Validity and Accuracy of Resonance Shift Prediction Formulas for Microcantilevers: A Review and Comparative Study

<p>This article provides a review of methods of predicting mass-induced resonance shifts in microcantilevers. It combines a review of factors that influence resonance frequency shifts, such as material properties, size effects, and support compliance with a comparative study of accuracy of predicting resonance shifts due to mass adsorption. The applicability and accuracy of widely used formulas to correlate mass addition with resonance shift are assessed through comprehensive comparison with experimental measurements and numerical methods. The methods include both distributed parameter and lumped parameter formulations. The applications include distributed added masses, tip masses, and added mass at arbitrary locations along a cantilever span.</p

Cross Reactive Cellular Immune Response to HCV Genotype 1 and 4 Antigens among Genotype 4 Exposed Subjects

<div><p>Background</p><p>Hepatitis C Virus (HCV) infection is a global health burden particularly in Egypt, where HCV genotype 4a (GT-4a) predominates. The prevention and control of HCV infection will remain a challenge until the development of an effective vaccine that protects against different genotypes. Several HCV GT-1-based vaccines are in different stages of clinical trials, but antigenic differences could make protection against other genotypes problematic. In this regard, data comparing the cell-mediated immune (CMI) response to different HCV genotypes are limited. We aimed to <i>ex vivo</i> investigate whether GT-1-based vaccine may protect against HCV GT-4 infections. This was carried out on samples collected from genotype 4 infected/exposed subjects.</p><p>Methods/Principal Findings</p><p>The CMI responses of 35 subjects; infected with HCV GT-4/or who had spontaneously-resolved the infection and 10 healthy control subjects; to two sets of seven HCV overlapping 15-mer peptide pools derived from both genotypes; and covering most of the viral proteins; were evaluated. This was carried out using an interferon gamma (IFNγ) enzyme-linked immunospot (ELISpot) assay. Peripheral blood mononuclear cells (PBMC) from 17 subjects (48%) responded to at least one peptide pool derived from GT-1b/GT-4a with 13 subjects responding to peptide pools from both genotypes. A strong correlation was found in the responses to both genotypes (<i>r</i> = 0.82, <i>p</i><0.001; 95% confidence interval = 0.562–0.933). The average IFNγ total spot forming cells (SFC)/10⁶ PBMC (±SE) from the responding subjects for GT-1b and GT-4a was 216±56 and 199±55, respectively (<i>p</i> = 0.833). Also, there were no significant differences between those who cleared their HCV infection or who remained HCV-RNA positive (<i>p</i> = 0.8).</p><p>Conclusion/Significance</p><p>Our data suggest that an effective GT-1b vaccine could protect from GT-4a infection. These data could help in HCV rationale vaccine design and efficacy studies and further our understanding of HCV cross protection against different genotypes.</p></div

High correlation between cell-mediated immune response to HCV-pooled peptides derived from genotypes 1b and 4a.

<p>PBMC isolated from Egyptians with chronic or resolved HCV infection were stimulated in triplicates with two sets of seven pooled overlapping 15-mer HCV genotype 1b, and genotype 4a peptide antigens (E2 through M) for 16 h as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101264#s2" target="_blank">Subjects and Methods</a> section. The total IFNγSFC recorded for each pool is shown for both genotypes. The total number of SFC for all responding donors to GT-4a pools was correlated with those from GT-1b in <b>Panel</b> (<b>A</b>) while that of resolved and chronic subjects are shown in <b>Panels</b> (<b>B</b>) and (<b>C</b>), respectively.</p

Demographic, clinical and laboratory characteristics of the study subjects.

<p>The subjects were classified as responders and non responders as defined in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101264#s2" target="_blank">Subjects and Methods</a> section. Specifically, responders and non-responders are those individuals who elicited or failed to elicit a positive HCV-specific IFNγ response in the ELISpot assay to one to fourteen HCV G-1b, and 4a overlapping 15-mer peptide pools, respectively. Ten healthy subjects with no known exposure to HCV served as a control group.</p><p>*Mean ± SD.</p