Optimization of biomathematical model predictions for cognitive performance impairment in individuals: accounting for unknown traits and uncertain states in homeostatic and circadian processes

Current biomathematical models of fatigue and performance do not accurately predict cognitive performance for individuals with a priori unknown degrees of trait vulnerability to sleep loss, do not predict performance reliably when initial conditions are uncertain, and do not yield statistically valid estimates of prediction accuracy. These limitations diminish their usefulness for predicting the performance of individuals in operational environments. To overcome these 3 limitations, a novel modeling approach was developed, based on the expansion of a statistical technique called Bayesian forecasting. The expanded Bayesian forecasting procedure was implemented in the two-process model of sleep regulation, which has been used to predict performance on the basis of the combination of a sleep homeostatic process and a circadian process. Employing the two-process model with the Bayesian forecasting procedure to predict performance for individual subjects in the face of unknown traits and uncertain states entailed subject-specific optimization of 3 trait parameters (homeostatic build-up rate, circadian amplitude, and basal performance level) and 2 initial state parameters (initial homeostatic state and circadian phase angle). Prior information about the distribution of the trait parameters in the population at large was extracted from psychomotor vigilance test (PVT) performance measurements in 10 subjects who had participated in a laboratory experiment with 88 h of total sleep deprivation. The PVT performance data of 3 additional subjects in this experiment were set aside beforehand for use in prospective computer simulations. The simulations involved updating the subject-specific model parameters every time the next performance measurement became available, and then predicting performance 24 h ahead. Comparison of the predictions to the subjects' actual data revealed that as more data became available for the individuals at hand, the performance predictions became increasingly more accurate and had progressively smaller 95% confidence intervals, as the model parameters converged efficiently to those that best characterized each individual. Even when more challenging simulations were run (mimicking a change in the initial homeostatic state; simulating the data to be sparse), the predictions were still considerably more accurate than would have been achieved by the two-process model alone. Although the work described here is still limited to periods of consolidated wakefulness with stable circadian rhythms, the results obtained thus far indicate that the Bayesian forecasting procedure can successfully overcome some of the major outstanding challenges for biomathematical prediction of cognitive performance in operational settings.     

Establishment and characterization of two distinct malignant mesothelioma cell lines with common clonal origin

We describe two newly established malignant mesothelioma (MM) cell lines derived from a pleural effusion of a male. One cell line, designated as MM-Z03E, reveals an epithelioid cobblestone morphology, while the second one, designated as MM-Z03S and subcloned after in vivo selection, exhibits a sarcomatoid storiform growth pattern. Both cell lines showed the immunologic profile characteristic for MM (i.e., expression of cytokeratin, CK18, calretinin, and vimentin in both phenotypes). Cytogenetics, multicolor fluorescence in situ hybridization, comparative genomic hybridization, and oligonucleotide array CGH were performed on both cell lines. Aberrations shared by both cell lines included chromosomal losses of 1q34 approximately qter, 4, 9p, 10p, 13, 14, 16q, 18, and 22, as well as a complex structural aberration involving chromosome 17. Aberrations exclusive to MM-Z03E included gains of 3q11q27 and 5p, while gain of 9q and losses of 3q27qter, 11q, and 18 in MM-Z03S were exclusive to MM-Z03E. Both cell lines were able to develop solid transplant tumors in nude mice within 16 weeks, and immunophenotyping of tumor xenografts revealed an overall retained expression profile of the markers used. Remarkably, one xenograft from MM-Z03E revealed overexpression of p53 and widely invasive growth. In conclusion, both cell lines are useful in vivo and in vitro model systems to study the underlying genetic mechanisms of biphasic differentiation in MM, which can be of certain value considering the increasing relevance of assessing MM tumor biology for the clinical management of this disease.     

Dichotomous effects of C-C chemokines in HIV-1 pathogenesis

Whilst many physiological functions of nitric oxide (NO) have been revealed so far, recent evidence proposes an essential role for NO in T lymphocyte activation and signal transduction. NO acts as a second messenger, activating soluble guanyl cyclase and participating in signal transduction pathways involving cyclic GMP. NO modulates mitochondrial events that are involved in apoptosis and regulates mitochondrial biogenesis in many cell types, including lymphocytes. Several studies undertaken on patients with RA and SLE have documented increased endogenous NO synthesis, although the effects of NO may be distinct. Here, we discuss recent evidence that NO contributes to T cell dysfunction in both SLE and RA by altering multiple signaling pathways in T cells. Although NO may play a physiological role in lymphocyte cell signaling, its overproduction may perturb T cell activation, differentiation and effector responses, each of which may contribute in different ways to the pathogenesis of autoimmunity.     

A point mutation in the putative ATP binding site of the pseudorabies virus US3 protein kinase prevents Bad phosphorylation and cell survival following apoptosis induction

The multifunctional US3 protein kinase is conserved among alphaherpesviruses. Like the herpes simplex virus US3 protein kinase, the pseudorabies virus (PRV) US3 protein confers resistance against apoptosis. In the current report, we introduced a point mutation in the putative ATP binding site of the PRV US3 protein kinase. We found that, in contrast to the wild type PRV US3, the point-mutated PRV US3 does not protect cells from apoptosis induced by PRV infection or staurosporine treatment. In addition, we found that the presence of wild type PRV US3, but not of the point-mutated PRV US3, results in phosphorylation of the pro-apoptotic Bad protein in PRV-infected ST and HEp-2 cells. In PRV-infected ST cells, but not in HEp-2 cells, an additional, US3- and phosphorylation-independent alteration of Bad could be observed. These results suggest that the kinase activity of the US3 protein of PRV is crucial to protect cells from apoptotic cell death during infection, at least partly by leading to phosphorylation of the pro-apoptotic Bad protein.     

Exposure to a farming environment has allergen-specific protective effects on TH2-dependent isotype switching in response to common inhalants

BACKGROUND: IgE synthesis by human B cells results from allergen-dependent, T(H)2-mediated isotype switching. Exposure to a farming environment protects against IgE responses. OBJECTIVE: We reconstructed allergen-dependent switching patterns in vivo to identify the level or levels at which farm exposure acts to protect against atopy. METHODS: Serum IgG1 to IgG4 and IgE to grass (rPhl p 1 and rPhl p 5), cat (rFel d 1), and mite (rDer p 2) were assessed by means of ELISA in the Allergy and Endotoxin study population (812 children). Farm exposure was defined as currently living on a farm, exposure to stables/farm milk in the first year of life, or both. RESULTS: Farm exposure did not affect allergen-specific IgG2 and IgG3 levels but had complex allergen-specific effects on IgG1, IgG4, and IgE levels. Exposure protected against grass-specific responses at every step along the IgG1/IgG4/IgE switching pathway but had no significant effect on mite responses. Protection from cat responses was concentrated at the IgG1 level. For all allergens, failure to express IgG1 was associated with low prevalence of IgG4 or IgE responses. Notably, coexpression of IgG1, IgG4, and IgE to grass was associated with increased risk of allergic disease and higher IgE levels compared with production of IgG1 and IgE without IgG4, suggesting IgG4 coexpression marks stronger activation of T(H)2-dependent events. CONCLUSION: The protective effects of farm exposure were confined to T(H)2-dependent IgG1, IgG4, and IgE expression and were allergen and switch stage specific, suggesting that distinct mechanisms regulate individual steps within allergen-induced class switching in vivo. CLINICAL IMPLICATIONS: Environmental interventions to prevent IgE expression might need to be tailored to specific allergens.     

Skin inflammation in RelB(-/-) mice leads to defective immunity and impaired clearance of vaccinia virus

BACKGROUND: Atopic dermatitis (AD) is an inflammatory skin disorder occurring in genetically predisposed individuals with a systemic T(H)2 bias. Atopic dermatitis patients exposed to the smallpox vaccine, vaccinia virus (VV), occasionally develop eczema vaccinatum (EV), an overwhelming and potentially lethal systemic infection with VV. OBJECTIVE: To establish a murine model of EV and examine the effects of skin inflammation on VV immunity. METHODS: The skin of RelB(-/-) mice, like that of chronic AD lesions in humans, exhibits thickening, eosinophilic infiltration, hyperkeratosis, and acanthosis. RelB(-/-) and wild-type (WT) control mice were infected with VV via skin scarification. Viral spread, cytokine levels, IgG2a responses and VV-specific T cells were measured. RESULTS: Cutaneously VV-infected RelB(-/-), but not WT mice, exhibited weight loss, markedly impaired systemic clearance of the virus and increased contiguous propagation from the inoculation site. This was associated with a dramatically impaired generation of IFN-gamma-producing CD8(+) vaccinia-specific T cells along with decreased secretion of IFN-gamma by VV-stimulated splenocytes. The T(H)2 cytokines-IL-4, IL-5, IL-13, and IL-10-on the other hand, were overproduced. When infected intraperitoneally, RelB(-/-) mice generated robust T cell responses with good IFN-gamma production. CONCLUSION: Allergic inflammation in RelB(-/-) mice is associated with dysregulated immunity to VV encountered via the skin. We speculate that susceptibility of AD patients to overwhelming vaccinia virus infection is similarly related to ineffective T cell responses. CLINICAL IMPLICATIONS: The susceptibility of patients with AD to EV following cutaneous contact with VV is related to ineffective antiviral immune responses.     

Molecular discrimination of atypical bovine spongiform encephalopathy strains from a geographical region spanning a wide area in Europe

Transmissible spongiform encephalopathy strains can be differentiated by their behavior in bioassays and by molecular analyses of the disease-associated prion protein (PrP) in a posttranslationally transformed conformation (PrPSc). Until recently, isolates from cases of bovine spongiform encephalopathy (BSE) appeared to be very homogeneous. However, a limited number of atypical BSE isolates have recently been identified upon analyses of the disease-associated proteinase K (PK) resistance-associated moiety of PrPSc (PrPres), suggesting the existence of at least two additional BSE PrPres variants. These are defined here as the H type and the L type, according to the higher and lower positions of the nonglycosylated PrPres band in Western blots, respectively, compared to the position of the band in classical BSE (C-type) isolates. These molecular PrPres variants, which originated from six different European countries, were investigated together. In addition to the migration properties and glycosylation profiles (glycoprofiles), the H- and L-type isolates exhibited enhanced PK sensitivities at pH 8 compared to those of the C-type isolates. Moreover, H-type BSE isolates exhibited differences in the binding of antibodies specific for N- and more C-terminal PrP regions and principally contained two aglycosylated PrPres moieties which can both be glycosylated and which is thus indicative of the existence of two PrPres populations or intermediate cleavage sites. These properties appear to be consistent within each BSE type and independent of the geographical origin, suggesting the existence of different BSE strains in cattle. The choice of three antibodies and the application of two pHs during the digestion of brain homogenates provide practical and diverse tools for the discriminative detection of these three molecular BSE types and might assist with the recognition of other variants.     

Exosomal vaccines containing the S protein of the SARS coronavirus induce high levels of neutralizing antibodies

Infection with the SARS-associated coronavirus (SARS-CoV) induces an atypical pulmonary disease with a high lethality rate. Although the initial SARS epidemic was contained, sporadic outbreaks of the disease still occur, suggesting a continuous need for a vaccine against this virus. We therefore explored exosome-based vaccines containing the spike S proteins of SARS-CoV. S-containing exosomes were obtained by replacing the transmembrane and cytoplasmic domains of the S protein by those of VSV-G. The immunogenicity and efficacy of the S-containing exosomes were tested in mice and compared to an adenoviral vector vaccine expressing the S protein. Both, S-containing exosomes and the adenoviral vector vaccine induced neutralizing antibody titers. After priming with the SARS-S exosomal vaccine and boosting with the adenoviral vector the neutralizing antibody titers exceeded those observed in the convalescent serum of a SARS patient. Both approaches were effective in a SARS-S-expressing tumor challenge model and thus warrant further investigation.