7970301
Dynamic Correlation between Intrahost HIV-1 Quasispecies Evolution and Disease Progression
Quantifying the dynamics of intrahost HIV-1 sequence evolution is one means of uncovering information about the interaction between HIV-1 and the host immune system. In the chronic phase of infection, common dynamics of sequence divergence and diversity have been reported. We developed an HIV-1 sequence evolution model that simulated the effects of mutation and fitness of sequence variants. The amount of evolution was described by the distance from the founder strain, and fitness was described by the number of offspring a parent sequence produces. Analysis of the model suggested that the previously observed saturation of divergence and decrease of diversity in later stages of infection can be explained by a decrease in the proportion of offspring that are mutants as the distance from the founder strain increases rather than due to an increase of viral fitness. The prediction of the model was examined by performing phylogenetic analysis to estimate the change in the rate of evolution during infection. In agreement with our modeling, in 13 out of 15 patients (followed for 3–12 years) we found that the rate of intrahost HIV-1 evolution was not constant but rather slowed down at a rate correlated with the rate of CD4+ T-cell decline. The correlation between the dynamics of the evolutionary rate and the rate of CD4+ T-cell decline, coupled with our HIV-1 sequence evolution model, explains previously conflicting observations of the relationships between the rate of HIV-1 quasispecies evolution and disease progression.
3798043
Simulation and prediction of the adaptive immune response to influenza A virus infection.
The cellular immune response to primary influenza virus infection is complex, involving multiple cell types and anatomical compartments, and is difficult to measure directly. Here we develop a two-compartment model that quantifies the interplay between viral replication and adaptive immunity. The fidelity of the model is demonstrated by accurately confirming the role of CD4 help for antibody persistence and the consequences of immune depletion experiments. The model predicts that drugs to limit viral infection and/or production must be administered within 2 days of infection, with a benefit of combination therapy when administered early, and cytotoxic CD8 T cells in the lung are as effective for viral clearance as neutralizing antibodies when present at the time of challenge. The model can be used to investigate explicit biological scenarios and generate experimentally testable hypotheses. For example, when the adaptive response depends on cellular immune cell priming, regulation of antigen presentation has greater influence on the kinetics of viral clearance than the efficiency of virus neutralization or cellular cytotoxicity. These findings suggest that the modulation of antigen presentation or the number of lung resident cytotoxic cells and the combination drug intervention are strategies to combat highly virulent influenza viruses. We further compared alternative model structures, for example, B-cell activation directly by the virus versus that through professional antigen-presenting cells or dendritic cell licensing of CD8 T cells.
43055872
Modeling T Cell Proliferation and Death in Vitro Based on Labeling Data: Generalizations of the Smith–Martin Cell Cycle Model
Abstract
The fluorescent dye carboxyfluorescein diacetate succinimidyl ester (CFSE) classifies proliferating cell populations into groups according to the number of divisions each cell has undergone (i.e., its division class). The pulse labeling of cells with radioactive thymidine provides a means to determine the distribution of times of entry into the first cell division. We derive in analytic form the number of cells in each division class as a function of time based on the distribution of times to the first division. Choosing the distribution of time to the first division to fit thymidine labeling data for T cells stimulated in vitro under different concentrations of IL-2, we fit CFSE data to determine the dependence of T cell kinetic parameters on the concentration of IL-2. As the concentration of IL-2 increases, the average cell cycle time is shortened, the death rate of cells is decreased, and a higher fraction of cells is recruited into division. We also find that if the average cell cycle time increases with division class then the qualify of our fit to the data improves.

13786750
Interpreting CFSE Obtained Division Histories of B Cells in Vitro with Smith–Martin and Cyton Type Models
The fluorescent dye carboxyfluorescin diacetate succinimidyl ester (CFSE) classifies proliferating cell populations into groups according to the number of divisions each cell has undergone (i.e., its division class). The pulse labeling of cells with radioactive thymidine provides a means to determine the distribution of times of entry into the first cell division. We derive in analytic form the number of cells in each division class as a function of time using the cyton approach that utilizes independent stochastic distributions for the time to divide and the time to die. We confirm that our analytic form for the number of cells in each division class is consistent with the numerical solution of a set of delay differential equations representing the generalized Smith–Martin model with cell death rates depending on the division class. Choosing the distribution of time to the first division to fit thymidine labeling data for B cells stimulated in vitro with lipopolysaccharide (LPS) and either with or without interleukin-4 (IL-4), we fit CFSE data to determine the dependence of B cell kinetic parameters on the presence of IL-4. We find when IL-4 is present, a greater proportion of cells are recruited into division with a longer average time to first division. The most profound effect of the presence of IL-4 was decreased death rates for smaller division classes, which supports a role of IL-4 in the protection of B cells from apoptosis.
25911131
Modeling sequence evolution in acute HIV-1 infection.
We describe a mathematical model and Monte Carlo (MC) simulation of viral evolution during acute infection. We consider both synchronous and asynchronous processes of viral infection of new target cells. The model enables an assessment of the expected sequence diversity in new HIV-1 infections originating from a single transmitted viral strain, estimation of the most recent common ancestor (MRCA) of the transmitted viral lineage, and estimation of the time to coalesce back to the MRCA. We also calculate the probability of the MRCA being the transmitted virus or an evolved variant. Excluding insertions and deletions, we assume HIV-1 evolves by base substitution without selection pressure during the earliest phase of HIV-1 infection prior to the immune response. Unlike phylogenetic methods that follow a lineage backwards to coalescence, we compare the observed data to a model of the diversification of a viral population forward in time. To illustrate the application of these methods, we provide detailed comparisons of the model and simulations results to 306 envelope sequences obtained from eight newly infected subjects at a single time point. The data from 68 patients were in good agreement with model predictions, and hence compatible with a single-strain infection evolving under no selection pressure. The diversity of the samples from the other two patients was too great to be explained by the model, suggesting multiple HIV-1-strains were transmitted. The model can also be applied to longitudinal patient data to estimate within-host viral evolutionary parameters.
26020494
Molecular mechanisms of deguelin-induced apoptosis in transformed human bronchial epithelial cells.
Increasing evidence has demonstrated that the phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway plays an important role in cell proliferation, apoptosis, angiogenesis, adhesion, invasion, and migration, functions that are critical to cancer cell survival and metastasis. Increased expression of activated Akt has been observed in the early stages of tobacco-induced lung carcinogenesis. Moreover, blocking the PI3K/Akt pathway specifically inhibits the proliferation of non-small cell lung cancer (NSCLC) cells, indicating that the PI3K/Akt pathway is a potential target for chemoprevention and therapy in lung cancer. The aim of this work is to study the lung cancer chemopreventive potential of PI3K/Akt inhibitors using an in vitro lung carcinogenesis model. We found that genetic or pharmacologic approaches targeting the PI3K/Akt pathway inhibited the proliferation of premalignant and malignant human bronchial epithelial (HBE) cells. After screening several natural products to identify a potential lung cancer chemopreventive agent, we have found that deguelin, a rotenoid isolated from Mundulea sericea (Leguminosae), specifically inhibits the growth of transformed HBE and NSCLC cells by inducing cell-cycle arrest in the G2/M phase and apoptosis, with no detectable toxic effects on normal HBE cells, most likely due to the agent's ability to inhibit PI3K/Akt-mediated signaling pathways. The specific sensitivity of premalignant and malignant HBE and NSCLC cells to deguelin suggests that this drug could be clinically useful for chemoprevention in early-stage lung carcinogenesis and for therapy in confirmed lung cancer.
21885090
Quantitative and qualitative profiling of mitochondrial DNA length heteroplasmy.
Quantitative and qualitative analysis of mitochondrial DNA length heteroplasmy for the first hypervariable segment (HV1) and second hypervariable segment (HV2) regions were performed using size-based separation of fluorescently-labeled polymerase chain reaction (PCR) products by capillary electrophoresis. In this report, the relative proportions of length heteroplasmies in individuals were determined, and each length variant in the heteroplasmic mtDNA mixture was identified. The study demonstrated that 36% and 69% of Koreans show length heteroplasmy in the HV1 and HV2 regions, respectively. Electropherograms revealed that length heteroplasmy in the HV1 region resulted in over 5 length variants in an individual. The peak patterns of length heteroplasmy in the HV1 region were classified into five major types. In the HV2 region, length heteroplasmy resulted in 3-6 length variants in an individual, and showed seven variant peak patterns. The increased knowledge concerning mtDNA length heteroplasmy is believed to not only offer a useful means of determining genetic identity due to increased mitochondrial DNA haplotype diversity by allowing mtDNAs to be classified into several peak patterns, but also represent a promising tool for the diagnosis of several common diseases which are etiologically or prognostically associated with mtDNA polymorphisms.
5859588
Volume-Based Parameter of 18F-FDG PET/CT in Malignant Pleural Mesothelioma: Prediction of Therapeutic Response and Prognostic Implications
BackgroundTo evaluate the importance of assessing volume-based parameter of 18F-FDG PET/CT in patients with malignant pleural mesothelioma (MPM) for the prediction of response and patient outcome early in the course of treatment.Materials and MethodsPatients (n = 13; M:F = 9:4, mean age, 54 years) with histopathologically proven MPM, all of whom were scheduled to undergo curative extrapleural pneumonectomy (EPP) or palliative chemotherapy, were included in this study. They were evaluated using integrated 18F-FDG PET/CT at baseline. Maximum standardized uptake value (SUVmax), average SUV (SUVavg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured using PET/CT data. Relationships between tumor progression and PET parameters were statistically analyzed.ResultsOf the 13 patients, 8 (62%) developed disease recurrence after surgery or tumor progression after chemotherapy (median follow-up, 329 days; range, 28–536 days). Between subgroups with and without tumor progression, significant differences were noted in MTV (P = 0.045). On ROC curve analysis, MTV (AUC = 0.850, 95% confidence interval [95% CI] 0.550–0.977) and TLG (AUC = 0.800, 95% CI 0.494–0.960) showed good predictive performance for tumor progression. Multivariate analysis adjusted for treatment modality showed that MTV (HR 1.003, P = 0.025) and TLG (HR 1.001, P = 0.031) were independent factors associated with tumor progression. Time to tumor progression was shorter in patients with a high volume-based parameter of PET than in those with a low value.ConclusionsVolume-based parameters of 18F-FDG PET/CT have the potential to provide prognostic information in MPM patients who are receiving surgery or palliative chemotherapy.
6681430
Haplotypes and mutation analysis of 22 Y-chromosomal STRs in Korean father–son pairs
We analyzed 369 Korean father/son haplotype transfers in 355 families at 22 Y-STRs (DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS385, DYS388, DYS437, DYS438, DYS439, DYS446, DYS447, DYS448, DYS449, DYS456, DYS458, DYS464, DYS635, and GATA H4.1). A total of 350 haplotypes were observed with an overall haplotype diversity of 0.9999. Among these, 345 were unique and five were found twice. Furthermore, 36 mutations were identified, giving locus-specific mutation rate estimates between 0.0 and 19.0 × 10−3 per generation and an average mutation rate estimate of 3.9 × 10−3 (95% CI 2.7–5.4 × 10−3). The compilation of Y-STR mutation events for the present study and previous studies demonstrates that DYS449, DYS458, DYS635, DYS456 and DYS439 are the most prone to mutations and that their overall average mutation rate estimate is 2.36 × 10–3 (95% CI 2.03–2.73 × 10–33).
44677500
Interaction of pitch and duration processing by non-musicians in reading musical notation.
To study the relation of pitch and duration processing in reading musical notation, a Stroop-like task was used by 20 non-musicians. A probe display was presented before each target note. Participants were required to process the tonal and metric information of the probe and then to make a match or mismatch decision between probe and target. The target's color informed participants which dimension (pitch or duration) required analysis. The congruity of the irrelevant dimension of the target was manipulated to examine the effect on the relevant dimension. The interference effect of the irrelevant dimension on the relevant dimension was obvious for number of errors and reaction times. This result is consistent with pitch and duration being processed interdependently and reconciles with the theory of dynamic attention.