conductive polymer composites. However, all the proposed models rely upon experimental measurements of the electrical resistance at rest state. Similarly, the models available in literature assume a voltage-independent resistance and a stress-independent area for tunneling conduction. With the aim of developing and validating a more comprehensive model, a test bench capable of exerting controlled forces has been developed. Commercially available sensors—which are manufactured from conductive polymer composites—have been tested at different voltages and stresses, and a model has been derived on the basis of equations for the quantum tunneling conduction through thin insulating film layers. The resistance contribution from the contact resistance has been included in the model together with the resistance contribution from the conductive particles. The proposed model embraces a voltage-dependent behavior for the composite resistance, and a stress-dependent behavior for the tunneling conduction area. The proposed model is capable of predicting sensor current based upon information from the sourcing voltage and the applied stress. This study uses a physical (non-phenomenological) approach for all the phenomena discussed here.

Boundary element approaches for filling simulations of anisotropic reinforced preforms used in the resin transfer molding process

The boundary element method (BEM) is implemented in the simulation of the filling of anisotropic fiber reinforced preforms used in the resin transfer molding process (RTM). They are analyzed both as a homogeneous and a non-homogeneous domain. In the former case, two injection regimes are considered: constant pressure and constant flow. The BEM results of flow front positions, pressure history and pressure profiles in the two main directions of permeability are compared to analytical and experimental results. In the second case of non-homogeneous domain, the domain integral appearing in the boundary integral formulation is treated by the dual reciprocity (DR) technique; the DR-BEM results of the curve pressure versus radial distance Pressure vs. Radial distance in the main directions of permeability are compared to numerical results obtained from the solution of the equation of pressure using MacLaurin series. In this case, the influence of the linear radial change of the fiber volume fraction on the flow front positions and on the curves of pressure versus radial distance is analyzed Pressure vs. Radial distance. For the homogeneous case, an acceptable coincidence between BEM and analytical results is appreciated as the circular inlet effect, which is considered in the BEM formulation and is not considered in the analytical method, lessens with the time. In non-homogeneous case, the coincidence among the DR-BEM and the numerical MacLaurin series results indicates that the DR-BEM is a promising technique to deal with the infiltration phenomenon of anisotropic reinforced preforms in non-homogeneous domains.