bluuebunny/crossref_metadata_2025 huggingface dataset:
The critical role of mouse CD4+cells in the rejection of highly disparate xenogeneic pig thymus grafts
Authors: Zhao Yong , Swenson Kirsten , Wekerle Thomas , Rodriguez‐Barbosa J. I. , Arn J. Scott , Sykes Megan
Published: March 2003

Abstract:Long‐term survival of fetal pig thymus (FP THY) grafts and efficient repopulation of mouse CD4+T cells is achieved in thymectomized (ATX) B6 mice that receive T and NK cell depletion by injection of a cocktail of mAbs (GK1.5, 2.43, 30‐H12, and PK136) and fetal pig thymus/liver (FP THY/LIV) grafts. The requirement for each mAb in this conditioning regimen in order to avoid the rejection of FP THY grafts has not yet been defined. In our present studies, CD4 cell‐depleted ATX B6 mice and euthymic MHC class II‐deficient (IIKO) mice were employed to investigate the role of mouse CD4+cells in the rejection of FP THY grafts in vivo. After grafting FP THY/LIV to CD4+cell‐depleted ATX B6 mice, efficient repopulation of mouse CD4+T cells was observed in the periphery. However, only two of four mice had remaining FP THY grafts by 17 weeks post‐implantation, and these were of poor quality, whereas four of four T and NK cell‐depleted ATX B6 mice had well‐developed FP THY grafts. Furthermore, three of four FP THY/LIV‐grafted, CD4+cell‐depleted ATX B6 mice rejected donor MHC‐matched pig skin grafts. In contrast, three of three FP THY/LIV grafted, T and NK cell‐depleted, ATX B6 mice accepted donor MHC‐matched pig skin grafts, suggesting that optimal tolerance to xenogeneic pig antigens was not achieved in mice conditioned only with anti‐CD4 mAb. ATX B6 mice treated with only anti‐CD8 mAb rejected FP THY completely by 6 weeks post‐grafting, a time when CD4+cell‐depleted ATX B6 mice had well‐vascularized FP THY grafts. In addition, when euthymic IIKO mice were pre‐treated with the standard conditioning regimen that includes four different mAbs, FP THY grafts survived and supported the repopulation of mouse CD4+T cells in the periphery, while high levels of mouse CD8+T cells developed in host thymi. These studies suggest that mouse CD4+T cells play a critical role in the acute rejection of xenogeneic FP THY grafts. Without help from CD4+cells, mouse CD8+cells, NK, NK/T, and TCR(γ/δ)+T cells do not mediate acute rejection of FP THY grafts. Furthermore, our results suggest that other cell subsets besides CD4+T cells play a role in the delayed rejection of highly disparate xenogeneic FP THY grafts.
Hyperacute rejection of vascularized heart transplants in BALB/c Gal knockout mice
Authors: Gock Hilton , Salvaris Evelyn , Murray‐Segal Lisa , Mottram Patricia , Han Wenruo , Pearse Martin J. , Goodman David J. , Cowan Peter J. , D'apice Anthony J. F.
Published: March 2003

Abstract: Pig‐to‐primate vascularized xenografts undergo hyperacute rejection (HAR). This results from pre‐formed xenoreactive antibodies directed against galactose‐α1,3‐galactose (αGal) in the donor organ and activation of the complement cascade. We describe an in vivo murine model of HAR using a BALB/c mice system devoid of histocompatibility or complement differences between donor and recipient to investigate in isolation, the effects of αGal epitope and anti‐αGal antibody interactions in causing rejection of vascularized heart transplants. Gal KO mice were immunized with rabbit red blood cell membranes to induce high anti‐αGal antibody titers that were predominantly IgM by ELISA (enzyme‐linked immunosorbent assay). When αGal‐expressing mice hearts were transplanted heterotopically into these recipients (n = 12), 67% of grafts rejected within 24 h, the majority within 16 h with histological features of HAR. In contrast, none of the grafts in the non‐immunized Gal KO recipient control group (n = 11) underwent HAR. Interestingly, approximately 50% of the remaining grafts in both the immunized and non‐immunized Gal KO recipient group were rejected between 7 and 27 days by a rejection process characterized by a dense infiltrate of macrophage/monocytes, perivascular cuffing and tissue destruction similar to recent descriptions of delayed xenograft rejection (DXR). In addition, some grafts (21.5%) continued to survive in the immunized Gal KO recipients despite the presence of anti‐αGal antibody and normal complement activity and these showed well‐preserved myocardium when harvested whilst still functioning well at days 30 or 90. No rejection was seen when Gal KO donors were used in this system (n = 4), nor when αGal‐expressing BALB/c hearts were transplanted into αGal‐expressing BALB/c recipients (n = 5). This in vivo small animal model offers the opportunity to test a variety of strategies to overcome HAR prior to more resource intensive pig‐to‐primate studies, and may provide insights into the processes similar to DXR and accommodation.
Are anti‐endothelial cell antibodies a pre‐requisite for the acute vascular rejection of xenografts?
Authors: Dorling A.
Published: March 2003

Dorling A. Are anti‐endothelial cell antibodies a pre‐requisite for the acute vascular rejection of xenografts? Xenotransplantation 2003; 10: 16–23. © Blackwell Munkgaard, 2003

Background: Vascular rejection occurring within the first few weeks after transplantation is still the major immunological barrier to the long term survival of xenografts. Currently there is no consensus about what to call this type of rejection (acute vascular rejection, delayed xenograft rejection or acute humoral xenograft rejection), nor about how to prevent or treat it.

Methods: A review of published evidence to define the heterogeneity of this phase of rejection and examine the role of antibodies, complement and graft‐infiltrating inflammatory cells.

Results: i) antibodies are always involved in acute vascular rejection; ii) this antibody‐mediated rejection may be complement‐dependent or ‐independent; iii) inflammatory cells may mediate an antibody‐ and complement‐independent phase of rejection in some small animal models (which, in its pure form cannot be called ‘vascular rejection’) iv) there remain significant questions about the relevance of ‘accommodation’ and the importance of coagulation abnormalities.

Conclusions: Without doubt, future research would be helped by distinguishing between these different forms of delayed xenograft rejection, using terminology to reflect the involvement of specific pathophysiological mechanisms. An updated classification of the stages of xenograft rejection is proposed here.
Genetic monogamy in burrowing parrotsCyanoliseus patagonus?
Authors: Masello Juan F. , Sramkova Anna , Quillfeldt Petra , Epplen Jörg Thomas , Lubjuhn Thomas
Published: March 2003

We report on a first DNA fingerprinting study of paternity in a Psittaciform bird, the burrowing parrotCyanoliseus patagonus. In two consecutive breeding seasons, a total of 49 families was sampled, of which 11 breeding pairs were investigated each of two years. Extra‐pair paternity was not encountered suggesting that burrowing parrots are socially as well as genetically monogamous. Strict genetic monogamy is comparatively rare in birds and occurs predominantly in some groups of non‐passeriformes all of which exhibit long reproductive lifespans and essential paternal care. Psittaciformes fit this pattern. We conclude that paternal care plays a crucial role in the evolution and maintenance of genetic monogamy in the study species. Cases of intraspecific brood parasitism are rarely observed.
Impaired flight ability during incubation in the pied flycatcher
Authors: Kullberg Cecilia , Metcalfe Neil B. , Houston David C.
Published: March 2003

During the breeding season, many female passerine birds increase in body mass before egg laying, maintain a relatively high body mass during incubation, and then drop back to the original level during the chick‐rearing period. The post‐hatching reduction in body mass, which can be as large as 10–20%, has been suggested to represent an adaptive mass loss to reduce wing loading, thereby increasing parental flight efficiency when chicks have hatched and have to be fed. Here we present the first study of changes in flight ability from incubation to chick rearing in birds. Wild female pied flycatchers Ficedula hypoleuca flew more slowly during incubation than during chick rearing; a 7% reduction in body mass after the chicks had hatched was associated with a 10% increase in vertical take‐off speed. Furthermore, the flight muscle size of the females tracked the reduction in wing load, suggesting that muscle size was adaptively reduced when no longer needed. Since incubation‐feeding by males reduces the time females have to spend outside the nest foraging, our results suggest that in addition to increasing female nutritional status and reducing incubation time, incubation‐feeding will also reduce predation risk during the period when females face impaired flight ability.
Changes in body condition in breeding kittiwakes Rissa tridactyla
Authors: Moe Børge , Langseth Ingveig , Fyhn Marianne , Gabrielsen Geir Wing , Bech Claus
Published: March 2003

We investigated the seasonal pattern of changes in body condition of breeding black‐legged kittiwakes Rissa tridactyla in Svalbard (79°N) to evaluate whether changes in body condition were a consequence of the energetic demands of breeding (the reproductive stress hypothesis) or of voluntary anorexia to attain lower flight costs during chick rearing (the programmed anorexia hypothesis). Adult body condition was recorded from early egg laying to fledging and was examined in relation to date (relative to hatching), sex, parental time‐budget, brood size and reproductive success. To distinguish between the two hypotheses we evaluate whether the reduction in body condition occurred during or ahead of the energetically most demanding part of the chick‐rearing period. We combine our results on changes in body condition and time‐budget with published information on field metabolic rate (FMR) and chick energy requirements from studies in the same colony.  Our calculations of adult energy requirements and energy intakes indicate that the first part of the chick‐rearing period was energetically the most demanding period, because adult energy requirement per hour spent off the nest was highest in this period, and adults were time constrained because of the need for 24‐h brooding of the chicks.  During the incubation period female body condition increased slightly, but significantly, while male body condition was stable. During the first part of the chick‐rearing period, female and male body condition decreased by 14.8% and 8.4%, respectively. During the second part of the chick‐rearing period, both male and female body condition remained stable. The reductions in body condition occurred during the phase which was suggested to be the energetically most demanding part of the chick‐rearing period, thus supporting the reproductive stress hypothesis. Parental body condition during the incubation period was positively related to the probability of successfully fledging young, providing additional support for the reproductive stress hypothesis.
Cytokine regulation of liver injury and repair
Authors: Diehl Anna Mae
Published: March 2003

Summary: By comparing the hepatic responses to tumor necrosis factor (TNF)‐a that occur during situations that promote liver injury (such as obesity or chronic exposure to ethanol) with those that occur after stimuli (such as partial hepatectomy) that lead to liver regeneration, it is apparent that hepatocytes are usually able to constrain noxious responses to TNF‐a, such as the release of reactive oxygen from mitochondria. It appears that by promptly upregulating survival genes that regulate mitochondrial mem­brane permeability, hepatocytes are usually able to constrain noxious responses, including the release of mitochondrial‐generated reactive oxygen species, that follow exposure to potentially toxic cytokines, such as TNF‐a. Indeed, transient TNF‐a‐mediated increases in ROS may even be exploited by hepatocytes to evoke a subsequent proliferative response. Thus, the healthy liver has well‐developed defense mechanisms that permit hepatocytes to adapt to cytokine‐initiated stress, protecting them from cytokine‐mediated lethality. Nevertheless, these same cytokines may cause liver injury when hepatocytes have been pre‐exposed to toxins (e.g. ethanol) that interfere with their usual protective responses. Furthermore, while transient adaptations to cytokine‐initiated stress permit hepatocytes to survive and proliferate, persistence of these anti‐apoptotic, adaptative responses (as occurs, for example, in fatty livers) may inadvertently enhance hepatocyte vulnerability to necrosis when the liver is confronted by secondary insults that promote mitochondrial membrane depolarization.
Induced leukemia and antineoplastic agent carmustine cause permanent changes in craniofacial growth of immature rats
Authors: Karsila‐Tenovuo S , Jahnukainen K , Peltomäki T , Salmi TT , Rönning O
Published: March 2003

Structured Abstract

Authors –
Karsila‐Tenovuo S, Jahnukainen K, Peltomäki T, Salmi TT, Rönning O

Objectives –
The purpose of the present study was to investigate the possible effects of untreated terminal leukemia on craniofacial growth (Study I), and also the effects of the antineoplastic agent carmustine on craniofacial growth in both leukemic and healthy rats (Study II).

Material –
A total of 367 inbred Piebald variegated rats was used.

Method –
Transmission of leukemic cells was carried out intraperitoneally at 30 days of age, and without treatment (Study I), the rats reached the terminal phase within 17 ± 1 days. Rats with induced leukemia was cured with 10 mg/kg carmustine (BCNU) given on days 6 and 13 following cell transmission (Study II), the rats remaining in remission until they were killed at 100 days of age. Final weight was recorded and 12 craniofacial dimensions and tibial length were measured with a digital sliding caliper.

Results –
The results showed that the effect of untreated terminal rat leukemia (Study I) on craniofacial growth differed between the genders. Male rats showed clearly reduced dimensions of facial structures and also retarded general body growth, whereas females showed differences mainly in general body growth. The effect of cured leukemia (Study II) as such was minor, while BCNU had a strong and permanent reducing effect on both craniofacial and general body growth in both genders.

Conclusion –
We suggest that the results in Study I came both from a direct effect of leukemia and an indirect effect of untreated terminal leukemia through malnutrition. The alkylating agent BCNU seemed to be the main cause of permanent craniofacial and general growth retardation in Study II.
Mast cells in innate immunity
Authors: Mekori Yoseph A. , Metcalfe Dean D.
Published: March 2003

Summary: Mast cells are known to be the main effector cells in the elicitation of the IgE‐mediated allergic response. The specific location of mast cells within tissues that interface the external environment, and the extent of their functional capacity, including the ability to phagocytose and to produce and secrete a wide spectrum of mediators, have led investigators to propose a potential role for mast cells in innate immune responses. Certain microorganisms have been found to interact either directly or indirectly with mast cells. This interaction results in mast cell activation and mediator release which elicit an inflammatory response or direct killing leading to bacterial clearance. The in vivo relevance of these in vitro observations has been demonstrated by the use of complement‐deficient and/or mast cell‐deficient and mast cell‐reconstituted mice. It thus has been shown that both C3 and mast cell‐ and tumor necrosis factor‐a‐dependent recruitment of circulating leukocytes with bactericidal properties are crucial to a full response in certain models of acute infection. Modulation of mast cell numbers in vivo was also found to affect the host response against bacterial infection. Thus, mast cells do have a role in innate immunity in defined animal models of bacterial infection. Whether mast cells participate in innate immune responses in the protection of the human host against bacteria remains to be determined.
Ligand interactions by activating and inhibitory Ly‐49 receptors
Authors: Nakamura Mary C. , Seaman William E.
Published: March 2003

Summary: Natural killer (NK) cells express families of homologous receptors, members of which either activate or inhibit NK cells. We demonstrate that mouse Ly‐49D is an activating receptor for the MHC antigen H2‐Dd, which is also a ligand for the related inhibitory receptor Ly‐49A. To compare and contrast their interactions with class I MHC ligand, we studied each of these receptors expressed in a rat NK‐cell line, RNK‐16, for their capacity to recognize wild‐type or mutated H2‐Dd. Our studies with Ly‐49A reveal that functional interaction with H2‐Dd depends on residues in the floor of the H2‐Dd peptide‐binding groove. The recent co‐crystal of Ly‐49A with H2‐Dd indicates that these are not contact residues, thus they may contribute to allelic specificity through conformational changes in H2‐Dd. We found that structural requirements for functional recognition of H2‐Dd by Ly‐49D differ markedly from those for recognition by Ly‐49A. We note that H2‐Dd expression on certain target cells is not sufficient to activate lysis mediated by Ly‐49D, though the additional requirements for functional interaction are not yet identified. Here we review recent studies of Ly‐49 receptor ligand specificities and their molecular basis. The functions of these related receptors with opposing functions and shared allospecificity remains unclear.

This work was supported by the Veterans Administration. M.C.N. is also supported by the Arthritis Foundation and the American Cancer Society. W.E.S. received NIH grant RO1 CA69299. We thank J.C. Ryan for communication of unpublished results. We thank H. Houtkooper and T. Ferrin for the molecular graphics image in Fig. 3, which was created with the MidasPlus modeling system, supported by the NIH grant P41‐RR‐01081.
2B4 (CD244) and CS1: novel members of the CD2 subset of the immunoglobulin superfamily molecules expressed on natural killer cells and other leukocytes
Authors: Boles Kent S. , Stepp Susan E. , Bennett Michael , Kumar Vinay , Mathew Porunelloor A.
Published: March 2003

Summary: 2B4 is a member of the CD2 subset of the immunoglobulin superfamily molecules expressed on natural killer (NK) cells and other leukocytes. It is the high affinity ligand for CD48. Engagement of 2B4 on NK‐cell surfaces with specific antibodies or CD48 can trigger cell‐mediated cytotoxicity, interferon‐γ secretion, phosphoinositol turnover and NK‐cell invasiveness. The function of 2B4 in CD8+ T cells and myeloid cells remains unknown. The cytoplasmic domain of 2B4 contains unique tyrosine motifs (TxYxxV/I) that associate with src homology 2 domain‐containing protein or signaling lymphocyte activation molecule (SLAM)‐associated protein, whose mutation is the underlying genetic defect in the X‐linked lymphoproliferative disease (XLPD). Impaired signaling via 2B4 and SLAM is implicated in the immunopathogenesis of XLPD. CS1 is a novel member of the CD2 subset that contains two of the unique tyrosine motifs present in 2B4 and SLAM. Signaling through 2B4, CS1 and other members of the CD2 subset may play a major role in the regulation of NK cells and other leukocyte functions.

This research was supported in part by NIH grant AI38938 and AI25041. We are grateful to M. Kim, P. Kumaresan, and S. Chuang for manuscript review.
Induction and mechanism of action of transforming growth factor‐β‐secreting Th3 regulatory cells
Authors: Weiner Howard L.
Published: March 2003

Summary: Th3 CD4+ regulatory cells were identified during the course of investigating mechanisms associated with oral tolerance. Different mechanisms of tolerance are induced following oral antigen administration, including active suppression, clonal anergy and deletion. Low doses favor active suppression whereas high doses favor anergy/deletion. Th3 regulatory cells form a unique T‐cell subset which primarily secretes transforming growth factor (TGF)‐β, provides help for IgA and has suppressive properties for both Th1 and Th2 cells. Th3 type cells are distinct from the Th2 cells, as CD4+ TGF‐β‐secreting cells with suppressive properties have been generated from interleukin (IL)‐4‐deficient animals. In vitro differentiation of Th3 cells from Th precursors from T‐cell antigen receptor (TCR) transgenic mice is enhanced by culture with TGF‐β, IL‐4, IL‐10, and anti‐IL‐12. Th3 CD4+ myelin basic protein regulatory clones are structurally identical to Th1 encephalitogenic clones in TCR usage, MHC restriction and epitope recognition, but produce TGF‐β with various amounts of IL‐4 and IL‐10. Because Th3 regulatory cells are triggered in an antigen‐specific fashion but suppress in an antigen‐non‐specific fashion, they mediate “bystander suppression” when they encounter the fed autoantigen at the target organ. In vivo induction of Th3 cells and low dose oral tolerance is enhanced by oral administration of IL‐4. Anti‐CD86 but not anti‐CD80 blocks the induction of Th3 cells associated with low dose oral tolerance. Th3 regulatory cells have been described in other systems (e.g. recovery from experimental allergic encephalomyelitis) but may be preferentially generated following oral antigen administration due to the gut immunologic milieu that is rich in TGF‐β and has a unique class of dendritic cells. CD4+CD25+ regulatory T‐cell function also appears related to TGF‐β.
Mast cells, basophils, and eosinophils: distinct but overlapping pathways for recruitment
Authors: Bochner Bruce S. , Schleimer Robert P.
Published: March 2003

Summary: Mast cells, basophils and eosinophils are bone marrow‐derived cells that contribute to a variety of allergic and other immune responses. For example, they are relatively abundant at mucosal sites where allergic inflammation is occurring, and their activation and release of preformed and newly‐generated mediators at these sites is considered central to the pathophysiology of allergic diseases. Given their involvement in allergic and other diseases, it is important to understand how these cells are selectively recruited into tissues. These cells share many phenotypic features, including those involved in adhesion and migration, yet their localization within a given tissue can be quite distinct. In addition, there are examples of selective recruitment of one cell type without the others. From studies with human cells, it is now clear that mast cells, basophils and eosinophils share a number of recruitment pathways with one another and with other cells, but that each possesses unique adhesion and migration responses that can contribute to their preferential accumulation. This review will focus on cell surface structures implicated in adhesion and migration responses of human mast cells, basophils and eosinophils. Both shared and selective expression of these molecules will be highlighted, as well as differences in their relative levels of expression. Cell type‐specific stimuli that alter adhesion and migration responses will also be considered.

The authors thank Bonnie Hebden for assistance in the preparation of this manuscript.
Role of mast cells in intestinal mucosal function: studies in models of hypersensitivity and stress
Authors: Yu Linda C. H. , Perdue Mary H.
Published: March 2003

Summary: A single layer of epithelial cells lines the gastrointestinal tract, forming a critical barrier between the luminal contents, which includes antigens and other noxious substances, and the body proper. It has become clear in recent years that the role of mast cells in the gastrointestinal mucosa is not only to react to antigens, but also to actively regulate the barrier and transport properties of the intestinal epithelium. Mucosal mast cells respond to both IgE/antigen‐dependent and non‐IgE‐dependent stimulation, releasing bioactive mediators into adjacent tissues where they induce physiological responses. Studies in models of hypersensitivity and stress have provided evidence that changes in mucosal function are due to either direct action of mast cell mediators on epithelial receptors and/or indirect action via nerves/neurotransmitters.

Studies conducted in the authors' laboratories were funded by grants from the Canadian Institutes of Health Research and the Crohn's and Colitis Foundation of Canada.
Travels along the viral–immunobiology highway
Authors: Oldstone Michael B. A.
Published: March 2003

Summary: Michael Oldstone began his biomedical research career over three decades ago, showing contrary to established scientific dogma, the host was not tolerant but made a specific antiviral immune response during persistent virus infections. Further, the immune response to the virus actually caused tissue damage and disease, the first observation that several manifestations ordinarily accompanying infections were due to the host's antiviral immune response. These observations made originally with lymphocytic choriomeningitis virus (LCMV) and murine retroviruses were extended to other microbial infections including those in humans. Buildings on this work, he showed that antibodies to virus could recognize similar amino acid sequences or motifs found in host/cell proteins and cause disease. This cross‐reactivity, referred to as molecular mimicry, has and is now been extensively studied by many laboratories. Another mechanism by which persistent virus infection produced disease was uncovered by cocumenting that viruses could alter the differentiation or “luxury” function of cells with causing cell destruction, thereby altering homeostasis. Finally, Oldstone was one of the first to show that viruses caused immunosuppression, abrogated immunologic surveillance resulting in viral persistence, work carried out long before HIV was discovered. He has also defined host‐cell receptors for several viruses. In recent studies, host‐cell receptor used by LCMV strains or variants that cause persistence have been identified. This led to observations that a single amino acid on the viral glycoprotein provides the infectious agent a selective ability ot displace extra‐cellular matrix molecule, bind to and infect dendritic cells leading to their inability to act as antigen presenting cells thereby aborting the host's ability to generate the antiviral immune response required to clean the infection.
Human hematopoietic lineage commitment
Authors: Payne Kimberly J. , Crooks Gay M.
Published: March 2003

Summary: The ultimate goal of developmental immunology is to understand the normal processes that give rise to the immune system in order to diagnose and develop effective treatments for diseases that occur as a consequence of immune system defects. Central to achieving this goal is understanding the complex interplay between microenvironmental signals and transcription factors that direct human hematopoietic differentiation and lineage commitment. The ability to isolate highly purified populations of human hematopoietic cells at critical points in differentiation make it possible to answer very specific questions about the hematopoietic process and lineage restriction. This review describes the use of surface immunophenotypes to identify human hematopoietic cells at particular points in differentiation or with particular patterns of lineage restriction. Culture models are discussed in the context of the ability to detect, characterize and determine the lineage potential of human hematopoietic stem cells and progenitors. Variations in hematopoeises that correspond to ontogeny will be examined. Potential roles for the HOX and Ikaros proteins in human lineage commitment will be considered. Also included will be discussion of a number of factors that provide challenges to experimental design, to experimental interpretation, and to the development of a comprehensive model of human hematopoiesis.
Role of thymic organ structure and stromal composition in steady‐state postnatal T‐cell production
Authors: Petrie Howard T.
Published: March 2003

Summary: The most conspicuous period of cellular proliferation and differentiation occurs during the embryonic stage of development. In some cell lineages, however, including T lymphocytes, this process must continue postnatally and throughout life. Under ordinary circumstances, postnatal T‐cell production occurs in the thymus, and can be separated into five functional phases. The first is recognition of thymus‐derived recruitment signals by multilineage progenitors in the bloodstream, followed by their extravasation and entry into the organ. Second is the lymphopoietic process, i.e. the expansion of this small number of blood‐derived progenitors to produce the raw materials for all subsequent phases. Third is the screening of these cellular products for the ability of their T‐cell receptors to appropriately recognize major histocompatibility/peptide ligands, i.e. positive and negative selection. Fourth is functional maturation, a process that follows but is distinct from positive selection. Finally, cells that successfully undergo all of the prior processes must be induced to leave the thymus and enter the peripheral lymphoid pool. From the above, it can be seen that all the hematopoietic components of the thymus are transient, with uncommitted progenitors entering and lineage committed progeny being exported or removed. This process reveals a subtle but critically important fact about the nature of the thymus, namely that the functional components of the thymus are not the hemato‐lymphoid cells, but rather the stable (stromal) elements that induce their differentiation. Understanding the nature of these stromal elements, and the signals they deliver to nascent T lymphocytes, is therefore critical not only for understanding how T lymphocytes are produced normally but, by analogy, what goes wrong in congenital, acquired, or age‐associated deficiencies in T‐lymphocyte production.
The role of CD45+CD4+CD3– cells in lymphoid organ development
Authors: Cupedo Tom , Kraal Georg , Mebius Reina E.
Published: March 2003

Summary: In the last 10 years the continuing search for gene function has yielded many mutant mice that unexpectedly showed a complete lack of lymph nodes and/or Peyer's patches. With the realization that all these functionally highly diverse genes are involved at some point in the development of lymphoid organs, the challenge now is to assign a function to the molecules involved in lymphoid organ development. It will be important to determine the sequence of molecular events and assign this to the cellular events that lead to an accumulation of hematopoietic cells in one location, ultimately forming an organized lymphoid organ. Here we will focus on CD45+CD4+CD3– cells that are the early colonizing cells in lymph nodes and Peyer's patches and develop a hypothetical model of their contribution to the creation of organized lymphoid structures.
Fc receptor homologs: newest members of a remarkably diverse Fc receptor gene family
Authors: Davis Randall S. , Dennis jr Glynn , Odom Mary R. , Gibson Andrew W. , Kimberly Robert P. , Burrows Peter D. , Cooper Max D.
Published: March 2003

Summary: Newfound relatives of the classical Fc receptors (FcR) have been provisionally named the Fc receptor homologs (FcRH). The recent identification of eight human and six mouse FcRH genes substantially increases the size and functional potential of the FcR family. The extended family of FcR and FcRH genes spans ∼15 Mb of the human chromosome 1q21–23 region, whereas in mice this family is split between chromosomes 1 and 3. The FcRH genes encode molecules with variable combinations of five subtypes of immunoglobulin (Ig) domains. The presence of a conserved sequence motif in one Ig domain subtype implies Ig Fc binding capability for many FcRH family members that are preferentially expressed by B lineage cells. In addition, most FcRH family members have consensus tyrosine‐based activating and inhibitory motifs in their cytoplasmic domains, while the others lack features typical of transmembrane receptors. The FcRH family members, like the classical FcRs, come in multiple isoforms and allelic variations. The unique individual and polymorphic properties of the FcR/FcRH members indicate a remarkably diverse Fc receptor gene family with immunoregulatory function.
The role of Tec family kinases in T cell development and function
Authors: Lucas Julie A. , Miller Andrew T. , Atherly Luana O. , Berg Leslie J.
Published: March 2003

Summary: Three members of the Tec family kinases, Itk, Rlk and Tec, have been implicated in signaling downstream of the T cell receptor (TCR). The activity of these kinases in T cells has been shown to be important for the full activation of phospholipase C‐γ1 (PLC‐γ1). Disruption of Tec family signaling in Itk–/– and Rlk–/–Itk–/– mice has multiple effects on T cell development, cytokine production and T‐helper cell differentiation. Furthermore, mice possessing mutations in signaling molecules upstream of PLC‐γ1, such as Src homology 2 (SH2) domain‐containing phosphoprotein of 76 kDa (SLP‐76), linker for activation of T cells (LAT) and Vav1, or in members of the nuclear factor for activated T cells (NFAT) family of transcription factors, which are downstream of PLC‐γ1, have been found to have similar phenotypes to Tec family‐deficient mice, emphasizing the importance of this pathway in regulating T cell activation, differentiation and homeostasis.
Cloning of the rat ADAMTS‐1 gene and its down regulation in endothelial cells in cirrhotic rats
Authors: Diamantis Ioannis , Lüthi Michael , Hösli Miriam , Reichen Jürg
Published: March 2003

Abstract: Aims: This study was undertaken in order to identify genes which are regulated during the process of liver fibrosis. Methods: The differential display method and RNA from rat endothelial cells before and after induction of cirrhosis were used. Results: A 496bp fragment, which was down regulated in liver endothelial cells from a cirrhotic animal, was cloned. The cloned fragment showed a 95% homology with the newly cloned mouse ADAMTS‐1 gene (a disintegrin and metalloproteinase with thrombospondin motifs), which is implicated in inflammation. The fragment was found to span the 3′ of exon 6, the whole exon 7 and the 5′ of exon 8. Sequencing of the entire coding region of the rat gene showed a 94% homology at the nucleic acid level and 96% homology at the amino acid level. The sequences responsible for the function of the protein were conserved. Northern blot analysis, using the cloned fragment as a probe, confirmed the finding that the gene was down‐regulated in endothelial cells derived from livers of cirrhotic animals. In situ PCR analysis localised the ADAMTS‐1 gene in the liver endothelial cells from normal animals. Conclusions: Regulation of the expression of genes which belong to the metalloproteinase family in liver endothelial cells might be important in the development of liver cirrhosis.
Effects of idoxifene and estradiol on NF‐κB activation in cultured rat hepatocytes undergoing oxidative stress
Authors: Omoya Toshihiro , Shimizu Ichiro , Zhou Yajun , Okamura Yoshihito , Inoue Hiroshi , Lu Guangming , Itonaga Mina , Honda Hirohito , Nomura Masahiro , Ito Susumu
Published: March 2003

Abstract: Background/Aims: Idoxifene is a tissue‐specific selective estrogen receptor modulator. Estradiol is a potent endogenous antioxidant, and nuclear factor κB (NF‐κB) is a key transcription factor that induces multiple genes in response to inflammation or oxidative stress. The aim of this study was to explore the inhibitory effects of idoxifene and estradiol on NF‐κB activation in hepatocytes in a state of oxidative stress. Methods: Lipid peroxidation was induced in cultured rat hepatocytes by incubation with ferric nitrilotriacetate solution. NF‐κB activity was evaluated by electrophoretic mobility shift assay. Results: The oxidative stress‐induced activation of NF‐κB and degradation of IκB‐α were maximal at 3–5 h, with an increase in lactate dehydrogenase (LDH) and malondialdehyde (MDA) secretion into the culture medium. Treatment with idoxifene and estradiol inhibited IκB‐α degradation and NF‐κB activation through the attenuation of hepatocyte oxidative bursts and decreased extracellular levels of LDH and MDA. In addition, idoxifene and estradiol inhibited lipid peroxidation in rat liver mitochondria. A potent NF‐κB inhibitor, pyrrolidine dithiocarbamate, prevented NF‐κB activation by inhibition of IκB‐α degradation and decreased LDH and MDA levels, suggesting that NF‐κB might be a regulator in a genetic response to increase oxidative stress‐induced hepatic injury. Conclusions: These findings suggest that idoxifene and estradiol function as antioxidants and protect hepatocytes from inflammatory cell injury.
Endotoxin clearance and its relation to hepatic and renal disturbances in rats with liver cirrhosis
Authors: Nakatani Yoshihiro , Fukui Hiroshi , Kitano Hiroyuki , Nagamoto Issei , Tsujimoto Tatsuhiro , Kuriyama Shigeki , Kikuchi Eiryo , Hoppou Kazushige , Tsujii Tadasu
Published: March 2003

Abstract: Background/Aims: Little is known about endotoxin clearance and secretion of cytokines from macrophages in liver cirrhosis. The aims of this study were to investigate the relationship of endotoxin clearance and release of tumor necrosis factor α by various macrophages to hepatic and renal disturbances in liver cirrhosis. Methods: Male Sprague‐Dawley rats were given 0.04% thioacetamide orally for 6 or 12 months. The organ distribution of infused [3H]‐endotoxin (10 μg/kg b.w.) was analyzed at 30 min or at 24 h. Uptake of [3H]‐endotoxin and secretion of tumor necrosis factor α by Kupffer cells, splenic macrophages and peripheral blood monocytes (1×104 cells/ml) from cirrhotic and control rats were determined. Results: In cirrhotic rats, more endotoxin was left in the body and more endotoxin accumulated in the spleen and kidney, and thus was related to elevation of serum total bilirubin, aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, creatinine and tumor necrosis factor α. Endotoxin uptake and tumor necrosis factor α release by the Kupffer cells were decreased and those by the splenic macrophages and peripheral blood monocytes were increased in cirrhotic rats. Conclusions: In liver cirrhosis, impaired clearance of endotoxin together with increased secretion of tumor necrosis factor α by extrahepatic macrophages may play an important role in the progression of hepatic and renal disturbances.
Effects of salviainolic acid A (SA‐A) on liver injury: SA‐A action on hepatic peroxidation
Authors: Liu Ping , Hu Yiyang , Liu Chenghai , Liu Cheng , Zhu Dayuan
Published: March 2003

Abstract: Background/Aims: This study aimed to investigate the actions of salviainolic acid A (SA‐A), an antiperoxidative component of Salvia miltiorrhiza (Sm), on rat liver injury and fibrosis. Methods: Acute and chronic rat liver injury models were established using carbon tetrachloride (CCl4). After 48 h (acute) or during 6 weeks of CCl4 injection, rats were further divided and treated with biphenyl dimethyl‐dicarboxylate (BDD) or colchicine, as a control antifibrotic treatment, with Sm, a herbal compound, or SA‐A, a water‐soluble extract of Sm. Liver function was investigated by assessing alanine transaminase (ALT) and aspartate transaminase (AST) activities, histological analysis, hydroxyproline (Hyp) and malondiadehyde (MDA) content. In vitro, isolated cultured hepatocytes were injured with CCl4 gas for 24 h, followed by treatment with either vitamin E or various concentrations of SA‐A. The extent of hepatocyte injury was monitored by analyzing various lipid peroxidative parameters such as superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), lactase dehydrogenase (LDH), and glutathione peroxidase (GSH‐PX) levels in hepatocyte supernatants. Results: SA‐A significantly decreased abnormal serum ALT activity both in acutely and chronically injured rat livers, decreased abnormal serum AST activity, Hyp and MDA content and attenuated hepatic collagen deposition. After CCl4 incubation and injury, the activities of AST, ALT CAT, GSH‐PX and LDH and MDA content in hepatocyte supernatants increased significantly, but GSH levels decreased significantly. SA‐A markedly improved these pathological changes in a dose‐dependent manner. 10−4 mol/l SA‐A had stronger inhibitory action than vitamin E. Conclusions: Our studies suggest that SA‐A has antiperoxidative effects on injured hepatocytes in liver injury and fibrosis induced by CCl4.
Ubiquitin and hepatocellular carcinoma
Authors: Shirahashi Hitoshi , Sakaida Isao , Terai Shuji , Hironaka Koji , Kusano Noriyoshi , Okita Kiwamu
Published: March 2003

Abstract: Background/Aim: Ubiquitin (Ub)‐dependent degradation of regulatory proteins controls many cellular processes such as cell cycle progression, morphogenesis and signal transduction. In this study, we evaluated the meaning of ubiquitination in chronic liver diseases, especially human hepatocellular carcinoma, with regard to recurrence.

Methods: A total 74 of liver tissues (8 of chronic hepatitis [CH], 9 of liver cirrhosis [LC], 7 of dysplastic nodule low grade (DSL), or dysplastic nodule high grade (DSH) and 50 of hepatocellular carcinoma [HCC]) were analyzed for ubiquitination by immunohistochemisty. Cell proliferation was also analyzed using Ki‐67 staining. As a comparative marker for progression of HCC, PIVKA‐II (protein induced by vitamin K absence‐II) was employed to examine the recurrence rate of HCC.

Results: Ubiquitin (Ub) was positive in nuclei and cytoplasm of HCC in immunohistochemistry. The labeling index (L.I.) of ubiquitination was significantly higher with HCC than with other chronic liver diseases and tended to correlate with the lack of poorly‐ differentiated of HCC. The L.I. of Ki‐67 staining was also correlated (P < 0.0001) with that of ubiquitination. The hepatocellular carcinoma (HCC) samples from potentially curatively operated patients having a ubiquitination L.I. of more than 20% suffered significantly higher recurrence of HCC than did patients with an L.I. of less than 20%. On the other hand, PIVA‐II did not show such a difference.

Conclusion: Ubiquitin (Ub) may reflect the growth activity of neoplasms and will be a possible new predictive marker for the recurrence of human hepatocellular carcinoma after potentially curative operation.
Interleukin‐1, interleukin‐10 and tumour necrosis factor‐alpha gene polymorphisms in hepatitis C virus infection: an investigation of the relationships with spontaneous viral clearance and response to alpha‐interferon therapy
Authors: Patricia K. Constantini  , Marta Wawrzynowicz‐Syczewska  , Michael Clare , Anna Boron‐Kaczmarska  , Ian G. McFarlane  , Mathew E. Cramp  , Peter T. Donaldson
Published: March 2003

Abstract: Background/Aims: Though there is a consensus that the HLA DQB1*0301 allele is important in untreated HCV clearance, this association is not universal and a number of genes outside the major histocompatibility complex may also play a role in host responses to HCV infection. Prime candidates, at present, are the genes encoding pro‐inflammatory and immuno‐regulatory cytokines. The aim of this study was to investigate the relationship between a number of these candidate genes and both spontaneous and treatment related clearance of hepatitis C virus infection. Methods: Three members of the interleukin‐1 gene family: IL‐1A, IL‐1B and IL‐1RN, three polymorphic sites in the interleukin‐10 gene promoter (− 1082, − 819, − 592) and two in the tumour necrosis factor‐alpha promoter (− 308, − 238) were studied in two independent DNA banks, each with appropriate controls. Standard PCR‐based genotyping techniques were used. Results: No significant difference in the distribution of any of the polymorphisms was found in either study set. Conclusions: These findings in two large groups suggest that future investigations should focus on other candidate genes and may support the view that MHC‐encoded susceptibility to chronic HCV infection may be determined by MHC class II rather than MHC class III genes.
Whole inactivated SIV virion vaccines with functional envelope glycoproteins: safety, immunogenicity, and activity against intrarectal challenge
Authors: Lifson J.D. , Piatak M. , Rossio J.L. , Bess J. , Chertova E. , Schneider D. , Kiser R. , Coalter V. , Poore B. , Imming R. , Desrosiers R.C. , Henderson L.E. , Arthur L.O.
Published: March 2003

Abstract: A novel type of whole inactivated simian immunodeficiency virus (SIV) virion vaccine immunogen with functional envelope glycoproteins was evaluated, without adjuvant, in rhesus macaques. Immunogens included purified inactivated virions of SIVmac239, a designed mutant of SIVmac239 with gp120 carbohydrate attachment sites deleted (SIVmac239 g4,5), and SIVmneE11S. The vaccines were noninfectious, safe, and immunogenic, inducing antibody responses and cellular responses, including responses by CD8+ lymphocytes. Interpretation of protective efficacy following intrarectal challenge was complicated by incomplete take of the challenge in some SIV naïve controls.
Analysis of flows in a ladle with gas‐stirred melt
Authors: Xia J. L. , Ahokainen T. , Holappa L.
Published: March 2003

A numerical study of 2 phase flows in a ladle with gas stirred liquid Wood’s metal is carried out using the CFX code. A cylindrical model ladle containing the molten metal is considered, and nitrogen is injected vertically upward through a nozzle centrally located at the bottom. An Eulerian 2‐phase model is employed. The effects of drag, lift and turbulent dispersion forces are taken into account for the bubble‐liquid interface interactions. Different drag and lift force coefficients have been examined to find a reasonable set of values for these parameters. Predictions are compared against the experimental data measured in an identical model ladle by Xie and coworkers for the mean axial and radial liquid velocities, the bubble rising velocity, and gas volume fraction at various heights. Results show that the mathematical model can reasonably well predict flows in the liquid region, but, for the cases considered, a relatively large deviation exists in the gas‐liquid plume. The present results accumulate information of CFD in modelling gas‐stirred flows occurring in metallurgical processes.
Chemical potentials of oxygen within 3‐phase assemblages of the system CaO+SiO2+FexO
Authors: Enaka T. , Uchida Y. , Hasegawa H. , Naito M. , McLean A. , Iwase M.
Published: March 2003

Within the system CaO+SiO2+FexO, there are a number of 3‐phase assemblages as given below; (1) CaO+Ca3SiO5+liquid, (2) Ca3SiO5+Ca2SiO4+liquid, (3) Ca2SiO4+Ca3Si2O7+liquid, (4) Ca3Si2O7+CaSiO3+liquid, and (5) CaSiO3+SiO2+liquid. Chemical potentials of oxygen within such assemblages have been determined by using an electrochemical technique incorporating zirconia solid electrolyte.
Novel concept of disposable emf sensors for in situ measurements of solute contents of liquid metals in metal‐refining processes*
Authors: Turkdogan E. T.
Published: March 2003

The novel feature of this unique disposable solute emf sensor for liquid metals, described in this paper, is in the use of a molten ionic polymer, e.g., aluminosilicate, as the sensor electrolyte. Theoretically, with this type of molten ionic electrolyte, it should be possible to measure the various solute contents in liquid metals. Calculated examples are given in this paper for the emf sensor measurements of Al, C, Ca, Cr, H, Mg, N, O, P, Si and S in liquid steel and/or hot metal. Examples are also given for the H, O, P and S measurements in liquid copper and H in liquid aluminium.
Quantification of induced roll magnetic separation of mineral sands
Authors: Naik Pradyumna K.
Published: March 2003

In the present work the effect of variables and forces acting on a magnetic particle passing through induced roll magnetic separator has been discussed. The sensitivity of important variables, namely input current, roll speed and feed rate have been assessed and quantified using statistical techniques.