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The University Course Timetabling Problem (UCTP) is a scheduling problem of assigning teaching event in certain time and room by considering the constraints of university stakeholders such as students, lecturers, and departments. The constraints could be hard (encouraged to be satisfied) or soft (better to be fulfilled). This problem becomes complicated for universities which have an immense number of students and lecturers. Moreover, several universities are implementing student sectioning which is a problem of assigning students to classes of a subject while respecting individual student requests along with additional constraints. Such implementation enables students to choose a set of preference classes first then the system will create a timetable depend on their preferences. Subsequently, student sectioning significantly increases the problem complexity. As a result, the number of search spaces grows hugely multiplied by the expansion of students, other variables, and involvement of their constraints. However, current and generic solvers failed to meet scalability requirement for student sectioning UCTP. In this paper, we introduce the Multi-Depth Genetic Algorithm (MDGA) to solve student sectioning UCTP. MDGA uses the multiple stages of GA computation including multi-level mutation and multi-depth constraint consideration. Our research shows that MDGA could produce a feasible timetable for student sectioning problem and get better results than previous works and current UCTP solver. Furthermore, our experiment also shows that MDGA could compete with other UCTP solvers albeit not the best one for the ITC-2007 benchmark dataset.

Background: Type I interferons (IFN1s; eg, interferon-alpha and interferon-beta) are potent cytokines that inhibit the replication of human immunodeficiency virus-1 (HIV-1) and other viruses. The antiviral and immunoregulatory activities of IFN1 are mediated through ligand-receptor interactions with the IFN1 receptor complex (IFNAR). Variation in the cell-surface density of IFNAR could play a role in HIV-1 pathogenesis., Methods: In this cross-sectional study of fresh whole blood, we used flow cytometry to evaluate the expression of IFNAR2 on lymphocyte subsets from HIV-1-infected (n = 33) and HIV-1-uninfected (n = 22) individuals., Results: In comparison with healthy blood bank donors, we observed that the HIV-1-infected individuals, particularly those having advanced to disease, exhibited the increased expression of IFNAR2 on CD4 T cells (relative fluorescence intensity 6.9 vs. 9.0; P = 0.027). The CD4:CD4 T-cell IFNAR2 expression-level ratio provides an internally standardized measure of this alteration. The observed increased expression of IFNAR2 was largely restricted to CD4 T cells that expressed the chemokine receptor CXCR4 and lacked the expression of CCR5., Conclusions: HIV-1-infected individuals exhibit an increased expression of the IFN1 receptor on CD4 T cells. The level of IFNAR2 expression seems to increase with disease progression. These findings provide insight for the immunologic alterations associated with HIV-1 infection and possibly new therapeutic approaches.

In HIV-1 infection, plasmacytoid dendritic cell (PDC) numbers and function are decreased. No detailed comparisons of PDC responses to various stimuli in HIV-1-infected patients are available. Using for the first time purified PDCs, we compared PDC responses [interferon (IFN)-α production/cell] to various stimuli in a large number (n=48) of HIV-1-infected patients and healthy volunteers (n=19). Toll-like receptor (TLR)7- and TLR9-induced expression of PDC surface activation and maturation markers was also compared in the two populations. We have confirmed that PDC number coincides with CD4(+) T cell counts and clinical state. Notably, we have shown that a direct association of PDC function in terms of IFN-α production/cell exists with PDC numbers and CD4(+) cell counts when PDCs are exposed to a TLR9 ligand and HIV-infected cells, but not with a TLR7 ligand. Moreover, in the HIV-infected subjects but not the healthy controls, the magnitude of IFN-α release per PDC in response to the TLR7 ligand is significantly (p<0.01) lower than that to the TLR9 ligand. However, in both study populations, the TLR7 stimulation in comparison to TLR9 stimulation induced higher expression of PDC surface activation and maturation markers and significantly (p<0.05) decreased the expression of BDCA-2, a negative regulator of interferon. Furthermore, the cross-ligation of BDCA-2 significantly (p<0.05) inhibited TLR9- but not TLR7-induced IFN-α production by PDCs from both clinical groups. These findings suggest that differences exist in TLR7- and TLR9-induced IFN-α production by PDCs in HIV-infected individuals that are not directly related to BDCA-2 down-modulation.

Objectives: Reduced dendritic cell (DC) frequencies and functions in individuals with longstanding HIV-1 infection are predictive of opportunistic infections and AIDS. To investigate possible early alterations in DC levels after HIV infection, we prospectively examined plasmacytoid dendritic cell (pDC) and myeloid dendritic cell (mDC) frequencies and plasma IFN-alpha levels in patients undergoing primary HIV-1 infection (PHI)., Methods: Peripheral blood DC frequencies and absolute counts were determined by flow cytometry. Plasma IFN-alpha levels were measured by enzyme-linked immunosorbent assay (ELISA)., Results: In comparison to uninfected subjects, pDC, but not mDC, levels were reduced (P < 0.001) in subjects with PHI, especially in those with high viral loads or low CD4 T-cell counts. During 24-48 weeks of observation, untreated subjects experienced slight declines in pDC and CD4 T-cell levels. In contrast, subjects initiating early antiretroviral therapy (ART) exhibited increases (P < 0.001) in pDC and CD4 T-cell counts. No effect of treatment on mDC counts was observed. Circulating plasma IFN-alpha was undetectable by ELISA regardless of the duration of HIV-1 infection., Conclusion: PHI is characterized by a reduction in pDC and CD4 T-cell counts that correlates with the magnitude of virus replication and is not evidenced by the mDC count or plasma IFN-alpha level. Early ART appears to have similar restorative effects on pDC and CD4 T-cell counts.

Plasmacytoid and myeloid dendritic cells are reduced in AIDS patients. The number of these circulating cells was assessed cross-sectionally and longitudinally in 27 uninfected and 72 HIV-infected subjects on and off antiretroviral therapy. The plasmacytoid dendritic cell numbers were significantly reduced in the HIV-infected subjects compared to controls (p < 0.001). This reduction correlated directly with CD4+ cell counts (p < 0.001) and inversely with viral load (p < 0.001). These associations were found to a lesser degree for the myeloid dendritic cells. Intra-assay variability of these dendritic cell counts was < 10%. Antiretroviral therapy significantly increased plasmacytoid dendritic cell (p < 0.001) and CD4+ cell (p = 0.05) counts at 8 months by 76.9% and 19%, respectively. The plasmacytoid dendritic cell levels responded more readily to viral load increases and decreases than CD4+ cells. Circulating plasmacytoid dendritic cells may provide important additional information about immune function in HIV-infected subjects receiving or not receiving antiretroviral therapy.

Plasmacytoid dendritic cells (PDC), natural type-1 interferon (IFN) producing cells, could play a role in the innate anti-HIV immune response. Previous reports indicated that PDC IFN production is induced by HIV. Our results show a more robust IFN induction when purified PDC (>95%) were exposed to HIV-infected cells. This effect was not observed with non-viable cells, DNA, and RNA extracted from infected cells, and viral proteins. The response was blocked by anti-CD4 and neutralizing anti-gp120 antibodies as well as soluble CD4. IFN induction by HIV-infected cells was also prevented by low-dose chloroquine, which inhibits endosomal acidification. PDC IFN release resulted in reduced HIV production by infected CD4+ cells, supporting an anti-HIV activity of PDC. Stimulated CD4+ cells induced PDC activation and maturation; markers for PDC migration (CCR7) were enhanced by HIV-infected CD4+ cells only. This latter finding could explain the decline in circulating PDC in HIV-infected individuals.

CD8(+) cells activated in the presence of autologous macrophages (Mphi) have an increased ability to suppress HIV replication compared to the same cells stimulated in the absence of Mphi. Blocking the B7 molecules decreases the ability of Mphi to increase CD8(+) cell antiviral activity. In the present study CD8(+) cells exposed to purified forms of both the CD80 and the CD86 molecules during stimulation with anti-CD3 antibodies (Ab) had a greater ability to suppress HIV replication than CD8(+) cells exposed to anti-CD3 Ab alone. The addition of anti-CD86 blocking Ab, but not anti-CD80 blocking Ab, to Mphi decreased their ability to enhance CD8(+) cell suppression of HIV replication. Moreover, anti-CD86 Ab and not anti-CD80 Ab blocked the production of IL-2 by CD8(+) cells stimulated in the presence of Mphi. The incapacity of anti-CD80 Ab to block the enhanced antiviral activity and IL-2 production of CD8(+) cells stimulated in the presence of Mphi was not due to the inability of this Ab to function since anti-CD80 Ab are able to block proliferation of CD8(+) cells cultured in the presence of Mphi. Thus, while both B7 molecules can deliver a costimulatory signal sufficient to increase CD8(+) cell antiviral activity, CD86 appears to be the molecule that serves as the costimulatory molecule on Mphi to enhance CD8(+) cell suppression of HIV replication. The difference in use of CD86 over CD80 molecules on Mphi by CD8(+) cells mediating the antiviral suppressing activity most likely results from a higher number of Mphi expressing the CD86 molecule compared with the CD80 molecule. This information offers a possible therapeutic approach to increase CD8(+) cell anti-HIV response., (Copyright 1999 Academic Press.)

All human immunodeficiency virus (HIV) isolates can grow readily in primary CD4(+) T cells, but they can be distinguished by their ability to replicate in macrophages and established T-cell lines. The macrophage-tropic viruses are generally non-syncytium inducing (NSI), whereas the T-cell-line-tropic viruses are syncytium inducing (SI) in cultured cells. We now demonstrate that infection of CD4(+) T cells by NSI and SI viruses shows a differential effect on production of beta-chemokines and gamma interferon. Infection by NSI viruses increased production of MIP-1alpha, MIP-1beta, and gamma interferon, whereas infection by SI viruses had no effect or decreased production of these cytokines. Production of RANTES was slightly increased during infection by both virus phenotypes. This differential effect of NSI and SI viruses was observed at the level of beta-chemokine mRNA as well as at the level of protein expression. Infection by NSI viruses also increased CD4(+) cell proliferation. These results may have relevance for a differential role of HIV strains in AIDS pathogenesis.

Infection with the human immunodeficiency virus (HIV) leads to a decrease in CD4(+) T cells and disease progression within a decade of seroconversion. However, a small group of infected people, despite being infected by HIV for 10 or more years, remain clinically asymptomatic and have stable CD4(+) cell counts without taking antiretroviral medication. To determine why these individuals, known as long-term survivors (LTS), remain healthy, the hematological profiles, viral load and properties, HIV coreceptor genotype, and anti-HIV immune responses of these people were compared with those of individuals who have progressed to disease (Progressors) over the same time period. Unlike Progressors, LTS have a low circulating viral load and a low number of HIV-infected cells. These differences in the levels of the viral load were not associated with a dominant biologic viral phenotype, varying growth kinetics of the virus, mutation in the cellular CCR5 gene, or the presence of neutralizing antibodies. Importantly, the difference in viral load could be explained by the enhanced ability of CD8(+) cells from LTS to suppress HIV replication., (Copyright 1998 by The American Society of Hematology)

A subset of CD8+ T lymphocytes that expresses CD28, a membrane receptor for B7 differentiation Ags found on APCs, is primarily responsible for the noncytotoxic suppression of HIV replication in CD4+ cells of HIV-infected individuals. Optimal inhibition of HIV production by CD8+ cells occurs after triggering the CD28 molecule on the cells with anti-CD28 Abs during stimulation. Blocking the interaction of the CD28 and B7 molecules with a CTLA4Ig fusion protein abrogates the ability of autologous macrophages to enhance this CD8+ cell antiviral activity. This blocking effect can be reversed by treating the CD8+ cells with anti-CD28 Ab. The increase in antiviral activity following CD28 costimulation correlates with enhanced IL-2 production and IL-2R expression by CD8+ cells. Prevention of IL-2 binding to its receptor, using anti-IL-2 or anti-IL-2R Abs, reduces the ability of CD8+ cells to suppress HIV replication following CD28 costimulation. Importantly, engagement of the CD28 molecule during stimulation of CD8+ cells from individuals with AIDS restored the ability of their cells to suppress HIV replication. Thus, triggering the CD28 molecule during stimulation of CD8+ cells could clinically benefit HIV-infected symptomatic patients.