bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐dose long wave visible light induces perinuclear vacuolization in vivo but does not result in early photoageing and apoptosis
Authors: Tjioe Milan , Smits Tim , Blokx Willeke A. M. , Van De Kerkhof Peter C. M. , Gerritsen Marie‐Jeanne P.
Published: September 2003

Abstract:  With the advancing widespread use of photodynamic therapy, questions have arisen about the necessity to protect the adjacent healthy skin from high‐dose long‐wave light. The aim of the present study was to investigate the effects of high dose visible light on the skin of healthy volunteers with focus on apoptosis, DNA damage, inflammation, melanogenesis and induction of matrix metalloproteinases (MMP). Fourteen healthy volunteers were included and irradiated daily on their buttocks with 1300 kJ/m2 long wave visible light (560–780 nm) on five consecutive days with a cumulative dose of 6500 kJ/m2. In each volunteer six biopsies were taken before and 24 h after irradiation on days 1, 2, 3 and 5 and on day 8 and 12. Frozen and paraffin sections were investigated by measuring parameters for photodamage (apoptosis, p53, phosphorylated c‐Jun), skin ageing (phosphorylated c‐Jun, MMP‐1, elastin content) melanogenesis (Melan A). Although no sunburn cells were seen, a significant increase in perinuclear vacuolization was noted (P < 0.0003) from day 5 till 7 days after the last irradiation. There was no expression of phosphorylated c‐Jun, whereas the expression of p53, Melan A, MMP‐1 and elastin content did not change. High‐dose visible light induces a significant increase in perinuclear vacuolization, but does not result in apoptosis, photodamage or early induction of skin ageing.
Effect of the lactic acid bacterium Streptococcus thermophilus on stratum corneum ceramide levels and signs and symptoms of atopic dermatitis patients
Authors: Di Marzio Luisa , Centi Carla , Cinque Benedetta , Masci Silvio , Giuliani Maurizio , Arcieri Anna , Zicari Luigi , De Simone Claudio , Cifone Maria Grazia
Published: September 2003

Abstract:  A reduced amount of total ceramides could be responsible for functional abnormalities of the skin of atopic dermatitis (AD) patients. The ability of an experimental cream containing sonicated Streptococcus thermophilus to increase skin ceramide levels in healthy subjects has been previously reported. The aim of the present work was to investigate the effects of the topical administration of a S. thermophilus‐containing cream on ceramide levels of stratum corneum from AD patients. A 2‐week application of the cream, containing a sonicated preparation of the lactic acid bacterium S. thermophilus, in the forearm skin of 11 patients led to a significant and relevant increase of skin ceramide amounts, which could have resulted from the sphingomyelin hydrolysis through the bacterial sphingomyelinase. Moreover, in all patients the topical application of our experimental cream also resulted in the improvement of the signs and symptoms characteristic of AD skin (i.e. erythema, scaling, pruritus).
Novel and recurrent mutations in the integrin beta 4 subunit gene causing lethal junctional epidermolysis bullosa with pyloric atresia
Authors: Iacovacci S. , Cicuzza S. , Odorisio T. , Silvestri E. , Kayserili H. , Zambruno G. , Puddu P. , D'Alessio M.
Published: September 2003

Abstract:  In this study we examined two unrelated patients affected with the lethal variant of junctional epidermolysis bullosa with pyloric atresia (PA‐JEB) who were found to carry mutations in the integrin β4 subunit gene (ITGB4). Although in both patients Northern blot analysis showed only a 50% reduction in the level of ITGB4 transcript, a complete lack (patient 1) or a strong reduction (patient 2) of β4 immunoreactivity was observed in the skin. Using immunoprecipitation analysis, integrin β4 could not be visualized in patient 1 cells while a markedly reduced amount (∼20%) of normal sized β4 chains was detected in patient 2. These data suggested the presence of ITGB4 mutations that interfere with both mRNA and protein stability. Using molecular analysis, patient 1 was shown to be a compound heterozygous for a single amino acid deletion (ΔN318) and a not yet identified mutation that induces a very rapid decay of the encoded mRNA transcript. Patient 2 was, instead, a compound heterozygous for a novel 4‐bp tandem duplication (4298–4299ins4) and a previously described missense mutation (R252C). Our data support the notion that PA‐JEB lethal phenotypes associated with a markedly decreased/absent α6β4 expression can be due not only to the presence of null alleles, but also to specific mutations leading to protein instability and/or altered function.
Comparison of two in vitro dendritic cell maturation models for screening contact sensitizers using a panel of methacrylates
Authors: Rustemeyer T. , Preuss M. , Von Blomberg B. M. E. , Das P. K. , Scheper R. J.
Published: September 2003

Abstract: Allergen‐induced emigration and maturation of dendritic cells (DC) are pivotal steps in sparking off allergic contact dermatitis. In vitro models, reflecting these steps, may provide tools for assessment of sensitizing capacities of putative contact allergens. Here, we evaluated the applicability of such models for a panel of methacrylate congeners, the sensitizing properties of which were established previously in clinical and experimental animal studies. First, using interleukin‐4 (IL‐4)/granulocyte–macrophage colony‐stimulating factor (GM‐CSF)‐induced, blood monocyte‐derived DC, hapten‐induced up‐regulation of maturation/activation markers, including CD80, CD83, CD86, chemokine receptors CXCR4 and CCR5, as well as the drug resistance related molecules P‐glycoprotein (Pgp) and lung resistance protein (LRP), were monitored by flow cytometry. Of note, whereas CD86 and CXCR4 were most sensitive in discriminating between the contact sensitizers and irritants included in the panel, i.e. sodium dodecyl sulphate (SDS) and croton oil (CO), assessment of CD83 and LRP expression reflected the relatively lower sensitizing capacity of methyl methacrylate. Second, using ex vivo skin explant cultures, allergen‐induced LC migration from epidermal to basal membranous and dermal skin structures was most reliably monitored by CD1a, as compared with Pgp, LRP, HLA‐DR or CD54 staining. The extent of CD1a+ LC migration was found to closely correlate with the sensitizing capacities of the panel of test compounds. These results support the view that both in vitro models can provide valuable data on contact sensitizing properties, and add chemokine receptors and drug resistance related molecules to the list of DC membrane markers revealing allergenic signaling.
CD4 is expressed by epidermal Langerhans' cells predominantly as covalent dimers
Authors: Lynch G. W. , Slaytor E. K. , Elliott F. D. , Saurajen A. , Turville S. G. , Sloane A. J. , Cameron P. U. , Cunningham A. L. , Halliday G. M.
Published: September 2003

Abstract:  Langerhans' cells (LC) of skin are CD4 expressing, dendritic, antigen‐presenting cells, that are essential for activation of primary immune responses and are productively infected by HIV. We have shown previously that lymphocytes and monocytes express CD4 both as monomers and covalently linked homodimers. In those cells the 55‐kDa monomer structure predominates. LC in un‐fractionated human epidermal cell (EC) suspension also expresses both forms of CD4, but in EC the dimer form is predominant. Because isolation of LC into single cell suspension by trypsin, as is routinely used for LC isolation, degrades CD4, a systematic study for an alternate procedure for LC isolation was performed. Thus it was found that collagenase blend F treatment can efficiently release LC into suspension, under conditions of only minimal degradation of control soluble recombinant CD4 or CEM‐T4 or THP‐1 cell CD4, or importantly of LC surface CD4. SDS–PAGE immunoblotting of purified LC extracted from EC by collagenase confirmed CD4 structure as predominantly 110‐kDa dimers, with only minimal 55‐kDa monomers. The suitability of LC prepared thus for functional studies was demonstrated with binding of functional ligand HIV gp120. It remains to be determined, however, why tissue embedded LC express mainly CD4 dimers, but single‐celled blood lymphocytes and monocytes mainly monomers.
The tolerogenic molecule CD95‐L is expressed on the plasma membrane of human activated, but not resting, Langerhans' cells.
Authors: De Panfilis G. , Venturini M. , Lavazza A. , Mommaas M. A. , Semenza D. , Torresani C. , Pasolini G.
Published: September 2003

Abstract:  Although dendritic cells (DC) are well known for their immunogenic capacities, they may even induce peripheral T‐cell tolerance, and such a tolerogenic potential can be exerted in mouse through the expression on the DC plasma membrane of the CD95‐ligand (CD95‐L) molecule, which is able to trigger apoptosis of CD95‐expressing antigen‐specific T cells. We therefore asked whether epidermal DC, namely Langerhans' cells (LC), either resting (i.e. within the epidermis, ‘in situ’) or activated (i.e. suspended from the epidermis) or both, could express the CD95‐L molecule on the plasma membrane. For such a purpose, two colloidal gold‐immunoelectron microscopy (IEM) double‐step procedures were carried out: an ‘in situ’ method, able to investigate resting LC, was performed on ultrathin frozen sections obtained by ultracryomicrotomy (UCMT) of normal skin biopsies; a pre‐embedding (P‐E) method, able to investigate suspended LC, was performed on epidermal cells (EC) suspended from normal skin specimens. In UCMT/IEM sections, resting LC showed gold particles within the cytoplasm but very rarely within organelles and never along the plasma membrane: resting LC are therefore capable of synthesizing CD95‐L but not of expressing it in a functional location, thus autoreactive phenomena against CD95‐expressing EC being avoided in normal epidermis. On the other hand, in P‐E/IEM preparations, suspended LC showed several gold particles along the plasma membrane: activated LC are therefore capable of expressing CD95‐L in a functional location, thus bearing the potential to exert tolerogenic capabilities against CD95‐expressing T cells, e.g. to prevent inflammatory/autoimmune cutaneous disorders and/or favor the resolution thereof.
Regulation of PDGF and PDGF receptor in cultured dermal papilla cells and follicular keratinocytes of the human hair follicle
Authors: Kamp H. , Geilen C. C. , Sommer C. , Blume‐Peytavi U.
Published: September 2003

Abstract:  Platelet‐derived growth factor (PDGF) is a potent mitogenic factor for many cell types and has been shown to be important in follicular development and vasculogenesis. In this study, we examined the expression pattern of both PDGF factors and their corresponding receptors in mesenchyme‐derived dermal papilla cells (DPCs) and epithelial follicular keratinocytes (FKs). Both types of PDGF receptors are expressed in FKs, whereas DPCs only express PDGF receptor β on the protein level, a finding also seen in whole organ cultures. By examining the expression of PDGF ligands, we were able to show that cultured FKs synthesize both PDGF‐A and PDGF‐B, whereas, DPCs only express PDGF‐A.

As immunomodulatory cytokines were shown to affect hair growth, we investigated the effects of IL‐1β, IL‐4, TNF‐α, TGF‐β and IFN‐γ on the expression levels of PDGF factors in cultured DPCs and FKs. Interestingly, we could show a significant down‐regulatory effect by catagen‐inducing cytokines like IL‐1β or IFN‐γ, suggesting a possible involvement of PDGF signaling in the induction of catagen. The question concerning the latter hypothesis remains to be elucidated in further studies on whole organ cultures.
Differential effects of UV irradiation on nuclear retinoid receptor levels in cultured keratinocytes and melanocytes
Authors: Andersson Eva , Rosdahl Inger , Törmä Hans , Vahlquist Anders
Published: September 2003

Abstract:  A major risk factor for skin cancer is UV irradiation, which not only damages DNA and other photosensitive compounds like vitamin A, but may also perturb cellular signaling, e.g. via the retinoid receptor system believed to be important for cancer protection. We used cultured normal human keratinocytes and melanocytes to examine the effects of UV irradiation on the expression of the predominant retinoid receptors in the human skin (RARα, RARγ and RXRα) and the AP‐1 protein c‐Jun; mRNA levels were studied by real‐time PCR and protein levels by Western blot. In keratinocytes, a single dose of UVB (50 mJ/cm2) caused a rapid drop in the expression of all three receptors (mRNA levels minus 35–50% after 4 h; protein levels minus 20–45% after 8 h), which was followed over the next 40 h by a variable response, leading to full normalization for RARα only. In contrast, the levels of c‐Jun did not change significantly after UV exposure. In melanocytes, UVB caused a similar drop of the retinoid receptor levels as in keratinocytes but this was soon followed by an increased expression leading to a complete normalization of all receptor levels within 1–3 days. The c‐Jun levels in melanocytes increased 1 day after UV exposure and remained high (plus 50%) thereafter. In both cell types, a ∼3‐fold increase in apoptosis (measured by DNA fragmentation) was observed 8–48 h after UVB irradiation. In conclusion, a depletion of vitamin A and retinoid receptors by UV irradiation, together with unchanged or even increased c‐Jun levels, might seriously interfere with retinoid signaling and thus promote future tumor development, especially in keratinocytes.
Naïve CD4+ T cells from patients with atopic dermatitis show an aberrant maturation towards IL‐4‐producing skin‐homing CLA+ cells
Authors: Jung T. , Moessner R. , Neumann C.
Published: September 2003

Abstract:  Overproduction of interleukin‐4 (IL‐4) has been reported in lesional and in peripheral T cells from patients with atopic dermatitis (AD). It is not clear whether the development of IL‐4‐producing T helper type 2 (Th2) cells from naïve precursors is an intrinsic phenomenon of T cells or whether other, extrinsic factors play a significant role. To analyze these alternatives, we investigated the IL‐4 production of effector T cells generated in vitro from highly purified CD4+ CD45RA+ naïve T cells in the absence of signals derived from antigen‐presenting cells. Effector T cells generated from naïve precursors from both AD and healthy donors produced comparable amounts of IL‐4 after restimulation. Priming in the presence of exogenous IL‐4 enhanced the production of IL‐4 while neutralizing endogenously produced IL‐4 abolished IL‐4 production similarly in atopic and healthy T cells. A subset of effector T cells acquired the expression of the cutaneous lymphocyte antigen (CLA). The frequency of CLA+ T cells was not different between atopic and healthy donors. CLA+ T cells, differentiated from naïve atopic, but not healthy T cells, showed a preferential Th2 cytokine profile as assessed by intracellular cytokine staining. Also effector T cells derived from atopic patients without dermatitis tended to show this imbalance, although it was not significantly different to healthy controls. This Th2 cytokine profile did not develop when naïve T cells were cultured in the presence of IL‐12. In conclusion, high IL‐4 production in developing T cells from AD patients was associated with CLA expression, the net IL‐4 production of all effector CD4+ T cells, however, was similar to IL‐4 production by T cells from healthy donors.
230‐kDa and 190‐kDa proteins in addition to desmoglein 1 as immunological targets in a subset of pemphigus foliaceus with a combined cell‐surface and basement membrane zone immune staining pattern
Authors: Karlhofer F. M. , Hashimoto T. , Slupetzky K. , Kiss M. , Liu Y. , Amagai M. , Pieczkowski F. , Foedinger D. , Kirnbauer R. , Stingl G.
Published: September 2003

Abstract:  Pemphigus erythematosus, initially described as a combination of pemphigus with lupus erythematosus, and pemphigus foliaceus are now frequently considered localized and generalized variants of superficial pemphigus. Yet diagnostic criteria for pemphigus erythematosus remain controversial. Distinct from pemphigus foliaceus, pemphigus erythematosus displays immune depositions at the dermal‐epidermal junction, which suggests additional immunopathological mechanisms. We present three patients with clinical and histopathologic signs of superficial pemphigus, who all exhibited an immunomorphology characteristic of pemphigus erythematosus. Complement depositions in a granular‐linear fashion were consistently found at the dermal‐epidermal junction besides in vivo bound and circulating antikeratinocyte cell‐surface autoantibodies. Histopathology showed subcorneal acantholysis, and all sera contained antidesmoglein 1 but not antidesmoglein 3 autoantibodies detected by enzyme‐linked immunosorbent assays (ELISA). Additional autoantibodies against a 230‐kDa protein and against a 190‐kDa protein comigrating with bullous pemphigoid antigen 1 (BP230) and periplakin, respectively, were present in all the patients' sera. As two sera specifically reacted with BP230 by ELISA, the presence of BP230‐specific autoantibodies could be associated with dermal‐epidermal immune staining in these patients. In pemphigus erythematosus, dermal–epidermal immune staining is generally attributed to the deposition of immune complexes, while the presence of BP230‐specific autoantibodies has not been reported in this disease previously. Perhaps, the unique autoantibody profile of the patients in the study permits discrimination between patients with superficial pemphigus that display additional dermal‐epidermal immune staining from those with conventional pemphigus foliaceus on a molecular basis. Further studies will be required to substantiate the frequency of this occurrence and to unravel its pathogenic significance.
Organogenesis of peripheral lymphoid organs
Authors: Nishikawa Shin‐Ichi , Honda Kenya , Vieira Paul , Yoshida Hisahiro
Published: September 2003

Summary:  The discovery that lymphotoxin α (LTα) knockout mice lack peripheral lymphoid tissues reformed the study of organogenesis of peripheral lymphoid tissues from a research field that was solely descriptive and dependent on histological methods to one requiring all modern technologies. The concepts of inducer cells for organogenesis of peripheral lymphoid tissues as a separate hematopoietic lineage and of mesenchymal organizer cells have been established through this progress. These discoveries led to the comprehension of the basic framework of the events during organogenesis of peripheral lymphoid tissues. However, many important questions remain unanswered. This review discusses those questions which have arisen from our studies on the organogenesis of Peyer's patches.
Regulation of secondary lymphoid organ development by the nuclear factor‐κB signal transduction pathway
Authors: Weih Falk , Caamaño Jorge
Published: September 2003

Summary:  In primary lymphoid organs, such as thymus and bone marrow, B and T lymphocytes differentiate from lymphoid stem cells into mature albeit naïve effector cells. In contrast, secondary lymphoid organs, such as the spleen, lymph nodes, and Peyer's patches (PPs), provide an environment that enable lymphocytes to interact with each other, with accessory cells, and with antigens, resulting in the initiation of antigen‐specific primary immune responses. Recently, the analysis of gene‐knockout mice has shed light on the signaling pathways, cellular requirements, and molecular mechanisms involved in secondary lymphoid organ development. In particular, signals that converge on the nuclear factor‐κB (NF‐κB) pathway have been demonstrated to play an important role in both early developmental steps as well as maintenance of secondary lymphoid organ structures. Analysis of the histopathological changes in secondary lymphoid tissues of mice lacking individual Rel/NF‐κB family members, upstream kinases, and receptors strongly indicates that activation of the recently described alternative NF‐κB pathway by membrane‐bound lymphotoxin, via p52–RelB heterodimers, plays a major role during initiation steps of secondary lymphoid organ development. Induction of the classical p50–RelA NF‐κB activity, as exemplified by tumor necrosis factor receptor signaling, clearly also contributes, but seems to be involved primarily in later developmental step, such as the proper cellular and structural organization of B‐cell follicles.
Lymphoid microenvironment in the gut for immunoglobulin A and inflammation
Authors: Chin Robert , Wang Jing , Fu Yang‐Xin
Published: September 2003

Summary:  Signaling through lymphotoxin β receptor (LTβR) initiates the unfolding of a host of developmental programs ranging from the organogenesis of lymph nodes and Peyer's patches (PPs) to the coordination of splenic microarchitecture. While investigating an alternative pathway to immunoglobulin A (IgA) production, it was uncovered that LTβR signaling in the lamina propria (LP) stroma orchestrates the coordinated expression of key chemokines and adhesion molecules, creation of a cytokine milieu, and stroma development that facilitates robust IgA production independent of secondary lymphoid structures. Simultaneously, this same infrastructure can be commandeered by autoreactive T cells to organize both the acute destruction of the intestinal mucosa and chronic intestinal inflammation via the ligands for LTβR. The ability to modulate LTβR signaling may alternatively permit the suppression of autoimmune responses and augmentation of gut defenses.
Chemokines in the systemic organization of immunity
Authors: Campbell Daniel J. , Kim Chang H. , Butcher Eugene C.
Published: September 2003

Summary:  Directed cellular migrations underlie immune system organization. Chemokines and their receptors (along with surface‐adhesion molecules) are central to these migrations, targeting developing and mature leukocytes to tissues and microenvironments suitable for their differentiation and function. The chemokine CXCL12 and its receptor CXCR4 play a central role in the migration of hematopoietic stem cells, and several chemokine receptors are transiently expressed during distinct stages of B‐ and T‐cell development. In the periphery, mature naïve B and T cells utilize the receptors CCR7, CXCR4, and CXCR5 to recirculate through specialized microenvironments within the secondary lymphoid tissues, while effector and memory lymphocytes express bewildering patterns of adhesion molecules and chemokine receptors that allow them to function within microenvironments and non‐lymphoid tissues inaccessible to naïve cells. Here, we summarize the role of chemokines and their receptors in the spatial organization of the immune system and consider the implications for immune function.
Egress: a receptor‐regulated step in lymphocyte trafficking
Authors: Rosen Hugh , Sanna Germana , Alfonso Christopher
Published: September 2003

Summary:  Blood lymphocyte numbers, which are maintained by recirculation through secondary lymphoid organs, are essential for the efficient development of immune responses. Recirculating populations of B and T lymphocytes are regulated by the sphingosine‐1‐phosphate (S1P) receptor‐dependent control of lymphocyte egress. T‐cell egress from thymus into blood, egress from lymph node and Peyer's patch into lymph, and B‐cell egress into lymph are rapidly and completely inhibited by agonism of S1P receptors. Mesenteric lymph nodes show log‐jamming of lymphocytes subjacent to sinus‐lining endothelium. Agonism of S1P receptors produces rapid peripheral blood lymphopenia, which is maintained in the presence of receptor agonist. Effector CD4+ and CD8+ T cells, produced by clonal expansion in draining lymph node in response to antigen, are sequestered in lymph node and fail to reach the peripheral blood. The S1P receptor system may represent an early physiological link between the non‐specific inflammatory response and the alteration of lymphocyte traffic through draining lymph nodes. Pharmacological subversion of the S1P receptor system, through systemic S1P agonist‐induced inhibition of lymphocyte egress, suppresses antigenic responses to peripheral, but not to systemically, delivered antigen. This inhibition induces significant immunosuppression in models of transplantation and autoimmune tissue damage that may prove to be of clinical benefit.
Visualizing thymocyte motility using 2‐photon microscopy
Authors: Robey Ellen A. , Bousso Philippe
Published: September 2003

Summary:  Our view of a thymocyte based on its behavior in tissue culture and appearance in fixed tissue sections was of a round sessile cell. Its travel through the thymus might occur slowly, perhaps even passively, leaving it in contact with the support cells that happened to be in its immediate environment. However, when we got our first look at the behavior of thymocytes in a 3D cellular stromal cell environment, that picture changed dramatically. Instead we found that thymocytes are actively crawling, allowing them to explore their environment over relatively long distances and interact with peptide‐major histocompatibility complex (pMHC)‐bearing thymic stromal cells in both dynamic and stable modes. In this review, we discuss the implications of thymocyte motility for T‐cell repertoire selection and for the mechanisms that determine the spatial organization of thymocyte subsets within the thymus.
Genetic dissection of thymus development in mouse and zebrafish
Authors: Boehm Thomas , Bleul Conrad C. , Schorpp Michael
Published: September 2003

Summary:  Lymphoid organs represent a specialized microenvironment for interaction of stromal and lymphoid cells. In primary lymphoid organs, these interactions are required to establish a self‐tolerant repertoire of lymphocytes. While detailed information is available about the genes that control lymphocyte differentiation, little is known about the genes that direct the establishment and differentiation of principal components of such microenvironments. Here, we discuss genetic studies addressing the role of thymic epithelial cells (TECs) during thymopoiesis. We have identifed an evolutionarily conserved key regulator of TEC differentiation, Foxn1, that is required for the immigration of prothymocytes into the thymic primordium. Because Foxn1 specifies the prospective endodermal domain that gives rise to thymic epithelial cells, it can be used to identify the evolutionary origins of this specialized cell type. In the course of these studies, we have found that early steps of thymus development in zebrafish are very similar to those in mice. Subsequently, we have used chemical mutagenesis to derive zebrafish lines with aberrant thymus development. Strengths and weaknesses of mouse and zebrafish models are largely complementary such that genetic analysis of mouse and zebrafish mutants may lead to a better understanding of thymus development.
Dissecting the role of lymphotoxin in lymphoid organs by conditional targeting
Authors: Tumanov Alexei V. , Grivennikov Sergei I. , Shakhov Alexander N. , Rybtsov Stanislav A. , Koroleva Ekaterina P. , Takeda Junji , Nedospasov Sergei A. , Kuprash Dmitry V.
Published: September 2003

Summary:  Mice with inactivation of lymphotoxin β receptor (LTβR) system have profound defects in the development and maintenance of peripheral lymphoid organs. As surface LT is expressed by lymphocytes, natural killer cells, and lymphoid tissue‐initiating cells as well as by some other cell types, we dissected cell type‐specific LT contribution into the complex LT‐deficient phenotype by conditional gene targeting. B‐LTβ knockout (KO) mice displayed an intermediate phenotype in spleen as compared with mice with complete LTβ deficiency. In contrast, T‐LTβ KO mice displayed normal structure of the spleen. However, inactivation of LTβ in both T and B cells resulted in additional defects in the structure of the marginal zone and in the development of follicular dendritic cells in spleen. Structure of lymph nodes (LN) and Peyer's patches (PP) was normal in both B‐LTβ KO and T‐ and B‐LTβ KO mice, except that PPs were of reduced size. When compared across the panel of lymphocyte‐specific LT KOs, the defects in antibody responses to T‐cell‐dependent antigens correlated with the severity of defects in spleen structure. Expression of CCL21 and CCL19 chemokines was not affected in spleen, LN and PP of B‐LTβ KO and T‐ and B‐LTβ KO mice, while CXCL13 was slightly reduced only in spleen. Collectively, our data suggest the following: (i) requirements for LT signaling to support architecture of spleen, LN and PP are different; (ii) LT complex expressed by B cells plays a major role in the maintenance of spleen structure, while surface LT expressed by T cells provides a complementary but distinct signal; and (iii) in a non‐transgenic model, expression of lymphoid tissue chemokines is only minimally dependent on the expression of surface LT complex on B and T lymphocytes.
Structure, lymphatic vascularization and lymphocyte migration in mucosa‐associated lymphoid tissue
Authors: Azzali Giacomo
Published: September 2003

Summary:  In this review, we consider the morphological aspects and topographical arrangement of gut‐associated lymphoid tissue (GALT) (solitary and aggregate lymph nodules or Peyer's patches) and of vermiform appendix in the human child and in some mammals. The spatial arrangement of the vessels belonging to apparatus lymphaticus periphericus absorbens (ALPA) and of blood vessels within each lymphoid follicle as well as the ultrastructural characteristics of the lymphatic endothelium with high absorption capacity are considered. Particular attention is also paid to the morphological and biomolecular mechanisms inducing lymphocyte transendothelial migration to the bloodstream by means of lymphatic vessels as well as their passage from blood into lymphoid tissue through the high endothelial venules (HEVs). The preferential transendothelial passage of lymphocytes and polymorphonuclear neutrophils within ALPA vessels of the interfollicular area does not occur following the opening of intercellular contacts, but rather it occurs by means of ‘intraendothelial channels’. In HEVs, on the contrary, the hypothesis is plausible that lymphocyte transendothelial migration into lymphoid tissue occurs through a channel‐shaped endothelial invagination entirely independent of interendothelial contacts. The lymph of ALPA vessels of the single Peyer's patch is conveyed into precollector lymphatic vessels and into prelymph nodal collectors, totally independent of the ALPA vessels of the gut segments devoid of lymphoid tissue. The quantitative distribution of T lymphocytes in the lymph of mucosal ALPA vessels suggests a prevalent function of fluid uptake, whereas a reservoir and supply function is implicated for the vessels of interfollicular area. The precollector lymphatic vessels and prelymph nodal collectors are considered to be vessels with low absorption capacity, whose main function is lymph conduction and flow.
The impact of CCR7 and CXCR5 on lymphoid organ development and systemic immunity
Authors: Müller Gerd , Höpken Uta E. , Lipp Martin
Published: September 2003

Summary:  The development of secondary lymphoid organs is a complex process dependent on a coordinated interaction of cells of hematopoietic and non‐hematopoietic origin. In this context, chemokines and cytokines belonging to the tumor necrosis factor (TNF)/lymphotoxin (LT) family are critical signaling molecules during the initial steps of lymph node and Peyer's patch organogenesis. Homeostatic chemokines, such as CXCL13, CCL21, and CCL19, as well as their corresponding receptors, CXCR5 and CCR7, have now been shown to closely cooperate in the development of lymphoid organs and the maintenance of lymphoid tissue microarchitecture. We summarize recent data on the function of CXCR5 and CCR7 and their intricate connection to the TNF/LT system in order to refine the current model of lymphoid organ development.
The role of the nuclear hormone receptor RORγt in the development of lymph nodes and Peyer's patches
Authors: Eberl Gerard , Littman Dan R.
Published: September 2003

Summary:  The nuclear hormone receptor retinoic acid‐related orphan receptor (ROR)γt is required for the development of lymph nodes (LNs) and Peyer's patches (PPs), as these organs are absent in RORγt‐deficient mice. During fetal life, RORγt is expressed exclusively in lymphoid tissue‐inducer (LTi) cells, a cell type that localizes in developing LNs and PPs. LTi cells express surface lymphotoxin α1β2 that activates specialized mesenchymal cells to produce chemokines, upregulate adhesion molecules and induce further maturation of lymphoid organs. RORγt inhibits nuclear factor of activated T‐cell (NFAT) function in cell lines and induces the expression of Bcl‐xL and p27kip1 in the adult thymus, suggesting that RORγt prevents cell activation, cell‐cycle progression, and apoptosis. We propose that RORγt, together with the inhibitor of basic helix‐loop‐helix transcription factor Id2, ensures generation and survival of fetal LTi cells necessary for the development of LNs and PPs.
Lymphoid organ development and cell migration
Authors: Cyster Jason G.
Published: September 2003

Summary:  As we travel into a new century, confronted with new infectious diseases and bioweapon threats, with surgeons continuing to push the boundaries of what is transplantable, and with gene therapists working on ways to remedy a myriad of genetic diseases, the need for improved methods to augment and suppress immune function is paramount. The recent discovery that a novel immunosuppressant works by blocking lymphocyte egress from lymphoid organs provides a compelling example of how improved understanding of lymphoid organ function will contribute to future drug development and human health. This volume brings together reviews from leaders in the field of thymus and secondary lymphoid organ biology, including discussions on the roles of transcriptional regulators Foxn1, retinoid‐related orphan receptor γ and nuclear factor‐κB in lymphoid organ development, the function of lymphotoxin and other cytokines in lymphoid tissue organization, the guidance activity of chemokines in a multitude of immune cell‐positioning events, the mechanism of action of the immunosuppressant FTY720, and the application of two‐photon laser scanning microscopy to reveal the dynamic behavior of lymphoid cells in the depths of these essential tissues.
A stochastic view of lymphocyte motility and trafficking within the lymph node
Authors: Wei Sindy H. , Parker Ian , Miller Mark J. , Cahalan Michael D.
Published: September 2003

Summary:  Two‐photon microscopy is providing literal insight into the cellular dynamics of lymphoid organs and, guided by analysis of three‐dimensional images, into mechanisms that underlie cell migration and antigen recognition in vivo. This review describes lymphocyte motility and antigen recognition in the native tissue environment and compares these results with a much more extensive literature on lymphocyte motility, signaling, and chemotaxis in vitro. We discuss the in vitro literature on dynamic aspects of lymphocyte motility, chemotaxis, and the response to antigen and present the view that random migration of lymphocytes may drive a stochastic mechanism of antigen recognition in lymphoid organs, rather than being guided by chemotaxis.
Thymic generation and regeneration
Authors: Gill Jason , Malin Mark , Sutherland Jayne , Gray Daniel , Hollander George , Boyd Richard
Published: September 2003

Summary:  The thymus is a complex epithelial organ in which thymocyte development is dependent upon the sequential contribution of morphologically and phenotypically distinct stromal cell compartments. It is these microenvironments that provide the unique combination of cellular interactions, cytokines, and chemokines to induce thymocyte precursors to undergo a differentiation program that leads to the generation of functional T cells. Despite the indispensable role of thymic epithelium in the generation of T cells, the mediators of this process and the differentiation pathway undertaken by the primordial thymic epithelial cells are not well defined. There is a lack of lineage‐specific cell‐surface‐associated markers, which are needed to characterize putative thymic epithelial stem cell populations. This review explores the role of thymic stromal cells in T‐cell development and thymic organogenesis, as well as the molecular signals that contribute to the growth and expansion of primordial thymic epithelial cells. It highlights recent advances in these areas, which have allowed for a lineage relationship amongst thymic epithelial cell subsets to be proposed. While many fundamental questions remain to be addressed, collectively these works have broadened our understanding of how the thymic epithelium becomes specialized in the ability to support thymocyte differentiation. They should also facilitate the development of novel, rationally based therapeutic strategies for the regeneration and manipulation of thymic function in the treatment of many clinical conditions in which defective T cells have an important etiological role.
Temperature and heat transfer measurement in continuous reheating furnaces
Authors: Honner Milan , Vesely Zdenek , Svantner Michal
Published: September 2003

The paper deals with the measurement in continuous industrial furnaces. Measuring technique and measuring device are presented. Temperature evolutions are measured on the experimental billet and records of the furnace heating‐control system are shown. Furnace distributions of temperature, heat flux, and heat transfer coefficient are determined by means of the billet heating process computer modeling.
Thermodynamic investigation of Co–Cr alloys. II. Heat capacity measurements in the temperature interval 318–1660 K
Authors: Sterneland Thérèse , Aune Ragnhild E. , Seetharaman Seshadri
Published: September 2003

The thermodynamic properties of several Co–Cr alloys have been determined in the temperature interval 318–1660 K using differential scanning calorimetric (DSC) technique. The compositional range of the alloys investigated extended from 10 to 90 wt% Cr. Heat capacity equations, Cp (J/mol K) =A+B·T (K), were derived in the temperature interval of interest to fit the experimental data. The experimental Cp values are compared with those from the Neumann–Kopp rule. The phase transformations observed in the present measurements are discussed in the light of the phase diagram information available in the literature for the Co–Cr binary system.
Replacement of lead baths for the tempering of spring wire
Authors: Jarl Magnus , Berntsson Thomas , Sapcanin Edin , Azizi Basid
Published: September 2003

Molten lead is used for tempering of valve‐spring wire. Lead has drawbacks due to slow temperature changes. In 1991 the Swedish Parliament passed a Government Bill, in which proposals were made to phase out the use of lead in the long term, primarily through voluntary measures. Tempering of SIS 2090 (SAE 9254, DIN 55SiCr7) wire with different dimensions using induction heating was tested in a pilot process line. An induction coil for six wires and two coils with different lengths designed for single wires were tested. The results showed that an induction coil for six wires gave excessive temperature and property variations between the wires. The shorter of the single wire coils gave fluctuations in temperature and properties using a 3.00‐mm wire. No such fluctuations were observed with the longer coil. One of the experiments showed that the process might need time to reach stable conditions. The results so far indicate that it is possible to produce valve‐spring wire with induction tempering. The process needs more control and monitoring compared to tempering in molten lead.
Effects of ferrosilicon particle size on reduction rate of chromium oxide in slag
Authors: Lee Sang‐Beom , Song Hyoseok , Hwang Ho‐Yong , Rhee Peter Chang‐Hee , Klevan Ole‐Svein
Published: September 2003

For a successful stainless steelmaking process, it is necessary to reduce Cr oxide in slag, using ferrosilicon alloy, as quickly as possible. The effects of particle size on the melting rate of ferrosilicon alloy were investigated by monitoring melting behavior of ferrosilicon alloys both on stainless steel melt and on the slag using a video camera. The reduction experiment using an induction furnace of 50‐kg capacity was also carried out. The experimental results indicated that the smaller the particle size, the shorter the melting time, and it is shorter on steel melt than on slag. It was found that the reduction rate is controlled by the melting rate at the initial stage of reaction, but after the initial stage, the transfer of chromium oxide controls the overall rate.
The production of Al–Ti–B grain refining master alloys
Authors: Lee M. S. , Grieveson P.
Published: September 2003

In this paper the interfacial phenomena observed when an Al–Ti–B master alloy is produced are studied using a modified sessile drop technique. The effect of emulsification is demonstrated and the influence of small levels of CaF2 and MgF2 are seen. Al–Ti–B master alloys are made by the addition of potassium fluotitanate, K2TiF6, and potassium fluoborate, KBF4, to molten aluminium at 750°C. The product is an Al–5 wt% Ti–1 wt% B master alloy and a KF–AlF3 flux of eutectic composition. Problems can occur with the production of such alloys by (a) the emulsification of the liquid Al–Ti–B alloy and KF–AlF3 flux and (b) the agglomeration of titanium diboride particles by the wetting and engulfment of the KF–AlF3 flux. It has been found that levels of CaF2 and MgF2 in the fluoride salts greater than 50 ppm and 70 ppm, respectively, can prevent this emulsification and boride agglomeration.
Kinetics of reduction of FeO–Fe2MoO4–MoO2 mixtures toward the production of Fe–Mo alloys
Authors: Morales Ricardo
Published: September 2003

The kinetics of reduction of thin powder beds of oxide mixtures by hydrogen was investigated using a thermogravimetric technique. Four oxide mixtures with different Fe/Mo ratios were investigated. The experiments were carried out isothermally in the temperature range 873–1023 K. The reductant gas flow rate was kept at 0.5 l/min, which was above the starvation rate for the reaction. Thin beds of the oxide powders with particle sizes in the micron range were used. Under these conditions, the chemical reaction rate is expected to control the reduction processes. It was found that the reduction reaction consisted of two steps. The activation energies were calculated for every reduction step involved and the values are compared. XRD analyses of the obtained alloys showed two‐phase compositions, namely FexMoy and Fe or Mo. SEM analyses show the formation of bigger Fe particles surrounded by extremely fine Fe–Mo intermetallic phase, indicating thereby that FeO gets reduced in the first step to metallic iron and undergoes grain growth while the iron molybdate complex oxide gets reduced in the second step.
Experimental study of viscosities of selected CaO–MgO–Al2O3–SiO2 slags and application of the Iida model
Authors: Forsbacka Lasse , Holappa Lauri , Iida Takamichi , Kita Yoshifumi , Toda Yunie
Published: September 2003

Viscosities of quaternary CaO–MgO–Al2O3–SiO2 melts have been measured by rotating cylinder method up to a temperature of 1750°C. 8 slag compositions have been selected in the composition range 1.8–19.6 wt% CaO, 17.8–38.4 wt% MgO, 24.6–31.5 wt% Al2O3 and 25.6–41.2 wt% SiO2. An application of Iida's viscosity model has been made. The Iida model gave good consistency with the measured viscosity values.
Oscillatory flow in the steelmaking vessel
Authors: Lee M. S. , O'Rourke S. L. , Molloy N. A.
Published: September 2003

Physical modelling of the basic oxygen furnace (BOF) was undertaken with the object of developing an overall flow pattern within the vessel as a function of fluid‐flow dynamics/vessel geometry interaction. The study was initiated as the result of localised refractory wear occurring in the knuckle region of a BOF vessel. The occurrence of the wear coincided with a change in lance tip design. This preferential wear limited the campaign life of the vessel. Modelling the fluid dynamics of the system was to examine any possible relationship between fluid‐flow patterns and this refractory wear pattern. The 4‐fold symmetry of the newer lance tip allowed the application of a quadrant sector model of the bath. This simplified the flow to the effect of an individual nozzle. A scale of 1/6th was chosen on the basis of the bath depth and flow rates required. Results from this work indicate that waves may have a role in this localised wear.

The multiphase system of the BOF involving supersonic gas jets, molten iron and slag, and the interaction between these, ensure that there is no single model, in which all facets of similarity may be satisfied simultaneously. This is the major problem in modelling the BOF.
Neural adhesion molecule (N‐CAM) in pleomorphic adenoma and carcinoma ex‐pleomorphic adenoma
Authors: Saleh E. R. M. , França C. M. , Marques M. M.
Published: September 2003

Background:  The neural cell adhesion molecule (N‐CAM) has been implicated in the behaviour of the adenoid cystic carcinoma. In vitro, it was demonstrated that N‐CAM inhibits cell invasion. The aim of this study was to search for N‐CAM in the most common salivary gland tumour that has a malignant counterpart.

Methods:  We investigated the presence of N‐CAM in pleomorphic adenoma and its malignant counterpart, the carcinoma ex‐pleomorphic adenoma, using the immunohistochemistry technique.

Results:  Neural cell adhesion molecule was expressed in all cases of pleomorphic adenoma, strongly labelling the luminal cells of the double‐layered ductform structures. This expression was weaker in neoplastic myoepithelial cells and progressively diminished at a distance from the luminal cells. In carcinoma, ex‐pleomorphic adenoma N‐CAM was either totally absent or faintly present at the apical pole of the few luminal cells.

Conclusions:  As a result of the peculiar distribution of N‐CAM in pleomorphic adenoma, we speculated that N‐CAM behaves as a tumour‐suppressor molecule, which is expressed in the benign neoplasm and which is down‐regulated after malignancy, when the tumour assumes an invasive behaviour.
Immunohistochemical study of syndecan‐1 down‐regulation and the expression of p53 protein or Ki‐67 antigen in oral leukoplakia with or without epithelial dysplasia
Authors: Kurokawa Hideo , Matsumoto Shinobu , Murata Tomoyuki , Yamashita Yoshihiro , Tomoyose Taiki , Zhang Min , Fukuyama Hiroshi , Takahashi Tetsu
Published: September 2003

Background:  Leukoplakia is an oral pre‐cancerous lesion that sometimes develops into squamous cell carcinoma. Therefore, leukoplakia with epithelial dysplasia is useful for studying carcinogenesis at the cellular level. The purpose of this study was to evaluate a potential association between the loss of syndecan‐1 expression and the expression of p53 protein and Ki‐67 antigen, and to identify reliable markers for predicting malignant changes in oral leukoplakia with epithelial dysplasia.

Methods:  Changes in the expression of syndecan‐1, p53, and Ki‐67 were examined immunohistochemically in 43 cases of oral leukoplakia with or without epithelial dysplasia. The subjects were categorized as: none, 13 cases; mild dysplasia, 5 cases; moderate dysplasia, 17 cases; and severe dysplasia, 8 cases. The expression of these molecules in normal oral epithelia (22 cases) was also investigated.

Results:  Strong syndecan‐1 expression was observed on the surface of keratinocytes in normal epithelium. Immunopositivity was lost gradually as the extent of epithelial dysplasia increased. In normal epithelium, p53 and Ki‐67 appeared mainly in the basal cell layer, while they were more widely distributed in leukoplakia. Specifically, significant changes were observed in the labeling index of p53 and Ki‐67 in leukoplakia as epithelial dysplasia progressed from mild to moderate or severe.

Conclusion:  Our results reveal that overexpression of p53 protein and Ki‐67 antigen, and down‐regulation of syndecan‐1 expression in the lower part of the epithelium, are associated with dysplastic changes. Therefore, the down‐regulation of syndecan‐1 expression may be the most important reliable marker for dysplastic changes.