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.
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.
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.
35021176
Primary Epstein-Barr virus infection associated with Kikuchi's disease and hemophagocytic lymphohistiocytosis: a case report and review of the literature.
An association between hemophagocytic lymphohistiocytosis (HLH) and Kikuchi's disease is rarely seen in children. Here, we present the case of a male adolescent (age 16 years and 3 months) who suffered from spiking fever for more than 1 week, and multiple nodules over the neck and bilateral axilla for 2 months. A skin rash also developed over all four limbs, abdomen and face. Laboratory data and skin biopsy gave results compatible with a diagnosis of Kikuchi's disease. Hemophagocytosis in the bone marrow, hyper-triglyceridemia, elevated ferritin, and splenomegaly were also found, fulfilling the criteria for HLH. A recent primary Epstein-Barr virus infection was also diagnosed by serology. The patient ran a relatively benign course. Intravenous immunoglobulins, steroids or etoposide-containing regimens were not used, and his recovery was uneventful. A review of the literature showed that up to February 2009, 11 additional cases of Kikuchi's disease presenting simultaneously with, or mimicking, HLH had been reported. Complete resolution within several weeks, with no recurrence, was seen in all but one patient (a pregnant woman).
1467835
Time to follow up after an abnormal finding in organized gastric cancer screening in Korea
BackgroundThe prognosis for an abnormal medical finding is affected by both early detection and adherence to the presecribed schedule for follow-up examinations. In this study, we examined the time to follow up after an abnormal finding and determined the risk factors related to delays in follow up in a population-based screening program.MethodsThe study population consisted of patients who were newly diagnosed with gastric cancer through a gastric cancer screening program sponsored by the National Cancer Screening Program (NCSP) in 2005. Due to the skewed nature of the distribution of time to follow up, medians and interquartile ranges (IQR) are presented, and we analyzed the number of days preceding the follow-up time as a binary variable (≤90 days or >90 days). We used logistic regression analyses to evaluate the risk factors for a long delay.ResultsThe median number of days to follow-up initiation after an abnormal finding was 11 (IQR 7–27); 13.9% of the patients with gastric cancer obtained their follow-up evaluation more than 90 days. Age, type of health insurance, screening method, and screening results were risk factors for delays in follow up.ConclusionsThis study examined delays from the time of the discovery of an abnormal finding to time of the follow-up evaluation. Because inadequate follow up of abnormal exam results undermines the potential benefits of cancer screening, it is important to organize services that minimize delays between cancer screening and treatment.
5763830
Superior patient survival for continuous ambulatory peritoneal dialysis patients treated with a peritoneal dialysis fluid with neutral pH and low glucose degradation product concentration (Balance).
BACKGROUND
In recent years, laboratory and clinical research has suggested the need for peritoneal dialysis fluids (PDFs) that are more biocompatible than the conventional PDFs commonly used today. Bioincompatibility of PDF has been attributed to low pH, lactate, glucose, glucose degradation products (GDPs), and osmolality. PDFs with neutral pH and low GDPs are now available commercially. In vitro and early clinical studies suggest that these solutions are indeed more biocompatible but, as of now, there is no evidence that their use improves patient outcome.


METHODS
Using a dedicated database of over 2000 patients treated with PD in Korea, we were able to conduct a retrospective observational study comparing outcomes for incident continuous ambulatory PD patients treated with a standard, conventional, heat-sterilized PDF to the outcomes for patients treated with a novel, low GDP, neutral-pH PDF prepared in a dual-compartment, double-bag PD system (Balance; Fresenius Medical Care, St. Wendel, Germany). In an intention-to-treat analysis, patient and technique survival, peritonitis-free survival, and peritonitis rates were compared in 611 patients treated with Balance for up to 30 months and 551 patients with a standard PDF (stay . safe; Fresenius Medical Care) treated in the same era and with equivalent follow-up.


RESULTS
The patients were well matched for most relevant characteristics except older age distribution for the patients treated with the standard PDF. Patients treated with Balance had significantly superior survival compared to those treated with the standard PDF (74% vs 62% at 28 months, p = 0.0032). In a multivariate Cox regression model including age, diabetes, and gender, the survival advantage persisted (relative risk of death for Balance 0.75, 95% confidence interval 0.56 - 0.99, p = 0.0465). Modality technique survival was similarin Kaplan-Meieranalysis for both PDFs. No differences were detected in peritonitis-free survival or in peritonitis rates between the two solutions.


CONCLUSION
This study, for the first time, suggests that treatment with a novel biocompatible PDF with low GDP concentration and neutral pH confers a significant survival advantage. The exact mechanisms for such a survival advantage cannot be determined from this study. The usual criticisms of observational studies apply and the results reported here strongly warrant the undertaking of appropriately designed, randomized, controlled clinical trials.
18237995
mtDNAmanager: a Web-based tool for the management and quality analysis of mitochondrial DNA control-region sequences
BackgroundFor the past few years, scientific controversy has surrounded the large number of errors in forensic and literature mitochondrial DNA (mtDNA) data. However, recent research has shown that using mtDNA phylogeny and referring to known mtDNA haplotypes can be useful for checking the quality of sequence data.ResultsWe developed a Web-based bioinformatics resource "mtDNAmanager" that offers a convenient interface supporting the management and quality analysis of mtDNA sequence data. The mtDNAmanager performs computations on mtDNA control-region sequences to estimate the most-probable mtDNA haplogroups and retrieves similar sequences from a selected database. By the phased designation of the most-probable haplogroups (both expected and estimated haplogroups), mtDNAmanager enables users to systematically detect errors whilst allowing for confirmation of the presence of clear key diagnostic mutations and accompanying mutations. The query tools of mtDNAmanager also facilitate database screening with two options of "match" and "include the queried nucleotide polymorphism". In addition, mtDNAmanager provides Web interfaces for users to manage and analyse their own data in batch mode.ConclusionThe mtDNAmanager will provide systematic routines for mtDNA sequence data management and analysis via easily accessible Web interfaces, and thus should be very useful for population, medical and forensic studies that employ mtDNA analysis. mtDNAmanager can be accessed at http://mtmanager.yonsei.ac.kr.
21444564
FOXO3a turns the tumor necrosis factor receptor signaling towards apoptosis through reciprocal regulation of c-Jun N-terminal kinase and NF-kappaB.
OBJECTIVE
We evaluated the full range effects of FOXO3a in endothelial cells (ECs) by microarray analysis and investigated the role of FOXO3a regulating TNF receptor signaling pathway.


METHODS AND RESULTS
Human umbilical vein endothelial cells (HUVECs) were transfected with adenoviral vectors expressing constitutively active FOXO3a (Ad-TM-FOXO3a). Ad-TM-FOXO3a transfection caused remarkable apoptosis, which were accompanied with upregulation of genes related with TNF receptor signaling, such as TNF-alpha, TANK (TRAF-associated NF-kappaB activator), and TTRAP (TRAF and TNF receptor-associated protein). Furthermore, kappaB-Ras1 (IkappaB-interacting Ras-like protein-1) which is known to block IkappaB degradation was found increased, and intranuclear translocation of NF-kappaB was inhibited. GADD45beta and XIAP, negative regulators of c-Jun N-terminal kinase (JNK), were suppressed and JNK activity was increased. Attenuation of TNF signaling pathway either by blocking antibody for TNF receptor or by blocking JNK with DMAP (6-dimethylaminopurine) or Ad-TAM67 (dominant negative c-Jun) cotransfection, significantly reduced FOXO3a-induced apoptosis. Finally, treatment of vasculature with heat shock, an activator of endogenous FOXO3a, resulted in EC apoptosis, which was completely rescued by Ad-TAM67.


CONCLUSIONS
FOXO3a promotes apoptosis of ECs, through activation of JNK and suppression of NF-kappaB. These data identify a novel role of FOXO3a to turn TNF receptor signaling to a proapoptotic JNK-dependent pathway.