bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Analysis and Containment Canister Life Prediction for a Brayton Engine Solar Receiver for Space Station
Authors: Strumpf H. J. , Avanessian V. , Ghafourian R.
Published: June 2008

A study has been conducted on the design and development of a solar receiver to be used for electrical power production for Space Station. The receiver incorporates integral thermal storage, using a eutectic mixture of LiF and CaF2 as a solid-to-liquid phase-change material (PCM). The design comprises a cylindrical receiver cavity. The walls of the cavity are lined with a series of working fluid tubes running the length of the cavity. The PCM is enclosed in individual, sealed metallic containment canisters which are stacked and brazed to the tubes. The compartmentalization of the PCM localizes void formation upon freezing. An additional attribute of compartmentalization is that a containment canister failure affects only that canister; the receiver continues to operate with only a minute loss of capacity. Nevertheless, a considerable effort has been expended to ensure that the containment canisters will survive a 30-year life. A detailed analytical procedure was developed to evaluate the canister creep strain accumulated in 30 years. This accumulated creep strain, which is in the range of 0.03 to 0.79 percent, compares favorably with the preliminary value of four percent for the canister material allowable 30-year creep rupture ductility.
Incompressible Navier-Stokes Computation of the NREL Airfoils Using a Symmetric Total Variational Diminishing Scheme
Authors: Yang S. L. , Chang Y. L. , Arici O.
Published: June 2008

The purpose of this paper is to present a numerical study of flow fields for the NREL S805 and S809 airfoils using a spatially second-order symmetric total variational diminishing scheme. The steady two-dimensional flow is modeled as turbulent, viscous, and incompressible and is formulated in the pseudo-compressible form. The turbulent flow is closed by the Baldwin-Lomax algebraic turbulence model. Numerical solutions are obtained by the implicit approximate-factorization method. The accuracy of the numerical results is compared with the Delft two-dimensional wind tunnel test data. For comparison, the Eppler code results are also included. Numerical solutions of pressure and lift coefficients show good agreement with the experimental data, but not the drag coefficients. To properly simulate the post-stall flow field, a better turbulence model should be used.
Source and Sink Method of Solution of Two-Dimensional Phase Change for Energy Storage
Authors: Li Hongjun , Hsieh C. K. , Goswami D. Y.
Published: June 2008

A source and sink method has been developed for the solution of heat transfer with phase change in two dimensions. In this method, the heat transfer in one direction is decoupled from that in the other direction by changing the second partial differential in the direction where the phase change is less dominant to a finite difference form and solving the problem in the other direction with an analytical solution that accounts for the motion of the interface in a phase-change problem. The solution developed in this paper is thus independent of the equations used to represent the interface as well as the conditions imposed on the boundaries. In the present paper, the method has been applied to the tracking of a single melting front formed by different phases assuming equal properties. The method has been demonstrated to be accurate, convergent, and stable by numerical computations as well as experimental measurements. Extension of the method to more general problems has also been discussed.
An Energy Delivery Efficiency Index to Evaluate Simultaneous Heating and Cooling Effects in Large Commercial Buildings
Authors: Reddy T. A. , Kissock J. K. , Katipamula S. , Claridge D. E.
Published: June 2008

HVAC systems of large commercial buildings consume energy in excess of the sum total of the building loads. This excess energy use is due to the fact that a single air-handler unit in a HVAC system, having to provide conditioned air at different supply temperatures to different zones in the building, can do so only by resorting to either (a) a certain amount of mixing of cold and hot air streams as in dual-duct systems or (b) to terminal reheating in single-duct systems. This mixing of cold and hot air streams or terminal reheating result in an energy penalty which can be minimized by say, converting a constant air volume (CAV) system to a variable air volume (VAV) system, but it cannot be entirely eliminated. This paper proposes an index, called the Energy Delivery Efficiency (EDE), which characterizes this penalty and rates the energy performance of HVAC systems on an absolute scale. We develop the mathematical basis of the EDE approach for both one-zone and two-zone buildings, that allows determining the variation of the ideal EDE with outdoor temperature for a specific building. Year-long measured whole-building cooling and heating energy use data from two retrofitted buildings are finally used to illustrate differences between actual EDE plots of CAV and VAV systems, how they compare with the ideal EDE of a two-zone building, and how the approach can provide diagnostic insights into HVAC system efficiency in specific buildings.
Experience With a Solar Heating ATES System for a University Building
Authors: Hahne E. , Hornberger M.
Published: June 2008

At Stuttgart University, a solar heating system for an office building with laboratories and lecture rooms was installed in 1985. It consists of 211 m2 of unglazed solar collectors, a 1050 m3 water-flooded pebble bed heat store, and a heat pump. Heat can be supplied to the store from the solar collectors or from a power station (as waste heat). The whole system has worked successfully for five years under varied strategies. In the first two heating periods, the heating strategy was aimed to collect as much solar energy as possible. Thus, about 60 percent of the heat demand could be covered by solar energy; but the yearly heat pump coefficient of performance (COP) was only around 2.76. With an improved heat pump, a monthly COP of 3.6 was obtained. Heat losses from the storage amounted to about 20 percent.
Kinetics and Mechanism of Zn(II) Ion Electroreduction in the Presence of Vetranal
Authors: Nieszporek Jolanta , Gugała-Fekner Dorota , Sieńko Dorota , Saba Jadwiga , Nieszporek Krzysztof
Published: June 2008

The two-step reduction of Zn(II) ions at a dropping mercury electrode in 1 M NaClO4 with addition of vetranal was examined using dc polarography, cyclic voltammetry and impedance measurements. Small changes of reversible potential of half-wave, Er1/2, values indicate that the Zn(II)-vetranal complexes formed in the solution are very unstable. A stepwise character of electron transfer in the Zn(II) ion reduction was established. The catalytic activity of vetranal is stronger in the first step of electron transfer than in the second one. The linear dependence of the true rate constant for the forward reaction, ktf, of Zn(II) electroreduction versus relative surface excess, Γ′, of vetranal at a given potential in the reaction plane, Φr, was interpreted in terms of a "bridging model".
THE VIRTUAL MAGNETIC KAUFFMAN BRACKET SKEIN MODULE AND SKEIN RELATIONS FOR THE f-POLYNOMIAL
Authors: ISHII ATSUSHI , KAMADA NAOKO , KAMADA SEIICHI
Published: June 2008

We introduce the virtual magnetic Kauffman bracket skein module, and show how to find a skein relation for the f-polynomial through the module. Furthermore, we give a unified approach to constructions of skein relations which hold under certain conditions.
ON A BALL IN A METRIC SPACE OF KNOTS BY DELTA MOVES
Authors: HORIUCHI SUMIKO
Published: June 2008

We consider the metric space of all knots on which the distance is defined by delta moves. We show that for any two knots K1 and K2 with delta distance k and for any natural numbers ℓ and m with ℓ + m = k, the intersection of the ball of radius ℓ centered at K1 and the ball of radius m centered at K2 contains infinitely many knots. We also consider the problem whether or not the center of a given ball is unique.
INVARIANTS OF 3-MANIFOLDS ASSOCIATED TO 3-COCYCLES OF GROUPS
Authors: OSPEL CYRILLE
Published: June 2008

We study relations between group cohomologies and 3-manifold invariants. We first give a combinatorial construction of 3-manifold invariants using weight systems. We give examples of weight systems arising from a particular group cohomology. In the second part we show that these invariants can be obtained in a functorial way.
A FORMULATION OF THE BOUNDARY ELEMENT METHOD FOR ACOUSTIC RADIATION AND SCATTERING FROM TWO-DIMENSIONAL STRUCTURES
Authors: CHEN Z.-S. , WAUBKE H.
Published: June 2008

A code for the boundary element method (BEM) for two-dimensional acoustic radiation and scattering problems is developed. To overcome the singularity problem of the integral equations at characteristic frequencies, the Burton–Miller method is employed in the formulation. The integral equations are then discretized by using the two-nodal constant elements and a collocation procedure. The hyper and weakly singular integrals in each element containing the collocation points are computed analytically and numerically respectively (stark singularity does not appear).

In outdoor acoustic, the ground surface can be seen occasionally as an infinite surface with a given constant impedance. In this case the ground surface can either be discretized by using finite and infinite boundary elements or simulated by using the Green functions for impedance half space. The method to compute such Green functions presented in Ref. 1, is improved and used in the code. A formulation of the infinite boundary element is proposed. The two BEM approaches for the impedance half space problems are tested by means of examples and the agreement is found to be good.
COMPARISON OF TWO AND THREE SPATIAL DIMENSIONAL SOLUTIONS OF THE WAVE EQUATION AT OCEAN-BASIN SCALES IN THE PRESENCE OF INTERNAL WAVES
Authors: SPIESBERGER JOHN L.
Published: June 2008

Numerical solutions are given for a parabolic approximation to the acoustic wave equation at 75 Hz in two and three spatial dimensions to determine if azimuthal coupling of the field significantly affects horizontal coherence. Coupling is a small effect at 4000 km in the presence of internal gravity waves. This implies that accurate solutions are possible using computations from uncoupled vertical slices through the field. The shape of horizontal coherence is inconsistent with shapes given by two theories. Estimates of horizontal coherence at 4000 km and 25, 50, and 75 Hz are 10, 2, and 1 km respectively.
IMPROVING UNIVERSITY PERFORMANCE THROUGH ICT BASED KNOWLEDGE MANAGEMENT SYSTEM
Authors: NUMPRASERTCHAI SOMCHAI , POOVARAWAN YUEN
Published: June 2008

Public universities are widely regarded not only as teaching establishments but also as organizations that create new knowledge and support social communities. Due to great competition at higher education level, a number of universities have implemented strategies and tools that improve the quality of students and research results and provide several community services for building their competitiveness. Knowledge management (KM) is usually recommended as one of the important roles to improve efficiency and effectiveness in university mandates and provide many benefits to a university.

Kasetsart University (KU), one of the Thailand's largest and most progressive public universities, has applied ICT based KM in its strategies in order to overcome resource scarcity and enhance its capabilities. It has developed several KM practices and projects using ICT in several activities which relate to mandates.

The initial findings indicate that (1) an ICT based KM system significantly enhances the university's performance in terms of its quality of students, research results and innovative community services. (2) The specific KM practices and projects support different aspects of university mandates. This ICT based KM system has been implemented and proved to be practical. This system is suitable for the university in terms of its educational mission, research, and community services. This model could be the best practice for further improvement and could be customized to fit other universities in other developing countries.
THE CONSTRUCTION OF INNOVATION NETWORKS AND THE DEVELOPMENT OF TECHNOLOGICAL CAPABILITIES OF INDUSTRIAL CLUSTERS IN CHINA
Authors: WU XIAOBO , GU ZHIGANG , ZHANG WEI
Published: June 2008

Innovation network has been viewed as one of the most important means in improving technological capabilities for decades. Based on literature review, this paper presents a conceptual model on the relationships between the construction of innovation networks and the development of technological capabilities of industrial clusters in China. Applying this model we conduct a case study on reviewing history path of Zhejiang Haining leather industrial cluster. Conclusions can be drawn as follows: firstly, industrial clusters in China take on specific paradigm for technology acquisition by constructing external innovation networks; secondly, assimilation of acquired external technology resources and their translation into technological capabilities of clustered firms need support from internal innovation networks of industrial clusters; thirdly, quasi-external network, as a nexus between external and internal innovation networks of industrial clusters supported by collective learning, helps promote the effective development of technological capabilities of industrial clusters in China.
ON THE R&D PRIORITY SETTING IN TECHNOLOGY FORESIGHT: A DEA AND ANP APPROACH
Authors: LEE HAKYEON , LEE CHANGYONG , SEOL HYEONJU , PARK YONGTAE
Published: June 2008

This paper propose a systematic approach to setting R&D priorities of emerging technologies in the technology foresight context. The proposed approach consists of two stages with two multiple criteria decision making methods. Firstly, socio-economic cost-benefit analysis based on data envelopment analysis with macro-level criteria is conducted to screen initial set of emerging technologies. The second stage deals with the detailed prioritization of the emerging technologies that have been selected at the first stage. Analytic network process is employed here with micro-level criteria. The set of derived R&D priorities of emerging technologies is expected to aid R&D policy-making.
Influence of AMP-activated protein kinase and calcineurin on metabolic networks in skeletal muscle
Authors: Long Yun Chau , Zierath Juleen R.
Published: June 2008

Skeletal muscle fibers differ considerably in their metabolic and physiological properties. Skeletal muscle displays a high degree of metabolic flexibility, which allows the myofibers to adapt to various physiological demands by shifting energy substrate utilization. Transcriptional events play a pivotal role in the metabolic adaptations of skeletal muscle. The expression of genes essential for skeletal muscle glucose and lipid metabolism is tightly coordinated in support of a shift in substrate utilization. AMP-activated protein kinase (AMPK) and calcineurin (a calcium-regulated serine/threonine protein phosphatase) regulate skeletal muscle metabolic gene expression programs in response to changes in the energy status and levels of neuronal input, respectively. AMPK and calcineurin activate transcriptional regulators such as peroxisome proliferator-activated receptor-γ coactivator-1α and myocyte enhancer factor as well as increase skeletal muscle oxidative capacity and mitochondrial gene expression. Activation of either the AMPK or calcineurin pathway can also enhance the glycogen storage capacity and insulin sensitivity in skeletal muscle. Characterization of pathways governing skeletal muscle metabolism offers insight into physiological and pharmacological strategies to prevent or ameliorate peripheral insulin resistance associated with metabolic disorders such as type 2 diabetes.
Comparative hepatic gene expression profiling of rats treated with 1H,1H,2H,2H-heptadecafluorodecan-1-ol or with pentadecafluorooctanoic acid
Authors: Nilsen Anja Julie , Landin Maria A. , Haug Kristin H. , Fonnum Frode , Berger Urs , Osmundsen Harald
Published: June 2008

Pentadecafluorooctanoic acid is an established peroxisome proliferator. Little is known about effects of treatment with 1 H,1 H,2 H,2 H-heptadecafluorodecan-1-ol, which is metabolized to pentadecafluorooctanoic acid. We compared effects of various dosages (3, 10, or 25 mg/kg body wt) of each of these compounds on hepatic gene expression in rats with microarrays. Microarray data were validated by real-time RT-PCR. Expression data were also correlated with hepatic activities of selected enzymes and with hepatic levels of pentadecafluorooctanoic acid and 1 H,1 H,2 H,2 H-heptadecafluorodecan-1-ol. Pentadecafluorooctanoic acid caused the more powerful change in gene expression, in terms of both number of genes affected and extent of change in expression. Across the dosages used pentadecafluorooctanoic acid and 1 H,1 H,2 H,2 H-heptadecafluorodecan-1-ol caused significant ( P ≤ 0.05) changes in expression for 441 and 105 genes, respectively. With 1 H,1 H,2 H,2 H-heptadecafluorodecan-1-ol ∼38% of the 105 genes exhibited decreased expression with a dose of 25 mg/kg body wt, these genes also appearing less responsive to treatment at the lower dosages. Bioinformatic analysis suggested that these genes are associated with regulatory functions. With pentadecafluorooctanoic acid, increasing dosage up to 10 mg/kg body wt brought about progressive increase in expression of affected genes. Pathways analysis suggested similar effects of the two compounds on lipid and amino acid metabolism. Marked differences were also found, particularly with respect to effects on genes related to oxidative phosphorylation, oxidative metabolism, free radical scavenging, xenobiotic metabolism, and complement and coagulation cascades.
MicroRNA and cardiac pathologies
Authors: Latronico Michael V. G. , Catalucci Daniele , Condorelli Gianluigi
Published: June 2008

MicroRNA has been shown to be essential for correct cardiovascular development and physiology in a number of recent reports. Studies have also started to characterize the link between specific microRNAs and aspects of pathogenesis—such as chamber morphogenesis, conduction, and contraction—and between microRNA expression signatures and pathological cardiac phenotypes—such as hypertrophy, ischemic cardiomyopathy, dilated cardiomyopathy, and aortic stenosis. Congenital anomalies of the heart may also be associated with the dysregulation of specific microRNAs. Here we report on the latest findings.
Early Deletion and Late Positive Selection of T‐Cells Expressing a Male‐Specific Receptor in T‐Cell ReceptorTransgenic Mice
Authors: Teh Hung Sia , Kishi Hiroyuki , Scott Bernadette , Borgulya Peter , Von Boehmer Harald , Kisielow Pawel
Published: June 2008

The ontogeny of T cells in T‐cell receptor (TCR) transgenic mice, which express a transgenic
αβ heterodimer, specific for the male (H‐Y) antigen in association with H‐2Db, was determined. The transgenic α chain was expressed on about 10% of the fetal thymocytes on day
14 of gestation. About 50% of day‐15 fetal thymocytes expressed both α and β transchains and virtually all fetal thymocytes expressed the transgenicαβ
heterodimer by day 17. The
early expression of the transgenic TCR on CD4-8- thymocytes prevented the development of γδ cells, and led to accelerated growth of thymocytes and an earlier expression of CD4 and
CD8 molecules. Up to day 17, no significant differences in T‐cell development could be
detected between female and male thymuses. By day 18 of gestation, the male transgenic
thymus contained more CD4-8- thymocytes than the female transgenic thymus. The
preponderance of CD4-8- thymocytes in the male transgenic thymus increased until birth
and was a consequence of the deletion of the CD4+8+ thymocytes and their CD4-8+ precursors. By the time of birth, the male transgenic thymus contained half the number of cells as the female transgenic thymus. The deletion of autospecific precursor cells in the male
transgenic mouse began only at day 18 of gestation, despite the fact that the ligand could
already be detected by day 16.

The preferential accumulation of CD4-8+ T cells, which expressed a high density of the transgenic TCR, occurred only after birth and was .obvious in 6‐week‐old female thymus.
These data support the hypothesis that the positive selection of T cells expressing this transgenic
heterodimer may involve two steps, i.e., the commitment of CD4+8+ thymocytes to the
CD4-8+ lineage following the interaction of the transgenic TCR with restricting major histocompatibility
molecules, followed by a slow conversion of CD4+8+ thymocytes into CD4-8+
T cells.

In normal mice, the precursors of CD+4+8 and single positive thymocytes have the
CD4-8- CD3-J11d+ (or M1/69 +) phenotype. Because of the early expression of the transgenic
αβ heterodimer, this population was not detected in adult transgenic mice. All CD4-8- M1/
69+ cells expressed the transgenic receptor associated with CD3 and could be readily grown
in media containing T‐cell lectins and interleukin 2.
Structure of Germline Immunoglobulin Heavy‐Chain γ1 Transcripts in Interleukin 4 Treated Mouse Spleen Cells
Authors: Xu Minzhen , Stavnezer Janet
Published: June 2008

Antibody class switching is mediated by a DNA recombination event that replaces the Cμ gene with one of the other heavy (H) chain constant region (CH) genes located 3′ to the Cμ gene. The regulation of this process is essential to the immune response because different
CH regions provide different biological functions. Correlative evidence indicates that the
isotype (class) specificity of the switch is determined by the accessibility of specific CH genes
as indicated by hypomethylation and transcriptional activity. For example, RNAs transcribed
from specific unrearranged CH genes are induced prior to switching under conditions that
promote subsequent switching to these same CH genes. The function of transcription of
these germline CH genes is unknown. In this report, we describe the structure of RNA transcribed
from unrearranged γ1 genes in mouse spleen cells treated with LPS plus .a HeLa cell
supernatant containing recombinant interleukin 4. The germline γl RNA is initiated at
multiple start sites 5′ to the tandem repeats of the γ1 switch (Sγ1) region. As is true for
analogous RNAs transcribed from unrearranged γ2b and c genes, the germline γ1 RNA has an exon transcribed from the region 5′ to Sγ1 sequences, which is spliced at a unique site to
the Cr gene. The germline γ1 RNA has an open‐reading frame (ORF) that potentially encodes a small protein 48 amino acid in length.
Are the IL‐2 Receptors Expressed in the Murine Fetal Thymus Functional?
Authors: Zoúñiga-Pflücker Juan Carlos , Smith Kendall A. , Tentori Lucio , Pardoll Drew M. , Longo Dan L. , Kruisbeek Ada M.
Published: June 2008

It is well established that the majority of murine fetal thymocytes (day 15 of gestation)
express receptors for interleukin 2 (IL‐2), but the functional significance of these IL‐2 receptors
(IL‐2Rs) is not clear. In situ hybridization data show a developmentally regulated
expression of IL‐2 and IL‐2R mRNA. IL‐2 binding studies were performed on fetal thymocytes
and the results show the presence of both high (kD ≅ 20 pM) and low (kD ≅ 10 nM)
affinity IL‐2Rs. These IL‐2Rs are indeed functional: intact fetal thymic lobes (but not cell
suspensions) cultured in IL‐2 exhibited an in vitro proliferative response at 20 pM of IL‐2,
corresponding with the presence of a functional high‐affinity IL‐2R on fetal thymocytes. The
IL‐2‐dependent growth was primarily observed in the IL‐2R + thymic subset, which contains
the CD3‐/CD4‐/CD8‐ precursor thymocytes. Furthermore, in vitro blocking of IL‐2 in
intact fetal thymic lobes resulted in a reduction in the cell yield, which predominantly
affected the expansion of the immature CD3‐/CD4‐/CD8‐thymocytes. Our findings
strongly support the concept that the IL‐2/IL‐2R pathway is responsible for the proliferation
of precursor cells within the fetal thymus.
Identification of an IL‐4‐Inducible Gene Expressed in Differentiating Lymphocytes and Male Germ Cells
Authors: Nabavi Nasrin , Grusby Michael J. , Finn Patricia W. , Wolgemuth Debra J. , Glimcher Laurie H.
Published: June 2008

Interleukin 4 (IL‐4) is a cytokine that is involved in the differentiation of B and T lymphocytes.
In this report, we describe the identification of a novel gene, N.52, which was cloned
from the murine pre‐B cell line R8205 grown in the presence of IL‐4 for 48 hr. Although
N.52 expression is detectable at low levels in unstimulated R8205 cells, the level of N.52
dramatically increases after only .4 hr exposure to IL‐4 and remains at a high .level up to
48 hr. Although N.52 expression is low or absent in normal spleen B and T cells, its expression
can be induced by the differentiation signals delivered by LPS in B cells and by Con A
in T‐cell hybrids. While N.52 mRNA is absent in all highly differentiated organs, it is detectable
in stem cell harboring lymphoid tissues such as bone marrow, fetal liver, and thymus.
Furthermore, N.52 mRNA is expressed at strikingly high levels in the testis, specifically in
differentiating male germ cells. It is induced by differentiation signals triggered by the
combination of cyclic AMP and retinoic acid in teratocarcinoma F9 cells. Taken together,
these data suggest that N.52 is a developmentally regulated gene whose expression in cells
of the immune and reproductive systems may be controlled by stimuli that induce differentiation.
Phenotypic Characterization of Chicken Bursal Stromal Elements
Authors: Boyd Richard L. , Wilson Trevor J. , Ward Harry A. , Mitrangas Kathy
Published: June 2008

Many, if not all, of the different phases of intrabursal B‐cell maturation are controlled by the
stromal components. We have used an extensive panel of mAb to provide a detailed
phenotypic profile of these cells. Antigenic specificities were defined for the entire surface
epithelium, interfollicular surface epithelium, follicle‐associated epithelium, basement membrane,
basement membrane‐associated epithelium. Several mAb were specific for the
medulla, including those reactive with the stellate network of epithelial cells, isolated macrophages,
and granular, apparently secreted antigens. One of these, MUI‐92, appears to be
bursa‐specific. Two mAb reacted strongly with stellate cortical macrophages, one of which
weakly stained similar cells in the medulla. MHC‐class II antigens were expressed on endothelium
of the corticomedullary junction, macrophagelike cells in the cortex, and medulla
and B lymphocytes predominantly in the cortex. Collectively, these mAb have demonstrated
the antigenically distinct nature of discrete regions in the bursa, but also the continuity of
the surface epithelium with the corticomedullary junction and medulla. They represent
excellent reagents for defining the stromal cell contribution to B‐cell development.
Successful Xenogeneic Transplantation in Embryos: Induction of Tolerance by Extrathymic Chick TissueGrafted into Quail
Authors: Martin Claude , Ohki-Hamazaki Hiroko , Corbel Catherine , Coltey Monique , Le Douarin Nicole M.
Published: June 2008

In previous experiments, we have demonstrated that limb buds engrafted during
embryonic life at E4, between MHC‐mismatched chick embryos, are not only tolerated
after birth, but induce in the recipient a state of split tolerance toward cells expressing
the donor MHC haplotype: donor′s skin grafts are permanently tolerated while a
proliferative response of host′s T cells is generated in MLR by donor–type blood cells. If
the same experiment is performed, using quail embryo as a donor and chick as a
recipient, acute rejection of the quail limb starts during the first two weeks after birth,
thus suggesting that the peripheral type of tolerance induced in these experiments can
be obtained only in allogeneic but not in xenogeneic combinations.

We report here the unexpected result that when a chick limb bud is grafted into a
quail at E4, it is tolerated and, like allogeneic grafts in chickens, induces adult skin‐graft
tolerance without modifying the MLR response. Similar results were obtained with
grafts from another closely related species of bird, the guinea fowl from the Phasianidae
family. In contrast, xenogeneic combinations involving more distant species (chick and
quail as recipients and duck, an Anatidae, as donor) resulted in strong and early rejection
from both recipients. As a whole, quails exhibit a greater ability than the chick to
become tolerant to antigens presented peripherally from early developmental stages. In
adult quails, however, skin grafts performed in either direction (i.e., quail to chick or the
reverse) are rejected according to a similar temporal pattern. Moreover, lymphocytes of
both species are able to respond equally well to quail or chick IL‐2. Several hypotheses
are envisaged to account for these observations. It seems likely that this type of
tolerance is directly related to antigenic load because the load in chick to quail wing
chimeras is larger than that in quail to chick chimeras. This view is supported by the
protracted delay in graft rejection observed when two quail wing buds instead of one
are grafted into chickens.
Stromal‐Cell and Cytokine‐Dependent Lymphocyte Clones Which Span the Pre‐B‐ to B‐Cell Transition
Authors: Ishihara Katsuhiko , Medina Kay , Hayashi Shin-Ichi , Pietrangeli Carolynn , Namen Anthony E. , Miyake Kensuke , Kincade Paul W.
Published: June 2008

Five stromal‐cell‐dependent lymphocyte clones are described that correspond to late pre‐B
or early B‐cell stages of differentiation.They are useful for determining the molecular
requirements for pre‐B replication, for studying the stromal cells that supply those factors,
and for delineating the final sequence of differentiation events as newly formed lymphocytes
prepare to exit the bone marrow. The efficiency of lymphocyte growth at limiting dilution
varied substantially on different stromal‐cell clones and may reflect functional heterogeneity
of stromal cells. Most lymphocyte clones were similar to uncloned lymphocytes from
Whitlock‐Witte cultures in that they responded only transiently to interleukin‐7 (IL‐7) and
then died, unless maintained on a stromal‐cell clone. One unusual lymphocyte clone (2E8)
was propagated for more than 1 year in IL‐7 alone and was selectively responsive to that
cytokine. Most of the lymphocyte clones were not tumorigenic in immunodeficient mice.
However, one pre‐B clone (1A9)’grew autonomously in culture when held at high density,
responded to conditioned medium from a number of cell lines, and was tumorigenic.
Tumors derived from this clone were infiltrated by stromal cells and lymphocytes taken
from the tumors′ retained characteristics of the original clone. Ly‐6 antigens were inducible
on 2E8 and 1A9 cells, but the lymphocytes were otherwise arrested in differentiation. The
2E8 cells had rearranged and expressed κ light‐chain genes but displayed them on the
surface along with surrogate light chains and μ heavy chains. Thus, expression of authentic
Tight chain need not coincide with termination of surrogate light‐chain utilization in newly
formed B cells. Several glycoproteins have recently been demonstrated to be associated with
surface immunoglobulin (Ig) on mature B‐lineage cells and plasma‐cell tumors. We now
show that one member of this family (approximately 33 kD) was associated with the μ+surrogate light‐chain complex on the 1A9 pre‐B‐cell clone. When compared to mature B
lymphomas, fewer bands coprecipitated with the surface‐labeled Ig isolated from pre‐B‐ and
early B‐cell lines, suggesting that components of the antigen receptor are sequentially
acquired during development. The normal replication and differentiation of pre‐B cells is
probably regulated by complex interactions with multiple cytokines and matrix components
of the marrow microenvironment. Cloned lymphocyte lines that are dependent on stromal
cells should continue to be important tools for molecular definition of those interactions.
CD3- Leukocytes Present in the Human Uterus During Early Placentation: Phenotypic and MorphologicCharacterization of the CD56++ Population
Authors: King Ashley , Balendran Nalini , Wooding P. , Carter N. P. , Loke Y. W.
Published: June 2008

In this study, the CD3‐ LGL/NK cells present in the pregnant human uterus have been
characterized. Phenotypic and morphologic analyses of decidual LGL revealed many similarities
to the minor CD56bright+, CD16- subset in peripheral blood, but there were some
important differences. The relative surface density of CD56+ is greatly increased on decidual
LGL to 22 x that found on the majority of CD56 peripheral blood NK cells. The CD56bright
cells in decidua show LGL morphology, whereas in peripheral blood, they are .mainly
agranular. Proliferation of CD56+ cells occurs predominantly during the nonpregnant secretory
(luteal) phase, indicating these CD56+ uterine LGL do not migrate as terminally differentiated
cells. The appearance of CD56 cells was examined at the ultrastructural level using
immunoelectron microscopy. Cells with phenotypic characteristics of decidual LGL occur in
a higher percentage (1.11%) in the peripheral blood of women of reproductive age than in
men (0.66%). On the basis of these results, it is proposed that the CD56bright+ uterine leukocytes
represent a distinctive, hormonally regulated subset possibly adapted to control human
placentation.
A Novel Adhesion Molecule in the Murine ThymicMicroenvironment: Functional and Biochemical Analysis
Authors: Imami Nesrina , Ladyman Heather M. , Spanopoulou Eugenia , Ritter Mary A.
Published: June 2008

The rat monoclonal antibody (mAb) 4F1, raised against mouse thymic stromal cells,
recognizes cortical epithelium in tissue sections of mouse thymus; however, in flow
cytometry, activated leucocytes (T cells, B cells, and macrophages) and transformed
thymocytes are also positive for the 4F1‐antigen (4F1‐Ag). Western blotting, under both
reducing and nonreducing conditions, demonstrates that the molecule to which 4F1
binds is expressed in four forms, 29, 32, 40, and 43 kD, all of which carry N‐linked
carbohydrate; and that the structure is identical on epithelium and lymphocytes. The
4F1‐Ag on cortical epithelium is partially sensitive to PI‐PLC treatment, whereas on
transformed epithelial and lymphoid cell lines, it was resistant to this enzyme. The
molecule, therefore, may exist in both transmembrane and phosphoinositol‐linked
forms. In functional blocking experiments, mAb 4F1 gave inhibition of both T‐cell
proliferation in MLR and of cytotoxic T‐cell killing of alloantigenic targets; it also
blocked adhesion of transformed thymocytes to thymic epithelial cells in vitro. These
molecular and functional characteristics suggest that the 4F1‐Ag is a novel adhesion
molecule that may be involved both in intrathymic T lymphocyte differentiation and in
peripheral T‐cell function.
Phenotypic Analysis of the Chicken Thymic Microenvironment DuringOntogenic Development
Authors: Wilson Trevor J. , Davidson Natalie J. , Boyd Richard L. , Gershwin M. Eric
Published: June 2008

The development of monoclonal antibodies (mAb) reactive with the thymic
microenvironment has identified distinct subpopulations within the stromal component,
but the function of these subregions in intrathymic T‐cell differentiation remains
essentially an enigma. In this study, we have used such a panel of mAb to examine the
chicken thymus during ontogenic development to gain insight into the contributions of
these thymic regions to the distinct phases of T‐cell development and to further
characterize the development of this organ. Our reagents have demonstrated the
complex differentiation of the primitive endodermal epithelium into more specialized
structures and the development of other thymic stromal components from
mesectodermal cells. We also describe molecules localized to the subcapsular and
perivascular regions, which have an ontogenic expression corresponding to the early
localization and stimulation of thymic precursors and another molecule on the
medullary vasculature expressed corresponding to the exit of mature cells from the
thymus. In addition, two markers of distinct medullary epithelial clusters are initially
expressed corresponding to the appearance of T‐cell receptor‐1 (TcR‐1) and TcR‐2
positive cells in the medulla, respectively. These mAb potentially represent excellent
reagents for further definition of the thymic modulation of T‐cell differentiation.
In Vitro Growth of Thymic Tumor Cell Lines fromXenopus
Authors: Pasquier Louis du , Robert Jacques
Published: June 2008

A spontaneous lymphoid thymus tumor was discovered in a male Xenopus of the MHC
ff genotype. The tumor cell can be transplanted in histocompatible larval ff hosts, but not
in ff adults unless irradiated (3000 rad). The tumor is rejected by allogeneic hosts. The
tumor cells express neither markers of the B‐cell lineage nor MHC encoded molecules;
they express only markers of the T‐cell lineage. Its lymphoid population is clonal as
revealed by the existence of a stable rearrangement pattern of the immunoglobulin
genes. Cell lines growing continuously in vitro have been derived from the tumor.
Interferon Gamma Alters the Phenotype of Rat Thymic Epithelial Cells in Culture and Increases Interleukin‐6Production
Authors: Čolić Miodrag , Pejnović Nada , Kataranovski Milena , Popović Ljiljana , GašIć Sonja , Dujić Aleksandar
Published: June 2008

Rat thymic epithelial cells (TEC) in long‐term culture were characterized by
anticytokeratin monoclonal antibodies (mAbs) and electron microscopy. Phenotypic
analysis performed by a large panel of mAbs showed that the highest percentage of
these cells was of the subcapsular/medullary type.
Recombinant rat interferon (IFN)‐gamma up‐regulated class‐I and class‐II MHC
expression by TEC in culture as confirmed by immunohistochemistry and flow
cytometry, but did not significantly alter other cell markers. TEC supernatants of IFN‐gamma‐
treated cultures showed higher interleukin‐6 (IL‐6) activity, compared to the
control, as determined by proliferation of the IL‐6‐sensitive B9‐cell line. Increased IL‐6
activity was probably not a consequence of increased TEC number in IFN‐gammatreated
cultures because IFN did not significantly stimulate TEC proliferation in vitro. In
contrast, IL‐6 significantly stimulated TEC proliferation, indicating that this cytokine is
not only a regulatory molecule for T‐cell proliferation, but could also be an autocrine
growth factor for thymic epithelium.
Sequences of Cμ and the VH1 Family in LG7, a Clonable Strain of Xenopus, Homozygous for the Immunoglobulin Loci
Authors: Wilson Melanie , Marcuz Anne , Courtet Michéle , Du Pasquier Louis
Published: June 2008

Twenty‐eight heavy‐chain variable (VH1) region genes and the immunoglobulin (IgM)
heavy‐chain constant region of an isogenic Xenopus hybrid, X. laevis/X, gilli, LG7, have
been sequenced. The LG7 clone represents the first Xenopus hybrid that is homozygous
for the IgH locus. The VH1 family was specifically investigated because VH1 genes are
used by the antibodies produced during the Xenopus antidinitrophenol (DNP) response,
These VH1 germ‐line sequences establish a so‐called ”dictionary— that is available for
studying somatic hypermutational mechanisms in immunized frogs.
Induction of Apoptosis in Thymocytes by ProstaglandinE2 In Vivo
Authors: Mastino Antonio , Piacentini Mauro , Grelli Sandro , Favalli Cartesio , Autuori Francesco , Tentori Lucio , Oliverio Serafina , Garach Enrico
Published: June 2008

In vivo administration in mice of a synthetic analog of prostaglandin E2 (PGE2) caused a
selective and dramatic decrease of CD4+CD8+ double‐positive, CD3/T‐cell‐receptor‐αb10
cells in the thymus. This loss was corticosteroid‐independent and not affected by
Cyclosporin A. The disappearance of CD4+CD8+ thymocytes was strictly correlated with
the induction of apoptosis inside the thymus as shown by morphological studies and by
the induction of intracellular transglutaminase expression. Considering that PGE2 has
been found to be produced by different cell populations inside the thymus, these results
indicate that PGE2 may act as endogenous signals for apoptosis during T‐cell
differentiation.
Fusion of a scid Pre‐B Cell with a Wild Type (Myeloma)B Cell Results in Correct Rearrangement of a V(D)JRecombination Substrate
Authors: Zhao Jian , Storb Ursula
Published: June 2008

Mice with the scid mutation have a defect in the V(D)J recombinase. In order to
determine whether the SCID product is normally present in mature B cells that do not
have the recombinase activity, scid pre‐B cells were fused with myeloma cells. It was
found that in the hybrid cells, a rearrangement test gene was correctly joined
immediately after fusion. The same test gene was aberrantly rearranged in the scid pre‐B
cells. Stable hybrids between the scid pre‐B and the myeloma cells had lost the
expression of RAG‐1 and RAG‐2 genes, supporting the previous finding of an inhibitor
of rearrangement in myeloma cells that acts shortly after fusion. Thus, mature B cells
apparently contain the SCID product, the wild type SCID function is not competitively
interfered with by products present in scid pre‐B cells, and the SCID product seems not
to be a target for the recombinase inhibitor.
A Striational Muscle Antigen and Myasthenia Gravis‐AssociatedThymomas Share an Acetylcholine‐Receptor Epitope
Authors: Marx Alexander , Osborn Mary , Tzartos Socrates , Geuder Kerstin I. , Schalke Berthold , Nix Wilfried , Kirchner Thomas , MüLler-Hermelink Hans-Konrad
Published: June 2008

The coincidence of autoantibodies against the acetylcholine receptor (AChR) and muscle
striational antigens (SA) is a characteristic finding in thymoma‐associated myasthenia
gravis (MG), but their origins are still unresolved. Some common muscle antigens that
were shown to be targets of anti‐SA autoantibodies in thymoma‐associated MG have
also been detected in normal or neoplastic thymic epithelial cells, suggesting that the
release of (eventually altered) antigens from the thymic tumors could elicit SA
autoimmunity. In contrast to this model, we report here that titin, which is a recently
reported target of SA autoimmunity, is not expressed in thymomas. In addition, we
show that skeletal muscle type‐II fibers exhibit a striational immunoreactivity with
monoclonal antibody mAb155, which was previously identified to label a very
immunogenic cytoplasmic epitope of the AChR and neoplastic epithelial cells of MGassociated
thymomas. We conclude from these findings that titin autoimmunity in
thymoma‐associated MG is either due to a molecular mimicry mechanism involving
tumor antigens (other than titin) or is a secondary phenomenon following release of titin
from muscle. Based on the common immunoreactivity of the AChR, a striational antigen
and thymoma, we suggest as the pathogenetic mechanism of thymoma‐associated MGa
"circulus vitiosus" in which SA autoimmunity could help maintain the AChR
autoimmunity that is primarily elicited by the thymomas.
The Recognition of Hypothalamo‐NeurohypophysialFunctions by Developing T Cells
Authors: Robert F. R. , Martens H. , Cormann N. , Benhida A. , Schoenen J. , Geenen V.
Published: June 2008

Neuropeptide signals and specific neuropeptide receptors have been described in the
thymus supporting the concept of a close dialogue between the neuroendocrine and the
immune systems at the level of early T‐cell differentiation. In this paper, we review
recent data about neurohypophysial (NHP)‐related peptides detected in the thymus
from different species. We suggest that we are dealing in fact with other member(s) of
the NHP hormone family, which seems to exert its activity locally through a novel
model of cell‐to‐cell signaling, that of cryptocrine communication. This model involves
exchange of signals between thymic epithelial cells and developing thymocytes. The
NHP‐related peptides have been shown to trigger thymocyte proliferation and could
induce immune tolerance of this highly conserved neuroendocrine family.
IgH Diversity In an Individual With Only One Million B Lymphocytes
Authors: Lee Ada , Desravines Soléenne , Hsu Ellen
Published: June 2008

Immunoglobulin sequences from an individual Xenopus laevis froglet were analyzed for
combinatorial and junctional diversity. In an animal with about 106 B lymphocytes, at
least 26 out of the 56 VH1 genes available in a diploid genome were expressed, as were
all JH segments. Junctional diversity was similar to that observed in Xenopus tadpole
sequences, that is, little or no N diversification was found and the recombination site
sometimes occurred in a region of V/D or D/J homology. The froglet IgH diversity is
further restricted by the elimination of D‐gene participation through direct V to J
joining. Of the six complementary‐determining regions (CDR) contributing to the
structure of the antigen‐combining site, CDR3 is the most variable in sequence and
structure. Froglet IgH CDR3 are restricted to both aspects. Compared to IgH sequences
isolated from a 5‐month‐old adult, froglet CDR3 were, on the average, two codons
shorter; overall, 58% of the froglet Ig sequences isolated carried CDR3 of ≤ 7 codons,
compared to 30% of the adult sequences. In addition to being shorter, the
tadpole/froglet CDR3 are less variable in sequence, as the absence of N regions also
results in the V/D and D/J junctions being derived from germline elements. We
therefore suggest that latent anti‐adult specificities are not eliminated in situ, in the
tadpole, but rather that such germline gene segments, singly or in their combinations
thereof, that can potentially react to adult self‐epitopes after metamorphosis have been
counterselected during the course of evolution.
Characterization of Thymic Nurse‐Cell Lymphocytes, Using an Improved Procedure for Nurse‐Cell Isolation
Authors: Lahoud Mireille , Vremec David , Boyd Richard L. , Shortman Ken
Published: June 2008

Thymic nurse cells (TNC), multicellular complexes consisting of lymphoid cells
enclosed within cortical epithelial cells, were isolated from mouse thymus by a modified
procedure allowing immunofluorescent labeling and flow cytometric analysis of their
lymphoid contents (TNC‐L). Collagenase was the only protease used for tissue
digestion, to ensure that surface antigen markers remained intact. Zonal unit‐gravity
elutriation was used to enrich the TNC on the basis of their high sedimentation rate,
followed by immunomagnetic bead depletion to remove residual mononuclear cell
contaminants and a density separation to remove debris. The TNC‐L were then released
from inside TNC by a short period of culture. The measured contamination of TNC‐L
with exogenous thymocytes was around 0.5%. Three‐color immunofluorescent labeling
revealed that TNC‐L included, as well as a maiority of immature CD4+8+3low thymocytes,
about 12% of apparently mature CD4+8-3high and CD4-8+3high thymocytes. TNC are
located in the cortex, where mature cells are rare; the occurrence of mature phenotype
cells within these structures suggests that they represent a microenvironment for the
selection and generation of mature T cells.
Is There an Interspecific Diversity of the Thymic Microenvironment?
Authors: de Souza Lucia Renata Meireles , Trajano Valeria , Savino Wilson
Published: June 2008

Thymic epithelial cells (TEC) heterogeneity suggests the existence of functional subsets.
Anti‐cytokeratin (Anti‐CK) monoclonal antibodies (MAb), markers of epithelial
differentiation, have been used to detect TEC subsets in rodents and humans. These
MAb revealed a different topography of CK‐defined TEC subsets in mice and humans,
leading us to carry out a comparative study of mammalian thymuses. Our study
showed that the distribution pattern of cytokeratins in the thymic epithelium is complex
and unique, with coexpression of CK typical of simple and stratified epithelia.
Moreover, we demonstrated an interspecific diversity of CK expression within the
thymic lobules. Interestingly, such diversity was not a general phenomenon for the
expression of any thymic microenvironmental proteins, because the location of
extracellular matrix components was essentially similar in the mammalian species
studied.