On a doubly reduced model for dynamics of heterogeneous mixtures of stiffened gases, its regularizations and their implementations.

We deal with the reduced four-equation model for the dynamics of heterogeneous compressible binary mixtures with the stiffened gas equations of state. We study its further reduced form, with the excluded volume concentrations, and with a quadratic equation for the common pressure of the components; this form can be called a quasi-homogeneous form. We prove new properties of the equation, derive simple formulas for the squared speed of sound, and present an alternative proof for a formula that relates it to the squared Wood speed of sound; also, a short derivation of the pressure balance equation is given. For the first time, we introduce regularizations of the heterogeneous model (in the quasi-homogeneous form). Previously, regularizations of such types were developed only for the homogeneous mixtures of perfect polytropic gases, and it was unclear how to cover the case considered here. In the 1D case, based on these regularizations, we construct new explicit two-level in time and symmetric three-point in space finite-difference schemes without limiters and provide numerical results for various flows with shock waves.

Tspan33 is Expressed in Transitional and Memory B Cells, but is not Responsible for High ADAM10 Expression.

Tetraspanins are a family of transmembrane proteins that form membrane microdomains. They play important roles in migration, adhesion and other cellular processes. TspanC8, a subfamily of tetraspanins, was found to associate and promote ADAM10 trafficking and cell surface localization. One of its members, Tspan33, is expressed in activated B cells. Using RT-PCR and flow cytometry, we analysed the pattern of expression of Tspan33 in B cells from healthy donors. We found Tspan33 expression in early and late stages of B cell development. However, Tspan33 expression did not correlate with ADAM10 surface expression. We also found expression of Tspan33 early in the activation process. Given its predominant expression in activated B cells and in several lymphomas, but not in naive B cells, we hypothesize that Tspan33 could be a potential target for therapeutic purposes.

Neutrophil functions in morbidly obese subjects.

The present study aimed to determine different peripheral blood neutrophil functions in 18 morbidly obese subjects with body mass index (BMI) ranging between 35 and 69 kg/m(2) in parallel with age- and gender-matched lean controls. Peripheral blood neutrophil functions of obese subjects and matched lean controls were determined. Neutrophils of obese subjects showed significant elevation of the release of basal superoxides (P < 0.0001), formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated superoxides (P < 0.0001) and opsonized zymosan (OZ)-stimulated superoxides (P < 0.045) compared with lean controls. Interestingly, there were no differences in phorbol myristate acetate (PMA)-stimulated superoxide production by neutrophils of the obese subjects and controls. There was also a significant elevation of chemotactic (P < 0.0003) and random (P < 0.0001) migration of neutrophils from obese subjects compared with lean controls. Phagocytosis, CD11b surface expression and adherence of neutrophils from obese subjects were not significantly different from those of the lean controls. The elevated superoxide production and chemotactic activity, together with the normal phagocytosis and adherence, suggest that neutrophils from obese subjects are primed and have the capability to combat infections. However, neutrophils in the priming state may participate in the pathogenesis of obesity-related diseases.

Allergic sensitization to pegylated interferon-α results in drug eruptions.

BACKGROUND: The introduction of pegylated interferon (PEG-IFN)-α in the treatment of chronic hepatitis C has led to an increase in sustained virological response. Despite reduced immunogenicity of the pegylated form in comparison with native interferon (IFN)-α, a high frequency of adverse cutaneous reactions has been reported with pegylated IFN-α. Here, we aimed to investigate the immunological mechanisms underlying pegylated IFN-α-induced drug eruptions. METHODS: Hepatitis C patients suffering from drug eruptions in association with administration of pegylated interferons were enrolled in the study (n = 22). Subjects were tested for sensitivity to pegylated IFN-α2a , pegylated IFN-α2b , or ribavirin using intradermal, scratch, and/or patch tests, as well as lymphocyte activation tests (LATs). Skin biopsies obtained from pegylated IFN-α-associated exanthemas, as well as from localized inflammatory skin reactions at pegylated IFN-α injection sites, were analyzed for the expression of relevant chemokines by quantitative real-time PCR and immunohistochemistry. RESULTS: A subset of patients suffering from pegylated IFN-α-associated exanthemas displayed positive intradermal tests to PEG-IFNs but not to conventional IFN (11/22). In selected patients, this observation correlated with the presence of pegylated IFN-specific T cells (3/11). Chemokine profiles of inflammatory skin reactions at the injection sites reflected an IFN-α-signature, whereas lesional skin of exanthemas showed induction of TH2-associated chemokines. CONCLUSIONS: Our results indicate that specific sensitizations are one cause of exanthemas under therapy with PEG-IFNs. Clinical proof-of-concept analyses demonstrate that affected patients may benefit from a switch to conventional, nonpegylated drugs, enabling IFN-α therapy continuation without drug-associated skin eruptions.

A comparison between amylase levels from peritonsillar, dental and neck abscesses.

OBJECTIVES: Pus of peritonsillar abscess (PTA) contains very high amylase levels in some patients. The objective of this study was to further test this finding and to check whether high amylase levels in peritonsillar abscess originate from contamination by saliva during aspiration. STUDY DESIGN: Prospective study. SETTING: Tertiary care university hospital. PARTICIPANTS: The study includes 64 patients with PTA, 8 patients with a neck abscess and 12 patients with a dental abscess. MAIN OUTCOME MEASURE: Amylase levels of pus and serum were compared between the groups. Clinical data regarding hospitalisation length, recurrence rate and previous antibiotic treatment were also collected. RESULTS: Mean amylase levels in the pus of the PTA group were 3045 U/L (median 59 U/L), 13 U/L in the neck abscess group (P = 0.001) and 22 U/L in the dental abscess group (P = 0.001). Mean serum amylase was higher in the PTA group; PTA - 50 U/L, neck abscess - 37 U/L (P = 0.002) and dental abscess - 26 U/L (P < 0.002). All of the patients with amylase levels above 65 U/L had a first episode of PTA. In contrast, 40% of patients with amylase lower than 65 U/L had recurrent PTA (P = 0.003). CONCLUSION: A clear association is seen between minor salivary glands and peritonsillar abscess. The high amylase level in peritonsillar pus is not from contamination with saliva.

Combined chemokine and cytokine gene transfer enhances antitumor immunity.

The probability of producing a specific antitumor response should be increased by multiplying the number of T lymphocytes that encounter the malignant cells. We tested this prediction in a murine model, using a recently discovered T-cell chemokine, lymphotactin (Lptn). This chemokine increased tumor cell infiltration with CD4+ lymphocytes but generated little antitumor activity. Coexpression of the T-cell growth factor interleukin-2, however, greatly expanded the T lymphocytes attracted by Lptn, affording protection from the growth of established tumor in a CD4+ and CD8+ T cell-dependent manner. Lesser synergy was seen with GM-CSF. Hence coexpression of a T-cell chemokine and T-cell growth factor potentiates antitumor responses in vivo, suggesting a general strategy to improve cancer immunotherapy.

Tumor necrosis factor alpha/cachectin is a growth factor for thymocytes. Synergistic interactions with other cytokines.

Recombinant murine (rm) TNF-alpha but not recombinant human (rh) TNF-alpha induces the proliferation of murine thymocytes in the presence of a comitogenic stimulus. This effect does not appear to be due to the production of significant levels of IL-1, IL-2, or IL-4. although not directly mitogenic (i.e., in the absence of PHA-P) for thymocytes, rmTNF-alpha amplifies the direct mitogenic signals from hIL-1 and rhIL-2 but not rmIL-4. In the presence of PHA-P, thymocytes stimulated with hIL-1, rhIL-2, and rmIL-4 produced significant amounts of TNF-alpha. Although rhTNF-alpha does not induce a proliferative response, it will competitively inhibit the proliferative response of thymocytes to rmTNF-alpha. These data suggest a critical role for TNF-alpha in the intrathymic proliferation of developing T cells.

The major histocompatibility complex-restricted antigen receptor on T cells. II. Role of the L3T4 product.

We have examined the role of the murine homologue of Leu-3 T4, L3T4, in recognition of antigen in association with products of the major histocompatibility complex (Ag/MHC) by murine T cell hybridomas. A series of ovalbumin (OVA)/I-Ad-specific T cell hybridomas were ranked in their sensitivity to Ag/I by measuring their ability to respond to low doses of OVA, or their sensitivity to inhibition by anti-I-Ad antibodies. T cell hybridomas with low apparent avidity for OVA/I-Ad, i.e. that did not respond well to low concentrations of OVA and were easily inhibited by anti-I-Ad, were also easily inhibited by anti-L3T4 antibodies. The reverse was true for T cell hybridomas with apparent high avidity for Ag/MHC. We found that the presence of low doses of anti-L3T4 antibodies caused T cell hybridomas to respond less well to low doses of Ag, and to be more easily inhibited by anti-I-Ad antibodies. These results suggested that the role of the L3T4 molecule is to increase the overall avidity of the reaction between T cells and Ag-presenting cells. In support of this idea was the discovery of several L3T4- subclones of one of our L3T4+ T cell hybridomas, D0.11.10. The L3T4- subclones had the same amount of receptor for OVA/I-Ad as their L3T4+ parent, as detected by an anti-receptor monoclonal antibody. The L3T4- subclones, however, responded less well to low doses of OVA, and were more easily inhibited by anti-I-Ad antibodies than their L3T4/ parent. These results showed that the L3T4 molecule was not required for surface expression of, or functional activity of, the T cell receptor for Ag/MHC. The L3T4 molecule did, however, increase the sensitivity with which the T cell reacted with Ag/MHC on Ag-presenting cells.

Interleukin-induced increase in Ia expression by normal mouse B cells.

The constitutive culture supernatant (SN) of the macrophage tumor line P388D1 (P388 SN) and the concanavalin A (Con A)-induced culture supernatant of the T cell hybridoma FS6-14.13 (FS6 Con A SN) were shown to contain nonspecific factors capable of inducing increased Ia expression by normal resting B cells in a dose-dependent manner. In six consecutive experiments the relative increase in Ia expression induced by P388 SN was 4.9 +/- 0.9, with FS6 Con A SN 10.7 +/- 1.5, and with a combination of both preparations 13.0 +/- 1.7. This increase in Ia expression was observed to occur in virtually all the B cells, reaching maximum levels within 24 h of culture. The interleukin-induced increase in B cell Ia expression occurred in the absence of ancillary signals provided by ligand-receptor Ig cross-linking and despite the fact that virtually all the control B cells, cultured in the absence of factors, remained in G0. These results suggest that functional receptors for at least some interleukins are expressed on normal resting B cells and their effects can be manifest in the absence of additional activating signals. The increased Ia expression induced by the nonspecific factor preparations was shown to be correlated with enhanced antigen-presenting capacity by the B cells to T cell hybridomas. The nature of the interleukins responsible for these effects remains to be definitively determined, however, the activity of FS6 Con A SN was shown to correlate with B cell growth factor activity and increased B cell Ia expression was not observed using interleukin 2 (IL-2) or interferon-gamma, prepared by recombinant DNA technology.

Generation of lytic natural killer 1.1+, Ly-49- cells from multipotential murine bone marrow progenitors in a stroma-free culture: definition of cytokine requirements and developmental intermediates.

We have developed a stroma-free culture system in which mouse marrow or thymus cells, known to be enriched for lymphoid progenitors, can be driven to generate natural killer (NK) cells. Culture of lineage marker (Lin)-, c-kit+, Sca2+, interleukin (IL)-2/15Rbeta (CD122)- marrow cells in IL-6, IL-7, stem cell factor (SCF), and flt3 ligand (flt3-L) for 5-6 d followed by IL-15 alone for an additional 4-5 d expanded the starting population 30-40-fold and gave rise to a virtually pure population of NK1.1+, CD3- cells. Preculture in IL-6, IL-7, SCF, and flt3-L was necessary for inducing IL-15 responsiveness in the progenitors because the cells failed to significantly expand when cultured in IL-15 alone from the outset. Although culture of the sorted progenitors in IL-6, IL-7, SCF, and flt3-L for the entire 9-11-d culture period caused significant expansion, no lytic NK1.1+ cells were generated if IL-15 was not added, demonstrating a critical role for IL-15 in NK differentiation. Thus, two distinct populations of NK progenitors, IL-15 unresponsive and IL-15 responsive, have been defined. Similar results were obtained with Lin-, CD44+, CD25-, c-kit+ lymphoid progenitors obtained from adult thymus. The NK cells generated by this protocol lysed the NK-sensitive target YAC-1 and expressed markers of mature NK cells with the notable absence of Ly-49 major histocompatibility complex (MHC) receptors. However, despite the apparent lack of these inhibitory MHC receptors, the NK cells generated could distinguish MHC class I+ from class I- syngeneic targets, suggesting the existence of novel class I receptors.

The reduced expression of 6Ckine in the plt mouse results from the deletion of one of two 6Ckine genes.

6Ckine is an unusual chemokine capable of attracting naive T lymphocytes in vitro. It has been recently reported that lack of 6Ckine expression in lymphoid organs is a prominent characteristic of mice homozygous for the paucity of lymph node T cell (plt) mutation. These mice show reduced numbers of T cells in lymph nodes, Peyer's patches, and the white pulp of the spleen. The genetic reason for the lack of 6Ckine expression in the plt mouse, however, has remained unknown. Here we demonstrate that mouse 6Ckine is encoded by two genes, one of which is expressed in lymphoid organs and is deleted in plt mice. A second 6Ckine gene is intact and expressed in the plt mouse.

Macrophage inflammatory protein 3alpha is expressed at inflamed epithelial surfaces and is the most potent chemokine known in attracting Langerhans cell precursors.

Dendritic cells (DCs) form a network comprising different populations that initiate and differentially regulate immune responses. Langerhans cells (LCs) represent a unique population of DCs colonizing epithelium, and we present here observations suggesting that macrophage inflammatory protein (MIP)-3alpha plays a central role in LC precursor recruitment into the epithelium during inflammation. (a) Among DC populations, MIP-3alpha was the most potent chemokine inducing the selective migration of in vitro-generated CD34(+) hematopoietic progenitor cell-derived LC precursors and skin LCs in accordance with the restricted MIP-3alpha receptor (CC chemokine receptor 6) expression to these cells. (b) MIP-3alpha was mainly produced by epithelial cells, and the migration of LC precursors induced by the supernatant of activated skin keratinocytes was completely blocked with an antibody against MIP-3alpha. (c) In vivo, MIP-3alpha was selectively produced at sites of inflammation as illustrated in tonsils and lesional psoriatic skin where MIP-3alpha upregulation appeared associated with an increase in LC turnover. (d) Finally, the secretion of MIP-3alpha was strongly upregulated by cells of epithelial origin after inflammatory stimuli (interleukin 1beta plus tumor necrosis factor alpha) or T cell signals. Results of this study suggest a major role of MIP-3alpha in epithelial colonization by LCs under inflammatory conditions and immune disorders, and might open new ways to control epithelial immunity.

CCR6, a CC chemokine receptor that interacts with macrophage inflammatory protein 3alpha and is highly expressed in human dendritic cells.

Dendritic cells initiate immune responses by ferrying antigen from the tissues to the lymphoid organs for presentation to lymphocytes. Little is known about the molecular mechanisms underlying this migratory behavior. We have identified a chemokine receptor which appears to be selectively expressed in human dendritic cells derived from CD34+ cord blood precursors, but not in dendritic cells derived from peripheral blood monocytes. When stably expressed as a recombinant protein in a variety of host cell backgrounds, the receptor shows a strong interaction with only one chemokine among 25 tested: the recently reported CC chemokine macrophage inflammatory protein 3alpha. Thus, we have designated this receptor as the CC chemokine receptor 6. The cloning and characterization of a dendritic cell CC chemokine receptor suggests a role for chemokines in the control of the migration of dendritic cells and the regulation of dendritic cell function in immunity and infection.

Selective recruitment of immature and mature dendritic cells by distinct chemokines expressed in different anatomic sites.

DCs (dendritic cells) function as sentinels of the immune system. They traffic from the blood to the tissues where, while immature, they capture antigens. They then leave the tissues and move to the draining lymphoid organs where, converted into mature DC, they prime naive T cells. This suggestive link between DC traffic pattern and functions led us to investigate the chemokine responsiveness of DCs during their development and maturation. DCs were differentiated either from CD34(+) hematopoietic progenitor cells (HPCs) cultured with granulocyte/macrophage colony-stimulating factor (GM-CSF) plus tumor necrosis factor (TNF)-alpha or from monocytes cultured with GM-CSF plus interleukin 4. Immature DCs derived from CD34(+) HPCs migrate most vigorously in response to macrophage inflammatory protein (MIP)-3alpha, but also to MIP-1alpha and RANTES (regulated on activation, normal T cell expressed and secreted). Upon maturation, induced by either TNF-alpha, lipopolysaccharide, or CD40L, DCs lose their response to these three chemokines when they acquire a sustained responsiveness to a single other chemokine, MIP-3beta. CC chemokine receptor (CCR)6 and CCR7 are the only known receptors for MIP-3alpha and MIP-3beta, respectively. The observation that CCR6 mRNA expression decreases progressively as DCs mature, whereas CCR7 mRNA expression is sharply upregulated, provides a likely explanation for the changes in chemokine responsiveness. Similarly, MIP-3beta responsiveness and CCR7 expression are induced upon maturation of monocyte- derived DCs. Furthermore, the chemotactic response to MIP-3beta is also acquired by CD11c+ DCs isolated from blood after spontaneous maturation. Finally, detection by in situ hybridization of MIP-3alpha mRNA only within inflamed epithelial crypts of tonsils, and of MIP-3beta mRNA specifically in T cell-rich areas, suggests a role for MIP-3alpha/CCR6 in recruitment of immature DCs at site of injury and for MIP-3beta/CCR7 in accumulation of antigen-loaded mature DCs in T cell-rich areas.

Aberrant in vivo T helper type 2 cell response and impaired eosinophil recruitment in CC chemokine receptor 8 knockout mice.

Chemokine receptors transduce signals important for the function and trafficking of leukocytes. Recently, it has been shown that CC chemokine receptor (CCR)8 is selectively expressed by Th2 subsets, but its functional relevance is unclear. To address the biological role of CCR8, we generated CCR8 deficient (-/-) mice. Here we report defective T helper type 2 (Th2) immune responses in vivo in CCR8(-/)- mice in models of Schistosoma mansoni soluble egg antigen (SEA)-induced granuloma formation as well as ovalbumin (OVA)- and cockroach antigen (CRA)-induced allergic airway inflammation. In these mice, the response to SEA, OVA, and CRA showed impaired Th2 cytokine production that was associated with aberrant type 2 inflammation displaying a 50 to 80% reduction in eosinophils. In contrast, a prototypical Th1 immune response, elicited by Mycobacteria bovis purified protein derivative (PPD) was unaffected by CCR8 deficiency. Mechanistic analyses indicated that Th2 cells developed normally and that the reduction in eosinophil recruitment was likely due to systemic reduction in interleukin 5. These results indicate an important role for CCR8 in Th2 functional responses in vivo.

Homeostasis of glutamate in brain fluids: an accelerated brain-to-blood efflux of excess glutamate is produced by blood glutamate scavenging and offers protection from neuropathologies.

L-Glutamate (Glu) homeostasis in brain extracellular fluids and its maintenance at low micromolar concentrations in the face of the extremely high Glu concentrations present in brain cells and synaptic vesicles have been commonly attributed to the very effective action of glutamate transporters present on neuronal and glial cells. This view however does not take into account the fact that the brain is highly vascularized and that the vasculature harbors a high density of glutamate transporters. In this article, we review the accumulated data establishing the existence of an efflux of excess Glu from brain extracellular fluids into blood. We describe plausible mechanisms accounting for this efflux and present evidence that the brain-to-blood Glu efflux is modulated by blood Glu levels and can be accelerated by blood Glu scavenging. The latter procedure shown here to afford brain neuroprotection in a rat model of closed head injury could be applicable, as a first-line therapy, in the various acute brain insults characterized by excess Glu in brain fluids.

6-C-kine (SLC), a lymphocyte adhesion-triggering chemokine expressed by high endothelium, is an agonist for the MIP-3beta receptor CCR7.

The beta chemokine known as 6-C-kine, secondary lymphoid-tissue chemokine (SLC), TCA4, or Exodus-2 (herein referred to as 6CK/SLC) can trigger rapid integrin-dependent arrest of lymphocytes rolling under physiological shear and is highly expressed by high endothelial venules, specialized vessels involved in lymphocyte homing from the blood into lymph nodes and Peyer's patches. We show that 6CK/SLC is an agonist for the lymphocyte chemoattractant receptor, CCR7 (EBI-1, BLR-2), previously described as a receptor for the related beta chemokine MIP-3beta (ELC or Exodus-3). Moreover, 6CK/SLC and MIP-3beta attract the same major populations of circulating lymphocytes, including naive and memory T cells > B cells (but not natural killer cells); desensitization to MIP-3beta inhibits lymphocyte chemotaxis to 6CK/SLC but not to the alpha chemokine SDF-1 (stromal cell-derived factor); and 6CK/SLC competes for MIP-3beta binding to resting mouse lymphocytes. The findings suggest that the majority of circulating lymphocytes respond to 6CK/SLC and MIP-3beta in large part through their common receptor CCR7 and that these molecules may be important mediators of physiological lymphocyte recirculation in vivo.

Chemokines and the arrest of lymphocytes rolling under flow conditions.

Circulating lymphocytes are recruited from the blood to the tissue by rolling along the endothelium until being stopped by a signaling event linked to the Gialpha subunit of a heterotrimeric GTP-binding protein; that event then triggers rapid integrin-dependent adhesion. Four chemokines are now shown to induce such adhesion to intercellular adhesion molecule-1 and to induce arrest of rolling cells within 1 second under flow conditions similar to those of blood. SDF-1 (also called PBSF), 6-C-kine (also called Exodus-2), and MIP-3beta (also called ELC or Exodus-3) induced adhesion of most circulating lymphocytes, including most CD4+ T cells; and MIP-3alpha (also called LARC or Exodus-1) triggered adhesion of memory, but not naïve, CD4+ T cells. Thus, chemokines can regulate the arrest of lymphocyte subsets under flowing conditions, which may allow them to control lymphocyte-endothelial cell recognition and lymphocyte recruitment in vivo.

Gene array analysis comparison between rat collagen-induced arthritis and human rheumatoid arthritis.

Collagen-induced arthritis (CIA) is an experimental arthritis model used to study the inflammatory processes in this disease and test potential therapeutics. In order to better characterize this model, we conducted the first comprehensive gene expression analysis of rat CIA. To evaluate how closely the rat model reflects human rheumatoid arthritis (RA), we also analysed gene expression in human RA, using genome-wide Affymetrix gene arrays. By applying multiple strategies, including comparison of the highest induced genes, expression of immunological-associated genes as well as Ingenuity Pathway Analysis (IPA), we were able to compare the two expression profiles. Among the highest induced genes in RA were several B-cell-associated genes, including immunoglobulins, B-cell markers such as CD20, and cytokines and chemokines that act on B cells such as TNFSF13b/BLyS and CXCL13, none of which was upregulated in CIA. The latter was instead characterized by the upregulation of genes expressed primarily in macrophages and dendritic cells. Of the 22 pathways identified as significant in both diseases by IPA, only three (IL6, chemokine signalling and antigen presentation) were present in both settings. We conclude that there are significant differences in the inflammatory mechanisms between human RA and rat CIA, and that genome-wide comparative gene expression analyses are useful tools to evaluate the relevance of animal models to human disease.

T-cell subsets: chemokine receptors guide the way.

Recent results show that chemokine receptors and adhesion molecules can be differentially expressed on the different subsets of T helper cells, suggesting that regulated networks of gene expression may control tissue-specific migration of T helper cells.